研究者データベース

松尾 保孝(マツオ ヤスタカ)
電子科学研究所 共創研究支援部
教授

基本情報

所属

  • 電子科学研究所 共創研究支援部

職名

  • 教授

学位

  • 博士(工学)(北海道大学)

J-Global ID

研究キーワード

  • 微細加工   ナノバイオ   1分子計測(SMD)   ナノ材料   分子認識   表面・界面物性   光物性   DNA   ハニカム構造   自己組織化   ナノワイヤー   LB法   ナノテクノロジー   表面プラズモン共鳴   光ピンセット   生体高分子材料   蛍光顕微鏡   無電解メッキ   ナノ構造   発光   

研究分野

  • ナノテク・材料 / ナノ構造化学
  • ナノテク・材料 / 高分子材料
  • ナノテク・材料 / 機能物性化学
  • ナノテク・材料 / 光工学、光量子科学
  • ナノテク・材料 / ナノバイオサイエンス
  • ナノテク・材料 / ナノ材料科学

職歴

  • 2018年04月 - 現在 北海道大学 電子科学研究所 教授
  • 2010年01月 - 2018年03月 北海道大学 電子科学研究所 准教授
  • 2007年04月 - 2010年12月 北海道大学電子科学研究所 助教
  • 2004年08月 - 2007年03月 北海道大学電子科学研究所 助手
  • 2004年04月 - 2004年07月 日本学術振興会特別研究員
  • 2003年10月 - 2004年03月 北海道大学 研究員
  • 2001年04月 - 2003年09月 科学技術振興機構 研究員

学歴

  •         - 2001年   北海道大学   工学研究科
  •         - 1996年   大阪大学   工学研究科
  •         - 1994年   大阪大学   工学部

所属学協会

  • 応用物理学会 有機分子・バイオナノテクノロジー分科会   高分子学会   日本化学会   応用物理学会   

研究活動情報

論文

  • Hiroshi Yabu, Kosuke Ishibashi, Manjit Singh Grewal, Yasutaka Matsuo, Naoki Shoji, Koju Ito
    Science and Technology of Advanced Materials 23 1 31 - 40 2022年 [査読有り]
     
    The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are important processes for various energy devices, including polymer electrolyte fuel cells, rechargeable metal–air batteries, and water electrolyzers. We herein report the preparation of a rare metal-free and highly efficient ORR/OER electrocatalyst by calcination of a mixture of blood meal and ascidian-derived cellulose nanofibers. The obtained carbon alloys showed high ORR/OER performances and proved to be promising electrocatalysts. The carbon alloys synthesized entirely from biomass resources not only lead to a new electrocatalyst fabrication process but also contribute to CO2 reduction and the realization of a good life-cycle assessment value in fabrication of a sustainable energy device.
  • Hiroshi Yabu, Koki Nakamura, Yasutaka Matsuo, Yutaro Umejima, Haruyuki Matsuyama, Jun Nakamura, Koju Ito
    ACS Applied Energy Materials 4 12 14380 - 14389 2021年12月27日 [査読有り]
     
    The oxygen reduction reaction (ORR) at the cathode is one of the critical bottlenecks in the energy conversion process in polymer electrolyte fuel cells (PEFCs) and metal-air batteries. An iron azaphthalocyanine unimolecular layer (Fe-AZUL) adsorbed onto a carbon substrate exhibited high ORR activity as an alternative of Pt supported on carbon black (Pt/C) electrocatalyst. We herein report the synthesis of various AzPc molecules with different peripheral structures and complex metals, as well as measurements of the ORR activities of catalysts containing the synthesized molecules and carbons. The catalytic activities were characterized by electrochemical analysis, density functional theory (DFT) calculations, and measurements of ionization potential (IP) values. From the results, the IP values on Ketjen Black (KB) were found to be one of the significant indicators for high ORR activities, providing a guideline for the development of high-performance electrocatalysts.
  • Manjit Singh Grewal, Yasutaka Matsuo, Hiroshi Yabu
    New Journal of Chemistry 45 41 19228 - 19234 2021年11月07日 [査読有り]
     
    The sluggish kinetics of the oxygen reduction reaction (ORR) requires highly effective and stable electrocatalysts to boost the reaction. However, conventionally used Pt-based catalysts are expensive and suffer from long-term stability. The present work provides some interesting insights into using heteroatom-doped carbon electrocatalysts prepared from marine biomass cellulose nanocrystals as potential electrocatalysts for an efficient ORR. The proposed simplistic approach provides a substantial synthetic platform for applying an easily obtained bio-derived highly crystalline cellulose material to energy conversion and storage systems.
  • Manjit Singh Grewal, Hiroya Abe, Yasutaka Matsuo, Hiroshi Yabu
    ROYAL SOCIETY OPEN SCIENCE 8 8 2021年08月 [査読有り]
     
    We propose a surface modification of poorly dispersive polytetrafluoroethylene (PTFE) particles via bioinspired polydopamine-polyethyleneimine (PDA-PEI) which conferred PTFE particles a uniform dispersion in aqueous medium. With increasing dopamine concentration in the reaction solution, dispersity of PTFE particles improved and the surface charges of particles changed from negative to positive due to an increase of surface coverage of PDA-PEI layers. Simplicity of the method here outlines an attractive route for surface modification of inert surfaces useful for large-scale applications.
  • Masanaru Nosaka, Kazuma Tsujioka, Yasutaka Matsuo, Takahiro Okamatsu, Toshihiko Arita, Masatsugu Shimomura, Yuji Hirai
    LANGMUIR 37 21 6459 - 6467 2021年06月 [査読有り]
     
    Vulcanized rubber is widely used in a wide range of applications because of its flexibility, durability, sealing properties, and high degree of friction. However, this high degree of friction can also become an issue, as it leads to the wearing and breakage of parts. In this report, we investigated the effects of the vulcanized rubber microstructures on friction force by using simple, anisotropic microstructures. The line and space master microstructures were prepared from a photoresist, and the structures were transferred to PDMS, PSt, and then Ni. After surface modification of the Ni microstructures by TEOS, the vulcanized rubber microstructures were fabricated by a simple hot press process with the TEOS-coated Ni microstructure molds. The structural parameters of the vulcanized rubber line and space microstructures were found to be successfully varied by elongation, and the structural deformations were also investigated by FEM simulations. Measurements of the frictional force of the vulcanized rubber microstructures revealed the friction coefficient was reduced by the surface microstructures and was affected by the directions of the contact because of the microstructure anisotropy. The reason for of these results can be explained by the changes in the contact area and hysteresis friction. These results suggest that the friction coefficients of vulcanized rubbers can be reduced by the simple surface microstructures that are applicable to a wide range of fields.
  • Hiroshi Yabu, Yasutaka Matsuo, Takahiro Yamada, Hirotaka Maeda, Jun Matsui
    Chemistry of Materials 32 23 10176 - 10183 2020年12月08日 [査読有り]
     
    Magnesium silicide (Mg2Si) is one of the few thermoelectric materials that is composed of high Clark number elements and exhibits an optimum temperature near 700 K. The advantage of Mg2Si is that it is composed of universal elements and can be synthesized at low cost. However, it has the disadvantage of low efficiency in converting heat flow to electricity due to its high thermal conductivity. In this paper, Mg vapor annealing of silica-coated 1,2-polybutadiene honeycomb films enables the formation of a Mg2Si honeycomb supported by amorphous carbon. The annealing temperature should be greater than 998 K to obtain Mg2Si honeycombs, and we confirmed through detailed chemical analysis that a silica layer can be converted to a Mg2Si layer via formation of Si. Furthermore, the honeycomb structure eventually reduced the thermal diffusivity even though only a single layer of the honeycomb structure formed on the surface. The obtained Mg2Si honeycombs are good candidates for effective and low-cost thermoelectric materials for use in high-temperature applications.
  • Yali Shi, Qian Li, Yao Zhang, Guoqing Wang, Yasutaka Matsuo, Xingguo Liang, Tohru Takarada, Kuniharu Ijiro, Mizuo Maeda
    JOURNAL OF MATERIALS CHEMISTRY C 8 45 16073 - 16082 2020年12月 [査読有り]
     
    Hierarchical plasmonic nanostructures that embed multiple shape-discrete domains and thereby unique plasmon resonance have implications in detection, diagnostics, and photovoltaics. Despite great progress in self-assembly of gold nanostructures, direct synthesis of hierarchical Au nanostructures that afford dense and steady intrinsic hotspots has remained less explored. This is partially because nanocrystal growth principally yields symmetrical nanocrystals with simple morphologies in monometallic systems. We report on the seeded synthesis of "Au nanograsses" on Au nanoplates that comprise an array of bent Au nanowire and exhibit total light absorption and intrinsically coupled plasmon resonance. The growth of Au nanograsses is achieved through competition between Au deposition and surface ligand passivation, which restricts the deposition of upcoming Au atoms onto the freshly deposited Au surfaces that have not been passivated. By controlling reaction kinetics and ligand passivation, the secondary nanostructures can be tuned from nanowires to nanotubes and near-spherical islands. Theoretical simulations indicate a stronger near-field electromagnetic field and a denser distribution of built-in hotspots of the Au nanograss than the near-spherical nanoisland array. Application of the Au nanograss in single-particle surface-enhanced Raman scattering (SERS) reveals a greatly elevated enhancement effect of the Au nanograss compared to the nanoisland array by nearly one order-of-magnitude.
  • Hiroshi Yabu, Jun Matsui, Yasutaka Matsuo
    LANGMUIR 36 40 12023 - 12029 2020年10月 [査読有り]
     
    Wettability control of porous materials is significant in lateral flow immunoassay, microfluidic systems, microdroplet manipulation, and so on. In this report, formation of metal oxide layers on self-organized polymer honeycomb films to control surface wettability by simple sol-gel coating and UV-O-3 treatment was demonstrated. By the combination of bottom-up and topdown processes, silica thin layers can be formed by retaining their original three-dimensional honeycomb structures. Furthermore, photopatterning of metal oxides on honeycomb films can be achieved by UV irradiation through photomasks. Site-selective wettability control of honeycomb films was realized by patterning silica layers on the surface of the film.
  • 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 2020年08月 [査読有り]
     
    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.
  • Satoshi Nakamura, Hideyuki Mitomo, Yu Sekizawa, Takeshi Higuchi, Yasutaka Matsuo, Hiroshi Jinnai, Kuniharu Ijiro
    LANGMUIR 36 13 3590 - 3599 2020年04月 [査読有り]
     
    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.
  • Shun Uemura, Yasutaka Matsuo, Takahiro Okamatsu, Toshihiko Arita, Masatsugu Shimomura, Yuji Hirai
    ADVANCED ENGINEERING MATERIALS 22 4 2020年04月 [査読有り]
     
    Multifunctional vulcanized rubber microspiked structures are prepared by a simple hot-press process with a fine microstructured Si mold. The vulcanized rubber spiked structures reduce the friction coefficient by concentration of the load on the top of the spikes, as confirmed by a simple calculation of the relationship between the contact area and the friction force. The friction coefficient can also be controlled by elongation of the vulcanized rubber and the rubbing direction due to the changes in the arrangement of the spiked structures from hexagonal to anisotropic linear patterns without deformation of the spike structures. The vulcanized rubber spiked structures show additional functions such as superhydrophobicity and shape memory. The superhydrophobicity is realized by the fine microspiked structures, and the shape-memory effect is generated by the vulcanized rubber properties. Therefore, folded spiked structures can be recovered to their original state by heat treatment, and superhydrophobicity regenerates. These results indicate that the surface microstructures can add further functionality to these materials. The simplicity of the preparation method required for this multifunctional vulcanized rubber offers great possibilities for the creation of superior products as there are many examples of such structural designs in nature.
  • 先進ナノ構造・状態解析共用拠点(北海道大学)
    柴山 環樹, 松尾 保孝, Agus Subagyo, 坂口 紀史, 渡辺 精一
    まてりあ 58 12 758 - 762 2019年12月 [査読有り][招待有り]
  • Hiroya Abe, Yutaro Hirai, Susumu Ikeda, Yasutaka Matsuo, Haruyuki Matsuyama, Jun Nakamura, Tomokazu Matsue, Hiroshi Yabu
    NPG Asia Materials 11 1 57  2019年10月 [査読有り][通常論文]
     
