Researcher Profile and Settings

Master

Affiliation (Master)

• Research Institute for Electronic Science　Biology and Life Sciences

Affiliation (Master)

• Research Institute for Electronic Science　Biology and Life Sciences

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Profile and Settings

Degree

• PhD（Tokyo Institute of Technology）

Profile and Settings

• Name (Japanese)

  Mitomo

• Name (Kana)

  Hideyuki

• Name

  200901032624814700

Achievement

Research Areas

• Nanotechnology/Materials / Biochemistry
• Nanotechnology/Materials / Nanomaterials
• Nanotechnology/Materials / Polymer materials

Research Experience

• 2017/09 - Today Hokkaido University Research Institute for Electronic Science Associate Professor
• 2011/04 - 2017/08 Hokkaido University Research Institute for Electronic Science assistant Professor
• 2009/06 - 2011/03 Hokkaido University Research Institute for Electronic Science
• 2007/06 - 2009/05 Lehigh University Post Doctoral Fellow
• 2007/04 - 2007/05 Tokyo Institute of Technology

Education

• 2002/04 - 2007/03  東京工業大学大学院
• 1998/04 - 2002/03  Tokyo Institute of Technology  School of Bioscience and Biotechnology

Published Papers

• Plasmonic circular dichroism-based metal ion detection using gold nanorod-DNA complexes.

  Yali Shi, Satoshi Nakamura, Hideyuki Mitomo, Yusuke Yonamine, Guoqing Wang, Kuniharu Ijiro

  Chemical communications (Cambridge, England) 60 (82) 11794 - 11797 2024/10/10 

  We report that complexes formed between gold nanorods (AuNRs) and metal-mediated DNA exhibit plasmonic circular dichroism (CD) signals up to ∼400 times stronger than the molecular CD signal of DNA. This substantial enhancement enables the detection of metal ions, offering a promising approach to analytical applications in chiral biochemistry.
• Ultrasensitive Surface-Enhanced Raman Scattering Platform for Protein Detection via Active Delivery to Nanogaps as a Hotspot

  Tianxu Gao, Takehiro Yachi, Xu Shi, Rina Sato, Chikara Sato, Yusuke Yonamine, Kiyoshi Kanie, Hiroaki Misawa, Kuniharu Ijiro, Hideyuki Mitomo

  ACS Nano 1936-0851 2024/08/02
• Hierarchical Au Nanoflowers Formed in an Ionic Liquid/Water System for Bacterial Inhibition

  Huiling Yin, Qingsong Zhang, Shengchao Hu, Xun Sun, Lin Peng, Huijie Zhao, Qing Kong, Hideyuki Mitomo, Yasutaka Matsuo, Kuniharu Ijiro, Guoqing Wang

  ACS Applied Nano Materials 2574-0970 2024/07/17
• Assembly/disassembly control of gold nanorods with uniform orientation on anionic polymer brush substrates

  Jingyan Yang, Yu Sekizawa, Xu Shi, Kuniharu Ijiro, Hideyuki Mitomo

  Bulletin of the Chemical Society of Japan 0009-2673 2024/07/10 

  Abstract Sophisticated control of the spatial arrangement of gold nanorods provides significant advantages in the design of plasmonic systems. However, dynamic modulation of the gold nanorod spatial arrangements remains challenging. Here, we present a novel strategy for dynamic control of thermo-responsive gold nanorods with uniform alignment on a solid substrate using polymer brushes. In this system, cationic and thermo-responsive gold nanorods were immobilized into anionic polymer brushes via moderate electrostatic interactions, providing vertically aligned gold nanorod arrays. Upon heating, the gold nanorods were assembled while maintaining their vertical orientation within the polymer brushes. They returned to the original state upon cooling, indicating reversible assembly/disassembly. It is noticeable that this system exhibits rapid changes in nanostructure arrangement even when immobilized in the polymer brush substrate on a solid substrate rather than those dispersed in solution. Importantly, the gold nanorods showed good adhesion stability in polymer brushes without any significant detachment during washing and thermal cycling processes but performed assembly formation even at largely separated conditions, indicating the traveling of considerable distances similar to the lateral diffusion of membrane proteins in cell membranes. In addition to providing unprecedented control over gold nanorod spatial configurations, our approach introduces a versatile platform for developing advanced plasmonic devices.
• π-extended porphyrin-based near-infrared photosensitizers for mitochondria-targeted photodynamic therapy

  Hanjun Zhao, Rina Naganawa, Yuma Yamada, Yasuko Osakada, Mamoru Fujitsuka, Hideyuki Mitomo, Yukiko Miyatake, Hideyoshi Harashima, Vasudevanpillai Biju, Yuta Takano

  Journal of Photochemistry and Photobiology A: Chemistry 449 115397 - 115397 1010-6030 2024/04 [Refereed]
  
• Spatially Uniform and Quantitative Surface-Enhanced Raman Scattering under Modal Ultrastrong Coupling Beyond Nanostructure Homogeneity Limits

  Yoshiki Suganami, Tomoya Oshikiri, Hideyuki Mitomo, Keiji Sasaki, Yen-En Liu, Xu Shi, Yasutaka Matsuo, Kuniharu Ijiro, Hiroaki Misawa

  ACS Nano 18 (6) 4993 - 5002 1936-0851 2024/02/01 [Refereed]
  
• Dynamic Orientation Control of Gold Nanorods in Polymer Brushes by Their Thickness Changes for Plasmon Switching

  Yu Sekizawa, Yuka Hasegawa, Hideyuki Mitomo, Chisato Toyokawa, Yusuke Yonamine, Kuniharu Ijiro

  Advanced Materials Interfaces 2196-7350 2024/01/10 [Refereed]
   

  Abstract Gold nanorods (AuNRs) have unique optical properties such as transverse and longitudinal localized surface plasmon resonance (T‐ and L‐LSPR). As the L‐LSPR absorption depends on the angle of the AuNRs to incident light and polarization, orientational control of AuNRs is a crucial issue. In spite of various techniques to control AuNR orientation, dynamic orientation tuning on a solid substrate remains challenging. Herein, dynamic changes are demonstrated in AuNR orientation in the anionic polymer (DNA) brushes via control of their thickness by salt concentration. AuNRs vertically align toward the substrates when their thickness exceeds the AuNR length. Once their thickness becomes shorter than the AuNR length, the attached AuNRs begin to tilt. The tilt reaches a maximum level close to horizontal when the thickness decreases to half that of the AuNR length. The dynamic control between the vertical (uniform) and tilted (random) orientation of the AuNRs showed not only absorption intensity changes in L‐LSPR but also the switching of side‐by‐side plasmon coupling. The polymer brush‐based system affords a novel platform for the stimuli‐responsive control of AuNR orientation on the substrates via changes in the thickness of polymer brushes for actively tunable plasmonic substrates.
• Fair surface modification with mixed alkanethiols on gold nanoparticles through minimal unfair ligand exchange

  KUN XIONG, Masaharu Nagayama, Kuniharu Ijiro, Hideyuki Mitomo

  Nanoscale Advances 2516-0230 2024 

  Ligand exchanges between alkanethiols at gold surfaces were demonstrated as a cause of unfair surface modification of gold nanoparticles with mixed alkanethiols. Kinetic analyses suggested an importance of moderate reaction conditions.
• Size Segregation of Gold Nanoparticles into Bilayer-like Vesicular Assembly

  Jinjian Wei, Yi Yu, Yasutaka Matsuo, Liang Zhang, Hideyuki Mitomo, Yuqin Chen, Kuniharu Ijiro, Zhide Zhang

  Langmuir 39 (49) 17939 - 17946 0743-7463 2023/12/01 [Refereed]
  
• DNA-Functionalized Silver Nanoparticles in an Alcoholic Solvent for Environment-Dictated Multimodal Actuation

  Li Kong, Luyang Wang, Yali Shi, Lin Peng, Xingguo Liang, Guoqing Wang, Hideyuki Mitomo, Tohru Takarada, Kuniharu Ijiro, Mizuo Maeda

  ACS Applied Nano Materials 5 (8) 10321 - 10330 2574-0970 2022/08/26 [Refereed]
  
• Three-dimensional structure determination of gold nanotriangles in solution using X-ray free-electron laser single-particle analysis

  Miki Nakano, Osamu Miyashita, Yasumasa Joti, Akihiro Suzuki, Hideyuki Mitomo, Yoshiya Niida, Ying Yang, Hirokatsu Yumoto, Takahisa Koyama, Kensuke Tono, Haruhiko Ohashi, Makina Yabashi, Tetsuya Ishikawa, YOSHITAKA BESSHO, Kuniharu Ijiro, Yoshinori Nishino, Florence Tama

  Optica 2022/06/06 [Refereed]
  
• Thermo-Responsive Silver Nanocube Assembled Films

  Hideyuki Mitomo, Chie Takeuchi, Ryo Sugiyama, Kaoru Tamada, Kuniharu Ijiro

  Bulletin of the Chemical Society of Japan 95 (5) 771 - 773 0009-2673 2022/05 [Refereed]
   

  Cube-structured silver nanoparticles (AgNCs) were synthesized and modified with oligo(ethylene glycol) (OEG)-attached alkane-thiol ligands. They showed thermo-responsive color changes dispersed in water and also good dispersibility in CHCl3. They formed well-packed assembled structures at the airwater interface. AgNC assembled films also showed a strong plasmonic property and thermo-responsiveness.
• Hysteresis in the Thermo-Responsive Assembly of Hexa(ethylene glycol) Derivative-Modified Gold Nanodiscs as an Effect of Shape

  Joshua Chidiebere Mba, Hideyuki Mitomo, Yusuke Yonamine, Guoqing Wang, Yasutaka Matsuo, Kuniharu Ijiro

  NANOMATERIALS 12 (9) 2022/05 [Refereed]
   

  Anisotropic gold nanodiscs (AuNDs) possess unique properties, such as large flat surfaces and dipolar plasmon modes, which are ideal constituents for the fabrication of plasmonic assemblies for novel and emergent functions. In this report, we present the thermo-responsive assembly and thermo-dynamic behavior of AuNDs functionalized with methyl-hexa(ethylene glycol) undecane-thiol as a thermo-responsive ligand. Upon heating, the temperature stimulus caused a blue shift of the plasmon peak to form a face-to-face assembly of AuNDs due to the strong hydrophobic and van der Waals interactions between their large flat surfaces. Importantly, AuNDs allowed for the incorporation of the carboxylic acid-terminated ligand while maintaining their thermo-responsive assembly ability. With regard to their reversible assembly/disassembly behavior in the thermal cycling process, significant rate-independent hysteresis, which is related to their thermo-dynamics, was observed and was shown to be dependent on the carboxylic acid content of the surface ligands. As AuNDs have not only unique plasmonic properties but also high potential for attachment due to the fact of their flat surfaces, this study paves the way for the exploitation of AuNDs in the development of novel functional materials with a wide range of applications.
• Core-Gap-Shell Nanoparticles@Polyaniline with TunablePlasmonic Chiroptical Activities by pH and Electric Potential Dual Modulation

  Han Lin, Hideyuki Mitomo, Yusuke Yonamine, Zhiyong Guo, Kuniharu Ijiro

  CHEMISTRY OF MATERIALS 34 (9) 4062 - 4072 0897-4756 2022/05 [Refereed]
   

  The emerging concept of tunable plasmonicchirality is mostly observed as a reconfigurable behavior or afeature of complex chiral plasmonic assemblies. For discretecolloidal particles, it is challenging to achieve reversible tunabilityor a transient response with regard to chiroptical activities,particularly in the visible or near-infrared region. Herein, wedemonstrate a stimulus-responsive system based on chiralmolecule-achiral plasmonic nanoparticles coated with polyaniline(PANI) as a variable dielectric layer, in whichL-/D-cysteinemolecules are introduced between the gold core and the shell as astatic chiral source, allowing the chiral transfer effect to be greatlyamplified by the hotspot gap of sub-monomolecular thickness. By taking advantage of the responsive properties to either pH or theelectric potential dual stimuli of PANI, which also provides a stable and real-time switchable dielectric environment for the wholesystem, dynamic tuning of the plasmon and its induced chiroptical activities of core-gap-shell nanoparticles@PANI were preciselyobtained. This well-defined design provides an open platform forflexible and rational tailoring of plasmonic cores, chiral molecules,and variable dielectrics to chiroptical needs, which is important for realizing applications in chemical sensing, chiral nanocatalysis,enantioselective separations, and novel optical devices
• Self-assembly of Gold Nanorods into a Highly Ordered Sheet via Electrostatic Interactions with Double-stranded DNA

  Satoshi Nakamura, Hideyuki Mitomo, Shigeaki Suzuki, Yu Torii, Yu Sekizawa, Yusuke Yonamine, Kuniharu Ijiro

  CHEMISTRY LETTERS 51 (5) 529 - 532 0366-7022 2022/05 [Refereed]
   

  Assemblies of cationic gold nanorods (AuNRs) via electrostatic interactions with double-stranded (ds) DNA were investigated in solution and after evaporation as a cast-film. Interestingly, moderately positively charged AuNRs assembled with dsDNA provided a monolayer sheet with an ordered alignment resembling a two-dimensional (2D) smectic structure during solvent evaporation.
• Visualization of DNA replication in single chromosome by stable isotope labeling.

