Researcher Database

Jian Ping Gong
Faculty of Advanced Life Science Advanced Transdisciplinary Science Soft & Wet Matter Science
Professor

Researcher Profile and Settings

Affiliation

  • Faculty of Advanced Life Science Advanced Transdisciplinary Science Soft & Wet Matter Science

Job Title

  • Professor

Degree

  • Doctor of Science(Hokkaido University)
  • Doctor of Engineering(Tokyo Institute of Technology)

URL

J-Global ID

Profile

  • Jian Ping Gong obtained her bachelor's degree in electronic physics from Zhejiang University, China, and received her Master's degree in polymer science from Ibaraki University, Japan. She studied high Tc superconductors at the Tokyo Institute of Technology for two years where she earned her Doctor of Engineering. She has been working on polymer science since 1993 at Hokkaido University, and received her Doctorate of Science in polymer sciences. She also serves on the editorial and advisory boards of the Biointerphases, Asia Materials, Soft Matter, and Macromolecules. She focuses on the study of physical and biological properties of soft and wet matters.

Research Interests

  • Sacrificial bond   Regenerative medicine   Biomaterials   Cell Scaffold   Artificial cartilage   Lubrication   Friction   Toughness   Mechanical strength   Soft and wet   Polymer gel   

Research Areas

  • Nanotechnology/Materials / Basic physical chemistry
  • Life sciences / Biomaterials
  • Life sciences / Biomedical engineering
  • Natural sciences / Bio-, chemical, and soft-matter physics
  • Nanotechnology/Materials / Polymer materials
  • Nanotechnology/Materials / Thin-film surfaces and interfaces
  • Life sciences / Biophysics

Academic & Professional Experience

  • 2010/04 - Today Faculty of Advanced Life Science, Hokkaido University Professor
  • 2005/10 - Today Zhejiang University, China Guest Professor
  • 2016/04 - 2019/03 Hokkaido University GI-CoRE Director, Global Station for Soft Matter
  • 2006/04 - 2010/03 Faculty of Science, Hokkaido University Professor
  • 2004/12 - 2007/03 Japan Science and Technology Agency SORST Researcher (concurrent)
  • 2003/09 - 2006/03 Graduate School of Science, Hokkaido University Professor
  • 2001/10 - 2004/11 Japan Science and Technology Agency PRESTO Researcher (concurrent)
  • 1995/04 - 2003/09 Graduate School of Science, Hokkaido University Associate Professor
  • 1997/11 - 1998/01 University of California, San Francisco, USA Visiting Associate Professor
  • 1994/10 - 1995/03 School of Science, Hokkaido University Associate Professor
  • 1993/04 - 1994/09 School of Science, Hokkaido University Research Associate
  • 1983/09 - 1986/09 Nanjing Electronic Devices Institute, China Researcher

Education

  • 1991/04 - 1993/03  Tokyo Institute of Technology  Division of Integrated Science and Engineering
  • 1989/04 - 1991/03  Ibaraki University, Japan
  • 1979/09 - 1983/08  Zhejiang University, China

Association Memberships

  • Royal Society of Chemistry   RESEARCH GROUP ON POLYMER GELS   JAPANESE SOCIETY OF BIOTRIBOLOGY   THE CHEMICAL SOCIETY OF JAPAN   THE SOCIETY OF RHEOLOGY, JAPAN   THE SOCIETY OF POLYMER SCIENCE, JAPAN   JAPANESE SOCIETY OF BIORHEOLOGY   The Society of Rubber Science and Technology, Japan   

Research Activities

Published Papers

  • Ya Nan Ye, Kunpeng Cui, Wei Hong, Xueyu Li, Chengtao Yu, Dominique Hourdet, Tasuku Nakajima, Takayuki Kurokawa, Jian Ping Gong
    Proceedings of the National Academy of Sciences 118 (14) e2014694118 - e2014694118 0027-8424 2021/04/06 [Refereed][Not invited]
     
    Tough soft materials usually show strain softening and inelastic deformation. Here, we study the molecular mechanism of abnormally large nonsoftening, quasi-linear but inelastic deformation in tough hydrogels made of hyperconnective physical network and linear polymers as molecular glues to the network. The interplay of hyperconnectivity of network and effective load transfer by molecular glues prevents stress concentration, which is revealed by an affine deformation of the network to the bulk deformation up to sample failure. The suppression of local stress concentration and strain amplification plays a key role in avoiding necking or strain softening and endows the gels with a unique large nonsoftening, quasi-linear but inelastic deformation.
  • Jun Suzuka, Masumi Tsuda, Lei Wang, Shinji Kohsaka, Karin Kishida, Shingo Semba, Hirokazu Sugino, Sachiyo Aburatani, Martin Frauenlob, Takayuki Kurokawa, Shinya Kojima, Toshihide Ueno, Yoshihiro Ohmiya, Hiroyuki Mano, Kazunori Yasuda, Jian Ping Gong, Shinya Tanaka
    Nature Biomedical Engineering 2021/03/29 [Refereed][Not invited]
  • Rong Long, Chung-Yuen Hui, Jian Ping Gong, Eran Bouchbinder
    Annual Review of Condensed Matter Physics 12 (1) 71 - 94 1947-5454 2021/03/10 [Refereed][Invited]
     
    The fracture of highly deformable soft materials is of great practical importance in a wide range of technological applications, emerging in fields such as soft robotics, stretchable electronics, and tissue engineering. From a basic physics perspective, the failure of these materials poses fundamental challenges due to the strongly nonlinear and dissipative deformation involved. In this review, we discuss the physics of cracks in soft materials and highlight two length scales that characterize the strongly nonlinear elastic and dissipation zones near crack tips in such materials. We discuss physical processes, theoretical concepts, and mathematical results that elucidate the nature of the two length scales and show that the two length scales can classify a wide range of materials. The emerging multiscale physical picture outlines the theoretical ingredients required for the development of predictive theories of the fracture soft materials. We conclude by listing open challenges and future investigation directions. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 12 is March 10, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
  • Sairam Pamulaparthi Venkata, Kunpeng Cui, Jingyi Guo, Alan Zhender, Jian Ping Gong, Chung-Yuen Hui
    Soft Matter 1744-683X 2021/03 [Refereed][Not invited]
     

    A finite strain nonlinear viscoelastic constitutive model is used to study the uniaxial tension behaviour of a chemical Polyampholyte (PA) gel. This PA gel is cross-linked by chemical and physical...

  • Youfeng Yue, Yasuo Norikane, Jian Ping Gong
    Advanced Optical Materials 2002198 - 2002198 2195-1071 2021/02/16 [Refereed][Not invited]
  • Kunpeng Cui, Jian Ping Gong
    Aggregate 2692-4560 2021/02/13 [Refereed][Invited]
  • Sairam Pamulaparthi Venkata, Kunpeng Cui, Jingyi Guo, Alan T. Zehnder, Jian Ping Gong, Chung-Yuen Hui
    Extreme Mechanics Letters 43 101184 - 101184 2352-4316 2021/02 [Refereed][Not invited]
  • Hailong Fan, Jiahui Wang, Jian Ping Gong
    Advanced Functional Materials 2009334 - 2009334 1616-301X 2020/12/28 [Refereed][Not invited]
  • 骨リモデリングプロセスを利用したハイドロゲルの骨への高強度接着―人工軟骨への応用に向けて
    樫村尚宏, 野々山貴行, 龔剣萍
    医学のあゆみ 275 (11) 1203 - 1209 2020/12/12 [Not refereed][Invited]
  • Takayuki Nonoyama, Lei Wang, Masumi Tsuda, Yuki Suzuki, Ryuji Kiyama, Kazunori Yasuda, Shinya Tanaka, Kousuke Nagata, Ryosuke Fujita, Naoya Sakamoto, Noriyuki Kawasaki, Hisayoshi Yurimoto, Jian Ping Gong
    Advanced healthcare materials 10 (3) 2001731  2020/11/16 [Refereed][Not invited]
     
    Tough double network (DN) hydrogels are promising substitutes of soft supporting tissues such as cartilage and ligaments. For such applications, it is indispensable to robustly fix the hydrogels to bones with medically feasible methods. Recently, robustly bonding the DN hydrogels to defected bones of rabbits in vivo has been proved successful. The low crystalline hydroxyapatite (HAp) of calcium-phosphate-hydroxide salt coated on the surface layer of the DN hydrogels induced spontaneous osteogenesis penetrating into the semi-permeable hydrogels to form a gel/bone composite layer. In this work, the 44 Ca isotope-doped HAp/DN hydrogel is implanted in a defect of rabbit femoral bone and the dynamic osteogenesis process at the gel/bone interface is analyzed by tracing the calcium isotope ratio using isotope microscopy. The synthetic HAp hybridized on the surface layer of DN gel dissolves rapidly in the first two weeks by inflammation, and then the immature bone with a gradient structure starts to form in the gel region, reutilizing the dissolved Ca ions. These results reveal, for the first time, that synthetic HAp is reutilized for osteogenesis. These facts help to understand the lifetime of bone absorbable materials and to elucidate the mechanism of spontaneous, non-toxic, but strong fixation of hydrogels to bones.
  • Rui Xiao, Thanh-Tam Mai, Kenji Urayama, Jian Ping Gong, Shaoxing Qu
    International Journal of Plasticity 102901 - 102901 0749-6419 2020/11 [Refereed][Not invited]
  • Chung-Yuen Hui, Zezhou Liu, Nicolas Bain, Anand Jagota, Eric R. Dufresne, Robert W. Style, Ryuji Kiyama, Jian Ping Gong
    Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476 (2243) 20200477 - 20200477 1364-5021 2020/11 [Refereed][Not invited]
     
    The surface of soft solids carries a surface stress that tends to flatten surface profiles. For example, surface features on a soft solid, fabricated by moulding against a stiff-patterned substrate, tend to flatten upon removal from the mould. In this work, we derive a transfer function in an explicit form that, given any initial surface profile, shows how to compute the shape of the corresponding flattened profile. We provide analytical results for several applications including flattening of one-dimensional and two-dimensional periodic structures, qualitative changes to the surface roughness spectrum, and how that strongly influences adhesion.
  • Kunpeng Cui, Ya Nan Ye, Chengtao Yu, Xueyu Li, Takayuki Kurokawa, Jian Ping Gong
    ACS Macro Letters 9 (11) 1582 - 1589 2161-1653 2020/10/22 [Refereed][Not invited]
  • Haiyan Yin, Daniel R. King, Tao Lin Sun, Yoshiyuki Saruwatari, Tasuku Nakajima, Takayuki Kurokawa, Jian Ping Gong
    ACS Applied Materials & Interfaces 12 (44) 50068 - 50076 1944-8244 2020/10/21 [Refereed][Not invited]
  • Junchao Huang, Martin Frauenlob, Yuki Shibata, Lei Wang, Tasuku Nakajima, Takayuki Nonoyama, Masumi Tsuda, Shinya Tanaka, Takayuki Kurokawa, Jian Ping Gong
    Biomacromolecules 21 (10) 4220 - 4230 1525-7797 2020/09/27 [Refereed][Not invited]
  • Takahiro Matsuda, Runa Kawakami, Tasuku Nakajima, Jian Ping Gong
    Macromolecules 53 (20) 8787 - 8795 0024-9297 2020/09/25 [Refereed][Not invited]
  • Tomáš Sedlačík, Takayuki Nonoyama, Honglei Guo, Ryuji Kiyama, Tasuku Nakajima, Yoshihiro Takeda, Takayuki Kurokawa, Jian Ping Gong
    Chemistry of Materials 32 (19) 8576 - 8586 0897-4756 2020/09/04 [Refereed][Not invited]
  • David Delgado, Daniel Rudolf King, KUNPENG CUI, Jian Ping Gong, Kenneth R Shull
    ACS Applied Materials & Interfaces 12 (38) 43191 - 43200 1944-8244 2020/08/21 [Refereed][Not invited]
  • Chengtao Yu, Honglei Guo, Kunpeng Cui, Xueyu Li, Ya Nan Ye, Takayuki Kurokawa, Jian Ping Gong
    Proceedings of the National Academy of Sciences 117 (32) 202006842 - 202006842 0027-8424 2020/07/27 [Refereed][Not invited]
     
    The memory of our brain, stored in soft matter, is dynamic, and it forgets spontaneously to filter unimportant information. By contrast, the existing manmade memory, made from hard materials, is static, and it does not forget without external stimuli. Here we propose a principle for developing dynamic memory from soft hydrogels with temperature-sensitive dynamic bonds. The memorizing–forgetting behavior is achieved based on fast water uptake and slow water release upon thermal stimulus, as well as thermal-history-dependent transparency change of these gels. The forgetting time is proportional to the thermal learning time, in analogy to the behavior of brain. The memory is stable against temperature fluctuation and large stretching; moreover, the forgetting process is programmable. This principle may inspire future research on dynamic memory based on the nonequilibrium process of soft matter.
  • Yuki Shibata, Takayuki Kurokawa, Tomoyasu Aizawa, Jian Ping Gong
    Journal of Applied Polymer Science 137 (48) 49583 - 49583 0021-8995 2020/07/24 [Refereed][Not invited]
  • Kunpeng Cui, Ya Nan Ye, Tao Lin Sun, Chengtao Yu, Xueyu Li, Takayuki Kurokawa, Jian Ping Gong
    Macromolecules 53 (13) 5116 - 5126 0024-9297 2020/06/26 [Refereed][Not invited]
  • Wei Cui, Daniel R. King, Yiwan Huang, Liang Chen, Tao Lin Sun, Yunzhou Guo, Yoshiyuki Saruwatari, Chung‐Yuen Hui, Takayuki Kurokawa, Jian Ping Gong
    Advanced Materials 32 (31) 1907180 - 1907180 0935-9648 2020/06/25 [Refereed][Not invited]
  • M. Anamul Haque, Kunpeng Cui, Muhammad Ilyas, Takayuki Kurokawa, Alba Marcellan, Annie Brulet, Riku Takahashi, Tasuku Nakajima, J. Ping Gong
    Macromolecules 53 (12) 4711 - 4721 0024-9297 2020/06/12 [Refereed][Not invited]
  • Shingo Semba, Nobuto Kitamura, Masumi Tsuda, Keiko Goto, Sadamu Kurono, Yoshihiro Ohmiya, Takayuki Kurokawa, Jian Ping Gong, Kazunori Yasuda, Shinya Tanaka
    Journal of Biomedical Materials Research Part A 109 (3) 354 - 364 2020/06/04 [Refereed][Not invited]
  • Daiki Hashimoto, Shingo Semba, Masumi Tsuda, Takayuki Kurokawa, Nobuto Kitamura, Kazunori Yasuda, Jian Ping Gong, Shinya Tanaka
    Biochemical and Biophysical Research Communications 528 (1) 120 - 126 2020/05/23 [Refereed][Not invited]
  • Daniel R. King, Riku Takahashi, Takuma Ikai, Kazuki Fukao, Takayuki Kurokawa, Jian Ping Gong
    ACS Applied Polymer Materials 2 (6) 2350 - 2358 2020/05/15 [Refereed][Not invited]
  • Tasuku Nakajima, Takaharu Chida, Kei Mito, Taayuki Kurokawa, Jian Ping Gong
    Soft Matter 16 (23) 5487 - 5496 2020/05/15 [Refereed][Not invited]
  • Kazuki Fukao, Kazuki Tanaka, Ryuji Kiyama, Takayuki Nonoyama, Jian Ping Gong
    Journal of Materials Chemistry B 8 (24) 5184 - 5188 2020/05/06 [Refereed][Not invited]
     
    Inspired by bone tissues, we mineralized low crystalline hydroxyapatite (HAp) particles in double network (DN) hydrogels, and we observed that the HAp minerals toughen the gels. The contribution of dissipated energy from HAp minerals was over 500% higher than that from the polymer during tensile deformation. We elucidated that the amorphous parts in the HAp minerals break at deformation, acting as energy-dissipative sacrificial bonds. This result implies that not only brittle polymer networks but also minerals can provide sacrificial bonds to toughen soft materials.
  • Hailong Fan, Honglei Guo, Jiahui Wang, Jian Ping Gong
    Giant 1 100005  2020/04 [Refereed][Not invited]
  • Hailong Fan, Jian Ping Gong
    Macromolecules 53 (8) 2769 - 2782 2020/04 [Refereed][Invited]
  • 人工軟骨を目指した高強度ハイドロゲル-リン酸カルシウムの複合化および骨との接着
    Takayuki Nonoyama, Ryuji Kiyama, Kazuki Fukao, Kazunori Yasuda, Takayuki Kurokawa, Jian Ping Gong
    Ceramics Japan 55 (3) 166 - 170 2020/03 [Not refereed][Invited]
  • Meet the phase-separation polymeric gel
    Takayuki Nonoyama, Jian Ping Gong
    The Innovation Platform 1 73 - 74 2020/03 [Not refereed][Invited]
  • Xueyu Li, Kunpeng Cui, Tao Lin Sun, Lingpu Meng, Chengtao Yu, Liangbin Li, Costantino Creton, Takayuki Kurokawa, Jian Ping Gong
    Proceedings of the National Academy of Sciences 117 (14) 7606 - 7612 2020/03 [Refereed][Not invited]
  • Satoshi Hirayama, Takayuki Kurokawa, Jian Ping Gong
    Tribology International 147 106270  2020/02 [Refereed][Not invited]
  • Chung-Yuen Hui, Zezhou Liu, Stuart Leigh Phoenix, Daniel R. King, Wei Cui, Yiwan Huang, Jian Ping Gong
    Extreme Mechanics Letters 35 100642  2020/02 [Refereed][Not invited]
  • Kazuki Fukao, Tasuku Nakajima, Takayuki Nonoyama, Takayuki Kurokawa, Takahiko Kawai, Jian Ping Gong
    Macromolecules 53 (4) 1154 - 1163 2020/01/31 [Refereed][Not invited]
  • Tasuku Nakajima, Takayuki Kurokawa, Hidemitsu Furukawa, Jian Ping Gong
    Soft Matter 1744-683X 2020 [Refereed][Not invited]
     

    The relationship between composition and mechanical properties of tough double-network hydrogels was clarified by systematic experiments and theoretical investigations.

  • Ya Nan Ye, Kunpeng Cui, Tsutomu Indei, Tasuku Nakajima, Dominique Hourdet, Takayuki Kurokawa, Jian Ping Gong
    Macromolecules 52 (22) 8651 - 8661 2019/11/26 [Refereed][Not invited]
  • Tasuku Nakajima, Yuhei Ozaki, Ryo Namba, Kumi Ota, Yuki Maida, Takahiro Matsuda, Takayuki Kurokawa, Jian Ping Gong
    ACS Macro Letters 8 (11) 1407 - 1412 2019/11/19 [Refereed][Not invited]
  • Takayuki Nonoyama, Yong Woo Lee, Kumi Ota, Keigo Fujioka, Wei Hong, Jian Ping Gong
    Advanced Materials 32 (4) 1905878  2019/11 [Refereed][Not invited]
  • Hailong Fan, Jiahui Wang, Zhen Tao, Junchao Huang, Ping Rao, Takayuki Kurokawa, Jian Ping Gong
    NATURE COMMUNICATIONS 10 5127  2041-1723 2019/11 [Refereed][Not invited]
     
    Electrostatic interaction is strong but usually diminishes in high ionic-strength environments. Biosystems can use this interaction through adjacent cationic-aromatic amino acids sequence of proteins even in a saline medium. Application of such specific sequence to the development of cationic polymer materials adhesive to negatively charged surfaces in saline environments is challenging due to the difficulty in controlling the copolymer sequences. Here, we discover that copolymers with adjacent cation-aromatic sequences can be synthesized through cation-ic complex-aided free-radical polymerization. Sequence controlled hydrogels from diverse cation/aromatic monomers exhibit fast, strong but reversible adhesion to negatively charged surfaces in seawater. Aromatics on copolymers are found to enhance the electrostatic interactions of their adjacent cationic residues to the counter surfaces, even in a high ionic-strength medium that screens the electrostatic interaction for common polyelectrolytes. This work opens a pathway to develop adhesives using saline water.
  • Zhen Tao, Hailong Fan, Junchao Huang, Taolin Sun, Takayuki Kurokawa, Jian Ping Gong
    ACS APPLIED MATERIALS & INTERFACES 11 (40) 37139 - 37146 1944-8244 2019/10 [Refereed][Not invited]
     
    Inspired by the toughening mechanism of double-network (DN) gels, tough hydrogel composites with a sandwich structure were fabricated from photoresponsive polymers. By copolymerization of hydrophilic monomers, 2-ureidoethyl methacrylate (UM), and photoresponsive hydrophobic monomers, (2-nitrobenzyloxycarbonylaminoethyl methacrylate (NBOC)) at high concentrations, physical hydrogels that are soft and highly stretchable are formed due to the hydrophobic associations of NBOC, serving as dynamic crosslinkers. By UV irradiation, the physical crosslinking switches into chemical crosslinking, and the soft physical hydrogels transform into rigid and less stretchable chemical hydrogels. By UV curing the surface layers of the physical hydrogels, we prepared hydrogel composites having a sandwiched structure with two rigid outer layers and a soft inner layer. The molecular-level continuous interfaces and matched swelling ratios between the layers ensure the macroscale hydrogel composites' high strength and toughness with a DN gel effect. The outer layers fracture preferentially at deformation, playing a role like the first network of a DN gel, while the inner layer maintains the integrity, playing a role resembling the second network. The evolution of the fracture morphology of the rigid layers gives useful insight into the internal fracture process of DN gels.
  • Toughening Mechanism of Double Network Gels and New Research Trends
    Ryuji Kiyama, Jian Ping Gong
    Journal of Society of Rubber Science and Technology, Japan 92 (9) 352 - 356 2019/09 [Not refereed][Invited]
  • Kunpeng Cui, Ya Nan Ye, Tao Lin Sun, Liang Chen, Xueyu Li, Takayuki Kurokawa, Tasuku Nakajima, Takayuki Nonoyama, Jian Ping Gong
    Macromolecules 52 (19) 7369 - 7378 2019/09 [Refereed][Not invited]
  • Laicong Qiao, Cong Du, Jian Ping Gong, Zi Liang Wu, Qiang Zhen
    Advanced Materials Technologies 4 (11) 1900665  2019/09 [Refereed][Not invited]
  • Honglei Guo, Wei Hong, Takayuki Kurokawa, Takahiro Matsuda, Zi Liang Wu, Tasuku Nakajima, Masakazu Takahata, Taolin Sun, Ping Rao, Jian Ping Gong
    Macromoledules 52 (18) 7114 - 7122 2019/09 [Refereed][Not invited]
  • Daniel R. King, Tsuyoshi Okumura, Riku Takahashi, Takayuki Kurokawa, Jian Ping Gong
    ACS Applied Materials & Interfaces 11 (38) 35343 - 35353 2019/09 [Refereed][Not invited]
  • 鍛えて成長するゲル―破壊による創造の材料科学―
    Takahiro Matsuda, Tasuku Nakajima, Jian Ping Gong
    現代化学 (581) 53 - 57 2019/08 [Not refereed][Invited]
  • Martin Frauenlob, Daniel R. King, Honglei Guo, Seiichiro Ishihara, Masumi Tsuda, Takayuki Kurokawa, Hisashi Haga, Shinya Tanaka, Jian Ping Gong
    Macromolecules 52 (17) 6704 - 6713 2019/08 [Refereed][Not invited]
  • Amber M. Hubbard, Wei Cui, Yiwan Huang, Riku Takahashi, Michael D. Dickey, Jan Genzer, Daniel R. King, Jian Ping Gong
    Matter 1 (3) 674 - 689 2019/08 [Refereed][Not invited]
  • Kohei Murakawa, Daniel R. King, Tao Lin Sun, Honglei Guo, Takayuki Kurokawa, Jian Ping Gong
    Journal of Materials Chemistry B 7 (35) 5296 - 5305 2019/08 [Refereed][Not invited]
  • Vu Ngoc Khiêm, Thanh-Tam Mai, Kenji Urayama, Jian Ping Gong, Mikhail Itskov
    Macromolecules 52 (15) 5937 - 5947 2019/07 [Refereed][Not invited]
  • Joji Murai, Tasuku Nakajima, Takahiro Matsuda, Katsuhiko Tsunoda, Takayuki Nonoyama, Takayuki Kurokawa, Jian Ping Gong
    Polymer 178 121686  2019/07 [Refereed][Not invited]
  • Riku Takahashi, Takuma Ikai, Takayuki Kurokawa, Daniel R. King, Jian Ping Gong
    Journal of Materials Chemistry B 7 (41) 6347 - 6354 2019/07 [Refereed][Invited]
  • Liang Chen, Tao Lin Sun, Kunpeng Cui, Daniel R. King, Takayuki Kurokawa, Yoshiyuki Saruwatari, Jian Ping Gong
    Journal of Materials Chemistry A 7 (29) 17334 - 17344 2019/06 [Refereed][Not invited]
  • Hui Guo, Tasuku Nakajima, Dominique Hourdet, Alba Marcellan, Costantino Creton, Wei Hong, Takayuki Kurokawa, Jian Ping Gong
    Advanced Materials 31 (25) 1900702  2019/05 [Refereed][Not invited]
  • Takahiro Matsuda, Tasuku Nakajima, Jian Ping Gong
    Chemistry of Materials 31 (10) 3766 - 3776 2019/04 [Refereed][Not invited]
  • Yiwan Huang, Daniel R. King, Wei Cui, Tao Lin Sun, Honglei Guo, Takayuki Kurokawa, Hugh R. Brown, Chung-Yuen Hui, Jian Ping Gong
    Journal of Materials Chemistry A 7 (22) 13431 - 13440 2019/04 [Refereed][Not invited]
  • Thanh-Tam Mai, Takahiro Matsuda, Tasuku Nakajima, Jian Ping Gong, Kenji Urayama
    Soft Matter 15 (18) 3719 - 3732 2019/04 [Refereed][Not invited]
  • Kunpeng Cui, Tao Lin Sun, Jian Ping Gong
    Polymer Bulletin 3 1 - 6 2019/03 [Not refereed][Invited]
  • Takahiro Matsuda, Runa Kawakami, Ryo Namba, Tasuku Nakajima, Jian Ping Gong
    Science 363 (6426) 504 - 508 2019/02 [Refereed][Not invited]
  • Ryosuke Hishimura, Tomohiro Onodera, Kazutoshi Hontani, Rikiya Baba, Kentaro Homan, Shinji Matsubara, Zenta Joutoku, WooYoung Kim, Takayuki Nonoyama, Takayuki Kurokawa, Jian Ping Gong, Norimasa Iwasaki
    The American journal of sports medicine 47 (2) 468 - 478 2019/02 [Refereed][Not invited]
     
    BACKGROUND: One of the most important limitations of osteochondral autograft transplantation (OAT) is the adverse effect on donor sites in the knee. To decrease the number and/or size of osteochondral defects, we devised a method with biomaterial implantation after OAT. HYPOTHESIS: OAT augmented by ultrapurified alginate (UPAL) gel enhances cartilage repair capacity. STUDY DESIGN: Controlled laboratory study. METHODS: Seventy-five osteochondral defects in rabbits were divided into 3 groups: osteochondral defects with OAT alone, defects with OAT augmented by UPAL gel (combined group), and defects without intervention as controls. Macroscopic and histological evaluations of the reparative tissues were performed at 4 and 12 weeks postoperatively. Histological evaluation of graft cartilage degradation was also performed. To evaluate the effects of UPAL gel on graft healing, repaired bone volumes and osseointegration of the graft were evaluated. Collagen orientation and the mechanical properties of the reparative tissue and graft cartilage were also evaluated qualitatively. RESULTS: The macroscopic and histological evaluations of the combined group were significantly superior to the other groups at 12 weeks postoperatively. Regarding degenerative change of the graft, the histological scores of the combined group were significantly higher than those of the OAT-alone group. The values of repaired subchondral bone volumes and osseointegration of the graft were almost identical in both groups. Collagen orientation and the mechanical properties of the reparative tissue and graft cartilage were significantly better in the combined group than in the other groups. CONCLUSION: Administration of UPAL gel in OAT enhanced cartilage repair and protected graft cartilage without inhibiting subchondral bone repair and graft survival. CLINICAL RELEVANCE: OAT augmented by UPAL gel decreases the number and/or size of osteochondral grafts, minimizing the risk of donor site morbidity. This combination technique has the potential to improve clinical outcomes and expand the surgical indications for OAT.
  • Shintaro Yashima, Satoshi Hirayama, Takayuki Kurokawa, Thomas Salez, Haruna Takefuji, Wei Hong, Jian Ping Gong
    Soft Matter 15 (9) 1953 - 1959 2019/01 [Refereed][Not invited]
  • Ken-ichi Hoshino, Tasuku Nakajima, Takahiro Matsuda, Takamasa Sakai, Jian Ping Gong
    SOFT MATTER 14 (47) 9693 - 9701 1744-683X 2018/12 [Refereed][Not invited]
     
    In this work, we intended to investigate the relationship between the swelling ratio Q and Young's modulus E of hydrogels from their contracted state to extreme swelling state and elucidate the underlining molecular mechanism. For this purpose, we used tetra-poly(ethylene glycol) (tetra-PEG) gel, whose network parameters are well known, as the polymer backbone, and we succeeded in tuning the swelling of the gel by a factor of 1500 times while maintaining the topological structure of the network unchanged, using an approach combining a molecular stent method and a PEG dehydration method. A master curve of Q-E, independent of the method of obtaining Q, was obtained. Using the worm-like chain model, the experimentally determined master curve can be well reproduced. We also observed that the uniaxial stress-strain curve of the hydrogel can be well predicted by the worm-like chain model using the structure parameters determined from the fitting of the Q-E experimental curve.
  • 刺激応答性発色ゲル
    堀端修人, 中島 祐, 龔 剣萍
    応用物理学会・有機分子・バイオエレクトロニクス分科会 会誌 29 (4) 232 - 235 2018/11 [Not refereed][Invited]
  • Kunpeng Cui, Tao Lin Sun, Xiaobin Liang, Ken Nakajima, Ya Nan Ye, Liang Chen, Takayuki Kurokawa, Jian Ping Gong
    Physical Review Letters 121 (18) 185501  2018/10 [Refereed][Not invited]
  • Ryuji Kiyama, Takayuki Nonoyama, Susumu Wada, Shingo Semba, Nobuto Kitamura, Tasuku Nakajima, Takayuki Kurokawa, Kazunori Yasuda, Shinya Tanaka, Jian Ping Gong
    Acta Biomaterialia 81 60 - 69 2018/10 [Refereed][Not invited]
  • Riku Takahashi, Kouichi Shimano, Haruka Okazaki, Takayuki Kurokawa, Tasuku Nakajima, Takayuki Nonoyama, Daniel R. King, Jian Ping Gong
    Advanced Materials Interface 5 (23) 1801018  2018/10 [Refereed][Not invited]
  • Ran Shi, Tao Lin Sun, Feng Luo, Tasuku Nakajima, Takayuki Kurokawa, Yue Zhen Bin, Michael Rubinstein, Jian Ping Gong
    Macromolecules 51 (21) 8887 - 8898 2018/10 [Refereed][Not invited]
  • Itamar Kolvin, John M. Kolinski, Jian Ping Gong, Jay Fineberg
    Physical Review Letters 121 (13) 135501  2018/09 [Refereed][Not invited]
  • Thanh-Tam Mai, Takahiro Matsuda, Tasuku Nakajima, Jian Ping Gong, Kenji Urayama
    Macromolecules 51 (14) 5245 - 5257 2018/07 [Refereed][Not invited]
  • Ping Rao, Tao Lin Sun, Liang Chen, Riku Takahashi, Gento Shinohara, Hui Guo, Daniel R. King, Takayuki Kurokawa, Jian Ping Gong
    Advanced Materials 30 (32) 1801884  2018/06 [Refereed][Not invited]
  • Ya Nan Ye, Martin Frauenlob, Lei Wang, Masumi Tsuda, Tao Lin Sun, Kunpeng Cui, Riku Takahashi, Huijie Zhang, Tasuku Nakajima, Takayuki Nonoyama, Takayuki Kurokawa, Shinya Tanaka, Jian Ping Gong
    Advanced Functional Materials 28 (31) 1801489  2018/06 [Refereed][Not invited]
  • 高強度・高靭性ダブルネットワークゲルの開発とソフト人工軟骨への応用
    野々山貴行, 龔 剣萍, 安田和則
    機能材料 38 (5) 51 - 59 2018/05 [Not refereed][Invited]
  • Riku Takahashi, Tao Lin Sun, Yoshiyuki Saruwatari, Takayuki Kurokawa, Daniel R. King, Jian Ping Gong
    Advanced Materials 30 (16) 1706885  1521-4095 2018/04/19 [Refereed][Not invited]
     
    Reinforcing hydrogels with a rigid scaffold is a promising method to greatly expand the mechanical and physical properties of hydrogels. One of the challenges of creating hydrogel composites is the significant stress that occurs due to swelling mismatch between the water-swollen hydrogel matrix and the rigid skeleton in aqueous media. This stress can cause physical deformation (wrinkling, buckling, or fracture), preventing the fabrication of robust composites. Here, a simple yet versatile method is introduced to create “macroscale” hydrogel composites, by utilizing a rigid reinforcing phase that can relieve stress-induced deformation. A low-melting-point alloy that can transform from a load-bearing solid state to a free-deformable liquid state at relatively low temperature is used as a reinforcing skeleton, which enables the release of any swelling mismatch, regardless of the matrix swelling degree in liquid media. This design can generally provide hydrogels with hybridized functions, including excellent mechanical properties, shape memory, and thermal healing, which are often difficult or impossible to achieve with single-component hydrogel systems. Furthermore, this technique enables controlled electrochemical reactions and channel-structure templating in hydrogel matrices. This work may play an important role in the future design of soft robots, wearable electronics, and biocompatible functional materials.
  • Yuji Higuchi, Keisuke Saito, Takamasa Sakai, Jian Ping Gong, Momoji Kubo
    MACROMOLECULES 51 (8) 3075 - 3087 0024-9297 2018/04 [Refereed][Not invited]
     
    Double-network (DN) gels consisting of highly and slightly cross linked networks exhibit good mechanical properties, complicated deformation behavior, and fracture processes owing to the existence of a large number of influential parameters. To determine the effects of these factors at the molecular level to improve the mechanical properties further, we studied the fracture processes of DN gels using a coarse-grained molecular dynamics simulation. First, we propose a modeling method for DN gels consisting of highly (first) and slightly (second) cross-linked networks. Then, we stretch the DN gels and investigate the effects of the network ratio, chain length, and first- and second-network structures on the mechanical properties. During the stretching, the stress increases with the bond breaking in the first network. Then, the stress further increases with the simultaneous bond breaking in the first and second networks when they are entangled with one another. Finally, the bond breaking in the first network stops, and only the bond breaking in the second network occurs. The second network remains at a high strain, which prevents rupture of the gel. We find that (i) a low concentration of the first network is necessary for the gel to exhibit the properties of both the first and second networks, (ii) a tense first network increases the Young's modulus, and (iii) the second network with a long chain length and separated cross linking points increases the peak stress and ductility. We have therefore successfully elucidated the effects of the network structures on the mechanical properties of DN gels.
  • Md. Tariful Islam Mredha, Yun Zhou Guo, Takayuki Nonoyama, Tasuku Nakajima, Takayuki Kurokawa, Jian Ping Gong
    Advanced Materials 30 (9) 1704937  1521-4095 2018/03/01 [Refereed][Not invited]
     
    Natural structural materials (such as tendons and ligaments) are comprised of multiscale hierarchical architectures, with dimensions ranging from nano- to macroscale, which are difficult to mimic synthetically. Here a bioinspired, facile method to fabricate anisotropic hydrogels with perfectly aligned multiscale hierarchical fibrous structures similar to those of tendons and ligaments is reported. The method includes drying a diluted physical hydrogel in air by confining its length direction. During this process, sufficiently high tensile stress is built along the length direction to align the polymer chains and multiscale fibrous structures (from nano- to submicro- to microscale) are spontaneously formed in the bulk material, which are well-retained in the reswollen gel. The method is useful for relatively rigid polymers (such as alginate and cellulose), which are susceptible to mechanical signal. By controlling the drying with or without prestretching, the degree of alignment, size of superstructures, and the strength of supramolecular interactions can be tuned, which sensitively influence the strength and toughness of the hydrogels. The mechanical properties are comparable with those of natural ligaments. This study provides a general strategy for designing hydrogels with highly ordered hierarchical structures, which opens routes for the development of many functional biomimetic materials for biomedical applications.
  • Md. Anamul Haque, Kei Mito, Takayuki Kurokawa, Tasuku Nakajima, Takayuki Nonoyama, Muhammad Ilyas, Jian Ping Gong
    ACS Omega 3 (1) 55 - 62 2470-1343 2018 [Refereed][Not invited]
     
    One-dimensional photonic crystals or multilayer films produce colors that change depending on viewing and light illumination angles because of the periodic refractive index variation in alternating layers that satisfy Bragg’s law. Recently, we have developed multilayered photonic hydrogels of two distinct bulk geometries that possess an alternating structure of a rigid polymeric lamellar bilayer and a ductile polyacrylamide (PAAm) matrix. In this paper, we focus on fabrication of composite gels with variable photonic band gaps by controlling the PAAm layer thickness. We report programmable angle-dependent and angle-independent structural colors produced by composite hydrogels, which is achieved by varying bulk and internal geometries. In the sheet geometry, where the lamellae are aligned parallel to the sheet surface, the photonic gel sheet exhibits strong angle-dependent colors. On the other hand, when lamellae are coaxially aligned in a cylindrical geometry, the gel rod exhibits an angle-independent color, in sharp contrast with the gel sheet. Rocking curves have been constructed to justify the diverse angle-dependent behavior of various geometries. Despite varying the bulk geometry, the tunable photonic gels exhibit strong mechanical performances and toughness. The distinct angle dependence of these tough photonic materials with variable band gaps could benefit light modulation in displays and sensor technologies.
  • Kazuki Fukao, Takayuki Nonoyama, Ryuji Kiyama, Kazuya Furusawa, Takayuki Kurokawa, Tasuku Nakajima, Jian Ping Gong
    ACS Nano 11 (12) 12103 - 12110 1936-086X 2017/12/26 [Refereed][Not invited]
     
    Bone tissues possess excellent mechanical properties such as compatibility between strength and flexibility and load bearing owing to the hybridization of organic/inorganic matters with anisotropic structure. To synthetically mimic such an anisotropic structure of natural organic/inorganic hybrid materials, we carried out hydroxyapatite (HAp) mineralization in stretched tough double network (DN) hydrogels. Anisotropic mineralization of HAp took place in stretched hydrogels, as revealed by high brightness synchrotron X-ray scattering and transmission electron microscopic observation. The c-axis of mineralized HAp aligned along the stretching direction, and the orientation degree S calculated from scattering profiles increased with increasing in the elongation ratio λ of the DN gel, and S at λ = 4 became comparable to that of rabbit tibial bones. The morphology of HAp polycrystal gradually changed from spherical to unidirectional rod-like shape with increased elongation ratio. A possible mechanism for the anisotropic mineralization is proposed, which would be one of the keys to develop mechanically anisotropic organic/inorganic hybrid materials.
  • Eiji Kamio, Tomoki Yasui, Yu Iida, Jian Ping Gong, Hideto Matsuyama
    ADVANCED MATERIALS 29 (47) 1704118  0935-9648 2017/12 [Refereed][Not invited]
     
    Highly robust ion gels, termed double-network (DN) ion gels, composed of inorganic/organic interpenetrating networks and a large amount of ionic liquids (ILs), are fabricated. The DN ion gels with an 80 wt% IL content show extraordinarily high mechanical strength: more than 28 MPa of compressive fracture stress. In the DN ion gel preparation, a brittle inorganic network of physically bonded silica nanoparticles and a ductile organic network of polydimethylacrylamide (PDMAAm) are formed in the IL. Because of the different reaction mechanisms of the inorganic/organic networks, the DN ion gels can be formed by an easy and free-shapeable one-pot synthesis. They can be prepared in a controllable manner by manipulating the formation order of the inorganic and organic networks via not only multistep but also single-step processes. When silica particles form a network prior to the PDMAAm network formation, DN ion gels can be prepared. The brittle silica particle network in the DN ion gel, serving as sacrificial bonds, easily ruptures under loading to dissipate energy, while the ductile PDMAAm network maintains the shape of the material by the rubber elasticity. Given the reversible physical bonding between the silica particles, the DN ion gels exhibit a significant degree of self-recovery by annealing.
  • ダブルネットワークゲル( DN ゲル)の軟骨応用に向けた検討
    野々山貴行, 中島祐, 黒川孝幸, 北村信人, 安田和則, 龔剣萍
    FC Report 35 (4) 148 - 152 2017/10 [Not refereed][Not invited]
  • Muhammad Ilyas, Md. Anamul Haque, Youfeng Yue, Takayuki Kurokawa, Tasuku Nakajima, Takayuki Nonoyama, Jian Ping Gong
    MACROMOLECULES 50 (20) 8169 - 8177 0024-9297 2017/10 [Refereed][Not invited]
     
    We study the effect of dehydration On the structure and mechanical properties of anisotropic lamellar hydrogels, consisting of alternative stacking of several thousands of nanoscale rigid bilayers from amphiphilic poly(dodecyl glyceryl itaconate) (PDGI) and submicroscale soft hydrogel layers from hydrophilic polyacrylamide (PAAm) networks. We found that the layered microstructure is well preserved with dehydration, and a ductile-brittle transition occurs at the critical water-content. This, transition is related to the rubbery-glassy transition of the PAAm layers, which occurs at 58 wt % water content and is much higher than 26 wt% of bulk PAAm hydrogels. Such specific behavior of the lamellar hydrogels indicates that the dynamics of the submicroscale PAAm hydrated layer intercalated between the rigid bilayers are very different from its bulk state.
  • Kei Mito, Md. Anamul Haque, Tasuku Nakajima, Maki Uchiumi, Takayuki Kurokawa, Takayuki Nonoyama, Jian Ping Gong
    POLYMER 128 373 - 378 0032-3861 2017/10 [Refereed][Invited]
     
    Novel, supramolecular, anisotropic hydrogels (called MC-PDGI gels) are presented in this study. These MC-PDGI gels consist of multi-cylindrical lipid bilayers aligned in a uniaxial manner and embedded in a soft hydrogel matrix. The bilayers and the hydrogel interact weakly due to hydrogen bonding. These MC-PDGI gels swell after exposure to water, which causes their volume and diameter to increase while simultaneously causing their length to decrease. This anisotropic swelling-induced contraction behavior is the result of competition between the isotropic elasticity of the hydrogel matrix and the interfacial tension of the lipid bilayers. Moreover, the MC-PDGI gels exhibit unique quasi one-dimensional diffusion behavior owing to the difficulty of molecular penetration through the multi-layered lipid bilayers. These materials would be useful for prolonged drug release or as an actuator. (C) 2017 Elsevier Ltd. All rights reserved.
  • Tao Lin Sun, Kunpeng Cui, Jian Ping Gong
    POLYMER SCIENCE SERIES C 59 (1) 11 - 17 1811-2382 2017/09 [Refereed][Invited]
     
    This article reviews the recently developed tough, self-recovery, and self-healing polyampholyte hydrogels. Polyampholyte hydrogels are synthesized using one-step radical copolymerization of cationic and anionic monomers with equal charges at high monomer concentration. The random copolymerization process makes the ionic monomers randomly distributing along the backbones, resulting in the formation of ionic bonds with a wide strength distribution via inter and intra chain complexation in the polymer network, weak bond and strong bonds. The strong bonds serve as permanent cross-linking, integrating the hydrogels to impart the elastic behavior, while the weak bonds can break upon the loading, dissipating energy to give the toughness, and re-form again after unloading to enable the self-recovery behavior. Accordingly, polyampholyte hydrogels have condensed polymers in water (ca 40-50 wt %). They are strongly viscoelastic and have a high toughness (fracture energy of 4000 J/m(2)), a wide range of tuning modulus (0.01 to 8 MPa), 100% self-recovery, and a high self-healing efficiency after cutting.
  • Md. Tariful Islam Mredha, Nobuto Kitamura, Takayuki Nonoyama, Susumu Wada, Keiko Goto, Xi Zhang, Tasuku Nakajima, Takayuki Kurokawa, Yasuaki Takagi, Kazunori Yasuda, Jian Ping Gong
    BIOMATERIALS 132 85 - 95 0142-9612 2017/07 [Refereed][Not invited]
     
    Soft supporting tissues in the human body, such as cartilages and ligaments, are tough materials and firmly fixed to bones. These soft tissues, once injured, cannot regenerate spontaneously in vivo. Developing tough and biocompatible hydrogels as artificial soft supporting tissues would substantially improve outcomes after soft tissue injury. Collagen is the main rigid component in soft connective tissues which is organized in various hierarchical arrays. We have successfully developed a novel class of collagen fibril-based tough hydrogels based on the double network (DN) concept using swim bladder collagen (SBC) extracted from Bester sturgeon fish. The DN hydrogels, SBC/PDMAAm, are composed of physically/chemically crosslinked anisotropic SBC fibril as the first network and neutral, biocompatible poly(N,N'-dimethylacrylamide) (PDMAAm) as the second network. The anisotropic structure of SBC fibril network, which is well retained in the DN hydrogels, is formed by free injection method, taking advantage of the excellent fibrillogenesis capacity of SBC. The denaturation temperature of collagen is improved in the DN hydrogels. These DN gels possess anisotropic swelling behavior, exhibit excellent mechanical properties comparable to natural cartilage. The 4 weeks implantation of the gels in the osteochondral defect of rabbit knee also shows excellent biomechanical performance in vivo. Furthermore, the hydroxyapatite (HAp) coated DN gels, HAp/SBC/PDMAAm gels, strongly bond to bone after 4 weeks. This new class of collagen-based hybrid DN gels, as soft and elastic ceramics, having good biomechanical performance and strong bonding ability with bone would expand the choice for designing next generation orthopedic implants such as artificial cartilage, bone defect repair material in the load bearing region of the body. (C) 2017 Elsevier Ltd. All rights reserved.
  • Kotaro Higa, Nobuto Kitamura, Keiko Goto, Takayuki Kurokawa, Jian Ping Gong, Fuminori Kanaya, Kazunori Yasuda
    BMC MUSCULOSKELETAL DISORDERS 18 210  1471-2474 2017/05 [Refereed][Not invited]
     
    Background: There has been increased interest in one-step cell-free procedures to avoid the problems related to cell manipulation and its inherent disadvantages. We have studied the chondrogenic induction ability of a PAMPS/PDMAAm double-network (DN) gel and found it to induce chondrogenesis in animal osteochondral defect models. The purpose of this study was to investigate whether the healing process and the degree of cartilage regeneration induced by the cell-free method using DN gel are influenced by the size of osteochondral defects. Methods: A total of 63 mature female Japanese white rabbits were used in this study, randomly divided into 3 groups of 21 rabbits each. A 2.5-mm diameter osteochondral defect was created in the femoral trochlea of the patellofemoral joint of bilateral knees in Group I, a 4.3-mm osteochondral defect in Group II, and a 5.8-mm osteochondral defect in Group III. In the right knee of each animal, a DN gel plug was implanted so that a vacant space of 2-mm depth was left above the plug. In the left knee, we did not conduct any treatment to obtain control data. Animals were sacrificed at 2, 4, and 12 weeks after surgery, and gross and histological evaluations were made. Results: The present study demonstrated that all sizes of the DN gel implanted defects as well as the 2.5mm untreated defects showed cartilage regeneration at 4 and 12 weeks. The 4.3-mm and 5.8-mm untreated defects did not show cartilage regeneration during the 12-week period. The quantitative score reported by O'Driscoll et al. was significantly higher in the 4.3-mm and 5.8-mm DN gel-implanted defects than the untreated defects at 4 and 12 weeks (p < 0.05). The 2.5-mm and 4.3-mm DN gel implanted defects maintained relatively high macroscopic and histological scores for the 12-week implantation period, while the histological score of the 5.8-mm DN gel implanted defect had decreased somewhat but statistically significantly at 12 weeks (p = 0.0057). Conclusions: The DN gel induced cartilage regeneration in defects between 2.5 and 5.8 mm, offering a promising device to establish a cell-free cartilage regeneration therapy and applicable to various sizes of osteochondral defects.
  • Feng Luo, Tao Lin Sun, Tasuku Nakajima, Takayuki Kurokawa, Xufeng Li, Honglei Guo, Yiwan Huang, Huijie Zhang, Jian Ping Gong
    POLYMER 116 487 - 497 0032-3861 2017/05 [Refereed][Invited]
     
    Tough hydrogels with adjustable stiffness are expected for adapting application as various biomaterials. Oppositely charged polyelectrolytes form tough and self-healing physical polyion-complex (PIC) hydrogels via formation of inter-chain ionic bonds with a wide distribution in bond strength. The strong bonds serve as permanent crosslinking to impart elasticity and the weak bonds as reversible sacrificial bonds to dissipate energy and to self-heal. In this work, we fabricate four PIC hydrogels using four positively charged trimethyl-ammonium monomers with slightly different chemical moieties and a same negatively charged polymer. The obtained PIC hydrogels all show high toughness but large difference in stiffness, extensibility, and self-recovery kinetics. With slight difference in the monomer structure of the polycations, the modulus of the hydrogels varies over two orders in magnitude, from 0.36 to 56 MPa, and the difference in elongation at break is up to five times. The presence of acryloyl moiety and methyl moiety increase the stiffness of the hydrogels. In the temperature range studied, all the four PIC hydrogels exhibit the rheological simple behaviours, following the time-temperature superposition principle. The four samples show quite different dynamic relaxation spectra over wide frequency range, revealing large difference in the strength distribution of dynamic ionic bonds. SEM observation reveals quite different phase separation structure for the four samples, in which the polymer chain stiffness should play an important role. This understanding of structure-properties of the PIC hydrogels will merit the designing of various supramolecular tough hydrogels and therefore broaden the scope of hydrogels for the applications as biomaterials. (C) 2017 Elsevier Ltd. All rights reserved.
  • Tao Lin Sun, Feng Luo, Wei Hong, Kunpeng Cui, Yiwan Huang, Hui Jie Zhang, Daniel R. King, Takayuki Kurokawa, Tasuku Nakajima, Jian Ping Gong
    MACROMOLECULES 50 (7) 2923 - 2931 0024-9297 2017/04 [Refereed][Not invited]
     
    Recently, many tough and self-healing hydro gels have been developed based on physical bonds as reversible sacrificial bonds. As breaking and re-forming of physical bonds are time-dependent, these hydrogels are viscoelastic and the deformation rate and temperature pronouncedly influence their fracture behavior. Using a polyampholyte hydrogel as a model system, we observed that the time temperature superposition principle is obeyed not only for the small strain rheology but also for the large strain hysteresis energy dissipation and the fracture energy below a certain temperature. The three processes possess the same shift factors that obey the equation of Williams, Landel, and Ferry (WLF) time temperature equivalence. The fracture energy F scales with the crack velocity V-c over a wide velocity range as Gamma similar to V-c(alpha) (alpha = 0.21). The exponent alpha of the power law is well-related to the exponent kappa of the relaxation modulus G(t) similar to t(-kappa) (kappa = 0.26), obeying the prediction alpha = kappa/(1 + kappa) from classic viscoelasticity theory. These results show that the fracture energy of the polyampholyte gel is dominated by the bulk viscoelastic energy dissipated around the crack tip. This investigation gives an insight into designing tough and self-healing hydrogels and predicting their fracture behaviors from their dynamic mechanical spectrum.
  • Yiwan Huang, Daniel R. King, Tao Lin Sun, Takayuki Nonoyama, Takayuki Kurokawa, Tasuku Nakajima, Jian Ping Gong
    ADVANCED FUNCTIONAL MATERIALS 27 (9) 1605350  1616-301X 2017/03 [Refereed][Not invited]
     
    Tough hydrogels have shown strong potential as structural biomaterials. These hydrogels alone, however, possess limited mechanical properties (such as low modulus) when compared to some load-bearing tissues, e.g., ligaments and tendons. Developing both strong and tough soft materials is still a challenge. To overcome this obstacle, a new material design strategy has been recently introduced by combining tough hydrogels with woven fiber fabric to create fiber reinforced soft composites (FRSCs). The new FRSCs exhibit extremely high toughness and tensile properties, far superior to those of the neat components, indicating a synergistic effect. Here, focus is on understanding the role of energy dissipation of the soft matrix in the synergistic toughening of FRSCs. By selecting a range of soft matrix materials, from tough hydrogels to weak hydrogels and even a commercially available elastomer, the toughness of the matrix is determined to play a critical role in achieving extremely tough FRSCs. This work provides a good guide toward the universal design of soft composites with extraordinary fracture resistance capacity.
  • Tasuku Nakajima, Kenta Hiwatashi, Jian Hu, Takayuki Kurokawa, Jian Ping Gong
    KOBUNSHI RONBUNSHU 74 (4) 311 - 318 0386-2186 2017 [Refereed][Invited]
     
    A gradient particle double network gel (P-DN gel) which exhibits unique conformation changes has been fabricated. A gradient P-DN gel consists of polyanion microgel particles with a concentration gradient and a poly(acrylamide) (PAAm) network as a matrix. In order to make the gradient structure, the gel precursor solution containing acrylamide, the microgel particles and some other additives was electrophoresed before its polymerization. When the gradient P-DN gel was soaked in pure water, it macroscopically formed a helical conformation due to a swelling mismatch induced by the gradient structure of the microgels. Moreover, when the gradient P-DN gel was immersed in an ethanol/water mixed solution and in a NaCl aqueous solution, the conformation of the gel dynamically changed to flat- and cylinder-shapes, respectively. These unique conformation changes can be qualitatively explained by considering not only the swelling mismatch but also an edge effect.
  • 刺激応答性構造色と異方的物性を示すリオトロピック液晶ゲル
    中島祐, 龔剣萍
    液晶 20 (4) 212 - 217 2016/10 [Refereed][Invited]
  • Susumu Wada, Nobuto Kitamura, Takayuki Nonoyama, Ryuji Kiyama, Takayuki Kurokawa, Jian Ping Gong, Kazunori Yasuda
    ACTA BIOMATERIALIA 44 125 - 134 1742-7061 2016/10 [Refereed][Not invited]
     
    We have developed a novel hydroxyapatite (HAp)-coated double-network (DN) hydrogel (HAp/DN gel). The purpose of this study was to determine details of the cell and tissue responses around the implanted HAp/DN gel and to determine how quickly and strongly the HAp/DN gel bonds to the bone in a rabbit osteochondral defect model. Immature osteoid tissue was formed in the space between the HAp/DN gel and the bone at 2 weeks, and the osteoid tissue was mineralized at 4 weeks. The push-out load of the HAp/DN gel averaged 37.54 N and 42.15 N at 4 and 12 weeks, respectively, while the push-out load of the DN gel averaged less than 5 N. The bonding area of the HAp/DN gel to the bone was above 80% by 4 weeks, and above 90% at 12 weeks. This study demonstrated that the HAp/DN gel enhanced osseointegration at an early stage after implantation. The presence of nanoscale structures in addition to osseointegration of HAp promoted osteoblast adhesion onto the surface of the HAp/DN gel. The HAp/DN gel has the potential to improve the implant-tissue interface in next-generation orthopaedic implants such as artificial cartilage. Statement of Significance Recent studies have reported the development of various hydrogels that are sufficiently tough for application as soft supporting tissues. However, fixation of hydrogels on bone surfaces with appropriate strength is a great challenge. We have developed a novel, tough hydrogel hybridizing hydroxyapatite (HAp/DN gel), which is directly bondable to the bone. The present study demonstrated that the HAp/DN gel enhanced osseointegration in the early stage after implantation. The presence of nanoscale structures in addition to the osseointegration ability of hydroxyapatite promoted osteoblast adhesion onto the surface of the HAp/DN gel. The HAp/DN gel has the potential to improve the implant-tissue interface in next-generation orthopaedic implants such as artificial cartilage. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Daisuke Inoue, Takahiro Nitta, Arif Md. Rashedul Kabir, Kazuki Sada, Jian Ping Gong, Akihiko Konagaya, Akira Kakugo
    NATURE COMMUNICATIONS 7 12557  2041-1723 2016/10 [Refereed][Not invited]
     
    Studying mechanical deformation at the surface of soft materials has been challenging due to the difficulty in separating surface deformation from the bulk elasticity of the materials. Here, we introduce a new approach for studying the surface mechanical deformation of a soft material by utilizing a large number of self-propelled microprobes driven by motor proteins on the surface of the material. Information about the surface mechanical deformation of the soft material is obtained through changes in mobility of the microprobes wandering across the surface of the soft material. The active microprobes respond to mechanical deformation of the surface and readily change their velocity and direction depending on the extent and mode of surface deformation. This highly parallel and reliable method of sensing mechanical deformation at the surface of soft materials is expected to find applications that explore surface mechanics of soft materials and consequently would greatly benefit the surface science.
  • Kotaro Higa, Nobuto Kitamura, Takayuki Kurokawa, Keiko Goto, Susumu Wada, Takayuki Nonoyama, Fuminori Kanaya, Kazuyuki Sugahara, Jian Ping Gong, Kazunori Yasuda
    ACTA BIOMATERIALIA 43 38 - 49 1742-7061 2016/10 [Refereed][Not invited]
     
    The purpose of this study was to clarify fundamental mechanical properties and biological responses of the sodium hyaluronate-containing double network (HA-DN) gel and chondroitin sulfate-containing double network (CS-DN) gel, which were newly developed using the molecular stent method. This study discovered the following facts. First, these hydrogels had high mechanical performance comparable to the native cartilage tissue, and the mechanical properties were not affected by immersion in the saline solution for 12 weeks. Secondly, the mechanical properties of the CS-DN gel were not significantly reduced at 12 weeks in vivo, while the mechanical properties of the HA-DN gel were significantly deteriorated at 6 weeks. Thirdly, the degree of inflammation around the HA-DN gel was the same as that around the negative control. The CS-DN gel showed a mild but significant foreign body reaction, which was significantly greater than the negative control and less than the positive control at 1 week, while the inflammation was reduced to the same level as the negative control at 4 and 6 weeks. Fourthly, these gels induced differentiation of the ATDC5 cells into chondrocytes in the culture with the insulin free maintenance medium. These findings suggest that these tough hydrogels are potential biomaterials for future application to therapeutic implants such as artificial cartilage. Statement of Significance The present study reported fundamental biomaterial properties of the sodium hyaluronate-containing double network (HA-DN) gel and chondroitin sulfate-containing double network (CS-DN) gel, which were newly developed using the molecular stent method. Both the HA- and CS-DN gels had high mechanical properties comparable to the cartilage tissue and showed the ability to induce chondrogenic differentiation of ATDC5 cells in vitro. They are potential biomaterials that may meet the requirements of artificial cartilage concerning the material properties. Further, these DN gels can be also applied to the implantable inducer for cell-free cartilage regeneration therapy. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Nobuto Kitamura, Masashi Yokota, Takayuki Kurokawa, Jian Ping Gong, Kazunori Yasuda
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 104 (9) 2159 - 2165 1549-3296 2016/09 [Refereed][Not invited]
     