    © 2019, The Author(s). A new class of Pt-free catalysts was designed that included molecular iron phthalocyanine (FePc) derivatives, namely, iron azaphthalocyanine (FeAzPc) unimolecular layers (Fe AzULs) adsorbed on oxidized multiwall carbon nanotubes (oxMWCNTs). FeAzPcs were dissolved in organic solvents such as dimethyl sulfoxide (DMSO), and catalytic electrodes modified with molecularly adsorbed FeAzPcs were successfully prepared. The optimized composition of the catalytic electrodes was determined, and the electrodes exhibited superior activity for the oxygen reduction reaction (ORR) and better durability than conventional FePc catalytic electrodes and commercial Pt/C due to the electron-withdrawing properties of the pyridinic nitrogen in FeAzPcs. The catalytic electrodes that were molecularly modified with FeAzPcs have higher activities than those composed of FeAzPc crystals and oxMWCNTs. To the best of our knowledge, among all of the conventional catalysts based on modified MWCNTs and oxMWCNTs, this catalyst exhibits the highest activity. Unlike other Pt-free catalytic electrodes, the Fe AzUL catalytic electrodes can be prepared by low-cost processing without pyrolysis and are therefore promising catalytic electrode materials for applications, such as polymer electrolyte fuel cells and metal–air batteries.
  • Yuji Hirai, Hiroyuki Mayama, Riku Tamura, Yasutaka Matsuo, Takahiro Okamatsu, Toshihiko Arita, Masatsugu Shimomura
    POLYMER JOURNAL 51 8 721 - 730 2019年08月 [査読有り]
     
    Microstructured surfaces have been attracting a considerable amount of attention for many practical applications, such as superhydrophobic materials. The key issue in everyday applications of superhydrophobic materials based on microstructured surfaces is their durability because most microstructures are prepared with stiff and fragile materials and are easily broken mechanically. In this study, we focused on vulcanized rubber as a flexible and durable hydrophobic material for the fabrication of microstructured surfaces. Superhydrophobic spiky microstructures were simply prepared from vulcanized rubber by using a silicon micromold and compact hot-press equipment. Owing to the elasticity of the vulcanized rubber, the spike-array arrangements on the rubber surface were reversibly deformed by repeated stretching without destruction of the spiky microstructures. Surface wettability was affected by the spike-array arrangements, which can be controlled by stretching concomitantly with the degree of elongation. This phenomenon was theoretically explained by the wettability transition from a Cassie-Baxter to a Wenzel state considering water penetration into the gaps among the spiky microstructures. The results indicated that microstructured vulcanized rubber surfaces can be applicable to a wide variety of fields because of the superior functions derived from their microstructures.
  • Satoru Hamajima, Hideyuki Mitomo, Takeharu Tani, Yasutaka Matsuo, Kenichi Niikura, Masayuki Naya, Kuniharu Ijiro
    NANOSCALE ADVANCES 1 5 1731 - 1739 2019年05月 [査読有り]
     
    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.
  • Quan Sun, Han Yu, Kosei Ueno, Shuai Zu, Yasutaka Matsuo, Hiroaki Misawa
    Opto-Electron. Adv. 2 4 180030  2019年04月 [査読有り][通常論文]
     
    We studied the near-field properties of localized surface plasmon resonances in finite linear gold nanochains using photoemission electron microscopy (PEEM). The localization of the electromagnetic field in the near-field region was mapped at high spatial resolution. By tuning the excitation laser wavelength, we can obtain the near-field spectra, from which the energy splitting between longitudinal (L) and transverse (T) plasmon modes can be revealed. In particular, the L-mode red shifts and the T-mode blue shifts with increasing chain length. The red shift of the L-mode is highly dependent on the gap distance. In contrast, the T-mode almost remains constant within the range of gap distance we investigated. This energy splitting between the L-mode and the T-mode of metallic chains is in agreement with previous far-field measurements, where it was explained by dipole-dipole near-field coupling. Here, we provide direct proof of this near-field plasmon coupling in nanochains via the above-described near-field measurements using PEEM. In addition, we explore the energy transport along the gold nanochains under excitation at oblique illumination via PEEM measurements together with numerical simulations.
  • Chihiro Urata, Roland Hones, Tomoya Sato, Hiroshi Kakiuchida, Yasutaka Matsuo, Atsushi Hozumi
    ADVANCED MATERIALS INTERFACES 6 2 2019年01月 [査読有り]
     
    Textured organogel films showing thermoresponsive (TR)-syneretic and optical behaviors are fabricated based on soft lithography, using micro/nanostructured master moulds, of polydimethylsiloxane infused with polymethylphenylsiloxane (PMPS) as a lubricating oil. The critical syneretic temperature (CST) of the organogels can be arbitrarily tuned in the range of -15-50 degrees C by varying the volume of PMPS. Below the CST, the oil is spontaneously released from the inside of the gel matrices to the topmost surface, and vice versa, and it gradually returns back to the matrices above the CST. In the lubricated state, the textured TR-organogel film surfaces exhibit excellent dynamic hydrophobicity and icephobicity, i.e., ice can be easily removed from the surface without any additional force. Simultaneously, optical properties derived from surface micro/nanotextures, such as diffraction and antireflection, respectively, are clearly observed above the CST and disappear below the CST, because the surface textures are buried by the released PMPS. These unusual TR-surface functionalities are found to be repeatable/switchable for several tens of times.
  • Ueno, Kosei, Yang, Jinghuan, Sun, Quan, Aoyo, Daisuke, Yu, Han, Oshikiri, Tomoya, Kubo, Atsushi, Matsuo, Yasutaka, Gong, Qihuang, Misawa, Hiroaki
    Applied Materials Today 14 159 - 165 2019年 [査読有り][通常論文]
     
    The construction of metallic nanostructures with strong near-field enhancement is becoming increasingly significant for the practical use of plasmonic devices, such as plasmonic sensors and light-energy conversion systems. Importantly, the near-field enhancement effect depends on the plasmon dephasing time. Here, we propose a method for controlling plasmon dephasing time by utilizing plasmonic coupling for stronger near-field enhancement. Ordered arrays of stacked nanogap gold (Au) structures composed of a metal/insulator/metal nanostructure were fabricated by electron beam lithography and dry etching processes on a niobium-doped titanium dioxide substrate. The dark plasmon mode was excited by the near-field coupling between the upper and lower Au nanostructures separated by an alumina layer with a thickness of 15 nm. A strong near-field enhancement effect was induced by the localization of the electromagnetic field between the upper and lower Au nanostructures and the longer plasmon dephasing time based on the excitation of the dark plasmon mode. It is noteworthy that the dephasing time of the dark plasmon mode measured by time-resolved photoemission electron microscopy was extended 3-fold compared with that of the plasmon mode of the Au nanoblock, which can be controlled by the structural design of the stacked nanogap Au structures. (C) 2018 Elsevier Ltd. All rights reserved.
  • Yutaro Hirai, Yasutaka Matsuo, Hiroshi Yabu
    ACS APPLIED NANO MATERIALS 1 9 4980 - 4987 2018年09月 [査読有り]
     
    Metal nanoparticle clusters are regarded as metamaterials, and dispersions of nanoparticle clusters are regarded as metafluids. Surface-enhanced Raman scattering (SERS) from molecules adsorbed on the nanoparticle clusters is one of the notable properties of metafluids. SERS is expected to permit the realization of single-molecule detection in chemical and biological samples, especially cells and tissues. However, most SERS measurements have been done on substrates; local information on cells and tissues have been hard to obtain. SERS active particles can be used to measure the local information on cells. To analyze biological samples using SERS, the SERS substrate should be excitable in the near-infrared (NIR) region to ensure high transparency in biological tissues. Furthermore, transporting the SERS particles to the desired position is crucial for obtaining high resolution. Sizes of SERS-active particles also affect to the resolutions. In this report, gold nanoparticle clusters based on polymer core-shell particles incorporating magnetic Fe3O4 nanoparticles were prepared via a self-assembly method. Structures, LSPR absorption, SERS signals, magnetic responsibility of prepared particles were analyzed by electron microscope, UV-vis spectrum, Raman measurement, and optical microscope observation under magnetic flux, respectively. The enhancement factor of the SERS signal was determined by the size of composited gold nanoparticles. Furthermore, the migration direction of the gold nanoparticle cluster composite particles in aqueous media was successfully controlled by the application of an external magnetic field.
  • Jinjian Wei, Hideyuki Mitomo, Takeharu Tani, Yasutaka Matsuo, Kenichi Niikura, Masayuki Naya, Kuniharu Ijiro
    Langmuir 34 41 12445 - 12451 2018年09月 [査読有り][通常論文]
     
    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.
  • Yutaka Yoshida, Ko Ohnishi, Yasutaka Matsuo, Seiichi Watanabe
    AIP Advances 8 4 045122 - 045122 2018年04月 [査読有り]
  • Ryo Iida, Hideyuki Mitomo, Kenichi Niikura, Yasutaka Matsuo, Kuniharu Ijiro
    Small 14 14 1704230 - 1704230 2018年02月 [査読有り][通常論文]
     
    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 x 14 nm in diameter) coated with a hexa(ethylene glycol) (HEG) derivative form side-by-side assemblies at 30 degrees C (T-A1) as a steady state through dehydration. By further heating to over 40 degrees C (T-A2), 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 x 8 and 54 x 15 nm) also show two-step assembly. Both the T-A1 and T-A2 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.
  • Hideyuki Mitomo, Satoshi Nakamura, Yasunobu Suzuki, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro
    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 17 12 8995 - 9001 2017年12月 [査読有り][通常論文]
     
    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.
  • 平井悠司, 田村陸, 江本智, 下村政嗣, 松尾保孝, 岡松隆裕, 有田稔彦
    日本ゴム協会誌 90 6 277 - 282 一般社団法人 日本ゴム協会 2017年06月 [査読有り][通常論文]
     
    9387
  • Yuji Hirai, Hiroyuki Mayama, Yasutaka Matsuo, Masatsugu Shimomura
    ACS APPLIED MATERIALS & INTERFACES 9 18 15814 - 15821 2017年05月 [査読有り][通常論文]
     