  Kosuke Nagata, Ken-Ichi Bajo, Hideyuki Mitomo, Ryosuke Fujita, Ryota Uehara, Kuniharu Ijiro, Hisayoshi Yurimoto

  Cell structure and function 46 (2) 95 - 101 0386-7196 2021/09/25 [Refereed]
   

  Among the inheritance of cellular components during cell division, deoxyribonucleic acid (DNA) and its condensate (chromosome) are conventionally visualized using chemical tag-labeled nucleotide analogs. However, associated mutagenesis with nucleotide analogs in the visualization of chromosomes is cause for concern. This study investigated the efficiency of using stable isotope labels in visualizing the replicating cultured human cell-chromosomes, in the absence of analog labels, at a high spatial resolution of 100 nm. The distinct carbon isotope ratio between sister chromatids reflected the semi-conservative replication of individual DNA strands through cell cycles and suggested the renewal of histone molecules in daughter chromosomes. Thus, this study provides a new, powerful approach to trace and visualize cellular components with stable-isotope labeling.Key Words: stable isotope, chromosome replication, semi-conservative replication, imaging, mass spectrometry.
• Vesicle Formation by the Self-Assembly of Gold Nanoparticles Covered with Fluorinated Oligo(ethylene glycol)-Terminated Ligands and Its Stability in Aqueous Solution

  Jinjian Wei, Xiaoying Huang, Liang Zhang, Yuqin Chen, Kenichi Niikura, Hideyuki Mitomo, Kuniharu Ijiro, Zhide Zhang

  LANGMUIR 37 (32) 9694 - 9700 0743-7463 2021/08 [Refereed]
   

  Water-stable gold nanoparticle vesicles (GNVs) with hollow interiors have attracted attention due to their great potential for biological applications; however, their preparation through the self-assembly approaches has been restricted due to the limited understanding of their critical mechanistic issues. In this paper, we demonstrate that a fluorinated tetra (ethylene glycol) (FTEG)-terminated tetra (ethylene glycol) (EG4), namely, FTEG-EG4, ligand can self-assemble with gold nanoparticles (5 and 10 nm) into GNVs with a hollow structure in THE due to the solvophobic feature of the ligand. Time-dependent studies showed that the GNVs with a closely packed surface derived from the incomplete and irregular GNVs, but not through the fusion of the GNV precursors. After dialysis in water, the assemblies retained vesicular structures in water, even though GNVs aggregated together, which was initiated by the hydrophobic interactions between the FTEG heads of the surface ligands on GNVs. This study provides a new insight into the design of novel small surface ligands to produce water-stable GNVs for biological applications.
• Non-origami DNA for functional nanostructures: From structural control to advanced applications

  Lan Zhang, Xingyi Ma, Guoqing Wang, Xingguo Liang, Hideyuki Mitomo, Andrew Pike, Andrew Houlton, Kuniharu Ijiro

  NANO TODAY 39 1748-0132 2021/08 [Refereed]
   

  The revolutionary idea that DNA can play a non-biological role in a material world has indeed become today's reality. Although much attentions have recently been paid to "structural DNA nanotechnology" centered on DNA origami, due to the need for DNA computation, hybridization and modification that are usually not easily accessed, reproduced, or manipulated, preparation of nanostructures using DNA origami may have yet set a threshold for researcher to advance their fields with functional nanomaterials. It is suggested that, consisting of a few nucleotides (base pairs), or readily obtained by a simple procedure, non-origami DNA itself has sufficiently rich chemical functionality, and afford sequence-programmed growth of hybrid nano-architectures made of DNA and interactive materials with base-resolution control, and that the potential of non-origami DNA in building functional nanostructures has been underestimated. We have investigated an impressive number of fundamental and application-orientated studies in the late few years, and been preparing the review of the state of research in various subdisciplines of functional nanostructures based on non-origami DNA, which involve fundamental interactions of DNA-inorganic species, DNA nanofabrication, electronic nanodevices, functional metal nanoparticles and chiral nanostructures as well. Applications for these nanostructures have been covered in fields ranging from plasmonic biosensing and electrical nanodevices to optical bioimaging and photocatalysis. In this review, we will start with the fundamentals in DNA-based nanofabrication, including structure, characteristics and handling of DNA. Then, the capability of morphological control by simple DNA molecules, the resultant nanostructures and novel properties will be discussed and compared. Particularly, we emphasized the potential of single DNA molecules in templating the growth of nanostructures with different compositions, such as electrical polymer/metal nanowires, plasmonic nanostructures, fluorescent quantum dots and chiral silica nanostructures. Furthermore, the advanced applications of the non-origami DNA-based functional nanostructures in a range of fields will be figured out, including nanoelectronics, therapeutics and photocatalysis. Finally, conclusions will be drawn, and perspectives will be given. This review should be important for the development of DNA nanotechnology and DNA-based nanomaterials in the next decade, and creation of new nanomaterials based on simple DNA molecules, and their expanded applications as well. (c) 2021 The Authors. Published by Elsevier Ltd. CC_BY_NC_ND_4.0
• Molecular configuration-mediated thermo-responsiveness in oligo(ethylene glycol) derivatives attached on gold nanoparticles dagger

  Kun Xiong, Hideyuki Mitomo, Xueming Su, Yier Shi, Yusuke Yonamine, Shin-ichiro Sato, Kuniharu Ijiro

  NANOSCALE ADVANCES 3 (13) 3762 - 3769 2516-0230 2021/07 [Refereed]
   

  Biomolecular systems actively control their local environment on a sub-nm scale via changes in molecular configuration from their flexible structures and derive emergent functions. Although this functional emergence based on local environmental control is attracting a great deal of attention in chemistry, it remains challenging to realize this artificially. Herein, we report the tuning of the thermo-responsive properties of oligo(ethylene glycol) (OEG) derivatives attached on gold nanoparticles via local environmental control not only by the hydrophobic moiety at their terminus but also by their molecular configuration. OEG-attached alkane thiol-modified AuNPs showed thermo-responsive assembly/disassembly in water through the hydration/dehydration of the OEG portions in a manner dependent both on the hydrophobicity at their terminus and the surface curvature of the core nanoparticles. Further, the assembly temperature (T-A) was also tuned by ligand mixing with a non-thermo-responsive ligand with a shorter OEG length. Molecular dynamics simulations show that the distribution of the hydrophobic terminus in the normal direction along the gold surface varied in accordance with the surface curvature, indicating variations in molecular configuration. It is expected that a bent configuration could accelerate the thermo-responsiveness of OEG by allowing them greater accessibility to the hydrophobic terminus. Experimental and simulation results support the notion that local OEG density tuning by surface curvature or ligand mixing with a different OEG length leads to different degrees of accessibility to the hydrophobic terminus via changes in molecular configuration, promoting local environmental control-directed assembly temperature tuning.
• Controlled Nanostructures Fabricated by the Self-Assembly of Gold Nanoparticles via Simple Surface Modifications

  Hideyuki Mitomo, Kuniharu Ijiro

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 94 (4) 1300 - 1310 0009-2673 2021/04 

  This review introduces recent advances in the fabrication of metal nanostructures via self-assembly with a particular focus on our studies. As nanostructures, in particular metal nanostructures, show unique properties which are not observed in bulk materials, the development of nanofabrication techniques has attracted much attention in the research fields of nanoscience and nanotechnologies. From the viewpoint of biomimetics, it is imagined that sophisticated structures with spatiotemporal controllability on a nanoscale are crucial. Thus, much effort has been paid to the fabrication of 3- and 4-dimensional metal nanostructures. Although there are various approaches, the most promising is the self-assembly of gold nanoparticles (AuNPs) and their combination with soft matters. To obtain further controlled nanostructures for better properties, their systems have become more and more complex. For future expan- sion of these technologies, simplified systems are preferable for refining them based on clear mechanisms. From this point of view, we have worked on the self-assembly of AuNPs modified with oligo(ethylene glycol) (OEG)-derivatives as a small, simple molecule with a definite chemical structure and fabricated 3D hollow capsule structures and reversibly changeable structures responding to certain stimuli in solution and on/in soft matters. These results are expected to support the creation of novel nanodevices.
• Assembly and Active Control of Nanoparticles using Polymer Brushes as a Scaffold

  Satoshi Nakamura, Hideyuki Mitomo, Kuniharu Ijiro

  Chemistry Letters 50 (2) 361 - 370 0366-7022 2020/11/25 [Refereed]
   

  Abstract Inorganic nanoparticles are an attractive material that shows unique properties that differ from their bulk counterparts. Assembly of nanoparticles with soft materials is an effective approach to leverage their unusual properties for the fabrication of functional devices. Among the various soft materials, polymer brushes are expected to offer exciting opportunities due to their unique conformational properties. Here, we review research progress in the assembly and active control of gold nanoparticles with polymer brushes as a scaffold.
• Reversible changes in the orientation of gold nanorod arrays on polymer brushes

  Yu Sekizawa, Hideyuki Mitomo, Mizuki Nihei, Satoshi Nakamura, Yusuke Yonamine, Akinori Kuzuya, Takehiko Wada, Kuniharu Ijiro

  NANOSCALE ADVANCES 2 (9) 3798 - 3803 2516-0230 2020/09 [Refereed]
   

  Nanoparticles exhibit a number of unique properties such as localized surface plasmon resonance (LSPR). As this LSPR is sensitive to geometrical or spatial conditions, the arrangement of nanoparticles, in particular the active arrangement of plasmonic structures, is an important issue. In this study, gold nanorod (GNR) arrays were prepared by GNR attachment on anionic polymer (DNA) brushes via electrostatic interactions and their stimuli-responsive changes in orientationwere investigated. As a result, the orientation of GNR arrays on DNA brushes reversibly changed by the modulation of electrostatic interactions between GNRs and polymers via changes in the solution pH. As these extensive GNR arrays are prepared via easy bottom-up processes, GNR surface properties are easily tuned by simple modification, and DNAs could be replaced with various synthetic polymers, we believe that this study will lead to the development of nextgeneration materials and devices with actively tunable structures.
• Micro-liquid enclosure array and its semi-automated assembling system for x-ray free-electron laser diffractive imaging of samples in solution

  Takashi Kimura, Akihiro Suzuki, Ying Yang, Yoshiya Niida, Akiko Nishioka, Masashi Takei, Jinjian Wei, Hideyuki Mitomo, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro, Kensuke Tono, Makina Yabashi, Tetsuya Ishikawa, Tairo Oshima, Yoshitaka Bessho, Yasumasa Joti, Yoshinori Nishino

  Review of Scientific Instruments 91 (8) 083706 - 083706 0034-6748 2020/08/01 [Refereed][Not invited]
   

  We developed micro-liquid enclosure arrays (MLEAs) for holding solution samples in coherent diffractive imaging (CDI) using x-ray free-electron lasers (XFELs). Hundreds of fully isolated micro-liquid enclosures are arranged in a single MLEA chip for efficient measurement, where each enclosure is destroyed after exposure to a single XFEL pulse. A semi-automated MLEA assembling system was also developed to enclose solution samples into MLEAs efficiently at high precision. We performed XFEL-based CDI experiments using MLEAs and imaged in-solution structures of self-assembled gold nanoparticles. The sample hit rate can be optimized by adjusting solution concentration, and we achieved a single-particle hit rate of 31%, which is not far from the theoretical upper limit of 37% derived from the Poisson statistics. MELAs allow us to perform CDI measurement under controlled solution conditions and will help reveal the nanostructures and dynamics of particles in solution.
• Salt-triggered Active Plasmonic Systems Based on the Assembly/Disassembly of Gold Nanorods in a DNA Brush Layer on a Solid Substrate

  Satoshi Nakamura, Hideyuki Mitomo, Yusuke Yonamine, Kuniharu Ijiro

  CHEMISTRY LETTERS 49 (7) 749 - 752 0366-7022 2020/07 [Refereed]
   

  In this study, we demonstrate that the plasmonic properties of gold nanorods (GNRs) electrostatically adsorbed on a DNA brush substrate are reversibly controlled by changes in NaCl concentration. This plasmonic change results from GNR assembly/disassembly in a DNA brush layer. In addition, we show that this active plasmonic system exhibits intense and switchable chiroptical properties.
• Intrahelical Interactions in an alpha-Helical Coiled Coil Determine the Structural Stability of Tropomyosin

  Ken-Ichi Sano, Tsubasa Yuki, Yuta Nomata, Norihisa Nakayama, Ryo Iida, Hideyuki Mitomo, Kuniharu Ijiro, Yoshihito Osada

  BIOCHEMISTRY 59 (23) 2194 - 2202 0006-2960 2020/06 [Refereed]
   

  Tropomyosin (Tpm) is a two-stranded parallel alpha-helical coiled-coil protein, and studying its structure is crucial for understanding the nature of coiled coils. Previously, we found that the N-terminal half of the human skeletal muscle alpha-Tpm (alpha-Tpm 140) was less structurally stable in the presence of phosphate ions than the coiled-coil protein carrier (CCPC) 140 variant with 18 mutated residues, in which all amino acid residues located at the interface between the two alpha-helices were completely conserved. A classical hypothesis explains that interhelical interactions stabilize the coiled-coil structure. In this study, we tested the hypothesis that the structural stability of Tpm and its variant is governed by the binding of multivalent ions that form a bridge between charged side chains located at positions b, c, and f of the heptad repeat on a single alpha-helical chain. We found that the structural stability of alpha-Tpm 140 and CCPC 140 markedly increased upon addition of divalent cations and divalent anions, respectively. We also clarified that the structural stability of the alpha-Tpm 140/CCPC 140 heteromeric coiled-coil molecule was governed by the stability of a less stable alpha-helical chain. These results demonstrated that the entire structural stability of Tpm is determined by the stability of a single alpha-helix. Our findings provide new insights into the study of the structure of coiled-coil proteins.
• Strategy for Finely Aligned Gold Nanorod Arrays Using Polymer Brushes as a Template

  Satoshi Nakamura, Hideyuki Mitomo, Yu Sekizawa, Takeshi Higuchi, Yasutaka Matsuo, Hiroshi Jinnai, Kuniharu Ijiro

  LANGMUIR 36 (13) 3590 - 3599 0743-7463 2020/04 [Refereed]
   