    The purpose of this study was to establish the efficacy of a therapeutic strategy for an articular cartilage defect using a poly-(2-acrylamido-2-methylpropanesulfonic acid)/poly-(N,N'-dimethyl acrylamide) DN gel in a sheep model. Seventeen mature sheep were used in this study. We created a 6.0-mm osteochondral defect in the femoral trochlea of the patellofemoral (PF) joint and the medial condyle of the tibiofemoral (TF) joint. A cylindrical DN gel plug was implanted into the defect of the right knee so that a vacant space of the planned depths of 2.0 mm in group I, 3.0 mm in group II, and 4.0 mm in group III were left. In the left knee, we created a defect with the same depth as the right knee. The regenerated tissues were evaluated with the O'Driscoll score and real-time PCR analysis of the cartilage marker genes at 12 weeks. The DN gel implanted defect of group II in the PF and TF joints was completely filled with a sufficient volume of the proteoglycan-rich tissue stained with Safranin-O. The score showed that group II was significantly greater than groups I and III when treated with DN gel in the PF joint (p=0.0441, p=0.0174, respectively) and in the TF joint (p=0.0019, p=0.0006, respectively). This study has clarified the short-term efficacy of the cartilage regeneration strategy using the DN gel in a sheep model. (c) 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2159-2165, 2016.
  • Sadia Nazneen Karobi, Tao Lin Sun, Takayuki Kurokawa, Feng Luo, Tasuku Nakajima, Takayuki Nonoyama, Jian Ping Gong
    MACROMOLECULES 49 (15) 5630 - 5636 0024-9297 2016/08 [Refereed][Not invited]
     
    Polyampholyte (PA) hydrogels are a new class of tough and selfhealing supramolecular hydrogels that have a potential as load-bearing soft materials. Studying on the creep behavior of these hydrogels and understanding the molecular mechanism are important for prediction of lifetime of the materials. In the present work, we study the creep rupture dynamics of the PA hydrogels with and without chemical cross-linking, in a certain observation time window. We have found that above some critical loading stress both physical and lightly chemically cross-linked hydrogels undergo creep rupture while moderately chemically cross-linked hydrogel resists creep flow. To elucidate the molecular mechanism, we have further compared the creep behaviors of the physical and lightly chemically cross-linked samples. The creep rate of the samples decreases with the creep time, following a power law relation, regardless of the loading stress variation. The fracture time of both of these hydrogels exponentially decreases with the increase of the loading stress, following the same master curve at high loading stress region, while the behavior of the two samples becomes different in the low loading stress region. We have explained the delayed fracture dynamics at high loading stress region in terms of a relatively weak strong bond rupture mechanism.
  • Takayuki Nonoyama, Susumu Wada, Ryuji Kiyama, Nobuto Kitamura, Md. Tariful Islam Mredha, Xi Zhang, Takayuki Kurokawa, Tasuku Nakajima, Yasuaki Takagi, Kazunori Yasuda, Jian Ping Gong
    ADVANCED MATERIALS 28 (31) 6740 - + 0935-9648 2016/08 [Refereed][Not invited]
     
    On implanting hydroxyapatite-mineralized tough hydrogel into osteochondral defects of rabbits, osteogenesis spontaneously penetrates into the gel matrix owing to the semi-permeablility of the hydrogel. The gradient layer (around 40 mu m thick) contributes quite strong bonding of the gel to bone. This is the first success in realizing the robust osteointegration of tough hydrogels, and the method is simple and feasible for practical use.
  • Ao-kai Zhang, Jun Ling, Kewen Li, Guo-dong Fu, Tasuku Nakajima, Takayuki Nonoyama, Takayuki Kurokawa, Jian Ping Gong
    JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 54 (13) 1227 - 1236 0887-6266 2016/07 [Refereed][Not invited]
     
    In this study, controlled amount of dangling ends is introduced to the two series of poly(ethylene glycol)-based hydrogel networks with three and four crosslinking functionality by using click chemistry. The structure of the gels with regulated defect percentage is confirmed by comparing the results of low-field NMR characterization and Monte Carlo simulation. The mechanical properties of these gels were characterized by tensile stress-strain behaviors of the gels, and the results are analyzed by Gent model and Mooney-Rivlin model. The shear modulus of the swollen gels is found to be dependent on the functionality of the network, and decreases with the defect percentage. Furthermore, the value of shear modulus well obeys the Phantom model for all the gels with varied percentage of the defects. The maximum extension ratio, obtained from the fitting of Gent model, is also found to be dependent on the functionality of the network, and does not change with the defect percentage, except at very high defect percentage. The value of the maximum extension ratio is between that predicted from Phantom model and the Affine model. This indicates that at the large deformation, the fluctuation of the crosslinking points is suppressed for some extend but still exists. Polymer volume fractions at various defect percentages obtained from prediction of Flory-Rehner model are found to be in well agreement with the swelling experiment. All these results indicate that click chemistry is a powerful method to regulate the network structure and mechanical properties of the gels. (C) 2016 Wiley Periodicals, Inc.
  • Abu Bin Ihsan, Tao Lin Sun, Takayuki Kurokawa, Sadia Nazneen Karobi, Tasuku Nakajima, Takayuki Nonoyama, Chanchal Kumar Roy, Feng Luo, Jian Ping Gong
    MACROMOLECULES 49 (11) 4245 - 4252 0024-9297 2016/06 [Refereed][Not invited]
     
    Recently, polyampolytes have been discovered to form hydrogels that possess high toughness, full resilience, and self-healing between two cut surfaces. The self-healing of this class of hydrogels is based on the re-forming of the multiple Tonic bonds at the fractured surfaces, in which the mobility of the polymer segments and strength of the ionic bonds play an important role. In this work, we study the effects of healing temperature and chemistry of the polyampholyte hydrogels (chemical cross -linker density and chemical structure of the monomers) on the healing kinetics and healing efficiency. The high healing temperature substantially accelerates the self-healing kinetics. Chemical cross-linking reduces the self-healing efficiency. Monomers with more hydrophobic feature give a low self-healing efficiency. For polyampholyte physical hydrogels with a softening temperature below the room temperature, excellent-healing efficiency (similar to 84% on average and maximum 99%) was observed without any external stimuli.- We found a correlation between the self-healing efficiency and the fraction of dynamic bonds in the total bonds for relatively soft samples, which is an evidence that the self healing is due to the re-forming of dynamic bonds.
  • Hui Jie Zhang, Tao Lin Sun, Ao Kai Zhang, Yumihiko Ikura, Tasuku Nakajima, Takayuki Nonoyama, Takayuki Kurokawa, Osamu Ito, Hiroyuki Ishitobi, Jian Ping Gong
    ADVANCED MATERIALS 28 (24) 4884 - 4890 0935-9648 2016/06 [Refereed][Not invited]
     
    A series of physical double-network hydrogels is synthesized based on an amphiphilic triblock copolymer. The gel, which contains strong hydrophobic domains and sacrificial dynamic bonds of hydrogen bonds, is stiff and tough, and even stiffens in concentrated saline solution. Furthermore, due to its supramolecular structure, the gel features improved self-healing and self-recovery abilities.
  • Riku Takahashi, Yumihiko Ikura, Daniel R. King, Takayuki Nonoyama, Tasuku Nakajima, Takayuki Kurokawa, Hirotoshi Kuroda, YoshihiroTonegawa, Jian Ping Gong
    Soft Matter 12 (23) 5063 - 5234 2016/04 [Refereed][Not invited]
  • Honglei Guo, Takayuki Kurokawa, Masakazu Takahata, Wei Hong, Yoshinori Katsuyama, Feng Luo, Jamil Ahmed, Tasuku Nakajima, Takayuki Nonoyama, Jian Ping Gong
    MACROMOLECULES 49 (8) 3100 - 3108 0024-9297 2016/04 [Refereed][Not invited]
     
    We report, for the first time, the quantitative measurement of the local electric potential of brittle polyelectrolyte hydrogels using the microelectrode technique (MET). Given the solid-like nature of the hydrogels, the difficulty of applying MET is how to make a good contact of the microelectrode to the hydrogel. Poor local contact substantial underestimates the potential. We observed that, the potential measured decays exponentially with the increase of capillary diameter of the microelectrode. This behavior is related to the capillary wall thickness that determines the contact distance of the electrode probe to the hydrogel. The characteristic decay length in respective to the wall thickness is very close to the local Debye length around the capillary. The latter is much larger than that of the bath solution due to the reverse osmosis effect. By using microelectrodes with a tip wall thickness less than the local Debye length, the Donnan potential of polyelectrolyte gel could be accurately measured. Using a micromanipulator, the inserting process of the microelectrode is precisely controlled, and the depth profile of electric potential in the hydrogels can be measured with a spatial resolution down to similar to 5 nm. From the spatial distribution of potential, the microstructure of hydrogels both in bulk and near the surface, the thickness of ultrathin hydrogels, and the heterogeneous layered structure of composite gels, can be determined accurately. The MET established in this work provides a powerful tool for direct characterization of the spatial distribution of electric potential of hydrogels.
  • Feng Luo, Tao Lin Sun, Tasuku Nakajima, Daniel R. King, Takayuki Kurokawa, Yu Zhao, Abu Bin Ihsan, Xufeng Li, Honglei Guo, Jian Ping Gong
    MACROMOLECULES 49 (7) 2750 - 2760 0024-9297 2016/04 [Not refereed][Not invited]
     
    Oppositely charged homopolyelectrolytes were found to form strong, tough, and self-healing polyion-complex (PIC) hydrogels, similar to polyampholytes (PA) which have opposite charges randomly distributed on the same polymer chains. The excellent mechanical performances of these two novel hydrogels are the results of dynamic ionic bonds formation between entangled polymer chains. For the PIC system, only interchain bonding occurs, while for the PA system both inter- and intrachain bonding exist. In addition, the ion pairs are expected to form stronger bonding in the PIC system than those in the PA system. In this work, we performed a comparative study of PIC hydrogels with the PA hydrogels. The PIC hydrogels are synthesized by sequential homopolymerization of cationic and anionic monomers at varied formulation, and their swelling and mechanical properties are systematically studied in comparison to the PA hydrogels that were synthesized from random copolymerization of anionic monomers and cationic monomers of the similar formulation. Different from the PA system which only forms tough hydrogels around zero net charge composition without chemical cross-linking, the PIC system forms tough physical hydrogels even at weakly off balanced charge composition. At the charge-balanced composition, the low entanglement concentration of homocharged polyelectrolyte chains leads to tough PIC hydrogels formation at much lower concentrations than that of PA hydrogels. As a result, the PIC hydrogels are much tougher than the PA hydrogels prepared at the same monomer composition. In similar to PA hydrogels, the PIC hydrogels also exhibit broad dynamic mechanical spectra, indicating the formation of ion complexes with widely ranged bond strength. The PIC hydrogels have strong viscoelasticity in comparison with PA hydrogels. However, the two systems show the similar activation energies of the dynamic mechanical spectra. The SEM microstructural observation shows that the PIC hydrogels have segregated structure while PA hydrogels are more homogeneous.
  • Takahiro Matsuda, Tasuku Nakajima, Yuki Fukuda, Wei Hong, Takamasa Sakai, Takayuki Kurokawa, Ung-il Chung, Jian Ping Gong
    MACROMOLECULES 49 (5) 1865 - 1872 0024-9297 2016/03 [Refereed][Not invited]
     
    Double network (DN) gels, consisting of a brittle first and flexible second network, have been known to be extremely tough and functional hydrogels. In a DN gel subjected to force, the brittle first network breaks prior to the fracture of the flexible network. This process, referred to as internal fracture, dissipates energy and increases the energy required to completely fracture DN gels. Such internal fracture macroscopically appears as a yielding-like phenomenon. The aim of this paper is to investigate the relationship between the yield point and the first network molecular structure of DN gels to more deeply understand the internal fracture mechanism of DN gels. To achieve this goal, we synthesized DN gels having a tetra-PEG first network, which is known to be a nearly ideal and well-controlled network gel. We have found that yielding of the DN gels occurs when the first network strands reach their extension limit (finite extensibility), regardless of their deformation mode. This conclusion not only helps by further understanding the toughening mechanism of DN gels but also allows for the design of DN gels with precisely controlled mechanical properties.
  • Keiko Goto, Taichi Kimura, Nobuto Kitamura, Shingo Semba, Yoshihiro Ohmiya, Sachiyo Aburatani, Satoko Matsukura, Masumi Tsuda, Takayuki Kurokawa, Jian Ping Gong, Shinya Tanaka, Kazunori Yasuda
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 104 (3) 734 - 746 1549-3296 2016/03 [Refereed][Not invited]
     
    The purposes of this study were to identify signaling pathways that were specifically activated in ATDC5 cells cultured on poly (2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) gel in insulin-free maintenance medium and to evaluate the significance of the determined signaling pathways in the chondrogenic differentiation induced by this gel. In this study, ATDC5 cells cultured on PAMPS gel using the maintenance medium without insulin (PAMPS Culture) were compared with cells cultured on polystyrene using the differentiation medium containing insulin (PS-I Culture). The microarray analysis, Western blot analysis, and real-time PCR analysis demonstrated that the TGF-/BMP signaling pathway was significantly enhanced at Days 1, 2, and 3 in the PAMPS Culture when compared with the PS-I Culture. Inhibition of the BMP type-I receptor reduced the phosphorylation level of Smad1/5 and expression of type-2 collagen and aggrecan mRNA in the cells accompanied by a reduction in cell aggregation at Day 13 in the PAMPS Culture. The inhibition of the TGF-/BMP signaling pathway significantly inhibited the chondrogenic differentiation induced by the PAMPS gel. The present study demonstrated that synthetic PAMPS gel activates the TGF-/BMP/Smad signaling pathway in the ATDC5 cells in the absence of insulin, and that this activation plays a significant role in the chondrogenic differentiation induced by PAMPS gel. (c) 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 734-746, 2016.
  • Kunpeng Cui, Tao Lin Sun, Takayuki Kurokawa, Tasuku Nakajima, Takayuki Nonoyama, Liang Chen, Jian Ping Gong
    SOFT MATTER 12 (43) 8833 - 8840 1744-683X 2016 [Refereed][Not invited]
     
    Recently, we have developed a series of charge balanced polyampholyte (PA) physical hydrogels by random copolymerization in water, which show extraordinarily high toughness, self-healing ability and viscoelasticity. The excellent performance of PA hydrogels is ascribed to dynamic ionic bond formation through inter-and intra-chain interactions. The randomness results in ionic bonds of wide strength distribution, the strong bonds, which serve as permanent crosslinking, imparting the elasticity, while the weak bonds reversibly break and re-form, dissipating energy. In this work, we developed a simple physical method, called a pre-stretching method, to promote the performance of PA hydrogels. By imposing a pre-stretching on the sample in the as-prepared state, ion complexation during dialysis is prominently accelerated and the final performance is largely promoted. Further analysis suggests that the strong bond formation induced by pre-stretching is responsible for the change in final performance. Pre-stretching decreases the entropy of the system and increases the chain alignment, resulting in an increased possibility for strong bond formation.
  • Youfeng Yue, Xufeng Li, Takayuki Kurokawa, Md. Anamul Haque, Jian Ping Gong
    JOURNAL OF MATERIALS CHEMISTRY B 4 (23) 4104 - 4109 2050-750X 2016 [Refereed][Not invited]
     
    This work developed a photonic hydrogel that is responsive to, and can distinguish between two stimuli of stress and pH. Patterning is used to locally change the chemistry of a one-dimensional (1D) photonic gel, such that the native region is responsive to mechanical stress while the chemically modified region is responsive to both mechanical stress and pH. By combining the optical signals in the native region and the modified region, one can distinguish the stimuli between pH and stress. Specifically, the native 1D photonic gel is composed of periodically aligned polymeric bilayers in a soft polyacrylamide (PAAm) network. The chemical modification is done by partially hydrolyzing PAAm into sodium polyacrylic acid in some patterned regions, which imparts pH sensitivity, in addition to the stress sensitivity, to these regions.
  • 水戸京, 中島祐, 野々山貴行, 龔剣萍
    高分子論文集 73 2016/01 [Refereed][Invited]
  • Takayuki Nonoyama, Jian Ping Gong
    PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART H-JOURNAL OF ENGINEERING IN MEDICINE 229 (12) 853 - 863 0954-4119 2015/12 [Refereed][Invited]
     
    Double-network hydrogels are one of the most promising candidates as artificial soft supporting tissues owing to their excellent mechanical performance, water storage capability, and biocompatibility. A double-network hydrogel consists of two contrasting polymer networks: rigid and brittle first network and soft and ductile second network. To satisfy this double-network requirement, polyelectrolyte and neutral polymer are suitable as the first and the second networks, respectively. Combination of these two networks gives rise to extraordinarily tough double-network hydrogel as a result of substantial internal fracture of the brittle first network at large deformation, which contributes to the energy dissipation. Therefore, the first network serves as the sacrificial bonds to toughen the material. The double-network principle is universal and many kinds of double-network hydrogels composed of various chemical species have been developed. Moreover, a molecular stent technology has been developed to synthesize the double-network hydrogels using neutral polymer network as the brittle first network. The sulfonic double-network hydrogel was found to induce spontaneous hyaline cartilage regeneration in vivo.
  • Chanchal Kumar Roy, Hong Lei Guo, Tao Lin Sun, Abu Bin Ihsan, Takayuki Kurokawa, Masakazu Takahata, Takayuki Nonoyama, Tasuku Nakajima, Jian Ping Gong
    ADVANCED MATERIALS 27 (45) 7344 - + 0935-9648 2015/12 [Refereed][Not invited]
     
    Developing nonspecific, fast, and strong adhesives that can glue hydrogels and biotissues substantially promotes the application of hydrogels as biomaterials. Inspired by the ubiquitous adhesiveness of bacteria, it is reported that neutral polyampholyte hydrogels, through their self-adjustable surface, can show rapid, strong, and reversible adhesion to charged hydrogels and biological tissues through the Coulombic interaction.
  • Koshiro Sato, Tasuku Nakajima, Toshiyuki Hisamatsu, Takayuki Nonoyama, Takayuki Kurokawa, Jian Ping Gong
    ADVANCED MATERIALS 27 (43) 6990 - + 0935-9648 2015/11 [Refereed][Not invited]
     
    Novel, tough, strong, and self-healable polyacrylamide (PAAm) gels are fabricated by inducing an appropriate phase-separation structure using a poor solvent. The phase separation induces a gel-glass-like transition of the PAAm gels, providing the gels an anomalously high modulus (211 MPa), fracture stress (7.13 MPa), and fracture energy (4.16 x 10(4) J m(-2)), while keeping a high solvent content (approximate to 60 vol%).
  • Daniel R. King, Tao Lin Sun, Yiwan Huang, Takayuki Kurokawa, Takayuki Nonoyama, Alfred J. Crosby, Jian Ping Gong
    MATERIALS HORIZONS 2 (6) 584 - 591 2051-6347 2015/11 [Refereed][Not invited]
     
    Ligaments are unique wet biological tissues with high tensile modulus and fracture stress, combined with high bending flexibility. Developing synthetic materials with these properties is a significant challenge. Hydrogel composites made from high stiffness fabrics is a strategy to develop such unique materials; however, the ability to produce these materials has proven difficult, since common hydrogels swell in water and interact poorly with solid components, limiting the transfer of force from the fabric to the hydrogel matrix. In this work, for the first time, we successfully produce extraordinarily tough hydrogel composites by strategically selecting a recently developed tough hydrogel that de-swells in water. The new composites, consisting of polyampholyte hydrogels and glass fiber woven fabrics, exhibit extremely high effective toughness (250 000 J m(-2)), high tear strength (similar to 65 N mm(-1)), high tensile modulus (606 MPa), and low bending modulus (4.7 MPa). Even though these composites are composed of water-containing, biocompatible materials, their mechanical properties are comparable to high toughness Kevlar/polyurethane blends and fiber-reinforced polymers. Importantly, the mechanical properties of these composites greatly outperform the properties of either individual component. A mechanism is proposed based on established fabric tearing theory, which will enable the development of a new generation of mechanically robust composites based on fabrics. These results will be important towards developing soft biological prosthetics, and more generally for commercial applications such as tear-resistant gloves and bulletproof vests.
  • Kazuhiro Shikinaka, Manami Misu, Hidemitsu Furukawa, Akira Kakugo, Jian Ping Gong
    MACROMOLECULAR CHEMISTRY AND PHYSICS 216 (20) 2007 - 2011 1022-1352 2015/10 [Refereed][Not invited]
     
    In this paper, the hydrogel is created with oriented structure by addition of very little amount of dopant, filamentous actin (F-actin), which is 1/50 000 of lower critical concentration for nematic phase in F-actin aqueous solution. The orientation mechanism of polymer network differs depending on the concentration of F-actin. Furthermore, it is first exhibited that the role of polyelectrolyte for the emergence of anisotropy of gel is differed depending on its concentration by using digestion method to F-actins, experimentally.
  • Feng Luo, Tao Lin Sun, Tasuku Nakajima, Takayuki Kurokawa, Abu Bin Ihsan, Xufeng Li, Honglei Guo, Jian Ping Gong
    ACS MACRO LETTERS 4 (9) 961 - 964 2161-1653 2015/09 [Refereed][Not invited]
     
    Tough hydrogels with facile processability to reform into various shapes are required in many practical applications. In this work, we reported that a novel, tough, and self-healing physical hydrogel based on polyion complex (PIC) can be dissolved in 4 M NaCl solution to form a PIC solution. The PIC solution can be easily reprocessed into various shapes, such as thin films, sheets, fibers, and capsules, by using simple methods, such as casting and injection, while maintaining excellent mechanical properties comparable to, or even better than, the original hydrogel. The reprocessability and robust mechanical properties of PIC hydrogels are promising for practical applications in soft materials, especially in 3D/4D printing technology.
  • 皮膚を規範とした革新的機能材料・ラメラ構造を有するハイドロゲルの構造色と強靭性
    黒川 孝幸, ムハンマド アナムル ハック, 龔 剣萍
    工業材料 63 (8) 64 - 68 2015/08 [Not refereed][Invited]
  • Jamil Ahmed, Tetsurou Yamamoto, Honglei Guo, Takayuki Kurokawa, Takayuki Nonoyama, Tasuku Nakajima, Jian Ping Gong
    MACROMOLECULES 48 (15) 5394 - 5401 0024-9297 2015/08 [Refereed][Not invited]
     
    A simplified model describing the sliding friction of hydrogel on solid surface by dynamic adsorption of the polymer chains is proposed on the basis of polymer adsorption-repulsion theory. This dynamic adsorption model is used to analyze the friction results of zwitterionic hydrogels sliding over glass substrates with different substrate wettability, hydrogel swelling degree, ionic strength, and pH of bath solution. The adsorption time tau(b) of polymer strands is found to decrease with the increase in sliding velocity or the Weissenberg number as a result of stretching. The adsorption time tau(0)(b), and the adsorption energy U-ads at stress-free condition, which are characteristic for each friction system, are also estimated. Roughly, a master curve is observed for the normalized adsorption lifetime tau(b)/tau(0)(b) and the Weissenberg number, with less dependence on the adsorption energy and the bulk properties of the gels in the observed experimental conditions. Thus, the dynamic adsorption model successfully correlates the frictional behavior of hydrogels with the adsorption dynamics of polymer strands, which gives insight into the molecular design of hydrogels with predefined frictional properties for biomedical applications.
  • Arif Md Rashedul Kabir, Daisuke Inoue, Yuri Kishimoto, Jun-ichi Hotta, Keiji Sasaki, Noboru Kitamura, Jian Ping Gong, Hiroyuki Mayama, Akira Kakugo
    POLYMER JOURNAL 47 (8) 564 - 570 0032-3896 2015/08 [Refereed][Not invited]
     
    The lack of a suitable experimental setup and a limited number of in vitro investigations have impeded understanding of the factors that have important roles in altering the drag force acting on tiny microobjects in a fluidic medium. Here we investigated how the surface morphology affects the drag force acting on microparticles. The drag coefficient for micron-sized polymer-grafted polystyrene (PS) and negatively charged hard (silica) and soft (hydrogel) spheres were evaluated and compared with that of a PS particle. The drag coefficient of the PS particle was found to be comparable to that predicted according to the Stokes' formula for a hard sphere. By contrast, polymer-grafted PS and negatively charged hard and soft spheres showed a considerable deviation from the Stokes' formula. The drag coefficient decreased by similar to 60 and similar to 86% for the negatively charged hard and soft spheres, respectively, whereas it increased by similar to 20% for the polymer-grafted PS particles with respect to that of the PS particle. This work reveals the role of the surface morphology of small objects in altering the drag force acting on them; such knowledge may help elucidate the mechanism by which the surface morphology of aquatic microorganisms helps them to control the drag force, which consequently might facilitate the invention of new technologies for micromachines or microdevices.
  • Youfeng Yue, Jian Ping Gong
    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 23 45 - 67 1389-5567 2015/06 [Refereed][Invited]
     
    Photonic crystals are periodic dielectric nanostructures that can affect the propagation of light. Polymer-based photonic crystals have attracted great attentions for their potential application as sensors or optical switches due to their stimuli-responsive properties. This review summarizes the recent developments in one-dimensional (1-D) polymer-based photonic crystals, including the inspiration of the material from nature, principles for design and fabrication, mechanism of color tuning, and their tunable structural color in responsive to various stimuli. A number of fabrication methods, either by bottom-up or top-down approaches for 1-D polymeric photonic crystals have been overviewed. (C) 2015 Elsevier B.V. All rights reserved.
  • 高強度ゲルをつくる
    中島祐, 龔剣萍
    高分子 64 (6) 367 - 369 2015/05 [Not refereed][Invited]
  • Feng Luo, Tao Lin Sun, Tasuku Nakajima, Takayuki Kurokawa, Yu Zhao, Koshiro Sato, Abu Bin Ihsan, Xufeng Li, Honglei Guo, Jian Ping Gong
    ADVANCED MATERIALS 27 (17) 2722 - + 0935-9648 2015/05 [Refereed][Not invited]
     
    A series of tough polyion complex hydrogels is synthesized by sequential homopolymerization of cationic and anionic monomers. Owing to the reversible interpolymer ionic bonding, the materials are self-healable under ambient conditions with the aid of saline solution. Furthermore, self-glued bulk hydrogels can be built from their microgels, which is promising for 3D/4D printing and the additive manufacturing of hydrogels.
  • Jing Jing Yang, Jian Fang Liu, Takayuki Kurokawa, Kazuhiro Kitada, Jian Ping Gong
    Journal of Tissue Engineering and Regenerative Medicine 9 (4) 332 - 342 2015/04 [Refereed][Not invited]
  • Xufeng Li, Takayuki Kurokawa, Riku Takahashi, Md. Anamul Haque, Youfeng Yue, Tasuku Nakajima, Jan Ping Gong
    MACROMOLECULES 48 (7) 2277 - 2282 0024-9297 2015/04 [Refereed][Not invited]
     
    We report that polymers can support bilayer membranes to form physical hydrogels of self-healing and tunable isotropic/anisotropic structure. The system consists of poly(dodecyl glyceryl itaconate) (PDGI) which forms lamellar bilayers and polyacrylamide (PAAm) which adsorbs on the bilayer surfaces via hydrogen bond formation. Adsorption of PAAm brings two effects: disturbs the bilayer packing and causes bending of the bilayers; increases the effective thickness of the bilayers and enhances the repulsion between the bilayers due to excluded volume effect. Competition of these two effects brings about sharp superstructure transition from isotropic multilayer foam phase to unidirectionally aligned lamellar phase. Accompanied by this structure transition, the bulk hydrogel exhibits isotropic/anisotropic swelling. The physical gels exhibit high tensile strength and self-healing properties that can be understood by the sacrificial bonds mechanism.
  • 小さな力で多彩な色をだす構造色ゲル―新しいメカノクロミック材料の合成法とその応用
    Tasuku Nakajima, Jian Ping Gong
    化学 70 (4) 32 - 36 2015/03 [Not refereed][Invited]
  • Wen Jiang Zheng, Zhen Qi Liu, Feng Xu, Jie Gao, Yong Mei Chen, Jian Ping Gong, Yoshihito Osada
    MACROMOLECULAR CHEMISTRY AND PHYSICS 216 (6) 641 - 649 1022-1352 2015/03 [Refereed][Not invited]
     
    Nowadays, tough double-network (DN) hydrogels have attracted great attention owing to their excellent mechanical properties and good biocompatibility, which give them the potential to be used as blood-contacting soft tissue prostheses and medical devices. However, the study of platelet adhesion behavior on the surface of DN hydrogels has not been reported yet. In this work, the human platelet adhesion on the surface of poly (sodium 2-acrylamido-2-methyl-propanesulfonate) PNaAMPS/poly acrylamide (PAAm) and PNaAMPS/poly (N,N-dimethylacrylamide) (PDMAAm) DN hydrogels is investigated under static conditions in vitro. The numbers of adherent platelets on PNaAMPS/PAAm and PNaAMPS/PDMAAm hydrogels are 16 +/- 7 and 9 +/- 8 cells per 10(4) m(2), respectively, which are far less than 297 +/- 41 cells per 10(4) m(2) on polyethylene terephthalate (PET) and 187 +/- 26 cells per 10(4) m(2) on negatively charged PNaAMPS (4 mol%) hydrogel. The results indicate the excellent antiplatelet performance of DN hydrogels. Moreover, the platelet adhesion mechanism is also discussed. The platelet adhesion is affected by the chemical component, zeta potential, and serum proteins adsorption of the hydrogel.
  • Tao Lin Sun, Feng Luo, Takayuki Kurokawa, Sadia Nazneen Karobi, Tasuku Nakajima, Jian Ping Gong
    SOFT MATTER 11 (48) 9355 - 9366 1744-683X 2015 [Refereed][Not invited]
     
    Recently, charge balanced polyampholytes (PA) have been found to form tough and self-healing hydrogels. This class of physical hydrogels have a very high equilibrated polymer concentration in water (ca. 40-50 wt%), and are strongly viscoelastic. They are synthesized by random copolymerization of equal amounts of oppositely charged monomers at a high concentration, followed by a dialysis process of the small counter-ions and co-ions in water. The randomly distributed, opposite charges of the polymer form multiple ionic bonds of intra-and inter-chains with strength distribution. The strong interchain bonds, stabilized by topological entanglement, serve as quasi-permanent crosslinks, imparting the elasticity, while the weak bonds, both inter-and intra-chains, reversibly break and re-form to dissipate energy to toughen the materials. In this work, we intend to clarify the structure of the physical PA hydrogels from the tensile behaviors of the PA hydrogels. To clarify the structure and its formation mechanism, we analysed the tensile behaviors of the samples before and after the dialysis. We separated the quasi-permanent crosslinking of strong inter-chain bonds and the dynamic crosslinking of weak inter-chain bonds by using a combined model that consists of the Upper Convected Maxwell model and the Gent strain hardening model. The model fitting of the tensile behaviors extracts quantitative structural parameters, including the densities of weak and strong inter-chain bonds and the theoretical finite extensibility of polymer chains. Based on the fitting results of the combined model, the structural parameters of partial chains at a fixed observation time, including the Kuhn number, Kuhn length, and chain conformation, are determined using the scaling theory. The effects of monomer concentration at preparation, the effect of dialysis and the initial strain rate on the dynamic structure of PA gels, are discussed based on these analyses.
  • Md. Tariful Islam Mredha, Xi Zhang, Takayuki Nonoyama, Tasuku Nakajima, Takayuki Kurokawa, Yasuaki Takagid, Jian Ping Gong
    JOURNAL OF MATERIALS CHEMISTRY B 3 (39) 7658 - 7666 2050-750X 2015 [Refereed][Not invited]
     
    Marine collagen has been attracting attention as a medical material in recent times due to the low risk of pathogen infection compared to animal collagen. Type I collagen extracted from the swim bladder of Bester sturgeon fish has excellent characteristics such as high denaturation temperature, high solubility, low viscosity and an extremely fast rate to form large bundle of fibers under certain conditions. These specific characteristics of swim bladder collagen (SBC) permit us to create stable, disk shaped hydrogels with concentric orientation of collagen fibers by the controlled diffusion of neutral buffer through collagen solution at room temperature. However, traditionally used animal collagens, e.g. calf skin collagen (CSC) and porcine skin collagen (PSC), could not form any stable and oriented structure by this method. The mechanism of the superstructure formation of SBC by a diffusion induced gelation process has been explored. The fast fibrillogenesis rate of SBC causes a quick squeezing out of the solvent from the gel phase to the sol phase during gelation, which builds an internal stress at the gel-sol interface. The tensile stress induces the collagen molecules of the gel phase to align along the gel-sol interface direction to give this concentric ring-shaped orientation pattern. On the other hand, the slow fibrillogenesis rate of animal collagens due to the high viscosity of the solution does not favor the ordered structure formation. The denaturation temperature of SBC increases significantly from 31 degrees C to 43 degrees C after gelation, whereas that of CSC and PSC were found to increase a little. Rheology experiment shows that the SBC gel has storage modulus larger than 15 kPa. The SBC hydrogels with thermal and mechanical stability have potential as bio-materials for tissue engineering applications.
  • Tasuku Nakajima, Corentin Durand, Xu Feng Li, Md. Anamul Haque, Takayuki Kurokawa, Jian Ping Gong
    SOFT MATTER 11 (2) 237 - 240 1744-683X 2015 [Refereed][Not invited]
     
    PDGI-PAAm gels with well oriented lipid bilayers show a quasi-unidirectional shrinkage upon uniaxial stretching along the bilayers. They shrink largely parallel to the bilayer but slightly perpendicular to it in order not to increase the bilayer area and its interfacial energy. Such an anisotropic deformation can be well-modelled based on classical theories for gel networks and lipid layers.
  • Songmiao Liang, Jian Hu, Zi Liang Wu, Takayuki Kurokawa, Jian Ping Gong
    Extreme Mechanics Letters 1 17 - 22 2352-4316 2014/12/01 [Refereed][Not invited]
     
    Solvent-triggered isometric stress generation of an ultrathin and tough triple-network (TN) hydrogel was systematically studied as functions of the pre-strain and ethanol/water mixture solvent. The obtained results along with the solvent-induced changes in the volume and modulus of the hydrogel were further analyzed with emphasis on clarifying the stress generation mechanism of the TN gel. Ca2+-triggered stress generation of the gel was also preliminarily explored. High stress generation of 0.4 MPa was obtained within tens of seconds at the low pre-strain of 25% by alternating water and ethanol. Both negative and positive stress generation of the gel were achieved just by changing the composition of the ethanol/water mixture solvent. Mechanism analysis indicates that, modulus change of the gel is the dominant reason for their solvent-triggered high and fast stress generation. In the case of the Ca2+-triggered stress generation of the gel, it is also attributed to the modulus change induced by the physical cross-linking of Ca2+ between the negatively charged first network chains of the TN hydrogel.
  • Zi Liang Wu, Riku Takahashi, Daisuke Sawada, Md. Arifuzzaman, Tasuku Nakajima, Takayuki Kurokawa, Jian Hu, Jian Ping Gong
    MACROMOLECULES 47 (20) 7208 - 7214 0024-9297 2014/10 [Refereed][Not invited]
     
    Diffusion of multivalent metallic ions into aqueous solution of rigid, negatively charged macromolecules of high concentration is an effective approach to prepare macroscopically anisotropic hydrogels. However, the mechanism for superstructure formation is still not clear. By observing the mixing process of a small drop of CaCl2 solution with solution of a rigid polyanion, poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT), under the polarizing optical microscope, the diffusion profile of Ca2+ and detailed anisotropic gelation process of PBDT are revealed. Diffusion of Ca2+ into the surrounding PBDT solution immediately induces the formation of physical liquid crystalline (LC) gel with concentric alignment of PBDT. The thickness d of this region increases with diffusion time t, obeying the diffusion law d similar to t1/2. A thin ring of constant width (similar to 100 mu m) with radial alignment of PBDT appears at the diffusion/reaction front, ahead of the concentric alignment region. When two drops of CaCl2 fluxes meet, their outside thin rings interact with each other and the PBDT in this contacting region orients +/- 45 degrees to the midline of the two drops. From these observations, we rationally contend that the internal stress induced by the contraction of gel phase is responsible for the ion diffusion-induced PBDT orientations. This structure formation mechanism gives insight into other diffusion-directed anisotropic gelation systems.
  • Eijiro Maeda, Takehiro Tsutsumi, Nobuto Kitamura, Takayuki Kurokawa, Jian Ping Gong, Kazunori Yasuda, Toshiro Ohashi
    JOURNAL OF BIOMECHANICS 47 (13) 3408 - 3414 0021-9290 2014/10 [Refereed][Not invited]
     
    A double-network (DN) gel, which was composed of poly(2-acrylamido-2-methylpropanesulfonic acid) and poly(N,N'-dimethyl acrylamide) (PAMPS/PDMAAm), has the potential to induce chondrogenesis both in vitro and in vivo. The present study investigated the biomechanical and biological responses of chondrogenic progenitor ATDC5 cells cultured on the DN gel. ATDC5 cells were cultured on a polystyrene surface without insulin (Culture 1) and with insulin (Culture 2), and on the DN gel without insulin (Culture 3). The cultured cells were evaluated using micropipette aspiration for cell Young's modulus and qPCR for gene expression of chondrogenic and actin organization markers on days 3, 7 and 14. On day 3, the cells in Culture 3 formed nodules, in which the cells exhibited an actin cortical layer inside them, and gene expression of type-II collagen, aggrecan, and SOX9 was significantly higher in Culture 3 than Cultures 1 and 2 (p < 0.05). Young's modulus in Culture 3 was significantly higher than that in Culture 1 throughout the testing period (p < 0.05) and that in Culture 2 on day 14 (p < 0.01). There was continuous expression of actin organization markers in Culture 3. This study highlights that the cells on the DN gel increased the modulus and mRNA expression of chondrogenic markers at an earlier time point with a greater magnitude compared to those on the polystyrene surface with insulin. This study also demonstrates a possible strong interrelation among alteration of cell mechanical properties, changes in actin organization and the induction of chondrogenic differentiation. (C) 2014 Elsevier Ltd. All rights reserved.
  • Yusuke Inagaki, Nobuto Kitamura, Takayuki Kurokawa, Yasuhito Tanaka, Jian P. Gong, Kazunori Yasuda, Harukazu Tohyama
    BMC MUSCULOSKELETAL DISORDERS 15 320  1471-2474 2014/09 [Refereed][Not invited]
     
    Background: Recently, several animal studies have found that spontaneous hyaline cartilage regeneration can be induced in vivo within a large osteochondral defect by implanting a synthetic double-network (DN) hydrogel, which is composed of poly-(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and poly-(N,N'-dimethyl acrylamide) (PDMAAm), at the bottom of the defect. However, the effect of hydrogel on hyaline cartilage regeneration remains unexplained. The purpose of this study was to investigate the chondrogenic differentiation of C3H10T1/2 cells on PAMPS/PDMAAm DN gel. Methods: C3H10T1/2 cells of 1.0 x 10(5) were cultured on PAMPS/PDMAAm DN gel in polystyrene tissue culture dishes or directly on polystyrene tissue culture dishes. We compared cultured cells on PAMPS/PDMAAm DN gel with those on polystyrene dishes by morphology using phase-contrast microscopy, mRNA expression of aggrecan, type I collagen, type II collagen, Sox 9 and osteocalcin using real-time RT-PCR, and local expression of type II collagen using immunocytochemistry. Results: C3H10T1/2 cells cultured on the PAMPS/PDMAAm DN gels formed focal adhesions, aggregated rapidly and developed into large nodules within 7 days, while the cells cultured on the polystyrene surface did not. The mRNA levels of aggrecan, type I collagen, type II collagen, Sox 9 and osteocalcin were significantly greater in cells cultured on the PAMPS/PDMAAm DN gel than in those cultured on polystyrene dishes. In addition, C3H10T1/2 cells cultured on PAMPS/PDMAAm DN gel expressed more type II collagen at the protein level when compared with cells cultured on polystyrene dishes. Conclusions: The present study showed that PAMPS/PDMAAm DN gel enhanced chondrogenesis of C3H10T1/2 cells, which are functionally similar to mesenchymal stem cells. This suggests that mesenchymal stem cells from the bone marrow contribute to spontaneous hyaline cartilage regeneration in vivo in large osteochondral defects after implantation of PAMPS/PDMAAm DN gels.
  • Feng Luo, Tao Lin Sun, Tasuku Nakajima, Takayuki Kurokawa, Yu Zhao, Abu Bin Ihsan, Hong Lei Guo, Xu Feng Li, Jian Ping Gong
    MACROMOLECULES 47 (17) 6037 - 6046 0024-9297 2014/09 [Refereed][Not invited]
     
    Recently, we have reported that polyampholytes, synthesized from free radical copolymerization of anionic monomer and cationic monomer, form physical hydrogels of high toughness and self-healing. The random distribution of the opposite charges forms ionic bonds of a wide distribution of strength. The strong bonds serve as permanent cross-links, imparting elasticity, whereas the weak bonds serves as reversible sacrificial bonds by breaking and reforming to dissipate energy. In this work, we focus on the rupture behaviors of the polyampholyte physical hydrogel, P(NaSS-co-MPTC), copolymerized from sodium p-styrenesulfonate (NaSS) and 3-(methacryloylamino)propyltrimethylammonium chloride (MPTC). Tensile test and pure shear test were performed at various stretch rates in the viscoelastic responses region of the material. Tensile test showed yielding, strain softening, and strain hardening, revealing the dually cross-linked feature of the gel. Pure shear test showed crack blunting at the notched tip and a large yielding zone with butterfly shaped birefringence pattern ahead of the crack tip. After blunting, crack advanced at steady-state velocity with a constant angle. The conditions for the occurrence of crack blunting and variables governing the crack advancing angle are discussed. We found that even for these highly stretchable samples, significant blunting only occurs when the tensile fracture stress sigma(f) is larger than modulus E by a factor of about 2, in consistent with Huis theoretical prediction for elastic materials. The crack advancing angle theta was found to be proportional to sigma(y)/E over a wide stretch rate range, where sigma(y) is the yielding stress. In addition, the fracture energy was correlated to small strain modulus by a power law in the viscoelastic response region. This systematic study will merit revealing the fracture mechanism of tough viscoelastic materials including biological tissues and recently developed tough and highly stretchable hydrogels.
  • Youfeng Yue, Takayuki Kurokawa, Md Anamul Haque, Tasuku Nakajima, Takayuki Nonoyama, Xufeng Li, Itsuro Kajiwara, Jian Ping Gong
    NATURE COMMUNICATIONS 5 4659  2041-1723 2014/08 [Refereed][Not invited]
     
    Photonic crystals with tunability in the visible region are of great interest for controlling light diffraction. Mechanochromic photonic materials are periodically structured soft materials designed with a photonic stop-band that can be tuned by mechanical forces to reflect specific colours. Soft photonic materials with broad colour tunability and fast colour switching are invaluable for application. Here we report a novel mechano-actuated, soft photonic hydrogel that has an ultrafast-response time, full-colour tunable range, high spatial resolution and can be actuated by a very small compressive stress. In addition, the material has excellent mechanical stability and the colour can be reversibly switched at high frequency more than 10,000 times without degradation. This material can be used in optical devices, such as full-colour display and sensors to visualize the time evolution of complicated stress/strain fields, for example, generated during the motion of biological cells.
  • Riku Takahashi, Zi Liang Wu, Md Arifuzzaman, Takayuki Nonoyama, Tasuku Nakajima, Takayuki Kurokawa, Jian Ping Gong
    NATURE COMMUNICATIONS 5 4490  2041-1723 2014/08 [Refereed][Not invited]
     
    Biomacromolecules usually form complex superstructures in natural biotissues, such as different alignments of collagen fibres in articular cartilages, for multifunctionalities. Inspired by nature, there are efforts towards developing multiscale ordered structures in hydrogels (recognized as one of the best candidates of soft biotissues). However, creating complex superstructures in gels are hardly realized because of the absence of effective approaches to control the localized molecular orientation. Here we introduce a method to create various superstructures of rigid polyanions in polycationic hydrogels. The control of localized orientation of rigid molecules, which are sensitive to the internal stress field of the gel, is achieved by tuning the swelling mismatch between masked and unmasked regions of the photolithographic patterned gel. Furthermore, we develop a double network structure to toughen the hydrogels with programmed superstructures, which deform reversibly under large strain. This work presents a promising pathway to develop superstructures in hydrogels and should shed light on designing biomimetic materials with intricate molecular alignments.
  • Daisuke Inoue, Arif Md. Rashedul Kabir, Kazuki Sada, Jian Ping Gong, Akira Kakugo
    Soft Actuators: Materials, Modeling, Applications, and Future Perspectives 9784431547679 475 - 487 2014/07/01 [Refereed][Not invited]
     
    Biomolecular motor systems microtubule/kinesin, actin/myosin are constituent components of biological power unit, which can perform mechanical work by converting chemical energy obtained from hydrolysis of adenosine triphosphate (ATP). The biomolecular motors are organized into highly complex and ordered structures as observed in muscle, stress fiber, contractile ring which exhibit various functions. Performance of these natural machines are much attractive compared to man-made machine. Therefore, to utilize the advantage of these natural machines biological motors have been proposed as the building blocks of ATP-driven bio-machine. In this chapter, different methodologies for designing biomolecular motor based bio-machines through non-equilibrium self-organization process are described.
  • Nobuto Kitamura, Takayuki Kurokawa, Takaaki Fukui, Jian P. Gong, Kazunori Yasuda
    BMC MUSCULOSKELETAL DISORDERS 15 222  1471-2474 2014/07 [Refereed][Not invited]
     
    Background: A double-network (DN) gel, which was composed of poly-(2-Acrylamido-2-methylpropanesulfonic acid) and poly-(N,N'-dimethyl acrylamide) (PAMPS/PDMAAm), has the potential to induce chondrogenesis both in vitro and in vivo. The present study investigated whether DN gel induced chondrogenic differentiation of ATDC5 cells in a maintenance medium without insulin, and whether supplementation of hyaluronic acid enhanced the chondrogenic differentiation effect of DN gel. Methods: ATDC5 cells were cultured on the DN gel and the polystyrene (PS) dish in maintenance media without insulin for 21 days. Hyaluronic acid having a molecular weight of approximately 800 kDa was supplemented into the medium so that the concentration became 0.01, 0.1, or 1.0 mg/mL. The cultured cells were evaluated using immunocytochemistry for type-2 collagen and real time PCR for gene expression of type-2 collagen, aggrecan, and Sox9 at 7 and 21 days of culture. Results: The cells cultured on the DN gel formed nodules and were stained with an anti-type-2 collagen antibody, and expression of type-2 collagen and aggrecan mRNA was significantly greater on the DN gel than on the PS dish surface (p < 0.05) in the hyaluronic acid-free maintenance medium. Hyaluronic acid supplementation of a high concentration (1.0 mg/mL) significantly enhanced expression of type-2 collagen and aggrecan mRNA in comparison with culture without hyaluronic acid at 21 days (p < 0.05). Conclusions: The DN gel induced chondrogenic differentiation of ATDC5 cells without insulin. This effect was significantly affected by hyaluronic acid, depending on the level of concentration. There is a high possibility that hyaluronic acid plays an important role in the in vivo hyaline cartilage regeneration phenomenon induced by the DN gel.
  • Jian Hu, Takayuki Kurokawa, Tasuku Nakajima, Zi Liang Wu, Song Miao Liang, Jian Ping Gong
    MACROMOLECULES 47 (11) 3587 - 3594 0024-9297 2014/06 [Refereed][Not invited]
     
    We have found that lightly cross-linked neutral hydrogels containing microgels of densely cross-linked polyelectrolyte show high strength and toughness. These kinds of hydrogels, named as microgel-reinforced (MR) hydrogels, are a two-phase composite, where the disperse phase is the microgel with the double network (DN) structure and the continuous phase is the soft neutral gel matrix. The brittle polyelectrolyte network of the DN microgels, though in disperse phase, also serves as sacrificial bonds to toughen the material, similar to conventional DN gels. In this paper, we study the internal fracture process of the MR gel under uniaxial tension. The tensile stress-strain curve of the MR gel is charaterized by four regions according to its differential curve: elastic region (0 < epsilon < 1), preyielding region (1 < epsilon < 3), yielding region (3 < epsilon < 7), and strain hardening region (epsilon > 7). The morphology change of microgels in the reswollen MR gels after prestretching tells that the internal fracture of microgels, which occurs beyond the elastic region (epsilon > 1), is anisotropic. That is, the short chains in the tensile direction fracture first (1 < epsilon < 3); at large stretching, both the long chains in the tensile direction and the short chains in the transverse direction fracture (3 < epsilon < 7), followed by the fracture of the long chains in the transverse direction (epsilon > 7). These anisotropic fracture behaviors are in similar to bulk DN gels. Moreover, at each stage of the tensile process, large microgels always fracture prior to small ones and own higher fracture efficiency in the chain rupture than the smaller ones. This size effect is attributed to the stress concentration effect around the two poles of large microgels induced by the close distance from their neighboring microgels.
  • Jamil Ahmed, Honglei Guo, Tetsurou Yamamoto, Takayuki Kurokawa, Masakazu Takahata, Tasuku Nakajima, Jian Ping Gong
    MACROMOLECULES 47 (9) 3101 - 3107 0024-9297 2014/05 [Refereed][Not invited]
     
    Polyzwitterionic materials, which have both cationic and anionic groups in each repeating unit of polymer, show excellent antibiofouling properties. In this study, the surface friction of carboxybetaine type zwitterionic hydrogels, poly(N-(carboxymethyl)-N,N-dimethy1-2-(methacryloyloxy)-ethanaminium, inner salt) (PCDME), against glass substrates were investigated in aqueous solutions. The friction measurement was performed using a rheometer with parallel plate geometry and the sliding interface was monitored during the measurement. The frictional stress on glass was high in water and it showed weak dependence on pressure as long as the two sliding surfaces were in complete contact. The results performed in solutions with varied ionic strength revealed that the high friction on glass substrates has an electrostatic origin. The electrostatic potential measurement revealed that the PCDME gels have an isoelectric point at pH 8.5. Since the glass substrates carrying negative charges in pure water, the gel and the glass have electrostatic attraction in water. Study on the effect of pH has shown that below pH 8.5, attraction between the positively charged gels and negatively charged glass gives high friction, while above pH 8.5, the electrical double layer repulsion between two negatively charged surfaces gives low friction. From these results, it is concluded that although the PCDME gels behave like neutral gels in the bulk properties, their surface properties sensitively change with pH and ionic strength of the medium.
  • Jian Ping Gong
    SCIENCE 344 (6180) 161 - 162 0036-8075 2014/04 [Not refereed][Invited]
  • Takaaki Fukui, Nobuto Kitamura, Takayuki Kurokawa, Masashi Yokota, Eiji Kondo, Jian Ping Gong, Kazunori Yasuda
    JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE 25 (4) 1173 - 1182 0957-4530 2014/04 [Refereed][Not invited]
     
    Implantation of PAMPS/PDMAAm double-network (DN) gel can induce hyaline cartilage regeneration in the osteochondral defect. However, it is a problem that the volume of the regenerated cartilage tissue is gradually reduced at 12 weeks. This study investigated whether intra-articular administration of hyaluronic acid (HA) increases the volume of the cartilage regenerated with the DN gel at 12 weeks. A total of 48 rabbits were used in this study. A cylindrical osteochondral defect created in the bilateral femoral trochlea was treated with DN gel (Group DN) or left without any implantation (Group C). In both Groups, we injected 1.0 mL of HA in the left knee, and 1.0 mL of saline solution in the right knee. Quantitative histological evaluations were performed at 2, 4, and 12 weeks, and PCR analysis was performed at 2 and 4 weeks after surgery. In Group DN, the proteoglycan-rich area was significantly greater in the HA-injected knees than in the saline-injected knees at 12 weeks (P = 0.0247), and expression of type 2 collagen, aggrecan, and Sox9 mRNAs was significantly greater in the HA-injected knees than in the saline-injected knees at 2 weeks (P = 0.0475, P = 0.0257, P = 0.0222, respectively). The intra-articular administration of HA significantly enhanced these gene expression at 2 weeks and significantly increased the volume of the hyaline cartilage regenerated by implantation of a DN gel at 12 weeks. This information is important to develop an additional method to increase the volume of the hyaline cartilage tissue in a potential cartilage regeneration strategy using the DN gel.
  • 一軸配向二分子膜によるハイドロゲルの高靱性化
    中島 祐, グン剣萍
    超分子研究会アニュアルレビュー 34 14 - 15 2014/03 [Not refereed][Invited]
  • Hyuck Joon Kwon, Kazunori Yasuda, Jian Ping Gong, Yoshihiro Ohmiya
    MACROMOLECULAR RESEARCH 22 (3) 227 - 235 1598-5032 2014/03 [Refereed][Invited]
     
    Polyelectrolyte gels are charged polymer networks with macro-ions fixed on the polymer chains. These gels have considerable potential for biological applications such as cellular scaffolds and the replacement of various biological tissues. Moreover, high strength up to several tens of megapascals can be obtained with polyelectrolyte gels by incorporating double network structure in the gel. This article gives a concise review to introduce the fundamental properties of polyelectrolyte gels and biological applications for tissue engineering using their characteristic properties. Applications of polyelectrolyte gels have been highlighted in the fields of artificial muscle, artificial corneas, artificial cartilage, scaffolds for in vitro stem cell culture, and scaffolds for in vivo cartilage regeneration. This review suggests that polyelectrolyte gels would be a useful material for the successful replacement and regeneration of damaged or diseased tissues.
  • Nafees Ahmed, Takayuki Murosaki, Takayuki Kurokawa, Akira Kakugo, Shintaro Yashima, Yasuyuki Nogata, Jian Ping Gong
    BIOFOULING 30 (3) 271 - 279 0892-7014 2014/03 [Refereed][Not invited]
     
    A long-term investigation of the shell shape and the basal morphology of barnacles grown on tough, double-network (DN) hydrogels and polydimethylsiloxane (PDMS) elastomer was conducted in a laboratory environment. The elastic modulus of these soft substrata varied between 0.01 and 0.47MPa. Polystyrene (PS) (elastic modulus, 3 GPa) was used as a hard substratum control. It was found that the shell shape and the basal plate morphology of barnacles were different on the rigid PS substratum compared to the soft substrata of PDMS and DN hydrogels. Barnacles on the PS substratum had a truncated cone shape with a flat basal plate while on soft PDMS and DN gels, barnacles had a pseudo-cylindrical shape and their basal plates showed curvature. In addition, a large adhesive layer was observed under barnacles on PDMS, but not on DN gels. The effect of substratum stiffness is discussed in terms of barnacle muscle contraction, whereby the relative stiffness of the substratum compared to that of the muscle is considered as the key parameter.
  • Saika Ahmed, Tasuku Nakajima, Takayuki Kurokawa, Md Anamul Haque, Jian Ping Gong
    POLYMER 55 (3) 914 - 923 0032-3861 2014/02 [Refereed][Not invited]
     
    Tough double network (DN) hydrogels are a kind of interpenetrating network (IPN) gels with a contrasting structure; they consist of a rigid and brittle 1st network with dilute, densely cross-linked short chains and a soft and ductile 2nd network with concentrated, loosely cross-linked long chains. In this work, we focus on how the brittle gel changes into a tough one by increasing the amount of ductile component. By comparing the molecular structures of the individual first network and second network gels, we found that the true key mechanical factor that governs the brittle ductile transition is the fracture stress ratio of the two networks, sigma(f,2)/sigma(f,1). This ratio is related to the density ratio of elastically effective polymer strands of the two networks, nu(e,2)/nu(e,1), where the inter-network topological entanglement makes dominant contribution to nu(e,2). When nu(e,2)/nu(e,1) < k = 3.8-9.5, the second network fractures right after the fracture of the first network, and the gels are brittle. When nu(e,2)/nu(e,1) > k, only the first network fractures. As a result, the brittle first network serves as sacrificial bonds, imparting toughness of DN gels. The study also confirms that the load transfer between the two networks is via inter-network topological entanglement. This result provides essential information to design tough materials based on the double network concept. (C) 2014 Elsevier Ltd. All rights reserved.
  • Tetsurou Yamamoto, Takayuki Kurokawa, Jamil Ahmed, Gen Kamita, Shintaro Yashima, Yuichiro Furukawa, Yuko Ota, Hidemitsu Furukawa, Jian Ping Gong
    SOFT MATTER 10 (30) 5589 - 5596 1744-683X 2014 [Refereed][Not invited]
     
    Direct observation of hydrogel contact with a solid surface in water is indispensable for understanding the friction, lubrication, and adhesion of hydrogels under water. However, this is a difficult task since the refractive index of hydrogels is very close to that of water. In this paper, we present a novel method to in situ observe the macroscopic contact of hydrogels with a solid surface based on the principle of critical refraction. This method was applied to investigate the sliding friction of a polyacrylamide (PAAm) hydrogel with glass by using a strain-controlled parallel-plate rheometer. The study revealed that when the compressive pressure is not very high, the hydrogel forms a heterogeneous contact with the glass, and a macro-scale water drop is trapped at the soft interface. The pre-trapped water spreads over the interface to decrease the contact area with the increase in sliding velocity, which dramatically reduces the friction of the hydrogel. The study also revealed that this heterogeneous contact is the reason for the poor reproducibility of hydrogel friction that has been often observed in previous studies. Under the condition of homogeneous full contact, the molecular origin of hydrogel friction in water is discussed. This study highlights the importance of direct interfacial observation to reveal the friction mechanism of hydrogels.
  • Shintaro Yashima, Natsuko Takase, Takayuki Kurokawa, Jian Ping Gong
    SOFT MATTER 10 (18) 3192 - 3199 1744-683X 2014 [Refereed][Not invited]
     