    In nature, there exist many functional water controlling surfaces, such as the water-repellent surface of lotus leaves, the superhydrophobic water-adhesive surface of rose petals, the water-harvesting surface of a beetle's back, and the water-transporting surface of the legs of Ligia exotica. These natural surfaces suggest that surface chemistry and hierarchical structures are essential for controlling the water behavior. We have reported the preparation of superhydrophobic and antireflection silicon nanospike-array structures using self organized honeycomb-patterned films as three-dimensional dry-etching masks. Moreover, the surface wettability of the silicon nanospike-array structures can be easily transformed from superhydrophobic to superhydrophilic by changes in the surface chemistry. In this report, we show the preparation of water-controlling surfaces, such as water-harvesting and water transporting surfaces, by the wettability patterning of silicon nanostructured surfaces. We prepared honeycomb-patterned films for dry-etching masks made from polystyrene and an amphiphilic polymer by casting a chloroform solution. After the fixation of the top layer of the honeycomb-patterned films on a single-crystal silicon substrate, reactive ion etching was performed. The as prepared silicon nanospike-array structure showed superhydrophobicity, and the water contact angles were over 170 degrees. After UV-O-3 treatment with photomasks, only the UV-irradiated surfaces showed superhydrophilicity, suggesting that we can obtain superhydrophobic- and superhydrophilic-patterned surfaces for which the patterns are the same as those of the photomasks. On the basis of these wettability-patterned surfaces, we demonstrated water harvesting by superhydrophilic dot-patterned surfaces and water transportation against gravity by superhydrophilic triangular-patterned surfaces. In particular, we investigated uphill water transport through the motion of droplets on tilting slopes based on the equation of motion. These results suggested that we can obtain superior microfluidic devices suitable for various applications through the use of optional wettability patterns.
  • Yutaro Hirai, Bunji Sawano, Toshihiko Takaki, Yasutaka Matsuo, Hiroshi Yabu
    CHEMISTRY LETTERS 46 5 695 - 698 2017年05月 [査読有り][通常論文]
     
    Metal phthalocyanines (PCs) and their derivatives (PCDs) have been considered for applications in color filters, photovoltaic cells, and photodynamic therapy, owing to their unique optical properties, high chemical and thermal stabilities, and good electron mobility. In addition, since the optical and electronic properties of metal PCDs are improved considerably by reducing their dimensions to the nanoscale, nanocrystals (NCs) of metal PCDs have received much attention. We have previously demonstrated the direct synthesis of CuPCs and ZnPCs in nanomicelles via the UV irradiation of various precursors. In the present study, metal PCDs having various p-conjugated sub-stituents were synthesized using a one-pot UV-assisted process. The resulting metal PCD NCs were found to form stable dispersions in an aqueous PEG solution and these dispersions exhibited significant visible light absorption from 500 to 800nm and high transparency at wavelengths in the non-absorption region.
  • Nakamura Satoshi, Mitomo Hideyuki, Aizawa Miho, Tani Takeharu, Matsuo Yasutaka, Niikura Kenichi, Pike Andrew, Naya Masayuki, Shishido Atsushi, Ijiro Kuniharu
    ACS OMEGA 2 5 2208 - 2213 2017年05月 [査読有り][通常論文]
     
    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.
  • Takashi Endo, Yoshihiro Doi, Makoto Wakeshima, Keita Suzuki, Yasutaka Matsuo, Keitaro Tezuka, Takuya Ohtsuki, Yue Jin Shan, Yukio Hinatsu
    INORGANIC CHEMISTRY 56 5 2459 - 2466 2017年03月 [査読有り]
     
    The synthesis, crystal structures, photoluminescence, and magnetic properties of the melilite-type oxysulfide Sr2MnGe2S6O were investigated. This compound crystallizes in the melilite structure with space group P4 ($) over bar2(1)m, in which two kinds of anions, S2- and O2-, occupy different crystallographic sites in an ordered manner. The temperature dependence of the magnetic susceptibility of Sr2MnGe2S6O shows a broad peak due to a two-dimensional magnetic interaction between Mn ions in the ab plane. The specific heat data show that this compound has an antiferromagnetic transition temperature (T-N = 15.5 K) that is much higher than that of the oxide analogue Sr2MnGe2O7 (T-N = 4.4 K). DFT calculations showed that the magnetic interaction is enhanced by covalency in the Mn-s bonding.
  • Han Yu, Quan Sun, Jinghuan Yang, Kosei Ueno, Tomoya Oshikiri, Atsushi Kubo, Yasutaka Matsuo, Qihuang Gong, Hiroaki Misawa
    OPTICS EXPRESS 25 6 6883 - 6894 2017年03月 [査読有り][通常論文]
     
    We investigated the grating effect in complex gold dolmen structures, in which multiple plasmon modes are present due to plasmon hybridization, experimentally from both the far field and the near field. In particular, the near-field properties were investigated using photoemission electron microscopy, and it was demonstrated that two hybridized plasmon modes on the dolmen structures could be influenced by the grating effect. For comparison, we also investigated the grating effect in arrays of simple nanoblocks and heptamer structures, which were supposed to support a strong bright plasmon mode and a strong dark plasmon mode, respectively, in the near field. We found that the spectral responses of the two hybridized modes on the dolmen structures as the pitch size changed evolved in a manner similar to that of the bright dipole mode on the nanoblocks, whereas the dark mode on the heptamer structures is less sensitive to the pitch size. (C) 2017 Optical Society of America
  • Katsuyuki Nambara, Kenichi Niikura, Hideyuki Mitomo, Takafumi Ninomiya, Chie Takeuchi, Jinjian Wei, Yasutaka Matsuo, Kuniharu Ijiro
    Langmuir 32 47 12559 - 12567 2016年11月 [査読有り][通常論文]
     
    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.
  • Hiroshi Yabu, Jun Matsui, Mitsuo Hara, Shusaku Nagano, Yasutaka Matsuo, Yuki Nagao
    Langmuir 32 37 9484  American Chemical Society ({ACS}) 2016年09月 [査読有り][通常論文]
  • Iida Ryo, Mitomo Hideyuki, Matsuo Yasutaka, Niikura Kenichi, Ijiro Kuniharu
    JOURNAL OF PHYSICAL CHEMISTRY C 120 29 15846 - 15854 2016年07月28日 [査読有り][通常論文]
  • Takeshi Tayagaki, Yusuke Hoshi, Yuji Hirai, Yasutaka Matsuo, Noritaka Usami
    JAPANESE JOURNAL OF APPLIED PHYSICS 55 5 52302  2016年05月 [査読有り][通常論文]
     
    We demonstrated the fabrication of modulated surface nanostructures as a new surface texture design for thin wafer solar cells. Using a combination of conventional alkali etching and colloidal lithography, we fabricated surface textures with micrometer and nanometre scales on a Si substrate. These modulated surface nanostructures exhibit reduced surface reflection in a broad spectral range, compared with conventional micrometer textures. We investigated optical absorption using a rigorous coupled wave analysis simulation, which revealed a significant reduction in surface reflection over a broad spectral range and efficient light trapping (comparable to that of conventional micrometer-scale textures) for the modulated nanostructures. We found that the modulated surface nanostructures have a high potential of improving the performance of thin wafer crystalline Si solar cells. (C) 2016 The Japan Society of Applied Physics
  • Wei Jinjian, Niikura Kenichi, Higuchi Takeshi, Kimura Takashi, Mitomo Hideyuki, Jinnai Hiroshi, Joti Yasumasa, Bessho Yoshitaka, Nishino Yoshinori, Matsuo Yasutaka, Ijiro Kuniharu
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 138 10 3274 - 3277 2016年03月16日 [査読有り][通常論文]
  • Mitomo Hideyuki, Horie Kenta, Matsuo Yasutaka, Niikura Kenichi, Tani Takeharu, Naya Masayuki, Ijiro Kuniharu
    ADVANCED OPTICAL MATERIALS 4 2 259 - 263 2016年02月 [査読有り][通常論文]
  • Mitomo Hideyuki, Eguchi Asumi, Suzuki Yasunobu, Matsuo Yasutaka, Niikura Kenichi, Nakazawa Kohji, Ijiro Kuniharu
    JOURNAL OF BIOMEDICAL NANOTECHNOLOGY 12 2 286 - 295 2016年02月 [査読有り][通常論文]
     
    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.
  • Saito Yuta, Higuchi Takeshi, Jinnai Hiroshi, Hara Mitsuo, Nagano Shusaku, Matsuo Yasutaka, Yabu Hiroshi
    Macromolecular Chemistry and Physics 217 6 726 - 734 2016年 [査読有り][通常論文]
  • Yu Han, Sun Quan, Ueno Kosei, Oshikiri Tomoya, Kubo Atsushi, Matsuo Yasutaka, Misawa Hiroaki
    Acs Nano 10 11 10373 - 10381 2016年 [査読有り][通常論文]
  • Sun Quan, Yu Han, Ueno Kosei, Kubo Atsushi, Matsuo Yasutaka, Misawa Hiroaki
    Acs Nano 10 3 3835 - 3842 2016年 [査読有り][通常論文]
  • Fano resonances on gold nano dolmen structures probed by photoemission electron microscopy
    Han,Yu, Quan,Sun, Ueno,Kosei, Kubo,Atsushi, Matsuo,Yasutaka, Misawa,Hiroaki
    Pacifichem 2015 2015年12月 [査読無し][通常論文]
  • Wang Guoqing, Mitomo Hideyuki, Matsuo Yasutaka, Niikura Kenichi, Maeda Mizuo, Ijiro Kuniharu
    JOURNAL OF COLLOID AND INTERFACE SCIENCE 452 224 - 234 2015年08月15日 [査読有り][通常論文]
     
    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.
  • Masaaki Kanahara, Hiroki Satoh, Takeshi Higuchi, Atsushi Takahara, Hiroshi Jinnai, Koji Harano, Satoshi Okada, Eiichi Nakamura, Yasutaka Matsuo, Hiroshi Yabu
    Particle & Particle Systems Characterization 32 4 401  Wiley-Blackwell 2015年04月 [査読有り][通常論文]
  • Hideyuki Mitomo, Yukie Watanabe, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro
    Chem. Asian. J 10 2 455 - 460 2015年02月 [査読有り][通常論文]
     
    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.
  • KUZUYA, Akinori, KAINO, Masafumi, HASHIZUME, Mirai, MATSUMOTO, Kazuki, UEHARA, Takeaki, MATSUO, Yasutaka, MITOMO, Hideyuki, NIIKURA, Kenichi, IJIRO, Kuniharu, OHYA, Yuichi
    Polymer Journal 47 (2) 177-182 2 177 - 182 2014年12月17日 [査読無し][通常論文]
     
    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.
  • Masaaki Kanahara, Hiroki Satoh, Takeshi Higuchi, Atsushi Takahara, Hiroshi Jinnai, Koji Harano, Satoshi Okada, Eiichi Nakamura, Yasutaka Matsuo, Hiroshi Yabu
    Particle & Particle Systems Characterization 32 4 441 - 447 Wiley-Blackwell 2014年11月 [査読有り][通常論文]
  • Yutaka Yoshida, Kazuya Oosawa, Jyunya Wajima, Seiichi Watanabe, Yasutaka Matsuo, Takahiko Kato
    APPLIED SURFACE SCIENCE 307 24 - 27 2014年07月 [査読無し][通常論文]
     
    We report a technique for formation of two-dimensional (2D) nanodot (ND) patterns on gaillium antimoide (GaSb) using a nanosecond pulsed laser irradiation with 532 nm wavelength. The patterns have formed because of the interference and the self-organization under energy deposition of the laser irradiation, which induced the growth of NDs on the local area. The NDs are grown and shrunken in the pattern by energy depositions. In the laser irradiation with average laser energy density of 35 mJ cm(-2), large and small NDs are formed on GaSb surface. The large NDs have grown average diameter from 160 to 200 nm with increase of laser pulses, and the small NDs have shrunken average diameter from 75 to 30 nm. The critical dot size is required about 107 nm for growth of the NDs in the patterns. Nanosecond pulsed laser irradiation can control the self-organized ND size on GaSb in air as a function of the laser pulses. (c) 2014 Elsevier B.V. All rights reserved.
  • Revealing higher order surface plasmon resonances and their dynamics by PEEM
    Quan,Sun, Han,Yu, Kosei,Ueno, Kubo,Atsushi, Yasutaka,Matsuo, Hiroaki,Misawa
    第61回応用物理学会春季学術講演会 講演予稿集 2014年03月 [査読無し][通常論文]
  • Daisuke Ishii, Hiroko Horiguchi, Yuji Hirai, Hiroshi Yabu, Yasutaka Matsuo, Kuniharu Ijiro, Kaoru Tsujii, Tateo Shimozawa, Takahiko Hariyama, Masatsugu Shimomura
    Scientific Reports 3 3024 - 3024 Nature publishing group 2013年10月 [査読有り][通常論文]
     