  The development of a strategy for the assembly of nanoscale building blocks, in particular, anisotropic nanoparticles, into desired structures is important for the construction of functional materials and devices. However, control over the orientation of rodshaped nanoparticles on a substrate for integration into solid-state devices remains challenging. Here, we report a strategy for the fabrication of finely aligned gold nanorod (GNR) arrays using polymer (DNA) brushes as a nanoscale template. The gold nanorods modified with cationic surface ligands were electrostatically adsorbed onto the DNA brush substrates under various conditions. The orientational behavior of the GNRs was examined by spectral analyses and transmission electron microtomography (TEMT). As a result, we found several important factors, such as moderate interaction between GNRs and polymers and polymer densities on the substrate, related to the vertical alignment of GNRs on the substrates. We also developed a purification method to remove the undesired adsorption of GNRs onto the arrays. Finally, we have succeeded in the fabrication of extensive vertical GNR arrays of high quality via the easy bottom-up process.
• DNA Brush-Directed Vertical Alignment of Extensive Gold Nanorod Arrays with Controlled Density (vol 2, pg 2208, 2017)

  Satoshi Nakamura, Hideyuki Mitomo, Miho Aizawa, Takeharu Tani, Yasutaka Matsuo, Kenichi Niikura, Andrew Pike, Masayuki Naya, Atsushi Shishido, Kuniharu Ijiro

  ACS OMEGA 4 (15) 16701 - 16701 2470-1343 2019/10 [Refereed]
  
• Nanoscale uniformity in the active tuning of a plasmonic array by polymer gel volume change

  Satoru Hamajima, Hideyuki Mitomo, Takeharu Tani, Yasutaka Matsuo, Kenichi Niikura, Masayuki Naya, Kuniharu Ijiro

  NANOSCALE ADVANCES 1 (5) 1731 - 1739 2516-0230 2019/05 [Refereed]
   

  Active plasmonic tuning is an attractive but challenging research subject, leading to various promising applications. As one of the approaches, nanostructures are placed in or on soft matter, such as elastomers and gels, and their gap distances are tuned by the mechanical extension or volume change of the supporting matrices. As hydrogels possess various types of stimuli- responsiveness with large volume change and biocompatibility, they are good candidates as supporting materials for active nanostructure tuning. However, it remains unclear how accurately we can control their nanogap distance changes using polymer gels with a low deviation due to major difficulties in the precise observation of nanostructures on the gels. Here, we prepared gold arrays with sub- 100 nm dots on silicon substrates by electron beam lithography and transferred them onto the hydrogel surface. Then, their nanopattern was actively tuned by the changes in gel size in water and their structural changes were confirmed by optical microscopy, microspectroscopy, and atomic force microscopy ( AFM). Further, we successfully prepared ionic liquid ( IL) gels with various degrees of swelling via solvent exchange. Scanning electron microscopy ( SEM) observation of the IL gels provided clear pictures at nanoscale resolution. Finally, we calculated the plasmonic spectra using a finite difference time domain ( FDTD) simulation based on the SEM images and compared them with the measured spectra. The results in this study totally support the notion that active changes in plasmonic nanodot patterns via volume changes in the hydrogel are quite homogenous on a several nanometer scale, making them ideal for precise active surface plasmon tuning.
• Size-Defined Cracked Vesicle Formation via Self-Assembly of Gold Nanoparticles Covered with Carboxylic Acid-Terminated Surface Ligands

  Jinjian Wei, Hideyuki Mitomo, Takeharu Tani, Yasutaka Matsuo, Kenichi Niikura, Masayuki Naya, Kuniharu Ijiro

  Langmuir 34 (41) 12445 - 12451 0743-7463 2018/09 [Refereed][Not invited]
   

  The self-assembly of gold nanoparticles (GNPs) into a defined structure, particularly hollow capsule structures, provides great potential for applications in materials science and medicine. However, the complexity of the parameters for the preparation of those structures through self-assembly has limited access to critical mechanistic questions. With this in mind, we have studied GNP vesicle (GNV) formation through self-assembly by the surface modification of GNPs with low-molecular-weight ligands. Here, we successfully prepared GNVs composed of GNPs with a diameter of 30 nm by surface modification with carboxylic acid-terminated fluorinated oligo(ethylene glycol) ligands (CFLs). As the carboxylic acid has two states (protonated and deprotonated), the balance of the attraction and repulsion between GNPs covered with CFLs is tunable. Sodium carboxylate-terminated fluorinated oligo(ethylene glycol) ligands (SCFLs) provided smaller GNVs than did CFLs at 0.8 X 10(11) NPs/mL. Time-course study revealed that CFL-covered GNPs quickly form small aggregates and gradually grow to larger GNVs (ca. 200 nm), but no gradual growth was observed for SCFL-covered GNPs. This result indicated that the electrostatic repulsion inhibits fusion of the small GNVs. The size of the GNVs formed with the aid of CFLs was independent of the initial GNP concentration, but the extinction spectra were concentration-dependent. Electron microscopy imaging and simulations supported the defect formation in the assemblies. These results provided new insights into the vesicle formation mechanism.
• Two-Step Assembly of Thermoresponsive Gold Nanorods Coated with a Single Kind of Ligand

  Ryo Iida, Hideyuki Mitomo, Kenichi Niikura, Yasutaka Matsuo, Kuniharu Ijiro

  Small 14 (14) 1704230  1613-6829 2018/04/05 [Refereed][Not invited]
   

  Gold nanorods (GNRs) coated with a single kind of ligand show thermoreponsive two-step assembly to provide a hierarchical structure. The GNRs (33 nm in length × 14 nm in diameter) coated with a hexa(ethylene glycol) (HEG) derivative form side-by-side assemblies at 30 °C (TA1) as a steady state through dehydration. By further heating to over 40 °C (TA2), larger assemblies, which are composed of the side-by-side assembled units, are formed as hierarchical structures. The dehydration temperature of the HEG derivative varies depending on the free volume of the HEG unit, which corresponds to the curvature of the GNRs. Upon heating, dehydration first occurs from the ligands on the side portions with a lower curvature, and then from the ligands on the edge portions with a higher curvature. The different sized GNRs (33 × 8 and 54 × 15 nm) also show two-step assembly. Both the TA1 and TA2 are dependent on the diameter of the GNRs, but independent of their length. This result supports that the dehydration is dependent on the free volume, which corresponds to the curvature. Anisotropic assembly focusing on differences in curvature provides new guidelines for the fabrication of hierarchical structures.
• Shape-dependent adjuvanticity of nanoparticle-conjugated RNA adjuvants for intranasal inactivated influenza vaccines

  Taiyu Tazaki, Koshiro Tabata, Akira Ainai, Yuki Ohara, Shintaro Kobayashi, Takafumi Ninomiya, Yasuko Orba, Hideyuki Mitomo, Tetsuo Nakano, Hideki Hasegawa, Kuniharu Ijiro, Hirofumi Sawa, Tadaki Suzuki, Kenichi Niikura

  RSC Advances 8 (30) 16527 - 16536 2046-2069 2018 [Refereed][Not invited]
   

  Intranasal inactivated influenza vaccines can elicit mucosal immune responses that protect against virus infection. For the development of intranasal inactivated influenza vaccines, effective adjuvants inducing minimal adverse reactions are required. Generally, however, lower toxicity adjuvants have lower adjuvanticity. In this research, we fabricated nanoparticle-based adjuvants to enhance its adjuvanticity. Herein, we focused on low-molecular-weight polyinosinic-polycytidylic acid, referred to as uPIC(40:400), as a weak and less toxic RNA adjuvant. We conjugated uPIC(40:400) with different shaped gold nanoparticles (AuNPs) electrostatically. Conjugation with gold nanorods, but not spherical AuNPs, markedly enhanced the adjuvanticity of uPIC(40:400), leading to the suppression of viral infection in mice. Notably, conjugation with gold nanorods did not increase the inflammatory cytokine production in dendritic cells. These data indicated that gold nanorods can provide a good platform for enhancing the weak adjuvanticity of uPIC(40:400) while maintaining low inflammatory cytokine production toward the development of intranasal inactivated influenza vaccines.
• Preparation and Characterization of Double-Stranded DNA Brushes via Surface-Initiated Enzymatic Polymerization

  Hideyuki Mitomo, Satoshi Nakamura, Yasunobu Suzuki, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro

  JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 17 (12) 8995 - 9001 1533-4880 2017/12 [Refereed][Not invited]
   

  In this study, we have prepared double-stranded DNA brushes on glass or quartz substrates through the immobilization of biotinylated oligo-DNA, followed by hybridization and polymerization of the DNA by a surface-initiated enzymatic polymerization method. The density of the DNA brush was calculated based on UV spectra and agarose gel electrophoresis. Prepared DNA brushes showed a relatively high density of DNA chains (over 1500 chains/mu m(2)) independent of the length of the DNA. Atomic force microscopy of the 2D-patterned DNA brushes indicated dynamic changes in height under various salt concentrations. These results provided insight into the conformation of DNA brushes.
• Formation of Plasmonic Vesicles Through the Self-Assembly of Sugar-Terminated Fluorinated Oligo(ethylene glycol) Ligand-Tethered Gold Nanoparticles

  Jinjian Wei, Kenichi Niikura, Hideyuki Mitomo, Yasutaka Mastuo, Kuniharu Ijiro

  JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 17 (12) 9149 - 9156 1533-4880 2017/12 [Refereed][Not invited]
   

  We demonstrate that gold nanoparticles (GNPs) can spontaneously self-assemble to form hollow structures in the presence of sugar-terminated fluorinated-oligo(ethylene glycol) ligands. The size of the fabricated gold nanoparticle vesicles (GNVs) was dependent on the solvent properties, the number of glucose units at the terminal of the surface ligands, and the initial GNP concentration. Time-dependent studies showed that quick aggregation and subsequent slow fusion were involved in the GNV formation in solution.
• Metal nanoarchitecture fabrication using DNA as a biotemplate

  Kuniharu Ijiro, Hideyuki Mitomo

  POLYMER JOURNAL 49 (12) 815 - 824 0032-3896 2017/12 [Refereed][Not invited]
   

  Among the many important biopolymers, DNA has been a key component in material sciences and nanotechnology. We have focused on the fabrication of metal nanoarchitectures using DNA as a template due to its intrinsic properties and advantages, such as a well-ordered structure, rich chemical functionality and programmable base-pairing interactions, as well as the availability of multiple enzymes for DNA manipulation. In this review, various methods for the fabrication of DNA-templated metal nanoarchitecture are introduced. The methods include DNA-mediated metal nanoparticle formation, DNA-templated conductive nanowire fabrication by metal depositions, sequence-selective metal deposition onto DNA for elaborate nanowire fabrication and DNA brushes as templates for use on solid substrates. DNA sequence-selective binding of metal ions and metal complexes and subsequent reduction to metals are fundamental issues for the fabrication of metal nanoarchitectures. The resultant metal nanoparticles and their assemblies can be used as functional nanomaterials in applications such as catalysts, conducting nanowires, optical nanomaterials and especially in metamaterials. This biopolymer-templating method can be applied not only to metal deposition but also to the assembly of functional molecules.
• pH-Responsive Coassembly of Oligo(ethylene glycol)-Coated Gold Nanoparticles with External Anionic Polymers via Hydrogen Bonding

  Yu Torii, Naotoshi Sugimura, Hideyuki Mitomo, Kenichi Niikura, Kuniharu Ijiro

  LANGMUIR 33 (22) 5537 - 5544 0743-7463 2017/06 [Refereed][Not invited]
   

  Stimuli-responsive assembly of gold nanoparticles (AuNPs) with precise control of the plasmonic properties, assembly size, and stimuli responsivity has shown potential benefits with regard to biosensing devices and drug-delivery systems. Here we present a new pH-responsive coassembly system of oligo(ethylene glycol) (OEG)-coated AuNPs with anionic polymers as an external mediator via hydrogen bonding in water. Hydrogen-bond-driven coassemblies of OEG-AuNPs with poly(acrylic acid) (PAA) were confirmed by the monitoring of plasmonic peaks and hydrodynamic diameters. In this system, the protonation of anionic polymers on change in pH triggered the formation of hydrogen bond between the OEG-AuNPs and polymers, providing sensitive pH responsivity. The plasmonic properties and assembly size are affected by both the ratio of PAA to AuNPs and the molecular weight of PAAs. In addition, the attachment of hydrophobic groups to the surface ligand or anionic polymer changed the responsive pH range. These results demonstrated that the coassembly with an external mediator via hydrogen bonding provides a stimuli-responsive assembly system with tunable plasmonic properties, assembly size, and stimuli responsivity.
• DNA Brush-Directed Vertical Alignment of Extensive Gold Nanorod Arrays with Controlled Density

  Satoshi Nakamura, Hideyuki Mitomo, Miho Aizawa, Takeharu Tani, Yasutaka Matsuo, Kenichi Niikura, Andrew Pike, Masayuki Naya, Atsushi Shishido, Kuniharu Ijiro

  ACS Omega 2 (5) 2208 - 2213 2470-1343 2017/05/31 [Refereed][Not invited]
   

  Control over the orientation of metal nanorods is important for both fundamental and applied research. We show that gold nanorods (GNRs) can be aligned in a single direction by adsorbing positively charged GNRs onto a double-strand DNA-grafted substrate through electrostatic interaction. The ordered structure can be optimized by controlling the density of the positive charges on the surface of the GNRs. We found, in agreement with the results of theoretical simulation, that the resultant structure exhibits plasmonic properties that are dependent on the GNR orientation relative to the direction of an oscillating electric field. Our approach provides new insights into the polymer-assisted self-assembly of rod-shaped nanoparticles utilizing electrostatic interactions.
• Reverse Size Dependences of the Cellular Uptake of Triangular and Spherical Gold Nanoparticles