    This study investigated the effect of hydrogel surface roughness on its sliding friction against a solid substrate having modestly adhesive interaction with hydrogels under small normal pressure in water. The friction test was performed between bulk polyacrylamide hydrogels of varied surface roughness and a smooth glass substrate by using a strain-controlled rheometer with parallel-plates geometry. At small pressure (normal strain 1.4-3.6%), the flat surface gel showed a poor reproducibility in friction. In contrast, the gels with a surface roughness of 1-10 mm order showed well reproducible friction behaviors and their frictional stress was larger than that of the flat surface hydrogel. Furthermore, the flat gel showed an elasto-hydrodynamic transition while the rough gels showed a monotonous decrease of friction with velocity. The difference between the flat surface and the rough surface diminished with the increase of the normal pressure. These phenomena are associated with the different contact behaviors of these soft hydrogels in liquid, as revealed by the observation of the interface using a confocal laser microscope.
  • Yu Zhao, Tasuku Nakajima, Jing Jing Yang, Takayuki Kurokawa, Jian Liu, Jishun Lu, Shuji Mizumoto, Kazuyuki Sugahara, Nobuto Kitamura, Kazunori Yasuda, A. U. D. Daniels, Jian Ping Gong
    ADVANCED MATERIALS 26 (3) 436 - 442 0935-9648 2014/01 [Refereed][Not invited]
  • Md. Arifuzzaman, Zi Liang Wu, Riku Takahashi, Takayuki Kurokawa, Tasuku Nakajima, Jian Ping Gong
    Macromolecules 46 (22) 9083 - 9090 0024-9297 2013/11/26 [Refereed][Not invited]
     
    In this paper, we developed several kinds of ordered structures in hydrogels with different geometries and sizes by harnessing heterogeneous swelling induced mechanical instability, i.e., surface creasing, which leads to molecular orientations along the tensile direction. These hydrogels were synthesized by polymerization of a cationic monomer, N-[3-(N,N-dimethylamino) propyl] acrylamide methyl chloride quaternary (DMAPAA-Q) and a chemical cross-linker, in the presence of a small amount of the semirigid polyanion, poly(2,2′-disulfonyl-4,4′-benzidine terephthalamide) (PBDT), as dopant. During the swelling process of as-prepared gels, surface creasing occurs and induces formation of a lattice-like periodic ordered structure, which is maintained in the swollen gels due to the formation of strong polyion complex. Besides this structure formed at the central part of gel sheets, PBDTs align parallel to the gel boundary at the edge of gels with a cuboid, disk, or ring shape. The size of the two regions with different structures and the size of each unit of lattice-like pattern are related to the geometry and size of the gels. The formation of different ordered structures was found due to the different mechanical instabilities at different parts of the gel during the heterogeneous swelling. This work presenting the creation of ordered structures in hydrogels by tuning the mechanical instability will pave the way to develop other functional structured materials and merit revealing the formation mechanism of ordered structures in soft biotissues during the nonequilibrium growth. © 2013 American Chemical Society.
  • Yuki Akagi, Hayato Sakurai, Jian Ping Gong, Ung-il Chung, Takamasa Sakai
    JOURNAL OF CHEMICAL PHYSICS 139 (14) 144905-1 - 144905-6 0021-9606 2013/10 [Refereed][Not invited]
     
    We have investigated the fracture behaviors of tetra-arm polyethylene glycol (Tetra-PEG) gels with controlled network structures. Tetra-PEG gels were prepared by AB-type crosslink-coupling of mutually reactive tetra-arm prepolymers with different concentrations and molecular weights. This series of controlled network structures, for the first time, enabled us to quantitatively examine the Lake-Thomas model, which is the most popular model predicting fracture energies of elastomers. The experimental data showed good agreement with the Lake-Thomas model, and indicated a new molecular interpretation for the displacement length (L), the area around a crack tip within which the network strands are fully stretched. L corresponded to the three times of end-to-end distance of network strands, regardless of all parameters examined. We conclude that the Lake-Thomas model can quantitatively predict the fracture energy of polymer network without trapped entanglements, with the enhancement factor being near 3. (C) 2013 AIP Publishing LLC.
  • Tao Lin Sun, Takayuki Kurokawa, Shinya Kuroda, Abu Bin Ihsan, Taigo Akasaki, Koshiro Sato, Md Anamul Haque, Tasuku Nakajima, Jian Ping Gong
    NATURE MATERIALS 12 (10) 932 - 937 1476-1122 2013/10 [Refereed][Not invited]
     
    Hydrogels attract great attention as biomaterials as a result of their soft and wet nature, similar to that of biological tissues. Recent inventions of several tough hydrogels show their potential as structural biomaterials, such as cartilage. Any given application, however, requires a combination of mechanical properties including stiffness, strength, toughness, damping, fatigue resistance and self-healing, along with biocompatibility. This combination is rarely realized. Here, we report that polyampholytes, polymers bearing randomly dispersed cationic and anionic repeat groups, form tough and viscoelastic hydrogels with multiple mechanical properties. The randomness makes ionic bonds of a wide distribution of strength. The strong bonds serve as permanent crosslinks, imparting elasticity, whereas the weak bonds reversibly break and re-form, dissipating energy. These physical hydrogels of supramolecular structure can be tuned to change multiple mechanical properties over wide ranges by using diverse ionic combinations. This polyampholyte approach is synthetically simple and dramatically increases the choice of tough hydrogels for applications.
  • Koshiro Sato, Md. Anamul Haque, Gen Kamita, You Feng Yue, Takayuki Kurokawa, Jian Ping Gong
    Journal of the Japan Society of Colour Material 86 (8) 290 - 294 2013/08 [Refereed][Invited]
  • Tiffany C. Suekama, Jian Hu, Takayuki Kurokawa, Jian Ping Gong, Stevin H. Gehrke
    MACROMOLECULAR SYMPOSIA 329 (1) 9 - 18 1022-1360 2013/07 [Refereed][Invited]
     
    High strength double-network (DN) biopolymer-based hydrogels were created using copolymers of methacrylated chondroitin sulfate (MCS) and poly (ethylene glycol) diacrylate (PEGDA) as the first network and polyacrylamide (PAAm) as the second network. The concentration and cross-linking of the networks were adjusted to control the mechanical properties including the failure stress, failure strain, Young's modulus, and yielding behavior. First, we increased the cross-linking of the first network both by increasing the MCS concentration from 13 to 20 wt% and by copolymerizing MCS with 2 to 6 wt% PEGDA. The additional cross-linking increased the Young's modulus as much as five times, reaching 3.3 MPa, and the failure stress up as much as four times, reaching 2.9 MPa. However, this also reduced failure strain from a high of 2.9 mm/mm to a low of 0.12 mm/mm and diminished the yielding region. Changes in the concentrations of acrylamide or its cross-linking with N,N'-methylenebisacrylamide (BIS) in the second network had a lesser effect on the DN properties. We hypothesized that to obtain a yielding region which results in high toughness, we need to alter the cross-linking of the first network such that the yield stress of the MCS-PEGDA/PAAm DN does not exceed the failure stress of PAAm network. Because of the wide range of mechanical properties achieved in these DNs with limited changes in the swelling degrees, unlike conventional single-network gels, the DN approach allows attainment of a much greater range of mechanical behavior than is possible with single networks.
  • Takayuki Kurokawa, Md. Anamul Haque, Jian Ping Gong
    Kobunshi Ronbunshu 70 (7) 309 - 316 0386-2186 2013/07 [Refereed][Invited]
     
    In this highlight, we introduce a novel anisotropic hydrogel with a perfect ID photonic crystal structure based on the uni-axial alignment of lamellar bilayers. The polymerized lamellar bilayers were stacked periodically and entrapped in a Polyacrylamide matrix. This hydrogel shows perfect one-dimensional swelling and magnificent structural color by multilayer interference according to Bragg's law of diffraction. Owing to the softness and large deformability, the color of the gel can reversibly be tuned by compressive mechanical stimulation over the entire visible wavelength range. The single-domain lamellar bilayers not only diffract light, but also serve as reversible sacrificial 'bonds' that dissociate upon deformation, exhibiting large hysteresis as an energy dissipation mechanism. This gives the gel high tensile strength and fatigue resistance. Both the molecular dissociation and lipid-like mobile nature of DGI molecules in the bilayers dramatically enhance the resistance against crack propagation by showing an extra-ordinary blunting effect, which gives the gel very high toughness. ©2013, The Society of Polymer Science,.
  • Md. Anamul Haque, Jian Ping Gong
    REACTIVE & FUNCTIONAL POLYMERS 73 (7) 929 - 935 1381-5148 2013/07 [Refereed][Invited]
     
    A novel hybrid hydrogel has been developed by combining bilayer-based lamellar structure of a self-assembled polymer surfactant and polymer network of conventional hydrogel system. A wide range of lamellar structure from micro-domain up to macro-domain (cm-scale) has been successfully generated in the hydrogel. Flat, infinitely large, and perfectly aligned lamellar macro-domain was formed by applying mechanical shear to the gel forming precursor solution containing monomer, cross-linker, and initiator. The obtained hydrogel system contains macroscopic, single-domain, periodical stacking of integrated microscopic lamellar bilayers inside the polymer matrix of the hydrogel. Periodical stacking of the bilayers in the hydrogel selectively diffract visible light to exhibit magnificent structural color. Due to the uniaxial orientation of the bilayer, the hydrogel possesses superb functions that have never been realized before, such as the one-dimensional swelling, anisotropic Young's modulus, anisotropic molecular permeation, and diffusion. Furthermore, the hydrogel exhibits excellent color tuning ability over a wide spectrum range by mechanical stimuli. (c) 2013 Elsevier Ltd. All rights reserved.
  • You Feng Yue, M. Anamul Haque, Takayuki Kurokawa, Tasuku Nakajima, Jian Ping Gong
    Advanced Materials 25 (22) 3106 - 3110 0935-9648 2013/06/11 [Refereed][Not invited]
     
    A lamellar hydrogel with high toughness, exhibiting ternary stimuli-responsive structural color changes has been synthesized. The gel consists of alternating hard layers of a polymeric surfactant (PDGI) and soft layers of interpenetrating networks of poly(acrylamide)-poly(acrylic acid). Reversible, wide range switching of the stop-band position was achieved using different external stimuli of temperature, pH, and stress/strain. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Tasuku Nakajima, Yuki Fukuda, Takayuld Kurokawa, Takamasa Sakai, Ung-il Chung, Jian Ping Gong
    ACS MACRO LETTERS 2 (6) 518 - 521 2161-1653 2013/06 [Refereed][Not invited]
     
    To investigate the effect of inhomogeneity in the first network on the enormously high toughness of double network (DN) gels, we fabricated DN gels with a nearly homogeneous first network structure (named St-TPEG/PAAm DN gels) based on tetra-PEG (TPEG) gels via a molecular stent method. The St-TPEG/PAAm DN gels also show excellent mechanical properties and yielding-like phenomena comparable to conventional DN gels. This result demonstrates that the inhomogeneity within the first network is not essential for the specific toughening mechanism of DN gels. On the other hand, the St-TPEG/PAAm DN gels and conventional DN gels undergo substantially different fracture processes before the yielding point. This suggests the importance of a "homogenization process" for the yielding of DN gels. Since the St-TPEG/PAAm DN gels consist of a well-defined first network, they may serve as model DN gels in the future for further studies on fracture processes of DN gels.
  • Zi Liang Wu, Md. Arifuzzaman, Takayuki Kurokawa, Khoa Le, Jian Hu, Tao Lin Sun, Hidemitsu Furukawa, Hiroyasu Masunaga, Jian Ping Gong
    MACROMOLECULES 46 (9) 3581 - 3586 0024-9297 2013/05 [Refereed][Not invited]
     
    In this article, we report the supramolecular assemblies of a semirigid polyelectrolyte, poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) in water. Cryo-TEM observation and SAXS measurement reveal that PBDT forms bundle-like structure even in very dilute concentration, C-p, of 0.02 wt %. These bundle-like assemblies serve as new primary building blocks and self-assemble further as C-p increases, to form large associations with or without long-range orientation. When 2 wt % < C-p < 6 wt %, liquid liquid phase separation occurs. Some of the supramolecular associations form bipolar liquid crystalline (LC) droplets via a typical nucleation and growth process. The droplets grow up by the coalescence of small ones and sediment under the gravity and coalesce to form a bottom nematic phase. When C-p 6 wt %, the solutions are in a uniform nematic phase. The existence of these preliminary supramolecular assemblies of PBDT in aqueous solutions should be crucial for the formation of nematic LC phase at a significantly low C-p, as well as the formation of macroscopic ordered structures in hydrogels via electrostatic interaction between PBDT and oppositely charge multivalent metallic ion or polycation.
  • S. Ronken, D. Wirz, A. U. Daniels, T. Kurokawa, J. P. Gong, M. P. Arnold
    BIOMECHANICS AND MODELING IN MECHANOBIOLOGY 12 (2) 243 - 248 1617-7959 2013/04 [Refereed][Not invited]
     
    Since articular cartilage has a limited potential for spontaneous healing, various techniques are employed to repair cartilage lesions. Acrylate-based double-network (DN) hydrogels containing similar to 90% water have shown promising properties as repair materials for skeletal system soft tissues. Although their mechanical properties approach those of native cartilage, the critical factor-stiffness-of DN-gels does not equal the stiffness of articular cartilage. This study investigated whether revised PAMPS/PAAm compositions with lower water content result in stiffness parameters closer to cartilage. DN-gels containing 61, 86 and 90% water were evaluated using two non-destructive, mm-scale indentation test modes: fast-impact (FI) and slow-sinusoidal (SS) deformation. Deformation resistance (dynamic modulus) and energy handling (loss angle) were determined. The dynamic modulus increased with decreasing water content in both testing modes. In the 61% water DN-gel, the modulus resembled that of cartilage (FI-mode: DN-gel = 12, cartilage = 17; SS-mode: DN-gel = 4, cartilage = 1.7 MPa). Loss angle increased with decreasing water content in fast-impact, but not in slow-sinusoidal deformation. However, loss angle was still much lower than cartilage (FI: DN-gel = 5, cartilage = 11; SS: DN-gel = 10, cartilage = 32A degrees), indicating somewhat less ability to dissipate energy. Overall, results show that it is possible to adapt DN-gel composition to produce dynamic stiffness properties close to normal articular cartilage.
  • Tatsuro Goda, Hidemitsu Furukawa, Jian Ping Gong, Kazuhiko Ishihara
    Soft Matter 9 (7) 2166 - 2171 1744-6848 2013/02/21 [Refereed][Not invited]
     
    We investigated the relaxation modes of autocorrelation functions obtained by dynamic light scattering (DLS) of chemically cross-linked zwitterionic hydrogels comprising poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) as the main chain of the network. A time- and space-averaged (i.e., an ensemble-averaged) autocorrelation function was obtained using a home-built DLS apparatus enabling automated positioning of a sample. The equilibrated hydrogels exhibited fast and slow relaxations the former was derived from thermodynamic fluctuations of the polymer network whose cross-link distances were modeled by the Stokes-Einstein equation, whereas the latter depended on cross-linking densities, cross-linker type, and external electrolytes in the hydrogels, suggesting a mesoscopic weak segment-segment interaction driven by electrostatic forces or by the salting-out effect. These observations may aid in the regulation of network integrity and hydration state of the polymer in PMPC hydrogels. © 2013 The Royal Society of Chemistry.
  • 黒川孝幸, 龔剣萍, 室﨑喬之, 野方 靖行
    PEN News Letter 3 (11) 3 - 8 2013/02 [Not refereed][Invited]
  • Katsuhisa Yoshikawa, Nobuto Kitamura, Takayuki Kurokawa, Jian Ping Gong, Yutaka Nohara, Kazunori Yasuda
    BMC MUSCULOSKELETAL DISORDERS 14 56  1471-2474 2013/02 [Refereed][Not invited]
     
    Background: It has been a common belief that articular cartilage tissue cannot regenerate in vivo. Recently, however, we have found that spontaneous hyaline cartilage regeneration can be induced in vivo by implanting a synthetic double-network (DN) hydrogel, which is composed of poly-(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and poly-(N,N'-dimethyl acrylamide) (PDMAAm). However, the mechanism of this phenomenon has not been clarified. Recently, we have found that single-network PAMPS and PDMAAm gels can induce chondrogenic differentiation of ATDC5 cells in vitro even in a maintenance medium. In the in vivo condition, there is a strong possibility that the induction effect of the gel itself is enhanced by some molecules which exist in the joint. We have noticed that the joint fluid naturally contains hyaluronic acid (HA). The purpose of this study is to clarify in vitro effects of supplementation of HA on the differentiation effect of the PAMPS and PDMAAm gels. Methods: We cultured the ATDC5 cells on the PAMPS gel, the PDMAAm gel, and the polystyrene (PS) dish surface with the maintenance medium without insulin for 7 days. HA having a molecular weight of approximately 800 kDa was supplemented into the medium so that the concentration became 0.00, 0.01, 0.10, or 1.00 mg/mL. We evaluated the cultured cells with phase-contrast microscopy and PCR analyses. Results: On the PAMPS gel, supplementation with HA of 0.01 and 0.10 mg/mL significantly increased expression of type-2 collagen mRNA (p = 0.0008 and p = 0.0413) and aggrecan mRNA (p = 0.0073 and p = 0.0196) than that without HA. On the PDMAAm gel, supplementation with HA of 1.00 mg/mL significantly reduced expression of these genes in comparison with the culture without HA (p = 0.0426 and p = 0.0218). Conclusions: The in vitro induction effects of the PAMPS and PDMAAm gels on chondrogenic differentiation of ATDC5 cells are significantly affected by HA, depending on the level of concentration. These results suggested that there is a high possibility that HA plays an important role in the in vivo spontaneous hyaline cartilage regeneration phenomenon induced by the PAMPS/PDMAAm DN gel.
  • Tiffany C. Suekama, Jian Hu, Takayuki Kurokawa, Jian Ping Gong, Stevin H. Gehrke
    ACS MACRO LETTERS 2 (2) 137 - 140 2161-1653 2013/02 [Refereed][Not invited]
     
    A tough and ductile, ultrathin film, double-network (DN), biopolymer-based hydrogel displaying the yielding phenomenon was synthesized from methacrylated chondroitin sulfate (MCS) and polyacrylamide (PAAm). The DN of MCS/PAAm exhibited a failure stress more than 20 times greater than the single network (SN) of either MCS or PAAm and exhibited yielding stresses over 1500 kPa. In addition, the stress-strain behavior with a yielding region was also seen in a hydrogel of MCS and poly(N,N-dimethyl acrylamide) (PDMAAm). By replacing PAAm with PDMAAm, interactions known to toughen networks are removed. This demonstration supports the idea that the brittle/ductile combination is key to the DN effect over specific interactions between the networks. The MCS/PAAm and MCS/PDMAAm DN hydrogels had comparable mechanical properties to the archtypal DN hydrogels of poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS)/PAAm. In addition, these tough and ductile, biopolymer-based, double-network hydrogels demonstrated a substantial yielding region.
  • Yuki Akagi, Jian Ping Gong, Ung-il Chung, Takamasa Sakai
    MACROMOLECULES 46 (3) 1035 - 1040 0024-9297 2013/02 [Refereed][Not invited]
     
    The elastic moduli of elastomeric materials are predicted by the affine or phantom or junction affine network models. Although these models are often used, we do not know the requirement conditions for each model or even the validity of each model. The validation of these models is difficult because of the network heterogeneity. In this study, we tried to evaluate these models using Tetra-PEG gel, which has extremely homogeneous network structure. We performed the stretching and tearing tests, and for the first time, observed the transition between the phantom and affine network models around the overlapping concentration of prepolymers.
  • Abu Bin Ihsan, Tao Lin Sun, Shinya Kuroda, Md. Anamul Haque, Takayuki Kurokawa, Tasuku Nakajima, Jian Ping Gong
    JOURNAL OF MATERIALS CHEMISTRY B 1 (36) 4555 - 4562 2050-750X 2013 [Refereed][Not invited]
     
    Our recent study has revealed that neutral polyampholytes form tough physical hydrogels above a critical concentration C-m,C-c by forming ionic bonds of wide strength distribution. In this work, we systematically investigate the behavior of a polyampholyte system, poly(NaSS-co-DMAEA-Q), randomly copolymerized from oppositely charged monomers, sodium p-styrenesulfonate (NaSS) and acryloyloxethyltrimethylammonium chloride (DMAEA-Q) without and with a slight chemical cross-linking. A phase diagram of formulation has been constructed in the space of monomer concentration C-m and cross-linker density C-MBAA. Three phases are observed for the as-synthesized samples: homogeneous solution at dilute C-m, phase separation at semi-dilute C-m, and homogenous gel at concentrated C-m. Above a critical C-m,C-c, the polyampholyte forms a supramolecular hydrogel with high toughness by dialysis of the mobile counter-ions, which substantially stabilizes both the intra-and inter chain ionic bonds. The presence of the chemical cross-linker (C-MBAA > 0) brings about a shift of the tough gel phase to lower C-m,C-c. The tough polyampholyte gel, containing similar to 50 wt % water, is highly stretchable and tough, exhibits fracture stress of sigma(b) similar to 0.4 MPa, fracture strain of epsilon(b) similar to 30, and the work of extension at fracture W-ext similar to 4 MJ m(-3). These values are at the level of most tough soft materials. Owing to the reversible ion bonds, the poly(NaSS-co-DMAEA-Q) gels also exhibit complete self-recovery (100%) and high fatigue resistance upon repeated large deformation.
  • Takayuki Murosaki, Takaya Noguchi, Yasuyuki Nogata, Jian Ping Gong
    KOBUNSHI RONBUNSHU 70 (7) 326 - 330 0386-2186 2013 [Refereed][Invited]
     
    In this study, we investigate the settlement behavior of barnacle cyprid larvae on several kinds of natural polymer gels. 24 well plates were used for all of the settlement tests. The results show that several natural polymer gels have antifouling activities against barnacle settlement In particular, agarose gels show high antifouling performance. The antifouling activities of a K-carrageenan gel is relatively low compared with other natural polymer gels, however it shows high release activity against settled barnacles. Furthermore, the results from the settlement test of agarose coated wells indicate that antifouling properties of hydrogels consist of inhibition, anti-adhesion, and easy release effects.
  • Haiyan Yin, Taigo Akasaki, Tao Lin Sun, Tasuku Nakajima, Takayuki Kurokawa, Takayuki Nonoyama, Toshio Taira, Yoshiyuki Saruwatari, Jian Ping Gong
    JOURNAL OF MATERIALS CHEMISTRY B 1 (30) 3685 - 3693 2050-750X 2013 [Refereed][Not invited]
     
    Polyzwitterionic materials, which have both cationic and anionic groups in the polymeric repeat unit, show excellent anti-biofouling properties and are drawing more attention in the biomedical field. In this study, we have successfully synthesized novel single network hydrogels and double network (DN) hydrogels from the zwitterionic monomer, N-(carboxymethyl)-N,N-dimethyl-2-(methacryloyloxy) ethanaminium, inner salt (CDME). The polyCDME (PCDME) single network hydrogel behaves like a hydrophilic neutral hydrogel and its properties are not sensitive to temperature, pH, or ionic strength over a wide range. DN hydrogels using the poly(2-acrylamido-2-methylpropanesulfonic) (PAMPS) as the first network and PCDME as the second network, having a Young's modulus of 0.2-0.9 MPa, possess excellent mechanical strength (fracture stress: 1.2-1.4 MPa, fracture strain: 2.2-6.0 mm/mm) and toughness (work of extension at fracture: 0.9-2.4 MJ m(-3)) depending on the composition ratio of PCDME to PAMPS. The strength and toughness of the optimized PAMPS/PCDME DN is comparable to the normal PAMPS/PAAm DN hydrogels that use poly(acrylamide) (PAAm) as the second network. By macrophage adhesion test, both the PCDME hydrogels and the PAMPS/PCDME DN hydrogels have shown excellent anti-biofouling properties. These results demonstrate that the PCDME-based DN hydrogels have high potential as a novel soft and wet biomaterial.
  • Daisuke Inoue, Arif Md Rashedul Kabir, Hiroyuki Mayama, Jian Ping Gong, Kazuki Sada, Akira Kakugo
    SOFT MATTER 9 (29) 7061 - 7068 1744-683X 2013 [Refereed][Not invited]
     
    The microtubule (MT)-kinesin system is a promising candidate for constructing artificial biomachines. The active self-organisation (AcSO) method has been developed to integrate MT filaments into highly organised assembled structures. The creation of ring-shaped MT assemblies is one of the outcomes of the organisation process and holds prospects for use in future nano-technological applications. However, making use of ring-shaped MT assemblies in practical applications requires further control of the size of these assemblies, which has not yet been addressed. In this work, we demonstrated AcSO of MTs in a stepwise manner inside an inert atmosphere. We show that in an inert atmosphere, AcSO could be performed several times (at least nine times), and as a result, this method successfully increased the thickness of ring-shaped MT assemblies.
  • Md Anamul Haque, Takayuki Kurokawa, Jian Ping Gong
    SOFT MATTER 9 (21) 5223 - 5230 1744-683X 2013 [Refereed][Not invited]
     
    We demonstrate, for the first time, a distinct change of the bulk properties of a hydrogel based on the lamellar-micelle transition. The hydrogel consists of thousands of periodical stacks of bilayer membranes, poly(dodecyl glyceryl itaconate) (PDGI), inside a dilute polyacrylamide network. Along with a bright structure color, the hydrogel exhibits a strong anisotropy in its bulk properties. By grafting a short chain polymer lipid, poly(ethylene glycol) dodecyl ether (C12EO23), to the bilayer membrane, sharp changes in the structure color, swelling and modulus of the hydrogel are observed in a narrow C12EO23 concentration range. These changes are ascribed to the structure transition of the single domain lamellar phase to the multi-domain micelle phase of PDGI, induced by the excluded volume effect of two dimensionally grafted poly(ethylene glycols) (PEG). By controlling the water permeable nano-channels formed during the structure transition, a specific molecular diffusion and recognition are demonstrated. This lamellar bilayer hydrogel could be a new insight into the lipid bilayer system to investigate the nature of biological membranes by the bulk behaviors of hydrogels.
  • Hidetoshi Matsuda, Nobuto Kitamura, Takayuki Kurokawa, Kazunobu Arakaki, Jian Ping Gong, Fuminori Kanaya, Kazunori Yasuda
    BMC MUSCULOSKELETAL DISORDERS 14 50  1471-2474 2013/01 [Refereed][Not invited]
     
    Background: A double-network (DN) gel, which is composed of poly(2-acrylamido-2-methylpropanesulfonic acid) and poly(N,N'-dimethyl acrylamide), can induce hyaline cartilage regeneration in vivo in a large osteochondral defect. The purpose of this study was to clarify the influence of the thickness of the implanted DN gel on the induction ability of hyaline cartilage regeneration. Methods: Thirty-eight mature rabbits were used in this study. We created an osteochondral defect having a diameter of 4.3-mm in the patellofemoral joint. The knees were randomly divided into 4 groups (Group I: 0.5-mm thick gel, Group II: 1.0-mm thick gel, Group III: 5.0-mm thick gel, and Group IV: untreated control). Animals in each group were further divided into 3 sub-groups depending on the gel implant position (2.0-, 3.0-, or 4.0-mm depth from the articular surface) in the defect. The regenerated tissues were evaluated with the Wayne's gross and histological grading scales and real time PCR analysis of the cartilage marker genes at 4 weeks. Results: According to the total Wayne's score, when the depth of the final vacant space was set at 2.0 mm, the scores in Groups I, II, and III were significantly greater than that Group IV (p < 0.05), although there were no significant differences between Groups I and IV at a 3.0-mm deep vacant space. The expression levels of type-2 collagen in Groups II and III were significantly higher (p < 0.05) than that in Group IV. Conclusions: The 1.0-mm thick DN gel sheet had the same ability to induce hyaline cartilage regeneration as the 5.0-mm thick DN gel plug. However, the induction ability of the 0.5-mm thick sheet was significantly lower when compared with the 1.0-mm thick gel sheet. The 1.0-mm DN gel sheet is a promising device to establish a cell-free cartilage regeneration strategy that minimizes bone loss from the gel implantation.
  • Tatsuro Goda, Hidemitsu Furukawa, Jian Ping Gong, Kazuhiko Ishihara
    Soft Matter 9 (7) 2166 - 2171 1744-683X 2013/01 [Refereed][Not invited]
  • Tasuku Nakajima, Takayuki Kurokawa, Saika Ahmed, Wen-li Wu, Jian Ping Gong
    SOFT MATTER 9 (6) 1955 - 1966 1744-683X 2013 [Refereed][Not invited]
     
    Previously we revealed that the high toughness of double network hydrogels (DN gels) derives from the internal fracture of the brittle network during deformation, which dissipates energy as sacrificial bonds. In this study, we intend to elucidate the detailed internal fracture process of DN gels. We quantitatively analysed the tensile hysteresis and re-swelling behaviour of a DN gel that shows a well-defined necking and strain hardening, and obtained the following new findings: (1) fracture of the 1st network PAMPS starts far below the yielding strain, and 90% of the initially load-bearing PAMPS chains already break at the necking point. (2) The dominant internal fracture process occurs in the necking and hardening region, although the softening mainly occurs before necking. (3) The internal fracture efficiency is very high, 85% of the work is used for the internal fracture and 9% of all PAMPS chains break at sample failure. (4) The internal fracture is anisotropic, fracture occurs perpendicular to the tensile direction, in preference to the other two directions, but the fracture anisotropy decreases in the hardening region. Results (1) and (2) are in agreement with a hierarchical structural model of the PAMPS network. Based on these findings, we present a revised description of the fracture process of DN gels.
  • Jian Hu, Takayuki Kurokawa, Tasuku Nakajima, Tao Lin Sun, Tiffany Suekama, Zi Liang Wu, Song Miao Liang, Jian Ping Gong
    Macromolecules 45 (23) 9445 - 9451 0024-9297 2012/12/11 [Refereed][Not invited]
     
    Double-network hydrogels (DN gels) have aroused considerable interest because of their excellent mechanical strength and toughness, low sliding friction, good biocompatibility, as well as wide tunability in components. By revisiting DN gels, we provide an ingenious way to fabricate a kind of strong and tough microgel-reinforced hydrogels (MR gels), that densely cross-linked polyelectrolyte microgels of poly(2-acrylamido-2-methylpropanesulfonic sodium) (PNaAMPS) (replacing the densely cross-linked PNaAMPS macro-network for conventional DN gels) are incorporated into sparsely cross-linked neutral polyacrylamide (PAAm) matrix. The structure of MR gels can be considered as a two-phase composite, where the disperse phase is the rigid DN microgels, and the continuous phase is the soft PAAm matrix. Similar to DN gels, MR gels show the irreversible energy dissipation in the hysteresis measurement, demonstrating the permanent fracture of the brittle PNaAMPS phase. Thus, the discontinuous brittle phase also serves as sacrificial bonds. Through quantitative comparison of the hysteresis curves with DN gels and monitoring the morphology change of the embedded microgels in MR gels during the real-time stretching process, we conclude that the DN microgels in MR gels show four times higher in fracture efficiency of the sacrificial bonds than bulk DN gels at the same strain, as a result of the stress concentration around the microgels. © 2012 American Chemical Society.
  • Tasuku Nakajima, Hitomi Sato, Yu Zhao, Shinya Kawahara, Takayuki Kurokawa, Kazuyuki Sugahara, Jian Ping Gong
    ADVANCED FUNCTIONAL MATERIALS 22 (21) 4426 - 4432 1616-301X 2012/11 [Refereed][Not invited]
     
    Double-network hydrogels (DN gels), despite their high water content, are the strongest and toughest soft and wet materials available. However, in conventional DN gels, which show extraordinarily high mechanical performance comparable to that of industrial rubbers, the first network must be a strong polyelectrolyte and this requirement greatly hinders the widespread application of these gels. A general method involving the use of a molecular stent for the synthesis of tough DN gels using any hydrophilic polymer as the first network is reported. This is the first reported method for the synthesis of tough DN gels using various neutral or weak polyelectrolyte hydrogels as the first network. This method helps extend the DN gel concept to various functional polymers and may increase the number of applications of hydrogels in various fields.
  • Munehiro Ogawa, Nobuto Kitamura, Takayuki Kurokawa, Kazunobu Arakaki, Yasuhito Tanaka, Jian Ping Gong, Kazunori Yasuda
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 100A (9) 2244 - 2251 1549-3296 2012/09 [Not refereed][Invited]
     
    The purpose of this study was to determine the in vivo cartilage induction effect of the poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) single-network (SN) gel and poly(N,N'-dimethyl acrylamide) (PDMAAm) SN gel in comparison with that of the PAMPS/PDMAAm double-network (DN) gel. An osteochondral defect created in rabbit trochlea was treated with PAMPS/PDMAAm DN, PAMPS SN, or PDMAAm SN gel implantation or left untreated. The gel was implanted into the defect so that a 2-mm depth remained. The defects were examined by histologic and immunohistochemical evaluations, surface assessment using confocal laser scanning microscopy, and real-time polymerase chain reaction analysis at 4 weeks. Samples were quantitatively evaluated with a scoring system reported by Wayne et al. The PAMPS/PDMAAm DN gel-implanted defect was filled with the hyaline-like cartilage tissue. The PAMPS SN gel-implanted defect was filled inhomogenously with hyaline/fibrocartilage tissue. The histology score of the defect treated with PAMPS/PDMAAm DN gel was significantly higher than those treated with PAMPS and PDMAAm SN gels, and the untreated defect (p = 0.0408, p < 0.0001, and p < 0.0001, respectively) and the scores of the defect treated with PAMPS SN gel were significantly higher than those treated with PDMAAm SN gel and the untreated defect (p = 0.0026 and p = 0.0026, respectively). These results suggested that the PAMPS SN gel has an ability that can induce hyaline cartilage regeneration in vivo, but that the PDMAAm SN gel does not. The current study indicates that the chondrogenic potential of a negatively charged PAMPS gel component plays an important role in the cartilage regeneration ability of the PAMPS/PDMAAm DN gel in vivo. (c) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A: 22442251, 2012.
  • Zii Liang Wu, Takayuki Kurokawa, Jian Ping Gong
    POLYMER JOURNAL 44 (6) 503 - 511 0032-3896 2012/06 [Refereed][Not invited]
     
    Designing hydrogels with self-assembled or self-organized structures has become an attractive field of research because these hydrogels usually have robust functions and promising applications, such as in artificial tissues and optical sensors. However, the self-organized structures developed in synthetic hydrogels via molecular self-assembly are generally limited to the sub-micrometer or micrometer level, which is far from the related scale achieved in biological tissues. Therefore, it is desirable to create macroscopically ordered structures in hydrogels; these structures should greatly improve the material's functionalities, such as their optical properties. In this review, we generally introduce our recent studies on the synthesis of hydrogels with macroscopic-scale liquid crystal structures based on the self-assembly of a semi-rigid polyanion, poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT). Upon electrostatic interaction with multivalent cations or polycations, PBDT molecules form semi-rigid complexes or mesoscopic bundles that further self-assemble into macroscopic organized structures and are frozen by the subsequent gelation process. We have developed physical hydrogels with centimeter-scale anisotropic structures, polycationic hydrogels with millimeter-scale cylindrically symmetric structures and plate gels with cubic-packed concentric domains. This work should contribute to the development of macroscopic self-organized structures in hydrogel materials with specific functions. Polymer Journal (2012) 44, 503-511; doi: 10.1038/pj.2012.74; published online 25 April 2012
  • Jian Hu, Takayuki Kurokawa, Kenta Hiwatashi, Tasuku Nakajima, Zi Liang Wu, Song Miao Liang, Jian Ping Gong
    MACROMOLECULES 45 (12) 5218 - 5228 0024-9297 2012/06 [Refereed][Not invited]
     
    In this work, the mechanical behavior of sparsely cross-linked, neutral polyacrylamide (PAAm) hydrogels containing densely cross-linked polyelectrolyte microgels of poly(2-acrylamido-2-methylpropanesulfonic sodium) (PNaAMPS) were studied systematically by varying the formulations. The microgel-reinforced (MR) hydrogels have a two-phase composite structure, where the disperse phase is the rigid double-network (DN) microgels, and the continuous phase is the soft PAAm matrix. At the optimal formulation, the MR gels showed high mechanical strength and toughness, comparable to conventional DN hydrogels. The two critical parameters for the substantial enhancement of mechanical strength and toughness of MR gels are the concentration of PNaAMPS microgel and the molar ratio of the PAAm to the PNaAMPS in the microgel phase. Selective dyeing of the embedded microgels in MR gels allowed for visualization of the deformation of microgels, and we found that the local strain of microgels was much smaller than the global strain applied on MR gels; this indicates that isostress model (Reuss's model) is more suitable than isostrain model (Voigt's model) for this composite system.
  • Songmiao Liang, Jian Flu, Zi Liang Wu, Takayuki Kurokawa, Jian Ping Gong
    MACROMOLECULES 45 (11) 4758 - 4763 0024-9297 2012/06 [Refereed][Not invited]
     
    Using a thin film double-network (DN) hydrogels of 100 mu m thickness, the behaviors of DN gels, from poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) as the first network and polyacrylamide (PAAm) as the second network, swelled in poly(ethylene glycol) (PEG) aqueous solution of short molecular weight (M-w: 400 g/mol) are investigated. Comparing with the conventional DN gels that are swelled in water, the toughness of the DN gels swelled in PEG solution is largely enhanced, as revealed by the tensile test and tearing test. Furthermore, a transition in the crack propagation dynamics, from the steady-state mode in water to the stick-slip instability mode in PEG solution, is observed in the tearing test. The morphology around the crack front of the DN gels also changes with the presence of PEG, and characteristic triangular-like damage patterns are observed. Besides, spicule-like structures are observed on the fractured surface, either in water or in PEG solution. The PEG-induced behaviors are associated with the molecular interaction of PEG to polyacrylamide, the second ductile network of the DN gels.
  • Arif Md Rashedul Kabir, Daisuke Inoue, Akira Kakugo, Kazuki Sada, Jian Ping Gong
    POLYMER JOURNAL 44 (6) 607 - 611 0032-3896 2012/06 [Refereed][Not invited]
     
    Microtubule-kinesin system is considered as a building block for the construction of artificial biomachines, and active self-organization of microtubules has been used to integrate their structural organization and achieve amplified functions similar to those observed in natural systems. However, the short lifetime of assembled structures has limited their use in organized systems. In the present study, we demonstrated that the use of an inert atmosphere in the self-organization of microtubules allows the assembled structures to remain active for a prolonged period of time (10 times longer). The longer lifetime achieved in the present study will facilitate the development of assembled microtubules for designing biomolecular motor-based efficient artificial biomachines with prolonged lifetimes. Polymer Journal (2012) 44, 607-611; doi:10.1038/pj.2012.26; published online 4 April 2012
  • Sun TaoLin, Wu ZiLiang, Gong JianPing
    SCIENCE CHINA-CHEMISTRY 55 (5) 735 - 742 1674-7291 2012/05 [Refereed][Not invited]
     
    Poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT), a kind of liquid-crystalline (LC) molecule, has high molecular weight, negative charge and a semi-rigid structure. The aqueous solution of PBDT shows nematic liquid crystalline state above a critical PBDT concentration, C (LC)*, of 2 wt%-3wt%. Different from the flexible polyelectrolyte, PBDT shows a variety of self-assembling structures in aqueous solution with and without salt due to the semi-rigid nature and highly charged property. In addition, the hydrogels with ordered structure are developed by polymerizing a cationic monomer N-[3-(N,N-dimethylamino) propyl] acrylamide methyl chloride quarternary (DMAPAA-Q) in the presence of a small amount of PBDT below the C (LC)*. During the polymerization of cationic monomer, the polycations form a complex with semi-rigid PBDT through electrostatic interaction; these complexes self-assemble into ordered structures that are frozen in the hydrogel. Several different structures, including the anisotropic, dual network-like structure, and cylindrically symmetric structure, with various length scales from micrometer to millimeter, are observed. The hydrogels with ordered liquid crystalline assemblies and particular optical properties should promise applications in many fields, such as in bionics, tissue engineering, and mechano-optical sensors.
  • Md. Anamul Haque, Takayuki Kurokawa, Jian Ping Gong
    POLYMER 53 (9) 1805 - 1822 0032-3861 2012/04 [Refereed][Not invited]
     
    The double network (ON) technique, developed by authors' group, provides an innovative and universal pass way to fabricate hydrogels with super high toughness comparable to rubbers. The excellent mechanical performances of ON hydrogels originate from the specific combination of two networks with contrasting structures. The first brittle network serves as sacrificial bonds, which breaks into small clusters to efficiently disperse the stress around the crack tip into the surrounding damage zone, while the second ductile polymer chains act as hidden length, which extends extensively to sustain large deformation. Based on the principle of ON hydrogel, the author's group recently has developed several novel systems and techniques, which has greatly expanded the practical accessibility of ON technique for practical use. The ON principle and the ON gel have already attracted much attention in the soft matter community. Inspired by the ON principle, many research groups have also designed and developed some innovative hydrogels with large enhancement in their mechanical strength and toughness. Some tough hydrogels fabricated by the ON technique also exhibit good biocompatibility and low friction resistance with promising prospective in industrial and medicine fields, especially for load-bearing artificial soft tissues such as artificial cartilage. In this feature article, we address the major concept and toughening mechanism of ON gel, then we describe some recent novel hydrogel systems based on the ON concept, and finally the applicability of ON gel as soft biomaterials is discussed. (C) 2012 Elsevier Ltd. All rights reserved.
  • 生体分子モーターの自発的高次構造形成
    敷中一洋, 角五 彰, 龔 剣萍
    液晶 16 (1) 45 - 51 2012/01 [Not refereed][Invited]
  • Md Anamul Haque, Takayuki Kurokawa, Jian Ping Gong
    SOFT MATTER 8 (31) 8008 - 8016 1744-683X 2012 [Refereed][Invited]
     
    In this highlight, we introduce a novel anisotropic hydrogel with a perfect 1D photonic crystal structure based on the uniaxial alignment of lamellar bilayers. The gel was synthesized in a one-pot polymerization from a precursor solution containing a polymerizable surfactant (dodecyl glyceryl itaconate: DGI), acrylamide, and a cross-linker. By applying shear flow to the precursor solution, lamellar bilayers of self-assembled DGI were aligned in one direction parallel to the substrate surface. The polymerized lamellar bilayers were stacked periodically and entrapped in the polyacrylamide matrix to give a hydrogel with a 1D photonic crystal structure. This hydrogel, containing 94-95 wt% water and 1.0-1.5 wt% bilayer molecules, shows perfect one-dimensional swelling, strong anisotropy in the elastic modulus, and magnificent structural color by multilayer interference according to Bragg's law of diffraction. Owing to the softness and large deformability, the color of the gel can be reversibly tuned by both compressive and tensile mechanical stimuli over the entire wavelength range of visible color. The single-domain lamellar bilayer not only diffracts light but also serves as a reversible sacrificial bond that dissociates upon deformation, exhibiting large hysteresis as an energy dissipation mechanism, which gives the gel high tensile strength and fatigue resistance. Both the molecular dissociation and lipid-like mobile nature of DGI molecules in the bilayers dramatically enhance the resistance against crack propagation by the formation of extraordinary blunting, which gives the gel an extraordinarily high toughness.
  • Kiyotaka Shigehara, Hiroki Kudoh, Saori Mori, Yoshiki Tamura, Akira Kakugo, Ryuzo Kawamura, Hidemitsu Furukawa, Jian Ping Gong, Hiroyasu Masunaga, Tomomi Masui, Satoshi Koizumi, Kazuhiro Shikinaka
    SOFT MATTER 8 (45) 11544 - 11551 1744-683X 2012 [Refereed][Not invited]
     
    In a long capillary cell with temperature gradient, tubulin dimers with alpha and beta subunits polymerized according to the preferential polarity, i.e., the anisotropic spiral addition of the dimers to the beta-terminated "plus end" dominated the formation of microtubules. As the result, the helical hollow cylinders generated the oriented nematic liquid crystalline structure with centimeter-length. In the next stage, where microtubules were under the partial polymerization/depolymerization equilibrium due to the concentration fluctuation, the dynamic rearrangement of microtubules such as their shortening (depolymerization) and subsequent tilting of orientation axis caused the structural change from the oriented nematic liquid crystalline structure to some giant spiral structure which was subjected by the ordered dipole and the helical chirality of microtubules.
  • Arif Md Rashedul Kabir, Shoki Wada, Daisuke Inoue, Yoshiki Tamura, Tamaki Kajihara, Hiroyuki Mayama, Kazuki Sada, Akira Kakugo, Jian Ping Gong
    SOFT MATTER 8 (42) 10863 - 10867 1744-683X 2012 [Refereed][Not invited]
     
    Biopolymers such as actin, microtubules and DNA are well known for their fascinating in vivo self-organization phenomena. Considerable efforts have been devoted to mimicking their organization process in vitro that produced ring-shaped or toroid structures in an irreversible manner. However, understanding the factors that lead to formation of such assembled structures deserves more investigation to achieve a unified insight into the assembly process, particularly of the microtubules. Here, we report an active assembly process of microtubules (MTs) at an air-buffer interface that resulted in ring-shaped microtubule structures with a narrow size distribution and a high yield. Using an "air-buffer interface control system" combined with the newly developed "inert chamber system (ICS)" we have also successfully observed the reversible conformational transition between ring-and linear-shaped microtubules at the air-buffer interface. This is the first ever direct in situ observation of a reversible assembly process of MTs and probably provides us with valuable discernment to understand the in vivo organizational behavior of biopolymers.
  • Md Arifuzzaman, Zi Liang Wu, Takayuki Kurokawa, Akira Kakugo, Jian Ping Gong
    SOFT MATTER 8 (31) 8060 - 8066 1744-683X 2012 [Refereed][Not invited]
     
    A millimeter-scale periodic structure is created in a polyelectrolyte hydrogel by the rapid-heterogeneous swelling process, and is frozen by the polyion complexation of the polyelectrolyte network with the oppositely charged, semi-rigid polyelectrolyte. The hydrogel is synthesized from a cationic monomer, N-[3-(N,N-dimethylamino)propyl] acrylamide methyl chloride quaternary (DMAPAA-Q), in the presence of a small amount of the oppositely charged poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) that has a semi-rigid nature. During the swelling process, surface creasing due to the large mismatching of swelling degree between the surface layer and the inner one of the poly DMAPAA-Q (PDMAPAA-Q) gel occurs, which induces highly oriented semi-rigid PBDT molecules along the tensile direction of the crease pattern. To accompany the evolution of surface creasing, a lattice-like periodic birefringence pattern is formed, which is frozen permanently by the strong polyion complex formation, even after the surface instability pattern of the gel disappears completely throughout the dynamic coalescence. In this work we rationally clarified that formation of such a long-range ordered non-equilibrium structure in the polyelectrolyte hydrogel by the rapid-heterogeneous swelling process requires the following three indispensable conditions: (i) swelling-induced surface creasing; (ii) polyion complex formation; and (iii) a semi-rigid or rigid dopant. This sort of non-equilibrium structure formation mechanism may help understand how biomacromolecules that are rigid polyelectrolytes, such as deoxyribonucleic acid, microtubules and actin filaments, form rich architectures during the growth of biological organs.
  • Takayuki Murosaki, Nafees Ahmed, Jian Ping Gong
    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 12 (6) 064706  1468-6996 2011/12 [Refereed][Invited]
     
    Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet 'hydrogel'. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris.
  • Ryuzo Kawamura, Akira Kakugo, Kazuhiro Shikinaka, Yoshihito Osada, Jian Ping Gong
    SMART MATERIALS AND STRUCTURES 20 (12) 124007  0964-1726 2011/12 [Refereed][Not invited]
     
    Microtubule (MT) and kinesin are rail and motor proteins that are involved in various moving events of eukaryotic cells in natural systems. In vitro, the sliding motion of microtubules (rail) can be reproduced on a kinesin (motor protein)-coated surface coupled with adenosine triphosphate (ATP) hydrolysis, which is called a `motility assay'. Based on this technique, a method was recently established to form MT assemblies by an active self-assembly (AcSA) process, in which MTs are crosslinked during a sliding motion on a kinesin-coated surface. Streptavidin (ST) was employed as glue to crosslink biotin-labeled MTs. Various shapes, sizes, and motilities were formed with the AcSA MT assemblies, depending on the initial conditions. In this paper, we briefly review our recent work on the formation of MT assemblies on a kinesin-coated surface.
  • Zi Liang Wu, Takayuki Kurokawa, Jian Ping Gong
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 84 (12) 1295 - 1311 0009-2673 2011/12 [Refereed][Not invited]
     
    The double-network hydrogels (DN gels), developed by our group in 2003, have attracted increasing attention clue to their excellent mechanical performance and unique fracture mechanism. The anomalously large fracture energy of DN gels up to 2200J m(-2) originates from the specific combination of two networks with contrasting properties. The first brittle network serves as sacrificial bonds, which breaks into small clusters to efficiently disperse the stress around the crack tip into the surrounding damage zone, while the second ductile polymer chains act as hidden length, which extends extensively to sustain large deformation. The DN gels also exhibit good biocompatibility and low friction resistance. Owing to these superior properties. DN gels possess promising prospective in industrial and medicine fields, especially for load-bearing artificial soft tissues such as artificial cartilage. However, there are several critical problems limiting the practical applications of DN gels, such as how to produce tough artificial tissue with complex shapes or bond a gel to a solid substrate. To address these specific issues, we have developed new systems and techniques based on the DN principle. These achievements, including synthesis of ultrathin DN gels, bonding of one gel to another gel or solid substrate, free-shaping of DN gels, enhancing typical single network gels by creating a DN structure, will be briefly introduced in this account paper. We believe that these new techniques will substantially promote the practical applications of ON hydrogels and extent the DN principle to other systems.
  • Md. Anamul Haque, Takayuki Kurokawa, Gen Kamita, Youfeng Yue, Jian Ping Gong
    CHEMISTRY OF MATERIALS 23 (23) 5200 - 5207 0897-4756 2011/12 [Refereed][Not invited]
     
    In this work, we report a rubberlike elastic hydrogel containing microdomains of bilayers periodically stacked into the polymer network that satisfy the Bragg's law of diffraction. The rubberlike elastic hydrogel has been synthesized by applying double network principle into a viscoelastic hydrogel containing single-domain macroscopic lamellar bilayer. The hydrogel is able to tune the magnificent structural color reversibly over the entire wavelength range of visible spectrum as fast as the uniaxial tensile stretching and compressive deformation are applied and released. Owing to the strength, softness, and rubberlike elastic deformability, the tunable hydrogel can be used extensively to design a new class of soft tactile sensor as an advanced stress sensor that is able to detect a local deformation of a complicated force field.
  • M. Anamul Haque, Takayuki Kurokawa, Gen Kamita, J. Ping Gong
    MACROMOLECULES 44 (22) 8916 - 8924 0024-9297 2011/11 [Refereed][Not invited]
     
    We report the extraordinary toughness, hysteresis, self-recovery, and persistent fatigue resistance of an anisotropic hydrogel with single-domain lamellar structure, consisting of periodical stacking of several thousands of rigid, hydrophobic bilayers in the ductile, hydrophilic polymer matrix. The stratified lamellar bilayers not only diffract light to exhibit magnificent structural color but also serve as reversible sacrificial bonds that dissociate upon deformation, exhibiting large hysteresis as an energy dissipation mechanism. Both the molecular dissociation and lipid-like mobile nature of bilayers dramatically enhance the resistance to crack propagation by suppressing the stress concentration at the crack tip with the formation of extraordinary crack blunting. This unique toughening phenomenon could allow deep insight into the toughening mechanism of the hydrogel-like soft materials such as biological soft tissues.
  • Yukihiro Nakano, Takayuki Kurokawa, Miao Du, Jian Liu, Taiki Tominaga, Yoshihito Osada, Jian Ping Gong
    MACROMOLECULES 44 (22) 8908 - 8915 0024-9297 2011/11 [Refereed][Not invited]
     
    We study the sliding friction of poly(vinyl alcohol) (PVA) gel against glass substrate in hyaluronan (HA) aqueous solution with various concentrations and two molecular weights. The frictional stress decreases with increase of concentration of HA at low sliding velocity, and the lowest friction appears in HA 10c* (c* is the overlap concentration) solution; after that, it increases slightly with the concentration. By assuming that a continuous HA lubricant layer is formed at the interface, which screens PVA adsorption to substrate, we estimate the thickness of the lubrication film in concentrated HA solution. In addition, we perform frictional measurement in poly(ethylene oxide) (PEO) aqueous solutions and proteoglycan solutions. By comparing the frictional behavior with that in HA solutions, we observe a universal relationship between the zero-shear rate viscosity of polymer solution and the friction at low sliding velocity region, regardless the change in the lubricating polymer species.
  • Arif Md. Rashedul Kabir, Daisuke Inoue, Akira Kakugo, Akiko Kamei, Jian Ping Gong
    LANGMUIR 27 (22) 13659 - 13668 0743-7463 2011/11 [Refereed][Not invited]
     
    Over the last few decades, the in vitro motility assay has been performed to probe the biophysical and chemo-mechanical properties as well as the self-organization process of biomolecular motor systems such as actin - myosin and microtubule - kinesin. However, aggression of the reactive oxygen species (ROS) and concomitant termination of the activity of biomolecular motors during investigation remains a drawback of this assay. Despite enzymatic protection that makes use of a combination of glucose, glucose oxidase, and catalase, the active lifetime of biomolecular motors is found to be only a few hours and this short lifetime restricts further study on those systems. We have solved this problem by using a newly developed system of the in vitro motility assay that is conducted in an inert nitrogen gas atmosphere free of ROS. Using microtubule kinesin as a model system we have shown that our system has prolonged the active lifetime of the biomolecular motor until several days and even a week by protecting it from oxidative damage.
  • Arif Md. Rashedul Kabir, Akira Kakugo, Jian Ping Gong, Yoshihito Osada
    MACROMOLECULAR BIOSCIENCE 11 (10) 1314 - 1324 1616-5187 2011/10 [Not refereed][Invited]
     
    Biological motors, driven by the conversion of chemical energy into mechanical energy, are much more efficient than man-made machines. The development of such efficient biomimetic motor systems in vitro is currently a vital need. However, great difficulty lies in how to integrate the sophisticated functions of the constituent components to obtain a performance as in the case of natural living systems. Based on 'active' and 'passive' self-organization principles, it has been demonstrated that the functions of motor protein systems can be integrated to obtain complex hierarchical structures that can work as actuators. Most of the works discussed here concern two-dimensional behavior, and recent works aim to explore the three-dimensional features of such artificial bio-mechanical systems.
  • Akira Kakugo, Arif Md. Rashedul Kabir, Natsuki Hosoda, Kazuhiro Shikinaka, Jian Ping Gong
    BIOMACROMOLECULES 12 (10) 3394 - 3399 1525-7797 2011/10 [Refereed][Not invited]
     
    The microtubule (MT)-kinesin system has been propose as the building block of biomolecular motor based artificial biomachines. Considerable efforts have been devoted to integrate this system that produced a variety of ordered structures including the ring-shaped MT assembly which is being considered as a promising candidate for the further development of the biomachines. However, lack of proper knowledge that might help tune the direction of Motion of ring-shaped microtubule assembly from counterclockwise to clockwise direction, and vice versa, significantly restricted their potential applications. We report our success in controlling the direction of rotational motion of ring-shaped MT assembly by altering the preparation conditions of microtubules. The change in the direction of rotation of MT rings could be interpreted in terms of the accompanied structural rearrangement of the MT lattice. For achieving handedness-regulated efficient biomachines having tunable asymmetric property, our study will be significantly directive.
  • Jian Hu, Kenta Hiwatashi, Takayuki Kurokawa, Song Miao Liang, Zi Liang Wu, Jian Ping Gong
    MACROMOLECULES 44 (19) 7775 - 7781 0024-9297 2011/10 [Refereed][Not invited]
     
    The poor mechanical properties remain the largest barrier to traditional synthetic hydrogels for extensive practical applications, such as tissue scaffolds. In this work, we have synthesized the hydrogel films in the presence of microgel precursors of various chemical species with different charges. The hydrogels fabricated have a novel two-phase composite structure, where the continuous phase is a loosely cross-linked polyacrylamide (PAAm) matrix and the disperse phase is virtually double-network (DN) microgels. Named as microgel-reinforced (MR) hydrogels, they exhibited dramatic enhancement in mechanical strength and toughness, in comparison to the hydrogels with no microgels. MR hydrogels showed the comparable mechanical properties with the conventional bicontinuous DN hydrogels. By visualizing the embedded microgels before, during, and after the elongation, mesoscale fractures of the microgels phase were confirmed, which should effectively blunt the crack and enhance the fracture propagation resistance. Therefore, we conclude that the essential reinforcement principle of MR gels roots in the sacrificial bonds effect contributed by the microgels. This work provides a novel universal pathway to synthesize hydrogel thin films with high strength and toughness from various microgels and may open a new avenue for the application of hydrogels in various fields, such as fast responsive actuators, fuel cell films, wound dressings, etc.
  • Markus P. Arnold, Alma U. Daniels, Sarah Ronken, Helena Ardura Garcia, Niklaus F. Friederich, Takayuki Kurokawa, Jian P. Gong, Dieter Wirz
    CARTILAGE 2 (4) 374 - 383 1947-6035 2011/10 [Refereed][Not invited]
     
    Background: In focal repair of joint cartilage and meniscus, initial stiffness and strength of repairs are generally much less than surrounding tissue. This increases early failure potential. Secure primary fixation of the repair material is also a problem. Acrylamide polymer double-network (DN) hydrogels are candidate-improved repair materials. DN gels have exceptional strength and toughness compared to ordinary gels. This stems from the double-network structure in which there is a high molar ratio of the second network to the first network, with the first network highly crosslinked and the second loosely crosslinked. Previous studies of acrylic PAMPS/PDMAAm and PAMPS/PAAm DN gels demonstrated physicochemical stability and tissue compatibility as well as the ability to foster cartilage formation. Methods: Mechanical properties related to surgical use were tested in 2 types of DN gels. Results: Remarkably, these >90%-water DN gels exhibited dynamic impact stiffness (E*) values (similar to 1.1 and similar to 1.5 MPa) approaching swine meniscus (similar to 2.9 MPa). Dynamic impact energy-absorbing capability was much lower (median loss angles of similar to 2 degrees) than swine meniscus (>10 degrees), but it is intriguing that >90%-water materials can efficiently store energy. Also, fine 4/0 suture tear-out strength approached cartilage (similar to 2.1 and similar to 7.1 N v. similar to 13.5 N). Initial strength of attachment of DN gels to cartilage with acrylic tissue adhesive was also high (similar to 0.20 and similar to 0.15 N/mm(2)). Conclusions: DN gel strength and toughness properties stem from optimized entanglement of the 2 network components. DN gels thus have obvious structural parallels with cartilaginous tissues, and their surgical handling properties make them ideal candidates for clinical use.
  • Yong Mei Chen, Jian Ping Gong, Yoshihito Osada
    Macromolecular Engineering: Precise Synthesis, Materials Properties, Applications 4 2689 - 2717 2011/09/23 [Refereed][Not invited]
  • Ryusei Imabuchi, Yoshihiro Ohmiya, Hyuck Joon Kwon, Shin Onodera, Nobuto Kitamura, Takayuki Kurokawa, Jian Ping Gong, Kazunori Yasuda
    BMC MUSCULOSKELETAL DISORDERS 12 213  1471-2474 2011/09 [Refereed][Not invited]
     