    Some small animals only use water transport mechanisms passively driven by surface energies. However, little is known about passive water transport mechanisms because it is difficult to measure the wettability of microstructures in small areas and determine the chemistry of biological surfaces. Herein, we developed to directly analyse the structural effects of wettability of chemically modified biological surfaces by using a nanoliter volume water droplet and a hi-speed video system. The wharf roach Ligia exotica transports water only by using open capillaries in its legs containing hair-and paddle-like microstructures. The structural effects of legs chemically modified with a self-assembled monolayer were analysed, so that the wharf roach has a smart water transport system passively driven by differences of wettability between the microstructures. We anticipate that this passive water transport mechanism may inspire novel biomimetic fluid manipulations with or without a gravitational field.
  • 三友秀之, 渡辺雪江, 松尾保孝, 新倉謙一, 居城邦治
    高分子論文集 70 7 337 - 340 2013年07月 [査読有り][通常論文]
  • Kenichi Niikura, Naoki Iyo, Yasutaka Matsuo, Hideyuki Mitomo, Kuniharu Ijiro
    ACS Appl. Mater. Interfaces 5 9 3900 - 3907 2013年04月 [査読有り][通常論文]
     
    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.
  • Niikura K, Sugimura N, Musashi Y, Mikuni S, Matsuo Y, Kobayashi S, Nagakawa K, Takahara S, Takeuchi C, Sawa H, Kinjo M, Ijiro K
    Mol Biosyst. 9 3 501 - 507 2013年03月 [査読有り][通常論文]
  • Hideyuki Mitomo, Yukie Watanabe, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro
    KOBUNSHI RONBUNSHU 70 7 337 - 340 2013年 
    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.
  • Analysis of herbal medicine coptis by Surface Enhanced Raman scattering Spectroscopy
    Kyouji Honma, Yasutaka Matsuo, Kuniharu Ijiro, Hiromi Kimura-Suda
    Proc. of CIF’13 “Biomimetics, Photonics Sensing and Networks” Eds. O. Karthaus and M. Kawase, PWC Pub 87 - 89 2013年 [査読有り][通常論文]
  • Q. Sun, K. Ueno, H. Yu, A. Kubo, Y. Matsuo, H. Misawa
    Light: Science & Applications 2 e118 - 1-e118-8 Nature Publishing Group 2013年 [査読有り][通常論文]
     
    Localized surface plasmon resonance (LSPR) can be supported by metallic nanoparticles and engineered nanostructures. An understanding of the spatially resolved near-field properties and dynamics of LSPR is important, but remains experimentally challenging. We report experimental studies toward this aim using photoemission electron microscopy (PEEM) with high spatial resolution of sub-10 nm. Various engineered gold nanostructure arrays (such as rods, nanodisk-like particles and dimers) are investigated via PEEM using near-infrared (NIR) femtosecond laser pulses as the excitation source. When the LSPR wavelengths overlap the spectrum of the femtosecond pulses, the LSPR is efficiently excited and promotes multiphoton photoemission, which is correlated with the local intensity of the metallic nanoparticles in the near field. Thus, the local field distribution of the LSPR on different Au nanostructures can be directly explored and discussed using the PEEM images. In addition, the dynamics of the LSPR is studied by combining interferometric time-resolved pump-probe technique and PEEM. Detailed information on the oscillation and dephasing of the LSPR field can be obtained. The results identify PEEM as a powerful tool for accessing the near-field mapping and dynamic properties of plasmonic nanostructures.
  • Yabu Hiroshi, Saito Yuta, Shimomura Masatsugu, Matsuo Yasutaka
    Journal of Materials Chemistry C 1 8 1558 - 1561 2013年 [査読有り][通常論文]
     
    7533
  • Wang Guoqing, Mitomo Hideyuki, Matsuo Yasutaka, Shimamoto Naonobu, Niikura Kenichi, Ijiro Kuniharu
    JOURNAL OF MATERIALS CHEMISTRY B 1 43 5899 - 5907 2013年 [査読有り][通常論文]
     
    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.
  • Guoqing Wang, Ayako Ishikawa, Asumi Eguchi, Yasunobu Suzuki, Shukichi Tanaka, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro
    CHEMPLUSCHEM 77 7 592 - 597 2012年07月 [査読有り][通常論文]
     
    Although progress has been made in the construction of single-electron devices (SEDs), few of the reported approaches have proved practically applicable, mainly owing to their cost-ineffectiveness and need for sophisticated instrumentation. Herein, a conceptually new method for fabricating SEDs through the metallization of divalent DNA-nanoparticle conjugates is described. Specifically, divalent DNA copolymers that are conjugated to gold nanoparticles (AuNP) were synthesized by application of the enzymatic extension of DNA conjugated on quantum-sized AuNPs. This conjugate structure allows the distance between the resulting poly(dG)-poly(dC) and the AuNP to be controlled by an ssDNA spacer. To afford poly(dG)-poly(dC) sequence-specific metal deposition, Cisplatin capable of specific chemisorption on the poly(dG)-poly(dC) is incubated with the divalent DNA copolymerAuNP conjugates, followed by reduction of the Cisplatin to Pt metal at base resolution. As a result, AuNPs separated from the Pt electrodes by the ssDNA barriers in a single conjugate could be created as a double-tunnel junction for SEDs. This study is thought to be an important step toward the programmable organization of DNA for use in SEDs.
  • Shota Sekiguchi, Kenichi Niikura, Yasutaka Matsuo, Kuniharu Ijiro
    LANGMUIR 28 13 5503 - 5507 2012年04月 [査読無し][通常論文]
     
    Surface ligand molecules enabling gold nanoparticles to disperse in both polar and nonpolar solvents through changes in conformation are presented. Gold nanoparticles coated with alkyl-head-capped PEG derivatives were initially well dispersed in water through exposure of the PEG residue (bent form). When chloroform was added to the aqueous solution of gold nanoparticles, the gold nanoparticles were transferred from an aqueous to a chloroform phase through exposure of the alkyl-head residue (straight form). The conformational change (bent to straight form) of immobilized ligands in response to the polarity of the solvents was supported by NMR analyses and water contact angles.
  • Shota Sekiguchi, Kenichi Niikura, Yasutaka Matsuo, Shige H. Yoshimura, Kuniharu Ijiro
    RSC ADVANCES 2 4 1656 - 1662 2012年 [査読無し][通常論文]
     
    The nuclear pores located on the nuclear envelope work as a selective barrier to nuclear import. The transport of large cargo molecules (larger than similar to 40 kD) into the nucleus generally requires the aid of nuclear transport proteins, such as importins, which bind to nuclear localization signal (NLS) sequences in the cargo molecules and transport these molecules into the nucleus through the nuclear pore. In our previous paper, we showed that maltotriose(Glc(3))-displaying quantum dots (QDs) can pass through the nuclear pore in digitonin-treated HeLa cells. The aim of this study is to clarify the mechanism of the nuclear import of maltooligosaccharide-displaying QDs (maltooligo-QDs). We prepared maltopentaose(Glc(5)) and maltoheptaose(Glc(7))-QDs in addition to Glc(3)-QDs. The effect of the number of glucose units in the maltooligosaccharide on the rate of nuclear import of QDs has been explored by confocal laser scanning microscopy (CLSM). Further, we analyzed that the direct interactions of maltooligo-QDs to an internal protein in the nuclear pore (Nucleoporin62) using a surface plasmon resonance (SPR) system. We found that maltooligo-QDs with more than three glucose units (Glc(3), Glc(5) and Glc(7)-QDs) rapidly entered the cellular nucleus, and had a higher affinity to nucleoporin62 than those of PEG and Glc(1)-QDs. These data indicate that the interaction between nuclear pores and carbohydrates is the driving force behind the nuclear import of maltooligo-QDs.
  • Keita Nagakawa, Kenichi Niikura, Tadaki Suzuki, Yasutaka Matsuo, Manabu Igarashi, Hirofumi Sawa, Kuniharu Ijiro
    CHEMISTRY LETTERS 41 1 113 - 115 2012年01月 [査読無し][通常論文]
     
    This manuscript describes the synthesis of virus capsid protein-coated Au nanoparticle (VP-AuNP) without the use of the inherent self-assembly of virus proteins into virus particles. Covalent binding between Au and cysteines in the virus proteins keep the cell-surface binding sites on the external surface. Based on this method, various sizes of VP-AuNP can be created in a similar manner to native virus particles. We clarified the optimum size of the VP-AuNP for internalization into cells.
  • Guoqing Wang, Hirofumi Tanaka, Liu Hong, Yasutaka Matsuo, Kenichi Niikura, Masuhiro Abe, Kazuhiko Matsumoto, Takuji Ogawa, Kuniharu Ijiro
    JOURNAL OF MATERIALS CHEMISTRY 22 27 13691 - 13697 2012年 [査読無し][通常論文]
     
    The rapid development of DNA nanotechnology over the past decade has enabled the self-assembly of conducting building blocks towards the construction of conductive nanowires with potential applications in electronic nanodevices. To date, however, construction of nanostructures with novel electrical properties via DNA templating remains poorly explored. Here, we show that DNA can be used as a guiding template for the fabrication of polyaniline nanowires and gold nanoparticle (AuNP)-polyaniline-alternated hybrid nanowires, both of which exhibit novel electrical properties as characterized by point-contact current imaging atomic force microscopy (PCI-AFM). Specifically, the DNA-templated polyaniline nanowires exhibit Schottky emission-dominated conduction as well as a rectification effect, while the current-voltage (I-V) behaviours of the DNA-templated AuNP-polyaniline hybrid nanowires were found to be attributable to Coulomb blockade effects, probably due to the fact that the configuration of the hybrid nanowires resembles that of a one-dimensional array of multiple tunnel junctions. Given the facile and low-cost self-assembly technique, the present work is of fundamental and technological importance to the fabrication of one-dimensional nanodevices capable of novel charge transport.
  • Shota Sekiguchi, Kenichi Niikura, Naoki Iyo, Yasutaka Matsuo, Asumi Eguchi, Takakazu Nakabayashi, Nobuhiro Ohta, Kuniharu Ijiro
    ACS APPLIED MATERIALS & INTERFACES 3 11 4169 - 4173 2011年11月 [査読無し][通常論文]
     
    A simple approach to the creation of colloidal assemblies is in high demand for the development of functional devices. Here, we present the preparation of CdTe-QD (quantum dot) networks in as little as I day simply by pH modification without the use of oxidants. The QD network was tractable in water and casting from a droplet produced a porous networked film on both hydrophobic and hydrophilic solid substrates. Further, we found that citrate-protected gold nanoparticles (AuNPs, d = 5 nm) could be incorporated into the QD networks to afford a QD/Au composite network, and that the fluorescence from the QDs was largely decreased by the addition of a small proportion of AuNPs (QD:AuNP = 99.4:0.6), probably due to the efficient charge transfer through the network. These data indicate that our method is suitable for application to the creation of metal/QD hybrid materials that can be integrated into wet-based processes.
  • Zheyu Li, Kai Sun, Misato Sunayama, Yasutaka Matsuo, Vygantas Mizeikis, Ryoko Araki, Kosei Ueno, Masumi Abe, Hiroaki Misawa
    JOURNAL OF CHROMATOGRAPHY A 1218 7 997 - 1003 2011年02月 [査読無し][通常論文]
     