  Katsuyuki Nambara, Kenichi Niikura, Hideyuki Mitomo, Takafumi Ninomiya, Chie Takeuchi, Jinjian Wei, Yasutaka Matsuo, Kuniharu Ijiro

  LANGMUIR 32 (47) 12559 - 12567 0743-7463 2016/11 [Refereed][Not invited]
   

  Gold nanoparticles (GNPs) show promise as both drug and imaging carriers with applications in both diagnosis and therapy. For the safe and effective use of such gold nanomaterials in the biomedical field, it is crucial to understand how the size and shape of the nanomaterials affect their biological features, such as in vitro cellular uptake speed and accumulation as well as cytotoxicity. Herein, we focus on triangular gold nanoparticles (TNPs) of four different sizes (side length 46, 55, 72, and 94 nm; thickness 30 nm) and compare the cellular internalization efficiency with those of spherical nanoparticles (SNPs) of various diameters (22, 39, and 66 nm). Both surfaces were coated with anionic thiol ligands. Inductively coupled plasma emission spectrometry (ICP-ES) data demonstrated that TNPs with longer sides showed higher levels of uptake into RAW264.7 and HeLa cells. On the other hand, in the case of SNPs, those with smaller diameters showed higher levels of uptake in both cells. Our results support the notion of a reverse size dependence of TNPs and SNPs in terms of cellular uptake. For HeLa cells, in particular, 20-fold more efficient internalization was observed for TNPs with longer sides (72 nm side length) compared to SNPs (66 nm) with a similar surface area. These results highlight the importance of the shape of nanomaterials on their interactions with cells and provide a useful guideline for the use of TNPs.
• Thermoresponsive Assembly of Gold Nanoparticles Coated with Oligo(Ethylene Glycol) Ligands with an Alkyl Head

  Ryo Iida, Hideyuki Mitomo, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro

  JOURNAL OF PHYSICAL CHEMISTRY C 120 (29) 15846 - 15854 1932-7447 2016/07 [Refereed][Not invited]
   

  This paper presents the thermoresponsive assembly behaviors of gold nanoparticles (AuNPs; 3, 5, and 10 nm in diameter) that are coated with a self-assembled monolayer of oligo(ethylene glycol) (OEG) ligands terminated with alkyl heads. AuNPs (5 nm in diameter) coated with OEG ligands without an alkyl head did not assemble within a temperature range from 20 to 70 degrees C. However, AuNPs coated with ethyl, iso-propyl, and propyl-headed OEG AuNPs afforded assembly at temperatures of 56, 33, and 19 degrees C, respectively, indicating that the assembly temperature can be tuned over a wide range by slight changes in the hydrophobicity of the alkyl head. Almost no hysteresis during the heating/cooling cycles was observed for the assembly/disassembly process. The diameter of the AuNPs also affected the assembly temperature, with increases in the diameter of the AuNP affording a lower assembly temperature. The ligand with the shorter alkyl tail length provided the lower assembly temperature of AuNPs than the ligand with longer tail.
• Yolk/Shell Assembly of Gold Nanoparticles by Size Segregation in Solution

  Jinjian Wei, Kenichi Niikura, Takeshi Higuchi, Takashi Kimura, Hideyuki Mitomo, Hiroshi Jinnai, Yasumasa Joti, Yoshitaka Bessho, Yoshinori Nishino, Yasutaka Matsuo, Kuniharu Ijiro

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 138 (10) 3274 - 3277 0002-7863 2016/03 [Refereed][Not invited]
   

  We demonstrate that binary mixtures of small and large gold nanoparticles (GNPs) (5/15, 5/30, 10/30, and 15/30 nm in diameter) in the presence of a glucose-terminated fluorinated oligo(ethylene glycol) ligand can spontaneously form size-segregated assemblies. The outermost layer of the assembly is composed of a single layer of small-sized GNPs, while the larger-sized GNPs are located in the interior, forming what is referred to as a yolk/shell assembly. Time course study reveals that small and large GNPs aggregate together, and these kinetically trapped aggregations were transformed into a size-segregated structure by repeating fusions. A yolk/shell structure was directly visualized in solution by X-ray laser diffraction imaging, indicating that the structure was truly formed in solution, but not through a drying process.
• Active Gap SERS for the Sensitive Detection of Biomacromolecules with Plasmonic Nanostructures on Hydrogels

  Hideyuki Mitomo, Kenta Horie, Yasutaka Matsuo, Kenichi Niikura, Takeharu Tani, Masayuki Naya, Kuniharu Ijiro

  ADVANCED OPTICAL MATERIALS 4 (2) 259 - 263 2195-1071 2016/02 [Refereed][Not invited]
  
• Fabrication of a Novel Cell Culture System Using DNA-Grafted Substrates and DNase

  Hideyuki Mitomo, Asumi Eguchi, Yasunobu Suzuki, Yasutaka Matsuo, Kenichi Niikura, Kohji Nakazawa, Kuniharu Ijiro

  JOURNAL OF BIOMEDICAL NANOTECHNOLOGY 12 (2) 286 - 295 1550-7033 2016/02 [Refereed][Not invited]
   

  In conventional cell culture systems, trypsin is generally used for cell harvesting. However, trypsin damages the cells due to the nonselective degradation of proteins on the cell surface. This is a critical issue for cell culture systems. Therefore, an alternative cell culture system with the lowest possible impact on cells is desired. In this paper, we have focused on DNA as a sacrificial layer and DNase as an alternate enzyme instead of trypsin. DNase ought not to result in damage to or stress on cells as it only hydrolyzes DNAs while the plasma membrane and extracellular matrices are basically composed of lipids, proteins, and glycosides. Therefore, we fabricated DNA-grafted substrates as cell culture dishes and evaluated this novel cell culture system. As a result, we were able to culture several types of mammalian cells on the DNA-grafted substrates, with the cells harvested using DNase with only little damage to the cells. This cell culture system could provide a breakthrough in cell culturing technology.
• Self-Organization beyond the Molecule: Control of Nanoparticle Assemblies by Their Surface Properties and Their Functional Applications

  Hideyuki Mitomo, Kenichi Niikura, Kuniharu Ijiro

  KOBUNSHI RONBUNSHU 73 (2) 147 - 156 0386-2186 2016 [Refereed][Not invited]
   

  In recent years, self-assembly beyond the molecule, which combines biological chemistry, materials science and nano- or micro-meter scale technology, has attracted much attention. Fundamental research on the self-assembly of non-molecular systems such as metal nanoparticles, which are regarded as "artificial molecules'', can enhance our understanding of the concept of self-assembly. Herein, we propose a robust strategy for the dimension-controllable fabrication of nano-assemblies of nanoparticles through tuning inter-particle interactions using suitable surface ligands. The formation of hydrogels consisting of a fibrous assembly of quantum dots (QDs), multi-layered gold nanoparticles (AuNPs), and AuNP vesicles as well as their prospective applications are investigated. The development of AuNP vesicles with hollow structures and special optical properties motivated by biomimetics has been extensively explored in medicinal chemistry for potential application to drug delivery systems (DDSs) and as a platform for surface-enhanced Raman scattering as an analytical tool. Novel self-assembly strategies using Janus-like nanoparticles are also discussed.
• DNA-modulated photo-transformation of AgCl to silver nanoparticles: visiting the formation mechanism

  Guoqing Wang, Hideyuki Mitomo, Yasutaka Matsuo, Kenichi Niikura, Mizuo Maeda, Kuniharu Ijiro

  JOURNAL OF COLLOID AND INTERFACE SCIENCE 452 224 - 234 0021-9797 2015/08 [Refereed][Not invited]
   

  Solution-phase synthesis and post-synthetic bio-modification have continued to play a dominant role in preparation of nanostructured biomaterials. Heterogeneous nucleation and growth that occur much more often in nature, however, remain rarely explored in nano-biomaterials research. We have newly developed a DNA-modulated photoconversion approach to uniform silver nanoparticles that afford DNA-directed recognition and multi-mode imaging. The present study was aimed at understanding the rapid heterogeneous nucleation and growth of AgNPs at the solid-liquid interface with the aid of DNA. Dynamic changes in absorbance, size and morphology of silver nanostructures were monitored and analyzed to clarify the growth kinetics, which indicated a synthetic route involving synchronous growth of silver nanostructures and the fragmentation and consumption of AgCl. Various stabilizers, including polymer and amino acids, were assessed and compared with respect to the efficacy in photoconversion of AgCl. DNA was found to offer the best monodispersity and the smallest diameter for the resultant AgNPs, due to its strong interactions to silver species as well as excellent charge dispersion ability. By controlling the physicochemical property of DNA through choice of pH and ionic strength, we have demonstrated tunable structure and composition of the nanoparticles. (C) 2015 Elsevier Inc. All rights reserved.
• Synthesis of Janus-Like Gold Nanoparticles with Hydrophilic/Hydrophobic Faces by Surface Ligand Exchange and Their Self-Assemblies in Water

  Ryo Iida, Hitoshi Kawamura, Kenichi Niikura, Takashi Kimura, Shota Sekiguchi, Yasumasa Joti, Yoshitaka Bessho, Hideyuki Mitomo, Yoshinori Nishino, Kuniharu Ijiro

  LANGMUIR 31 (14) 4054 - 4062 0743-7463 2015/04 [Refereed][Not invited]
   

  This study aims at the synthesis of Janus gold nanoparticles (Janus GNPs) with hydrophilic/hydrophobic faces by a simple ligand exchange reaction in an homogeneous system and at the elucidation of the self-assembled structures of the Janus GNPs in water. As hydrophilic surface ligands, we synthesized hexaethylene glycol (E6)-terminated thiolate ligands with C3, C7, or C11 alkyl chains, referred to as E6C3, E6C7, and E6C11, respectively. As a hydrophobic ligand, a butyl-headed thiolate ligand C4-E6C11, in which a C4 alkyl was introduced on the E6C11 terminus, was synthesized. The degree of segregation between the two ligands on the GNPs (5 nm in diameter) was examined by matrix-assisted laser desorption/ionization time-of fright mass spectrometry (MALDI-TOF MS) analysis. We found that the choice of immobilization methods, one-step or two-step addition of the two ligands to the GNP solution, crucially affects the degree of segregation. The two-step addition of a hydrophilic ligand (E6C3) followed by a hydrophobic ligand (C4-E6C11) produced a large degree of segregation on the GNPs, providing Janus-like GNPs. When dispersed in water, these Janus-like GNPs formed assemblies of similar to 160 nm in diameter, whereas Domain GNPs, in which the two ligands formed partial domains on the surface, were precipitated even when the molar ratio of the hydrophilic ligand and the hydrophobic ligand on the surface of the NPs was almost 1:1. The assembled structure of the Janus-like GNPs in water was directly observed by pulsed coherent X-ray solution scattering using an X-ray free-electron laser, revealing irregular spherical structures with uneven surfaces.
• Encapsulation of a gold nanoparticle in a DNA origami container

  Akinori Kuzuya, Masafumi Kaino, Mirai Hashizume, Kazuki Matsumoto, Takeaki Uehara, Yasutaka Matsuo, Hideyuki Mitomo, Kenichi Niikura, Kuniharu Ijiro, Yuichi Ohya

  POLYMER JOURNAL 47 (2) 177 - 182 0032-3896 2015/02 [Refereed][Not invited]
   

  A box-shaped' three-dimensional (3D) DNA origami of similar to 40-nm dimensions was selectively formed by closing a symmetric open motif with three orthogonal faces. This 3D DNA origami was used as an intelligent nano-container to encapsulate exactly one 10-nm gold nanoparticle (AuNP). AuNPs were functionalized with thiol-modified DNA strands and attached to one of the faces of the open motif, which was designed to be an interior surface of the box and decorated with three complementary strands. The open motif was then closed into the box shape as triggered by the addition of DNA strands joining the remaining edges. An examination of the suitable folding path of an M13 scaffold using fluorescently labeled staple strands revealed that the flexibility at the hinge was essential for the efficient closing of the DNA origami container. Atomic force microscope and transmission electron microscope imaging of agarose-gel-purified complexes clearly showed the successful encapsulation of one AuNP inside the shell.
• Enzymatic Synthesis of a DNA Triblock Copolymer that is Composed of Natural and Unnatural Nucleotides

  Hideyuki Mitomo, Yukie Watanabe, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro

  CHEMISTRY-AN ASIAN JOURNAL 10 (2) 455 - 460 1861-4728 2015/02 [Refereed][Not invited]
   

  DNA molecules have come under the spotlight as potential templates for the fabrication of nanoscale products, such as molecular-scale electronic or photonic devices. Herein, we report an enhanced approach for the synthesis of oligoblock copolymer-type DNA by using the Klenow fragment exonuclease minus of E. coli DNA polymerase I (KF-) in a multi-step reaction with natural and unnatural nucleotides. First, we confirmed the applicability of unnatural nucleotides with 7-deaza-nucleosides-which was expected because they were non-metalized nucleotides-on the unique polymerization process known as the "strand-slippage model". Because the length of the DNA sequence could be controlled by tuning the reaction time, analogous to a living polymerization reaction on this process, stepwise polymerization provided DNA block copolymers with natural and unnatural bases. AFM images showed that this DNA block copolymer could be metalized sequence-selectively. This approach could expand the utility of DNA as a template.
• Amphiphilic Gold Nanoparticles Displaying Flexible Bifurcated Ligands as a Carrier for siRNA Delivery into the Cell Cytosol

  Kenichi Niikura, Kenya Kobayashi, Chie Takeuchi, Naoki Fujitani, Shuko Takahara, Takafumi Ninomiya, Kyoji Hagiwara, Hideyuki Mitomo, Yoshihiro Ito, Yoshihito Osada, Kuniharu Ijiro