    Background: We have recently found a phenomenon that spontaneous regeneration of a hyaline cartilage-like tissue can be induced in a large osteochondral defect by implanting a double-network (DN) hydrogel plug, which was composed of poly-(2-Acrylamido-2-methylpropanesulfonic acid) and poly-(N, N'-Dimetyl acrylamide), at the bottom of the defect. The purpose of this study was to clarify gene expression profile of the regenerated tissue in comparison with that of the normal articular cartilage. Methods: We created a cylindrical osteochondral defect in the rabbit femoral grooves. Then, we implanted the DN gel plug at the bottom of the defect. At 2 and 4 weeks after surgery, the regenerated tissue was analyzed using DNA microarray and immunohistochemical examinations. Results: The gene expression profiles of the regenerated tissues were macroscopically similar to the normal cartilage, but showed some minor differences. The expression degree of COL2A1, COL1A2, COL10A1, DCN, FMOD, SPARC, FLOD2, CHAD, CTGF, and COMP genes was greater in the regenerated tissue than in the normal cartilage. The top 30 genes that expressed 5 times or more in the regenerated tissue as compared with the normal cartilage included type-2 collagen, type-10 collagen, FN, vimentin, COMP, EF1alpha, TFCP2, and GAPDH genes. Conclusions: The tissue regenerated by using the DN gel was genetically similar but not completely identical to articular cartilage. The genetic data shown in this study are useful for future studies to identify specific genes involved in spontaneous cartilage regeneration.
  • Jian Fang Liu, Yong Mei Chen, Jing Jing Yang, Takayuki Kurokawa, Akira Kakugo, Kimiko Yamamoto, Jian Ping Gong
    TISSUE ENGINEERING PART A 17 (17-18) 2343 - 2357 1937-3341 2011/09 [Refereed][Not invited]
     
    Differentiation of embryoid bodies (EBs) into particular cell lineages has been extensively studied. There is an increasing interest in the effect of soft hydrogel scaffolds on the behavior of EBs, such as the initial adhesion, dynamic morphology change, and differentiation. In this study, without adding any other bioactive factors in the serum-containing medium, dynamic behaviors of mouse EBs loaded on the surface of hydrogels with different surface charge and chemical structures are investigated. EBs adhered quickly to negatively charged poly(sodium p-styrene sulfonate) (PNaSS) hydrogels, which facilitates EBs spreading, migration, and differentiation into three germ layers with high efficiency of cardiomyocytes differentiation, similar to that on gelatin coated polystyrene (PS) culture plate. While on neutral poly(acrylamide) (PAAm) hydrogels, EBs maintained the initial spherical morphology with high expression of pluripotency-related markers in the short culture periods, and then showed the significantly greater levels of selected endoderm markers after long-time culture. EBs cultured on negatively charged poly(2-acrylamido-2-methyl-propane sulfonic acid sodium salt) (PNaAMPS) gels demonstrated the analogous behaviors with that of neutral PAAm gels at early differentiation phase (day 4 + 1). Then, their adhesion, spreading and differentiation were quite similar to that on negatively charged PNaSS gels. The correlation between surface properties of hydrogels and EBs differentiation was discussed.
  • Tasuku Nakajima, Hidemitsu Furukawa, Yoshimi Tanaka, Takayuki Kurokawa, Jian Ping Gong
    JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 49 (17) 1246 - 1254 0887-6266 2011/09 [Refereed][Not invited]
     
    Introduction of soft filler in a hard body, which is one of the common toughening methods of hard polymeric materials, was applied for further toughening of robust double network (DN) hydrogels composed of poly(2-acrylamido-2-methylpropanesulfonic acid) gels (PAMPS gels) as the first component and polyacrylamide (PAAm) as the second component. The fracture energy of the DN gels with the void structure (called void-DN gels) became twice when the volume fraction of void was 1-3 vol % and the void diameter was much larger than the Flory radius of the PAAm chains. Such toughening was induced by wider range of internal fracture of the PAMPS network derived from partial stress concentration near void structure. Considering the mechanical tests and the dynamic light scattering results, it is implied that the absence of the load-bearing PAAm structure inside the void is important for the toughening. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1246-1254, 2011
  • ゲル-物性の研究と再生医療への応用
    黒川孝幸, 龔剣萍
    未来材料 11 (8) 2 - 4 2011/08 [Not refereed][Invited]
  • Kosuke Kamada, Hidemitsu Furukawa, Takayuki Kurokawa, Tomohiro Tada, Taiki Tominaga, Yukihiro Nakano, Jian Ping Gong
    JOURNAL OF PHYSICS-CONDENSED MATTER 23 (28) 284107  0953-8984 2011/07 [Refereed][Not invited]
     
    We studied the ability of surfactants to reduce friction by boundary lubrication for a bulk hydrogel sliding on a solid surface in an aqueous solution. A piece of negatively charged polyelectrolyte hydrogel was slid across solid surfaces with various levels of hydrophobicity, using a strain-controlled parallel-plate rheometer in water. A dramatic reduction in the sliding friction, especially in the low velocity region, was detected by the addition of a surfactant to the water medium. This friction reduction was only observed in gel-solid friction but not in solid-solid friction, indicating that the soft and wet nature of the gel surface was crucial for this surfactant-induced friction reduction. This phenomenon reveals that surfactants can remain at the gel-mated interface, thus preventing direct interfacial interaction between the sliding surfaces, and significantly decreasing the frictional stress. The reported dramatic reduction in friction highlights the frictional characteristics of soft and wet hydrogel materials.
  • Zi Liang Wu, Jian Ping Gong
    NPG ASIA MATERIALS 3 (4) 57 - 64 1884-4049 2011/06 [Refereed][Invited]
     
    Biological soft tissue and synthesized hydrogel both belong to the same 'soft and wet' class of substances, that is, they are both soft and contain water. However, whereas biological tissue such as muscles displays various forms of functionality, hydrogels generally have poor functionality, primarily due to the difference in structure biological tissue has a sophisticated structure whereas most hydrogels are amorphous. In recent years, biomacromolecules, block copolymers and liquid-crystalline molecules have been used to develop self-assembled architectures in synthetic physical or chemical hydrogels via intermolecular noncovalent interactions such as ionic bonding, hydrophobic interactions and hydrogen bonding. Ordered structures on various length scales endow the hydrogels with additional functions with promising applications in materials science, such as in tissue engineering and mechano-optical sensors. In this review, we briefly describe the recent developments in designing hydrogels with ordered structures of molecular assemblies and the resultant functionalities.
  • Nobuto Kitamura, Kazunori Yasuda, Munehiro Ogawa, Kazunobu Arakaki, Shuken Kai, Shin Onodera, Takayuki Kurokawa, Jian Ping Gong
    AMERICAN JOURNAL OF SPORTS MEDICINE 39 (6) 1160 - 1169 0363-5465 2011/06 [Not refereed][Invited]
     
    Background: A double-network (DN) gel, which was composed of poly-(2-acrylamido-2-methylpropanesulfonic acid) and poly(N, N'-dimetyl acrylamide) (PAMPS/PDMAAm), has the potential to induce chondrogenesis both in vitro and in vivo. Purpose: To establish the efficacy of a therapeutic strategy for an articular cartilage defect using a DN gel. Study Design: Controlled laboratory study. Methods: A 4.3-mm-diameter osteochondral defect was created in rabbit trochlea. A DN gel plug was implanted into the defect of the right knee so that a defect 2 mm in depth remained after surgery. An untreated defect of the left knee provided control data. The osteochondral defects created were examined by histological and immunohistochemical evaluations, surface assessment using confocal laser scanning microscopy, and real-time polymerase chain reaction (PCR) analysis at 4 and 12 weeks. Samples were quantitatively evaluated with 2 scoring systems reported by Wayne et al and O'Driscoll et al. Results: The DN gel-implanted defect was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type 2 collagen. Quantitative evaluation using the grading scales revealed a significantly higher score in the DN gel-implanted defects compared with the untreated control at each period (P<.0001). The mean relative values of type 2 collagen mRNAs in the regenerated tissue were obviously higher in the DN gel-implanted defect than in the untreated control at each period. The mean surface roughness of the untreated control was significantly higher than the normal cartilage at 12 weeks (P=.0106), while there was no statistical difference between the DN gel-implanted and normal knees. Conclusion: This study using the mature rabbit femoral trochlea osteochondral defect model demonstrated that DN gel implantation is an effective treatment to induce cartilage regeneration in vivo without any cultured cells or mammalian-derived scaffolds.
  • Zi Liang Wu, Daisuke Sawada, Takayuki Kurokawa, Akira Kakugo, Wei Yang, Hidemitsu Furukawa, Jian Ping Gong
    MACROMOLECULES 44 (9) 3542 - 3547 0024-9297 2011/05 [Refereed][Not invited]
     
    A robust, macroscopically anisotropic double-network (A-DN) hydrogel has been developed by combining the first anisotropic, physically cross-linked network of semirigid poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) and the second chemically cross-linked network of flexible polyacrylamide (PAAm) through double-network technology. Owing to the cooperative orientation of the self-assembled bundle structure of semirigid PBDTs, the A-DN gel shows a very sensitive and strong birefringence change upon deformation, which is always dominated by PBDT for the wide strain range investigated (epsilon = 0-18), regardless the fact that PAAm is in large excess. When the initial alignment of PBDT is vertical to the elongation direction, a birefringence reversion occurs at epsilon similar to 0.5, indicating that the initial vertical alignment of PBDT is overwhelmed by the strain-induced parallel alignment, even at such a small strain due to the cooperative reorientation of PBDT.
  • Zi Liang Wu, Takayuki Kurokawa, Daisuke Sawada, Jian Hu, Hidemitsu Furukawa, Jian Ping Gong
    MACROMOLECULES 44 (9) 3535 - 3541 0024-9297 2011/05 [Refereed][Not invited]
     
    We report a macroscopically anisotropic hydrogel developed by the facile dialysis of a synthetic semirigid polyanion in aqueous solution of multivalent cations. By the uniaxial diffusion of Ca2+ into two ends of a thin rectangular reaction cell containing semirigid polyanion poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) aqueous solution, centimeter-scale anisotropic hydrogels with the PBDT molecules and their self-assembled fibrous bundles align in perpendicular to the Ca2+ diffusion direction are obtained. The anisotropic gel shows a higher elastic modulus and tensile fracture stress/strain in the direction parallel to the PBDT orientation than that of perpendicular direction. By observing in situ the gelation process, an extraordinary molecular reorientation of PBDT at the Ca2+ diffusion flux front is observed for the first time. The mechanism for the molecular reorientation is discussed in terms of complexation and gelation.
  • Songmiao Liang, Zi Liang Wu, Jian Hu, Takayuki Kurokawa, Qiu Ming Yu, Jian Ping Gong
    MACROMOLECULES 44 (8) 3016 - 3020 0024-9297 2011/04 [Refereed][Not invited]
     
    Double-network (DN) hydrogels have attracted much attention in the soft matter community due to their excellent mechanical performance and unique fracture mechanism. On the basis of ultrathin film technique and optical microscope, we here report a method which is quite effective for accessing the fractured microstructure of DN hydrogels formed during the tensile and tearing process. During tensile deformation, fracture of the first network occurs even before yielding occurs. Concomitant with the yielding, wrinkle-like structure, which is due to the fracture of the first network, is clearly observed for the first time. This wrinkle-like structure disappears upon further deformation to strain-hardening region because of the further fracture of the first network. Similar microstructures are observed at the crack tip for samples experienced the tearing test. This work provides direct proofs for the assumption concerning the occurrence of local yielding and the formation of a huge damage zone at the crack tip during the crack propagation process of DN hydrogels.
  • Junji Saito, Hidemitsu Furukawa, Takayuki Kurokawa, Rikimaru Kuwabara, Shinya Kuroda, Jian Hu, Yoshimi Tanaka, Jian Ping Gong, Nobuto Kitamura, Kazunori Yasuda
    POLYMER CHEMISTRY 2 (3) 575 - 580 1759-9954 2011/03 [Refereed][Not invited]
     
    Robust bonding of a hydrogel in aqueous environment, either to another hydrogel or to a solid, is one of the major unsolved issues for the practical applications of hydrogels in various fields. Here we report robust bonding between a pair of hydrogel sheets, containing over 90 wt% of water, by applying the double-network (DN) structure. In the optimal condition, the peeling energy of the united gel sheets reaches 1200 J m(-2), which is comparable to the bulk fracture energy of a normal type of tough DN gels. This hydrogel bonding technique is also applied to form tough bonding between hydrogel and plastic plates. Furthermore, based on this technique, we have developed a facile method to synthesize robust double network hydrogels with any desirable free-shape from micro-gel precursors. These novel techniques will substantially merit the applications of the tough hydrogels in various fields, such as an artificial meniscus.
  • Kazunobu Arakaki, Nobuto Kitamura, Takayuki Kurokawa, Shin Onodera, Fuminori Kanaya, Jian-Ping Gong, Kazunori Yasuda
    JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE 22 (2) 417 - 425 0957-4530 2011/02 [Refereed][Not invited]
     
    We have recently discovered that spontaneous hyaline cartilage regeneration can be induced in an osteochondral defect in the rabbit, when we implant a novel double-network (DN) gel plug at the bottom of the defect. To clarify whether joint immobilization inhibits the spontaneous hyaline cartilage regeneration, we conducted this study with 20 rabbits. At 4 or 12 weeks after surgery, the defect in the mobile knees was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type-2 collagen, while no cartilage tissues were observed in the defect in the immobilized knees. Type-2 collagen, Aggrecan, and SOX9 mRNAs were expressed only in the mobile knees at each period. This study demonstrated that joint immobilization significantly inhibits the spontaneous hyaline cartilage regeneration induced by the DN gel implantation. This fact suggested that the mechanical environment is one of the significant factors to induce this phenomenon.
  • Masashi Yokota, Kazunori Yasuda, Nobuto Kitamura, Kazunobu Arakaki, Shin Onodera, Takayuki Kurokawa, Jian-Ping Gong
    BMC MUSCULOSKELETAL DISORDERS 12 (-) 49 - - 1471-2474 2011/02 [Refereed][Not invited]
     
    Background: Functional repair of articular osteochondral defects remains a major challenge not only in the field of knee surgery but also in tissue regeneration medicine. The purpose is to clarify whether the spontaneous hyaline cartilage regeneration can be induced in a large osteochondral defect created in the femoral condyle by means of implanting a novel double-network (DN) gel at the bottom of the defect. Methods: Twenty-five mature rabbits were used in this study. In the bilateral knees of each animal, we created an osteochondral defect having a diameter of 2.4-mm in the medial condyle. Then, in 21 rabbits, we implanted a DN gel plug into a right knee defect so that a vacant space of 1.5-mm depth (in Group I), 2.5-mm depth (in Group II), or 3.5-mm depth (in Group III) was left. In the left knee, we did not apply any treatment to the defect to obtain the control data. All the rabbits were sacrificed at 4 weeks, and the gross and histological evaluations were performed. The remaining 4 rabbits underwent the same treatment as used in Group II, and real-time PCR analysis was performed at 4 weeks. Results: The defect in Group II was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type-2 collagen. The Wayne's gross appearance and histology scores showed that Group II was significantly greater than Group I, III, and Control (p < 0.012). The relative expression level of type-2 collagen, aggrecan, and SOX9 mRNAs was significantly greater in Group II than in the control group (p < 0.023). Conclusions: This study demonstrated that spontaneous hyaline cartilage regeneration can be induced in vivo in an osteochondral defect created in the femoral condyle by means of implanting the DN gel plug at the bottom of the defect so that an approximately 2-mm deep vacant space was intentionally left in the defect. This fact has prompted us to propose an innovative strategy without cell culture to repair osteochondral lesions in the femoral condyle.
  • Yong-mei Chen, Jing-jing Yang, Yoshihito Osada, Jian Ping Gong
    CHINESE JOURNAL OF POLYMER SCIENCE 29 (1) 23 - 41 0256-7679 2011/01 [Refereed][Invited]
     
    Synthetic hydrogels can be used as scaffolds that not only favor endothelial cells (ECs) proliferation but also manipulate the behaviors and functions of the ECs. In this review paper, the effect of chemical structure, Young's modulus (E) and zeta potential (zeta) of synthetic hydrogel scaffolds on static cell behaviors, including cell morphology, proliferation, cytoskeleton structure and focal adhesion, and on dynamic cell behaviors, including migration velocity and morphology oscillation, as well as on EC function such as anti-platelet adhesion, are reported. It was found that negatively charged hydrogels, poly(2-acrylamido-2-methylpropanesulfonic sodium) (PNaAMPS) and poly(sodium p-styrene sulphonate) (PNaSS), can directly promote cell proliferation, with no need of surface modification by any cell-adhesive proteins or peptides at the environment of serum-containing medium. In addition, the Young's modulus (E) and zeta potential (zeta) of hydrogel scaffolds are quantitatively tuned by copolymer hydrogels, poly(NaAMPS-co-DMAAm) and poly(NaSS-co-DMAAm), in which the two kinds of negatively charged monomers NaAMPS and NaSS are copolymerized with neutral monomer, N,N-dimethylacrylamide (DMAAm). It was found that the critical zeta potential of hydrogels manipulating EC morphology, proliferation, and motility is zeta (critical) = -20.83 mV and zeta (critical) = -14.0 mV for poly(NaAMPS-co-DMAAm) and poly(NaSS-co-DMAAm), respectively. The above mentioned EC behaviors well correlate with the adsorption of fibronectin, a kind of cell-adhesive protein, on the hydrogel surfaces. Furthermore, adhered platelets on the EC monolayers cultured on the hydrogel scaffolds obviously decreases with an increase of the Young's modulus (E) of the hydrogels, especially when E > 60 kPa. Glycocalyx assay and gene expression of ECs demonstrate that the anti-platelet adhesion well correlates with the EC-specific glycocalyx. The above investigation suggests that understanding the relationship between physic-chemical properties of synthetic hydrogels and cell responses is essential to design optimal soft and wet scaffolds for tissue engineering.
  • Nafees Ahmed, Takayuki Murosaki, Akira Kakugo, Takayuki Kurokawa, Jian Ping Gong, Yasuyuki Nogata
    SOFT MATTER 7 (16) 7281 - 7290 1744-683X 2011 [Refereed][Not invited]
     
    In this paper, settlement, metamorphosis, and long term growth of barnacles on soft substrates with a wide elasticity range (modulus 0.01-0.47 MPa) as well as with the variation in wettability were investigated for the first time in vitro, in the laboratory environment. Tough double-network (DN) hydrogels and polydimethylsiloxane (PDMS) were used as the soft hydrophilic substrates and hydrophobic substrates, respectively, and polystyrene (PS), a hard and hydrophobic substrate, was used as a control. It was observed that (1) the initial settlement and metamorphosis of cyprid larvae dramatically increase with the substrate elastic modulus while not showing an explicit dependence on the substrate wettability; (2) the growth rate of barnacles on both DN gels and PDMSs does not show an explicit dependence on the elasticity of the soft substrates, while it shows a slightly higher value on the hydrophobic PDMSs than on the hydrophilic DN gels; (3) the growth rate on these soft substrates is explicitly lower than that on the rigid PS substrate at the late stage of the growth; (4) the "self-release'' phenomenon of barnacles was observed for the PDMS substrate with a modulus higher than 0.01 MPa. Based on these observations, the antifouling effects of the soft substrates on barnacles were discussed.
  • Yoshiki Tamura, Ryuzo Kawamura, Kazuhiro Shikinaka, Akira Kakugo, Yoshihito Osada, Jian Ping Gong, Hiroyuki Mayama
    SOFT MATTER 7 (12) 5654 - 5659 1744-683X 2011 [Refereed][Not invited]
     
    In this study, we show that the energy-dissipative active self-assembly of microtubules (MTs) via a kinesin-based motility system produces various MT assemblies such as bundle-, network-, and ring-shaped structures depending on the initial conditions. Structural polymorphism of the MT assembly is depicted through phase diagrams, and morphogenesis of the MT assembly is discussed based on the following factors: binding force between MTs and motility-driving force from kinesins. This study provides new insights into the energy-dissipative dynamic self-organization of biological systems.
  • Zi Liang Wu, Md Arifuzzaman, Takayuki Kurokawa, Hidemitsu Furukawa, Jian Ping Gong
    SOFT MATTER 7 (5) 1884 - 1889 1744-683X 2011 [Refereed][Not invited]
     
    We report a novel giant oriented structure observed in plate hydrogels synthesized by photo-polymerization of cationic monomers with a cross-linker in the presence of a semi-rigid polyanion as the dopant. The giant structure, formed via self-assembly of the semi-rigid polyion complex, consists of millimetre-scale cubic packed concentric cylindrical domains that are sandwiched by two homeotropically aligned outer layers. A universal relationship between the diameter of the cylinders D and the thickness of the swollen gel T is observed, as D = 0.5T, regardless the change in the concentrations of the polyanion and precursor cationic monomer. This result permits us to induce the giant concentric structure into hydrogels with tunable cylindrical sizes.
  • Md. Anamul Haque, Gen Kamita, Takayuki Kurokawa, Kaoru Tsujii, Jian Ping Gong
    ADVANCED MATERIALS 22 (45) 5110 - + 0935-9648 2010/12 [Refereed][Not invited]
     
    A novel anisotropic hydrogel, consisting of lamellar bilayers and a polymer network, with unidirectional alignment of the bilayer structure has been synthesized. The unidirectional orientation of bilayer in the gels leads to one-dimensional swelling, strong anisotropy in elastic modulus, and exhibits excellent visible color. The gel shows reversibly tunable structural color under mechanical stimulation and could be the basis for a deformation-based color display.
  • 海藻にフジツボが付着しないのはなぜか−海藻に学ぶ抗生物付着ゲルの開発−
    室﨑喬之, 龔剣萍
    BIOINDUSTRY 27 (12) 63 - 71 2010/11 [Not refereed][Invited]
  • Yong Mei Chen, Takayuki Kurokawa, Taiki Tominaga, Kazunori Yasuda, Yoshihito Osada, Jian Ping Gong, Kimiko Yamamoto, Joji Ando
    ADVANCED ENGINEERING MATERIALS 12 (11) B628 - B636 1438-1656 2010/11 [Refereed][Not invited]
     
    We investigate the sliding friction of HUVEC monolayers cultured on PNaSS gel, intending to elucidate the role of glycocalyx on the surface of ECs in friction reduction. Three sets of HUVEC monolayers are investigated: an as-cultured HUVEC monolayer; a HUVEC monolayer treated with TGF-beta(1), which increases the glycocalyx by 148%; and a HUVEC monolayer treated with heparinase I, which reduces the glycocalyx by 57%. When being slid on a flat, glass surface, the frictional stress of the HUVEC monolayer decreases in the order: heparinase-I-treated> as-cultured> TGF-beta(1)-treated samples. The results suggest that glycocalyx may play a role in reducing the friction of endothelial cell monolayer.
  • Hiroko Itagaki, Takayuki Kurokawa, Hidemitsu Furukawa, Tasuku Nakajima, Yukiteru Katsumoto, Jian Ping Gong
    MACROMOLECULES 43 (22) 9495 - 9500 0024-9297 2010/11 [Refereed][Not invited]
     
    In the previous studies, we have developed double network hydrogels (DN gels) with extra ordinarily high mechanical strength and toughness although the gels contain 90 wt % of water In this study we investigated the effect of water content on the mechanical behavior of the DN gel consists of poly(2 acrylamido 2 methylpropanesulfonic acid) gels (PAMPS gels) as the first network and polyacrylamide gels (PAAm gels) as the second network When the DN gel was dried gradually from its equilibrium swelling state (90 wt % water content) it exhibited a ductile behavior with a very high fracture stress and strain at an intermediate water content c (65 wt % < c < 75%) and then became brittle upon further decreasing in water content (c < 60 wt %) The behavior of the DN gel was compared with the corresponding single network gels, PAMPS and PAAm It is found that at the intermediate water content the fracture stress and strain of PAAm gel reached maximum, and the brittle ductile change of DN gel upon with the change in water content was the results of the change in the mechanical properties of PAAm network
  • Jing Jing Yang, Yong Mei Chen, Takayuki Kurokawa, Jian Ping Gong, Shin Onodera, Kazunori Yasuda
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 95A (2) 531 - 542 1549-3296 2010/11 [Refereed][Not invited]
     
    We measured the gene expression, glycocalyx content, and surface properties of human coronary artery endothelial cells (HCAECs) cultured on poly(sodium p-styrene sulfonate) (PNaSS) hydrogels with various levels of elasticity ranged in 3-300 kPa. We found that all HCAECs reached confluence on these hydrogels while retaining the similar expression of EC-specific markers to that on polystyrene (PS), a widely used scaffold in cell culture in vitro. Real-time polymerase chain reaction (PCR) and glycosaminoglycan (GAG) assay showed that the amount of EC-specific glycocalyx secreted by HCAECs cultured on PNaSS gels was higher than that cultured on PS, and it increased with an increase of gel elasticity. Furthermore, the HCAECs cultured on PNaSS gels showed excellent property against platelet adhesion and lower surface friction than that on PS. The platelet adhesion and surface friction of HCAECs cultured on PNaSS gels also depend on the elasticity of gels. The largest amount of EC-specific glycocalyx, excellent blood compatibility, and the lowest friction were observed when the elastic modulus of the gel was larger than 60 kPa. Overall, HCAECs cultured on these hydrogels have better properties than those cultured on PS scaffold, demonstrating the PNaSS gels can be used as potential tissue engineering material for blood vessels. (C) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 95A: 531542, 2010.
  • Zi Liang Wu, Takayuki Kurokawa, Songmiao Liang, Jian Ping Gong
    MACROMOLECULES 43 (19) 8202 - 8208 0024-9297 2010/10 [Refereed][Not invited]
     
    In this Article, we report a systematic research on a hydrogel with dual networks or 10(4) times difference in mesh sizes. The structure was developed by polymerizing a cationic monomer N-[3-(N.N-dimethylamino)propyl] acrylamide methyl chloride quarternary (DMAPAA-Q) in the presence of a small amount of semirigid polyanion, poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT). During the polymerization, polyion complexes were formed, which caused viscoelastic phase separation (VPS) due to the self-assembly of the semirigid polyion complexes, whereupon the dynamic coupling or phase separation and gelation is crucial for the structure formation. When PBDT was above its overlap concentration (C(PBDT) > C*), a critical concentration of cationic monomer, C(Q) approximate to 1.5 M, was observed, below which VPS occurred and turbid hydrogels with the dual network structure were formed, whereas above which, a transparent, anisotropic hydrogel was formed. It has been elucidated that the critical effect of C(Q) on the VPS process is through the ionic strength mechanism. That is, the abundant unreacted cationic monomer at high C(Q) behaves as a simple salt that screens the electrostatic interaction between the polycation and PBDT and therefore suppresses the occurrence of the phase separation. Furthermore, we investigated the effects of reaction kinetics on the VPS and the microstructure of gels by changing the concentrations of photoinitiator and chemical cross-linker. The dual network gels possess controllable turbidity degrees and mesh sizes corresponding to different quench depths of the phase separation. On the basis of these results, as well as in situ observation of the structure formation during the polymerization, we proposed a detailed mechanism for the formation or dual networks and the anisotropic hydrogels.
  • Jing Jing Yang, Yong Mei Chen, Jian Fang Liu, Takayuki Kurokawa, Jian Ping Gong
    TISSUE ENGINEERING PART A 16 (8) 2529 - 2540 1937-3341 2010/08 [Refereed][Not invited]
     
    Chondrocytes rapidly dedifferentiate into a more fibroblastic phenotype on a two-dimensional polystyrene substratum. This impedes fundamental research on these cells as well as their clinical application. This study investigated the redifferentiation behavior of dedifferentiated chondrocytes on a hydrogel substratum. Dedifferentiated normal human articular chondrocyte-knee (NHAC-kn) cells were released from the sixth-passage monolayer cultured on a polystyrene surface. These cells were then subcultured on a chemically crosslinked copolymer hydrogel, that is, poly(NaAMPS-co-DMAAm), and the cells thus obtained were used as the seventh-passage cultivation. Copolymer gels were synthesized from a negatively charged monomer, the sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid (NaAMPS), and a neutral monomer, N,N-dimethylacrylamide (DMAAm). These gels were of different compositions because the molar fraction (F) of NaAMPS was varied (F = 0, 0.2, 0.4, 0.6, 0.8, and 1.0). The dedifferentiated NHAC-kn cells spontaneously redifferentiated to normal NHAC-kn cells on neutral (F = 0) and poly(NaAMPS-co-DMAAm) hydrogels of low charge density (F = 0.2). This was deduced from the cell morphology and expression of cartilage-specific genes and proteins. These results should enable us to establish a simple and efficient method for preparing large amounts of chondrocytes by cultivation on the surfaces of neutral and low-charge-density hydrogels.
  • 高強度ダブルネットワークゲル
    黒川孝幸, 龔剣萍
    化学工学会誌 74 (7) 338 - 340 2010/07 [Not refereed][Invited]
  • Zi Liang Wu, Takayuki Kurokawa, Songmiao Liang, Hidemitsu Furukawa, Jian Ping Gong
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 132 (29) 10064 - 10069 0002-7863 2010/07 [Refereed][Not invited]
     
    A hydrogel with cylindrically symmetric structure at macroscopic scale has been developed by polymerization of a cationic monomer in the presence of a small amount of semi-rigid polyanion poly(2,2'-disulfony1-4,4'-benzidine terephthalamide) (PBDT) in a cylinder glass tube. The polyion complex radially aligns in the outer region of the synthesized cylinder gel. On the other hand, it orients in concentric and axial directions in the inner region. To the authors' knowledge, this is the first report of such millimeter-scale ordered structure developed in a polymeric hydrogel. We elucidate that homeotropic alignment on the glass wall is energetically favorable for the semi-rigid polyion complex, resulting in the radial orientation in the outer region. In the inner region, the oriented structures result from the monomer diffusion (due to the heterogeneous polymerization) that induces PBDT orientation perpendicular to the diffusion direction. The structured gels showing sensitive response of birefringence to external force are expected to find applications in optical sensors.
  • Tasuku Nakajima, Naoyuki Takedomi, Takayuki Kurokawa, Hidemitsu Furukawa, Jian Ping Gong
    POLYMER CHEMISTRY 1 (5) 693 - 697 1759-9954 2010/07 [Refereed][Invited]
     
    The creation of double network hydrogels (DN gels), which show extremely high mechanical strength, enable hydrogels to be applied both in medical and industrial fields. However, one obstacle for various applications is the lack of formability of DN gels, owing to the brittleness of the first network PAMPS gels. In order to overcome this problem, we synthesized free-shaped DN gels (called PVA-DN gels) by using a physically cross-linked PVA gel as an "internal mold". PVA-DN gels can form any complex shapes and their mechanical properties were comparable to those of conventional DN gels. This study may expand the application of tough hydrogels.
  • Kazunobu Arakaki, Nobuto Kitamura, Hiroyuki Fujiki, Takayuki Kurokawa, Mikio Iwamoto, Masaru Ueno, Fuminori Kanaya, Yoshihito Osada, Jian Ping Gong, Kazunori Yasuda
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 93A (3) 1160 - 1168 1549-3296 2010/06 [Refereed][Not invited]
     
    This study evaluated the in vivo influence of a poly-(2-Acrylamido-2-methylpropane sulfonic acid)/poly(N,N'-dimetyl acrylamide) (PAMPS/PDMAAm) double-network (DN) hydrogel on counterface cartilage in rabbit knee joints and its ex vivo friction properties on normal cartilage. In the first experiment, the DN gel was implanted in a surgically created defect in the femoral trochlea of rabbit knee joints and the left knee was used as the control. Evaluations using a confocal laser scanning microscopy demonstrated that the DN gel did not affect the surface microstructure (surface roughness, the number of small pits) of the counterface cartilage in viva at 4 and 12 weeks. The histology also showed that the DN gel had no pathological damage on the cartilage matrices and cells at 4 weeks. However, two of the five DN gel-implanted knees showed mild irregularity on the counterface cartilage surface at 12 weeks. In the second experiment, the friction property between the normal and the artificial cartilage was determined using a joint simulator apparatus. The ex vivo mean friction coefficient of the DN gel to normal cartilage was 0.029, while that of the normal-to-normal cartilage articulation was 0.188. The coefficient of the DN gel-to-normal cartilage articulation was significantly lower than that of the normal-to-normal cartilage articulation (p < 0.0001). This study suggested that the PAMPS/PDMAAm DN gel has very low friction coefficient on normal cartilage and has no significant detrimental effects on counterface cartilage in vivo, and can be a promising material to develop the artificial cartilage. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res 93A: 1160-1168, 2010
  • Ryuzo Kawamura, Akira Kakugo, Yoshihito Osada, Jian Ping Gong
    NANOTECHNOLOGY 21 (14) 145603  0957-4484 2010/04 [Refereed][Not invited]
     
    Recently, a method was established for the formation of microtubule (MT) assemblies by an active self-organization (AcSO) process, in which MTs were crosslinked during sliding motion on a kinesin-coated surface, and this was coupled with adenosine triphosphate (ATP) hydrolysis. Streptavidin (ST) was the glue used to crosslink biotin-labeled MTs. Although most of the MT assemblies were in the bundle form, they varied in size, shape and motility, depending on the initial conditions used. In this paper, we systematically examined the effects of the concentrations of kinesin, ST and MT on the formation of MT bundles under the initial conditions of the process.
  • Takayuki Kurokawa, Hidemitsu Furukawa, Wei Wang, Yoshimi Tanaka, Jian Ping Gong
    ACTA BIOMATERIALIA 6 (4) 1353 - 1359 1742-7061 2010/04 [Refereed][Not invited]
     
    A method for binding a tough double-network (ON) hydrogel and a porous solid utilizing the double-network principle is proposed. The effects of the pore size of the solid and the structure of the DN gel in the pores on bonding strength were investigated by a peeling test. Porous solids with pore sizes of the order of several microns afforded strong gel-substrate interfaces. Under optimal conditions a bonding strength as high as similar to 1000 N m(-1) was reached. The results obtained were compared with the strength of the bulk DN gel, and discussed in terms of the double-network principle at the bonding interface. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • 超高強度ダブルネットワークゲルの創製とその高強度化メカニズム
    中島 祐, 龔 剣萍
    物性研究 93 (5) 551 - 557 2010/02 [Not refereed][Invited]
  • Yui Hagiwara, Ananda Putra, Akira Kakugo, Hidemitsu Furukawa, Jian Ping Gong
    CELLULOSE 17 (1) 93 - 101 0969-0239 2010/02 [Refereed][Invited]
     
    Using the double-network (DN) method, bacterial cellulose/polyacrylamide (BC/PAAm) DN gels able to sustain not only high elongation but also high compression have been synthesized by combining BC gel as the first network with PAAm as the second network in the presence of N,N'-methylene bisacrylamide (MBAA) as a cross-linker. This DN gel was obtained by modifying the monomer concentration of the second network, acrylamide monomer (AAm) and MBAA, and by controlling the water content of the first network, BC gel. The mechanical properties are discussed in term of the swelling degree (q), which is independent of the concentration of AAm and MBAA. It was found that, for BC/PAAm DN gels with the first network formed from BC gel with high q (BC(q=120)), the tensile and compressive modulus (E) scales with q as E proportional to q(-2). The tensile fracture stress, sigma(F), of this DN gel was almost independent of q, that is sigma(F) proportional to q(0); but the compressive fracture stress, sigma(F), scaled with q as E proportional to q(-2). Meanwhile, the tensile and compressive fracture strain (epsilon(F)) of the gel is almost independent of q, which is caused by AAm concentration change, but linearly increased with q, which is caused by MBAA concentration change. Furthermore, by decreasing the water content of the BC gel prior to polymerization of the second (PAAm) network, a ligament-like tough BC/PAAm DN gel could be obtained with tensile strength of 40 MPa.
  • Jian Ping Gong
    SOFT MATTER 6 (12) 2583 - 2590 1744-683X 2010 [Refereed][Invited]
     
    Double-network (DN) gels have drawn much attention as an innovative material having both high water content (ca. 90 wt%) and high mechanical strength and toughness. DN gels are characterized by a special network structure consisting of two types of polymer components with opposite physical natures: the minor component is abundantly cross-linked polyelectrolytes (rigid skeleton) and the major component comprises of poorly cross-linked neutral polymers (ductile substance). The former and the latter components are referred to as the first network and the second network, respectively, since the synthesis should be done in this order to realize high mechanical strength. For DN gels synthesized under suitable conditions (choice of polymers, feed compositions, atmosphere for reaction, etc.), they possess hardness (elastic modulus of 0.1-1.0 MPa), strength (failure tensile nominal stress 1-10 MPa, strain 1000-2000%; failure compressive nominal stress 20-60 MPa, strain 90-95%), and toughness (tearing fracture energy of 100 similar to 1000 J m(-2)). These excellent mechanical performances are comparable to that of rubbers and soft load-bearing bio-tissues. The mechanical behaviors of DN gels are inconsistent with general mechanisms that enhance the toughness of soft polymeric materials. Thus, DN gels present an interesting and challenging problem in polymer mechanics. Extensive experimental and theoretical studies have shown that the toughening of DN gel is based on a local yielding mechanism, which has some common features with other brittle and ductile nano-composite materials, such as bones and dentins.
  • Tasuku Nakajima, Hidemitsu Furukawa, Jian Ping Gong, Eric K. Lin, Wen-li Wu
    POLYMER NETWORKS: SYNTHESIS, PROPERTIES, THEORY AND APPLICATIONS 291-292 122 - + 1022-1360 2010 [Refereed][Invited]
     
    The long-standing pursuit of a synthetic equivalent to tissue cartilage has sprouted significant new activities in strategies for new material synthesis, among them a noticeable one being the double-network hydrogels (DN-gels) scheme. DN-gels were prepared from the combination of an anionic polyelectrolyte network and a lightly crosslinked neutral polymer. These hydrogels exhibit an intriguing combination of properties intrinsic to natural cartilage: a low surface friction coefficient and a fracture toughness much higher than either of the constituent materials. The reinforcement of a hard, brittle polymer gel with a soft, viscoelastic neutral polymer is counter-intuitive. Based on our recent results from neutron scattering measurements, we proposed a deformation mechanism where the molecular association between these two polymers plays a pivotal role. In this work, we further evaluate the proposed mechanism by performing mechanical measurements on DN-gel samples with different polyelectrolyte network structure. The experimental results provide qualitative support for the proposed deformation mechanism.
  • Tomomi Masui, Satoshi Koizumi, Takeji Hashimoto, Kazuhiro Shikinaka, Akira Kakugo, Jian Ping Gong
    SOFT MATTER 6 (9) 2021 - 2030 1744-683X 2010 [Refereed][Not invited]
     
    By employing a combined method of ultra-small-angle & small-angle neutron scattering (USANS&SANS) and fluorescence microscopy (FM), we investigated the solution mixtures of filamentous actin (F-actin) and the synthesized cationic polymer poly-N-[3-(dimethylamino) propyl] acrylamide methylchloride quaternary (PDMAPAA-Q). The combined USANS&SANS method, covering a wide range of length scales from 10 micrometres to nanometres, plays a crucial role in elucidating the hierarchical structure of the complex structure, as it is in an aqueous solution. FM determined that the complex of F-actin and PDMAPAA-Q appears with a finite size (> 10 mu m), referred to as a superbundle, and its morphology changes from a globular one to a stretched one by increasing the salt (KCl) concentration C(s) from 0.01 to 0.3 M. USANS& SANS revealed that the superbundle is composed of a structural unit of a protobundle, in which PDMAPAA-Q binds F-actins in order to form a hexagonal lattice. The diameter of the protobundle (D(II)), determined by USANS& SANS, increases from 40 to 290 nm as C(s) increases from 0.01 to 0.3 M. In order to explain the finite-size & hierarchical condensation observed in the actin/PDMAPAA-Q solution, we employ a scenario of imperfect charge neutralization between F-actins and PDMAPAA-Q. Due to the chain connectivity of PDMAPAA-Q, a spatial distribution of positive charges around the F-actins becomes inhomogeneous, so that the repulsive electrostatic interaction appearing in the protobundle limits bundle formation with an infinite-size. The morphology of the superbundles is controlled by the bending rigidity due to individual protobundles, which significantly increases as D(II) increases.
  • Youichi Tsuchiya, Tomotaka Komori, Minako Hirano, Tomohiro Shiraki, Akira Kakugo, Toru Ide, Jian-Ping Gong, Sunao Yamada, Toshio Yanagida, Seiji Shinkai
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 49 (4) 724 - 727 1433-7851 2010 [Refereed][Not invited]
  • Ryuzo Kawamura, Akira Kakugo, Yoshihito Osada, Jian Ping Gong
    LANGMUIR 26 (1) 533 - 537 0743-7463 2010/01 [Refereed][Not invited]
     
    By using rigid microtubules (MTs) prepared by polymerization with guanylyl-(alpha, beta)-methylene-diphosphonate GMPCPP, giant straight-shaped MT bundles were selectively obtained through a dynamic self-assembly process. We demonstrate the effect of the rigidity oil the shape and motility of MT bundle composed of GMPCPP-polymerized MTs (GMPCPP-MTs) compared with control MTs that were polymerized with GTP and stabilized with paclitaxel.
  • Jian Ping Gong, Yoshihito Osada
    HIGH SOLID DISPERSIONS 236 203 - 246 0065-3195 2010 [Refereed][Not invited]
     
    This chapter describes recent progress in the study and development of hydrogels with tough mechanical strength, low frictional coefficient, and wear-resisting properties. Furthermore, examples of application of gels as cell scaffolds and substitutes of biological tissues, such as artificial articular cartilage, will be introduced.
  • Akira Kakugo, Yoshiki Tamura, Kazuhiro Shikinaka, Momoko Yoshida, Ryuzo Kawamura, Hidemitsu Furukawa, Yoshihito Osada, Jian Ping Gong
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 (50) 18089 - 18095 0002-7863 2009/12 [Refereed][Not invited]
     
    Tubulin polymerization in a confined space under a temperature gradient produced well-oriented microtubule assemblies with preferential polarity. We analyzed the structure and polarity of these assemblies at various levels of resolution by performing polarized light microscopy (millimeter order), fluorescence microscopy (micrometer order), and transmission electron microscopy (nanometer order).
  • Zi Liang Wu, Hidemitsu Furukawa, Wei Yang, Jian Ping Gong
    ADVANCED MATERIALS 21 (46) 4696 - + 0935-9648 2009/12 [Refereed][Not invited]
     
    A dual network gel, consisting of a micrometer-scaled network-like structure of a semirigid polyion complex nested in a nanometer-scaled polycationic network, has been developed by polymerization of a cationic monomer in the presence of a small amount of semi-rigid polyanion as dopant. Self-assembly and viscoelastic phase separation (see figure) compete with each other during the polymerization and render the micrometer-scaled network structure, which is permanently frozen by the subsequent gelation.
  • Kazuhiro Shikinaka, Shintaro Takaoka, Akira Kakugo, Yoshihito Osada, Jian Ping Gong
    JOURNAL OF APPLIED POLYMER SCIENCE 114 (4) 2087 - 2092 0021-8995 2009/11 [Refereed][Not invited]
     
    Fibrous actomyosin gel was obtained by applying an external shear stress to actomyosin solution injected from a syringe and then performing chemical cross-linking. The actomyosin gel shrunk when ATP was added, and the shrinkage ratio was proportional to its ATPase activity. The shrinkage of the gel was repeatable at least for four times. Furthermore, the shrinkage of the gel enhanced the regular orientation of the actin and myosin filaments in the gel, which in turn enhanced the shrinking velocity of the gel. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 2087-2092, 2009
  • FUJIKI Hiroyuki, DAIMARUYA Masashi, KITAMURA Nobuto, KONDO Eiji, YASUDA Kazunori, CHEN Yong Mei, GONG Jian Ping, OSADA Yoshihito
    Japanese journal of clinical biomechanics 日本臨床バイオメカニクス学会 30 (0) 63 - 70 1884-5274 2009/09/20 [Not refereed][Not invited]
  • Hyuck Joon Kwon, Kazunori Yasuda, Yoshihiro Ohmiya, Ken-ichi Honma, Yong Mei Chen, Jian Ping Gong
    Acta Biomaterialia 6 (2) 319 - 714 2009/08 [Refereed][Not invited]
  • Masakazu Takata, Tetsuo Yamaguchi, Jian Ping Gong, Masao Doi
    Journal of the Physical Society of Japan 78 (8) 084602-1 - 081602-5 0031-9015 2009/08 [Refereed][Not invited]
     
    Sliding friction of a charged gel on a substrate was investigated by applying electric voltage between gel and the substrate. It is found that the sliding friction increases markedly with the increase of the applied voltage; the friction coefficient increased by a factor of about 10 when 70 V voltage is applied. This voltage dependence of frictional force is explained by using the adhesion friction model proposed by Schallamach. © 2009 The Physical Society of Japan.
  • Yoshimi Tanaka, Hiroyuki Abe, Takayuki Kurokawa, Hidemitsu Furukawa, Jian Ping Gong
    MACROMOLECULES 42 (15) 5425 - 5426 0024-9297 2009/08 [Refereed][Not invited]
  • Yoshihito Osada, Jian Ping Gong
    POLYMER SCIENCE SERIES A 51 (6) 689 - 700 0965-545X 2009/06 [Not refereed][Invited]
     
    We introduce here an ATP (adenosine triphosphate)-fueled nano-biomachine constructed from actin and myosin gels. Various types of chemically cross-linked actin gel, which are tens of times larger in size than native actin filaments (F-actin), were formed by complexing with cation-polymers and placed on a chemically cross-linked myosin gel. By adding dilute solution of ATP, they moved along the myosin gel with a velocity as high as that of native F-actin by coupling to ATP hydrolysis. Formation mechanism and structure of actin complexes as well as those of myosin gels were studied in detail and elucidated with the specific characteristics of the motility. These results demonstrate that one can construct nano-biomachines fueled by chemical energy of ATP with controlled motility.
  • Qiu Ming Yu, Yoshimi Tanaka, Hidemitsu Furukawa, Takayuki Kurokawa, Jian Ping Gong
    MACROMOLECULES 42 (12) 3852 - 3855 0024-9297 2009/06 [Refereed][Not invited]
  • 高強度DNゲルの開発と関節軟骨再生誘導への応用
    中島 祐, 龔 剣萍, 安田和則
    工業材料 57 (6) 38 - 41 2009/05 [Not refereed][Invited]
  • 生命科学時代の新材料−高弾性・高靭性DNゲル
    龔剣萍
    高分子 58 (5) 327 - 331 2009/05 [Not refereed][Invited]
  • Manami Misu, Hidemitsu Furukawa, Hyuck-Joon Kwon, Kazuhiro Shikinaka, Akira Kakugo, Toshifumi Satoh, Yoshihito Osada, Jian Ping Gong
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 89A (2) 424 - 431 1549-3296 2009/05 [Refereed][Not invited]
     
    We developed a novel in situ method for the control of F-actin assembly by using a synthetic photoresponsive polycation. The photoresponsive polycation mainly comprises a water-soluble cationic monomer and also contains a small amount of the monomer of a triphenylmethane leucohydroxide derivative (20 mol %), which is a well-known photochromic molecule that can be cationized in aqueous solution by ultra violet (UV) irradiation, thereby causing an increase in the total charge on the photoresponsive polycation. Thus, by exposure to UV radiation in aqueous solution, F-actin and the photoresponsive polycation start assembling into F-actin/photoresponsive polycation complexes of various morphologies Such as bundles, coils, and networks, depending upon the concentrations of both the F-actin and salt. Further, localized UV irradiation can be applied in order to control the local formation of F-actin/photoresponsive polycation complexes. Thus, this technique provides a novel method for the spatiotemporal control of F-actin assembly and can be applied to investigate the unknown characteristics of F-actin. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 89A: 424-431, 2009
  • Kazunori Yasuda, Nobuto Kitamura, Jian Ping Gong, Kazunobu Arakaki, Hyuck Joon Kwon, Shin Onodera, Yong Mei Chen, Takayuki Kurokawa, Fuminori Kanaya, Yoshihiro Ohmiya, Yoshihito Osada
    MACROMOLECULAR BIOSCIENCE 9 (4) 307 - 316 1616-5187 2009/04 [Refereed][Not invited]
     
    We have developed a novel method to induce spontaneous hyaline cartilage regeneration in vivo for a large osteochondral defect by implanting a plug made from a double-network hydrogel composed of poly(2-acrylamido-2-methylpropanesulfonic acid) and poly(N,N'-dimethylacrylamide) at the bottom of the defect, leaving the cavity vacant. In cells regenerated in the treated defect, type-2 collagen, Aggrican, and SOX9 mRNAs were highly expressed and the regenerated matrix was rich in proteoglycan and type-2 collagen at 4 weeks. This fact gave a significant modification to the commonly established concept that hyaline cartilage tissue cannot regenerate in vivo. This study prompted an innovative strategy in the field of joint ON gel surgery to repair an osteochondral defect using an advanced, high-function hydrogel.
  • Tasuku Nakajima, Hidemitsu Furukawa, Yoshimi Tanaka, Takayuki Kurokawa, Yoshihito Osada, Jian Ping Gong
    MACROMOLECULES 42 (6) 2184 - 2189 0024-9297 2009/03 [Refereed][Not invited]
     
    We elucidate why the anomalous high strength of double network gels is obtained when the second network is polymerized without any cross-linkers. We have synthesized truly independent-DN gels (named "t-DN" gels), which do not have any covalent bonds between the first and the second networks, and showed that the t-DN gels cannot be toughened by the un-cross-linked second network. It means that the high strength of Usual DIN gels without the cross-linker of the second network is actually achieved by the interconnection between the two networks through covalent bonds (so usual DN gels were named "c-DN" gels). Further, we found that the t-DN gels become stronger than the c-DN gels when the second network is loosely cross-linked. As the t-DN gels have a more simple structure than the c-DN gels, we expect that the toughening mechanism of DN gels will be clarified by studying the t-DN gels in the future.
  • Kazuhiro Shikinaka, Akira Kakugo, Yoshihito Osada, Han Ping Gong
    LANGMUIR 25 (3) 1554 - 1557 0743-7463 2009/02 [Refereed][Not invited]
     
    In this paper we explored factors that determine the polarity of an Actin bundle formed with polycation through electrostatic interaction. We found that the polarity decreases with an increase in the polycation concentration while it hardly depends on the KCl salt concentration. Additionally, the polarity of the Actin bundle increases with an increase in the degree of polymerization of the polycation at a constant polymer concentration. From these results we proposed that the kinetics of nuclei formation determines the polarity of the Actin bundle.
  • Sanghun Lee, Vijay R. Tirumala, Michihiro Nagao, Taiki Tominaga, Eric K. Lin, Jian Ping Gong, Wen-li Wu
    MACROMOLECULES 42 (4) 1293 - 1299 0024-9297 2009/02 [Refereed][Not invited]
     
    Double-network hydrogels (DN-gels) prepared from the combination of a moderately cross-linked anionic polyelectrolyte (poly(2-acrylamido-2-methyl-1-propanesulfonic acid), PAMPS) and an un-cross-linked linear polymer (polyacrylamide, PAAm) Solution show strong mechanical properties far superior to that of their individual Constituents. To determine the origin of the superior properties of DN-gels, we investigated the structure and the chain dynamics of model PAMPS/PAAm solution blends using small-angle neutron scattering and neutron spin-echo measurements. Akcasu's dynamic scattering theory fora multicomponent System is modified to include polyelectrolytes, and the resulting equation describes well the neutron spin-echo results over the entire wavevector ran,ye covered in our experiments, Parameters such as effective solvent viscosity were deduced from the measured data using the modified Akcasu equation. Both the relaxation time at large length scales (10-100 nm) and the segmental diffusion coefficient at short length scales (1-10 A) or the effective solvent viscosity show good accordance with the macroscopic rheological behavior of the solution blends.
  • Yong Mei Chen, Jing Jing Yang, Jian Ping Gong
    JOURNAL OF ADHESION 85 (11) 839 - 868 0021-8464 2009 [Refereed][Invited]
     
    As soft and wet scaffolds, hydrogels are attractive materials for tissue engineering due to their similarity in structure and properties to living tissue. For designing hydrogels as potential artificial tissues, some basic requirements, such as a high level of cellular viability, suitable viscoelasticity, and high mechanical strength, are required. However, it is difficult to develop a hydrogel that satisfies even two of these requirements at the same time. In this review, our recent advances in developing synthetic hydrogels as cell culture scaffold are summarized. We found that endothelial cells (ECs) can proliferate directly on some synthetic hydrogels with negative charge, so long as the hydrogels have a Zeta potential lower than ca. -20mV, and the cell behavior can be controlled by adjusting the hydrogel's charge density. Furthermore, confluent EC monolayers cultured on the hydrogels show excellent platelet compatibility, compared with an EC monolayer cultured on a polystyrene plate. On the basis of the above study, we have further developed micro-patterned hydrogels for selective cell spreading, proliferation, and orientation. We have also developed tough hydrogels on which cells show viability. These results will promote the potential applications of synthetic hydrogels in tissue engineering.
  • Tasuku Nakajima, Takayuki Kurokawa, Hidemitsu Furukawa, Qiu Ming Yu, Yoshimi Tanaka, Yoshihito Osada, Jian Ping Gong
    CHINESE JOURNAL OF POLYMER SCIENCE 27 (1) 1 - 9 0256-7679 2009/01 [Refereed][Invited]
     
    Living tissues work with fantastic functions in soft and wet gel-like state. Thus, hydrogels have attracted much attention as excellent soft and wet materials, suitable for making artificial organs for medical treatments. However, conventional hydrogels are mechanically too weak for practical uses. We have created double network (DN) hydrogels with extremely high mechanical strength in order to overcome this problem. DN gels are interpenetrating network (IPN) hydrogels consisting of rigid polyelectrolyte and soft neutral polymer. Their excellent mechanical properties cannot be explained by the standard fracture theories. In this paper, we discuss about the toughening mechanism of DN gels in accordance with their characteristic behavior, such as large hysteresis and necking phenomenon. We also describe the results on tissue engineering application of DN gels.
  • Songmiao Liang, Qiu Ming Yu, Haiyan Yin, Zi Liang Wu, Takayuki Kurokawa, Jian Ping Gong
    CHEMICAL COMMUNICATIONS (48) 7518 - 7520 1359-7345 2009 [Refereed][Not invited]
     
    Ultrathin double-network hydrogels, which have super-high toughness under micro-scale thickness (elastic elongation epsilon(b) > 1000%, tensile strength sigma(b) > 2 MPa and tearing energy G similar to B 600 J m(-2)), and solvent-triggered fast and high isometric stress generation, were synthesized by coupling the salt-controlled swelling process and polymer chain pre-reinforced technique.
  • Yasunori Kawauchi, Yoshimi Tanaka, Hidemitsu Furukawa, Takayuki Kurokawa, Tasuku Nakajima, Yoshihito Osada, Jian Ping Gong
    Journal of Physics: Conference Series 184 12016 - (8pp) 1742-6596 2009 [Refereed][Invited]
     
    We propose a simple method to obtain double network (DN) hydrogels containing 85-90wt% water with various kinds of mechanical performance by taking advantage of the heterogeneity of the first network: By synthesizing the first network in a poor solvent that enhancing the heterogeneity of the network, the DN gel exhibits rich mechanical behavior: from brittle, ductile (necking), to paste-like. For a proper heterogeneity, a distinct necking deformation with extensibility of about 20 times is observed for post-necking gels. The necking gels have a high initial modulus (0.1-0.5 MPa) and high mechanical toughness (nominal fracture stress: 1 MPa), both values are similar to that of living tissues. © 2009 IOP Publishing Ltd.
  • Ananda Putra, Akira Kakugo, Hidemitsu Furukawa, Jian Ping Gong
    POLYMER JOURNAL 41 (9) 764 - 770 0032-3896 2009 [Refereed][Not invited]
     
    We report the effect of oxygen and viscoelasticity of culture interface on the orientation of bacterial cellulose (BC) fibril synthesized by Acetobacter xylimum (ATCC 53582) at a silicone oil/culture medium (liquid/liquid system) interface. In this work, we used the silicone oil with various kinematic viscosities, v ranging from 10 to 3000 centistokes (CS). We found that the birefringence, Delta n as a measure of degree of orientation, fibril width, w, swelling degree, q, and tensile modulus, E, increased as increase the thickness and viscosity of silicone oil. However, fracture stress, sigma(F) and fracture strain, lambda(F) decreased with increase the silicone oil thickness and viscosity. Further, we also found that viscoelasticity of culture interface plays an important role to determine the orientation alignment of BC fibrils. Meanwhile, oxygen did not show significant influence on orientation of BC fibrils.
  • T. Murosaki, T. Noguchi, K. Hashimoto, A. Kakugo, T. Kurokawa, J. Saito, Y. M. Chen, H. Furukawa, J. P. Gong
    BIOFOULING 25 (7) 657 - 666 0892-7014 2009 [Refereed][Not invited]
     
    In the marine environment, the antifouling (AF) properties of various kinds of hydrogels against sessile marine organisms (algae, sea squirts, barnacles) were tested in a long-term experiment. The results demonstrate that most hydrogels can endure at least 2 months in the marine environment. In particular, mechanically tough PAMPS/PAAm DN and PVA gels exhibited AF activity against marine sessile organisms, especially barnacles, for as long as 330 days. The AF ability of hydrogels toward barnacles is explained in terms of an `easy-release' mechanism in which the high water content and the elastic modulus of the gel are two important parameters.
  • Xufeng Ni, Ananda Putra, Hidemitsu Furukawa, Jian Ping Gong
    COMPOSITE INTERFACES 16 (4-6) 433 - 446 0927-6440 2009 [Refereed][Invited]
     