    High efficiency and high-purity fraction collection is highly sought in analysis of fragments-of-interest from selective polymerase chain reaction (PCR) products generated by High Coverage Gene Expression Profiling (HiCEP) methods. Here we demonstrate a new electrophoretic chip device enabling automatic high-efficient fractionation of multiple ssDNA target fragments during a run of separation. We used thoroughly isolated extraction channels for each selected target to reduce the risk of cross-contamination between targets due to cross-talk of extraction channels. Fragments of 35, 108 and 138 b, were successfully isolated, then the recovery was PCR-amplified and assessed by capillary electrophoresis (CE) analysis. Total impurity level of the targets due to unwanted fragments of 0.7%, 2% and 6% respectively, was estimated. Difficulties in collecting multiple target factions are due to band diffusion and DNA adsorption to the walls for the fragments in the separation channel, which is generated by transferring the DNA target fraction from the extraction section to the target reservoir. Therefore, we have carefully measured band broadening and analyzed its influence on the separation resolution due to the delay. (C) 2010 Elsevier B.V. All rights reserved.
  • Guoqing Wang, Takashi Nishio, Masato Sato, Ayako Ishikawa, Katsuyuki Nambara, Keita Nagakawa, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro
    CHEMICAL COMMUNICATIONS 47 33 9426 - 9428 2011年 [査読無し][通常論文]
     
    We demonstrate a facile approach for converting AgCl to functional silver nanoparticles (AgNPs) via photoreduction in the presence of DNA. The resulting AgNPs are biofunctionalized, and exhibit photostable luminescence and DNA-specific Raman signatures, showing high potential for use in DNA-directed recognition and advanced bioimaging.
  • Kenichi Niikura, Katsuyuki Nambara, Takaharu Okajima, Ryosuke Kamitani, Shin Aoki, Yasutaka Matsuo, Kuniharu Ijiro
    ORGANIC & BIOMOLECULAR CHEMISTRY 9 16 5787 - 5792 2011年 [査読無し][通常論文]
     
    In our previous paper, secondary-amine appended cationic polymer 1 was used as a scaffold to display artificial receptors on a cell surface (R. Kamitani et al., ChemBioChem, 2009, 10, 230). This polymer can be retained on the cell surface for more than 30 min before being slowly internalized into the cells. In this study, our aim is to achieve the efficient internalization of quantum dots (QDs) into target cells via artificial receptors on the polymer. As a receptor molecule, N-acetylglucosamine (GlcNAc) moieties were introduced into the polymer, and GlcNAc binding protein-displaying QDs were used as a ligand. We found that ligand-presenting QDs could be internalized effectively into cells via polymer-mediated endocytosis, whereas QDs were not internalized into untreated cells. These data suggest that our method based on cell-surface engineering using polymers affords a new approach to the delivery of various poorly permeable nanoparticles into cells.
  • Yuji Hirai, Hiroshi Yabu, Yasutaka Matsuo, Kuniharu Ijiro, Masatsugu Shimomura
    Macromolecular Symposia 295 1 77 - 80 2010年09月 [査読無し][通常論文]
     
    Self-organized honeycomb-patterned polymer films were prepared by using condensed water droplet arrays as templates. Porous polymer masks for dry etching were easily prepared on Si substrates by peeling off the honeycombpatterned films. After dry etching, hexagonally-arranged micro-pores were formed on the surface of Si substrates. © 2010 WILEY-VCH Verlag GmbH& Co.
  • Kenichi Niikura, Katsuyuki Nambara, Takaharu Okajima, Yasutaka Matsuo, Kuniharu Ijiro
    LANGMUIR 26 12 9170 - 9175 2010年06月 [査読無し][通常論文]
     
    A series of FITC-labeled hydrophobic molecules (1-8) were prepared, and their cellular uptakes have been investigated using cell-cycle-synchronized HeLa cells. The cellular membrane permeability of compounds strongly depended on both the chemical structure and the cell-cycle phase. In the G1/S phase, branched hydrocarbon-containing 3 and cis-olefin-containing 2 and 8 were efficiently internalized into cells by passive diffusion. In contrast, linear alkyl chain-containing 1 and 7 were retained on the membrane without rapid internalization. In the M phase, rapid permeation was suppressed for all molecules.
  • Noriko Ohtake, Kenichi Niikura, Tadaki Suzuki, Keita Nagakawa, Shintaro Mikuni, Yasutaka Matsuo, Masataka Kinjo, Hirofumi Sawa, Kuniharu Ijiro
    CHEMBIOCHEM 11 7 959 - 962 2010年05月 [査読無し][通常論文]
  • Takashi Nishio, Kenichi Niikura, Yasutaka Matsuo, Kuniharu Ijiro
    CHEMICAL COMMUNICATIONS 46 47 8977 - 8979 2010年 [査読無し][通常論文]
     
    Fluorinated tetraethylene glycol-stabilized Au nanoparticles (FTEG-AuNPs) were well-dispersed in general polar organic solvents, such as methanol (MeOH) and THF. The cast film of FTEG-AuNPs on a TEM grid and a glass substrate was found to form a highly ordered 3D-superlattice assembly, whereas tetraethylene glycol-stabilized AuNPs (TEG-AuNPs) provide an amorphous AuNP aggregation. These data indicate that the fluorine feature on the surface of the FTEG-AuNPs is critical for the nanostructured assembly.
  • Yuji Hirai, Hiroshi Yabu, Yasutaka Matsuo, Kuniharu Ijiro, Masatsugu Shimomura
    CHEMICAL COMMUNICATIONS 46 13 2298 - 2300 2010年 [査読無し][通常論文]
     
    Silver spike arrays with triangular sharp edges were prepared by using a self-organization process based on the condensation of water droplets and the vapor deposition process. Strongly enhanced Raman scattering of rhodamine 6G on the spike arrays were shown.
  • Hiroshi Yabu, Yasutaka Matsuo, Kuniharu Ijiro, Fumiaki Nishino, Toshihiko Takaki, Masahiro Kuwahara, Masatsugu Shimomura
    ACS APPLIED MATERIALS & INTERFACES 2 1 23 - 27 2010年01月 [査読無し][通常論文]
     
    Honeycomb-patterned polymer films prepared by the simple casting of a polymer solution under humid conditions were used as templates for metal microdot arrays formed on shrinkable polymer substrates by metal sputtering. After thermal shrinkage of the substrate, the periodicity of the metal microdots was reduced. in addition, microwrinkles were formed on the metal microdots. The wavelength and arrangement of the microwrinkles were changed with the metal sputtering time and the diameter of the metal microdots. A clear confinement effect was observed in the formation of the microwrinkles.
  • Yuji Hirai, Hiroshi Yabu, Yasutaka Matsuo, Kuniharu Ijiro, Masatsugu Shimomura
    JOURNAL OF MATERIALS CHEMISTRY 20 48 10804 - 10808 2010年 [査読無し][通常論文]
     
    We demonstrate here a creation of a novel biomimetic bi-functional surface by using dry etching of silicon with a self-organized porous polymer. The novel silicon structures with hierarchical nanospike-array structures covered with fluorocarbons were fabricated by dry etching of silicon through the porous polymer masks. The antireflection and superhydrophobic properties were realized due to their large surface areas and low surface energies. These masks and silicon substrates offer great advantages and are suitable for various practical applications, including high efficiency solar cells.
  • Kenichi Niikura, Keita Nagakawa, Noriko Ohtake, Tadaki Suzuki, Yasutaka Matsuo, Hirofumi Sawa, Kuniharu Ijiro
    BIOCONJUGATE CHEMISTRY 20 10 1848 - 1852 2009年10月 [査読有り][通常論文]
     
    We propose a new approach to optical virus detection, based on the spatial assembly of gold nanoparticles on the surface of viruses. Since JC virus-like particles (VLPs) comprise a repeating viral capsid protein that binds to sialic acid, the conjugation of sialic acid-linked Au particles with VLPs enables the spatial arrangement of Au particles on the VLP surface. This structure produced a red shift in the absorption spectrum due to plasmon coupling between adjacent Au particles, leading to the, construction of an optical virus detection system. Our system depends not on the simple cross-linking of VLPs and Au particles, but on an ordered Au structure covering the entire surface of the VLPs and can be applied to virus detection systems using the inherent ligand recognition of animal viruses.
  • Masaru Tanaka, Hirokazu Sato, Yugo Sasaya, Suguru Horinouchi, Jun-ichi Hotta, Yasutaka Matsuo, Kuniharu Ijiro, Keiji Sasaki, Masatsugu Shimomura
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS 505 1 457 - 468 2009年 [査読有り][通常論文]
     
    This study describes the preparation of biocompatible patterned surfaces by a two-photon absorption technique. We have synthesized poly(2-methoxyethyl acrylate) copolymers, which exhibit biocompatibility and photocrosslinking moiety. Fabrication resolution can be controlled in the sub-micrometer range by changing the laser power, photoinitiator concentration, and scanning speed. The patterned surfaces showed excellent human platelet compatibility. Biocompatible patterned surfaces can be used in various medical devices, implants, biosensor chips, and tissue engineering scaffolds.
  • Ryosuke Kamitani, Kenichi Niikura, Takaharu Okajima, Yasutaka Matsuo, Kuniharu Ijiro
    ChemBioChem 10 230 - 233 2009年01月 [査読有り][通常論文]
  • Hiroshi Yabu, Ruokun Jia, Yasutaka Matsuo, Kuniharu Ijiro, Sada-aki Yamamoto, Fumiaki Nishino, Toshihiko Takaki, Masahiro Kuwahara, Masatsugu Shimomura
    ADVANCED MATERIALS 20 21 4200 - + 2008年11月 [査読無し][通常論文]
     
    Microporous films with various kinds of geometrical patterns including ellipsoids and rectangles are fabricated by using a self-organization process and shrinking. A shrinkable substrate can be used to change the shapes and sizes of honeycomb pores. The pit size can be miniaturized from several micrometers to hundreds of nanometers by repeating the shrinkage.
  • Kenichi Niikura, Shota Sekiguchi, Takashi Nishio, Tomoya Masuda, Hidetaka Akita, Yasutaka Matsuo, Kentaro Kogure, Hideyoshi Harashima, Kuniharu Ijiro
    CHEMBIOCHEM 9 16 2623 - 2627 2008年11月 [査読無し][通常論文]
  • Hiroshi Yabu, Ruokun Jia, Yasutaka Matsuo, Kuniharu Ijiro, Sada-aki Yamamoto, Fumiaki Nishino, Toshihiko Takaki, Masahiro Kuwahara, Masatsugu Shimomura
    ADVANCED MATERIALS 20 21 4200 - + 2008年11月 [査読無し][通常論文]
     
    Microporous films with various kinds of geometrical patterns including ellipsoids and rectangles are fabricated by using a self-organization process and shrinking. A shrinkable substrate can be used to change the shapes and sizes of honeycomb pores. The pit size can be miniaturized from several micrometers to hundreds of nanometers by repeating the shrinkage.
  • Aya Tanaka, Yasutaka Matsuo, Kenichi Niikura, Kuniharu Ijiro
    CHEMISTRY LETTERS 37 7 758 - 759 2008年07月 [査読無し][通常論文]
     
    The effect of 5'-phosphorylation at nicks on DNA stabilization was measured through the formation of DNA multiassemblies consisting of 40-mer half-sliding complementary oligon-cleotides, which had overlapping complementary 20-mer base sequences. 5'-Phosphorylated oligonucleotides formed longer DNA multiassemblies than 5'-hydroxylated ones. This result indicated that the 5'-phosphorylated sticky ends contribute to the stabilization of the DNA association due to the hydrogen bonds between 3'-hydroxy groups and 5'-phosphate groups at the nick positions.
  • Osamu Haruta, Yasutaka Matsuo, Yuichi Hashimoto, Kenichi Niikura, Kuniharu Ijiro
    LANGMUIR 24 6 2618 - 2624 2008年03月 [査読無し][通常論文]
     