  ACS APPLIED MATERIALS & INTERFACES 6 (24) 22146 - 22154 1944-8244 2014/12 [Refereed][Not invited]
   

  The nanoparticle-based delivery of siRNA with a noncationic outermost surface at a low particle concentration is greatly desired. We newly synthesized a bifurcated ligand (BL) possessing hydrophobic and hydrophilic arms as a surface ligand for gold nanoparticles (AuNPs) to allow siRNA delivery. The concept underlying the design of this ligand is that amphiphilic property should allow AuNPs to permeate the cell cytosol thorough the endosomal membrane. BLs and quaternary cationic ligands were codisplayed on 40 nm AuNPs, which were subsequently coated with siRNA via electrostatic interaction. The number of siRNAs immobilized on a single nanoparticle was 26, and the conjugate showed a negative zeta potential due to siRNAs on the outermost surface of the AuNPs. Apparent gene silencing of luciferase expression in HeLa cells was achieved at an AuNP concentration as low as 60 pM. Almost no gene silencing was observed for AuNPs not displaying BLs. To reveal the effect of the BL, we compared the number of AuNPs internalized into HeLa cells and the localization in the cytosol between AuNPs displaying and those not displaying BLs. These analyses indicated that the role of BLs is not only the simple promotion of cellular uptake but also involves the enhancement of AuNPs permeation into the cytosol from the endosomes, leading to effective gene silencing.
• Enhanced cellular uptake of amphiphilic gold nanoparticles with ester functionality

  Kenya Kobayashi, Kenichi Niikura, Chie Takeuchi, Shota Sekiguchi, Takafumi Ninomiya, Kyoji Hagiwara, Hideyuki Mitomo, Yoshihiro Ito, Yoshihito Osada, Kuniharu Ijiro

  CHEMICAL COMMUNICATIONS 50 (10) 1265 - 1267 1359-7345 2014 [Refereed][Not invited]
   

  Gold nanoparticles (AuNPs) coated with ester-headed or ether-headed PEG ligands were synthesized. Ester-headed AuNPs, but not ether-headed, were transferred from the organic phase (CH2Cl2) to the alkali aqueous phase, indicating that the hydrolysis of the ester moiety triggered the phase transfer of the AuNPs. We found that AuNPs with ester-headed ligands (ester-AuNPs) were internalized into HeLa cells at a greater level than were ether-headed AuNPs.
• DNA-templated plasmonic Ag/AgCl nanostructures for molecular selective photocatalysis and photocatalytic inactivation of cancer cells

  Guoqing Wang, Hideyuki Mitomo, Yasutaka Matsuo, Naonobu Shimamoto, Kenichi Niikura, Kuniharu Ijiro

  Journal of Materials Chemistry B 1 (43) 5899 - 5907 2050-7518 2013/12/21 [Refereed][Not invited]
   

  Silver halide (AgX, X = Cl, Br, I)-based materials represent an emerging class of heterogeneous photocatalysts. Despite progress in the synthesis of carrier-separated AgX-based photocatalysts, a number of issues remain unaddressed, including complicated synthesis, unfavorably large size and therefore poor photocatalytic performance of the resultant structures. Here we show the one-step DNA-programmable synthesis of Ag/AgCl nanostructures that takes only approximately 1 min for photocatalytic application. The optimal DNA-encapsulated structures show DNA sequence-specific sizes down to less than 40 nm with a Ag/AgCl composition ratio of 2:1, affording a vastly increased surface area and higher photocatalytic activity than any Ag/AgX nanostructures reported previously by over two orders of magnitude. From a physical standpoint, importantly, the plasmonic nanostructured silver in Ag/AgCl accelerates the photocatalytic reaction in terms of fast electron injection to AgCl, leading to enhanced hole-electron separation and high-performance photocatalysis under visible light. To test the effect of DNA encapsulation on the Ag/AgCl nanostructures, both positively and negatively charged organic compounds serve as the model pollutants to assess their photocatalytic selectivity. Our results show that the photodecomposition of the positively charged compounds obeys a first-order rate law, whereas the negatively charged compound is decomposed with zero-order kinetics. This comparison offers a mechanistic insight into reaction kinetics on the DNA-encapsulated photocatalyst. We further find that the DNA-encapsulated Ag/AgCl photocatalysts are robust and can be recycled. To extend the applicability of the Ag/AgCl nanostructures, their use in the efficient photocatalytic inactivation of cancer cells is also demonstrated for the first time, opening up a new avenue to daylight-based theranostics. © 2013 The Royal Society of Chemistry.
• 337-340 Preparation of triblock dna as a template for fabrication of nano-gap structures using sequence-selective metallization

  Hideyuki Mitomo, Yukie Watanabe, Yasutaka Matsuo, Kenichi Nidcura, Kuniharu Liro

  Kobunshi Ronbunshu 70 (7) 337 - 340 0386-2186 2013/07 [Refereed][Not invited]
   

  Top-down processes, such as photolithography, have been approaching a limit with regard to the fabrication of fine structures. For the preparation of molecular-scale fine structures, it is important that conventional self-assembly methods should be adapted to a "programmable self-assembly" as a next-generation bottom-up system. We aim to fabricate nano-gap electrodes by sequence-selective metallization of template DNA. We have already reported the fabrication of sequence-selective platinum nano-wires using poly(guanine) and poly(adenine-thymine) diblock DNA, which is enzymatically polymerized as a template. That method, however, cannot be extended to the preparation of oligoblock DNA. In this study, we prepared triblock DNA sequences using guanine as a platinum-binding natural nucleotide and 7-deaza-guanine as a platinum-nonbinding unnatural nucleotide for the construction of platinum nano-wires with nano-gap structures. ©2013, The Society of Polymer Science,.
• Sub-100 nm Gold Nanoparticle Vesicles as a Drug Delivery Carrier enabling Rapid Drug Release upon Light Irradiation

  Kenichi Niikura, Naoki Iyo, Yasutaka Matsuo, Hideyuki Mitomo, Kuniharu Ijiro

  ACS APPLIED MATERIALS & INTERFACES 5 (9) 3900 - 3907 1944-8244 2013/05 [Refereed][Not invited]
   

  Previously, we reported gold nanoparticles coated with semi-fluorinated ligands self-assembled into gold nanoparticle vesicles (AuNVs) with a sub-100 nm diameter in tetrahydrofuran (THF).(1) Although this size is potentially useful for in vivo use, the biomedical applications of AuNVs were limited, as the vesicular structure collapsed in water. In this paper, we demonstrate that the AuNVs can be dispersed in water by cross-linking each gold nanoparticle with thiol-terminated PEG so that the cross-linked vesicles can work as a drug delivery carrier enabling light-triggered release. Rhodamine dyes or anticancer drugs were encapsulated within the cross-linked vesicles by heating to 62.5 degrees C. At this temperature, the gaps between nanoparticles open, as confirmed by a blue shift in the plasmon peak and the more efficient encapsulation than that observed at room temperature. The cross-linked AuNVs released encapsulated drugs upon short-term laser irradiation (5 min, 532 nm) by again opening the nanogaps between each nanoparticle in the vesicle. On the contrary, when heating the solution to 70 degrees C, the release speed of encapsulated dyes was much lower (more than 2 h) than that triggered by laser irradiation, indicating that cross-linked AuNVs are highly responsive to light. The vesicles were efficiently internalized into cells compared to discrete gold nanoparticles and released anticancer drugs upon laser irradiation in cells. These results indicate that cross-linked AuNVs, sub-100 nm in size, could be a new type of light-responsive drug delivery carrier applicable to the biomedical field.
• Nanopattern Fabrication of Gold on Hydrogels and Application to Tunable Photonic Crystal

  Naonobu Shimamoto, Yoshito Tanaka, Hideyuki Mitomo, Ryuzo Kawamura, Kuniharu Ijiro, Keiji Sasaki, Yoshihito Osada

  ADVANCED MATERIALS 24 (38) 5243 - 5248 0935-9648 2012/10 [Refereed][Not invited]
  
• Hydrophilic double-network polymers that sustain high mechanical modulus under 80% humidity

  Taiki Tominaga, Ken-Ichi Sano, Jun Kikuchi, Hideyuki Mitomo, Kuniharu Ijiro, Yoshihito Osada

  ACS Macro Letters 1 (3) 432 - 436 2161-1653 2012 [Refereed][Not invited]
   

  The effects of water on the mechanical properties of synthetic hydrophilic polymers with doublenetwork (DN) structures were studied under different relative humidities (RH). It was found that they could sustain nearly the same high Young's modulus as dry DN polymers in the RH range 10-80% (water content 3-17 wt %), that is, more than 102 MPa. However, when the RH exceeds 80%, DN polymers abruptly absorb large amounts of water (water content 90 wt %) and transform to a highly water-swollen "gel state" with a decrease in the Young's modulus of 3 orders of magnitude. Spectroscopic analyses revealed that water molecules below RH 80% are strongly bound to hydrophilic moieties with highly restricted mobility water under such states improves rather than reduces mechanical properties by behaving as a plasticizer. DN polymers capable of sustaining high mechanical properties, even under RH 80%, have potential uses as hydrophilic materials. © 2012 American Chemical Society.
• Phospholipid Complexation of General Anesthetics in Fluid Bilayers

  Serhan Turkyilmaz, Hideyuki Mitomo, Wen-Hua Chen, Steven L. Regen

  LANGMUIR 26 (8) 5309 - 5311 0743-7463 2010/04 [Refereed][Not invited]
   

  A nearest-neighbor recogntion analysis has been performed in cholesterol-rich and cholesterol-poor liposomes derived from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the presence of varying concentrations of chloroform. This analysis has yielded a funamentally new, molecular-level view of the interaction of general anesthetics with lipid bilayers, which may be relevant to their biological action; that is, DPPC Forms 1:1 complexes with CHCl(3) in both membranes in the fluid bilayer state.
• Oxysterol-Induced Rearrangement of the Liquid-Ordered Phase: A Possible Link to Alzheimer's Disease?

  Hideyuki Mitomo, Wen-Hua Chen, Steven L. Regen

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 (34) 12354 - 12357 0002-7863 2009/09 [Refereed][Not invited]
   

  Nearest-neighbor recognition measurements have been made for an exchangeable phospholipid (A) interacting with an exchangeable form of cholesterol (B) in host membranes derived from 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine and varying concentrations of cholesterol, 7 beta-hydroxycholesterol (7 beta-OH), and 25-hydroxycholesterol (25-OH). Whereas partial replacement of cholesterol with 7 beta-OH strengthens the association between A and B, a similar substitution with 25-OH weakens this association. A model that accounts for this dichotomy, and the possible relevance of these findings to the cytotoxicity of 7 beta-OH and to Alzheimer's disease are briefly discussed.
• Reduced Sterol-Phospholipid Recognition in Curved Fluid Bilayers

  Hideyuki Mitomo, Wen-Hua Chen, Steven L. Regen

  LANGMUIR 25 (8) 4328 - 4330 0743-7463 2009/04 [Refereed][Not invited]
   

  Nearest-neighbor recognition experiments have been carried out in fluid liposomal membranes made from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol using exchangeable dimers derived from 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine and cholesterol. In cholesterol-rich bilayers, the association between these two exchangeable lipids was reduced as the curvature of the membrane increases; that is, when the diameter of the liposomes was below ca. 200 nm. In sharp contrast, the mixing of these exchangeable lipids was close to random in the cholesterol-poor membranes, regardless of their curvature. The biological implications of these findings are briefly discussed.
• Loosening and Reorganization of Fluid Phospholipid Bilayers by Chloroform

  Serhan Turkyilmaz, Wen-Hua Chen, Hideyuki Mitomo, Steven L. Regen

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 (14) 5068 - + 0002-7863 2009/04 [Refereed][Not invited]
   

  The mixing behavior of an exchangeable phospholipid (A) with an exchangeable sterol (B) in host. bilayers made from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) containing varying concentrations of cholesterol has been examined via the nearest-neighbor recognition method. At low sterol concentrations (i.e., 2.5 mol %) the mixing between A and B is close to ideal. Incremental increases in the sterol concentration to 40 mol % led to net increases in the affinity between A and B. Similar mixing experiments that were carried out in the presence of chloroform showed a leveling effect, where moderate sterol-phospholipid affinity was observed in all cases. These results, together with the fact that the number of chloroform molecules that are absorbed per phospholipid is essentially constant and independent of the sterol content, support a model in which chloroform favors solvation of the phospholipids and a common membrane state is produced. Fluorescence measurements and Raman spectra have also shown that chloroform significantly loosens both cholesterol-poor and cholesterol-rich membranes made from DPPC. In a broader context, these results suggest a fundamentally new mechanim of anesthesia, where the anesthetic, by solvating the lipid components, profoundly changes the lateral organization of the lipid framework.
• IgG binding kinetics to oligo B protein A domains on lipid layers quartz-crystal immobilized on a 27 MHz microbalance

  Hideyuki Mitomo, Hideki Shigematsu, Eiry Kobatake, Hiroyuki Furusawa, Yoshio Okahata

  JOURNAL OF MOLECULAR RECOGNITION 20 (2) 83 - 89 0952-3499 2007/03 [Refereed][Not invited]
   