    Novel double network (DN) hydrogels were prepared via atom transfer radical polymerization (ATRP) of the first network using two different initiators, and followed by ultraviolet (UV) photo-initiated polymerization for the second network. The first networks DN hydrogels were prepared by using two different initiators; one is a one-side initiator, and the other is a double-side initiator. The mechanical properties of various DN gels, such as water content and compressive strength, were studied. The network structure of the DN hydrogels was also characterized by dynamic light scattering. Thus, we demonstrated that the ATRP method is useful to control the network structure of the first network for DN gels. Extensive inhomogeneous structure of the first network wits obtained by ATRP method and increased both the swelling degree and softness of DN gels. (C) Koninklijke Brill NV, Leiden, 2009
  • Yukari Numata, Kazumi Muromoto, Hidemitsu Furukawa, Jian Ping Gong, Kenji Tajima, Masanobu Munekata
    POLYMER JOURNAL 41 (7) 524 - 525 0032-3896 2009 [Refereed][Not invited]
  • Shinsuke Oogaki, Go Kagata, Takayuki Kurokawa, Shinya Kuroda, Yoshihito Osada, Jian Ping Gong
    SOFT MATTER 5 (9) 1879 - 1887 1744-683X 2009 [Refereed][Not invited]
     
    The friction between two like-charged polyelectrolyte gels in pure water is measured by using a normal strain-controlled rheometer with a parallel-plates geometry. The effects of normal stress, gel elasticity and sample thickness on the velocity dependence of friction between the gels are investigated. The frictional stress demonstrates strong velocity dependence (liquid-like) when the gel is soft and thick, while it demonstrates a weak or even no velocity dependence (solid-like) when the gel is rigid and thin. The former is interpreted by a combined mechanism of boundary lubrication and hydrated lubrication, wherein the thickness of the lubricating layer is velocity-independent, due to the formation of an electric double layer at the soft and repulsive interfaces. On the other hand, the latter is interpreted by a combined mechanism of boundary lubrication and elastohydrodynamic lubrication, wherein the thickness of the lubricating layer is velocity-enhanced by the water entrainment during sliding. The friction of the soft, thick sample is related to micro-contact while that of the rigid, thin sample is related to macroscopic geometric effect. This work may contribute to the science of friction between two soft and repulsive interfaces in water.
  • Yong Mei Chen, Rie Ogawa, Akira Kakugo, Yoshihito Osada, Jian Ping Gong
    SOFT MATTER 5 (9) 1804 - 1811 1744-683X 2009 [Refereed][Not invited]
     
    A series of polyNaSS-co-DMAAm) hydrogels with zeta potentials (zeta) in the range -8.8--20.5 mV and a constant Young's modulus E) of ca. 200 kPa were designed for studying the effect of the charge density of hydrogels on dynamic cell behavior. The zeta was adjusted by tuning the molar friction of negatively charged sodium p-styrene sulfonate NaSS) contained in the monomer mixture [ NaSS and N, N-dimethyl acrylamide DMAAm)] for gelation. A critical zeta potential, which controls cell behavior, zeta(crit) = -14.0 mV, was observed. When zeta > zeta(crit), the cells exhibited a small spreading area, fast migration velocity, and a large migration distance, with concurrent deficiency in actin fibers and less prominent focal adhesions. Conversely, when zeta <= zeta(crit), the cells exhibited a large spreading area, slow migration velocity, and a short migration distance, with concurrent well-developed actin fibers and prominent focal adhesions. Furthermore, cells repeatedly oscillated in a stick-slip mode from a spreading shape to a round shape on the hydrogels with zeta > zeta(crit), although were unable to proliferate. The cell behavior is well correlated with the adsorbed fibronectin on the hydrogel surfaces.
  • T. Murosaki, T. Noguchi, A. Kakugo, A. Putra, T. Kurokawa, H. Furukawa, Y. Osada, J. P. Gong, Y. Nogata, K. Matsumura, E. Yoshimura, N. Fusetani
    BIOFOULING 25 (4) 313 - 320 0892-7014 2009 [Refereed][Not invited]
     
    Barnacle (Balanus amphitrite) settlement on synthetic hydrogels with various chemical structures was tested in laboratory assays. The results demonstrated that cyprids settle less or not at all on hydrogels and PDMS elastomer compared with the polystyrene control. The low settlement on gels is most likely due to the 'easy release' of initially attached cyprids from the gel surfaces. This low adhesion of cyprids is independent of surface hydrophilicity or hydrophobicity, and of surface charge. The results also revealed that hydrogels can be categorized into two groups. One group showed an extremely strong antifouling (AF) performance that was independent of the elasticity (E) or swelling degree (q) of the gels. The second group showed relatively less strong AF performance that was E- or q-dependent. In the latter case, E, rather than the q, may be the more important factor for cyprid settlement.
  • Yong Mei Chen, Jian Ping Gong, Masaru Tanaka, Kazunori Yasuda, Sadaaki Yamamoto, Masatsugu Shimomura, Yoshihito Osada
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 88A (1) 74 - 83 1549-3296 2009/01 [Refereed][Not invited]
     
    Tough triple network (TN) hydrogels that facilitate cell spreading and proliferation and, at the same time, preserve high mechanical strength are synthesized by the introduction of a proper component of negatively charged moiety, poly(2-acrylamido-2-methyl-propane sulfonic acid sodium salt) (PNaAMPS), on which cells proliferate, with neutral moiety, poly(N,N-dimethylacrylamide) (DMAAm), on which cells do not proliferate, as the third network component, to PNaAMPS/PDMAAm double network (DN) gels. For synthesizing the tough TN gels to support cell viability, the effect of charge density on the behaviors of three kinds of cells, bovine fetal aorta endothelial cells (BFAECs), human umbilical endothelial cells (HUVECs), and rabbit synovial tissue-derived fibroblast cells (RSTFCs) were systematically investigated on poly(NaAMPS-co-DMAAm) gels with different charge density of the gels was tuned by changing the molar fraction (F) of negatively charged monomer in the copolymer hydrogels. Critical F, which corresponds to a critical value of the zeta potential (zeta), is observed for cell spreading and proliferation. The critical F for observed for cell spreading and proliferation. The critical F for BFAECs and HUVECs proliferate to confluent is F = 0.14 (zeta = -20 mV), whereas the critical F for RSTFCs shifts to F = 0.7 (zeta = -28.5 mV). The effect of gel charge density on cell behavior is correlated well with the total adsorbed proteins and fibronectin. By applying these results, cell proliferation is successfully realized on the tough TN hydrogels without surface modification with any cell adhesive proteins or peptides. The results will substantially promote the application of tough hydrogels as soft and west tissues. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 88A: 53-64, 2009
  • Yoshihito Osada, Gong Jian Ping
    20th Anniversary MHS 2009 and Micro-Nano Global COE - 2009 International Symposium on Micro-NanoMechatronics and Human Science 108 - 111 2009 [Refereed][Not invited]
  • Tominaga T, Osada Y, Gong J.P
    NATO Science for Peace and Security Series A: Chemistry and Biology 117 - 138 2009 [Refereed][Not invited]
  • 4種類のダブルネットワークハイドロゲルの圧縮ひずみ速度依存特性−関節軟骨との比較−
    藤木裕行, 臺丸谷政志, 陳 咏梅, 龔 剣萍, 長田義仁, 安田和則
    日本臨床バイオメカニクス学会誌 29 261 - 266 2008/12 [Not refereed][Not invited]
  • Wei Yang, Hidemitsu Furukawa, Jian Ping Gong
    ADVANCED MATERIALS 20 (23) 4499 - 4503 0935-9648 2008/12 [Refereed][Not invited]
     
    Novel hydrogels that possess highly ordered anisotropic structures have been synthesized by controlling the diffusion direction of multivalent ions that act as cross-linkers into a semi-rigid polyelectrolyte solution. A double network (DN) technique is then used to form highly ordered DN gels with excellent mechanical properties, e.g., an extensibility of over 2200% the original length under uniaxial elongation.
  • モータータンパク質でソフトアクチュエーター ―ナノからマクロへ―
    川村隆三, 龔剣萍
    未来材料 8 (11) 58 - 59 2008/11 [Not refereed][Invited]
  • 高強度高分子ゲルの摩擦特性 Friction properties of polymer gel with high mechanical strength
    島津英一郎, 江上正樹, 黒川孝幸, 龔剣萍
    NTNテクニカルレビュー 76 45 - 50 2008/10 [Not refereed][Not invited]
  • Hidemitsu Furukawa, Rikimaru Kuwabara, Yoshimi Tanaka, Takayuki Kurokawa, Yang-Ho Na, Yoshihito Osada, Jian Ping Gong
    MACROMOLECULES 41 (19) 7173 - 7178 0024-9297 2008/10 [Refereed][Not invited]
     
    To investigate the mechanical strength of double network (DN) gels in a wide dynamical range, the gel solvent was replaced with viscous solvents-ethylene glycol and glycerol-and with their mixtures with water. The viscosity dependence of fracture energy in a tearing test was weak but demonstrated the existence of characteristic tear velocity for maximum fracture energy as a function of solvent viscosity. Fast and slow relaxation modes in the gels' dynamics were simultaneously observed by scanning microscopic light scattering, which reveals that the DN-gel structure stays unperturbed by the solvent change. These results implied that the solvent viscosity weakly affect the toughness and structure of the DN gels. Further, we demonstrated that the effect of solvent viscosity on the fracture energy can be incorporated into a scaled tear velocity that distributes over 6 orders of magnitude. We concluded that the viscous friction between polymer and solvent is not particularly significant for the energy dissipation of DN-gel fracture.
  • Haruka Maemichi, Kazuhiro Shikinaka, Akira Kakugo, Hidemitsu Furukawa, Yoshihito Osada, Han Ping Gong
    LANGMUIR 24 (20) 11975 - 11981 0743-7463 2008/10 [Refereed][Not invited]
     
    We investigated the effects of polycation-mediated actin assembly on the morphological transformation of the lipid vesicle membrane by spatiotemporally controlling actin assembly. By triggering the radical polymerization of the cationic monomer using UV irradiation, we achieved a varied photoinduced assembly of actin in bulk solution. Furthermore, we designed liposomes containing actin and cationic monomers. In these actin-encapsulated liposomes, various actin assemblies were formed by UV irradiation similar to that observed in bulk solution. Moreover, morphogenesis of actin-encapsulated liposomes was observed in liposomes encapsulated with G-actin but not with F-actin. This result indicates that a dynamic polymerization of G-actin is important for vesicle protrusion.
  • Akira Kakugo, Kazuhiro Shikinaka, Jian Ping Gong
    INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES 9 (9) 1685 - 1703 1661-6596 2008/09 [Refereed][Invited]
     
    We present a soft bio-machine constructed from biological motors (actin/myosin). We have found that chemically cross-linked polymer-actin complex gel filaments can move on myosin coated surfaces with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. Additionally, it is shown that the velocity of polymer-actin complex gel depends on the species of polycations binding to the F-actins. Since the design of functional actuators of well-defined size and morphology is important, the structural behavior of polymer-actin complexes has been investigated. Our results show that the morphology and growth size of polymer-actin complex can be controlled by changes in the electrostatic interactions between F-actins and polycations. Our results indicate that bio actuators with desired shapes can be created by using a polymer-actin complex.
  • Hidemitsu Furukawa, Jian Ping Gong
    Advances in Science and Technology 61 40 - 45 2008/09 [Refereed][Invited]
  • Ryuzo Kawamura, Akira Kakugo, Kazuhiro Shikinaka, Yoshihito Osada, Jian Ping Gong
    BIOMACROMOLECULES 9 (9) 2277 - 2282 1525-7797 2008/09 [Refereed][Not invited]
     
    In this paper, we reveal that microtubules (MTs), reconstructed from tubulin in vitro in the presence of guanosine-5'-triphosphate (GTP), have a ring or spiral shape on a motor protein-fixed surface, and these MTs show biased motion in the counterclockwise direction. By cross-linking these MTs during the sliding motion, we obtained large ring-shaped MT assemblies, 1 similar to 12.6 mu m in diameter. The ratio of the rings rotating in the counterclockwise direction to those rotating in the clockwise direction was approximately 3/1. Under optimized conditions, the ratio was as high as 14/1. Thus, We Successfully obtained aggregated MTs with a large hierarchic structure that shows a preferential motion, through a dynamic process in vitro.
  • Yoshimi Tanaka, Yasunori Kawauchi, Takayuki Kurokawa, Hidemitsu Furukawa, Takaharu Okajima, Jian Ping Gong
    MACROMOLECULAR RAPID COMMUNICATIONS 29 (18) 1514 - 1520 1022-1336 2008/09 [Refereed][Not invited]
     
    Double-network (DN) gels, a type of interpenetrating polymer network (IPN) consisting of rigid and flexible polymer components, exhibit two outstanding mechanical behaviors: yielding deformation of the entire specimen in tensile tests and quite high fracture energy in tearing tests. In this study, atomic force microscope (AFM) measurements were conducted on DN gels to determine the local Young's moduli immediately below the fracture surfaces E-f and below the usual molded surfaces E-m, and compare the local modulus with bulk Young's moduli measured before and after the yielding deformation, denoted as E-h and E-s, respectively. E-m and E-h are around 0.1 MPa; E-f and E-s, around 0.01 MPa, one order lower than the former two moduli. The order relation indicates that yielding deformation occurred locally around the crack tip of the DN gel during fracture. This supports the basic assumption of phenomenological models recently proposed to explain high fracture energy of DN gels.
  • Daisaku Kaneko, Hidemitsu Furukawa, Yoshimi Tanaka, Yoshihito Osada, Jian Ping Gong
    Progress in Colloid Polymer Science 135 225 - 230 2008/08 [Refereed][Not invited]
  • Vijay R. Tirumala, Taiki Tominaga, Sanghun Lee, Paul D. Butler, Eric K. Lin, Jian Ping Gong, Wen-li Wu
    JOURNAL OF PHYSICAL CHEMISTRY B 112 (27) 8024 - 8031 1520-6106 2008/07 [Refereed][Not invited]
     
    A molecular mechanism is proposed for the toughness enhancement observed in double-network (DN) hydrogels prepared from poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) polyelectrolyte network and poly(acrylamide) (PAAm) linear polymer. It is an extension of, the phenomenological model set forth recently by Gong et al. (Macromolecules 2007, 40, 6658-6664). This mechanism rationalizes the changes in molecular structure of the DN gel constituents observed via in situ neutron scattering measurements, the composition dependence of the solution viscosity, and the thermodynamic interaction parameters of PAMPS and PAAm molecules obtained previously from neutron scattering studies. More specifically, this proposed mechanism provides an explanation for the observed periodic compositional fluctuations in the micrometer range induced by large strain deformation.
  • 八島 慎太郎, 中野征洋, 龔剣萍
    バイオレオロジー学会誌 22 (2) 10 - 24 2008/06 [Not refereed][Invited]
  • Novel Oriented Bacterial Cellulose Gels on Oxygen-Permeable Substrates
    Ananda Putra, Hidemitsu Furukawa, Akira Kakugo, Jian Ping Gong
    Cellulose Communications 15 (2) 73 - 78 2008/06 [Not refereed][Invited]
  • 高強度・高機能ゲルの開発とその生体材料への応用
    陳咏梅, 龔剣萍
    ファインケミカル 37 (6) 5 - 14 2008/05 [Not refereed][Invited]
  • ATP駆動型ソフトバイオマシンの創製
    角五 彰, グン剣萍, 長田義仁
    化学と工業 61 (5) 510 - 513 2008/05/01 [Not refereed][Invited]
  • Taiki Tominaga, Vijay R. Tirumala, Sanghun Lee, Eric K. Lin, Jian Ping Gong, Wen-Li Wu
    JOURNAL OF PHYSICAL CHEMISTRY B 112 (13) 3903 - 3909 1520-6106 2008/04 [Refereed][Not invited]
     
    Double-network hydrogels (DN-gels) prepared from the combination of a moderately cross-linked anionic polyelectrolyte (PE) and an uncross-linked linear polymer solution (NP) exhibit mechanical properties such as fracture toughness that are intriguingly superior to that of their individual constituents. The scheme of double-network preparation, however, is. not equally successful for all polyelectrolyte/neutral polymer pairs. A successful example is the combination of poly(2-acrylamido-2-methyl-1-propane sulfortic acid) (PAMPS) cross-linked network and linear polyacrylamide (PAAm), which results in DN-gels with fracture strength under compression approaching that of articular cartilage (, 20 MPa). Small-angle neutron scattering was used to determine the thermodynamic interaction parameters for PAMPS and PAAm in water as a first step to elucidate the molecular origin responsible for this superior property. Measurements on PAMPS/PAAm DN-gels and their solution blend counterparts indicate that the two polymers interact favorably with each other while in water. This favorable PAMPS/PAAm interaction given by the condition chi(PE-NP) << chi(PE-water) <chi(NP-water), where chi is the Flory-Huggins interaction parameter, is consistent with some of the salient features of the DN structure revealed by SANS, and it may also contribute to the ultimate mechanical properties of DN-gels.
  • Ananda Putra, Akira Kakugo, Hidemitsu Furukawa, Jian P. Gong, Yoshihito Osada
    POLYMER 49 (7) 1885 - 1891 0032-3861 2008/04 [Refereed][Not invited]
     
    On static cultivation, Acetobacter xylinum synthesizes bacterial cellulose (BC) that has a gel-like fibril network with inappropriate orientation at the air/liquid interface. This can be easily molded into desired shapes and sizes during synthesis. Here, we report a simple technique to synthesize tubular BC (BC-TS) gel with proper fibril orientation. We found that culturing BC in oxygen-permeable silicone tubes with inner diameter < 8 mm yields a BC-TS gel of the desired length, inner diameter, and thickness with uniaxially oriented fibrils. The fibrils are oriented along the longitudinal axis of the silicone tube, independent of gravity, oxygen availability, and the morphology of the inner surface of the silicone tube but dependent on the curvature of the silicone tube. The degree of orientation (Delta n) of the BC-TS fibrils, as revealed by their birefringence, increases with decrease in the inner diameter of the silicone tube. BC-TS with a uniaxially oriented fibril structure has excellent mechanical properties and holds promise for use as a microvessel or soft tissue material in medical and pharmaceutical applications. (c) 2008 Elsevier Ltd. All rights reserved.
  • Wei Yang, Hidemitsu Furukawa, Yukari Shigekura, Kazuhiro Shikinaka, Yoshihito Osada, Jian Ping Gong
    MACROMOLECULES 41 (5) 1791 - 1799 0024-9297 2008/03 [Refereed][Not invited]
     
    We investigated the self-assembling structure in aqueous solution of polyelectrolyte poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT), which has a rigid chemical structure of polyaramide in the main chain. It is found that PBDT exhibits a stretched semirigid conformation in solution, regardless of PBDT concentration, C-P, or salt addition. PBDT in water exhibits both a very low overlap concentration, C*, and a lower critical concentration of nernatic liquid crystal, C-LC*. In the intermediate region of C* < C-P < C-LC*, PBDT forms cluster-like isotropic self-assembly. Moreover, in the intermediate region of C* < C-P < C-LC*, the addition of NaCl induces the alternation of structure from a cluster-like isotropic self-assembly to a fiber-like anisotropic one. Further addition of NaCl induces a network-like huge self-assembling structure, as the stoichiometric molar ratio of [NaCl] to [NaSO3-] increases beyond 1. The semirigid polyelectrolyte probably has hidden potential for structural polymorphism in aqueous solutions in the presence of salt.
  • Yoshie Tanabe, Kazunori Yasuda, Chinatsu Azuma, Hiroko Taniguro, Shin Onodera, Akira Suzuki, Yong Mei Chen, Jian Ping Gong, Yoshihito Osada
    JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE 19 (3) 1379 - 1387 0957-4530 2008/03 [Refereed][Not invited]
     
    The study evaluated biological reaction of four types of novel double network gels in muscle and subcutaneous tissues, using implantation tests according to the international guideline. The implantation tests demonstrated that, although poly (2-acrylamide-2-metyl-propane sulfonic acid)/poly (N,N'-dimetyl acrylamide) (PAMPS/PDMAAm) gel induced a mild inflammation at 1 week, the degree of the inflammation significantly decreased into the same degree as that of the negative control at 4 and 6 weeks. This gel has a potential to be applied as artificial cartilage. In addition, Cellulose/Gelatin gel showed the same degree of inflammation as that of the negative control at 1 week, and then, showed a gradually absorbable property at 4 and 6 weeks. This gel has a potential to be applied as an absorbable implant. The PAMPS/polyacrylamide and Cellulose/PDMAAm gels induced a significant inflammation at each week. These DN gels are difficult to be applied as clinical implants in the current situation.
  • Kazuhiro Shikinaka, Hyuckjoon Kwon, Akira Kakugo, Hidemitsu Furukawa, Yoshihito Sada, Jian Ping Gong, Yoshitaka Aoyama, Hideo Nishioka, Hiroshi Jinnai, Takaharu Okajima
    BIOMACROMOLECULES 9 (2) 537 - 542 1525-7797 2008/02 [Refereed][Not invited]
     
    Three-dimensional structures of actin bundles formed with polycations were observed by using transmission electron microtomography and atomic force microscopy. We found, for the first time, that the cross-sectional morphology of actin bundles depends on the polycation species and ionic strength, while it is insensitive to the degree of polymerization and concentration of polycation. Actin bundles formed with poly-N-[3-(dimethylamino)propyl] acrylamide methyl chloride quaternary show a ribbon-like cross-sectional morphology in low salt concentrations that changes to cylindrical cross-sectional morphology with hexagonal packing of the actin filaments in high salt concentrations. Contrastingly, actin bundles formed with poly-L-lysine show triangular cross-sectional morphology with hexagonal packing of the actin filaments. These variations in cross-sectional morphology are discussed in terms of anisotropy in the electrostatic energy barrier.
  • Hidenori Noguchi, Minowa Hiroshi, Taiki Tominaga, Jian Ping Gong, Yoshihito Osada, Kohei Uosaki
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 10 (32) 4987 - 4993 1463-9076 2008 [Refereed][Not invited]
     
    Interfacial structures of water at polyvinyl alcohol (PVA) and poly(2-acrylamido-2-methypropane) sulfonic acid sodium salt (PNaAMPS)/quartz interfaces were investigated by sum frequency generation (SFG) spectroscopy. Two broad peaks were observed in OH stretching region at 3200 and 3400 cm(-1), corresponding to the symmetric OH stretching of tetrahedrally coordinated, i.e., strongly hydrogen bonded "ice-like" water, and the asymmetric OH stretching of water in a more random arrangement, i.e., weakly hydrogen bonded "liquid-like" water, respectively, in both cases. The "liquid-like" water became dominant when the PVA gel was pressed against the quartz surface. The relative intensity of the SFG signal due to the "liquid-like" water to that due to the "ice-like water" at the quartz surface modified with a self-assembled monolayer of aminopropyltrimethoxysilane (APS) became higher when the negatively charged PNaMPS gel was contacted to the APS modified quartz surface in a solution of pH = 12, where the surface was negatively charged and electrostatic repulsive interaction and low friction were present between the PNaMPS gel and the APS modified surface. It, however, did not change in a solution of pH = 2, where the surface was positively charged and electrostatic attractive interaction and very high friction were present between the PNaMPS gel and the APS modified surface. These results suggest the important role of water structure for small friction at the polymer gel/solid interface.
  • Taiki Tominaga, Takayuki Kurokawa, Hidemitsu Furukawa, Yoshihito Osada, Jian Ping Gong
    SOFT MATTER 4 (8) 1645 - 1652 1744-683X 2008 [Refereed][Not invited]
     
    We investigated the sliding friction between a soft hydrogel and rough and weakly adhesive solid substrates in a water environment. Polyvinyl alcohol (PVA) hydrogels of different elastic moduli and two sets of glass substrates with different contact angles to water, all of which varied in their surface roughness, were used. The friction measurement was performed by using a strain-controlled parallel-plate rheometer. With an increase in substrate roughness, the friction in the low velocity region increased slightly, while it decreased significantly above a critical velocity on a surface with a roughness larger than 1 mm. Below this critical velocity, the frictional stress changed with the glass substrate surface energy, while above this critical velocity, it was not sensitive to the glass substrate surface energy. The velocity-dependence of friction on rough surfaces is explained in terms of surface contact dynamics and is characterized by two velocities, i.e., nu(f) and nu(drainage). The former is determined by the cooperative diffusion constant of the gels, and the latter is by the surface roughness of the substrate and the normal pressure applied on the gel.
  • Taiki Tominaga, Naoyuki Takedomi, Hynek Biederman, Hidemitsu Furukawa, Yoshihito Osada, Jian Ping Gong
    SOFT MATTER 4 (5) 1033 - 1040 1744-683X 2008 [Refereed][Not invited]
     
    In this paper, the frictional behavior of a neutral hydrogel, polyvinyl alcohol (PVA), on smooth solid substrates with various levels of hydrophobicity have been investigated in water using a strain-controlled parallel-plate rheometer. For the sliding velocity dependence of friction, we detected a distinct friction transition on hydrophobic substrates that are strongly adhesive to the gel, while no clear transition was observed on hydrophilic substrates that are weakly adhesive to the gel. Even on the most hydrophobic substrate, the maximum frictional stress is approximately 1/10-1/5 of the gel's elastic modulus under a large normal strain of 26%. Furthermore, the frictional stress on hydrophobic substrates in the high velocity region, larger than the transition, is much lower than that on hydrophilic ones. We attempted to explain these phenomena with the help of two models: a molecular model based on the thermal fluctuations occurring during adsorption-desorption of polymers and a continuum mechanics model based on elastic dewetting and forced wetting.
  • Ananda Putra, Akira Kakugo, Hidentitsu Furukawa, Jian P. Gong, Yoshihito Osada, Tetsuya Uemura, Masafumi Yamamoto
    POLYMER JOURNAL 40 (2) 137 - 142 0032-3896 2008 [Refereed][Not invited]
     
    Acetobacterxylinum, which is an aerobic bacterium, synthesizes bacterial cellulose (BC) with unoriented microfibril network in form of gel at the air and liquid interface (BC-air). In this work, we discovered that BC gel produced on an oxygen permeable substrate of polydimethylsiloxane (PDMS) shows strong birefringence with colorful images, indicating a liquid crystal-like structure. Furthermore, we found that uni-axially oriented BC gels can be obtained by culturing the BC on the PDMS with ridged morphology. The degree of orientation of BC gels, as revealed by the birefringence, increases with the decrease in the ridge size of the PDMS substrate. An optimum ridge size of 4.5 mu m was observed where the BC gels show the highest birefringence (Delta n), the highest fracture stress (sigma), highest swelling degree (q), the lowest elastic modulus (E), and the thickest BC fibril. The optimum ridge size is related to the contour length of the bacteria cells. When the ridge size was smaller than 4.5 mu m, the Delta n steeply decreased to a value comparable to that on smooth flat PDMS mold surface. The fracture stress, sigma of the uni-axially oriented BC gel under elongation was 4.6 MPa, which was 2.3 times higher than that of BC-air (sigma = 2 MPa).
  • Integration of Biomolecular Motors: Toward an ATP Fueled Soft Moving System
    Kazuhiro Shikinaka, Ryuzo Kawamura, Akira Kakugo, Hidemitsu Furukawa, Jian Ping Gong, Yoshihito Osada
    Polymer Preprints, Japan 57 106  2008 [Not refereed][Not invited]
  • Taiki Tominaga, Vijay R. Tirumala, Eric K. Lin, Jian Ping Gong, Hidemitsu Furukawa, Yoshihito Osada, Wen-li Wu
    POLYMER 48 (26) 7449 - 7454 0032-3861 2007/12 [Refereed][Not invited]
     
    Double-network hydrogels (DN-gels) are a new class of crosslinked polymer networks with extraordinary mechanical properties while containing 80-90 vol.% water. Small-angle neutron scattering (SANS) was applied to investigate the molecular origin of the mechanical properties observed in DN-gels. We present SANS results in both deformed and undeformed conditions for a tough DN-gel made of poly-(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) and polyacrylamide (PAAm). The SANS measurements indicate that deformation of DN-gels results in periodic and mesoscale (similar to 1.5 mu m) compositional fluctuations in both PAMPS and PAAm. In addition, SANS measurements also indicate that the DN-gel constituents interact favorably with each other while in water. This favorable interaction between PAMPS and PAAm is consistent with the rheological results on solution mixtures of these two polymers. The implications of the above observations to toughening mechanisms are discussed. Published by Elsevier Ltd.
  • Mei Huang, Hidemitsu Furukawa, Yoshimi Tanaka, Tasuku Nakajima, Yoshihito Osada, Jian Ping Gong
    MACROMOLECULES 40 (18) 6658 - 6664 0024-9297 2007/09 [Refereed][Not invited]
     
    The double network (DN) gels, composed of a minor component, chemically cross-linked polyelectrolyte (first network), and the major one, linear neutral polymer (second network), exhibit anomalously high mechanical strengths. In this study, adopting the concentration of the second polymer as the experimental parameter, we investigate the relation between the mechanical strength and the dynamics of polymer concentration fluctuation. The former is measured by compression and tearing tests; the latter is measured by a special dynamic light scattering technique (called SMILS) suitable for polymer gels. The mechanical strength is enhanced when the concentration is so high that the second polymer chains strongly entangle each other. The main finding of SMILS is that the diffusion constant of the concentration fluctuation of the second polymer is increased by the existence of the first network despite the minority of the first component (<(1)/(10) in monomer ratio to the second component). This indicates that there is entanglement also between the first and the second polymers. The inter-species entanglement and inhomogeneities of the first network suggested in our previous study [Macromolecules 2004, 37, 5370] give support to the crack model concerned with yielding around the crack tip, which explains the high mechanical strength.
  • 角五彰, 剣萍, 長田義仁
    生物物理 47 (4) 253 - 258 0582-4052 2007/07/26 [Not refereed][Invited]
  • Satomi Ohnishi, Daisaku Kaneko, Jian Ping Gong, Yoshihito Osada, A. M. Stewart, Vassili V. Yaminsky
    LANGMUIR 23 (13) 7032 - 7038 0743-7463 2007/06 [Refereed][Not invited]
     
    Stick-slip friction between mica surfaces under cyclohexane vapor has been investigated with the Surface Force Apparatus. The dynamic shear stress decreased from 60 to 10 MPa with increasing relative vapor pressure (rvp) from 5% to 50%. Between a rvp of 50% and 80%, the shear stress remained at similar to 10 MPa, with a slight decrease on increasing the rvp. At a rvp greater than 80%, the values of shear stress were below 5 MPa. The stick-slip behavior was observed in the rvp range of 20% to saturation. When the rvp reached 20%, stick-slip appeared but faded out with sliding time. At a rvp greater than 50%, the stick-slip pattern was stable without fading. By taking into account the size of the meniscus formed by capillary condensation of the liquid around the contact area and the Laplace pressure, the dependence of shear stress and the stick-slip modulation on rvp suggests that the origin of the stick-slip observed in cyclohexane vapor is as follows: At a rvp greater than 50%, where stable sick-slip is observed, the stick-slip caused by the cyclohexane layering in the contact area is of essentially the same origin as that observed with mica surfaces sliding in bulk cyclohexane liquid. As with the bulk liquid experiment, decreasing the layer thickness (or the number of the layers) between the surfaces increases the shear stress at the onset of slip. In the vapor phase experiments, the stick-slip is enhanced by the increase of the negative Laplace pressure in the capillary condensed liquid, thereby forcing the surfaces toward each other more strongly with decreasing rvp. In the rvp range between 20% and 50%, where the fading stick-slip is observed, the condensate liquid seeps into the contact area under the influence of the applied tangential force and thus triggers the slip motion. Due to the small condensation volume, the liquid condensed around the contact area is exhausted in the process of repeating stick-slip. As the slip length is limited to the meniscus size, the stick-slip amplitude becomes smaller, and eventually the surfaces start sliding without stick-slip.
  • Miao Du, Yasuyuki Maki, Taiki Tominaga, Hidemitsu Furukawa, Jian Ping Gong, Yoshihito Osada, Qiang Zheng
    MACROMOLECULES 40 (12) 4313 - 4321 0024-9297 2007/06 [Refereed][Not invited]
     
    We study the friction behaviors of poly(vinyl alcohol) (PVA) gel sliding against glass surface in dilute poly(ethylene oxide) (PEO) aqueous solution with various molecular weights, M-w, and concentrations. At low sliding velocity (10(-5), 10(-1) m/s), distinct PEO polymer effects are observed: The frictional stress in PEO 2E4 (M-w = 2 x 10(4) g/mol) solutions is lower than that in pure water, decreasing with the increase in PEO concentration and reaching a minimum at the crossover concentration, c*. However, in higher molecular weight solution, PEO 4E6 (M-w = 4 x 10(6) g/mol), this friction reduction effect is only observed for very dilute concentration (0.01 c* solution), and the friction stress in higher concentration (0.1 c*, 0.30, and c* solution) is higher than that in pure water, accompanied by the appearance of "plateau". At fast sliding velocity (10(-2), 10(-1) m/s), all the friction curves in dilute PEO solution superpose with the curve in pure water, independent of M, and concentration of PEO. These results indicate that in the low sliding velocity region, where adsorption of PVA gel on glass plays the dominant role in friction, PEO chain screens the adsorption of PVA chains to glass surface. In the fast sliding velocity region, PEO chain is either extensively stretched or forms a deplete layer on the glass surface by the high shear rate, so the liquid lubrication with a viscosity of eta approximate to eta(water) prevails. The results also support the theoretical prediction that the effective concentration of PEO in the confined 2-dimentional space between get and glass interface is enhanced for high molecular weight PEO.
  • Hyuck Joon Kwon, Akira Kakugo, Takehiro Ura, Takaharu Okajima, Yoshimi Tanaka, Hidemitsu Furukawa, Yoshihito Osada, Jian Ping Gong
    LANGMUIR 23 (11) 6257 - 6262 0743-7463 2007/05 [Refereed][Not invited]
     
    We show that F-actins form three-dimensional giant network under uni-directional diffusion of polycations, at a dilute actin concentration (0.01 mg/mL) that only bundles are formed by homogeneous mixing with polycations. The mesh size of the actin network depends on polycation concentration and ionic strength, while bundle thickness of network depends only on ionic strength, which indicates that actin network is formed through nucleation-growth mechanism. The mesh size and the bundle thickness are determined by nucleus concentration and nucleus size, respectively. The atomic force microscopy measurement correlates the elasticity of the actin network, E, with the mesh size, xi, as E similar to xi(-1), while the bundle thickness, D dependence of E cannot be described by a simple scaling relation. E similar to D-6.5 when D is small and E similar to D-0.1 when D is large. Our study on the self-assembly of actin network under asymmetric polycation condition would provide the crucial insight into the organization of biopolymers in polarized condition of cell.
  • Chinatsu Azuma, Kazunori Yasuda, Yoshie Tanabe, Hiroko Taniguro, Fuminori Kanaya, Atsushi Nakayama, Yong Mei Chen, Jian Ping Gong, Yoshihito Osada
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 81A (2) 373 - 380 1549-3296 2007/05 [Refereed][Not invited]
     
    This study evaluated biodegradation properties of four novel high-toughness double network (DN) hydrogels as potential materials for artificial cartilage. Concerning each DN gel material, a total of 12 specimens were prepared, and 6 of the 12 specimens were examined to determine the mechanical properties without any treatments. The remaining 6 specimens were implanted into the subcutaneous tissue, using 6 mature female rabbits. At 6 weeks after implantation, the mechanical properties and the water content of the implanted specimens were measured. In the poly(2-acrylamide-2-methyl-propane sulfonic acid)/poly (N,N'-dimethyl acrylamide) DN gel, the ultimate stress and the tangent modulus were significantly increased from 3.10 and 0.20 MPa, respectively, to 5.40 and 0.37 MPa, respectively, with a significant reduction of the water content after implantation (94 to 91%). In the poly(2-acrylamide-2-methyl-propane sulfonic acid) /polyacrylamide DN gel and the cellulose /poly(dimethyl acrylamide) DN gel, the stress (11.4 and 1.90 MPa, respectively) and the modulus (0.30 and 1.70 MPa, respectively) or the water content rarely changed after implantation (90 and 85%, respectively). In the bacterial cellulose/gelatin DN gel, the ultimate stress was dramatically reduced from 4.30 to 1.98 MPa with a significant increase of the water content after implantation (78 to 86%). This study implied that these DN gels except for the cellulose/gelatin DN gel are potential materials that may meet the requirements of artificial cartilage. (c) 2006 Wiley Periodicals, Inc.
  • Bacterial cellulose based hydrogel for articular soft tissues
    Akira Kakugo, Jian Ping Gong, Yoshihito Osada
    Cellulose Communications 14 (2) 50 - 54 2007/04 [Not refereed][Invited]
  • Daisaku Kaneko, Masaki Oshikawa, Tetsuo Yamaguchi, Jian Ping Gong, Masao Doi
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 76 (4) 43601-1 - 43601-3 0031-9015 2007/04 [Refereed][Not invited]
     
    The frictional coefficient mu between poly(dimethylsiloxane) (PDMS) rubber and glass plate with PDMS lubricant is measured for various thickness of rubber sample. The friction coefficient of thick sample is shown to be an order of magnitude larger than that of thin sample. The phenomenon is interpreted as the transition from the hydrodynamic lubrication to the boundary lubrication.
  • Rebecca E. Webber, Costantino Creton, Hugh R. Brown, Jian Ping Gong
    MACROMOLECULES 40 (8) 2919 - 2927 0024-9297 2007/04 [Refereed][Not invited]
     
    Systematic loading and unloading experiments, in uniaxial tension and uniaxial compression, have been performed on a double-network hydrogel exhibiting a very high toughness. We observed a significant hysteresis during the first loading cycle that increased strongly with the applied maximum deformation. A large hysteresis was not observed during a second loading cycle, implying that the initial hysteresis can be attributed to the fracture of covalent bonds in the primary network. We report this type of dissipative mechanism for polymer gels for the first time. Assuming that the entire energy dissipated during the hysteresis cycle can be attributed to the fracture of network strands by a Lake-Thomas mechanism, our results suggest that the fracture and unloading of only 1% of the bonds within the network leads to a decrease of up to 80% of the number of strands. These results also demonstrate the very large degree of heterogeneity within the hydrogel network. If such a dissipative mechanism is active at the crack tip, it will most likely greatly increase the energy necessary to propagate a macroscopic crack, elucidating the origin of the toughness in these interesting materials.
  • Yukari Shigekura, Hidemitsu Furukawa, Wei Yang, Yong Mei Chen, Tatsuo Kaneko, Yoshihito Osada, Jian Ping Gong
    MACROMOLECULES 40 (7) 2477 - 2485 0024-9297 2007/04 [Refereed][Not invited]
     
    We previously discovered that isotropic monomer solution shows birefringence due to its anisotropic structure after gelation in the presence of a small amount of rod-like polyelectrolyte. Here, we focus on what mechanism is responsible for the formation of anisotropic structure during gelation. Various optical measurements are performed to elucidate the structure change during gelation. The structure before and during gelation is in situ observed by scanning microscopic light scattering, confocal laser scanning microscope, polarizing optical microscope and depolarizing small angle light scattering. It is found that the existence of a large-size structure in monomer solution with the rod-like polyelectrolyte is essentially important to induce birefringence during gelation. The possible mechanism of the anisotropic structure formation during gelation seeded by a rod-like polyelectrolyte is proposed based on the results of these observations.
  • Yong Mei Chen, Masaru Tanaka, Jian Ping Gong, Kazunori Yasuda, Sadaaki Yamamoto, Masatsugu Shimomura, Yoshihito Osada
    BIOMATERIALS 28 (10) 1752 - 1760 0142-9612 2007/04 [Refereed][Not invited]
     
    In this work we describe experiments designed to understand the human platelet adhesion to human umbilical vein endothelial cells (HUVECs) cultured on various kinds of chemically cross-linked anionic hydrogels, which were synthesized by radical polymerization. HUVECs could proliferate to sub-confluent or confluent on poly(acrylic acid) (PAA), poly(2-acrylamido-2-methyl-propane sulfonic acid sodium salt) (PNaAMPS), and poly(sodium p-styrene sulfonate) (PNaSS) gels. The proliferation behavior was not sensitive to the crosslinker concentration of the gels. However, the platelet adhesion on the HUVECs cultured on these gels showed different behavior, as revealed by human platelet adhesion test in static conditions. Only a few platelets adhered on the HUVEC sheets cultured on PNaAMPS gels with 4 and 10 mol% cross-linker concentrations, and completely no platelet adhered on the HUVEC sheets cultured on PNaSS gels with 4 and 10 mol% cross-linker concentrations. On the other hand, a large number of platelets adhered on the HUVECs cultured on PAA gels with 1, 2mol% cross-linker concentrations and PNaAMPS gel with 2mol% cross-linker concentration. Furthermore, the study showed that promote of the glycocalyx of HUVECs with transforming growth factor-beta(1) (TGF-beta(1)) decreased platelet adhesion, and degrade the glycocalyx with heparinase I increased platelet adhesion. The results suggested that the glycocalyx of cultured HUVECs modulates platelet compatibility, and the amount of glycocalyx secreted by HUVECs dependents on the chemical structure and crosslinker concentration of gel scaffolds. This result should be applied to make the hybrid artificial blood vessel composes of gels and endothelial cells with high platelet compatibility. (c) 2006 Elsevier Ltd. All rights reserved.
  • Go Kagata, Jian Ping Gong
    COLLOIDS AND SURFACES B-BIOINTERFACES 56 (1-2) 296 - 302 0927-7765 2007/04 [Refereed][Not invited]
     
    The friction between two polyelectrolyte gels carrying the same or opposite sign of charges has been investigated using a rheometer. It is found that the friction was strongly dependent on the interfacial interaction between two gel surfaces. In the repulsive interaction case, especially, the friction was extremely low. The friction behavior is attempted to be described in terms of the hydrodynamic lubrication of the solvent layer between two like-charged gel surfaces, which is formed due to the electrostatic repulsion of the two gel surfaces. From the theoretical analysis (hydrodynamic mechanism), the friction behaviors were explained qualitatively, all of the experimental results, nevertheless, could not be understood well. The viscoelastic feature of the gel and the non-Newtonian behavior of water at the friction interface are considered to be important to elucidate the gel friction. (c) 2006 Elsevier B.V. All rights reserved.
  • Hyuck Joon Kwon, Kazuhiro Shikinaka, Akira Kakugo, Hidemitsu Furukawa, Yoshihito Osada, Jian Ping Gong
    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 7 (3) 844 - 847 1533-4880 2007/03 [Refereed][Not invited]
     
    We report a soft gel machine reconstructed from muscle proteins. We have found that chemically cross-linked polymer-actin complex gel can move on myosin coated surface with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. Additionally, it is shown that the velocity and motional pattern of polymer-actin complex gel depends on the morphology of polymer-complex gels. Since the designing of functional actuator into well-defined size and morphology is important, the structural behavior of polymer-actin complexes has been investigated. This result shows that the morphology and growth size of polymer-actin complex can be controlled by change of electrostatic interaction between F-actins and polycations. Our results indicate that bio actuator with desired shape can be created by using polymer-actin complex.
  • Yong Mei Chen, Kui Chuan Shen, Jian Ping Gong, Yoshihito Osada
    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 7 (3) 773 - 779 1533-4880 2007/03 [Refereed][Not invited]
     
    Hydrogel micropatterns of 10 similar to 200 mu m in width were introduced during the polymerization of 2-acrylamido-2-methyl-propane sulfonic acid sodium salt (NaAMPS) on the surface of polyacrylamide (PAAm) gel. Behaviors of endothelial cells on the micropatterned PNaAMPS/PAAm gel surfaces were studied. Cells selectively proliferate on micropatterned PNaAMPS surface but not on PAAm surface, which requires no modification with any cell adhesive proteins or peptides. We found that decrease of the width of the micropatterns could increase the degree of anisotropic spreading of cells and the degree of cell orientation. These results demonstrated that the topographical micropatterns of hydrogel could control cell behaviors.
  • わずかな棒状高分子電解質が誘起するゲルの構造異方性
    古川英光, 重倉ゆかり, 長田義仁, 龔剣萍
    液晶 11 (2) 153 - 159 2007 [Not refereed][Invited]
  • Hyuck Joon Kwon, Kazuhiro Shikinaka, Akira Kakugo, Hidemitsu Furukawa, Yoshihito Osada, Jian Ping Gong
    CHINESE JOURNAL OF POLYMER SCIENCE 25 (1) 47 - 55 0256-7679 2007/01 [Not refereed][Invited]
     
    F-actins are semi-flexible polyelectrolytes and can be assembled into large polymer-actin complex with polymorphism through electrostatic interaction with polycations. This study investigates the structural phase behavior and the growth of polymer-actin complexes in terms of its longitudinal and lateral sizes. Our results show that formation of polymer-actin complexes is cooperative, and morphology and growth of polymer-actin complexes depend on polycation species and concentrations of polycation and salt in a constant actin concentration. We found that the longitudinal growth and lateral growth of polymer-actin complexes are dominated by different factors. This induces the structural polymorphism of polymer-actin complexes. Major factors to influence the polymorphism of polymer-actin complexes in polyelectrolyte system have been discussed. Our results indicate that the semi-flexible polyelectrolyte nature of F-actins is important for controlling the morphology and growth of actin architectures in cell.
  • Hyuck Joon Kwon, Kazuhiro Shikinaka, Akira Kakugo, Jian Ping Gong, Yoshihito Osada
    POLYMER BULLETIN 58 (1) 43 - 52 0170-0839 2007/01 [Refereed][Not invited]
     
    We have created an ATP-fueled soft gel machine constructed from muscle proteins. Chemically cross-linked gels of the polymer-actin complex of the length several decades times the length of native actin filament (F-actin) move on myosin-coated surface with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. The motility observed in muscle protein-gels suggests that one might construct a soft machine fueled by chemical energy using actin and myosin molecules as elements. We have investigated the growth process of polymer-actin complexes and the correlation between the polarity and the motility of polymer-actin complex gels.
  • Hyuck Joon Kwon, Jian Ping Gong
    CURRENT OPINION IN COLLOID & INTERFACE SCIENCE 11 (6) 345 - 350 1359-0294 2006/12 [Not refereed][Invited]
     
    Polyelectrolyte gels are charged polymer networks with macro-ions fixed on the polymer chains. In the present paper, the fundamental aspects, properties and application of negatively charged polyelectrolyte gels are reviewed, focusing on the interaction between polyelectrolyte gels and proteins, the surface friction and mechanical strength of polyelectrolyte gels. These characteristic properties of polyelectrolyte gels have considerable potential for practical application, such as soft scaffold of cells, construction of biomimetic actuator and replacement of biological tissues. (C) 2006 Elsevier Ltd. All rights reserved.
  • Yukari Shigekura, Hidemitsu Furukawa, Yongmei Chen, Yongmei Chen, Tatsuo Kaneko, Wei Yang, Jian Ping Gong, Jian Ping Gong, Yoshihito Osada
    Polymer Preprints, Japan 55 1754  2006/10/19 [Not refereed][Not invited]
     
    We focus on highly-charged rigid-rod poly(2,2′-disulfonyl-4,4′- benzidine terephthalamide)(PBDT), which behaves as mesogen in water to induce lyotropic self-organization from a very low concentrations of 2.8wt.%. By template (matrix) polymerization of N-[3-(N,N-dimethylamino)propyl]acrylamide methyl chloride quarternary (DMAPAA-Q) with a very little amount of PBDT, the polyioncomplex gels that contains ordered network structure can be synthesized. In this study, scanning microscopic light scattering shows that PBDT and DMAPAA-Q aqueous solution forms some large structure before gelation, which may be related to the gelation induced orientation.
  • Hyuck Joon Kwon, Yoshimi Tanaka, Akira Kakugo, Kazuhiro Shikinaka, Hidemitsu Furukawa, Yoshihito Osada, Jian Ping Gong
    BIOCHEMISTRY 45 (34) 10313 - 10318 0006-2960 2006/08 [Refereed][Not invited]
     
    Biopolymers such as DNA, F-actins, and microtubules, which are highly charged, rodlike polyelectrolytes, are assembled into architectures with defined morphology and size by electrostatic interaction with multivalent cations (or polycations) in vivo and in vitro. The physical origin to determine their morphology and size is not clearly understood yet. Our results show that the actin bundle formation consists of two stages: the thickness of actin bundles is determined nearly at the initial stage, while the length of actin bundles is determined later on. It is also found that the thickness of actin bundles decreases with the increase of polycation-mediated attraction between F-actins. From these results, we propose the anisotropic nucleation-growth mechanism, in which the thickness of actin bundles is determined by critical nucleus size, whereas the length of actin bundles is determined by the concentration of free actins relative to nucleus concentration. Observing that polycations are concentrated in some sites of actin bundles, which are thought to be nucleation sites to initiate the formation of actin bundles, supports this model. This anisotropic nucleation-growth mechanism of actin bundles can be broadly applied to the self-assembly of rodlike polyelectrolytes.
  • Asami Ohsugi, Hidemitsu Furukawa, Akira Kakugo, Yoshihito Osada, Jian Ping Gong
    MACROMOLECULAR RAPID COMMUNICATIONS 27 (15) 1242 - 1246 1022-1336 2006/08 [Refereed][Not invited]
     
    We have synthesized novel coacervate-droplet gels, which were applied to controlling the transportation of DNA in electrophoresis. Coacervate droplets are colloidal particles and they are usually composed of positive and negative polyelectrolytes. However, the polyzwitterion (polyampholyte) PDMAPS can form coacervate droplets in water by itself, since PDMAPS has both positive and negative charges in each side group of main chain. Coacervate droplets have a unique nature and can catch charged macromolecules such as DNA. In order to utilize the nature of the PDMAPS coacervate droplets for the catch and release of DNA, we stabilized PDMAPS droplets in gels. The droplets catch the DNA in electrophoresis and the release of DNA can be controlled by temperature and salt addition.
  • Zhouting Jiang, Taiki Tominaga, Kosuke Kamata, Yoshihito Osada, Jian Ping Gong
    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 284 56 - 60 0927-7757 2006/08 [Refereed][Not invited]
     
    The surface friction of three kinds of gellan gets, non-purified gellan gel, Ca2+ form gellan gel, and Na+ form gellan gel, has been investigated against a glass substrate in water and NaCl aqueous solution. The non-purified gellan gels exhibit the lowest friction in pure water, especially at a low sliding velocity, showing a frictional coefficient of 0.001. The frictional stresses of gellan gels increase with the increase of storage time in water or NaCl aqueous solution. Comparing with Ca2+-gellan gel and Na+-gellan gel, the non-purified gellan gel is more instable. Relatively low friction is observed in Ne-gellan gels in a salt concentration as high as 0.05 M. The low friction in a high ionic strength is attributed to the rigid double helical structure of the gel. (c) 2005 Elsevier B.V. All rights reserved.
  • YH Na, Y Tanaka, Y Kawauchi, H Furukawa, T Sumiyoshi, JP Gong, Y Osada
    MACROMOLECULES 39 (14) 4641 - 4645 0024-9297 2006/07 [Refereed][Not invited]
  • 高分子ゲルの超低摩擦
    龔剣萍
    トライボロジスト 51 (12) 867 - 872 2006 [Not refereed][Invited]
  • うなぎに学んだ超低摩擦ゲル
    武富直之, 龔剣萍
    接着の技術 26 (3) 43 - 48 2006 [Not refereed][Invited]
  • 斉藤潤二, 龔剣萍, 長田義仁
    膜 31 (6) 302 - 306 2006 [Not refereed][Invited]
  • ナノテクノロジーによる人工軟骨の創成
    室崎喬之, 龔剣萍, 長田義仁
    日本臨牀 64 (2) 206 - 214 2006 [Not refereed][Invited]
  • Hyuck Joon Kwon, Yoshihito Osada, Jian Ping Gong
    POLYMER JOURNAL 38 (12) 1211 - 1219 0032-3896 2006 [Not refereed][Invited]
     
    Polyelectrolyte gels are charged polymer networks with macro-ions fixed on polymer chains. This present paper introduces fundamental aspects, properties and application of negatively charged polyelectrolyte gels, focusing on the electrical properties of polyelectrolyte gels, diffusion of proteins in polyelectrolyte gels, interactions between polyelectrolyte gels and oppositely charged molecules, and mechanical strength of polyelectrolyte based gels. These characteristic properties of polyelectrolyte gels have considerable potential for applications, such as soft and wet scaffolds of cells, soft actuators and replacement of biological tissues.
  • Jian Ping Gong
    SOFT MATTER 2 (7) 544 - 552 1744-683X 2006 [Refereed][Invited]
     
    Biological connective tissues, such as cartilage and corneal stroma, are essentially hydrogels consisting of fibrous collagen and proteoglycans. Little is known of the surface properties of the hydrogel, although we observe fascinating tribological behavior in biological soft tissues, such as extremely low friction between animal cartilages. We consider that the role of the solvated polymer network existing in the extracellular matrix as a gel state is critically important in the specific frictional behavior of cartilages. In order to elucidate the general tribological features of a solvated polymer matrix, the friction of various kinds of hydrogels has been investigated, and very rich and complex frictional behaviors are observed. The friction force and its dependence on the load differ with the chemical structure of the gels, surface properties of the opposing substrates, and the measurement conditions, which are totally different from those of solids. Most importantly, the coefficient of friction of gels, m, varies over a wide range and exhibits very low values (mu approximate to 10(-3)-10(-4)), which cannot be obtained from the friction between two solid materials. A repulsion-adsorption model has been proposed to explain the gel friction, which says that the friction is due to lubrication of a hydrated layer of polymer chains when the polymer chain of the gel is non-adhesive (repulsive) to the substrate, and the friction is due to elastic deformation of the adsorbed polymer chain when it is adhesive to the substrate.
  • M. Oshikawa, D. Kaneko, T. Yamaguchi, H. Morita, J. P. Gong, M. Doi
    Polymer Preprints, Japan 55 (1) 1330  2006 [Refereed][Not invited]
     
    Recently, the study of the soft-matter sliding friction is increasing its importance. For example, lubrication of joints and digestive system is key issue when we make them artificially. But the mechanism of these systems is not well-understood yet. We focused on the structural dependence of soft-matter sliding friction which contains lubrication. We use rheometer for measurement in this experiment. Changing the thickness of the rubber, we measured torque(M) and normal force(N). From these values, we estimated the factional coefficient(μ=3M/2aN). Results are shown in Fig1,2. We discovered the transition of factional coefficient between 1mm rubber and 5mm rubber. In the intermediate rotational speed, the differential of factional coefficient is about 102. This differential is explained by the difference of lubricating condition.
  • Chen Y.M, Tominaga T, Kurokawa T, Gong J.P, Osada Y
    Polymer Preprints, Japan 55 (1) 2006 [Refereed][Not invited]
  • Kamada K, Tominaga T, Kurokawa T, Tada T, Furukawa H, Gong J.P, Osada Y
    Polymer Preprints, Japan 55 (2) 3216 - 3217 2006 [Refereed][Not invited]
  • Chen Y.M, Tanaka M, Gong J.P, Kazunori Y, Yamamoto S, Shimomura M, Osada Y
    Polymer Preprints, Japan 55 (2) 4860  2006 [Refereed][Not invited]
  • Yukari Shigekura, Yongmei Chen, Yongmei Chen, Daisaku Kaneko, Hidemitsu Furukawa, Jian Ping Gong, Jian Ping Gong, Yoshihito Osada, Yoshihito Osada, Tatsuo Kaneko
    Polymer Preprints, Japan 54 1525  2005/12/01 [Not refereed][Not invited]
     
    We study a novel kind of polyioncomplex gels with liquid crystalline structure. We focus on highly-charged rigid-rod poly(2,2′-disulfonyl-4, 4′-benzidine terephthalamide)(PBDT), which behaves as mesogen in water to induce lyotropic self-organization from a very low concentrations of 2.8wt.%. By template (matrix) polymerization with N-[3-(N,N-dimethylamino)propyl] acrylamide, methyl chloride quarternary (DMAPAA-Q) under the condition where the charge ratio of PBDT as a liquid crystal molecule to DMAPAA-Q as a monomer is 1:26, the gels exhibit strong birefringence. Here, the PBDT concentration in the gels is 1/20 of lower critical PBDT concentration in aqueous solution. It means that by adding a very little amount of ionic mesogen template the birefringence polyioncomplex gels that contains ordered network structure can be synthesized.
  • HJ Kwon, A Kakugo, K Shikinaka, Y Osada, JP Gong
    BIOMACROMOLECULES 6 (6) 3005 - 3009 1525-7797 2005/11 [Refereed][Not invited]
     
    F-actins are semi-flexible polyelectrolytes and can be assembled into a large polymer-actin complex with polymorphism through electrostatic interaction with polycations. This study investigates the structural phase behavior and the growth of polymer-actin complexes in terms of its longitudinal and lateral sizes in various polycation and KCl concentrations for a constant actin concentration. Our results show that the longitudinal growth and lateral growth of polymer-actin complexes, initiated by a common nucleation process, are dominated by different factors in subsequent growth process. This induces the structural polymorphism of polymer-actin complexes. Major factors to influence the polymorphism of polymer-actin complexes in polyelectrolyte systems have been discussed. Our results indicate that the semiflexible polyelectrolyte nature of F-actins is important for controlling the morphology and growth of actin architectures in cells.
  • Y Shigekura, YM Chen, H Furukawa, T Kaneko, D Kaneko, Y Osada, JP Gong
    ADVANCED MATERIALS 17 (22) 2695 - + 0935-9648 2005/11 [Refereed][Not invited]
     
    Anisotropic gels containing a very small amount of liquid crystals have been prepared. The gels exhibit strong birefringence, even after swelling, under crossed polarizers, although the monomer solutions do not (see Figure). The swollen gels have a liquid-crystal concentration (C-LC) of only 0.14 wt.-%.
  • H Tsukeshiba, M Huang, YH Na, T Kurokawa, R Kuwabara, Y Tanaka, H Furukawa, Y Osada, JP Gong
    JOURNAL OF PHYSICAL CHEMISTRY B 109 (34) 16304 - 16309 1520-6106 2005/09 [Refereed][Not invited]
     
    The mechanical strength of double network (DN) gels consisting of highly cross-linked poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) as the first component and linear polyacrylamide (PAAm) as the second component has been investigated by varying the molecular weight of the second polymer PAAm, M-w. The experimental results reveal that, for toughening of the DN gels, (1) M-w is one of the dominant parameters, (2) there is a critical value of M-w = 10(6) for a remarkable enhancement: (3) the fracture energy of DN gels with a M-w, larger than 101 reaches a value as high as 10(3) J/m(2). By plotting the strength of DN gels (fracture stress sigma and fracture energy G) against a characteristic parameter of c[eta]. where c is the average concentration of PAAm in the DN gels and [eta] is the intrinsic viscosity of PAAm. it is found that the dramatic increase in the mechanical strength of the DN gels occurs above the region where linear PAAm chains are entangled with each other. Thus, we conclude that the entanglement between the second component PAAm plays an important role of the toughening mechanism of DN gels. This result supports the heterogeneous model, which predicts the presence of "voids" of the first network PAMPS with a size much larger than the radius of the second polymer PAAm.
  • T Kurokawa, T Tominaga, Y Katsuyama, R Kuwabara, H Furukawa, Y Osada, JP Gong
    LANGMUIR 21 (19) 8643 - 8648 0743-7463 2005/09 [Refereed][Not invited]
     