    We investigated the molecular recognition between the amphiphile AzoAde, which is composed of azobenzene in the hydrophobic and adenine in the hydrophilic portion of the molecule, and oligonucleotides having a homogeneous base (dA(30), dT(30), dG(30), and dC(30)) at the air-water interface. On the basis of the complementary base-pairing of DNA in the duplex, orderly arrangement of AzoAde on templated dT(30) was examined using pi-A isotherm, UV-vis RAS, FT-IR RAS, and XPS measurements. Although there was little interaction between AzoAde and mismatched oligonucleotides (dA(30), dG(30) and dC(30)), AzoAde prepared on a dT(30) interacted with dT(30), subsequently forming a J-form assembly at the air-water interface. AFM observation of the LB films revealed the nanostructure of the J-formed AzoAde monolayer on the dT(30) subphase as well as the domain structures of the H-formed monolayers on the other oligonucleotide subphases. Therefore, dT(30) has a potential application as a template for assembling AzoAde at the air-water interface.
  • Osamu Haruta, Yasutaka Matsuo, Kuniharu Ijiro
    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 313 595 - 599 2008年02月 [査読有り][通常論文]
     
    UV irradiation-induced fluorescence enhancement of thin films composed of azobenzene amphiphiles, C(12)AzoC(10)N(+) (AzoN(+)), was investigated. UV irradiation to Langmuir-Blodgett (LB) monolayers of AzoN(+) indicated that the fluorescence emission from an irradiated area was enhanced and the emission was independent of the aggregation structures of an azobenzene moiety. Moreover, UV irradiation to cast films of AzoN(+) revealed that the enhancement was increased by increasing the irradiation time. The fluorescence by excitation at 365 nm occurred over a wide range of wavelengths from around 400 nm to 650 nm, and the emission was not attributed to the J-aggregates of AzoN(+). The mechanism for this phenomenon has not been elucidated. It may be caused by the photo-chemical reaction of the azobenzene moiety or photo-induced specific aggregates. However, UV irradiation-induced fluorescence enhancement can be applicable to optical memory devices. (C) 2007 Elsevier B.V. All rights reserved.
  • Hiroshi Yabu, Yuji Hirai, Yasutaka Matsuo, Kuniharu Ijiro, Masatsugit Shimomura
    MACROMOLECULAR SYMPOSIA 267 100 - 104 2008年 [査読無し][通常論文]
     
    We have reported that honeycomb-like porous polymer films, which were spontaneously formed in the casting of polymer solutions under humid conditions, were converted into honeycomb-like metal meshes by electroless plating. In this report, the unique optical properties of these meshes will be discussed. Silver-coated honeycomb mesh films were prepared by self organization and electroless plating methods. The incident angle dependence of their transparency, and their electrical conductivity were measured. The metallized film had limited viewing angle.
  • Aya Tanaka, Yasutaka Matsuo, Yuichi Hashimoto, Kuniharu Ijiro
    CHEMICAL COMMUNICATIONS 36 4270 - 4272 2008年 [査読無し][通常論文]
     
    Platinum metal was sequence-specifically deposited on the DNA block copolymer synthesized by the Klenow fragment of E. coli DNA polymerase I (3'-5' exonuclease deficient).
  • Hiroshi Yabu, Yuji Hirai, Yasutaka Matsuo, Kuniharu Ijiro, Masatsugit Shimomura
    MACROMOLECULAR SYMPOSIA 267 100 - 104 2008年 [査読無し][通常論文]
     
    We have reported that honeycomb-like porous polymer films, which were spontaneously formed in the casting of polymer solutions under humid conditions, were converted into honeycomb-like metal meshes by electroless plating. In this report, the unique optical properties of these meshes will be discussed. Silver-coated honeycomb mesh films were prepared by self organization and electroless plating methods. The incident angle dependence of their transparency, and their electrical conductivity were measured. The metallized film had limited viewing angle.
  • Yasuyuk Tsuboi, Masayuki Nishino, Yasutaka Matsuo, Kuniharu Ijiro, Noboru Kitamura
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 80 10 1926 - 1931 2007年10月 [査読無し][通常論文]
     
    We demonstrate that phase separation of an aqueous poly(vinyl methyl ether) (PVME) solution can be triggered not only by a temperature change but also by photon pressure. A near-infrared continuous wave laser beam (lambda = 1064 nm) was focused through an objective lens into a heavy water (D2O) solution of PVME. A single PVME microparticle was produced and trapped at the focal point of the laser beam within several hundreds of seconds after switching on the laser. The origin of the microparticle formation (phase separation) is ascribed essentially to the photon force of the laser beam, and not to a rise in the local temperature, since heavy water is transparent at 1064 nm. The structures of the PVME microparticles produced by laser irradiation were studied in detail using confocal Raman microspectroscopy. Raman spectra of the microparticles and coiled/globular PVME were observed successfully over a wide wavenumber region. It was confirmed that the phase transition of the polymer chains from coiled to globular states proceeded during microparticle formation. The fundamental mechanism of photo-induced phase separation of PVME is discussed in terms of the interactions between the polymer and the photon force.
  • Kenichi Niikura, Takashi Nishio, Hidetaka Akita, Yasutaka Matsuo, Ryosuke Kamitani, Kentaro Kogure, Hideyoshi Harashima, Kuniharu Ijiro
    CHEMBIOCHEM 8 4 379 - 384 2007年03月 [査読無し][通常論文]
  • Noriko Ishizuka, Yuichi Hashimoto, Yasutaka Matsuo, Kuniharu Ijiro
    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 284 440 - 443 2006年08月 [査読無し][通常論文]
     
    Deoxyribonucleic acid (DNA) has a lot of characteristic features, e.g., anionic polyelectrolyte, molecular recognition and condensed pi electron. Therefore, it is expected to be applied as functional materials in not only biological but also physical fields. In this report, we attempted to prepare water-insoluble DNA films by mixing DNA and photolinkable polymer, aiming at the fabrication of bio-functionalized hydrogel films. For this purpose, photocrosslinkable polyvinyl alcohol (azide-unit pendant water-soluble photopolymer; AWP) was used. An aqueous DNA and AWP mixture was cast onto glass substrates. Irradiation of UV light on it for certain minutes provided a hydrogel film by photocrosslinking between DNA and AWP. When the formed hydrogel film was soaked in pure water for I day, large expansion of the film was observed. The expanded film was shrunk by soaking it in aqueous NaCl or CTAB solutions. The expansion and shrinkage mechanism of the film was attributed to the penetration of water into the gap between the film and the substrate due to osmotic pressure. This phenomenon can be applied to the fabrication of gel devices, e.g., a novel biosensor and drug delivery system. (c) 2005 Elsevier B.V. All rights reserved.
  • Aya Tanaka, Yasutaka Matsuo, Kuniharu Ijiro
    Colloids and Surfaces A 284 246 - 249 2006年08月 [査読無し][通常論文]
     
    We synthesized poly(dG)-poly(dC) by the enzymatic extension of dG(10)-dC(10) with Klenow fragment exo(-). The length of prepared poly(dG)-poly(dC) was determined by the electrophoresis and the Langmuir-Blodgett (LB) method. Cationic amphiphile (2C(18)N(+)2C(1)) was spread on an aqueous solution of synthesized poly(dG)-poly(dC). And a formed polyion complex monolayer at the air-water interface due to the electrostatic interaction between the amphiphile and poly(dG)-poly(dC) was transferred on a glass substrate. The fluorescence images of the transferred polyion complex monolayers showed that single poly(dG)-poly(dC) molecules were stretched on the glass substrate and the lengths of the stretched molecules almost corresponded to 21,000 bp. The stretched poly (dG)-poly(dC) can be used as a sample for electric conductivity measurement and a template for spatially arranging molecules and metals. (c) 2005 Elsevier B.V. All rights reserved.
  • IJIRO Kuniharu, MATSUO Yasutaka, HASHIMOTO Yuichi
    Mol Cryst Liq Cryst 445 497-501  2006年 [査読無し][通常論文]
  • Yasutaka Matsuo, Kuniharu Ijiro
    INTERNATIONAL JOURNAL OF NANOSCIENCE, VOL 5, NO 6 5 6 697 - + 2006年 [査読無し][通常論文]
     
    In this report, the stripe pattern formation of oligonucleotide in Langmuir-Blodgett (LB) monolayer was investigated. A polyion complex monolayer of oligonucleotide and cationic amphiphile spread on a TE buffer solution of a RhodamineX-labeled oligonucleotide was transferred on a glass substrate by the LB method. Fluorescence images of the transferred polyion complex monolayers showed that stripe patterns of the oligonucleotide were formed. The interval of the lines was dependent on the transferring speed of the substrate.
  • K Ijiro, Y Matsuo, Y Hashimoto
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS 445 207 - 211 2006年 [査読有り][通常論文]
     
    The precise metallization of double-stranded DNA by the selective electroless plating method was investigated for the purpose of the fabrication of nanowires. Cis-platin was bound to template DNA molecules and reduced to platinum which can catalyze following silver metal deposition. The DNA molecules combined with the platinum clusters was stretched and immobilized on a glass substrate by using the LB method. The electroless plating of the platinum-bound DNA molecules immobilized on the substrate by reduction of silver ion gave uniform silver nanowires (ca. 30 nm height and 50 similar to 100 nm width) along the stretched DNA structures. On the contrary, the electroless plating of DNA molecules without the catalyst provided inhomogeneous silver deposition. Conductive AFM measurement revealed that the obtained silver nanowires as long as several mu m had high conductivities.
  • HASHIMOTO Yuichi, MATSUO Yasutaka, IJIRO Kuniharu, IJIRO Kuniharu
    Trans Mater Res Soc Jpn 30 3 671-674  2005年09月 [査読無し][通常論文]
  • Kuniharu Ijiro, Yasutaka Matsuo, Yuichi Hashimoto
    e-Journal of Surface Science and Nanotechnology 3 82 - 85 2005年03月03日 [査読無し][通常論文]
     
    For the purpose of the fabrication of nanowires, the metallization of double-stranded DNA by the selective electroless plating method was investigated. Cis-platin was bound to template DNA molecules and reduced to platinum which can catalyze subsequent silver metal deposition. We have found that when DNA-amphiphile polyion complex monolayer, which was formed at the air-water interface, was transferred to a glass substrate by using the Langmuir-Blodgett (LB) method, DNA molecules could be immobilized and stretched on the glass substrate. The DNA molecules combined with the platinum clusters was also stretched and immobilized on a glass substrate by using the LB method. The electroless plating of the platinum-bound DNA molecules immobilized on the substrate by reduction of silver ion gave uniform silver nanowires (c.a. 50nm in width and height) along the stretched DNA structures. On the contrary, the electroless plating of DNA molecules without the catalyst provided inhomogeneous silver deposition. © 2005 The Surface Science Society of Japan.
  • Y Matsuo, K Ijiro, M Shimomura
    COLLOIDS AND SURFACES B-BIOINTERFACES 40 3-4 123 - 126 2005年02月 [査読無し][通常論文]
     