  Although molecular recognitions between membrane receptors and their soluble ligands have been analyzed using their soluble proteins in bulk solutions, molecular recognitions of membrane receptors should be studied on lipid membranes considering their orientation and dynamics on membrane surfaces. We employed Staphylococcal Protein A (SpA) oligo B domains with long trialkyl-tags from E. coli (LppBx, x = 1, 2, and 5) and immobilized LppBx on lipid layers using hydrophobic interactions from the trialkyl-tag, while maintaining the orientation of B domain-chains on a 27 MHz quartz-crystal microbalance (QCM; AT-cut shear mode). The binding of IgG Fc regions to LppBx on lipid layers was detected by frequency decreases (mass increases) on the QCM. The maximum amount bound (Delta m(max)), association constants (K-a), association and dissociation rate constants (k(1) and k(-1), respectively) were obtained. Binding kinetics of IgG to LppB2 and LppB5 were quite similar, showing a simple 1:1 binding of the IgG Fc region to the B domain, when the surface coverage of LppB2 and LppB5 on the lipid surface is low (1.4%). When LppB5 was immobilized at the high surface coverage of 3.5%, the complex bindings of IgG such as one IgG bound to one or two LppB5 on the membrane could be observed. IgG-LppB1 binding was largely restricted because of steric hindrance on lipid surfaces. This gives a suggestion why Protein A has five IgG binding domains. Copyright (c) 2007 John Wiley & Sons, Ltd.
• Compositional and structural engineering of DNA multilayer films

  APR Johnston, H Mitomo, ES Read, F Caruso

  LANGMUIR 22 (7) 3251 - 3258 0743-7463 2006/03 [Refereed][Not invited]
   

  We report the layer-by-layer (LbL) preparation of multilayered thin films that consist solely of DNA. The properties of the films were varied by assembling the layers from different oligonucleotide building blocks. which are composed of repeating homopolymeric units of nucleotides [adenosine (A), cytosine (C). guanine (G). and thymidine (T)] or "random" sequences. Films assembled from oligonucleotides with a single complementary unit did not show continual layer buildup. To form a repeating multilayer system, it was necessary for single-stranded DNA to be available for subsequent layers to hybridize. By using oligonucleotides with multiple nucleotide units, multilayer films were Successfully assembled. We demonstrate that the thickness and swellability of the films can be controlled by the extent of hydrogen bonding (the G/C content of the oligonucleotide) and orientation of the oligomers. We have examined the stability and swellability of the films in solutions of varying salt concentration as well as in a denaturing urea solution. Stable, hollow DNA capsules were also formed by preparing the films on sacrificial colloidal templates. followed by removal of the core. The assembly of propagating structures through DNA hybridization paves the way for the engineering of DNA films with tailored composition, structure, and permeability, making them likely to find application in drug/gene delivery and biomolecular sensing.
• Reconstitution of supported lipid bilayer on a quartz-crystal microbalance

  Hideyuki Mitomo, Yukari Ishizu, Hiroyuki Furusawa, Yoshio Okahata

  Polymer Preprints, Japan 55 (2) 5302 - 5303 2006 

  Although molecular recognitions on membrane receptors are important, they have not fully studied because of difficulties of separation and immobilization of membrane proteins. In this study, we prepared a supported lipid bilayer membrane containing membrane receptors on a 27 MHz quartz crystal microbalance (QCM) surface. Membrane proteins solubilized with surfactants from cell membrane were immobilized by two methods. The first method is to prepare supported layers by using a biotinylated lipid on an avidin-immobilized QCM and then to remove surfactants from the mixed membrane of protein-lipid surfactant. The second method is to immobilize a biotinylated membrane protein on an avidin-immobilized QCM and then to cover the embedded proteins with lipid bilayers.
• Transport of SN-38 by the Wild Type of Human ABC Transporter ABCG2 and Its Inhibition by Quercetin, a Natural Flavonoid

  Megumi Yoshikawa, Yoji Ikegami, Kazumi Sano, Hisahiro Yoshida, Hideyuki Mitomo, Seigo Sawada, Toshihisa Ishikawa

  Journal of Experimental Therapeutics and Oncology 4 (1) 25 - 35 1359-4117 2004 [Refereed][Not invited]
   

  Irinotecan (CPT-11) is a widely-used potent anticancer drug that inhibits mammalian DNA topoisomerase I, however overexpression of the ATP-binding cassette transporter ABCG2 can confer cancer cells resistance to SN-38, the active form of CPT-11. In the present study, we have examined the contribution of three variant forms of ABCG2 to SN-38 resistance. Exogenous expression of the Arg482 (wild type), Gly482, and Thr482 variants of ABCG2 conferred HEK293 cells resistance to SN-38 by 15.0-, 5.0-, and 5.3-fold, respectively. In plasma membrane vesicles prepared from the ABCG2 variant cDNA-transfected HEK293 cells, [Arg482]ABCG2 transported SN-38 and its glucuronide conjugate in an ATP-dependent manner however, only minimal transport activities were observed with the other variants (Gly482 and Thr482). In addition, we have screened natural flavonoids to find potent inhibitors of [Arg482]ABCG2. Quercetin was found to be the strongest inhibitor (Ki = 0.28 μM) among natural flavonoids tested in the plasma membrane system in this study. When [Arg482]ABCG2-transfected HEK293 cells were incubated with SN-38 in the presence of 20 μM quercetin, cellular resistance to SN-38 was partly reversed. In this context, certain flavonoid derivatives are considered to be good candidates for development of ABCG2 inhibitors.
• A functional study on polymorphism of the ATP-binding cassette transporter ABCG2: critical role of arginine-482 in methotrexate transport

  H Mitomo, R Kato, A Ito, S Kasamatsu, Y Ikegami, Kii, I, A Kudo, E Kobatake, Y Sumino, T Ishikawa

  BIOCHEMICAL JOURNAL 373 (3) 767 - 774 0264-6021 2003/08 [Refereed][Not invited]
   

  Overexpression of the ATP-binding cassette transporter ABCG2 reportedly causes multidrug resistance, whereas altered drug-resistance profiles and substrate specificity are implicated for certain variant forms of ABCG2. At least three variant forms of ABCG2 have been hitherto documented on the basis of their amino acid moieties (i.e., arginine, glycine and threonine) at position 482. In the present study we have generated those ABCG2 variants by site-directed mutagenesis and expressed them in HEK-293 cells. Exogenous expression of the Arg(482), Gly(482) and Thr(482) variant forms of ABCG2 conferred HEK-293 cell resistance toward mitoxantrone 15-, 47- and 54-fold, respectively, as compared with mock-transfected HEK-293 cells. The transport activity of those variants was examined by using plasma-membrane vesicles prepared from ABCG2-overexpressing HEK293 cells. [Arg(482)]ABCG2 transports [H-3]methotrexate in an ATP-dependent manner; however, no transport activity was observed with the other variants (Gly(482) and Thr(482)). Transport of methotrexate by [Arg(482).]ABCG2 was significantly inhibited by mitoxantrone, doxorubicin and rhodamine 123, but not by S-octylglutathione. Furthermore, ABCG2 was found to exist in the plasma membrane as a homodimer bound via cysteinyl disulphide bond(s). Treatment with mercaptoethanol decreased its apparent molecular mass from 140 to 70 kDa. Nevertheless, ATP-dependent transport of methotrexate by [Arg(482)]ABCG2 was little affected by such mercaptoethanol treatment. It is concluded that Arg 412 is a critical amino acid moiety in the substrate specificity and transport of ABCG2 for certain drugs, such as methotrexate.

MISC

• ヒメマスの椎骨における骨強度と骨質の椎骨位置依存性

  河本 千宙, 中居 豪佑, 堀内 秀与, 中村 郁哉, 弘中 翔大, 三友 秀之, 居城 邦治, 佐々木 直樹, 木村 廣美[須田]  日本骨形態計測学会雑誌  33-  (1)  176  -176  2023/05
• ヒメマスとベニザケ幼魚,親魚の生息環境が各骨質,骨強度に及ぼす影響

  河本 千宙, 堀内 秀与, 中村 郁哉, 弘中 翔大, 三友 秀之, 居城 邦治, 木村 廣美[須田]  日本骨形態計測学会雑誌  32-  (1)  S191  -S191  2022/05
• Orientation changes of gold nanorods depending on polymer brush structure

  関澤祐侑, 三友秀之, 与那嶺雄介, 磯野拓也, 田島健次, 佐藤敏文, 居城邦治  ナノ学会大会講演予稿集  20th-  2022
• ヒメマスおよびベニザケ椎骨の骨評価

  堀内 秀与, 弘中 翔大, 中村 郁哉, 河本 千宙, 松尾 保孝, 三友 秀之, 居城 邦治, 木村 廣美[須田]  日本骨形態計測学会雑誌  31-  (2)  S130  -S130  2021/06
• Lyotropic liquid crystalline structure of organic dendron-modified Au nanorods

  Horiai Riko, Yachi Takehiro, Matsubara Masaki, Mitomo Hideyuki, Muramatsu Atsushi, Kanie Kiyoshi  Proceedings of Japanese Liquid Crystal Society Annual meeting  2020-  PB11  2020  

  Formation of nanoparticle(NP)-based three-dimensional periodic structures leads to new functions derived from the structure as well as unique properties of NPs. Modification of NPs with liquid-crystalline (LC) organic dendrons is a powerful method to introduce self-assembling and thermodynamic properties into NPs. Anisotropic-shaped Au nanorods (AuNRs) show unique optical absorption properties derived from both long and short axes. In this study, the dendron-modified AuNRs were developed by hybridization of AuNRs and LC dendrons. The resulting dendron-modified AuNRs show good miscibility to hydrocarbons. Here, the lyotropic liquid crystallinity of the dendron-modified AuNRs in dodecane has been investigated to control their optical properties.
• DNA固定化基板を足場としたロッド状金ナノ粒子の配向化

  三友秀之, 居城邦治  セラミックス  53-  (6)  407  -410  2018/06  [Refereed][Not invited]
  
• ナノポア(ナノサイズの穴)を用いた単分子センシング

  居城邦治, 三友秀之  パリティ Parity  31-  (6)  23  -31  2017/06  [Refereed][Not invited]
  
• 生体分子の集合構造体にならった金ナノ粒子の自己集合

  新倉謙一, 三友秀之, 居城邦治  化学工業  66-  (4)  300  -304  2015/04  [Refereed][Not invited]
  
• 2015年の化学-注目の論文-「可視光を利用したアンモニアの合成」

  MITOMO Hideyuki  月刊化学  70-  (2)  61  -62  2015/02  [Refereed][Not invited]
  
• DNAミメティクス

  三友秀之, 居城邦治  日本画像学会誌  53-  (3)  199  -206  2014/06  [Not refereed][Not invited]
  
• RNase内包ウイルスカプセルの作製と内部でのRNA分解反応

  杉村尚俊, 新倉謙一, 萩原恭二, 三友秀之, 伊藤嘉浩, 澤洋文, 長田義仁, 居城邦治  高分子学会予稿集(CD-ROM)  63-  (1)  2014
• ウイルスカプセルの内部空間での配列特異的RNA分解反応

  杉村尚俊, 新倉謙一, 萩原恭二, 三友秀之, 澤洋文, 居城邦治  高分子学会予稿集(CD-ROM)  63-  (2)  2014
• 生物に学ぶ動的に色を変えるナノ構造材料

  三友秀之, 居城邦治  工業材料  61-  (11)  40  -43  2013/11  [Refereed][Not invited]
  
• Amphiphilic nanoparticles bearing ester functionality and its effect on cellular uptake

  KOBAYASHI Kenya, NIIKURA Kenichi, TAKEUCHI Chie, HAGIWARA Kyoji, MITOMO Hideyuki, NINOMIYA Takahumi, ITO Yoshihiro, OSADA Yoshihito, IJIRO Kuniharu, IJIRO Kuniharu  Abstracts. RIES-Hokudai International Symposium  14th-  2013
• 酵素内包ウイルスカプセルの作製と微小空間での酵素反応

  杉村尚俊, 新倉謙一, 萩原恭二, 三友秀之, 永井健治, 澤洋文, 居城邦治  高分子学会予稿集(CD-ROM)  62-  (2)  2013
• Biomimetic Materials in Imitation of Eye-Opening Colors from Nano-Structure in Nature

  MITOMO Hideyuki, SHIMAMOTO Naonobu, IJIRO Kuniharu  Jitsumu Hyomen Gijutsu  64-  (1)  9  -14  2013/01  [Not refereed][Not invited]
  
• Fabrication of nano- or micro-meter scale pattern on hydrogels

  SHIMAMOTO Naonobu, SHIMAMOTO Naonobu, MITOMO Hideyuki, MITOMO Hideyuki, KAWAMURA Ryu‐zo, KISHI Ryo‐ichi, TANAKA Yoshito, SASAKI Keiji, IJIRO Kuniharu, IJIRO Kuniharu, OSADA Yoshihito  高分子学会予稿集(CD−ROM)  61-  (1)  ROMBUNNO.1M21  2012/05/15  [Not refereed][Not invited]
  
• 多孔性無機微粒子によるゲルの物性制御

  三友秀之, 三友秀之, 佐野健一, 佐野健一, 居城邦治, 居城邦治, 長田義仁  高分子学会予稿集(CD−ROM)  60-  (2 Disk1)  ROMBUNNO.2S03  2011/09/13  [Not refereed][Not invited]
  
• ゲル表面への金属マイクロパターンの作製

  島本直伸, 島本直伸, 三友秀之, 三友秀之, 川村隆三, 川端邦明, 岸良一, 佐野健一, 佐野健一, 居城邦治, 居城邦治, 長田義仁  高分子学会予稿集(CD−ROM)  60-  (2 Disk1)  ROMBUNNO.3PC069  2011/09/13  [Not refereed][Not invited]
  
• Thin film micro grating on hydro-gels for fine measurement

  SHIMAMOTO Naonobu, SHIMAMOTO Naonobu, MITOMO Hideyuki, MITOMO Hideyuki, KAWAMURA Ryuzo, OSADA Yoshihito, IJIRO Kuniharu, IJIRO Kuniharu  Abstr RIES Hokudai Symp  12th-  144-145  2011  [Not refereed][Not invited]
  