    We report the surface sliding friction of a high strength gel against a glass substrate under a normal pressure range of 0.01-2.5 MPa. The friction of the gel swollen with different viscous solvents is investigated over a wide velocity range. A velocity-viscosity conversion relationship is established. From the velocity-viscosity conversion relationship, a master curve that is characteristic to the elastic-hydrodynamic transition is observed. The results indicate that the adsorption model proposed by our previous work is valid even under a pressure up to MPa orders, which is the order of pressure that a cartilage sustains in the articular joints.
  • A Kakugo, K Shikinaka, JP Gong, Y Osada
    POLYMER 46 (18) 7759 - 7770 0032-3861 2005/08 [Refereed][Not invited]
     
    We report an ATP fueled soft gel machine reconstructed from muscle proteins of actin and myosin. Chemically cross-linked actin gel filaments, several decade times the length of native actin filaments (F-actin) move along a chemically cross-linked myosin fibrous gel (1 cm long and 50 mu m in diameter) with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. The motility observed in muscle protein-gels suggests that one might reconstruct a soft machine fueled by chemical energy by using actin and myosin molecules as elementary elements. (c) 2005 Elsevier Ltd. All rights reserved.
  • YM Chen, N Shiraishi, H Satokawa, A Kakugo, T Narita, JP Gong, Y Osada, K Yamamoto, J Ando
    BIOMATERIALS 26 (22) 4588 - 4596 0142-9612 2005/08 [Refereed][Not invited]
     
    Various hydrogels without modification by any cell adhesive proteins have been investigated as cell scaffolds. The present study shows that bovine fetal aorta endothelial cells can adhere, spread, proliferate, and reach confluence on poly(acrylic acid), poly(sodium p-styrene sulfonate), and poly(2-acrylamido-2- methyl-l-propanesulfonic sodium) gels, whereas cells reach subconfluence on poly(vinyl alcohol) and poly(meth acrylic acid) gels. The proliferation behavior was sensitive to both hydrogel charge density and crosslinker concentration. The relationship between cell proliferation and zeta potential of gels was discussed. It was found that hydrogels with a negative zeta potential higher than about 20mV facilitates cell proliferation. (c) 2004 Elsevier Ltd. All rights reserved.
  • K Yasuda, JP Gong, Y Katsuyama, A Nakayama, Y Tanabe, E Kondo, M Ueno, Y Osada
    BIOMATERIALS 26 (21) 4468 - 4475 0142-9612 2005/07 [Refereed][Not invited]
     
    This study evaluated the wear property of four novel double-network (DN) hydrogels, which was composed of two kinds of hydrophilic polymers, using pin-on-flat wear testing. The gels involve PAMPS-PAAm get which consists of poly(2-acrylamide-2metyl-propane sulfonic acid) and polyacrylamide, PAMPS-PDAAAm gel which consists of poly(2-acrylamide-2-metyl-propane sulfonic acid) and poly(N,N'-dimetyl acrylamide), Cellulose/PDMAAm gel which consists of bacterial Cellulose and poly dimetylacrylamide, and Cellulose-Gelatin gel which consists of bacterial Cellulose and Gelatin. Ultra-high molecular weight polyethylene (UHMWPE) was used as a control of a clinically available material. Using a reciprocating apparatus, 10(6) Cycles of friction between a flat specimen and ceramic pin were repeated in water under a contact pressure of 0.1 MPa. To determine the depth and the roughness of the concave lesion created by wear, a confocal laser microscope was used. As a result, the maximum wear depth of the PAMPS-PDMAAm gel (3.20 mu m) was minimal in the five materials, while there was no significant difference compared to UHMWPE. There were significant differences between UHMWPE and one of the other three gels. The PAMPS-PAAm gel (9.50 mu m), the Cellulose PDMAAm gel (7.80 mu m), and the Cellulose-Gelatin gel (1302.40 mu m). This study demonstrated that the PAMPS-PDMAAm DN gel has an amazing wear property as a hydrogel that is comparable to the UHMWPE. In addition, the PAMPS-PAAm and Cellulose-PDMAAm DN gels are also resistant to wear to greater degrees than conventionally reported hydrogels. On the other hand, this study showed that the Cellulose-Gelatin DN gel was not resistant to wear. (c) 2004 Elsevier Ltd. All rights reserved.
  • Y Tanaka, R Kuwabara, YH Na, T Kurokawa, JP Gong, Y Osada
    JOURNAL OF PHYSICAL CHEMISTRY B 109 (23) 11559 - 11562 1520-6106 2005/06 [Refereed][Not invited]
     
    The fracture energy G of double network (DN) gels, consisting of poly(2-acrylamido-2-tnethylpropanesulfonic acid) (PAMPS) as the first network and poly(acrylamide) (PAAm) as the second network, was measured by the tearing test as a function of the crack velocity V. The following results were obtained: (i) The fracture energy G ranges from 10(2) to similar to 10(3) J/m(2), which is 100-1000 times larger than that of normal PAAm gels (10 J/m(2)) or PAMPS gels (10(-1) J/m(2)) with similar polymer concentrations to the DN gels. (ii) G shows weak dependence on the crack velocity V. (iii) G at a given value of V increases with decreasing of cross-linking density of the 2nd network. The measured values of G were compared with three theories that describe different mechanisms enhancing the fracture energy of soft polymeric systems. A mechanism relating to a heterogeneous structure of the DN gel is convincing for the remarkable large values of G.
  • A Kakugo, K Shikinaka, N Takekawa, S Sugimoto, Y Osada, JP Gong
    BIOMACROMOLECULES 6 (2) 845 - 849 1525-7797 2005/03 [Refereed][Not invited]
     
    The polarity of polymer-actin complexes obtained by mixing F-actin with synthetic polymers carrying positive charges such as poly(L-lysine), x,y-ionene bromide polymers, and poly{N-[3-(dimethylamino)propyl]-acrylamide} (PDMAPAA-Q) have been investigated. Actin complexes formed with poly(L-lysine) and PDMAPAA-Q, which carry charges on their side chains, show a higher polarity than those formed with x,y-ionene bromide polymers, which have charges on their chain backbones. All these polymer-actin complex gels show motility on the surfaces coated with myosin by coupling to adenosine 5'-triphosphate hydrolysis. A linear correlation between the polarity of polymer-actin complex gels and the motility is observed.
  • D Kaneko, JP Gong, M Zrinyl, Y Osada
    JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 43 (5) 562 - 572 0887-6266 2005/03 [Refereed][Not invited]
     
    The spontaneous spreading of non-film-forming fluids on the surfaces of aqueous solutions of poly(2-acrylamido-2-methyl-propanesulfonic acid) and its chemically crosslinked gels was studied. The experiments were performed in the same concentration range for the solutions and gels, far above the overlap concentration of the polymer solutions. The leading edge (R) of the spreading liquid showed a power-law behavior with time t: R = K(t + c)(alpha), where alpha is the spreading exponent and K is the spreading prefactor. alpha and K were significantly different for the polymer solutions and gels. Here c was a constant that depended on the initial conditions of the spreading liquids. Depending on the polymer concentration, alpha of the polymer solutions varied between the upper (3/4) and lower (1/10) theoretical limits for viscose liquids and solids, respectively. This indicates that no universal scaling law exists for the spreading process on viscoelastic surfaces. On the polymer gels, which were elastic substrates, universal values of alpha could be observed and could be expressed as R proportional to (t + c)(0.45) and R proportional to (t + c)(0.3) for miscible and nonmiscible spreading liquids, respectively; they showed no dependence on the polymer concentration or network mesh size. This shows that on an elastic gel surface, spreading is more or less similar to that on a solid surface. (C) 2005 Wiley Periodicals, Inc.
  • D Kaneko, T Tada, T Kurokawa, JP Gong, Y Osada
    ADVANCED MATERIALS 17 (5) 535 - + 0935-9648 2005/03 [Refereed][Not invited]
     
    High-strength, low-frictional-coefficient gels are produced by adding a third component to a double-network gel (DN gel), of either a weakly crosslinked network or non-crosslinked linear chains (to produce, respectively, a triple-network gel (TN gel) and a DN-L gel, see Figure). All the gels are highly transparent. The DN-L gel shows a fracture strength as high as 9 MPa and its frictional coefficient is as low as 10(-5) under an extremely high pressure of the order of sub-MPa.
  • Kazuhiro Shikinaka, Akira Kakugo, Jian Ping Gong, Yoshihito Osada
    e-Journal of Surface Science and Nanotechnology 3 51 - 54 1348-0391 2005/02/14 [Not refereed][Not invited]
     
    There are two basic differences in the motion between a human-made machine and a biological motor. One is in their principles. The motion of a human-made machine, which is constructed from hard and dry materials such as metals, ceramics or plastics, is realized by the relative displacement of the macroscopic constitute parts of the machine. In contrast to this, the motion of a living organism, which consists of soft and wet protein and tissues, is caused by the molecular deformation that is integrated to a macroscopic level through its hierarchical structure. The other is in their energy sources. The human-made machine is fueled by electrical or thermal energy with efficiency around 30%, but a biological motor is driven by direct conversion from the chemical energy with efficiency as high as 80-90%. In order to create biomimetic motility systems, polymer gels have been employed using their reversible size and shape change, thereby realizing the motion by integrating the deformation on a molecular level. Along this line, several kinds of artificial soft machines have been constructed using synthetic polymer gels in the past years. Gelooper (gel-looper), gelf (gel golf), gel valves, chemical motor, etc., are examples. However, the lack of hierarchical structures and energy sources inside the gel lead to a decreased response and restricts the further application of such actuators for practical use in human bodies. Here we report an ATP fueled soft gel machine reconstructed from muscle proteins of actin and myosin. Chemically cross-linked actin gel filaments, several decade times the length of native actin filaments (F-actin) move along a chemically cross-linked myosin fibrous gel (1 cm long and 50μm in diameter) with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. The motility observed in muscle protein-gels suggests that one might reconstruct a soft machine fueled by chemical energy by using actin and myosin molecules as elementary elements. © 2005 The Surface Science Society of Japan.
  • Yang-Ho Na, Yoshinori Katsuyama, Rikimaru Kuwabara, Takayuki Kurokawa, Yoshihito Osada, Mitsuhiro Shibayama, Jian Ping Gong
    e-Journal of Surface Science and Nanotechnology 3 8 - 11 1348-0391 2005/01/08 [Not refereed][Not invited]
     
    Hydrogels are made of swollen polymer networks containing more than 90% water. If modified with free chains on their surface, gels exhibit low surface friction and thus have been attractive candidates as artificial cartilage and low frictional materials. However, most hydrogels are mechanically too weak to be used as any load bearing devices. We have overcome this problem by synthesizing hydrogels with a double network (DN) structure. Despite of 90% water, these tough gels exhibit a fracture stress of 170 kg/cm 2, similar to that of cartilage. Extremely high mechanical property is due to peculiarly inhomogeneous structure of DN gels. The inhomogeneous structure is thought that large 'voids' of the first network may exist, and the second polymers exist in 'voids' of first network act as 'molecular crack-stopper' in DN gels, keeping the crack from growing to a macroscopic level. © 2005 The Surface Science Society of Japan.
  • ゲルの極低摩擦
    龔 剣萍, 長田義仁
    日本機械学会誌 108 (1042) 28 - 29 2005 [Not refereed][Invited]
  • 龔剣萍
    日本ゴム協会誌 78 (4) 130 - 134 2005 [Not refereed][Invited]
  • Y Tanaka, JP Gong, Y Osada
    PROGRESS IN POLYMER SCIENCE 30 (1) 1 - 9 0079-6700 2005/01 [Not refereed][Invited]
     
    Three kinds of novel hydrogels with excellent mechanical performance have been developed, based on different concepts. Two of them exhibit high resistance to extension, up to 10-20 times the original length, by introducing special cross-linking structures. The third has a high modulus (sub-megapascal), with a failure compressive stress as high as 20 MPa, through a double network structure. In this article, we describe the structural and mechanical features of these gels, and the status of current studies (C) 2005 Elsevier Ltd. All rights reserved.
  • A Kakugo, S Sugimoto, K Shikinaka, JP Gong, Y Osada
    JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 16 (2) 203 - 218 0920-5063 2005 [Refereed][Not invited]
     
    Myosin gels, 10 mm x 10 mm x 1 mm in size, were obtained by chemical cross-linking of scallop myosin using 1-ethyl-3-(3-dimethylaminoprolyl) carbodiimide hydrochloride (EDC), glutaraldehyde (GA), or transglutaminase (TG). All myosin gels showed high Mg-ATPase activity, although it sensitively depended on the species of cross-linker used. Among cross-linkers used, myosin gel cross-linked by TG showed the highest sensitivity, almost as high as that of native myosin. The motility assay of native actin filament on the myosin gel showed that all these myosin gels can give motion to actin filament. Among them the one cross-linked by TG had the highest average velocity and the lowest threshold concentration of ATP for movement of the actin filament and the values are nearly the same as that of native myosin. In order to give the actin filament motion with preferential direction, we attempted to make myosin gel with oriented structure by applying a shear stress. Myosin gel with oriented filament array 1 cm long and 50 pm in diameter was obtained. We found that actin filaments prefer to move along the axis of the oriented myosin gel with an increased velocity.
  • Du M, Tominaga T, Maki Y, Furukawa H, Gong J.P, Osada Y
    Polymer Preprints, Japan 54 (1) 2005 [Refereed][Not invited]
  • Tominaga T, Furukawa H, Gong J.P, Mayama H, Tsujii K, Osada Y
    Polymer Preprints, Japan 54 (2) 2005 [Refereed][Not invited]
  • Kamada K, Tominaga T, Kurokawa T, Tada T, Furukawa H, Gong J.P, Osada Y
    Polymer Preprints, Japan 54 (2) 4666 - 4667 2005 [Refereed][Not invited]
  • Yoshihito Osada, Jian Ping Gong, Yutaka Tanaka
    Journal of Macromolecular Science Part C-Polymer Reviews C44 (1) 87 - 112 2004/12 [Not refereed][Invited]
  • A Nakayama, A Kakugo, JP Gong, Y Osada, M Takai, T Erata, S Kawano
    ADVANCED FUNCTIONAL MATERIALS 14 (11) 1124 - 1128 1616-301X 2004/11 [Refereed][Not invited]
     
    Double-network (DN) hydrogels with high mechanical strength have been synthesized using the natural polymers bacterial cellulose (BC) and gelatin. As-prepared BC contains 90% water that can easily be squeezed out, with no more recovery in its swelling property. Gelatin gel is brittle and is easily broken into fragments under a modest compression. In contrast, the fracture strength and elastic modulus of a BC-gelatin DN gel under compressive stress are on the order of megapascals, which are several orders of magnitude higher than those of gelatin gel, and almost equivalent to those of articular cartilage. A similar enhancement in the mechanical strength was also observed for the combination of BC with polysaccharides, such as sodium alginate, gellan gum, and i-carrageenan.
  • Tomohiro Tada, Daisaku Kaneko, Jian Ping Gong, Tatsuo Kaneko, Yoshihito Osada
    Tribology Letters 17 (3) 505 - 511 1023-8883 2004/10 [Refereed][Not invited]
     
    The surface sliding friction of chemically cross-linked poly(dimethyl siloxane) (PDMS) swollen with linear PDMS as an oligomer is investigated. The friction force f increases with the normal pressure P in a power-law relation f∝ Pα, where the exponent α changes in a range of 0-1, depending on the degree of polymerization, Npoly, of the linear PDMS oligomer. When Npoly is in a range of 240-320, a dramatic decrease in friction force is observed at a critical normal pressure, Pc, leading to a very low friction coefficient on the order of 10-3 at high-pressure ranges. The Pc increases with decreasing network size Nnet of the gel and also with increasing polymer length related to Npoly. One possible explanation for this transition phenomenon in friction is that linear PDMS molecules are exuded from the gel network beyond a certain pressure and behave as polymer brushes, which are able to reduce the friction. © 2004 Springer Science+Business Media, Inc.
  • Y Ohsedo, R Takashina, JP Gong, Y Osada
    LANGMUIR 20 (16) 6549 - 6555 0743-7463 2004/08 [Refereed][Not invited]
     
    Hydrogels of poly(2-hydroxyethyl methacrylate) (PHEMA) with well-defined polyelectrolyte brushes of poly(sodium 4-styrenesulfonate) (PNaSS) of various molecular weights were synthesized, keeping the distance between the polymer brushes constant at ca. 20 nm. The effect of polyelectrolyte brush length on the sliding friction against a glass plate, an electrorepulsive solid substrate, was investigated in water in a velocity range of 7.5 x 10(-5) to 7.5 x 10(-2) m/s. It is found that the presence of polymer brush can dramatically reduce the friction when the polymer brushes are short. With an increase in the length of the polymer brush, this drag reduction effect only works at a low sliding velocity, and the gel with long polymer brushes even shows a higher friction than that of a normal network gel at a high sliding velocity. The strong polymer length and sliding velocity dependence indicate a dynamic mechanism of the polymer brush effect.
  • YH Na, T Kurokawa, Y Katsuyama, H Tsukeshiba, JP Gong, Y Osada, S Okabe, T Karino, M Shibayama
    MACROMOLECULES 37 (14) 5370 - 5374 0024-9297 2004/07 [Refereed][Not invited]
     
    The dynamic aspect of double network (DN) gels showing an extremely high mechanical strength has been investigated by dynamic light scattering (DLS) measurements. The DN gels are formed from highly cross-linked poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) as the first network and loosely cross-linked (or non-cross-linked) polyacrylamide (PAAm) as the second network. The results of DLS show that the presence of slow mode besides the gel mode (fast mode) enhances the strength of DN gels at the low cross-linking density of the second network. The dynamics of the slow mode cannot be explained in terms of reptational motion of the second component in the first network, but it is similar to the translational motion of PAAm polymers in a semidilute solution. A strong velocity dependence of the mechanical strength is observed at a shear rate close to the inverse of the relaxation time of the slow mode. These results suggest that large "voids" of the first network may exist, and PAAm polymers that exist in "voids" act as a "molecular crack stopper" in DN gels, keeping the crack from growing to a macroscopic level.
  • T Funaki, T Kaneko, K Yamaoka, Y Ohsedo, JP Gong, Y Osada, Y Shibasaki, M Ueda
    LANGMUIR 20 (15) 6518 - 6520 0743-7463 2004/07 [Refereed][Not invited]
  • Tatsuo Kaneko, Kanji Yamaoka, Yoshihito Osada, Jian Ping Gong
    Macromolecules 37 (14) 5385 - 5388 0024-9297 2004/06 [Refereed][Not invited]
  • 高強度低摩擦ソフトマテリアルの創製とその人工半月板への応用
    桑原力丸, 安田和則, 龔剣萍, 長田義仁
    医学のあゆみ 221 (7) 771 - 772 2004 [Not refereed][Invited]
  • T Kaneko, H Nagasawa, JP Gong, Y Osada
    MACROMOLECULES 37 (1) 187 - 191 0024-9297 2004/01 [Refereed][Not invited]
     
    Copolymers composed of 5-acryloyloxypentyl cholesterate (Ch5A) and acrylic acid (AA), poly(Ch5A-co-AA)s, were prepared changing their molar ratio, and their mesomorphic behaviors were investigated. Wide- and small-angle X-ray diffraction studies showed that poly(Ch5A-co-AA)s with a Ch5A mole fraction, F, of 0.20 and larger showed the smectic A phase in which side chains are arranged perpendicularly to the main-chain axis forming bilayers. The structural ordering and the clearing temperature, T-c, increased with decreasing F. The copolymers with F of around 0.10 exhibited a mesophase showing extremely high T-c and longer periodic spacing than the SmA phase. The copolymers of F = 0.05 and higher were not dissolved in water but swelled to form hydrogels with mesomorphic properties, presumably due to the physical cross-linking of hydrophobic aggregates of Ch5A side chains. The relationship between the uncommon thermotropic behavior and the mesomorphic structure formed by the specific interaction of chiral Ch5A components was discussed.
  • YM Chen, Y Katsuyama, JP Gong, Y Osada
    JOURNAL OF PHYSICAL CHEMISTRY B 107 (49) 13601 - 13607 1520-6106 2003/12 [Refereed][Not invited]
     
    Kinetic studies of cationic surfactant uptake by anionic polymer gel membrane under various shear flow have been performed, varying the alkyl chain length of surfactant, the ionic strength of surfactant solution, and the charge density of gel. By exposing the gel surface to a shear flow of ca. 1 Pa, the rate of surfactant uptake is distinctly enhanced, while the maximum binding ratio to the gel is not influenced. A linear relationship between the surfactant initial flux and shear stress has been established. At a high ionic strength, the effect of shear stress is suppressed, suggesting that the enhancement of surfactant uptake under shear flow is caused by a decrease in the surface electrostatic potential of the negatively charged polyelectrolyte get, which favors the uptake of the positively charged surfactant. From the Nernst and Planck equation, a relationship between the surfactant uptake kinetics and the electrostatic field is derived that allows us to estimate the shear stress dependence of the change in the electrostatic field on the gel surface. The origin of the shear-induced surface electrostatic field change is discussed.
  • A Kakugo, K Shikinaka, K Matsumoto, JP Gong, Y Osada
    BIOCONJUGATE CHEMISTRY 14 (6) 1185 - 1190 1043-1802 2003/11 [Refereed][Not invited]
     
    Polymer-actin complexes as large as 10-50 mum with filamentous, branched, stranded, and ring shapes are obtained when fluorescent phalloidin-labeled F-actin is mixed with some synthetic polymers carrying positive charges such as poly-L-lysine, x,y-ionene bromide polymers. All growth of these complexes occurs cooperatively at some certain critical polymer concentrations, regardless of the chemical structure of the polymer, while the morphology of the complexes is substantially influenced by the chemical structure of the polymer. Poly-Lys-actin complex grows preferentially along the filament axis even above the critical concentration. 3,3-ionene-actin complexes show completely homogeneous filaments below the critical concentration but forms bundles at a higher concentration. Occasionally, ring shape complexes can be observed in the 6,6-ionene-actin complex.
  • YM Chen, S Matsumoto, JP Gong, Y Osada
    MACROMOLECULES 36 (23) 8830 - 8835 0024-9297 2003/11 [Refereed][Not invited]
     
    Copolymers consisting of acrylic acid (AA) and 12-acryloyldodecanoic acid (ADA) [poly(ADA-co-AA)] were synthesized, and their dissociation behaviors and binding characteristics with ionic surfactant, dodecylpyridinium. chloride, were investigated. The dissociation is strongly suppressed in the presence of ADA, and when the ADA molar fraction (F-ADA) is 0.5, the copolymer exhibits a distinct two-stage dissociation associated with AA and ADA. The binding process is also changed by the presence of ADA. When the ADA content is low, the surfactants bind cooperatively to form a stoichiometric complex. An increase in ADA content brings about noncooperative and nonstoichiometric complexion. The initiation constant (K-0) for an isolated surfactant binding to poly(ADA(F-ADA = 1.0)) is more than 3 orders of magnitude larger than that of poly(AA(FADA = 0)), indicating that the initiation of the binding is associated not only with the electrostatic interaction but also with the hydrophobic interaction between the alkyl chains of surfactant and ADA. The structure of surfactant-poly(ADA-co-AA) complexes changes from micelle-like to lamellar-like with the increase in F-ADA.
  • D Kaneko, T Narita, JP Gong, Y Osada, J Ando, K Yamamoto, S Ohnishi, VV Yaminsky
    JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 41 (22) 2808 - 2815 0887-6266 2003/11 [Refereed][Not invited]
     
    The effect of the shear flow on the thickness change of a polyelectrolyte membrane grafted onto a glass substrate was directly investigated with a flow cell combined with a confocal laser scanning microscope. The membrane thickness decreased proportionally to an increase in the shear stress of the flow when the shear rate exceeded a critical value of 1 s(-1). The higher the ionic strength was of the fluid, the greater the thinning effect was. The correlation between the critical shear rate and the relaxation of the polymer in the gel membrane was examined. (C) 2003 Wiley Periodicals, Inc.
  • L Chen, JP Gong, Y Ohsedo, Y Osada
    MACROMOLECULAR CHEMISTRY AND PHYSICS 204 (17) 2142 - 2146 1022-1352 2003/11 [Refereed][Not invited]
     
    The water-swollen poly(AA3T-co-NaSS) and poly(AA3T-co-PEG) gels were synthesized by radical copolymerization of the monomer, [(2,2:5',2"-terthiophen-5-yl)methyl acrylate] (AA3T), containing pendant terthiophenes as an electron-conducting material with a soluble monomer, sodium p-styrenesulfonate (NaSS), or oligo(ethylene glycol) (PEG); their swelling, spectral, and doping behaviors were investigated. The degree of swelling of the poly(AA3T-co-PEG) gel was independent of the pH, whereas that of poly(AA3T-co-NaSS) gel increases abruptly below pH 3, which suggests self-doping between the AA3T and NaSS groups. The self-doping is not suppressed by cross-linking. Both poly(AA3T-co-NaSS) and poly(AA3T-co-PEG) gels can be chemically doped with concentrated HCl or HClO4 solution.
  • T Kaneko, A Ichikawa, JP Gong, Y Osada
    MACROMOLECULAR RAPID COMMUNICATIONS 24 (13) 789 - 792 1022-1336 2003/09 [Refereed][Not invited]
     
    The complexation of bile acids with various solvated polycations was studied. A one-to-one complex was precipitated when an aqueous solution of cholic acid sodium salt (CA) was mixed with aqueous solutions of 3,3-ionene and grew to form crystals with needle-like morphology, 3 millimeters in length. Hydrogen bonding of hydroxyls at the steroid face and the spacing between cationic sites of polycations were crucial for the formation of the giant needle.
  • K Yamaoka, T Kaneko, JP Gong, Y Osada
    LANGMUIR 19 (20) 8134 - 8136 0743-7463 2003/09 [Refereed][Not invited]
     
    A stretching test of the hydrogel with a smectic A (SmA) type of liquid crystalline structure, poly(11-cyanobiphenyloxyundecyl acrylate-co-acrylic acid), poly(11CBA-co-AA), was carried out in terms of various water contents. It was found that Young's modulus of the hydrogel substantially decreased with increasing the swelling degree, q, but suddenly jumped up at q = 1.13. Wide- and small-angle X-ray diffraction studies revealed that the hydrogel underwent a mesophase transition from the SmA to smectic I (SmI) phase between these q values. When the samples were further stretched, the backward transition from the SmI to SmA phase occurred accompanied by "necking". The possible mechanism of the tension-induced mesophase transition is proposed.
  • G Kagata, JP Gong, Y Osada
    JOURNAL OF PHYSICAL CHEMISTRY B 107 (37) 10221 - 10225 1520-6106 2003/09 [Refereed][Not invited]
     
    An extensive static friction has been observed when two like-charged polyelectrolyte gels are slid over each other in water. The two like-charged gel surfaces could not slip with each other at the initial shearing until the shear stress acting on the interface exceeded a certain critical value. The critical yield shear stress (static friction) and strain did not show a distinct dependence on the shearing rate but decreased with increasing temperature. The value of the static friction also increased with the increase in the normal pressure and effect of pressure becomes more substantial at a higher temperature. Furthermore, the static friction decreased 3-4 times when the counterions of the polyelectrolyte gels were changed from Na+ to Cs+. The observation of the static friction indicates that our previously proposed repulsion-adsorption model, which predicts a hydrodynamic mechanism with no static friction for two like-charged hydrogels in pure water, requires modification. Possible origins of the static friction are discussed.
  • Go Kagata, Jian Ping Gong, Yoshihito Osada
    J. Phys. Chem. B 107 (37) 10221 - 10225 1089-5647 2003/08 [Refereed][Not invited]
  • JP Gong, Y Katsuyama, T Kurokawa, Y Osada
    ADVANCED MATERIALS 15 (14) 1155 - + 0935-9648 2003/07 [Refereed][Not invited]
     
    Very strong hydrogels (with a fracture strength of some tens of MPa), as required for both industrial and biomedical applications, have been generated by inducing a double-network (DN) structure for various combinations of hydrophilic polymers. The Figure shows a hydrogel before, during, and after application of a fracture stress of 17.2 MPa.
  • Jian Ping Gong, Go Kagata, Yoshihito Osada
    Macromolecular Symposia 195 209 - 216 1022-1360 2003/06 [Not refereed][Invited]
     
    The friction between two chemically cross-linked polyelectrolyte gels carrying the same sign of charges has been investigated in pure water as well as in salt solutions using a rheometer. It is found that the friction was largely dependent on the charge densities of the gel surface and the ionic strength of the aqueous solution. The chemical structures of the polyelectrolyte gels also play an important role. The friction is described in terms of the hydrodynamic lubrication of the solvent layer between the two gel surfaces, which is formed due to the electrostatic repulsion of the two gel surfaces. The thickness of the solvent layer has been estimated using the Poisson-Boltzmann equation supposing that the ionic osmotic pressure is balanced by the normal pressure applied on the gel. The friction values have been calculated by considering the shear flow of solvent in gel region using the Debye-Binkman equation. For strongly charged polyelectrolyte gels swollen in pure water, the theoretical analysis shows that the friction coefficient almost has no dependence on the water content of the gel, which well agrees with the experimental observations.
  • L Chen, JP Gong, Y Ohsedo, Y Osada
    MACROMOLECULAR CHEMISTRY AND PHYSICS 204 (4) 661 - 665 1022-1352 2003/03 [Refereed][Not invited]
     
    A chemically cross-linked and water-swollen poly(AA3T-co-AA) gel having pendant terthiophenes was synthesized by radical copolymerization of [(2.2':5',2"-terthiophen-5-yl-)methyl acrylate] (AA3T) and acrylic acid (AA), and its swelling, dissociation, and doping behaviors were studied. The gel swells in high pH solution, which is associated with the dissociation and, hence, electrostatic repulsion of the AA units and the pH value at which the swelling starts increases with increasing AA3T composition. The dissociation of the gels is suppressed, presumably due to the incorporation of the hydrophobic AA3T unit, and, once started, the dissociation could be promoted by AA3T in the low pH region. Poly(AA3T-co-AA) copolymers and gels can be easily electrochemically and chemically doped. The volume change of the gels is observed during doping/undoping and the maximum volume change reached was about 50%.
  • ソフトアンドウェットマター−ゲル−の摩擦
    富永大輝, 龔剣萍, 長田義仁
    表面 40 (9) 317 - 323 2003 [Not refereed][Invited]
  • 筋肉タンパクによるゲルマシーンの創製
    角五彰, 龔剣萍, 長田義仁
    化学工業 55 (4) 34 - 42 2003 [Not refereed][Invited]
  • 筋肉タンパクによるナノバイオマシーンの創製
    敷中一洋, 角五彰, 龔剣萍, 長田義仁
    Bio Medical Quick Review Net. 2003 [Not refereed][Invited]
  • 龔剣萍, 長田義仁
    高分子 52 711 - 716 2003 [Not refereed][Invited]
  • P Mao, PG Jian, Y Osada
    CHEMICAL RECORD 3 (1) 40 - 50 1527-8999 2003 [Not refereed][Invited]
     
    It was found that when an aqueous solution of vinyl monomers is polymerized on a hydrophobic substrate, obvious heterogeneity occurs in the region of the interface. This substrate effect was observed on polytetrafluroethylene (Teflon), polypropylene (PP), polyethylene (PE), polystyrene (PS), and polyvinylchloride (PVC), but not on hydrophilic substrates. Compared with synthesis on hydrophilic surfaces, the surfaces of hydrogels synthesized on a hydrophobic substrate exhibit a larger degree of swelling, a lower surface coefficient of friction and elastic modulus, weaker interfacial adhesion, and reduced interaction with biological cells. This substrate effect has been observed for many types of aqueous monomer solutions. It was found that the above properties are related to the loosely cross-linked architecture, containing some graft-like polymer chains, that is formed on the gel surface when the gel is prepared on a hydrophobic substrate. To understand the mechanism of the substrate effect, two novel optical methods, electric speckle pattern interferometry (ESPI) and real-time laser sheet refraction (RT-LSR), were developed. It was found that oxygen trapped in the composite interface between the monomer solution and rough hydrophobic substrates played an important role in the substrate effect. (C) 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.
  • T Kurokawa, JP Gong, Y Osada
    MACROMOLECULES 35 (21) 8161 - 8166 0024-9297 2002/10 [Refereed][Not invited]
     
    Cross-linked poly(N,N'-dimethyl acrylamide) hydrogels were prepared on hydrophilic silicon substrates or hydrophobic polystyrene substrates and their topographical elastic properties were investigated by atomic force microscopy (AFM). The gels prepared on the hydrophobic substrate have a much rougher surface morphology with a lower surface elastic modulus than those prepared on the hydrophilic substrate. The topographical and mechanical properties of the gel have little influence on the surface friction, and the lower surface friction observed for the gel prepared on the hydrophobic substrate was attributed to the presence of dangling free polymer chains formed in the course of the polymerization.
  • D Kaneko, JP Gong, Y Osada
    JOURNAL OF MATERIALS CHEMISTRY 12 (8) 2169 - + 0959-9428 2002/08 [Not refereed][Invited]
  • A Kakugo, S Sugimoto, JP Gong, Y Osada
    ADVANCED MATERIALS 14 (16) 1124 - 1126 0935-9648 2002/08 [Refereed][Not invited]
  • Akira Kakugo, Shin Sugimoto, Jian Ping Gong, Yoshihito Osada
    Advanced Materials 14 (16) 1124 - 1126 1744-7933 2002/08 [Refereed][Not invited]
  • Yoshinori Katsuyama, Takayuki Kurokawa, Tatsuo Kaneko, Jian Ping Gong, Yoshihito Osada, Norishige Yotsukura, Taizo Motomura
    Macromolecular Chemistry and Physics 203 163 - 169 1022-1352 2002/06/10 [Not refereed][Not invited]
     
    The inhibition of germination and development of zoospores originating from Laminaria angustata originated on various kinds of hydrogels is studied. The effects of the water content of the gel (the degree of swelling), the electrical nature (neutral, positive charge, negative charge), the charge density, the counterions of hydrogels on the inhibition of zoospore germination and development of gametophytes are phenomenologically investigated. Among the gels investigated, poly(acrylic acid) (PAA) gel showed a dramatic inhibition to germination, and might serve as a novel, environmentally safe inhibitor of zoospore adhesion.
  • Takashi Miyazaki, Kanji Yamaoka, Jian Ping Gong, Yoshihito Osada
    Macromol. Rapid Commun. 23 (8) 447 - 455 1022-1336 2002/06 [Not refereed][Invited]
  • KANEKO Tatsuo, YAMAOKA Kanji, GONG Jian Ping, OSADA Yoshihito
    高分子学会予稿集 51 (1) 53 - 55 2002/05/10 [Not refereed][Not invited]
  • Go Kagata, Jian Ping Gong, Yoshihito Osada
    Journal of Physical Chemistry B 106 (18) 4596 - 4601 1089-5647 2002/05/09 [Refereed][Not invited]
     
    The velocity dependence of gel friction was investigated in pure water and in salt solutions to elucidate the effect of interracial interaction with substrates. When the gel and the substrate were repulsive, the frictional force depended strongly on the sliding velocity, whereupon the higher the normal compressive strain, the stronger the velocity dependence of the friction. The frictional force per unit area, f, was found to follow a power law as f ∝ vβ, where the exponent, β, depends on the normal compressive strain. This result shows that the gel friction in the repulsive case cannot be explained in terms of the simple hydrodynamic mechanism, from which f ∝ v1.0 is predicted. On the contrary, in the attractive case, the frictional force showed a maximum value with increase in the sliding velocity, which qualitatively coincides with our repulsion-adsorption model proposed previously.
  • Kaori Okawa, Jian Ping Gong, Yoshihito Osada
    Macromol. Rapid Commun. 23 (7) 423 - 425 1022-1336 2002/05 [Refereed][Not invited]
  • G Kagata, JP Gong, Y Osada
    JOURNAL OF PHYSICAL CHEMISTRY B 106 (18) 4596 - 4601 1520-6106 2002/05 [Refereed][Not invited]
     
    The velocity dependence of gel friction was investigated in pure water and in salt solutions to elucidate the effect of interfacial interaction with substrates. When the gel and the substrate were repulsive, the frictional force depended strongly on the sliding velocity, whereupon the higher the normal compressive strain, the stronger the velocity dependence of the friction. The frictional force per unit area,f, was found to follow a power law as f proportional to upsilon(beta), where the exponent, beta, depends on the normal compressive strain, This result shows that the gel friction in the repulsive case cannot be explained in terms of the simple hydrodynamic mechanism, from which f proportional to upsilon(1.0) is predicted. On the contrary, in the attractive case, the frictional force showed a maximum value with increase in the sliding velocity, which qualitatively coincides with our repulsion-adsorption model proposed previously.
  • Mao Peng, Takayuki Kurokawa, Jian Ping Gong, Yoshihito Osada, Qiang Zheng
    Journal of Physical Chemistry B 106 (12) 3073 - 3081 1089-5647 2002/03/28 [Refereed][Not invited]
     
    Theoretical analysis predicted that a gas layer is trapped between an aqueous solution and a rough hydrophobic substrate, and that the volume of the gas increases with the hydrophobicity and the surface roughness of the substrate. The heterogeneous structure formation of hydrogel on hydrophobic substrate is explained in terms of the retardation of the radical polymerization by residual oxygen trapped at the hydrophobic surface. The polymerization of 2-acrylamide-2-methyl' 1-propanesulfonic acid (AMPS) aqueous solution on Teflon substrate is experimentally studied by using a novel real time laser sheet refraction (RT-LSR) technique, and it is elucidated that residual oxygen in the trapped gas phase obviously retarded the polymerization of AMPS on the Teflon surface and lead to the formation of heterogeneous structure of the gel. The higher the oxygen concentration, the rougher the Teflon surface, the more significant of the substrate effect, which is in agreement with the theoretical prediction.
  • Gels stimulables (Intelligent gels)
    Hiroki Nagasawa, Jian Ping Gong, Yoshihito Osada
    Materiaux Adaptatifs (251) 175 - 181 2002/03 [Refereed][Invited]
  • H Nagasawa, JP Gong, Y Osada
    ACTUALITE CHIMIQUE (3) 175 - 181 0151-9093 2002/03 [Refereed][Not invited]
     
    A polymer gel is a soft and wet material capable of undergoing large deformation. A deformed gel in turn changes its chemical potential behaving as an energy transducer. Thus, a polymer gel shows a variety of stimuli-responsive actions responding outside environmental changes. In this article, unique electrical, thermal, chemical, and magnetic responses of polymer gels are described. The specific surface frictional property of gels is also briefly introduced.
  • JP Gong, Y Osada
    PROGRESS IN POLYMER SCIENCE 27 (1) 3 - 38 0079-6700 2002/02 [Not refereed][Invited]
     
    The sliding friction of various kinds of hydrogels on solid surfaces or on gels has been studied and it was found that the frictional behaviors of the hydrogels do not conform to Amonton's law F = muW, which well describes the friction of solids. The frictional force and its dependences on the load are quite different depending on the chemical structures of the gels, surface properties of the opposing surfaces, and the measurement condition. Additionally, the frictional coefficient la of the gel reaches a value as low as similar to 10(-3) which is much lower than those observed in solid materials. Theoretical analysis on the mechanism of the gel friction shows that the gel friction can be explained in terms of interfacial interaction, either attractive or repulsive, between the polymer chain and the solid surface. In the repulsive case, the friction is described in terms of the hydrodynamic lubrication of the solvent layer at the interface, which is formed due to the electrostatic repulsion of the two surfaces. For the attractive case, in addition to the hydrodynamic friction, the force to detach the adsorbing chain from the substrate appears as friction. The theoretical results coincide well with experimental observations that confirm the essential feature of the model. (C) 2001 Elsevier Science Ltd. All rights reserved.
  • L Chen, JP Gong, Y Osada
    MACROMOLECULAR RAPID COMMUNICATIONS 23 (3) 171 - 174 1022-1336 2002/02 [Refereed][Not invited]
     
    A novel thermosensitive interpenetrating network (IPN) hydrogel was prepared from an aqueous solution of poly[3,3-dimethyl(methacryloyloxyethyl)-propylammonium sulfonate] infiltrating a crosslinked sulfobetaine polymer, poly(2-acrylamido-2-methylpropylsulfonic acid). The IPN gel shows an upper critical solution temperature (UCST) depending on the molar ratio of the components and the presence of salt. In contrast to conventional gels, the IPN gel exhibits no volume phase transition after traversing the UCST.
  • T Miyazaki, T Kaneko, JP Gong, Y Osada, M Demura, M Suzuki
    LANGMUIR 18 (4) 965 - 967 0743-7463 2002/02 [Refereed][Not invited]
     
    We discovered that an amorphous-crystalline transition occurs when a small amount of water is introduced into an amphiphilic copolymer network consisting of n-alkyl acrylate (n = 14, 16, 18, 20, 22) and acrylic acid. Differential scanning calorimetry and X-ray diffraction studies show that the dry polymer network is in an amorphous state regardless of the presence of the crystalline moiety. By introduction of water to the polymer network, a crystalline structure attributed to the side-by-side packing of the alkyl chain is formed and the melting temperature of the crystalline increases with the amount of water and saturated to that of homo-n-alkyl acrylate polymers at a water content of 5 wt %. The mechanism of the water-induced amorphous-crystalline transition is explained in terms of enhanced mobility of the main chain due to hydration of the carboxyl groups of the polymer network.
  • 附柴裕之, 龔剣萍, 長田義仁
    日本バイオレオロジー学会誌(B&R) 16 (2) 51 - 60 2002 [Not refereed][Invited]
  • Yoshinori Katsuyama, Takayuki Kurokawa, Tatsuo Kaneko, Jian Ping Gong, Yoshihito Osada, Norishige Yotsukura, Taizo Motomura
    Macromolecular Bioscience 2 (4) 163 - 169 1616-5187 2002 [Refereed][Not invited]
     
    The inhibition of germination and development of zoospores originating from Laminaria angustata originated on various kinds of hydrogels is studied. The effects of the water content of the gel (the degree of swelling), the electrical nature (neutral, positive charge, negative charge), the charge density, the counterions of hydrogels on the inhibition of zoospore germination and development of gametophytes are phenomenologically investigated. Among the gels investigated, poly(acrylic acid) (PAA) gel showed a dramatic inhibition to germination, and might serve as a novel, environmentally safe inhibitor of zoospore adhesion. © Wiley-VCH Verlag GmbH, 69469 Weinheim 2002.
  • L Chen, T Kaneko, JP Gong, Y Osada, Y Ohsedo, Y Shirota
    MACROMOLECULAR CHEMISTRY AND PHYSICS 203 (1) 176 - 181 1022-1352 2002/01 [Refereed][Not invited]
     
    The water-soluble copolymers having pendant terthiophene, poly(AA3T-co-AA), were synthesized by radical copolymerization of [(2,2': 5', 2"-terthiophen-5-yl)methyl acrylate] (AA3T) and acrylic acid (AA), and their molecular structures and thermal behaviors were studied, X-ray diffraction study showed that the copolymers containing a certain amount of AA3T can form the crystals with monolayer structure, while incorporation of too many AA units into the copolymers disrupted this structure. Possible mechanism of self-doping on heating was discussed in terms of interaction between AA3T unit with AA unit in the copolymers.
  • Byoung-Suhk Kim, Hitoshi Fukuoka, Jian Ping Gong, Yoshihito Osada
    European Polymer Journal 37 (12) 2499 - 2503 0014-3057 2001/12 [Refereed][Not invited]
     
    The poly(3-thiopheneacetic acid) copolymers with 3-n-methylthiophene or with a 3-n-octadecylthiophene at the 3-position of a thiophene ring were synthesized. The solution and spectral properties of these hydrophobically modified polythiophenes have been studied by potentiometric titration, UV-visible spectroscopy. The effects of the rigid conjugated main chain, the steric hindrance and the hydrophobicity of a long alkyl side chain on the backbone conformational change have been discussed. We found that the conformational transition from the aggregate state to the extended state of the hydrophobically modified polythiophenes by the change of pH is sensitively restricted by the introduction of the hydrophobic alkyl or long alkyl side chains. © 2001 Elsevier Science Ltd. All rights reserved.
  • M. Peng, Jian Ping Gong, Y. Osada, X. Zhang, Q. Zheng
    Macromolecules 34 (22) 7829 - 7835 0024-9297 2001/11/23 [Refereed][Not invited]
     
    Real-time laser sheet refraction (RT-LSR) was used to study the polymerization kinetics of the hydrophilic monomer 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) in aqueous solution and the heterogeneity of the polymerization process on the surface of a Teflon substrate. The spatial distribution of refractive index along the vertical direction in the polymer solution was obtained in real time from the deflection of refracted light during polymerization. It was found that the polymerization of AMPS in the aqueous solution follows the first-order reaction mechanism. Inhomogeneous distribution of refractive index in the interface region near the Teflon surface, which results from the suppression of polymerization in the interface region, is also observed directly.
  • G Kagata, JP Gong, Y Osada
    WEAR 251 (1-12) 1188 - 1192 0043-1648 2001/10 [Refereed][Not invited]
     
    The friction between two chemically cross-linked polyelectrolyte gels carrying the same sign of charges has been investigated in pure water as well as in salt solutions. The friction was largely dependent on the charge densities of the gel surface and the ionic strength of the aqueous solution. The friction is described in terms of the hydrodynamic lubrication of the solvent layer between the two gel surfaces, which is formed due to the electrostatic repulsion of the two gel surfaces. The thickness of the solvent layer is estimated using the Poisson-Boltzmann equation supposing that the ionic osmotic pressure is balanced by the normal pressure applied on the gel. The friction values are calculated by considering the shear flow of solvent in the gel region using the Debye-Binkman equation. For strongly charged polyelectrolyte gels swollen in pure water, the theoretical analysis shows that the friction coefficient has almost no dependence on the water content of the gel, which agrees well with the experimental observations. (C) 2001 Elsevier Science B.V. All rights reserved.
  • JP Gong, G Kagata, Y Iwasaki, Y Osada
    WEAR 251 (1-12) 1183 - 1187 0043-1648 2001/10 [Refereed][Not invited]
     
    The sliding friction of various kinds of hydrogels has been studied and it was found that the frictional behaviors of the hydrogels do not conform to Amontons' law, F = muW, that well describes the friction of many solids. The frictional force and its dependencies of on load are quite different depending on the chemical structures of the gels, surface properties of the opposing substrates, and the measurement condition. The gel friction is explained in terms of interfacial interaction, either attractive or repulsive, between the polymer chain and the solid surface. According to this model, friction is ascribed to the viscous flow of solvent at the interface in the repulsive case. In the attractive case, the force to detach the adsorbing chain from the substrate appears as friction. Surface adhesion between glass particles and gels measured by AFM showed a good correlation with the friction, which support the repulsion-adsorption model proposed by the authors. (C) 2001 Elsevier Science B.V. All rights reserved.
  • Takashi Miyazaki, Tatsuo Kaneko, Jian Ping Gong, Yoshihito Osada
    Macromolecules 34 (17) 6024 - 6028 0024-9297 2001/08/14 [Refereed][Not invited]
     
    Two kinds of water-swollen hydrogels composed of three monomers-poly(stearyl acrylate (C18A)-co-n-alkyl acrylates (CnA)-co-acrylic acid (AA)) and poly(16-acryloyloxyhexadecanoic acid (AHA)-co-CnA-co-AA) (n is the number of carbon atoms of side chains: n = 14, 16, 18, 20, 22)-were synthesized, and their structures were investigated by wide-angle X-ray diffraction (WAXD) and small-angle X-ray diffraction (SAXD). Both gels formed the crystalline structure with the lamellae. In the case of poly(C18A-co-CnA-co-AA) gels, both the lamellar thickness, d2, and the melting temperature, Tm, increased with the increase in n, suggesting that C18A and CnA form molecularly mixed crystalline domains. On the other hand, d2 of poly(AHA-co-CnA-co-AA) gels was much smaller than that of poly(CnA-co-AA) gels, and Tm was constant regardless of n. An abrupt decrease in Tm was observed for poly(AHA-co-C18A-co-AA) gels at an AHA composition of 0.8. These results indicate that carboxyls attached at alkyl side chain end of AHA significantly shorten and stabilize the lamellae of the hydrogel due to the cooperative hydrogen bonding and rearrangement of the lamellar structure occurred.
  • Tetsuharu Narita, Alexandra Knaebel, Jean-Pierre Munch, Sanveur Jean Candau, Jian Ping Gong, Yoshihito Osada
    Macromolecules 34 (16) 5725 - 5726 0024-9297 2001/07/31 [Refereed][Not invited]
     
    The microrheological investigation of substrate-induced gradient structure in hydrogels was made. It was observed that hydrophobicity of the substrate perturbed the gelation process over a large spatial range. The crosslinking density of the gels decreased upon increasing the interface between the gel and the substrate. It was also accompanied by an increase in the structural inhomogeneties in the gel.
  • JP Gong, T Kurokawa, T Narita, G Kagata, Y Osada, G Nishimura, M Kinjo
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 123 (23) 5582 - 5583 0002-7863 2001/06 [Refereed][Not invited]
  • Akishige Kii, Jian Xu, Jian Ping Gong, Yoshihito Osada, Xianmin Zhang
    Journal of Physical Chemistry B 105 (20) 4565 - 4571 1089-5647 2001/05/24 [Refereed][Not invited]
     
    The substrate effect on the inhomogeneous gelation is in situ studied using various monomers: 2-acrylamide-2-methyl-1-propanesulfonic acid (AMPS), acrylic acid, and N,N′-dimethylacrylamide on various hydrophobic substrates with different surface tensions: poly(tetrafluoroethylene), polypropylene, polyethylene, polystyrene, and poly(vinyl chloride) in aqueous solution as well as in organic solvent by means of electronic speckle pattern interferometry. When the polymerization is carried out in water, a clear interface appears in the vicinity of the hydrophobic substrates at a critical time when the auto-acceleration of the polymerization starts. The polymerization on the hydrophobic substrate is suppressed after the appearance of the interface which gives rise to a heterogeneous gel structure. The thickness of the substrate-induced inhomogeneous layer increases with the square root of the polymerization time, showing the feature of monomer diffusion. An enhanced heterogeneous polymerization occurs on the hydrophobic substrate with a lower surface tension. These effects are greatly suppressed when the polymerization is carried out in ethanol and in the presence of hydrophobic monomer, giving rise to a homogeneous gelation. The correlation between the surface tension of the substrates and the interface strength in water suggests that the substrate-induced interface formation might be associated with the high interfacial tension between the substrate and the polymerizing solution.
  • J. P. Gong, A. Kii, J. Xu, Y. Hattori, Y. Osada
    J. Phys. Chem. B 105 (20) 4572 - 4576 1089-5647 2001/05 [Refereed][Not invited]
  • Kanji Yamaoka, Tatsuo Kaneko, Jian Ping Gong, Yoshihito Osada
    Macromolecules 34 (5) 1470 - 1476 0024-9297 2001/02/27 [Refereed][Not invited]
     
    Copolymers composed of various amounts of 4′-(11-acryloyloxyundecyloxy)biphenyl-4-carboxylic acid (11ABA) and acrylic acid (AA), poly(11ABA-co-AA)s, were synthesized, and their liquid crystalline structures were investigated both in dry and in water-swollen states. Wide- and small-angle X-ray studies revealed that both dry and swollen poly(11ABA-co-AA)s show a liquid crystalline structure, which transforms from smectic C with the bilayer (SmC2) to smectic C with the monolayer (SmC1), when the 11ABA composition, F([11ABA]/([11ABA]+[AA])), decreases from 0.72 to 0.44. The phase diagram of these copolymers was established by changing F and the temperature. It shows that the samples can build up a liquid crystalline structure for F as low as 0.07 at the elevated temperature of 155 °C. The enhanced ordering of the liquid crystalline structure and the thermostability of the copolymers were explained in terms of hydrogen bonding formed between carboxyls of mesogenic side chains and AA.
  • T. Narita, R. Ohtakeyama, M. Matsukata, J. P. Gong, Y. Osada
    Colloid Polym. Sci. 279 (2) 178 - 183 0303-402X 2001/02 [Refereed][Not invited]
  • 黒川孝幸, 龔剣萍, 長田義仁
    オレオサイエンス 1 (9) 929 - 934,926 1345-8949 2001 [Not refereed][Invited]
  • 高分子ゲルの表面摩擦特性 ─超低摩擦特性の開発─
    大垣伸介, 龔剣萍, 長田義仁
    バイオサイエンスとインダストリー 59 (12) 819 - 824 2001 [Not refereed][Invited]
  • 角五彰, 杉本信, 龔剣萍, 長田義仁
    表面技術 52 (4) 317 - 323 2001 [Not refereed][Invited]
  • ゲルの摩擦
    加々田剛, 龔剣萍, 長田義仁
    固体物理 36 (2) 103 - 111 2001 [Not refereed][Invited]
  • T. Mitsumata, J. P. Gong, Y. Osada
    Polym. Adv. Technol. 12 (1/2) 136 - 150 1042-7147 2001 [Not refereed][Invited]
  • JP Gong, G Kagata, Y Osada
    MACROMOLECULAR SYMPOSIA 159 215 - 220 1022-1360 2000/10 [Not refereed][Invited]
     
    The sliding friction of various kinds of hydrogels has been studied and it was found that the frictional behaviors of the hydrogels do not conform to Amonton's law F = muW, which well describes the friction of solids. The frictional force and its dependencies of on the load are quite different depending on the chemical structures of the gels, surface properties of the opposing substrates, and the measurement condition. The gel friction is explained in terms of interfacial interaction, either attractive or repulsive, between the polymer chain and the solid surface. According to this model, the frictional is ascribed to the viscous flow of solvent at the interface in the repulsive case. In the attractive case, the force to detach the adsorbing chain from the substrate appears as friction. Surface adhesion between glass particles and gels measured by AFM showed a good correlation with the friction, which support the repulsion-adsorption model proposed by authors.
  • A Matsuda, Y Katayama, T Kaneko, JP Gong, Y Osada
    JOURNAL OF MOLECULAR STRUCTURE 554 (1) 91 - 97 0022-2860 2000/10 [Refereed][Not invited]
     
    pH dependence of the structural change of the amphiphilic copolymer gels containing the crystallizable side chain with carboxylic end group, poly(16-acryloylhexadecanoic acid (AHA)-co-acrylic acid (AA)), has been investigated. The poly(AHA-co-AA) gels could maintain the crystalline domain of AHA units up to pH = 11 at ambient temperature, which abruptly transferred into disordered state beyond this pH due to the dissociation of the carboxylic group of AHA. However, the addition of salt or divalent ion enabled to crystallize the gel even at pH = 11.5 due to the effective shielding of the electrostatic repulsion. The mechanism of order-disorder transition through changes of pH and salt concentration was discussed in terms of association-dissociation of AHA groups. (C) 2000 Elsevier Science B.V. All rights reserved.
  • N Hirota, Y Kumaki, T Narita, JP Gong, Y Osada
    JOURNAL OF PHYSICAL CHEMISTRY B 104 (42) 9898 - 9903 1089-5647 2000/10 [Refereed][Not invited]
     
    To study the effect of charge on protein diffusion in hydrogels, mutual diffusion of a globular protein, myoglobin, has been investigated at various pH and ionic strength levels in two kinds of polysaccharide gels, neutral agarose gel and anionic carrageenan gel, by the recently developed electronic speckle pattern interferometry method. In the uncharged agarose gel, diffusions of myoglobin art: not effected by the change in pH and the ionic strength, indicating no electrostatic interaction between the gel and myoglobin. The experimental data in agarose gel agree with the combined model proposed by Clague and Philips for the diffusion of spheres in hydrogels. While in the negatively charged lambda -carrageenan gel, the diffusion of myoglobin is accelerated by electrostatic attraction when the pH is lower than the isoelectric point (pI) of the protein, but it is extensively hindered by the electrostatic repulsion when pH > pi. The diffusion of myoglobin in lambda -carrageenan gel agrees with the Tsai and Strieder model to give an apparent radius of the protein at various pH values.
  • T. Narita, R. Ohtakeyama, M. Nishino, J. P. Gong, Y. Osada
    Colloid Polym. Sci. 278 (9) 884 - 887 0303-402X 2000/09 [Refereed][Not invited]
  • Jian Ping Gong, Naoki Hirota, Akira Kakugo, Tetsuharu Narita, Yoshihito Osada
    J. Phys. Chem. B 104 (42) 9904 - 9908 1089-5647 2000/09 [Refereed][Not invited]
  • Tatsuo Kaneko, Kanji Yamaoka, Jian Ping Gong, Yoshihito Osada
    Macromolecules 33 (12) 4422 - 4426 0024-9297 2000/06/13 [Refereed][Not invited]
     
    The effects of water on the liquid crystalline structure of the copolymer poly(11-(4′-cyanobiphenyloxy)undecyl acrylate-co-acrylic acid)s (poly(11CBA-co-AA)s) were investigated. When the molar fraction of 11CBA, F, was higher than 0.26, the copolymers did not dissolve but swelled in water to give the hydrogels, keeping the smectic A ordering. This smectic A phase of the copolymers of F = 0.37 and 0.29 transferred to more organized smectic I ordering by further incorporation of water, while the SmA ordering of the copolymer of F = 0.26 disappeared to give the amorphous state. The role of water and the mechanism for forming a liquid crystalline structure in the hydrogel have been discussed.
  • BS Kim, L Chen, JP Gong, Y Osada
    KOREA POLYMER JOURNAL 8 (3) 116 - 119 1225-5947 2000/06 [Refereed][Not invited]
     
    The doping behaviors of water-soluble poly(3-thiopheneacetic acid) (P3TAA) and its gel using I-2 and concentrated HClO4 aqueous solutions were investigated by UV-Visible absorption spectrometer. Electrical conductivity of the doped polythiophene gel was also studied. I-doping of water-soluble P3TAA gave rise to a new broad polaron peak at around 749 nm, which corresponds to localization of electron. It was found that doping ability of P3TAA gel was strikingly dependent on the concentration of HClO solution.
  • JP Gong, G Kagata, Y Iwasaki, Y Osada
    CHINESE JOURNAL OF POLYMER SCIENCE 18 (3) 271 - 275 0256-7679 2000/05 [Not refereed][Invited]
     