    We have proposed a new technique for stretching single double-stranded DNA molecules on solid substrates by the Langmuir-Blodgett (LB) method. The polyion complex monolayer of a cationic amphiphile and DNA molecules formed at the air-water interface was transferred on a clean glass substrate. Vertical lifting up of the glass substrate provided the transferred monolayer consisting the stretched individual DNA molecules aligned parallel to the lifting direction on the glass. The DNA molecules complexed with the restriction endonuclease (EcoRI) were employed for stretching by using this method. Fluorescence images of the transferred monolayer showed that the EcoRI-binding DNA molecules could be stretched and immobilized on the glass substrate. A specific sequence of DNA recognized by EcoRI was detected as spatial positions of the stretched DNA molecules. (c) 2004 Elsevier B.V. All rights reserved.
  • Y Hashimoto, Y Matsuo, K Ijiro
    CHEMISTRY LETTERS 34 1 112 - 113 2005年01月 [査読有り][通常論文]
     
    Precise and uniform metallization of double-stranded DNA by the selective electroless plating method was investigated for the fabrication of nanowires. Cis-platin was bound to template DNA molecules and reduced to platinum which then catalyzed silver metal deposition. The DNA molecules combined with the platinum clusters were stretched and immobilized on a glass substrate using the Langmuir-Blodgett (LB) method. The electroless plating of the platinum-bound DNA molecules by the reduction of silver ions yielded uniform silver nanowires (ca. 50nm in width and height) along the stretched DNA molecules. Conductive AFM measurements revealed that a high electric conductivity over a length of 6mum from the edge of a micro electrode.
  • Monma F, Tsuruma A, Matsuo Y, Hotta J.-I, Tanaka M, Yamamoto S, Sasaki K, Ijiro K, Nakamura H, Shimomura M
    Polymer Preprints, Japan 54 1 2233  2005年 [査読有り][通常論文]
  • Yamamoto S, Sunami H, Tanaka M, Matsuo Y, Ijiro K, Yamashita S, Morita Y, Shimomura M
    Polymer Preprints, Japan 54 1 887  2005年 [査読有り][通常論文]
  • Y Matsuo, K Ijiro, M Shimomura
    ASIANANO 2002, PROCEEDINGS 321 - 325 2003年 [査読有り][通常論文]
     
    We propose a new method that double-stranded DNA molecules can be stretched and immobilized on the clean glass substrate by using a lipid monolayer at the air-water interface. This method is based on the substrate lifting of Langmuir-Blodgett method. We observed fluorescence images of polyion complex films with a scanning near-field optical microscope (SNOM). As a result, straight fluorescent lines aligned parallel to the lifting direction were observed and it was considered that isolated single DNA molecules were extended to align on the substrate. This method is applied to various DNA molecules.
  • Matsuo Yasutaka, Sasaki Keiji
    Japanese Journal of Applied Physics 40 Part 1, No. 10 6143 - 6147 公益社団法人 応用物理学会 2001年10月15日 
    A new technique is proposed for the transient absorption spectroscopy of a single metallic nanoparticle. This technique is based on a differential interference contrast (DIC) microscopy using pulsed laser light. A single nanoparticle is excited by a pumping laser beam, and the DIC signal of a probing light is measured to precisely determine the amplitude and phase of the forward-scattered light. The refractive index and the absorption coefficient of the excited particle can be estimated on the basis of the Rayleigh scattering theory. By changing the delay time between the pumping and probing pulses, absorption dynamics of a single nanoparticle can be observed on a femtosecond time scale. As a preliminary experiment, the electron dynamics of a 70 nm silver colloidal particle was analyzed with this technique.
  • Yasutaka Matsuo, Hidehisa Takasaki, Jun-ichi Hotta, Keiji Sasaki
    Journal of Applied Physics 89 10 5438 - 5441 2001年05月15日 [査読有り]
  • Tsuyoshi Asahi, Yasutaka Matsuo, Hiroshi Masuhara, Hideko Koshima
    The Journal of Physical Chemistry A 101 4 612 - 616 1997年01月 [査読有り]
  • Tsuyoshi Asahi, Yasutaka Matsuo, Hiroshi Masuhara
    Chemical Physics Letters 256 4-5 525 - 530 1996年07月 [査読有り]

書籍

  • ナノバイオ大事典 -COMPREHENSIVE NANO-BIO HANDBOOK-
    ㈱テクノシステム 2007年

その他活動・業績

特許

  • 炭素構造体の製造方法及び炭素構造体、並びに炭素構造体の集合体及び分散体
    2007-169148
  • 生体適合性および高体積変化能を有する組織体ならびにその作製方法
    2006-204813
  • DNAを用いた透明電極の作製方法
    2006-207010
  • DNA一分子の特異的塩基配列検出法
    2004-283098
  • 環状DNAの伸長固定化法
    2004-147537

共同研究・競争的資金等の研究課題

  • ナノ微細構造と光励起を利用した汎用超高感度ソフトイオン化法の開発
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2021年04月 -2024年03月 
    代表者 : 大須賀 潤一, 松尾 保孝, 古谷 浩志, 豊田 岐聡
  • ナノ構造を用いた光増強ソフトイオン化法による大気中有機ナノ粒子の直接質量分析
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2019年04月 -2022年03月 
    代表者 : 松尾 保孝, 大須賀 潤一, 古谷 浩志
     
    本研究では、微量な試料となる大気中ナノ粒子の有機物の“直接”質量分析を行うために必要となる、ナノ粒子を直接捕集し、かつ有機物をフラグメント化させずにレーザー脱離・イオン化(ソフトイオン化)する高効率なイオン化分析チップの開発を行う。具体的には、シリコン三次元ピラー構造表面に数十nmのポーラス構造と、貴金属ナノ粒子に生じる局在表面プラズモンの光アンテナ効果による電場増強を組み合わせた新規なソフトイオン化基板を開発し、大気中ナノ粒子における低分子有機物の高効率質量分析を行う。また、大気中ナノ粒子を捕集する多段インパクター(Micro Orifice Uniform Deposition Impactor:MOUDI)に作製した分析チップを取り付けることで、ナノ粒子捕集から質量分析までをワンチップ上で行えるシステムを構築し、大気中ナノ粒子の迅速分析の実現を目指す。 今年度は、n型シリコン基板上にフォトレジストで直径数ミクロン程度の円形パターンを作製し、ドライエッチング装置にて高さ数ミクロンの円柱形状を作製した。また、目的とする円錐構造を作成するために、ドライエッチングの出力、ガス流量、経時的な出力とガス流量の変動による形状制御性について検討し、必要となるテーパー角度制御性についての検討を行った。その結果、円錐形状作製のためにはレジスト膜厚およびレジスト形状についても加工を行う必要があることが分かった。また、作製した円柱を持つ基板をフッ酸/エタノールの混合溶媒中にて電解を行い、円柱構造を含めて基板表面全体に数10nm~100nm程度のナノポーラスを形成した三次元ナノポーラスシリコン基板を作製することに成功した。 また、本形状チップへレーザー照射しても構造が破損しないことや多段式インパクターへ取り付け可能なサイズであることを検証した。
  • 近距離Casimir力の起源となる表面プラズモン振動モードのEELS解析と力評価
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2018年04月 -2021年03月 
    代表者 : 坂口 紀史, 國貞 雄治, 松尾 保孝
     
    本年度も引き続き金属平板間における表面プラズモン共鳴(SPR)の相互作用に関する評価を実施した。金属としてAgを選定し、前年度と同様の方法を用いてSi基板上にAg/SiO2/Ag膜ならびにAg/Al2O3/Ag膜を成膜し、FIBにて断面サンプルを作製することで、これを平行金属板とみなした。SiO2およびAl2O3層の厚みを変えたサンプルを複数作製し、平板間距離とSPR相互作用の関係をSTEM-EELSにより実測した。くわえて、Ag膜間にSiO2とAl2O3膜を同時に挟んだAg/SiO2/Al2O3/Ag膜も成膜した。すべてのサンプルにおいて、単一Ag平板/誘電体界面に励起されるSPR共鳴エネルギーよりも高エネルギー側に共鳴ピークが現れることが分かった。Al2O3とSiO2を挟んだサンプルを比較した場合、より屈折率の大きなAg/Al2O3/Ag膜においてSPR共鳴エネルギーは低下した。また、どちらにサンプルについても平板間距離が狭くなるほどそのエネルギーは上昇することが明らかとなった。離散双極子近似(DDA)を用いたシミュレーションからも同様の結果を得た。一方、異なる誘電体を並べたAg/SiO2/Al2O3/Ag膜について、SPR共鳴エネルギーはAg/SiO2単一界面あるいはAg/Al2O3/Agギャップにおけるエネルギーに近い値を示した。二つの界面におけるSPPの分散関係は異なることより、その相互作用は複雑であることが示唆される。
  • 日本学術振興会:科学研究費助成事業 基盤研究(A)
    研究期間 : 2017年04月 -2020年03月 
    代表者 : 藪 浩, 西浦 廉政, 加藤 竜司, 中嶋 健, 松尾 保孝
     
    弾性率制御されたハニカムスキャフォールドの作製法を確立し、ヒト間葉系幹細胞(hMSC)やiPS細胞などの幹細胞および神経系細胞などについてその接着・増殖・分化をモニタリングすることに成功した。これらのデータベースを基に特徴的な分化制御能を与える材料変面条件を得ることに成功した。また、Coupled Cahn-Hilliard方程式を基にした高分子微粒子構造制御の理論モデル構築に成功し、本モデルを基に自己組織化による有機無機コンポジット微粒子の作製に成功した。磁性粒子と金ナノ粒子をコンポジットした高分子微粒子は液中で磁場によって任意の部位のラマン散乱測定が可能であることを明らかとした。
  • 日本学術振興会:科学研究費助成事業 挑戦的萌芽研究
    研究期間 : 2016年04月 -2018年03月 
    代表者 : 藪 浩, 松尾 保孝
     
    可逆的付加-開裂連鎖移動(RAFT)重合を用いて、ポリビニルカテコール(PVCa)をブロックとして持つジブロックおよびトリブロック共重合体の合成に初めて成功した。ジブロック共重合体をテンプレートに磁性ナノ粒子と銀ナノ粒子を段階的に導入・還元することにより配列させる事に成功した。本フィルムはプラズモン吸収波長において特徴的な磁気光学特性を示した。 以上の結果から、バイオミメティックブロック共重合体を用いることで、新たなメタマテリアル作製手法が得られることを実証した。
  • 日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2012年06月 -2017年03月 
    代表者 : 下村 政嗣, 長谷山 美紀, 石田 秀輝, 針山 孝彦, 森 直樹, 劉 浩, 大園 拓哉, 穂積 篤, 細田 奈麻絵, 齋藤 正男, 野村 周平, 松尾 保孝, 居城 邦治
     
    進化適応の結果である生物多様性を、持続可能性をもたらす“壮大なるコンビナトリアル・ケミストリー”と位置つけることで、自然史学、生物学、農学、材料科学、機械工学、情報学、環境政策学、社会学等の研究者による我が国では類を見ない異分野連携研究ネットワークを構築することにより、ニーズ・シーズ・マッチングと発想支援が可能となる「バイオミメティクス・データベース」を編纂し、情報科学による生物から工学への技術移転が可能であることを実証した。
  • 日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2012年06月 -2017年03月 
    代表者 : 細田 奈麻絵, 前田 浩孝, 穂積 篤, 浦田 千尋, 重藤 暁津, 松尾 保孝, 和田 健彦, 北島 博, 居城 邦治
     