• 多孔性無機微粒子によるゲルの高強度化

  三友秀之, 三友秀之, 富永大輝, 佐野健一, 島本直伸, 島本直伸, 居城邦治, 居城邦治, 長田義仁  高分子学会予稿集(CD−ROM)  59-  (2 Disk1)  ROMBUNNO.3J06  2010/09/01  [Not refereed][Not invited]
  
• Strengthening of the Hydrogel with Inorganic Particles

  MITOMO Hideyuki, MITOMO Hideyuki, TOMINAGA Taiki, SANO Ken‐Ichi, IJIRO Kuniharu, IJIRO Kuniharu, OSADA Yoshihito  高分子学会予稿集(CD−ROM)  59-  (1 Disk1)  ROMBUNNO.1M20  2010/05/11  [Not refereed][Not invited]
  
• 水晶発振子上での平二分子の構築とSec 系タンパクの固定化

  古沢宏幸, 森田 之, 三友秀之, 塚崎智也, 森博幸, 伊 昭, 岡畑恵  第31 回日本分子生物学会年会、第81 回日本生化学会大会合同大会、神戸、2008 年12 月9-12 日  2008  [Refereed][Not invited]
  
• 水晶発振子上での平面脂質二分子膜の構築とSec系膜タンパク質の固定化

  古澤宏幸, 森田貴之, 三友秀之, 塚崎智也, 森博幸, 伊藤維昭, 岡畑恵雄  生化学  4T26-5  2008  [Not refereed][Not invited]
  
• 水晶発振子上での膜タンパク質を導入した平面脂質二分子膜の構築

  三友秀之, 古澤宏幸, 塚崎智也, 森博幸, 伊藤維昭, 岡畑恵雄  日本化学会講演予稿集  87th-  (2)  1378  2007/03/12  [Not refereed][Not invited]
  
• 水晶発振子を用いた膜タンパク質の機能解析系の構築

  三友秀之, 古澤宏幸, 塚崎智也, 森博幸, 伊藤維昭, 岡畑恵雄  日本化学会バイオテクノロジー部会シンポジウム講演要旨集  9th-  153  2006/09/19  [Not refereed][Not invited]
  
• 水晶発振子基板上での脂質二分子膜の再構成

  三友秀之, 石津縁, 古澤宏幸, 岡畑恵雄  高分子学会予稿集(CD−ROM)  55-  (2 Disk1)  2PB136  2006/09/05  [Not refereed][Not invited]
  
• Preparation of supported lipid membrane for analyses of membrane proteins on a quartz-crystal microbalance (QCM)

  MITOMO Hideyuki, MITOMO Hideyuki, ISHIZU Yukari, ISHIZU Yukari, FURUSAWA Hiroyuki, FURUSAWA Hiroyuki, TSUKAZAKI Tomoya, MORI Hiroyuki, ITO Koreaki, OKAHATA Yoshio, OKAHATA Yoshio  生化学  A14183(2P-B-198)  2006  [Not refereed][Not invited]
  
• Interaction analysis for a chaperone and a signal recognition particle binding onto a ribosome by using quartz-crystal microbalance (QCM)

  FURUSAWA Hiroyuki, FURUSAWA Yuki, MITOMO Hideyuki, SHIGEMATSU Hideki, UEDA Takuya, OKAHATA Yoshio  生化学  77-  (8)  1023  2005/08/25  [Not refereed][Not invited]
  
• Interaction analysis between a trigger factor and a signal recognition particle on the ribosome

  FURUSAWA YUKI, MITOMO HIDEYUKI, SHIGEMATSU HIDEKI, OKAHATA YOSHIO  日本化学会講演予稿集  85th-  (2)  1192  2005/03/11  [Not refereed][Not invited]
  
• Kinetic analysis of protein-protein interaction on lipid membrane using quartz-crystal microbalance

  MITOMO HIDEYUKI, SHIBATA MASAYOSHI, SHIGEMATSU HIDEKI, KOBATAKE EIRI, OKAHATA YOSHIO  日本化学会講演予稿集  84th-  (2)  1102  2004/03/11  [Not refereed][Not invited]
  
• Expression and Functional Characterization of Human ABC Transporter ABCG2 Variants in Insect Cells

  Toshihisa Ishikawa, Shiho Kasamatsu, Yuko Hagiwara, Hideyuki Mitomo, Ryo Kato, Yasuhiro Sumino  Drug Metabolism And Pharmacokinetics  18-  (3)  194  -202  2003/02/01  [Not refereed][Not invited]
   

  Summary: Hitherto three variant forms of ABCG2 have been documented on the basis of their amino acid moieties (i.e., Arg, Gly, and Thr) at the position 482. In the present study, we have generated those variants of ABCG2 by site-directed mutagenesis and expressed them in Sf9 insect cells. The apparent molecular weight of the expressed ABCG2 variants was 130,000 under non-reductive conditions, whereas it was reduced to 65,000 by treatment with mercaptoethanol. It is suggested that ABCG2 exists in the plasma membrane of Sf9 cells as a homodimer bound through cysteinyl disulfide bond(s). Both ATPase activity and drug transport of ABCG2 variants were examined by using plasma membrane fractions prepared from ABCG2-overexpressing Sf9 cells. The ATPase activity of the plasma membrane expressing ABCG2 (Gly-482) was significantly enhanced by prazosin. In contrast, ABCG2 (Arg-482) transports [ 3H]methotrexate in an ATP-dependent manner however, no transport activity was observed with the other variants (Gly-482 and Thr-482). It is strongly suggested that the amino acid moiety at the position of 482 is critical for the substrate specificity of ABCG2. © 2003, The Japanese Society for the Study of Xenobiotics. All rights reserved.
• 微弱超音波を用いた酵素の活性制御

  星野友, 三友秀之, 川崎剛美, 岡畑恵雄  高分子学会予稿集  51-  (5)  939  2002/05/10  [Not refereed][Not invited]
  
• Effects of Weak Ultrasonic Wave on Glycosidase Activities.

  MITOMO HIDEYUKI, KAWASAKI TAKAYOSHI, OKAHATA YOSHIO  日本化学会講演予稿集  81st-  (2)  901  2002/03/11  [Not refereed][Not invited]
  
• 微弱超音波を用いたβ‐N‐Acetylglucosaminidaseの酵素活性制御

  川崎剛美, 三友秀之, 星野友, 岡畑恵雄  生体触媒化学シンポジウム講演要旨集  5th-  36  2001/12/13  [Not refereed][Not invited]
  

Books etc

• Materials Nanoarchitectonics, From Integrated Molecular Systems to Advanced Devices

  Hideyuki Mitomo, Kuniharu Ijiro (ContributorChapter 7, Metal Nanoarchitectonics: Fabrication of Sophisticated Gold Nanostructures for Functional Plasmonic Devices)
  Elsevier 2023/12 (ISBN: 9780323994729) 137-159
• 金属ナノ粒子、微粒子の合成、調製と最新応用技術

  三友 秀之 (Contributor第７章 第５節 金ナノ粒子の自己組織化と高感度バイオセンサへの展開)
  技術情報協会 2021/10 (ISBN: 9784861048623) 558p 403-411
• バイオミメティクス・エコミメティクス : 持続可能な循環型社会へ導く技術革新のヒント

  三友 秀之 (Contributor第10 章 持続型工業の創成に向けて:ナノ材料とバイオミメティクス)
  シーエムシー出版 2021/01 (ISBN: 9784781315638) xi, 367p 279-289
• Stimuli-Responsive Interfaces -Fabrication and Application-

  Hideyuki Mitomo, Kenichi Niikura, Kuniharu Ijiro (Joint workChapter 8, Stimuli-responsive structure control of gold nanoparticle assembly)
  Springer 2016/11 (ISBN: 9789811024634) 127-145
• 生物模倣技術と新材料・新製品開発への応用

  三友秀之, 居城邦治 (Joint work第7章第1節 生物の持つ発色メカニズムとその応用展開)
  技術情報協会 2014/07 (ISBN: 9784861045363) 702 405-412

Presentations

• Active Control of Plasmonic Nanoparticles Using Polymer Gels  [Invited]

  14th ISAJ ANNUAL SYMPOSIUM ON INTEGRATED SCIENCE FOR A SUSTAINABLE SOCIETY  2023/11  Sapporo  Indian Scientists Association in JAPAN
  
• オリゴエチレングリコール被覆金ナノ粒子の表面特性と機能制御  [Not invited]

  三友秀之, 丹羽萌乃佳, 熊 坤, 与那嶺 雄介, 居城 邦治

  第72回高分子討論会  2023/09  香川大学  高分子学会
  
• オリゴエチレングリコール被覆金ナノ粒子のデザインと表面物性  [Invited]

  三友秀之

  第74回コロイドおよび界面化学討論会  2023/09  信州大学  日本化学会 コロイドおよび界面化学部会
  
• Active Control of Plasmonic Nanoparticles Using Polymers  [Invited]

  Hideyuki Mitomo

  The 13th SPSJ International Polymer Conference  2023/07  Sapporo  The Society of Polymer Science, Japan
  
• Flexible Control of Gold Nanorod Arrangements on Polymer Brush Substrates  [Invited]

  Hideyuki Mitomo

  The 14th Asia-Pacific Conference on Near-field Optics  2023/06  Busan
• Actively configurable gold nanorod array on DNA brushes  [Invited]

  Hideyuki Mitomo

  The 10th Chemical Nanoscience Symposium  2023/05  Newcastle
• Flexibly Configurable Gold Nanorod Arrays Templated on Polymer Brush Substrates  [Invited]

  Hideyuki Mitomo

  MATCON2023  2023/01
• Flexibly Configurable Gold Nanorod Arrays on Polymer Brush Substrates  [Invited]

  Hideyuki Mitomo

  2022 RIES-CEFMS Symposium  2022/12
• Gold Nanorod Arrays with Flexible Structures on Polymer Brush Substrates  [Invited]

  Hideyuki Mitomo

  AsiaNANO 2022  2022/11  Busan
• 高分子ブラシを利用した棒状金ナノ粒子の垂直配列化と配向変化  [Not invited]

  関澤 祐侑, 三友 秀之, 与那嶺 雄介, 磯野 拓也, 田島 健次, 佐藤 敏文, 居城 邦治

  第73回コロイドおよび界面化学討論会  2022/09  広島大学  日本化学会 コロイドおよび界面化学部会
  
• 2次元平面上で構造を制御可能な金ナノロッドアレイの創製  [Not invited]

  三友 秀之, 楊 セイケン, 関澤 祐侑, 与那嶺 雄介, 居城 邦治

  第71回高分子討論会  2022/09  北海道大学  高分子学会
  

Association Memberships

• THE JAPAN SOCIETY OF APPLIED PHYSICS   THE SOCIETY OF POLYMER SCIENCE, JAPAN   THE CHEMICAL SOCIETY OF JAPAN   ナノ学会   

Research Projects

• 標的物質の高効率取込機構を持つ超高感度バイオセンシング技術の創成

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2024/04 -2027/03 

  Author : 三友 秀之, 石 旭, 矢野 隆章
• 金ナノ粒子の表面デザインを駆使したプロテインコロナの光制御法の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2022/06 -2025/03 

  Author : 三友 秀之, 佐藤 信一郎

   

  本研究では、高い光機能性と生体適合性を有する金ナノ粒子を用いたナノ粒子医療の開発に取り組んでいる。ナノ粒子医療においては、粒子が血中を安定に滞留し、対象とする疾患部位に特異的に作用するターゲット能が重要である。しかし、一般的に、ナノ粒子が血中に投与されると粒子の表面に様々なタンパク質が吸着してプロテインコロナを形成し、マクロファージに認識されて排除されたり、目的細胞へのターゲット能が失われたりする。このような課題に対し、これまで吸着性を低減するための表面デザインが検討されてきた。本研究では、一歩進んだ“プロテインコロナを制御する手法”の開発を目指し、粒子の表面デザインについて検討を進めている。具体的には、自身のタンパク質が吸着することで粒子の凝集体形成を抑制し、かつ免疫システムから異物として認識されないようにしながらも、マクロファージが認識するようなタンパク質は吸着せず、さらには、特定の部位に到着した際には光刺激によってターゲット能を発揮できるナノ粒子の創製を目指している。 令和４年度は、研究代表者が開発してきた温度応答性を付与する表面被覆分子による機能化を拡張し、よりオリゴエチレングリコール分子鎖が長い分子と混合することで、粒子表面へのタンパク質の吸着性を制御できることを新たに発見した。また、オリゴエチレングリコールが長い分子と混合したことによって応答温度が上昇することが確認されたが、適切な応答温度への再設定も達成した。つまり、体温付近での鋭敏な温度応答性を維持しながら、タンパク質の吸着性を制御可能な表面デザインを見いだした。結果として、血清をいれた細胞培養液中において、血清タンパク質の吸着による粒子の分散安定化と温度変化に応答した粒子の集合化を両立できることがあきらかになった。
• Development of tunable gold nanostructures for novel nanopore devices

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2021/04 -2024/03 

  Author : 三友 秀之, 斎木 敏治, 矢野 隆章

   