    The sliding friction of various kinds of hydrogels has been studied and it was Found that the frictional behaviors of the hydrogels do not conform to Amonton's law F = mu W which well describes the friction of solids. The frictional force and its dependence on the load are quite different depending on the chemical structures of the gels, surface properties of the opposing substrates, and the measurement condition. The gel friction is explained in terms of interfacial interaction, either attractive or repulsive, between the polymer chain and the solid surface. According to this model, the friction is ascribed to the viscous flow of solvent at the interface in the repulsive case. In the attractive case, the force to detach the adsorbing chain from the substrate appears as friction. The surface adhesion between glass particles and gels measured by AFM showed a good correlation with the friction, which supported the repulsion-adsorption model proposed by the authors.
  • Atsushi Matsuda, Tatsuo Kaneko, Jianping Gong, Yoshihito Osada
    Macromolecules 33 (7) 2535 - 2538 0024-9297 2000/04/04 [Refereed][Not invited]
     
    Moderately water-swollen hydrogels were prepared by copolymerizing n-stearyl acrylate (SA), 2,2,2-trifluoroethyl acrylate (TFEA), and acrylic acid (AA), and the effects of water and TFEA on the molecular and supramolecular structure were investigated. An incorporation of TFEA brought about a decreased d2 spacing (long-range ordering) presumably due to a local render amorphous while d1 (short-range ordering) was kept constant. Enhanced effects of water and stretching on the supramolecular organization were demonstrated. The transition temperature at which Young's modulus abruptly changes could be controlled by changing the TFEA content of the gel.
  • J. P. Gong, Y. Iwasaki, Y. Osada
    J. Phys. Chem. B 104 (15) 3423 - 3428 1089-5647 2000/03 [Refereed][Not invited]
  • ゲル運動素子によるケミカルモーター
    龔剣萍, 長田義仁
    化学と工業 53 (2) 184 - 187 2000 [Not refereed][Invited]
  • Surface Dynamic Friction of Polymer Gels
    P. Gong, Go Kagata, Y. Osada
    Reports on Progress in Polymer Physics in Japan 43 141 - 162 0486-4476 2000 [Not refereed][Invited]
  • T. Miyazaki, K. Yamaoka, T. Kaneko, J. P. Gong, Y. Osada
    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 1 (4) 201 - 210 1468-6996 2000 [Not refereed][Invited]
     
    A water-swollen hydrogel with a molecularly-ordered structure was prepared by copolymerizing acrylic acid and acrylic monomer containing hydrophobic long alkyl or mesogenic moiety. The gels with a long alkyl side chain formed the crystalline structure and undergo the reversible order disorder transition with change in temperature or solvent composition which accompanied a dramatic change in Young's modulus. These gels exhibited such chemomechanical behaviors as the shape memory and the rotational motility on the water surface. On the other hand, the gels with the mesogenic side chain formed the liquid crystalline structure with polymorphism in water, and mesophase diagram was established by changing copolymer composition and water content. Mechanism of these structural and chemomechanical behaviors has been explained in terms of order disorder transition. (C) 2001 Published by Elsevier Science Ltd.
  • D. Szab?, S. Akiyoshi, T. Matsunaga, J. P. Gong, Y. Osada, M. Zrinyi
    J. Chem. Phys. 113 (18) 8253 - 8259 0021-9606 2000 [Refereed][Not invited]
  • Tetsuharu Narita, Aki Hirai, Jian Xu, Jian Ping Gong, Yoshihito Osada
    Biomacromolecules 1 (2) 162 - 167 1525-7797 2000 [Refereed][Not invited]
     
    Substrate effects of hydrogel surfaces prepared on hydrophilic and hydrophobic substrates on the cell adhesion and disruption were studied. The adhesion of tobacco protoplasts onto anionic hydrogels was strongly influenced by the substrates on which the gels were synthesized. In the case of anionic poly(2-acrylamido-2-methylpropanesulfonic acid) gel, more cells adhered on the gel surface prepared on hydrophobic substrates than that prepared on hydrophilic substrates. On the other hand, in the case of cationic quaternized poly(dimethylaminopropylacrylamide) gel, cell disruption occurred in a few seconds accompanied with an intensive release of cellular contents on the gel surface prepared on the hydrophilic substrates, while the cationic gel synthesized on hydrophobic substrates induced no cell disruption. These different behaviors of the cell have been made in terms of different structures of gel surfaces associated with the presence of flexible dangling chains.
  • L. Chen, Y. Honma, T. Mizutani, D. J. Liaw, J. P. Gong, Y. Osada
    Polymer 41 (1) 141 - 147 0032-3861 2000/01 [Refereed][Not invited]
     
    A zwitterionic polymer - poly-3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate (PDMAPS) - was synthesized and its complexation behaviors with polyanion: poly-2-acrylamido-2-methyl propane sulfonic acid (PAMPS) and polycation: poly-3-acryloylamino propyl trimethyl ammonium chloride (PDMAPAA-Q) or: x,y-ionene bromides (x = 3,6 y = 3,4) have been studied. One of the characteristic features of these complexes is that they are soluble, in spite of the abolishment of positive or negative charge of PDMAPS after the complexation and is able to exhibit UCST depending on the concentration and the mixing molar ratio. It was found that PDMAPS-PAMPS complex dramatically increases the viscosity to give a network structure through electrostatic interaction extensively decreasing the UCST, while the PDMAPS-polycation complex first decreases, but then increases the UCST without forming the network. The mechanism of different behaviors of these complexes has been discussed.
  • T Kaneko, K Yamaoka, JP Gong, Y Osada
    MACROMOLECULES 33 (2) 412 - 418 0024-9297 2000/01 [Refereed][Not invited]
     
    Copolymers composed of 11-(4'-cyanobiphenyloxy)undecyl acrylate (11CBA) and acrylic acid (AA), poly(11CBA-co-AA)s, were prepared by changing their molar ratio, and their structures were investigated under various temperatures. From wide- and small-angle X-ray studies, it was found that poly(11CBA) and poly(11CBA-co-AA)s with a mole fraction of 11CBA more than 0.26 showed the smectic A (SmA) phase with a layer spacing (d(2)) of 46-58 Angstrom, to which the mesogenic moiety of 11CBA attached perpendicularly with a side-by-side spacing of 4.3 Angstrom (d(1)). The ordering as well as the d(2) spacing of the smectic layer increased by incorporating an appropriate amount of AA. At the same time, the isotropic temperature of the copolymer increased with AA content. The enhanced ordering and the thermostability by introducing AA were explained in terms of the cooperative hydrogen interaction between the carboxylic groups of AA.
  • Li Chen, ByoungSuhk Kim, Masahiko Nishino, Jian Ping Gong, Yoshihito Osada
    Macromolecules 33 (4) 1232 - 1236 0024-9297 2000 [Refereed][Not invited]
     
    A chemically cross-linked and water-swollen poly(3-thiopheneacetic acid) (P3TAA) gel was synthesized, and its swelling and spectral changes associated with its ionization were studied. The gel undergoes an abrupt red shift in the electronic spectra at a certain pH, suggesting that a conformational transition due to ionization occurred despite the chemical cross-linkage. By changing the solvent composition, during cross-linking, gels with an enhanced π conjugated structure were prepared. By doping of P3TAA gel with a HClO4 solution, a satisfactorily high electrical conductivity was obtained.
  • Jian Ping Gong, Go Kagata, Yoshihito Osada
    Macromolecular Symposia 159 123 - 130 1022-1360 2000 [Refereed][Not invited]
     
    The fracture toughness between polystyrene (PS)/ poly(methyl methacrylate) (PMMA) reinforced with reactive polymers, poly(glycidyl methacrylate) (PGMA) and dicarboxy or monocarboxy terminated PS (dcPS and mcPS), was measured by the asymmetric fracture test. Molecular weight effect of mcPS, although the molecular weight distribution is rather polydisperse, on the maximum achievable fracture toughness, Gmax qualitatively agreed with the results of the monodisperse case4.5). In the case of dcPS with Mw≅ 142 K, Gmax reached ca. 170 J/m2 which is nearly 8 times higher than that of mcPS of molecular weight of about 150K. From the mechanical point of view, dcPS with a degree of polymerization (N) greater than the ratio of chain breaking force to monomeric friction force (fb/fmono) is more effective in enhancing the interfacial adhesion than mcPS since it provides two stitches to the interface. It was also shown by Monte Carlo simulation on reactive polymer system that the di-endfunctional polymers are more effective than mono-endfunctional polymers in reinforcing the week interface between immiscible polymers.
  • Y Osada, JP Gong, T Narita
    MATERIALS OF SMART SYSTEMS III 604 149 - 159 0272-9172 2000 [Refereed][Not invited]
     
    We reported an electro-driven chemomechanical hydrogel showing quick responses with worm-like motility. The principle of the motion is based on the molecular assembly reaction of cationic surfactant and negatively charged hydrogel. And direction of complexation accompanying gel contraction is controlled by changing the polarity of the applied electric field. Both thermodynamics and kinetics of surfactant binding and diffusion are investigated experimentally and theoretically. We also reported shape memory hydrogel by order-disorder transition of alkyl side chain, and some examples od friction of hydrogels showing that frictional behaviors of hydorgels do not conform to Amonton's law.
  • BS Kim, L Chen, JP Gong, Y Osada
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS 349 335 - 338 1058-725X 2000 [Refereed][Not invited]
     
    The water-swollen poly(3-thiopheneacetic acid) (P3TAA) gels with various degree of cross-linkage (DCL) were synthesized. Doping behaviors of watersoluble polythiophene and its gel using I-2 and concentrated HClO4 solution as dopants were studied. Electrical conductivity of doped polythiophene gel was investigated. Tn addition, we have investigated chemomechanical behavior by electric field, and the possibility of polythiophene gel as an electrode is introduced.
  • GB Park, Y Kagami, JP Gong, DC Lee, Y Osada
    THIN SOLID FILMS 350 (1-2) 289 - 294 0040-6090 1999/08 [Refereed][Not invited]
     
    An ionizable thin film with gradient network size in direction of thickness was prepared using 10-undecenoic acid(UA) by plasma polymerization. Gradient structure in the network size was estimated by values of relative diffusion coefficient of ferocian ions through the film. The obtained film was found to show chemomechanical behavior. The film bent in alkaline solution due to anisotropic swelling in direction of thickness and recovered to the original shape in acid solution. (C) 1999 Elsevier Science S.A. All rights reserved.
  • T Kaneko, S Orita, JP Gong, Y Osada
    LANGMUIR 15 (17) 5670 - 5675 0743-7463 1999/08 [Refereed][Not invited]
     
    The complexation and crystallization of the tetrasodium salt of copper tetrasulfophthalocyanine (CuTSPc) with the solvated polycations poly((acryloyloxy)ethylpyridinium bromide) (PC2py) and poly((acryloyloxy)dodecylpyridinium bromide) (PC12py) and their gels were studied. CuTSPc binds to PC2py cooperatively and stoichiometrically, while it binds to PC12py in a cooperative but nonstoichiometric way. The wide-angle X-ray diffraction (WAXD) pattern of the CuTSPc-PC12py complex showed high crystallinity, in which the CuTSPc molecules formed hexagonal columns. On the other hand, diffraction peaks were weaker in the WAXD pattern of the CuTSPc-PC2py complex. The longer side chain of the polycations gives the bound CuTSPc molecules sufficient mobility and space to form better organized crystals. The complex of the CuTSPc-PC12py gel also crystallized despite the low mobility of the side chain since the main chain is restrained by cross-linkages.
  • T. Narita, N. Hirota, J. P. Gong, Y. Osada
    J. Phys. Chem. B 103 (30) 6262 - 6266 1089-5647 1999/07 [Refereed][Not invited]
  • X. M. Zhang, N. Hirota, T. Narita, J. P. Gong, Y. Osada, K. S. Chen
    J. Phys. Chem. B 103 (29) 6069 - 6074 1089-5647 1999/07 [Refereed][Not invited]
  • J. P. Gong, G. Kagata, Y. Osada
    J. Phys. Chem. B 103 (29) 6007 - 6014 1089-5647 1999/07 [Refereed][Not invited]
  • Byoungsuhk Kim, Li Chen, Jianping Gong, Yoshihito Osada
    Macromolecules 32 (12) 3964 - 3969 0024-9297 1999/06/15 [Refereed][Not invited]
     
    Water-soluble poly(3-thiophene acetic acid) (P3TAA) and its copolymers with 3-n-methylthiophene or with 3-n-octadecylthiophene were synthesized. The solution properties of these water-soluble polythiophene carboxylic acids were studied by potentiometric titration, viscosity measurements, and UV-visible spectroscopy. We have found that the Henderson-Hasselbach plot of the titration curve showed an inflection of the slope around pH = 5-6. The reduced viscosity and electronic spectra of the P3TAA aqueous solution also showed an abrupt change at this pH region. These results are quite different from that of a common flexible polyelectrolyte, such as poly(acrylic acid) (PAA) and strongly suggest that the pH-induced abrupt conformational changes occurred from the aggregated state to the extended state of the polymer main chain. The observed results are explained in terms of the rigid hydrophobic main chain and the nature of the conjugated polymer.
  • JP Gong, Y Iwasaki, G Kagata, Y Osada
    PROCEEDINGS OF THE JAPAN ACADEMY SERIES B-PHYSICAL AND BIOLOGICAL SCIENCES 75 (6) 122 - 126 0386-2208 1999/06 [Not refereed][Invited]
     
    The sliding fiction of various kinds of hydrogels has been studied and it was found that the frictional behaviors of the hydrogels do not conform to Amonton's law F = mu W, which well describes the friction of solids. The frictional force and its dependencies on the load are quite different depending on the chemical structures of the gels, surface properties of the opposing substrates, and the measurement condition. The gel friction is explained in terms of interfacial interaction, either attractive or repulsive, between the polymer chain and the solid surface. According to this model, the frictional force is ascribed to the viscous flow of solvent at the interface in the repulsive case. In the attractive case, the force to detach the adsorbing chain from the substrate appears as friction. Surface adhesion between glass particles and gels measured by AFM showed a good correlation with the friction, which support the repulsion-adsorption model proposed by authors.
  • T. Mitsumata, K. Ikeda, J. P. Gong, Y. Osada, Denes Szabo, Miklos Zrinyi
    J. Appl. Phys. 85 (12) 8451 - 8455 0021-8979 1999/06 [Refereed][Not invited]
  • J. P. Gong, Y. Iwasaki, Y. Osada, K. Kurihara, Y. Hamai
    J. Phys. Chem. B 103 (29) 6001 - 6006 1089-5647 1999/05 [Refereed][Not invited]
  • M Matsukata, M Nishino, JP Gong, Y Osada, Y Sakurai, T Okano
    COLLOIDS AND SURFACES B-BIOINTERFACES 13 (4) 203 - 211 0927-7765 1999/05 [Refereed][Not invited]
     
    Interaction between protein and cell was discussed using bovine serum albumin (BSA) and yeast protoplast. Glutaraldehyde was used for crosslinking intracellular and intrinsic membrane proteins, which enabled experiments to be carried under various conditions such as pH, salt, and temperature. BSA bound to the surface of yeast protoplast mainly due to the electrostatic interaction, which was determined by investigating the surface potential of the protoplast and the binding isotherms at various pHs. The BSA binding demonstrated the modified Langmuir type and the binding constants and cooperativity parameters were calculated. At the isoelectric point of both BSA and protoplast, the amount of binding obtained the maximum, while at lower and higher pH the binding was significantly decreased. The binding was further discussed in terms of lipid fluidity of the protoplast. (C) 1999 Elsevier Science B.V. All rights reserved.
  • X. M. Zhang, J. Xu, K. Okawa, Y. Katsuyama, J. P. Gong, Y. Osada, K. S. Chen
    J. Phys. Chem. B 103 (15) 2888 - 2891 1089-5647 1999/03 [Refereed][Not invited]
  • Byoungsuhk Kim, Motoki Ishizawa, Jianping Gong, Yoshihito Osada
    J. Polym. Sci.: Part A: Polym. Chem. 37 (5) 635 - 644 0887-624X 1999/03 [Refereed][Not invited]
  • 双性イオン高分子と高分子電解質との相互作用によるUCST制御
    陳莉, 龔剣萍, 長田義仁
    高分子加工別冊 48 (11) 500 - 505 1999 [Not refereed][Invited]
  • 加々田剛, 龔剣萍, 長田義仁
    ネットワークポリマー 20 (3) 130 - 137 1342-0577 1999 [Not refereed][Invited]
  • 生物はなぜ滑らかに動けるのか
    龔剣萍, 長田義仁
    科学 69 (8) 672 - 680 1999 [Not refereed][Invited]
  • 高分子ゲル-界面活性剤相互作用のダイナミックス
    成田哲治, 龔剣萍, 長田義仁
    高分子加工 48 (6) 268 - 274 1999 [Not refereed][Invited]
  • 秩序-無秩序転移するハイドロゲル─その形状記憶特性と運動特性─
    龔剣萍, 長田義仁
    機能材料 19 (3) 5 - 12 1999 [Not refereed][Invited]
  • ByoungSuhk Kim, Jianping Gong, Yoshihito Osada
    Polymer International 48 (8) 691 - 698 0959-8103 1999 [Not refereed][Invited]
     
    Surfactant binding and molecular assembly reactions of solvated and weakly cross-linked polyelectrolytes having charges on the side chain and on the backbone have been studied using various kinds of oppositely charged surfactants. We have found that there are three categories of surfactant binding: they are cooperative and stoichiometric, non-cooperative and stoichiometric, and cooperative and non-stoichiometric. The modes of these categories are predominantly determined by the steric chemical structure of the surfactant, hydrophobicity and charge densities of the polyelectrolytes. The mechanism of complex formation and the structure formation are discussed. A water-swollen polymer gel which swings and undulates water backwards was made by applying an electric field and making a reversible assembly-reaction of surfactant on the gel. Using this principle, a fish-like soft-machine was made which slowly moves forwards by undulating its tail. The motion is analysed and the mechanism is discussed. © 1999 Society of Chemical Industry.
  • Y. Osada, J. P. Gong
    Advanced Materials 10 (11) 827 - 837 0935-9648 1999/01 [Not refereed][Invited]
  • N Isogai, T Narita, L Chen, M Hirata, JP Gong, Y Osada
    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 147 (1-2) 189 - 201 0927-7757 1999/01 [Refereed][Not invited]
     
    Surfactant bindings with solvated and crosslinked polyelectrolytes having charges on the side chain as well as chain backbone have been studied using various kinds of oppositely charged surfactants. We have found that there are three categories of the surfactant binding: they are cooperative and stoichiometric, non-cooperative and stoichiometric and cooperative and non-stoichiometric. The modes of these categories are predominantly determined by the steric chemical structure of the surfactant, hydrophobicity and the charge densities of the polyelectrolytes. Process and mechanism of the surfactant binding have been discussed. (C) 1999 Elsevier Science B.V. All rights reserved.
  • DJ Liaw, BY Liaw, JP Gong, Y Osada
    SYNTHETIC METALS 99 (1) 53 - 59 0379-6779 1999/01 [Refereed][Not invited]
     
    The brittle property of poly(3-thiopheneacetic acid) film has been rectified via network formation, as derived from electropolymerization of 3-thiopheneacetic acid with 3,3'-bithiophene or hexamethylene diisocyanate-bithiophene, without losing its conductivity and self-doping property. Solvent swelling behaviors of poly(3-thiophene acetic acid) and its network films rely on the film composition and solvent. The network film crosslinked by 3,3'-bithiophene exhibits a drastic volume change when the temperature exceeds 100 degrees C. The passivation mechanism proposed here explains the electrical conductivity's decrease and the LR spectra's changes after iodine doping. (C) 1999 Elsevier Science S.A. All rights reserved.
  • JP Gong, Y Iwasaki, G Kagata, Y Osada
    SMART STRUCTURES AND MATERIALS 1999: ELECTROACTIVE POLYMER ACTUATORS AND DEVICES 3669 218 - 225 0277-786X 1999 [Refereed][Not invited]
     
    The sliding friction of various kinds of hydrogels has been studied and it was found that the frictional behaviors of the hydrogels do not conform to Amonton's law F = mu W, which well describes the friction of solids. The frictional force and its dependencies of on the load are quite different depending on the chemical structures of the gels, surface properties of the opposing substrates, and the measurement condition. The gel friction is explained in terms of interfacial interaction, either attractive or repulsive, between the polymer chain and the solid surface. According to this model, the frictional is ascribed to the viscous flow of solvent at the interface in the repulsive case. In the attractive case, the force to detach the adsorbing chain from the substrate appears as friction. Surface adhesion between glass particles and gels measured by AFM showed a good correlation with the friction, which support the repulsion-adsorption model proposed by authors.
  • T Narita, JP Gong, Y Osada
    SMART STRUCTURES AND MATERIALS 1999: ELECTROACTIVE POLYMER ACTUATORS AND DEVICES 3669 264 - 271 0277-786X 1999 [Refereed][Not invited]
     
    A weakly crosslinked poly(2-acrylamido-2-metbylpropanesulfonic acid) immersed in cationic surfactant (N-n-alkylpyridinium chloride) shows biomimetic chemomechanical movement under de current. The principle of the movement is based on an electrokinetic molecular assembly reaction of the surfactant onto the polymer network. In order to analyze the diffusion and binding processes which are both of importance for understanding the alkyl size dependence of the chemomechanical behavior, kinetic studies of the surfactants binding were made systematically changing the alkyl size and concentration of the surfactants and ionic strengh It was found that the driving force of the surfactant diffusion is the electrochemical potential gradient, while the surfactant binding enhances the diffusion process. A mathematical model for the surfactant diffusion was developed taking account of the surfactant binding process and obtained results were well explained the experimental observations.
  • Y Osada, JP Gong
    SMART STRUCTURES AND MATERIALS 1999: ELECTROACTIVE POLYMER ACTUATORS AND DEVICES 3669 12 - 18 0277-786X 1999 [Refereed][Not invited]
  • Tatsuo Kaneko, Takashi Miyazaki, Kanji Yamaoka, Yuichi Katayama, Atsushi Matsuda, Jian Ping Gong, Yoshihito Osada
    Proceedings of SPIE - The International Society for Optical Engineering 3669 199 - 208 0277-786X 1999/01/01 [Not refereed][Not invited]
     
    The shape memory effect with multi stimuli responses of the hydrogels having the various type of long alkyl chains: poly (stearyl acrylate -co- acrylic acid) p(HA-co-AA), poly(16-acryloylhexadecanoic acid -co- acrylic acid) p(AHA-co-AA), poly(12-acryloyldodecanoic acid -co- acrylic acid) p(ADA-co-AA), and poly (stearyl acrylate -co- methyl acrylate) p(SA-co-MA) were investigated. P(SA-co-AA) gel exhibited the reversible order-disorder transition on heating at 49 °C and on cooling at 42 °C. The transition was derived from the melting of the hydrophobic domain formed by the long alkyl side chain. The Young's modulus decreased dramatically during the transition. Besides this gel showed the shape memory effect based on the order-disorder transition. The shape of deformed p(SA-co-AA) gel recovered very quickly (5s). In the p(SA-co-MA)gel system, the transition temperature could be varied. Moreover, p(AHA-co-AA) gel responded to not only temperature change but also change of pH and solvent composition.
  • J. P. Gong, Y. Osada
    J. Chem. Phys. 109 (18) 8062 - 8068 0021-9606 1998/11 [Refereed][Not invited]
  • T Mitsumata, K Ikeda, JP Gong, Y Osada
    APPLIED PHYSICS LETTERS 73 (16) 2366 - 2368 0003-6951 1998/10 [Refereed][Not invited]
     
    A solvent-driven chemical motor using amphiphilic polymer gel has been fabricated. The driving force of the gel originates from the surface tension of spreading organic fluid which is pumped out by osmotic and hydrostatic pressures in the gel. A tetrahydrofurane-swollen gel equipped with a spouting hole made a controlled translational motion with a velocity of 77 mm/s or rotational motion with a maximum speed of 400 rpm and a torque of 10(-9)-10(-7) Nm on the water surface. A generator to produce an electric power with a maximum electromotive force of 15 mV and electric power of 0.2 mu W has also been constructed. The successful fabrication of gel motor may produce a new era of soft machine systems which work without pollution and unnecessary intermediates. (C) 1998 American Institute of Physics. [S0003-6951(98)02642-4].
  • Tetsu Mitsumata, Jian Ping Gong, Kazuo Ikeda, Yoshihito Osada
    J. Phys. Chem. B 102 (27) 5246 - 5251 1089-5647 1998/06 [Refereed][Not invited]
  • Tetsu Mitsumata, Jian Ping Gong, Kazuo Ikeda, Yoshihito Osada
    J. Phys. Chem. B 102 (23) 4566 - 4572 1089-5647 1998/05 [Refereed][Not invited]
  • Atsushi Matsuda, Jian Ping Gong, Yoshihito Osada
    Polymer Gels and Networks 6 (5) 307 - 317 0966-7822 1998/04 [Refereed][Not invited]
  • Li Chen, Shuyan Yu, Yoshiharu Kagami, Jianping Gong, Yoshihito Osada
    Macromolecules 31 (3) 787 - 794 0024-9297 1998/02/10 [Refereed][Not invited]
     
    Studies on the interaction between polycations carrying charges on the chain backbone [x,y-ionene bromides (x = 3, 6, 12 y = 3, 4, 6, 12)] and anionic surfactants (sodium alkyl sulfates and sodium alkanesulfonates) have been made in water. It was found that there are two categories of surfactant binding: one is the formation of insoluble complex with one-to-one composition and the other is that of soluble complex with nonstoichiometric composition. Some of these complexes have ordered structure on a molecular and a supramolecular level, wherein the charge density and the alkyl size separating the charges on the chain backbone play an important role. The mechanism and process of the complex formation have been discussed.
  • M Nishino, JP Gong, Y Osada
    BIOSEPARATION 7 (4-5) 269 - 280 0923-179X 1998 [Not refereed][Invited]
  • T Narita, JP Gong, Y Osada
    WILEY POLYMER NETWORKS GROUP REVIEW SERIES, VOL 1 - CHEMICAL AND PHYSICAL NETWORKS 1 477 - 488 1998 [Not refereed][Invited]
     
    The cooperative binding of a Linear as well as a crosslinked polyelectrolyte with an oppositely charged surfactant has been analyzed experimentally and theoretically. The experimental results showed that the presence of crosslinkage significantly enhances the initiation process but strongly suppresses the cooperativity of the binding. In the theoretical analysis, the hydrophobic interaction has been treated using the nearest neighbour interaction model, while the electrostatic interaction has been calculated using the rod-like model. The general formulas derived on the basis of the free energy minimum principle demonstrated that the crosslinkage enhances the initiation process but strongly suppresses the cooperativity due to the osmotic pressure in the network domain. The theoretical results showed fairly good agreement with the experimental data, confirming the essential features of the theory.
  • M. Matsukata, M. Hirata, J. P. Gong, Y. Osada, Y. Sakurai, T. Okano
    Colloid Polymer Sci. 276 (1) 11 - 18 0303-402X 1998/01 [Refereed][Not invited]
  • T. Narita, J. P. Gong, Y. Osada
    Macromol. Rapid Commun. 18 (9) 853 - 857 1022-1336 1997/09 [Refereed][Not invited]
  • J. P. Gong, M. Higa, Y. Iwasaki, Y. Katsuyama, Y. Osada
    J. Phys. Chem. B 101 (28) 5487 - 5489 1997/07 [Refereed][Not invited]
  • Y Ueoka, J Gong, Y Osada
    JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES 8 (5) 465 - 471 1045-389X 1997/05 [Refereed][Not invited]
     
    A water-swollen polymer gel which swings and undulates water backward was made by applying an electric field and making a reversible assembly-reaction of surfactant on the gel. Using this principle a fish-like soft-machine slowly moving forward by undulating the tail was made. The motion was analyzed and the mechanism was discussed.
  • J. P. Gong, N. Komatsu, T. Nitta, Y. Osada
    J. Phys. Chem. B 101 (5) 740 - 745 1089-5647 1997/01 [Refereed][Not invited]
  • SY Yu, M Hirata, L Chen, S Matsumoto, M Matsukata, JP Gong, Y Osada
    MACROMOLECULES 29 (24) 8021 - 8023 0024-9297 1996/11 [Refereed][Not invited]
  • JP Gong, T Mizutani, Y Osada
    POLYMERS FOR ADVANCED TECHNOLOGIES 7 (10) 797 - 804 1042-7147 1996/10 [Refereed][Not invited]
     
    The cooperative binding of a linear as well as a crosslinked polyelectrolyte with an oppositely charged surfactant has been analyzed theoretically and experimentally. The experimental results showed that the presence of crosslinkage significantly enhances the initiation process but strongly suppresses the cooperation of the binding. In the theoretical analysis, the hydrophobic interaction has been treated using the nearest-neighbor interaction model, while the electrostatic interaction has been calculated using a rodlike model. The general formulas derived on the basis of the free energy minimum principle demonstrated that the crosslinkage enhances the initiation process but strongly suppresses the cooperation owing to the osmotic pressure in the network domain. The theoretical results showed fairly good agreement with the experimental data, confirming the essential features of the theory.
  • N Isogai, JP Gong, Y Osada
    MACROMOLECULES 29 (21) 6803 - 6806 0024-9297 1996/10 [Refereed][Not invited]
     
    A discontinuous volume collapse occurs on binding of tetraphenylphosphonium chloride (TPPC) to the anionic polyelectrolyte network poly[2-(acrylamido)-2-methylpropanesulfonic acid] (PAMPS) gel. The amount of TPPC inducing volume collapse decreases with increasing temperature. The TPPC binding to the gel is noncooperative and insensitive to temperature change in spite of the strong hydrophobic interaction of TPPC. The mechanism of the TPPC binding is discussed.
  • Y. Kagami, J. P. Gong, Y. Osada
    Macromol. Rapid Commun. 17 (8) 539 - 543 1022-1336 1996/08 [Refereed][Not invited]
  • J. P. Gong, S. Matsumoto, M. Uchida, N. Isogai, Y. Osada
    J. Phys. Chem. 100 (26) 11092 - 11097 0022-3654 1996/06 [Refereed][Not invited]
  • Y Osada, JP Gong
    ADVANCED BIOMATERIALS IN BIOMEDICAL ENGINEERING AND DRUG DELIVERY SYSTEMS 8 - 12 1996 [Refereed][Not invited]
  • Y Osada, Y Ueoka, JP Gong
    THIRD INTERNATIONAL CONFERENCE ON INTELLIGENT MATERIALS - THIRD EUROPEAN CONFERENCE ON SMART STRUCTURES AND MATERIALS 2779 344 - 348 1996 [Refereed][Not invited]
  • S Matsumoto, JP Gong, Y Osada
    THIRD INTERNATIONAL CONFERENCE ON INTELLIGENT MATERIALS - THIRD EUROPEAN CONFERENCE ON SMART STRUCTURES AND MATERIALS 2779 349 - 352 1996 [Refereed][Not invited]
  • XM Zhang, KS Chen, XQ Zhou, Y Kagami, GB Park, JP Gong, Y Osada
    OPTICAL RECORDING, STORAGE, AND RETRIEVAL SYSTEMS 2890 136 - 139 1996 [Refereed][Not invited]
  • JP GONG, Y OSADA
    ELECTROCHIMICA ACTA 40 (13-14) 2445 - 2447 0013-4686 1995/10 [Refereed][Not invited]
     
    The electrostatic potential energy distribution of polyelectrolyte gels has been modelled and simulated on the basis of Poisson-Boltzmann equation. The simulation was carried out with a three dimensional network model. The simulation reveals that there exist deep electrostatic potential wells at every crosslinking point and potential valleys around the polymer chains. The simulation results also indicated that a strong electrostatic field exists near the polymer chains especially around the crosslinking points. Various abnormal phenomena observed in the polymer gel, such as the presence of non-frozen water, higher electroconductivity at low temperature, electrocontractile behavior, etc., are considered to be associated with the presence of this strong electric field.
  • Kiyoshi Sawahata, Jian Ping Gong, Yoshihoto Osada
    Macromol. Rapid Commun. 16 (10) 713 - 716 1022-1336 1995/10 [Refereed][Not invited]
  • J. P. Gong, Y. Osada
    J. Phys. Chem. 99 (27) 10971 - 10975 0022-3654 1995/07 [Refereed][Not invited]
  • JP GONG, Y OSADA
    CHEMISTRY LETTERS (6) 449 - 450 0366-7022 1995/06 [Refereed][Not invited]
     
    The electrostatic potential distribution of cross-linked polyelectrolyte gels has been numerically calculated on the base of Poisson-Boltzmann equation using a three dimensional network geometry. The simulational result revealed that besides potential energy valleys around the polymer chains, there should exist deep electrostatic potential energy wells at every crosslinking point.
  • Y. Osada, J. P. Gong, M. Uchida, N. Isogai
    Japanese Journal of Applied Physics 34 (4B) L511 - L512 0021-4922 1995/04 [Refereed][Not invited]
  • T NISHIDE, JP GONG, H YASUNAGA, N NISHI, Y OSADA
    MACROMOLECULES 27 (26) 7877 - 7879 0024-9297 1994/12 [Refereed][Not invited]
     
    A novel electroconductive polypeptide gel based on a formation of a charge-transfer (CT) complex between poly(L-lysine) (PLL) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) was prepared. The PLL gel extensively swelled in dimethyl sulfoxide (DMSO) containing TCNQ and showed a dark green color to give PLL(+)TCNQ(-). Differential scanning calorimetric (DSC) measurement showed a significant depression of the melting temperature. The electrical conductivity of the PLL(+)TCNQ(-) gel below melting temperature of DMSO was nearly 3 orders of magnitude higher than the corresponding solution. These phenomena were explained in terms of the extensive association of DMSO molecules with the charged network through strong electrostatic interaction.
  • J. P. Gong, T. Nitta, Y. Osada
    J. Phys. Chem. 98 (38) 9583 - 9587 0022-3654 1994/09 [Refereed][Not invited]
  • J. P. Gong, M. Kawasaki, K. Fujito, R. Tsuchiya, H. Koinuma
    Physical Review B 50 (5) 3280 - 3287 0163-1829 1994/08 [Refereed][Not invited]
  • M NANTOH, T HASEGAWA, W YAMAGUCHI, A TAKAGI, M OGINO, K KITAZAWA, M KAWASAKI, JP GONG, H KOINUMA
    JOURNAL OF APPLIED PHYSICS 75 (10) 5227 - 5232 0021-8979 1994/05 [Refereed][Not invited]
     
    As-grown surfaces of c-axis-oriented laser-ablated YBa2Cu3Oy (YBCO) films have been investigated by scanning tunneling microscopy and spectroscopy (STM/STS) at 4.2 K. The square atomic arrangement with an average spacing of 0.4 nm was observed on the specimens even after exposure to ambient atmosphere, indicating that the (001) surface of the YBCO thin film was stable and free from severe contamination or chemical reaction. The STS observations revealed the semiconductive nature of the surface with a band gap of 0.1 eV However, the tunneling spectrum varied its shape depending on the tip-to-sample distance and a clear superconducting gap structure with 2DELTA approximately 40 meV appeared when the STM tip was closer to the surface than the usual position of the scanning mode, suggesting that the semiconductive layer is confined in the surface region of atomic size thickness.
  • M. Nantoh, T. Hasegawa, M. Kawasaki, J. P. Gong, K. Fujito, A. Takagi, W. Yamaguchi, M. Ogino, H. Koinuma, K. Kitazawa
    J. Superconductivity 7 (2) 349 - 353 0896-1107 1994/04 [Refereed][Not invited]
  • ソフト&ウェットマテリアル―ゲル
    グン剣萍, 長田義仁
    固体物理 30 (11) 982 - 989 1994 [Not refereed][Invited]
  • Electro-Driven Gel Actuator
    Y. Osada, H. Okuzaki, J. P. Gong
    Trends in Polym. Sci 2 61 - 66 1994 [Not refereed][Invited]
  • Electro-Driven Gel Motility on the Base of Cooperative Molecular Assembly Reaction
    Y. Osada, H. Okuzaki, J. P. Gong, T. Nitta
    Polym. Sci 36 340 - 351 1994 [Not refereed][Invited]
  • Jianping Gong, Satomi Ohnishi, Yoshihito Osada
    Polymer Journal 26 (6) 754 - 757 1349-0540 1994 [Refereed][Not invited]
  • S. Maekawa, J. P. Gong, Y. Osada
    Macromol. Rapid Commun. 15 (1) 73 - 79 1022-1336 1994/01 [Refereed][Not invited]
  • Jianping Gong, Satomi Ohnishi, Yoshihito Osada
    Polymer Journal 26 (6) 754 - 757 1349-0540 1994 [Refereed][Not invited]
  • S. Maekawa, J. P. Gong, Y. Osada
    Macromol. Rapid Commun. 15 (1) 73 - 79 1022-1336 1994/01 [Refereed][Not invited]
  • Jianping Gong, Hidenori Okuzaki, Yoshihito Osada
    Macromolecular Chemistry and Physics 195 (5) 1871 - 1876 1521-3935 1994 [Refereed][Not invited]
     
    A polymer gel formed from acrylic acid and methyl acrylate, moderately swollen in toluene or benzene, exhibits iridescent coloration. The color changes with temperature and composition of the gel. This phenomenon has been associated with specific scattering of light. © 1994 Hüthig & Wepf Verlag, Basel
  • Jian Ping Gong, Masashi Kawasaki, Kenji Fujito, Ryuta Tsuchiya, Mamoru Yoshimoto, Hideomi Koinuma
    Japanese Journal of Applied Physics 33 (1A) L20 - L23 0021-4922 1994/01 [Refereed][Not invited]
  • JP GONG, M KAWASAKI, H KOINUMA
    ADVANCED MATERIALS '93, VI - A & B 19 (A & B) 485 - 490 1994 [Refereed][Not invited]
  • K FUJITO, M KAWASAKI, JP GONG, R TSUCHIYA, M YOSHIMOTO, H KOINUMA
    ADVANCED MATERIALS '93, VI - A & B 19 (A & B) 541 - 544 1994 [Refereed][Not invited]
  • H KOINUMA, S GONDA, JP GONG, M KAWASAKI, M YOSHIMOTO, M NANTOH, T HASEGAWA, K KITAZAWA
    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS 54 (10) 1215 - 1218 0022-3697 1993/10 [Refereed][Not invited]
     
    We have fabricated high quality and chemically stable epitaxial films of YBa2Cu3O7-delta (YBCO) and SrTiO3 by pulsed laser deposition (PLD) technique and investigated their surface morphology, electronic state, and growth mode. The cryoganic STM/STS measurements on small area (4x4nm) c-oriented YBCO films resulted in the simultaneous observations of lattice images and tunneling spectra with 20meV energy gap. A gap spectrum exhibited almost zero conductance, favoring s-wave superconductivity. Wider scans of the film surfaces by AFM and SEM, however, revealed granular structure of the surfaces with a root mean square (rms) roughness of 5nm, which is far larger than the coherence length of YBCO. Much smoother surfaces were obtained for a- and (110) oriented films. Atomic images and conductive layers could be identified by STM for these films. The surface morphology of epitaxial SrTiO3 films prepared under high vacuum (<10(-5)Torr:MBE) conditions was found to be improved to such an extent as to show atomically flat images in AFM and STM analyses. By in situ XPS analyses, valence states and film growth mode of SrTiO3 epitaxial films were elucidated on an atomic layer level. Discussions are extended to the processes for controlling the growth mode and carrieres of high Tc related oxide films as well s for fabricating SIS tunnel junctions.
  • J. P. Gong, M. Kawasaki, U. Tanaka, N. Ishizawa, M. Yoshimoto, H. Koinuma, M. Kumagai, K. Hirai, K. Horiguchi
    Japanese Journal of Applied Physics 32 L687 - L689 1993/05 [Refereed][Not invited]
  • M. Kawasaki, J. P. Gong, M. Nantoh, T.Hasegawa, K. Kitazawa, M. Kumagai, K. Hirai, K. Horiguchi, M. Yoshimoto, H. Koinuma
    Japanese Journal of Applied Physics 32 1612 - 1616 1993/04 [Refereed][Not invited]
  • Y. Osada, J. P. Gong
    Progress in Polymer Science 18 (2) 187 - 226 0079-6700 1993 [Refereed][Invited]
  • H KOINUMA, M YOSHIMOTO, M KAWASAKI, H OHKUBO, N KANDA, JP GONG
    LASER ABLATION IN MATERIALS PROCESSING : FUNDAMENTALS AND APPLICATIONS 285 263 - 268 0272-9172 1993 [Refereed][Not invited]
  • JP GONG, Y OSADA
    APPLIED PHYSICS LETTERS 61 (23) 2787 - 2789 0003-6951 1992/12 [Refereed][Not invited]
     
    Metal salts of charge transfer complex such as CuTCNQ, LiTCNQ and others have been found to dissolve in water when mixed with polyethyleneimine (PEI). From electronic spectra it was supposed that metal salts of organic complex form trilateral complex with PEI in water. Homogeneous and continuous polymeric thin film was prepared by casting this solution. The film with a thickness of 150-200 nm showed field-induced bistable switching from low to high impedance regime at a field strength of 4 x 10(4) V/mm. A possible switching mechanism was briefly discussed.
  • JP GONG, KAWAKAMI, I, Y OSADA
    MACROMOLECULES 24 (25) 6582 - 6587 0024-9297 1991/12 [Refereed][Not invited]
     
    The effect of 7,7,8,8-tetracyanoquinodimethane (TCNQ) doping on the electroconductivity of cross-linked poly[N-[3-(dimethylamino)propyl]acrylamide] (PDMAPAA) gel, swollen in N,N-dimethylformamide (DMF), was investigated. The gel showed ionic conductivity as high as 10(-4) S cm-1 by TCNQ doping due to the formation of an ionic species of the charge-transfer (CT) complex between PDMAPAA gel and TCNQ. It was found that this type of CT gel undergoes rapid contraction by applying dc voltage, and the rate as well as the efficiency of the organogel much exceeded those of hydrogel. The mechanism of such an electrodriven chemomechanical contraction was explained in terms of an electrokinetic process, and the simple mathematical model of the contraction was postulated.
  • M YOSHIMOTO, H NAGATA, S GONDA, JP GONG, H OHKUBO, H KOINUMA
    PHYSICA C 190 (1-2) 43 - 45 0921-4534 1991/12 [Refereed][Not invited]
     
    Atomically regulated layers of perovskite oxides and alkaline earth cuprates were fabricated by laser MBE with the aid of RHEED intensity oscillations clearly observed during film growth. A ceramic superlattice composed of lattice-matched SrVO3-x and SrTiO3-y perovskites was prepared on an atomic scale by counting the number of RHEED oscillation. In situ RHEED and XPS analyses indicate that the interface between the laterally grown SrCuO2-z epitaxial film and the SrTiO3(001) substrate has a transition layer of about 1 nm thick, which apparently reflects an inhomogeneous growth manner at the initial stage.
  • M YOSHIMOTO, H NAGATA, JP GONG, H OHKUBO, H KOINUMA
    PHYSICA C 185 (Pt 3) 2085 - 2086 0921-4534 1991/12 [Refereed][Not invited]
     
    Pulsed laser deposition in ultrahigh vacuum was verified to be a promising method to deposit epitaxial films composed of bi-layered [(AE)2+/(CuO2)2-]n (AE = Sr or Ba) lattices. As-grown films deposited on SrTiO3(001) substrates under NO2 flushing exhibited a metallic conduction.
  • J. P. Gong, I. Kawakami, V. G. Sergeyev, Y. Osada
    Macromolecules 24 (19) 5246 - 5250 0024-9297 1991/09 [Refereed][Not invited]
  • Y OSADA, JP GONG, K SAWAHATA
    JOURNAL OF MACROMOLECULAR SCIENCE-CHEMISTRY A28 (11-12) 1189 - 1205 0022-233X 1991 [Not refereed][Invited]
     
    When a water-swollen polyelectrolyte gel is interposed between a pair of electrodes and dc is applied, the gel undergoes electrochemomechanical contraction and concomitant water exudation. Microparticles of crosslinked poly(acrylic acid) also undergoes reversible shrinkage by the electric field. The contraction was associated with the electrohydrodynamic transport of hydrated ions, and an equation expressing the rate of size change was derived as a function of voltage, charge density, and degree of swelling. Applications of this phenomenon to drug delivery systems, artificial muscles lifting and lowering a load, and some gel actuators walking in water are introduced.
  • J GONG, Y KAGAMI, K YAMADA, Y OSADA
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 63 (6) 1578 - 1583 0009-2673 1990/06 [Refereed][Not invited]
  • Y KAGAMI, K YAMADA, T YAMAUCHI, J GONG, Y OSADA
    PLASMA POLYMERIZATION AND PLASMA INTERACTIONS WITH POLYMERIC MATERIALS 46 289 - 314 1990 [Not refereed][Invited]

Books etc

  • 刺激応答性高分子ハンドブック
    高橋 陸, 龔 剣萍 (Joint work基礎編 第3章第3節 犠牲結合が拓く高強度・高靭性ゲルの新設計)
    エヌ・ティー・エス 2018/12 (ISBN: 9784860435356) 864 195-202
  • 《普及版》次世代バイオミメティクス研究の最前線–生物多様性に学ぶ–
    室﨑喬之, 龔剣萍 (Contributor第2章 機能解明 7 海藻にフジツボが付着しないのは何故か–海藻に学ぶ抗生物付着ゲルの開発–)
    シ–エムシ–出版 2017/11 350 99-109
  • 食品・化粧品・医療分野へのゲルの利用《普及版》
    Jian Ping Gong (Contributor第3章3.高強度ダブルネットワ–クゲルと関節軟骨)
    シ–エムシ–出版 2016/07 245 225-228
  • すごいぞ!身の周りの表面科学 ツルツル、ピカピカ、ザラザラの不思議
    Jian Ping Gong (Contributor第4章.摩擦の表面科学 Q35. 生体の動きが滑らかなのはなぜ?)
    講談社 2015/10 (ISBN: 9784062579407) 272 135-137
  • Encyclopedia of Polymeric Nanomaterials.
    Jamil Ahmed, Jian Ping Gong (ContributorLow–Friction Materials)
    Springe 2015/04
  • Encyclopedia of Polymeric Nanomaterials
    Tasuku Nakajima, Jian Ping Gong (ContributorDouble network hydrogels: Soft and tough IP)
    Springer 2015/04
  • ゲルテクノロジーハンドブック~機能設計・評価・シミュレーションから製造プロセス・製品化まで~
    中島 祐, グン 剣萍 (Contributorダブルネットワークゲルのからくり―犠牲結合と隠れ長)
    エヌ・ティ-・エス 2014/10
  • 生物模倣技術と新材料・新製品開発への応用
    岡崎 春香, 中島 祐, 黒川 孝幸, グン 剣萍 (Contributor第6章第1節 生体のもつ精緻な階層構造を模倣したゲルの作成とその人工軟骨、再生医療への応用)
    技術情報協会 2014/07
  • Aqueous Lubrication: Natural and Biomimetic Approaches
    Jian Liu, Jian Ping Gong (ContributorChapter 5: Hydrogel Friction and Lubrication)
    World Scientific Publishing Co. Inc 2014/05
  • 高分子ナノテクノロジーハンドブック~最新ポリマーABC技術を中心として~
    グン 剣萍, 中島祐 (Contributor第2編第4章第3節 ダブルネットワーク)
    エヌ・ティー・エス 2014/03
  • Bacterial NanoCellulose: A Sophisticated Multifunctional Material
    Md. Anamul Haque, Takayuki Kurokawa, Jian Ping Gong (ContributorChapter 4. Tough Bacterial Nanocellulose Hydrogels Based on the Double-Network Technique)
    CRC Press 2012/12
  • Technological Advancements in Biomedicine for Healthcare Applications
    Jing Jing Yang, Jian Fang Liu, Takayuki Kurokawa, Nobuto Kitamura, Kazunori Yasuda, Jian Ping Gong (Contributor)
    IGI Global 2012/10
  • ソフトナノテクノロジーにおける材料開発
    龔剣萍 (Contributor第III編 高分子ナノ材料 第4章 高強度・低摩擦ゲル)
    シーエムシー出版 2011/12
  • 次世代バイオミメティクス研究の最前線-生物多様性に学ぶ-
    室﨑喬之, 龔剣萍 (Contributor第2章 機能解明 7 海藻にフジツボが付着しないのは何故か-海藻に学ぶ抗生物付着ゲルの開発-)
    シーエムシー出版 2011/08
  • 現代表面科学シリーズ
    室﨑喬之, 楊晶晶, 龔剣萍 (Contributor第5巻 ひとの暮らしと表面科学、第5章 次世代テクノロジーのための表面科学)
    共立出版 2011/07
  • 未来を動かすソフトアクチュエータ―高分子・生体材料を中心とした研究開発―
    角五彰, 龔剣萍 (Contributor第31章ATP駆動型ソフトバイオマシンの創製)
    シーエムシー出版 2010/12
  • High Solid Dispersion
    Jian Ping Gong, Yoshihito Osada (Contributor)
    Springer-Verlag Berlin Heidelberg 2010/11
  • Biomedical Applications of Hydrogels Handbook
    Takayuki Murosaki, Jian Ping Gong (Contributor)
    Springer Science+Business Media 2010/10
  • Advances in Polymer Science, Special Volume: High Solid Dispersion
    Jian Ping Gong, Yoshihito Osada (Contributor)
    Springer Verlag (Heidelberg) 2010/07
  • Biomedical Applications of Hydrogels Handbook
    Springer 2010
  • 現代界面コロイド科学の事典
    丸善 2010
  • 食品・化粧品・医療分野へのゲルの利用
    シーエムシー出版 2010
  • 驚異のソフトマテリアル―最新の機能性ゲル研究
    化学同人 2010
  • Chemomechanical Instabilities in Responsive Materials
    GONG Jian Ping (Contributor)
    Springer 2009/12
  • ソフトマター 分子設計・キャラクタリゼーションから機能性材料まで
    丸善 2009
  • 高分子ゲルの動向―つくる・つかう・みる―
    シーエムシー出版 2009
  • Chemomechanical Instabilities in Responsive Materials
    Springer 2009
  • ゲルコントロール―ゲルの上手な作り方とゲル化の抑制
    情報機構 2009
  • 超分子サイエンス&テクノロジー~基礎からイノベーションまで~
    エヌ・ティー・エス 2009
  • 高分子表面・界面分析法の新展開
    シーエムシー出版 2009
  • Surfactants in Tribology
    GONG Jian Ping (Contributor)
    CRC Press 2008/06
  • Surfactants in Tribology
    CRC Press 2008
  • 医療用ゲルの最新技術と開発
    シーエムシー出版 2008
  • Bottom-up Nanofabrication: Supramolecules, Self-Assemblies, and Organized Films
    GONG Jian Ping (Contributor)
    American Scientific Publishers, California, USA 2007/10
  • Intelligent Materials
    GONG Jian Ping (Contributor)
    RSC Publishing, UK 2007/09
  • Macromolecular Engineering: Precise Synthesis Materials Properties, Applications
    GONG Jian Ping (Contributor)
    Wiley-VCH 2007/04
  • Bottom-up Nanofabrication: Supramolecules, Self-Assemblies, and Organized Films
    American Scientific Publishers 2007
  • Intelligent Materials
    RSC Publishing 2007
  • Macromolecular Engineering: Precise Synthesis Materials Properties, Applications
    Wiley-VCH 2007
  • バイオとナノの融合Ⅱ-新生命科学の応用
    北海道大学出版会 2007
  • バイオとナノの融合Ⅰ-新生命科学の基礎
    北海道大学出版会 2007
  • “ファイバー”スーパーバイオミメティックス
    エヌ・ティー・エス 2006
  • 基礎高分子科学
    東京化学同人 2006
  • 図解 高分子新素材のすべて―21世紀の機能材料をひも解く
    工業調査会 2005
  • ソフトナノテクノロジー ―バイオマテリアル革命
    シーエムシー出版 2005
  • ナノマテリアルハンドブック
    エヌ・ティー・エス 2005
  • Reflexive Polymers and Hydrogels: Understanding and designing fast-responsive polymeric systems
    GONG Jian Ping (Contributor)
    CRC Press Inc. (London) 2004/03
  • ソフトアクチュエーター開発の最前線~人工筋肉の実現を目指して~
    エヌ・ティー・エス 2004
  • Reflexive polymers and hydrogels: Understanding and designing fast-responsive polymeric systems
    CRC Press 2004
  • 高分子ゲルの最新動向
    シーエムシー出版 2004
  • インテリジェント材料・技術の最新開発動向
    シーエムシー出版 2003
  • Polymer Gels and Networks
    GONG Jian Ping (Contributor)
    Marcel Dekker, Inc., 2001/12
  • Polymer Gels and Networks
    Marcel Dekker, Inc. 2001
  • Electrical and Optical Polymer Systems: Fundamentals, Methods, and Applications
    GONG Jian Ping (Contributor)
    Marcel Dekker, Inc. 1998/01
  • Electrical and Optical Polymer Systems: Fundamentals, Methods, and Applications
    Marcel Dekker, Inc. 1998
  • Functional Monomers and Polymers, Second Edition
    Jian Ping Gong (Contributor)
    Marcel Dekker, Inc. 1997/07
  • 『ゲルハンドブック』
    エヌ・ティー・エス 1997
  • Polymeric Materials Encyclopedia
    Jian Ping Gong (Contributor)
    CRC Press 1996

Conference Activities & Talks

  • Multi-scale design of polyampholyte hydrogels for toughness, self-healing, adhesion and composites  [Invited]
    Jian Ping Gong
    The 13th International Symposium on Polyelectrolytes (ISP2020)
  • ソフトフォトニッククリスタルの創製  [Invited]
    龔 剣萍
    高分子学会精密ネットワークポリマー研究会講演会  2021/06
  • Rapid Thermal Switching from Hydrogel to Plastic  [Invited]
    Jian Ping Gong
    The 48th World Polymer Congress (IUPAC-MACRO2020+)  2021/05
  • Double Network Hydrogels for Biological Applications  [Invited]
    Jian Ping Gong
    Biohydrogels 2021  2021/04
  • Self-growing of double network hydrogels by mechanical training  [Invited]
    Jian Ping Gong
    ACS Spring 2021 National Meeting: Macromolecular Chemistry at the Dawn of Its Second Century  2021/04
  • Fatigue fracture of self-healing polyampholyte hydrogels with hierarchical structure  [Invited]
    Jian Ping Gong
    Spring ACS 2021 National Meeting: Fundamentals of Polymer Mechanics Symposium
  • Hydrogels: Challenges and Opportunities  [Invited]
    Jian Ping Gong
    ACS Macro Letters 10th Anniversary Webinar Series: Polymer Physics/Physical Chemistry  2021/03
  • Jian Ping Gong
    Extreme Mechanics Letter (EML) Webinar  2020/12
  • 高靭性複合材料の設計と創製  [Invited]
    龔剣萍
    第29回ポリマー材料フォーラム  2020/11
  • Dynamic hydrogels inspired from nature  [Invited]
    グン剣萍
    第95回高分子若手研究会[関西]  2020/11
  • 金属を凌駕する高靭性複合材料のデザインと創製  [Invited]
    Jian Ping Gong
    TEIJIN MIRAIフォーラム  2020/02
  • 鍛えて成長するゲル ―破壊による創造の材料科学―  [Invited]
    Jian Ping Gong
    東京工業大学「第18回生体医歯工学公開セミナー」  2019/12
  • Fiber Reinforced Hydrogels With Extra-Ordinarily High Toughness  [Invited]
    Jian Ping Gong
    Materials Research Meeting 2019 (MRM2019)  2019/12
  • Self-growing hydrogels by repetitive mechanical training  [Invited]
    Jian Ping Gong
    CEMS International Symposium on Supramolecular Chemistry and Functional Materials 2019 (CEMSupra2019)  2019/12
  • Strengthening materials using weak bonds-A novel strategy  [Invited]
    Jian Ping Gong
    Millennium Science Forum  2019/11
  • Self-Growing Materials under Mechanical Training  [Invited]
    Jian Ping Gong
    JST CREST International Workshop New Developments toward Wearable Photonics: From Materials to Devices  2019/10
  • Growing Hydrogels by Structure Destruction and Reconstruction Under Mechanical Training  [Invited]
    Jian Ping Gong
    The 7th Asian Symposium on Advanced Materials (ASAM-7  2019/09
  • Molecular design of self-growing hydrogels in response to mechanical training  [Invited]
    Jian Ping Gong
    DoDyNet Summer School  2019/07
  • Self-growing hydrogels by repetitive mechanical training  [Invited]
    Jian Ping Gong
    The 3nd International Symposium for Advanced Gel Materials & Soft Matters  2019/06
  • Self-growing double network hydrogels by repetitive mechanical training  [Invited]
    Jian Ping Gong
    Frontiers in Polymer Science2019  2019/05
  • Molecular design of tough hydrogels with sacrificial bonds mechanism  [Invited]
    Jian Ping Gong
    Xing-Da Lecture  2019/03  Beijing  College of Chemistry and Molecular Engineering, Peking University
  • Multi-scale Design of Hydrogels with Reversible Sacrificial Bonds – From Toughness to Adhesion to Composites  [Invited]
    Jian Ping Gong
    Soft Matter Physics: from the perspective of the essential heterogeneity  2018/12
  • Hydrogels with Dynamic Sacrificial Bonds – From Toughness to Adhesion to Composites –  [Invited]
    Jian Ping Gong
    The 9th International Conference on Multiscale Materials Modeling(MMM2018)  2018/10
  • ハードマターからソフトマターへ、世界をかける  [Invited]
    グン 剣萍
    第8回CSJ化学フェスタ  2018/10
  • Novel Hydrogels with Reversible Sacrificial Bonds- From Toughness to Wet Adhesion to Composites -  [Invited]
    GONJian Ping Gong
    Japan-Korea Joint Symposium on Polymer Science 2018 (JKJS2018)  2018/07
  • In vivo robust bonding of double network hydrogels to bones  [Invited]
    Jian Ping Gong
    World Polymer Congress (MACRO2018)  2018/07
  • Autonomous Mechanical Remodelling of Double Network Hydrogels  [Invited]
    Jian Ping Gong
    82nd Prague Meeting on Macromolecules - Polymer Networks and Gels 2018 and 24th Polymer Network Group Meeting (PNG2018)  2018/06
  • Deformation of 1D photonic hydrogels with lipid bilayers  [Invited]
    Jian Ping Gong
    The 4th International Workshop on Soft Machines and Mechanics  2018/06
  • Tough physical double network hydrogels based on tri-block copolymers  [Invited]
    Jian Ping Gong
    The 13th International Symposium on Polymer Physics (PP'2018)  2018/06
  • Jian Ping Gong
    17th International Conference on Deformation, Yield and Fracture of Polymers  2018/03
  • Jian Ping Gong
    French National Conference on Polymers  2017/11  Ecole Nationale Supérieure d'Architecture de Montpellier (ENSAM), Paris, France
  • Hydrogels Based on Polymer Association: Toughness, Self-healing, and Adhesion  [Invited]
    Jian Ping Gong
    Final SUPOLEN Conference  2017/09
  • Hydrogels with Reversible Sacrificial Bonds: Tough, Self-healing, Adhesion  [Invited]
    Jian Ping Gong
    Seminar at Changchun Applied Chemistry Institute  2017/08
  • Hydrogels with Reversible Sacrificial Bonds: tough, self-healing, adhesion  [Invited]
    Jian Ping Gong
    International Symposium on Advanced Polymeric Materials 2017 (ISAPM 2017)  2017/08
  • Tough soft composites based on sacrificial bond mechanism  [Invited]
    Jian Ping Gong
    The 2nd International Symposium for Advanced Gel Materials & Soft Matters (ISAGMSM)  2017/08
  • 金属を凌駕する繊維強化ゲルコンポジットのデザインと創製  [Invited]
    Jian Ping Gong
    17-1高分子学会講演会  2017/07
  • Could we observe the single chain behavior at ultimate extension via double network gel?  [Invited]
    Jian Ping Gong
    2017 Telluride Science Research Conference (TSRC) on Polymer Physics  2017/06
  • Toughening soft materials with sacrificial bonds  [Invited]
    Jian Ping Gong
    50th Anniversary of Macromolecules Sympo at the 253rd ACS National Meeting  2017/04
  • フォトニックソフトマターの創成と機能制御  [Invited]
    Jian Ping Gong
    日本化学会第97春季年会(2017)  2017/03
  • Self-healing and Self-Adjustable Adhesion of Polyampholyte Hydrogels  [Invited]
    Jian Ping Gong
    GelSympo2017  2017/03
  • 高強度ダブルネットワークゲルとその軟骨治療への応用  [Invited]
    Jian Ping Gong
    第67回医用高分子研究会  2017/03
  • ダブルネットワークゲルとその高靱性原理  [Invited]
    Jian Ping Gong
    関西大学先端科学技術シンポジウム  2017/01
  • 高靱性ゲルの創製とその応用展開  [Invited]
    龔 剣萍
    高分子学会北陸支部研究発表会  2016/11
  • Toughening of soft materials with sacrificial bonds  [Invited]
    Jian Ping Gong
    The International Rubber Conference (IRC) "Gels and Related Soft Materials" Session  2016/10
  • Tough soft materials with sacrificial bonds  [Invited]
    Jian Ping Gong
    The 1st International Symposium On Advanced Gel Materials & Soft Matters  2016/10
  • 犠牲結合原理による高靱性ソフトマテリアルの創製  [Invited]
    龔 剣萍
    第9回 ChemBioハイブリッドレクチャー  2016/10
  • 水和ゲルの表面摩擦と潤滑-生体低摩擦の謎に迫る  [Invited]
    龔 剣萍
    第67回コロイドおよび界面化学討論会  2016/09
  • 高靱性ゲルの新展開  [Invited]
    龔 剣萍
    第65回高分子討論会  2016/09
  • 可逆的犠牲結合による高靭性・自己修復性ゲル  [Invited]
    龔 剣萍
    日本セラミックス協会第29回秋季シンポジウム  2016/09
  • Polyampholyte hydrogels: tough, self-healing, and self-adjustable adhesion  [Invited]
    龔 剣萍
    第54回高分子材料自由討論会  2016/07
  • Polyampholyte hydrogels: tough, self-healing, and self-adjustable adhesion  [Invited]
    Jian Ping Gong
    11th International Symposium “Polyelectrolytes 2016”  2016/06
  • 高分子ゲル  [Invited]
    龔 剣萍
    高分子基礎講座  2016/06
  • Build Tough Hydrogels with Sacrificial Bonds  [Invited]
    Jian Ping Gong
    Seminar at Okinawa Institute of Science and Technology  2016/04
  • Toughening of Hydrogels Based on Sacrificial Bonds Principle  [Invited]
    Jian Ping Gong
    20th MS-Seminar  2016/02
  • Tough Double Network Hydrogels and Its Cartilage Application  [Invited]
    Jian Ping Gong
    The International Symposium on “Artificial Hydrogel Cartilage, Joint Replacements and Related Topics”  2016/01
  • Self-healing Hydrogels From Bilayer Membrane  [Invited]
    Jian Ping Gong
    Pacifichem 2015: Polymer Gels as Advanced Soft Materials  2015/12
  • Friction of Hydrogels by Dynamic Polymer Adsorption  [Invited]
    Jian Ping Gong
    The 14th Pacific Polymer Conference: Stimuli-Responsive and Self-Healing Polymers  2015/12
  • Structure and Dynamics of Self-healing Polyampholyte Hydrogels  [Invited]
    Jian Ping Gong
    The 14th Pacific Polymer Conference: Polymer Physics and Processing: Networks and Gels  2015/12
  • 可逆的犠牲結合による高靭性・自己修復性ゲル  [Invited]
    龔 剣萍
    日本ゾル-ゲル学会討論会  2015/11
  • Build Tough and Self-healing Hydrogels from Reversible Sacrificial Bonds  [Invited]
    Jian Ping Gong
    Japan-Belgium Symposium on Polymer Science  2015/11
  • Tough Hydrogels from Sacrificial Bonds  [Invited]
    Jian Ping Gong
    IUPAC 11th International Conference on Advanced Polymers via Macromolecular Engineering (APME2015)  2015/10
  • Build Tough Hydrogels with Sacrificial Bonds  [Invited]
    Jian Ping Gong
    中国化学会2015年全国高分子学術論文報告会  2015/10
  • 高強度・高靭性ゲルの基礎と応用  [Invited]
    Jian Ping Gong
    高分子学会2015年度Webinar  2015/10
  • Build Tough and Self-healing Hydrogels from Reversible Sacrificial Bonds  [Invited]
    Jian Ping Gong
    Japan-Taiwan Bilateral Polymer Symposium (JTBS2015)  2015/09
  • Hydrogels: An emerging material for a sustainable world  [Invited]
    Jian Ping Gong
    The Seventh International Symposium on Engineering Plastics (EP’2015)  2015/08
  • Tough and self-healing hydrogels based on reversible sacrificial bonds  [Invited]
    Jian Ping Gong
    5th International Conference on Self-Healing Materials (ICSHM2015)  2015/06
  • 高分子ゲル  [Invited]
    グン 剣萍
    高分子基礎講座  2015/06
  • Building tough soft materials with sacrificial bonds  [Invited]
    Jian Ping Gong
    Structured Soft and Biological Matter Symposium  2015/06
  • Tough Hydrogels with Sacrificial Bonds  [Invited]
    Jian Ping Gong
    10th Annual European Rheology Conference (AERC 2015)  2015/04
  • Tough Hydrogels: Bridging the Gap between Soft Materials and Supportive Tissues  [Invited]
    Jian Ping Gong
    2015 Eastman Lecture  2015/03
  • Control Hydrogel Friction and Lubrication by Surface Geometry  [Invited]
    Shintaro Yashima, Takayuki Kurokawa, Jian Ping Gong
    The joint symposium of the 22nd Polymer Networks Group Meeting (PNG) and the 10th international gel symposium (GelSympo)  2014/11
  • Self-healing tough hydrogels based on reversible sacrificial bonds  [Invited]
    Jian Ping Gong
    3rd DSM Symposium on Materials Sciences  2014/10
  • Fracture of double network hydrogels  [Invited]
    Jian Ping Gong
    SoftComp topical workshop “FRACTURE OF SOFT MATERIALS: from soft solids to complex fluids”  2014/10
  • “犠牲結合原理” によるタフポリマーの創製  [Invited]
    グン 剣萍
    革新的研究開発推進プログラム(ImPACT)超薄膜化・強靭化「しなやかなタフポリマー」の実現ワークショップ  2014/09
  • Build Sacrificial Bonds to Toughen Soft Materials  [Invited]
    Jian Ping Gong
    DSM Science Summit  2014/09
  • 犠牲結合原理による高強度・高靱性ゲルの創製  [Invited]
    グン 剣萍
    平成26年度全国大学化学系教育研究集会  2014/09
  • 犠牲結合を用いた高強度・高靱性ゲルの開発  [Invited]
    グン 剣萍
    平成26年度未踏科学サマー道場  2014/08
  • Friction of Hydrogel-Towards its relevance to bio-lubrication  [Invited]
    Jian Ping Gong
    2014 Gordon Research Conference on Tribology  2014/07
  • Build Sacrificial Bonds to Toughen Soft Materials  [Invited]
    Jian Ping Gong
    IUPAC World Polymer Congress 2014  2014/07
  • 高分子ゲル  [Invited]
    グン 剣萍
    高分子基礎講座  2014/06
  • Control of Hydrogel Sliding Friction by Surface Geometrical Patterns  [Invited]
    Shintaro Yashima, Takayuki Kurokawa, Jian Ping Gong
    11th International Symposium of Polymer Physics (PP2014)  2014/06
  • 高靭性・高機能ゲルの創製と応用展開  [Invited]
    グン剣萍
    北海道大学・北海道総合研究機構連携セミナー  2014/06
  • Tough hydrogels: Play with sacrificial bonds  [Invited]
    Jian Ping Gong
    IUTAM Symposium on Mechanics of Soft Active Materials  2014/05
  • Tough Hydrogels Based on Double Network Concept  [Not invited]
    Jian Ping Gong
    Pressure Sensitive Tape Council Tape Summit 2014 TECH 37  2014/05
  • 高靱性ゲルと犠牲結合  [Invited]
    グン 剣萍
    第17回バイオテンプレート研究懇談会  2014/03
  • Hydrogels -The key material for life science  [Invited]
    Jian Ping Gong
    2nd CRED Symposium for Academic Drug Discovery  2014/02
  • 可逆的犠牲結合による高靭性・自己修復性ゲルの創製  [Invited]
    グン 剣萍
    ERATO高原ソフト界面プロジェクト最終報告会  2014/01
  • 可逆的犠牲結合による新規高靭性・自己修復性ゲルのデザインと創製  [Invited]
    グン 剣萍
    平成25年度東海シンポジウム  2014/01
  • Tough hydrogels based on sacrificial bond principle  [Invited]
    Jian Ping Gong
    2nd Michelin-ESPCI ParisTech workshop - 2013  2013/12
  • Polyampholyte Hydrogels: A Novel Tough and Self-healing Material  [Invited]
    Tao Lin Sun, Abu Bin Ihsan, Takayuki Kurokawa, Tasuku Nakajima, Jian Ping Gong
    The 13th Pacific Polymer Conference (PPC13)  2013/11
  • 可逆的犠牲結合による高靭性・自己修復性ゲルの創製と応用展開  [Invited]
    グン 剣萍
    第22回高分子ゲル研究会講座  2013/11
  • Tough hydrogels based on double network concept  [Invited]
    Jian Ping Gong
    The 3rd International Soft Matter Conference (ISMC13)  2013/09
  • Sacrificial bond principle for toughening of hydrogels  [Invited]
    Jian Ping Gong
    9th World Congress of Chemical Engineering (WCCE9) & 15th Asian Pacific Confederation of Chemical Engineering Congress (APCChE2013)  2013/08
  • ゲルの摩擦と潤滑-その複雑性と多様性  [Invited]
    グン 剣萍
    ポリマーフロンティア21  2013/06  東工大蔵前会館 ロイアルブルーホール(東京都目黒区)
  • Tough hydrogels based on sacrificial bond principle  [Invited]
    Jian Ping Gong
    TIT International Research Center of Macromolecular Science, Special Symposium 2013 & Third Symposium on Gel and Rubber  2013/05
  • Tough hydrogels based on double network concept  [Invited]
    グン 剣萍
    数学連携研究センター第29回数学連携サロン  2013/04
  • Tough double network hydrogels as antifouling materials  [Invited]
    Jian Ping Gong
    "Marine Biosurfaces and Interfaces” Symposium at the 245th ACS National Meeting  2013/04
  • 可逆的犠牲結合による多機能ゲルの設計と創製-高靱性・自己修復・形状記憶  [Invited]
    Md. A. Haque, 孫桃林, A. B. Ihsan, 中島祐, 黒川孝幸, 龔 剣萍
    日本化学会第93春季年会(2013)アドバンスト・テクノロジー・プログラム(ATP)セッション  2013/03
  • Friction and lubrication of hydrogel-Towards its relevance to bio-lubrication-  [Invited]
    Jian Ping Gong
    北海道大学触媒化学研究センター(CRC)国際シンポジウム  2013/02
  • ゼリーとバイオミメティクス  [Invited]
    グン 剣萍
    バイオミメティクス市民セミナー  2013/01
  • Tough, Self-healing, and Shape Memory of Hydrogels Based on Reversible Sacrificial Bonds  [Invited]
    Jian Ping Gong
    2012 Japan-USA Seminar on Polymer Synthesis: Advances at the Interface of Sustainability and Polymer Synthesis  2012/12
  • Anisotropic hydrogel based on lamellar bilayers: machano-chromatics and toughness  [Invited]
    Md. Anamul Haque, Takayuki Kurokawa, Jian Ping Gong
    6th International Workshop on Advance Materials Science and Nanotechnology (IWAMSN-2012)  2012/11
  • Tough hydrogels with reversible sacrificial bonds  [Invited]
    Jian Ping Gong
    9th International Symposium on Polymer Gels (Gelsympo2012)  2012/10
  • 高強度・高靭性ゲルのデザインと創成  [Invited]
    グン 剣萍
    日本ゴム協会関西支部サタデーセミナー第34回  2012/10
  • 可逆的犠牲結合による高靭性・自己修復性ゲルの創製  [Invited]
    グン 剣萍
    第61回高分子討論会  2012/09
  • 犠牲結合によるハイドロゲルの高靱性化  [Invited]
    グン 剣萍
    破壊、亀裂、転位の勉強会  2012/08
  • Tough Hydrogels with Reversible Sacrificial Bonds  [Invited]
    Jian Ping Gong
    The 2012 Gordon Research Conference on Polymer Physics  2012/07
  • 高分子ゲル  [Invited]
    グン 剣萍
    高分子基礎講座(2012年)  2012/06
  • Lamellar bilayers as reversible sacrificial bonds for toughening of hydrogel  [Invited]
    Md. Anamul Haque, Takayuki Kurokawa, Jian Ping Gong
    International Symposium on Polymer Physics (PP'2012), Chendu  2012/06
  • Lamellar bilayers as reversible sacrificial bonds for toughening of hydrogel  [Invited]
    Md. Anamul Haque, Takayuki Kurokawa, Jian Ping Gong
    Workshop on Water Science(理化学研究所理事長ファンド指定型 「水科学」ワークショップ 『水の多様性を極める』-水科学の現在と未来-)  2012/05
  • 犠牲結合原理に基づく新規高靭性ゲルのデザインと創製  [Invited]
    グン 剣萍
    12-1精密ネットワークポリマー研究会  2012/04
  • Lamellar Bilayers as Reversible Sacrificial Bonds for Toughening of Hydrogel  [Invited]
    Md. Anamul Haque, Takayuki Kurokawa, Jian Ping Gong
    2012 Conference on Deformation, Yield and Fracture in Polymers  2012/04
  • 高靭性ゲルのデザインと創製  [Invited]
    グン 剣萍
    北海道大学・高エネルギー加速器研究機構連携シンポジウム  2012/03
  • 海洋生物に学ぶ防汚材料の設計と創製  [Invited]
    室﨑喬之, 黒川孝幸, 龔 剣萍
    日本化学会第92春季年会(2012)アドバンスト・テクノロジー・プログラム(ATP)セッション  2012/03
  • 高弾性・高靭性ダブルネットワークゲルの創成とその分子機構の解明  [Invited]
    グン 剣萍
    日本化学会第92春季年会(2012)  2012/03
  • Creation of tough hydrogels for artificial bio-tissues  [Invited]
    Jian Ping Gong
    Bangladesh Chemical Congress 2011 (34th Annual Conference of Bangladesh Chemical Society)  2011/12
  • Molecular design of tough hydrogels-Play with the delicate balance between sacrificial bond and hidden length  [Invited]
    Jian Ping Gong
    International Seminar on Supramolecular Chemistry  2011/12
  • Hydrogel: A Soft and Wet Material for the Age of Life Science  [Invited]
    Jian Ping Gong
    Mukarram Hussain Khundker Memorial Lecture  2011/12
  • ゲルが見せてくれるウェットマテリアルの世界  [Invited]
    グン 剣萍
    第1回ウェットデバイス研究会  2011/11
  • バイオマテリアルとしての多機能ハイドロゲル  [Invited]
    黒川孝幸, 龔 剣萍
    日本動物実験代替法学会第24回大会 代替法とマイクロ・ナノテクノロジー  2011/11
  • Anisotropic, Tough Hydrogel Containing Single Domain Lamellar Bilayer  [Invited]
    Jian Ping Gong
    2011 Taiwan-Japan Bilateral Polymer Symposium  2011/09
  • Lamellar Bilayers as Reversible Sacrificial Bonds to Toughen Hydrogel  [Invited]
    Jian Ping Gong
    第一回ソフトマター研究会  2011/08
  • Fracture of tough double network hydrogel  [Invited]
    Jian Ping Gong
    Gordon Research Conference on Adhesion Science 2011  2011/07
  • 可逆的犠牲結合の導入による自己修復能を持つ高靭性ゲルの創製  [Invited]
    グン 剣萍
    高分子分析研究懇談会夏期合宿  2011/07
  • 高機能ゲルの創製と生体構造材料への応用展開  [Invited]
    グン 剣萍
    第14回化学工学北海道アカシアセミナー  2011/07
  • 高分子ゲル  [Invited]
    グン 剣萍
    高分子基礎講座(2011年)  2011/06
  • 高強度ダブルネットワークゲルにおける犠牲結合と隠れ長のからくり  [Invited]
    グン 剣萍
    ナノ学会第9回大会  2011/06
  • DN Gels as meniscus substitutes  [Invited]
    Jian Ping Gong
    5th Basel International Knee Congress and Instructional Course  2011/05
  • 生命科学時代の新材料―高弾性・高靭性ゲルの創成  [Invited]
    グン 剣萍
    2011年度帝人21世紀フォーラム  2011/01
  • ダブルネットワークゲルの創成と応用  [Invited]
    グン 剣萍
    化学技術戦略推進機構 機能性材料分科会・講演会  2011/01
  • A molecular stent method to synthesize tough double network hydrogels from neutral polymers  [Invited]
    Jian Ping Gong
    Macromolecular Materials Gordon Research Conference  2011/01
  • Why is a double-network gel so tough: a discussion on its common features with tough tissues  [Invited]
    Jian Ping Gong
    Pacifichem 2010  2010/12
  • なぜDNゲルが強いか-ゴムとの接点を探る  [Invited]
    グン 剣萍
    日本ゴム協会関東支部技術講演会  2010/12
  • Hydrogegl: A Soft and Wet Materials as Load-bearing Bio-tissues  [Invited]
    Jian Ping Gong
    8th France-Japan Workshop on Nanosciences and Nanomaterials  2010/11
  • ダブルネットワークゲルが切り開く新天地  [Invited]
    グン 剣萍
    第59回高分子討論会「フォーカスセッション」  2010/09
  • Why are double network hydrogels so tough?  [Invited]
    Jian Ping Gong
    International Symposium on Non-Equilibrium Soft Matter 2010  2010/08
  • Toughening Mechanism of Double Network Hydrogels  [Invited]
    Jian Ping Gong
    Pacific Rim Conference on Rheology (PRCR-5), Elastomers and Gels  2010/08
  • Play with the Tough Double Network Hydrogels  [Invited]
    Jian Ping Gong
    Macro2010: 43rd IUPAC World Polymer Congress  2010/07
  • Learn from nature: cartilage-like tough double network gels  [Invited]
    Jian Ping Gong
    2010 Japan-Taiwan Bilateral Polymer Symposium  2010/07
  • 高分子ゲル  [Invited]
    グン 剣萍
    高分子基礎講座(2010年)  2010/06
  • Anisotropic Hydrogels with High Mechanical Strength and Self-recovery by Incorporating Lipid-like Lamellar Structure  [Invited]
    Jian Ping Gong
    PP’2010, Ji’nan  2010/06
  • Hydrogel: A Soft and Wet Material as Load-Bearing Bio-tissues  [Invited]
    Jian Ping Gong
    MANA Seminar  2010/05
  • Soft and Wet Hydrogel: A Key Material for the Age of Life Science  [Invited]
    Jian Ping Gong
    International Conference on Electronics Pacakging 2010  2010/05
  • なぜDNゲルが強いか-ゴムとの接点を探る  [Invited]
    グン 剣萍
    東京工業大学国際高分子基礎研究センター特別シンポジウム  2010/04
  • Tough hydrogels with a double network structure  [Invited]
    Jian Ping Gong
    Focus Session on Polymer Network Mechanics at the 2010 March Meeting of the American Physical Society  2010/03
  • Learn from nature: cartilage-like tough double network gels  [Invited]
    Jian Ping Gong
    The Second Symposium on Academic Exchange and Collaborative Research between GSE-HU and MRC-ETHZ  2010/02
  • Learn from nature: cartilage-like tough double network gels  [Invited]
    Jian Ping Gong
    Tenth International Symposium on Biomimetic Materials Processing (BMMP-10)  2010/01
  • 生命科学時代の新材料:高強度・高靭性ダブルネットワークゲルの創製  [Invited]
    Green Sustainable Chemistry (GSC) Symposium, 第, 回GSCシンポジウム
    ゴム協会配合技術研究分科会  2009/11
  • 生命科学時代の新材料:高強度・高靭性ダブルネットワークゲルの創製  [Invited]
    龔 剣萍
    オルガテクノ2009  2009/11
  • Hydrogel: A novel material for the age of life science  [Invited]
    Jian Ping Gong
    2nd Asian Symposium on Advanced Materials (ASAM-2)  2009/10
  • Cartilage-like tough double network gels  [Invited]
    Jian Ping Gong, Takayuki Kurokawa, Kazunori Yasuda
    Third Switzerland-Japan Workshop on Biomechanics 2009 (SJB 2009)  2009/09
  • ゼリーを軟骨に作り変えよう  [Invited]
    Green Sustainable Chemistry (GSC) Symposium, 第, 回GSCシンポジウム
    第7回化学イノベーションシンポジウム  2009/08
  • 高強度DNゲルから生体創発の謎に迫る  [Invited]
    Green Sustainable Chemistry (GSC) Symposium, 第, 回GSCシンポジウム
    09年度高分子学会第1回講演会  2009/07
  • 高分子ゲル  [Invited]
    グン 剣萍
    高分子基礎講座(2009年)  2009/06
  • 生命科学時代の新材料―ソフト&ウェットマテリアルの創製  [Invited]
    Green Sustainable Chemistry (GSC) Symposium, 第, 回GSCシンポジウム
    第26回ライラックセミナー・第15回若手研究者交流会  2009/06
  • Tough DN gel  [Invited]
    Jian Ping Gong
    14th International Conference on Deformation, Yield and Fracture of Polymers  2009/04
  • ゲルの摩擦と潤滑-生体界面低摩擦の謎に迫る  [Invited]
    Green Sustainable Chemistry (GSC) Symposium, 第, 回GSCシンポジウム
    新学術領域研究(領域提案型)「ソフトインターフェースの分子科学」第一回公開シンポジウム  2009/01
  • 高強度DNゲルの創製‐生体創発の謎に迫る  [Not invited]
    セルロース学会第16回年次大会  2009
  • Soft and Wet Hydrogel: A Human-friendly Material  [Invited]
    Jian Ping Gong
    IUMRS-ICA2008 (Frontier of Polymeric Nano-Soft-Materials - Precision Polymer Synthesis, Self-assembling and Their Functionalization)  2008/12
  • Friction between Like-Charged Hydrogels—Combined Mechanisms of Boundary, Hydrated, and Elastohydrodynamic Lubrication  [Invited]
    Jian Ping Gong
    5th International Symposium on Surface Science and Nanotechnology  2008/11
  • 軟骨のような強くて滑らかなゲル  [Invited]
    龔 剣萍
    未来高分子教室:高分子で展開するバイオ・光・ナノテクが織りなす実体験ゾーン  2008/10
  • Bio-Inspired Soft & Wet Materials: From Hydrogels to Bio-Tissues  [Invited]
    Jian Ping Gong
    UK-Japan Frontiers of Science Symposium 2008  2008/10
  • Soft and Wet Hydrogel: A Key Material for the Age of Life Science  [Invited]
    Jian Ping Gong
    Bio & Polymers –New Polymer Technologies with Water-, Biannual Meeting of the GDCh-Division of "Macromolecular Chemistry"  2008/09
  • From Hydrogel to Soft Tissue: Learn from Nature  [Invited]
    Jian Ping Gong
    International Symposium on Polymer Physics (ISPP)  2008/09
  • ゲル-生命科学時代の新材料  [Invited]
    龔 剣萍
    薄膜技術研究会特別講演会  2008/08
  • Friction of soft gel in polymer solution  [Invited]
    Jian Ping Gong, Miao Du, Yasuyuki Maki
    17th International Symposium on Surfactants in Solution  2008/08
  • Friction & Lubrication of Gels - Towards its Relevance to Biolubrication  [Invited]
    Jian Ping Gong
    Gordon Conference on Tribology  2008/07
  • 高分子ゲル  [Invited]
    グン 剣萍
    高分子基礎講座(2008年)  2008/06
  • Friction-Lubrication Transition of Hydrogel  [Invited]
    Jian Ping Gong
    International Symposium on Polymer Physics (PP’2008)  2008/06
  • ゲルの摩擦・潤滑から生体の低摩擦へ  [Invited]
    龔 剣萍
    第31回日本バイオレオロジー学会年会  2008/06
  • 生命科学時代が求める新材料―ソフト&ウエットマテリアルの創製  [Invited]
    龔 剣萍
    第3回「デジタル医工学を学ぶためのベンチャ-人材育成教育」講演会  2008/03
  • 生命科学時代が求める新材料―ソフト&ウェットマテリアルの創成  [Invited]
    龔 剣萍
    Green Sustainable Chemistry (GSC) Symposium(第8回GSCシンポジウム  2008/03
  • 生命科学の時代が求める新材料―ソフト&ウェットマテリアルの創成  [Invited]
    龔 剣萍
    帝人21世紀フォーラム  2008/02
  • 生命科学時代が求める新材料―ソフト&ウェットマテリアルの創成  [Not invited]
    第2回北海道大学医学研究科連携研究センターシンポジウム「医療を取りまく多領域融合研究の展開」  2008
  • Cartilage-like tough gel with low friction  [Not invited]
    Jian Ping Gong
    Second International Conference on Mechanics of Biomaterials & Tissues  2007/12
  • ソフト&ウェットマターの潤滑と接着  [Invited]
    龔 剣萍
    学術創成研究費「パルス中性子源を活用した量子機能発現機構に関する融合研究」第7回研究会  2007/11
  • 生体軟組織様ゲルの創製とその機能解明  [Invited]
    龔 剣萍
    物性研究所短期研究会「物性化学のフロンティア2007」  2007/11
  • 高分子ゲルの摩擦と水和潤滑-その多様性と複雑性  [Invited]
    龔 剣萍
    高分子表面研究会  2007/10
  • Hydrogel - A Soft and Wet Material as Artificial Living Tissue  [Invited]
    Jian Ping Gong
    中国2007全国高分子学会論文報告会  2007/10
  • Tough Hydrogel - Learn from Nature  [Invited]
    Jian Ping Gong
    Asian Symposium on Advanced Materials: Chemistry, Physics and Biology (ASAM-07)  2007/10
  • Friction and Lubrication of Bulk Hydrogels  [Invited]
    Jian Ping Gong
    The International Conference on Science of Friction  2007/09
  • 軟骨に匹敵する高弾性高強度ゲルの創製  [Invited]
    龔 剣萍
    第134回ゴム技術シンポジウム エラストマー補強の最前線  2007/09
  • ソフト&ウェットマターの摩擦と潤滑  [Invited]
    龔 剣萍
    ソフトインターフェース研究会  2007/09
  • Gel-a potential material as artificial soft tissue  [Invited]
    Jian Ping Gong
    GelSympo2007  2007/08
  • Cartilage-like tough gel with low friction  [Invited]
    Jian Ping Gong
    22th Japan-Korea Joint Symposium on Advanced Functional Polymers  2007/07
  • 生命科学時代が求める新材料―ソフト&ウェットマテリアルの創成  [Invited]
    龔 剣萍
    東京大学化学生命工学専攻談話会  2007/06
  • 高分子ゲル  [Invited]
    グン 剣萍
    高分子基礎講座(2007年)  2007/06
  • 生体軟組織から学んだ機能性ソフト&ウェトマターの創成とその物性  [Invited]
    龔 剣萍
    特定領域研究「非平衡ソフトマター物理学の創成:メソスコピック系の構造とダイナミクス(ソフトマター物理)」第2回領域会議  2007/06
  • 生体軟組織を目指した高分子ゲルの創成とその物性研究  [Invited]
    龔 剣萍
    SPring-8 講演会「女性研究者が手がける有機・高分子材料科学」  2007/06
  • 生命科学時代の新材料-強くて滑らかなゲル  [Invited]
    龔 剣萍
    新化学高分子ワークショップ  2007/02
  • 高強度・低摩擦ゲルの創製とその応用への展望  [Invited]
    龔 剣萍
    北海道大学-三井化学合同シンポジウム  2006/12
  • Cartilage-like Tough Gel with Low Friction  [Invited]
    Jian Ping Gong
    The First International Symposium on Polymer Materials Science  2006/12
  • 軟骨に匹敵する高強度・低摩擦ゲルの創製とその応用展開  [Invited]
    龔 剣萍
    ゲル研究会講座  2006/11
  • 生体機能材料としての高分子ゲルの新展開  [Invited]
    龔 剣萍
    第15回ポリマー材料フォーラム  2006/11
  • 龔 剣萍, 加々田 剛, 黒川 孝幸, 長田 義仁
    第55回高分子討論会  2006/09
  • Friction and Lubrication of Hydrogels  [Invited]
    Jian Ping Gong
    The 59th Divisional Meeting on Colloid and Interface Chemistry  2006/09
  • 高分子ゲル  [Invited]
    グン 剣萍
    高分子基礎講座(2006年)  2006/06
  • Friction reduction of hydrogel in surfactant solution  [Invited]
    Jian Ping Gong
    The 16th Symposiums on Surfactants in Solutions (SIS 2006)  2006/06
  • Anisotropic Growth of Actin-Polymer Complex  [Invited]
    Jian Ping Gong
    International Symposium on Polymer Physics (PP2006)  2006/06
  • 複合系秩序構造をもつ電解質ゲルの創製とその物性に関する研究  [Invited]
    龔 剣萍
    第55回高分子学会年次大会  2006/05
  • Elastic-Hydrodynamic Transition of Gel Friction  [Invited]
    Jian Ping Gong
    11th International Symposium on Colloidal and Molecular Electro-Optics  2006/05
  • Polymer-Protein Complexation and its Application as ATP-Driven Gel Machine  [Invited]
    Jian Ping Gong
    Hokkaido University-AIST collaborative conference"A Nanobiotechnology Research --The Perspective of Artificial Muscles" (The Third Conference on Artificial Muscles)  2006/05
  • ゲルの摩擦と潤滑  [Invited]
    龔 剣萍
    第51回トライボロジー先端講座―トライボロジー分野に貢献する新材料―  2006/02
  • 高強度・低摩擦ゲルの創製とその応用展開  [Not invited]
    SORST舩岡チームシンポジウム  2006
  • ゲルの階層構造から生体機能の秘密を探る  [Invited]
    龔 剣萍
    SORSTシンポジウム(4)  2005/11
  • 生物における水和潤滑  [Invited]
    龔 剣萍
    トライボロジー会議2005秋 シンポジウム(1)生物における水和潤滑  2005/11
  • Hydrogels with Excellent Mechanical Performance: An Approach to Understand the Secret of Cartilages  [Invited]
    Jian Ping Gong
    The International 21st Century COE Symposium on BINDEC Chemistry Network (BINDEC2005)  2005/10
  • ゲルの階層構造で解き明かす生体機能の秘密  [Invited]
    龔 剣萍
    バイオ・高分子シンポジウム  2005/09
  • Toughening of Gels  [Invited]
    Jian Ping Gong
    The 8th SPSJ International Polymer Conference (IPC 2005)  2005/07
  • Construction of cartilage-like strong hydrogels with low friction  [Invited]
    Jian Ping Gong
    Gordon Research Conference on Elastomers, Networks and Gels  2005/07
  • Surface Friction of Polymer Gels  [Invited]
    Jian Ping Gong
    The 11th International Conference on Organized Molecular Films  2005/06
  • 高強度低摩擦ゲル―機能性素材としての新展開  [Invited]
    龔 剣萍
    ゴム技術フォーラム月例会  2005/03
  • Hydrogels with Excellent Mechanical Performance: An Approach to Understand the Secret of Cartilages  [Invited]
    Jian Ping Gong
    International Symposium on Soft-Nanotechnology 2005 (ISSN2005)  2005/03
  • Tough Hydrogels with Double Network Structure  [Invited]
    Jian Ping Gong
    2005 Materials Research Society (MRS) Spring Meeting  2005/03
  • Molecular designing for construction of strong gels with low friction  [Invited]
    Jian Ping Gong
    Symposium on Nanostructure Control at Solid Surfaces for the Construction of Nano-molecular/bio Devices  2005/03
  • 筋肉タンパク自己組織化ゲルによるソフトナノマシンの創製  [Invited]
    龔 剣萍
    ナノテクノロジー分野4領域合同研究報告会(第3回「組織化と機能」研究報告会)  2005/01
  • Surface Friction of Gels-An Approach to Understand Biological Motion  [Invited]
    Jian Ping Gong
    Harima International Forum "Smart Polymer and Smart Surface in medicine and industry"  2005/01
  • ゲルで作る人工軟骨  [Invited]
    龔 剣萍
    スーパーサイエンスハイスクール  2004/12
  • ゲルで作る人工軟骨  [Invited]
    龔 剣萍
    COE市民キャンパス講座  2004/12
  • 高強度低摩擦ゲルの創製とその応用展開  [Invited]
    龔 剣萍
    高分子オイルゲル研究会  2004/10
  • Interfacial motion of soft and wet materials -an approach to understand biological motion  [Invited]
    Jian Ping Gong
    International Workshop on Bioengineering; Problems and Perspectives  2004/10
  • 高分子ゲルの科学  [Invited]
    龔 剣萍
    高分子学会北海道支部会員増強講演会  2004/09
  • 高分子の表面摩擦から生物運動の秘密を探る  [Invited]
    龔 剣萍
    関東若手会 2004ミニシンポジウム  2004/09
  • 超高強度ヒドロゲルの創成とその人工関節への応用展開  [Invited]
    龔 剣萍
    ゲルワークショップ イン 浜名湖  2004/08
  • 高分子ゲルの科学から生物運動の仕組みを探る  [Invited]
    龔 剣萍
    北大大学院共通講義「ナノテクノロジー・ナノサイエンス概論I―ナノマテリアル」  2004/07
  • ゲルの表面特性と機能から生物運動の秘密を探る  [Invited]
    龔 剣萍
    第51回高分子夏季大学  2004/07
  • ソフト&ウェットマテリアル-ゲルの機能と臨床応用  [Invited]
    龔 剣萍
    北海道大学医学部皮膚科学教室特別講演  2003/12
  • 高分子ゲルの表面摩擦から生物運動の秘密を探る  [Invited]
    龔 剣萍
    北海道大学公開講演会  2003/12
  • Role of Interfacial Interaction on the Sliding Friction of Gels  [Invited]
    Jian Ping Gong
    2nd France-Japan Workshop on “Structure, deformation and stimuli response of Polymer gels”  2003/11
  • Interfacial Motion of Soft and Wet Materials-An Approach to Understand Biological Motion  [Invited]
    Jian Ping Gong
    2nd International Symposium on “Reactive Polymers in Inhomogeneous Systems, in Melts and at Interfaces”  2003/09
  • ゲルの表面摩擦から生物運動の滑らかさの秘密を探る  [Invited]
    龔 剣萍
    第34回中部化学関係学協会支部連合秋季大会  2003/09
  • ソフト&ウエットマターの界面運動から探る生体運動の秘密  [Invited]
    龔 剣萍
    ソフトマターの物理学2003-普遍性と多様性  2003/07
  • Friction of Polymer Gels  [Invited]
    Jian Ping Gong
    12th European Carbohydrate Symposium  2003/06
  • 高分子ゲルの表面摩擦と次世代超低摩擦材料の創成  [Invited]
    龔 剣萍
    分子工学研究会  2003/04
  • ゲルの自己組織化で人工筋肉を作る  [Invited]
    龔 剣萍
    ジョイントフォラム「自己組織化とは何か-ナノテクノロジーを支えるもの-」  2003/03
  • ゲルの表面摩擦から解き明かす生物運動  [Invited]
    龔 剣萍
    第2回中国・四国支部高分子材料研究会(高分子学会50周年記念講演会)  2003/01
  • ゲルの表面摩擦と生物運動  [Invited]
    龔 剣萍
    COE早稲田大学シンポジウム  2003/01
  • 高分子ゲルのマクロ摩擦とミクロ構造―その現象と理論  [Invited]
    龔 剣萍
    第3回東京工業大学国際高分子基礎研究センターシンポジウム  2002/12
  • アクチン巨大会合体形成とその協調運動  [Invited]
    龔 剣萍
    ナノバイオ融合研究フォーラム  2002/12
  • Creation of Low Frictional Materials by Hydrogel and its Application as Artificial Cartilages  [Invited]
    Jian Ping Gong
    Fifth Annual Symposium JAPANESE-AMERICAN BECKMAN FRONTIERS OF SCIENCE  2002/12
  • ゲルの界面運動  [Invited]
    龔 剣萍
    マイクロアクチュエータと分子シンクロナイゼーションミニシンポジウム  2002/11
  • 高分子ゲルの表面摩擦特性-超低摩擦新素材の開発  [Invited]
    龔 剣萍
    高分子ゲル研究会講座  2002/11
  • 高分子ゲルを用いた超低摩擦材料の創成  [Invited]
    龔 剣萍
    高分子材料のトライボロジー研究会  2002/11
  • 高分子ゲルを用いたインテリジェント材料の創成  [Invited]
    龔 剣萍
    産官学技術移転フォーラム  2002/09
  • ゲルの摩擦と生物運動―物理化学からのアプローチ  [Invited]
    龔 剣萍
    ゲルワークショップイン河口湖  2002/08
  • Effect of Interfacial Interaction on Surface Friction of Polymer Gels  [Invited]
    Jian Ping Gong
    IUPAC World Polymer Congress  2002/06
  • Effect of Viscoelasticity of Polymer Network on Gels Surface Friction  [Invited]
    Jian Ping Gong
    International Symposium on Polymer Physics, PP’2002  2002/06
  • 生物から学んだゲルの表面摩擦とゲルの表面摩擦から分った生物運動  [Invited]
    龔 剣萍
    日本化学会第81春季年会  2002/03
  • Surface Friction of Polymer Gels  [Invited]
    Jian Ping Gong
    International Interdisciplinary Research Exchange Symposium  2002/03
  • 人工関節を目指した高分子ゲルの表面摩擦と超低摩擦材料の創製  [Invited]
    龔 剣萍
    高分子北海道支部会  2002/02
  • Investigation of Hydrogel Properties by Electronic Speckle Pattern Interferometry  [Invited]
    Jian Ping Gong
    Technology and Industry Trend of Photoelectron and Optical Communication  2001/10
  • 高分子ゲルの表面摩擦と超低摩擦材料の創製に関する研究  [Invited]
    龔 剣萍
    高分子討論会  2001/09
  • Surface Friction of Polymer Gels  [Invited]
    Jian Ping Gong
    Polymer Physics  2000/09
  • Surface Dynamic Property of Polymer Gel  [Invited]
    Jian Ping Gong
    6th Pacific Polymer Conference  1999/12
  • Friction of Polymer Gels and Potential Application as Artificial Cartilages  [Invited]
    Jian Ping Gong
    Global Chinese Symposium on Biomaterials and Controlled Release  1999/10
  • Surface Friction of Gels  [Invited]
    Jian Ping Gong
    5th International Symposium on Polymers For Advanced Technologies (PAT99)  1999/08
  • 高分子ゲルの表面動的特性  [Invited]
    龔 剣萍
    高分子学会北海道支部若手の会・ジョイントセミナー  1999/08
  • 高分子ゲルの表面摩擦特性  [Invited]
    龔 剣萍
    高分子材料自由討論会  1999/06
  • Surface Dynamics of Polymer Gel  [Invited]
    Jian Ping Gong
    10th Anniversary of National Key Laboratory of Polymer Physics of China  1999/04
  • ゲルの物理化学的特性と運動機能  [Invited]
    龔 剣萍
    ゲルワークショップ イン 湘南  1998/07
  • 高分子ゲルの動的特性  [Invited]
    龔 剣萍
    材料技術研究協会・表面改質研究会 第7回夏季セミナー  1998/07
  • 高分子ゲルの表面・界面特性  [Invited]
    龔 剣萍
    高分子学会年次大会  1998/05
  • インテリジェント ゲル  [Invited]
    龔 剣萍
    平成9年北海道工業技術研究所研究成果発表会  1997/06
  • Intelligent Gel  [Invited]
    Jian Ping Gong
    96' Chinese Young Scientists Symposium on Frontier Research of Polymer Materials  1996/09
  • 高分子ゲル粒子の秩序ー無秩序転移とその自発運動  [Invited]
    龔 剣萍
    第48回コロイドおよび界面化学討論会  1995/10
  • Biomimetic Motion of Polymer Gels by molecular Assembly Reaction  [Invited]
    Jian Ping Gong
    Symposium on Construction of Measures for Environmental Safety Using Performance of Advanced Polymer in East Asia  1995/10

MISC

Industrial Property Rights

Awards & Honors

  • 2019/04 Ministry of Education, Culture, Sports, Science and Technology 2019 The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology: Prizes for Science and Technology
     受賞した研究テーマ「強靭ゲルの創成とその強靭化原理の解明に関する研究 
    受賞者: Jian Ping Gong
  • 2018/03 Hokkaido University President's Award for Excellence in Research and Education for AY2017
     
    受賞者: Jian Ping Gong
  • 2014/07 Royal DSM The DSM Materials Sciences Award 2014
     
    受賞者: Jian Ping Gong
  • 2014/03 平成25年度北海道大学研究総長賞
     
    受賞者: グン 剣萍
  • 2011 日本化学会 第28回学術賞
  • 2011 The Chemical Society of Japan Award for Creative Work for 2011
  • 2006 高分子学会賞(科学)
  • 2006 The Award of the Society of Polymer Science, Japan
  • 2001 2001年Wiley高分子科学賞(物理学分野)
  • 2001 2001 Wiley Polymer Science Award (Physics)

Research Grants & Projects

  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
    Date (from‐to) : 2017/06 -2022/03 
    Author : グン 剣萍, 黒川 孝幸, 野々山 貴行
     
    1.レーザー刻印による自在な構造色応答を示すラメラゲル 脂質二分子膜と高分子ネットワークが交互に積層されたラメラゲルは、構造色を示し指圧程度の弱い力で膜間隔が変化し構造色が連続的に変化するソフトクリスタルである。このゲルに高強度レーザーでパターンを刻印すると膜が破壊され、そこへ高分子ネットワークと反応する物質を拡散させることで、局所的に高分子を改質することができる。この改質された高分子ネットワークは元のものと比べて、膨潤度が異なるため、レーザー刻印に沿った構造色の変化が観察され、ゲル材料全体を目的の形状に変形することができ、構造色ゲルのさらなる多機能化の技術として期待できる。 2.高温で1000倍以上弾性率がジャンプする相分離ゲル 一般的な高分子は低温で硬いガラス状態、高温で柔らかいゴム状態をとる。この性質とは逆の昇温過程におけるゴム-ガラス転移を示すゲルを初めて合成した。このゲルは、スピノ-ダル分解型の相分離を示し、ある温度以上では高分子濃厚相と希薄相に分離する。これまでの相分離ゲルは、強い相分離を達成できず、濃厚相は依然としてゴム状態であり弾性率の向上も大きくはなかった。本ゲルは、好熱菌のタンパク質が高温でも変性せずに構造を安定化させている機構を導入した。具体的には静電相互作用が疎水環境で増強されることを利用し、相分離後の高分子濃厚相(低含水率)にイオン結合が取り込まれることで、高分子間の相互作用が急激に上昇し、ガラス状態へ達する。その結果、弾性率が瞬時に3桁以上ジャンプする。この性質を利用して、事故の際に発生する摩擦熱を利用して硬くなるリアクティブプロテクターを試作し、優れた耐摩擦性を示した。
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)
    Date (from‐to) : 2017/05 -2022/03 
    Author : グン 剣萍, 黒川 孝幸, 野々山 貴行, キング ダニエル, 中島 祐
     
    本年度は主に、ハードマター相の犠牲結合が複合材料の強靭化に及ぼす効果を解明した。最初に、mmスケールの多様な二次元長方格子(犠牲結合)を設計し、高性能3Dプリンターによって作製した。次いで、高靱性の柔らかい材料をマトリックス相として格子と複合させ、巨視的なスケールでのダブルネットワーク複合体を創製した。二次元格子の骨格の太さを制御した実験より、引張試験における多段階の格子の破断(すなわち犠牲結合原理の発現)は、二次元格子の強度がマトリックスの強度を上回った場合に生じることが分かった。また格子の節の数を制御した実験より、節の数を増やすほど引張試験時における格子の破断イベント数が増えるために材料が強靭となるが、強靭性はある一定の値で頭打ちになることが分かった。さらに多様な材質による二次元格子を検討した結果、どのような材質を用いても複合材料は強靭になったことから、格子の化学的性質(例えば表面の接着性)は強靭化に大きな影響を及ぼさず、格子とマトリックスの力学物性の関係性が強靭化度合の決定の主要因であることが明らかとなった。 次いで、多様な二次元・三次元格子を設計し、格子のポアソン比を変化させた複合材料を創製した。骨格として、具体的には負のポアソン比を持つオーセチック構造や、正のポアソン比を持つハニカム構造などを用いた。引張試験結果より、複合材料の強度は格子とマトリックスのポアソン比のミスマッチが大きいほど高くなることが示唆された。偏光顕微鏡観察の結果、本現象は、複合材料の変形時、ポアソン比のミスマッチによりマトリックスが局所的に(巨視的な変形よりも)極めて大きく変形することによって引き起こされていることが示唆された。また、ポアソン比のミスマッチによりマトリックスが(通常では起こりえない)体積変形を強いられることも原因の1つではないかと考えられ、現在検証を進めている。
  • The Cabinet Office:Impulsing Paradigm Change through Disruptive Technologies Program (ImPACT)
    Date (from‐to) : 2014/10 -2018/12 
    Author : Gong Jian Ping
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)
    Date (from‐to) : 2012/05 -2017/03 
    Author : Gong Jian Ping, NONOYAMA Takayuki, SUN Taolin
     
    Gels have been anticipated as tissue-like functional materials, but generally they are mechanically too weak to be applied widely. On the other hand, recently our group has proposed "sacrificial bond principle", where toughness of gels can be effectively improved by introducing weak and brittle bonds into soft and stretchable networks. In this project, we have created a series of extremely tough gels using this principle, e.g., variants of double network gels featuring covalent sacrificial bonds, polyampholyte gels containing ionic sacrificial bonds, and phase-separated polyacrylamide gels exhibiting super toughness based on solvophobic sacrificial bonds. We have also succeeded in adding functions corresponding to chemical species of sacrificial bonds to the tough gels, e.g., self-healing properties to polyampholyte gels and bioactivity to double network gels containing biopolymers. Through these studies, we have confirmed generality and diversity of sacrificial bond principle.
  • Japan Science and Technology Agency:Advanced Low Carbon Technology Research and Development Program
    Date (from‐to) : 2011/10 -2012/09 
    Author : GONG Jian Ping
  • 「犠牲結合原理」の普遍性の証明と多様な犠牲結合による高靭性ゲルの創製
    基盤研究(A)
    Date (from‐to) : 2012/04 -2012/05 
    Author : グン 剣萍
  • Material Innovation for the Age of Life Science-Creation of Soft and Wet Materials
    Grant-in-Aid for Specially Promoted Research
    Date (from‐to) : 2006/06 -2011/03 
    Author : グン 剣萍
  • ATP駆動型ソフト&ウェット運動素子の開発と応用
    Japan Science and Technology Agency:Solution Oriented Research for Science and Technology (SORST), JST
    Date (from‐to) : 2004/11 -2007/03 
    Author : GONG Jian Ping
     
    これまでにホタテ貝筋肉由来のアクチン・ミオシンを自己集合させながら化学架橋を施すことにより、ATPを加えながら相互作用させると滑り運動を示すことを明らかにした。 そこで、本課題ではこの成果を発展させて、ATPで駆動する人工運動素子の創製をめざす。
  • Creation of Soft & Wet Artificial Muscles and Their Application as Biomotion Systems
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Creative Scientific Research
    Date (from‐to) : 2002 -2006 
    Author : OSADA Yoshihito, GONG Jian Ping, YASUDA Kazunori, YAGI Toshirou, YAMAMOTO Masafumi, KAWABATA Kazushige
     
    (I) Synthesis of hydrogel as soft and wet artificial muscles By introducing the double network structure into hydrogel, we succeeded in obtaining the hydrogel with extra-ordinary high mechanical toughness (Fracture strength of about several Mpa). In addition, by changing the inhomogeous structure of the first network from several 10nm to micrometer, we succeeded in controlling the mechanical behavior of the DN gel from brittle-like to ductile-like. The ductile-like DN gel exhibits an elongation as high as 20 times before failure. To apply this gel as artificial cartilage, we further introduced the graft structure to the DN gel surface and succeeded in obtaining the gel with a fracture stress of several 10MPa, fracture energy of 1000 J/cm^2, and sliding friction coefficient of 10^<-5>〜10^<-4>. (II) Application of hydrogel as substitutes of bio-organs To apply the gel with excellent mechanical properties as artificial cartilage, wear property, bio-durability and biocompatibility were investigated. Several kinds of DN gels sustained cyclic pin-on-flat test for one million times with a total sliding distance of 50 km, and showed a wearing rate of 10^<-8>-10^<-7>mm^3/Nm. This wear resistance is higher than that of the high density polyethylene (wearing rate of 10^<-7>mm^3/Nm). Implantation test of DN gel in the rabbits showed that among several kinds of DN gels, the PAMPS/PDMAAm DN gel was the most suitable for bio-durability. Moreover, it was found that the gel showed a good biocompatibility when artificial cartilage made of PAMPS/PDMAAm was implanted in the articular joints of rabbits. Furthermore, we discovered that normal cartilage was regenerated in situ when the PAMPS/PDMAA gel was imbedded into the articular joint several mm from the surface as artificial cartilage. This great discovery will lead to a completely new method to repair the damaged cartilage in situ.
  • Creation of Cartilage-Like Hydrogels with High Toughness and Low Friction
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2002 -2005 
    Author : GONG Jian Ping, OSADA Yoshihito
     
    Our study shows that hydrogel shows a low surface sliding friction. Especially the presence of polyelectrolyte brushes on a hydrogel surface can effectively reduce the surface sliding frictional coefficient to a value as low as 10^<-4>. The low friction of gel should have enabled the gel to find a wide application in many fields where low friction is required, such as articular cartilage, semi lunar cartilage. However, conventional hydrogels, especially polyelectrolyte gels, are mechanically too weak to be practically used in any stress or strain bearing applications. A hydrogel usually breaks down under a compressive stress not higher than 0.1 MPa. However, an articular cartilage, especially those of kneels and hips, sustains a daily compression of several to decades MPa, exhibits a friction coefficient as low as 10^<-3> over a wide range of sliding velocity. The mechanical weakness has hindered not only the extensive application of hydrogels as an industrial and biomedical materials, but also the fundamental researches on the friction behavior of gel under a pressure higher than MPa where desolvation might occur. We discovered a general method to obtain very strong hydrogels containing 60-90 % water by inducing a double-network (DN) structure for various combinations of hydrophilic polymers. The DN hydrogel can exhibit fracture strength as high as a few to several tens of megapascals, that is, 100 kg/cm^2). Based on these researches, we further developed a novel material, a high strength DN gel containing either a weakly cross-linked 3^ network or non-cross-linked 3^ linear chains which shows a fracture strength as high as 9 MPa and frictional coefficient μ as low as 10^<-4>. The gel with both a high strength and an extremely low surface friction would find wide applications not only in industry but also in biomedical field, for example, as substitutes of articular cartilage or other bio-tissues.
  • Japan Science and Technology Agency:Precursory Research for Embryonic Science and Technology (PRESTO type), JST
    Date (from‐to) : 2001/10 -2004/10 
    Author : GONG Jian Ping
     
    本研究は筋肉蛋白であるアクチンとミオシンを基本素材として用い、それらをそれぞれ自己組織化させると同時に、酵素活性を生かしながら化学架橋することにより、ATPで駆動するソフトナノマシンを創製することを目指します。この研究によって、これまでにないATPで駆動する生体適応性ソフトマニュピレータやソフトアクチュエータの実現が期待できます。
  • Construction of Biomimetic Moving Systems Using Polymer Gels
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Specially Promoted Research
    Date (from‐to) : 1997 -2001 
    Author : OSADA Yoshihito, GONG Jian ping
     
    In order to create biomimetic motility systems, polymer gels have been employed using their reversible size and shape change, thereby realizing the motion by integrating the deformation on a molecular level. Along this line, several kinds of artificial soft machines have been constructed using synthetic polymer gels, such as gelooper (gel-looper), gelf (gel golf), gel valves, chemical motor, shape memory gel, artificial muscle, artificial heart. Motivated by these research results, we have succeeded in obtaining hydrogels with a high mechanical strength as 10 MPa sustaining more than millions of continuous wearing test with little wearing due to their extremely low frictional coefficient. These gels might open new era of soft & wet materials for substituting articular cartilage and other tissues of human body. By comparing the behaviors of gel machine with the solid machine, the specific features of the soft and wet machine have been elucidated. For example, if a gel has free dangling charged polymer chains on its surface, the frictional coefficient becomes as low as 10^<-4>, which is lower than that of animal articular cartilage. We have successfully created an ATP fueled soft gel machine reconstructed from muscle proteins of actin and myosin. Chemically cross-linked actin gel filaments, several thousand times the volume of native actin filaments (F-actin) move along a chemically cross-linked myosin fibrous gel (1 cm long and 50 μ m in diameter) with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. The muscle protein-gel demonstrates that one can reconstruct a soft machine fueled by chemical energy by using actin and myosin molecules as elementary elements.
  • イオン性高分子ゲルの電導特性と網目の役割
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 1996 -1998 
    Author : グン 剣萍, 長田 義仁
     
    高分子ゲルの収縮挙動、伝導度、誘電率をさまざまの電場を印加することにより、実験的に解析した。また、その機構を3次元網目モデルを用いた計算により理論的に検討した。特に高分子網目の結び目(ジョイント)に着目し、これが静電ポテンシャルの分布・イオンの輸送・伝導度・高分子網目と溶媒やイオン間の相互作用にどのような役割を果たしているかを明らかにした。このように系統的な実験と新しいモデルに基づいた理論計算の結果をあわせることによって次の基礎的知見が得られた。 1)ゲルの高分子網目中の低分子イオン・溶媒の物質輸送過程 2)高分子網目の相互作用と応答のダイナミックス
  • 高分子ゲルにおける超構造形成とその制御
    Japan Society for the Promotion of Science:Grant-in-Aid for Scientific Research on Priority Areas
    Date (from‐to) : 1997 -1997 
    Author : グン 剣萍
  • 高分子ゲルにおける超構造形成とその制御
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Priority Areas
    Date (from‐to) : 1996 -1996 
    Author : ぐん 剣萍, 長田 義仁
     
    1)アクリル酸メチルと種々の長鎖アルキル基を有するアクリル酸エステルの共重合体ゲルを合成し、その構造を広角・小角X線回析装置を用いて解析した。昨年度研究したアクリル酸共重合ゲルの結果と比較しながら、構造形成における疎水性相互作用と水の役割を明らかにした。(長田義仁) 2)熱転移解析装置を用い、共重合組成の違うゲルについて秩序-無秩序転移温度・転移熱などを測定し、熱力学的諸量と超構造との対応関係を明らかにした。特に、橋かけ密度が超構造形成および力学特性に及ぼす影響について考察した。 3)ゲルの静電ポテンシャル場を理論計算によってシミュレーションし、極性側鎖・水分子間の相互作用と超構造形成過程との関係を理論的に解析した。
  • 高分子ゲルにおける超構造形成とその制御
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Priority Areas
    Date (from‐to) : 1995 -1995 
    Author : ぐん 剣萍, 安永 秀計, 長田 義仁
     
    平成7年度 1)アクリル酸と長鎖アルキル基を有するアクリル酸エステルの共重合体ゲルを合成した。得られたゲルの構造を広角・小角X線回折装置を用いて解析し、超構造形成における疎水性の役割を評価した。(長田) 2)ゲル中の水の融点・転移熱・誘電率などをDSC・購入したの微少熱量測定装置・LCZメータによって測定し、ゲルの網目によってつくられる静電ポテンシャルの場における水の諸特性変化を実験的に評価した。同時にゲルの静電ポテンシャル場をコンピュータを用いた理論計算によってシミュレートし、極性側鎖・水分子間の相互作用と超構造形成過程との関係を理論的に解析した。(ぐん)

Educational Activities

Teaching Experience

Campus Position History

  • 2014年5月15日 
    2015年3月31日 
    総長補佐
  • 2014年5月15日 
    2017年3月31日 
    研究戦略室室員
  • 2015年4月1日 
    2017年3月31日 
    総長補佐

Position History

  • 2014年5月15日 
    2015年3月31日 
    総長補佐
  • 2014年5月15日 
    2017年3月31日 
    研究戦略室室員
  • 2015年4月1日 
    2017年3月31日 
    総長補佐


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