  本研究では、金属ナノ構造体が特定波長の光の照射下で示す表面プラズモン共鳴を利用した生体高分子の高感度検出法として、表面増強ラマン散乱測定基材の開発に取り組んでいる。表面プラズモン共鳴は金属ナノ構造体の中でも鋭利な部分で強く増強され、特に狭いギャップ部位において著しく増強されることが知られているが、その狭いギャップ部位にいかに効率的に測定対象物質を導入できるかが重要な課題となっている。本研究では、独自に開発した「ハイドロゲルを利用して金属ナノ構造体のギャップ距離を変える技術」を基板上に形成したナノポアに組み込むことで、この課題の解決を目指している。具体的には、三角形プレート状ナノ粒子を円形のナノポアに６つ頂点が向き合った形で導入する技術を開発する。さらに、このナノ粒子をハイドロゲルと複合化し、ナノスケールでギャップを制御するシステムへと組み上げる。当該年度においては、気-液あるいは液-液界面における自己組織化の手法を用いて異方性ナノ粒子を並べ、基板上に転写する手法の開発に取り組み、頂点が近接した状態で密に粒子が配置された薄膜を形成することに成功した。一方で、ナノポアにプラズモニックナノ粒子を精密に配置する技術の確立に関しては進行途中であり、検討の余地が残っている。ナノポアへのプラズモニックナノ粒子の精密配置技術の確立については、ポアの孔径や表面の物性など調整しながら検討を進めている。
• Nanoscale photothermometry for thermal analysis

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2020/04 -2023/03 

  Author : 矢野 隆章, 三友 秀之
• ナノ粒子コア型ハイブリッドデンドリマーの異方的形状動的変化に基づく協奏機能の誘起

  日本学術振興会：科学研究費助成事業 基盤研究(A)

  Date (from‐to) : 2019/04 -2023/03 

  Author : 蟹江 澄志, 松原 正樹, 三友 秀之

   

  無機ナノ粒子は，プラズモン共鳴，量子効果，磁気特性など，実に魅力的な性質を示す．これらは，孤立したひとつの「情報」として捉えられる．一方，来たるべき Society5.0 の世界では，「情報」の，動的・有機的な書き換え技術が求められる．すなわち，さまざまな刺激により，動的かつ可逆的に「情報」を書き換え可能とする材料研究がサイエンスとして求められる．ナノ粒子材料の視点に立てば，ナノ粒子の「情報」が，外部刺激により増強，消失，変換，伝搬できれば理想的である．では，如何にすれば実現できるであろうか？本研究では，ナノ粒子表面でのデンドロンのダイナミズムに由来したハイブリッドデンドリマーへの異方的形状の誘起によりナノ粒子の「情報」を動的に外部制御する手法を開発することを目的とした． 本研究では，次の5つの研究項目を掲げ研究を遂行する．【１】機能性無機ナノ粒子をコアとするハイブリッドデンドリマーの設計と合成．【２】オリゴチオフェン型液晶性デンドロンの設計，合成，評価．【３】ハイブリッドデンドリマーからなる液晶性自己組織構造構築・制御法開拓．【４】先端計測によるハイブリッドデンドリマーの液晶性自己組織構造解析．【５】ハイブリッドデンドリマーの材料特性解析・制御． なかでも本年度は特に，【１】から【３】につき，研究代表者および分担者の密接な連携により集中的に材料合成を行った．まず，【１】では，分担者松原と連携し，金，量子ドット，Fe3O4, FePt 球状ナノ粒子をコアとする“液晶性有機無機ハイブリッドデンドリマー”を設計・合成した．一方，分担者三友は主に，COOH 基含有チオールを内部シェルとした単分散金ナノロッドの調製および精製手法の開拓を行った．【２】では，液晶性デンドロンの精密有機合成を行った．また，【３】では，磁気誘導加熱および小角X線散乱回折により特性評価を行った．
• 光刺激に応答して基板上で集合状態が変わる金ナノロッドアレイの創製

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2021/09 -2023/03 

  Author : 三友 秀之

   

  金属ナノ粒子は表面プラズモン共鳴現象と呼ばれるバルク材料とは異なる特性を示す。中でも、棒状の金ナノ粒子（金ナノロッド）は近赤外領域に強い吸収を有し、光アンテナや高感度バイオセンサー、医用応用等への応用で注目されている。この金ナノロッドの性質を制御し、高度に活用するためには、金ナノロッドの配向および集合状態を自在に制御可能にすることが重要である。研究代表者はこれまでに、「DNAブラシ」を利用したシステムに着目し、このDNAブラシに適度な静電相互作用力を賦与した金ナノロッドを吸着させることで、自己組織化的に垂直配向固定化できることを明らかにした。さらに、溶液環境を変えることで基板上で金ナノロッドの配向や集合状態を可逆的に制御できることも明らかにしてきた。一方で、これまでのシステム（溶液環境の変化によるもの）では、位置選択性がない等の課題があり、制御性の高い刺激に応答するシステムへの展開が期待されている。そこで本研究では、制御性の高い刺激である「光照射」による金ナノロッドの集合状態の制御システムを目指している。具体的には、温度応答性を賦与した金ナノロッドを調製し、DNAブラシに導入することで温度変化に応答して状態が制御可能な金ナノロッドアレイを作製する。続いて、金ナノロッドが有する光熱変換機能を利用し、光照射により局所的にナノ粒子を加熱し、その熱をトリガーとして金ナノロッドアレイの状態を可逆的に制御可能であることを実証する。 令和２年度は、研究代表者が開発してきた表面被覆分子によって温度応答性を有する金ナノロッドを調製し、DNAブラシ基板に吸着させた状態でも温度に応答して可逆的に集合・脱集合可能であることを確認した。さらに、表面被覆分子を検討することで、応答温度の調整を行い、適当な温度で応答可能な金ナノロッドアレイの調製に成功した。
• Development of a biosensing system with high sensitivity by the application of triangular gold nanoplates and lipid membranes

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2018/04 -2021/03 

  Author : Mitomo Hideyuki

   

  Our previous study showed that actively tunable metal nanogap structures on hydrogels are useful platform for the biosensing. In this study, to improve this system for a highly sensitive biosensing substrate, an application of triangular gold nanoplates with sharp edges and lipid membranes with a fluidity was investigated. As a result, it is indicated that nanostructures on the hydrogel can rotate and simultaneously form sharp edge assembled structures at a point without a fluid membrane, when their distances become closer. On the other hand, the need of further contrivance for the efficient introduction of target molecules into the hot spots is also indicated. These results provided an important insight for the development of ultra-sensitive biosensing substrates.
• Development of universal nanovaccines based on controlled molecular recognition on the surface of B cells

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2016/04 -2019/03 

  Author : Niikura Kenichi, Nambara Katsuyuki, Tazaki Taiyu, Ijiro Kuniharu, Suzuki Tadaki, Ainai Akira

   

  Our aim is creating new nanoparticle-based vaccines by controlling the immune responses. For this purpose, we investigated the interaction between nanoparticles and cells, and applied nanoparticles as vaccines. Comparison of plate and spherical gold nanoparticles showed a reverse size dependency in terms of cellular uptake. Gold nanorods showed the enhanced adjuvanticity as intranasal influenza vaccines compared to spherical nanoparticles. Our data indicates that a choice of the shape and size is the important factor to induce target immune-responses. As a new nanoparticle-based vaccine design, the surface ligands were synthesized for controlling the orientation of immobilized antigen proteins.
• Development of surface-enhanced Raman scattering substrates with high sensitivity using active gap control system

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

  Date (from‐to) : 2016/04 -2018/03 

  Author : Mitomo Hideyuki

   

  In this study, to fabricate a biosensing substrate with ultra high sensitivity, active control of gold nanostructures on hydrogels was studied. 1. The method, by which gold nanostructures prepared on the silicon substrates was transferred onto the hydrogel, was improved. As a result, gold nanostructures were efficiently transferred onto the hydrogel and the transfer onto the thermoresponsive hydrogel was also succeeded. 2. Active gap control of gold nanostructures on the hydrogel was evaluated by the electron microscopy. It was observed that the gap distances were homogenously changed in a nanometer-scale. This result supports precise control of the gaps is possible using volume change of the hydrogels.
• ウィルスを高感度に検出するサイズふるい効果を有するバイオセンサーの開発

  公益財団法人 寿原記念財団：研究助成

  Date (from‐to) : 2017/04 -2018/03 

  Author : 三友 秀之
• 可変ナノギャップを利用した表面増強ラマン散乱による生体高分子の高感度検出法の開発

  文部科学省：科学研究費補助金（若手研究(B))

  Date (from‐to) : 2016/04 -2018/03 

  Author : 三友 秀之
• 新奇金ナノ構造体修飾方法の開発とナノスケール場の制御による機能創

  公益財団法人 住友財団：2016年度基礎科学研究助成

  Date (from‐to) : 2016/11 -2017/11 

  Author : 三友 秀之
• Nucleic acid-encapsulated virus-like polyhedral structure made by goldnanoplates

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

  Date (from‐to) : 2015/04 -2017/03 

  Author : Niikura Kenichi, Ijiro Kuniharu, Mitomo Hideyuki, Torii Yu, Sugimura Naotoshi

   

  Controlling the self-assemblies of functional nanoparticles is a key technology for development of optical, electronic and medical devices. In this research, we present the pH-responsive coassembly system of gold nanoparticles with external anionic polymers in aqueous solutions. Oligoethyleneglycol-coated gold nanoparticles were coassembled with poly(acrylic acid)s as an external mediator under the acidic condition. The assembly size was tuned by molecular weight of the anionic polymers and the induction of hydrophobic moiety into the polymers changed the responsive pH range.
• DNA の塩基配列選択的メッキによるプラズモニックメタマテリアルの創製

  公益財団法人 野口研究所：野口遵研究助成金

  Date (from‐to) : 2016/04 -2017/03 

  Author : 三友 秀之
• 表面増強ラマン散乱による生体高分子の高感度検出を目指した柔軟に構造制御可能な金ナノ構造体の創製

  公益財団法人 カシオ科学振興財団：研究助成

  Date (from‐to) : 2015/12 -2016/12 

  Author : 三友 秀之
• creation of strengthening functional hydrogel through the incorporation of porous inorganic particles

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

  Date (from‐to) : 2012/04 -2015/03 

  Author : MITOMO Hideyuki

   

  To improve mechanical strength of the hydrogels and to give optical functionality to the gels, two issues were studied in this study. 1. Hydrogels, in which organic polymers and porous inorganic particles were topologically conjugated, were prepared. It was showed that strengthening could be performed with little loss of the extensibility when the particle size is less than 1 um. 2. Metal nanostructures were formed on the solid substrates and they were transferred onto the hydrogel through the in situ polymerization on this substrate. Interparticle distance of the metal nanostructures on the gel could be tuned by the volume change of the hydrogel through the change of swelling state.
• 可動型銀ナノ構造体を用いた生体分子の高感度検出法の開発

  一般財団法人 田中貴金属記念財団：2015年度「貴金属に関わる研究助成金」

  Date (from‐to) : 2015 

  Author : 三友 秀之
• DNAブラシを鋳型とした3次元金属パターンの創製

  田中ホールディングス：2014年度「貴金属に関わる研究助成金」

  Date (from‐to) : 2014 

  Author : 三友 秀之
• 毒素およびウィルスの高感度検出法の開発

  ノーステック財団：フードイノベーション創造支援事業 研究シーズ発掘（札幌フードタレント）補助金

  Date (from‐to) : 2013 

  Author : 三友 秀之
• Fabrication of DNA conjugated gold nanoparticle for single electron devices

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2010 -2012 

  Author : IJIRO Kuniharu, SANO Kenichi, NIIKURA Kenichi, MATSUO Yasutaka, SHIMAMOTO Naonobu, MITOMO Hideyuki

   

  DNA-based nanoparticle assembly is powerful tool for fabrication of nanostructures such as nano-patterning, whereas it is required to prepare nanoparticles in which a discrete and known number of single-stranded oligonucleotides are attached by thiol. We attempted to polymerize single primer-template DNA bound to Au nanoparticles by DNA polymerase, Klenow Fragment exo- (KF-), depending on reaction time. The AFM observation and gel electrophoresis suggest that KF- extended the short primer template bound to Au nanoparticle.
• 膜タンパク質活性のQCM上でのin situ解析系の構築

  日本学術振興会：特別研究院奨励費

  Date (from‐to) : 2004/04 -2007/03 

  Author : 三友 秀之

   

  膜タンパク質はその取り扱いの難しさから、定量的な解析はあまり行われていない。そこで、本研究では膜タンパク質をより定量的に解析するために、水晶発振子マイクロバランス法を用いた解析系の構築を目指した。 タンパク質の分泌や膜タンパク質の脂質膜内への埋め込みにおいて重要な働きをもっているSecYEという膜貫通型タンパク質をターゲットとした。より安定で取り扱いが容易な高度好熱菌由来のTSecYEとTSecYEと相互作用しタンパク質の膜透過行うタンパク質であるTSecAの発現・調製を行った。そして、TSecAを部位特異的にbiotin化してAvidinを吸着させた水晶発振子の基板上に固定化し、界面活性剤中において高度好熱菌のTSecYEおよびアミノ酸をタンデムにつないで発現させたdimer状態のTSecYYEとの相互作用解析を行った。その結果、TSecYEはdimer状態をとることでTSecAと強く相互作用するようになり、TSecAとTSecYEとの結合は1:2の割合で起こることが示唆された。 より天然に近い状態で解析を行うため、膜タンパク質が脂質膜に埋め込まれた状態において基板上に固定化できるように2つの方法を検討した。1つは、界面活性剤中で精製された膜タンパク質を部位特異的に修飾し、その修飾部位を利用して基板に固定化し、その後界面活性剤を脂質膜に置換する方法である。2つめは、基板に脂質分子を固定化し、固定化した脂質分子をアンカーとして脂質膜と膜タンパク質を基板上で再構成する方法である。前者の方法では膜タンパク質の配向性と固定化密度を制御した生体膜の再構成ができ、後者では膜タンパク質の流動性を確保した生体膜の固定化が行え、それぞれ一長一短をもつ2つの固定化方法が確立できたと考えられ、今後いろいろな膜タンパク質の機能解析に適用されることが期待される。

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