    生物のサブセルラー・サイズ構造の階層性は、防汚(ナメクジや蓮の葉)、自己治癒(葉の表面)、可逆的接着性(昆虫の脚裏)など多様な機能を発現している。本研究では、生物物理・材料/表面科学の視点からそのしくみを解明し、革新的な材料開発を目指した。中間評価以降は、特にエレクトロニクス実装への応用が可能な基盤技術(可逆的接合、セルフアライメント技術、防汚/防錆性付与、自己治癒による長寿命化、放熱特性の向上など)を重点項目として位置付け研究を展開した。これにより、人工材料にない優れた多層膜皮膜の開発、全く新しい発想による泡を利用したセルフアライメント、可逆的な接着機構の実現などほぼ計画通り達成できた。
  • 日本学術振興会:科学研究費助成事業 挑戦的萌芽研究
    研究期間 : 2013年04月 -2015年03月 
    代表者 : 松尾 保孝
     
    本研究は窒化物、特にチタン窒化物のナノ構造を電子線リソグラフィーを利用した微細加工技術によって作製し、新しい可視光域のプラズモニックデバイスの創製を行うことであった。 成果として、イオンビーム(Arイオン)を照射するスパッタ装置において、窒素ガス雰囲気かでチタン成膜を行うことにより、窒素含有のチタン薄膜の作製が可能となった。また、電子ビームリソグラフィーによりナノパターンを形成したところに成膜を行うことでチタン窒化物のナノ構造が作製できることを確認した。また、このチタン窒化物上で有機分子のラマン散乱測定が可能であることを示した。
  • MENDで拓く遺伝子治療への道:遺伝子の運び屋からナノマシンへ
    日本学術振興会:科学研究費助成事業 基盤研究(S)
    研究期間 : 2010年05月 -2014年03月 
    代表者 : 原島 秀吉, 山田 勇磨, 中村 孝司, 兵藤 守, 馬場 嘉信, 篠原 康雄, 小暮 健太朗, 紙谷 浩之, 渡慶次 学, 松尾 保孝, 秋田 英万
     
    パッチワーク法による新しいMEND構築方法を確立し一枚膜でコア粒子をパッケージする新しい方法を開発し、平均粒子径が25nm程度でゼータ電位が-40mV程度の構造体を得ることに成功し、P-MENDと命名した。D-MEND法と組み合わせることでPD- MEND(3枚膜構造)を構築したところ、市販の試薬より高い活性を示した。マイクロ流体デバイスを開発し、最小粒径30nmのMENDを作製することに成功した。一方でマイクロ流路作製についての検討し、ナノインプリント手法によりガラスマイクロ流路の量産が可能であることをしめした。また、シースフローと電場を利用したマイクロフリーフロー電気泳動デバイスの構造・分離条件の最適化を行い、MEND精製に適用することでMENDの定性的かつ定量的評価法を確立した。KALAペプチドを導入した脂質膜封入型ナノ粒子にがん抗原等をコードした遺伝子を封入することで、抗腫瘍活性を得ることに成功した。また、本粒子は細胞に対し免疫活性化効果を有することを示し、その機構に細胞質内DNAセンサーが関与することを示唆する結果を得た。酵素耐性RNAアプタマーの単離に世界で始めて成功した。Mt移行性ペプチドを搭載したMTS-MITO-Porterを構築し、生細胞内での選択的Mt送達システムを開発し、MTS-MITO-Porterは従来型MITO-Porterと比較してミトコンドリア移行能が飛躍的に上昇した。GAL4とVP16の融合蛋白質を用いる自己活性化システムを構築し、reporterプラスミドDNAの単独投与に比べて数十倍にルシフェラーゼ活性が上昇した。アンチセンスRNA (ASO)をMITO-Porterを用いて細胞Mtに送達し、ミトコンドリアmRNAを40%抑制し、さらに標的mRNAがコードする内因性Mtタンパク質の発現量が低下した。
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2011年 -2013年 
    代表者 : 三谷 篤史, 松尾 保孝
     
    10~100μmサイズの微小物体の振動輸送において,トライボロジ特性を考慮した微小物体の動特性を解明することを目的とする.これまでに,微小物体を輸送するために,非対称形状に加工したフィーダ表面を有するマイクロパーツフィーダを提案している.本研究では,面方位<221>結晶面を表面とするシリコンウェハの異方性エッチング加工により得られる非対称形状表面を開発した.微小物体の輸送実験を通してその適用可能性を検討すると共に,動き解析マイクロスコープを用いた微小物体の運動解析を通して輸送の安定性を検証した.
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2010年 -2012年 
    代表者 : 居城 邦治, 佐野 健一, 新倉 謙一, 松尾 保孝, 島本 直伸, 三友 秀之
     
    単電子トランジスタは、劇的な低消費電力を可能とする素子として注目されている。室温での動作を可能にするためには、ソース電極とドレイン電極の間に直径は数nmの「クーロン島」(極小の導電性金属)をnmの精度で置く必要がある。しかしながら現在のフォトリソグラフィー技術ではこのような精密な構造を作ることは不可能である。そこで本研究では核酸DNAの分子認識を用いることで、自己組織化的にナノワイヤー-量子ドット-ナノワイヤー構造のような単電子トランジスタ構造を作製した。
  • 文部科学省:科学研究費補助金(若手研究(B))
    研究期間 : 2011年 -2011年 
    代表者 : 松尾 保孝
     
    本研究は、発光する金属クラスターを作製し、表面プラズモンを有する金属ナノ粒子上に集積させることで発光効率を向上させた階層構造を持つ新しい発光する金属ナノ粒子を作製することとである。特にDNAを用いた作製方法により生体親和性の高い光る金属ナノ粒子を試みた。その結果、核酸塩基の種類により発光の特徴が変わることがわかり、長時間安定な金属クラスター作製に成功した。この結果、様々な応用が可能であることがわかった。
  • 文部科学省:科学研究費補助金(基盤研究(A))
    研究期間 : 2006年 -2009年 
    代表者 : 笹木 敬司, 松尾 保孝, 藤原 英樹, 松尾 保孝
     
    本研究では、放射圧を利用して光子の状態を保ったまま光子を検出するという全く新しいアイデアに基づく光物理計測手法を開発することを目的として、a)光子1個レベルを検出するために光子場を増強する手法の考案、b)極めて高感度な力測定技術の開発および熱雑音の抑制技術の確立を行った。開発したシステムを用いれば、光子を消滅させず何度でも検出することができるので、光子の時間・空間などマルチパラメータの計測が可能となる。具体的には、微小共振器のQ値に対応して得られる光増強度の見積りを行った。その結果得られる変位量や実験装置の位置検出感度等の試作に必要な実験条件の見積りを行った。これらの結果をもとにファイブリー・ペロー共振器を元にしたシステムの設計を行った。また、金コートしたAFMプローブに周波数変調したレーザー光を入射しながら、AFMプローブの変位を測定した。その結果、熱による形状変化とは別に放射圧による変調成分を高感度に観測することに成功した。これらの知見をもとに金コートAFM プローブを片側ミラーとしたファブリ・ペロー共振器を含むシステムの試作を行った。さらに、テーパーファイバを作製するための装置の設計、構築を行い、最適なテーパー形状を得る為の作製パラメータの探索を行った。その結果、安定して1μm程度のテーパー径をもつテーパーファイバの作製が可能となった。また、このテーパーファイバと微小球...
  • 文部科学省:科学研究費補助金(特定領域研究)
    研究期間 : 2008年 -2008年 
    代表者 : 松尾 保孝
     
    金属ナノ構造体に局在化した光電場と蛍光分子が強くカップリングし、蛍光強度が大幅に増強される現象が報告されている。我々がDNAを鋳型とした銀ナノ粒子の作製を行ったところ、核酸塩基の種類によって作製される銀ナノ粒子のサイズが異なることや作製した銀ナノ粒子が光励起によって可視域に強い発光を示すことを見いだした。通常、DNAは可視域において発光しないことから銀ナノ粒子とDNA間の相互作用が発光に重要な役割を果たしていると考えられる。本研究では銀ナノ粒子の作製条件を調整してDNAと結合した銀ナノ粒子の構造制御を試みることやその発光特性についての分析を行うことにより、発光メカニズムの詳細について検討を行った。DNAが結合した銀ナノ粒子は単一塩基で構成される一本鎖DNA (オリゴヌクレオチド) を含む緩衝溶液へ硝酸銀水溶液を加えた混合溶液に紫外光を約5分間照射することにより作製した。吸収スペクトルが銀ナノ粒子の表面プラズモン吸収に由来するピークを示すことや透過電子顕微鏡 (TEM) 像から、粒径が10nm〜50nm程度の銀ナノ粒子の形成を確認した。蛍光相関分光法による測定から発光ナノ粒子のサイズが約10nmであることがわかり、TEM像の結果と併せることにより単一銀ナノ粒子が発光していることが示唆された。また、銀ナノ粒子を基板上に固定化して励起光を照射すると発光が観察されるが、照射時間が一時...
  • 文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2007年 -2008年 
    代表者 : 居城 邦治, 新倉 謙一, 松尾 保孝
     
    高度情報通信社会を将来にわたって持続的に発展させるためには、電子デバイスの微細化と高性能化を低コストでさらに進めなければならないが、これは従来の半導体デバイスの延長線上では実現が困難であり、それに代わる新しいナノデバイスの開発が不可欠である。そこで本研究では単一分子で動作する極微細ナノデバイスの作製を目標として、DNAの自己組織化と無電解メッキを応用することで単一分子デバイスを作製する手法の開発を行った。
  • 文部科学省:科学研究費補助金(萌芽研究)
    研究期間 : 2007年 -2008年 
    代表者 : 新倉 謙一, 澤 洋文, 松尾 保孝, 居城 邦治
     
    ウイルスのタンパク質が自己集合して形成するウイルス様微粒子(virus-like particle : VLP)は、ウイルスゲノムを持たずにウイルスと同じ経路で細胞内へ導入されるため、ドラッグデリバリーシステムのキャリアー等として注目されている。私たちはVLPの持つ糖鎖認識性に着目し、糖鎖の分子認識を利用してウイルスの周辺に規則的に金属微粒子を配列させることを目的に研究を進めた。まず金微粒子にシアル酸を提示させる技術を確立した。このシアル酸提示金微粒子は非常に水への分散性が高く、ウイルスと結合させても沈殿するようなことはなかった。VLPとシアル酸を修飾した金ナノ粒子の複合体形成の電子顕微鏡像(STEM)を詳細に検討すると、VLPの表層に特異的に金ナノ粒子が結合している様子が観察された。また、紫外可視吸収スペクトルの長波長シフトには、金ナノ粒子表面のシアル酸の有無によって有意な差が生じたことから、溶液中でも金ナノ粒子がVLPに結合していることが示された。さらに金ナノ粒子濃度の上昇に伴いプラズモン吸収の長波長側への大きなシフトが測定された。これはウイルスを鋳型とした金ナノ粒子の結合により、三次元的なプラズモンのカップリングが起きたことを意味している。さらにウイルスと金微粒子の結合を促進するために、デキストランを添加した。この効果は高分子クラウディング効果と言われるが、金属微粒子と...
  • 文部科学省:科学研究費補助金(若手研究(B))
    研究期間 : 2007年 -2008年 
    代表者 : 松尾 保孝
     
    微細な凹凸構造をもつ基板上にDNA を伸長固定化することでDNA 結合タンパク質が自由な環境下でDNA と相互作用が可能となるDNA チップの作製を試みた。研究成果としては光リソグラフィー技術を用いたシリコン基板上への微小な凹凸構造作製、また高分子フィルム上への凹凸構造を作製することにより、様々な基板へのDNA の伸長固定化条件の抽出を行った。これによりDNAとDNA結合タンパク質の相互作用解析用基板の作製を可能にした。
  • 文部科学省:科学研究費補助金(基盤研究(A))
    研究期間 : 2006年 -2008年 
    代表者 : 下村 政嗣, 居城 邦治, 藪 浩, 松尾 保考
     
    本研究では、ボトムアップナノテクノロジ-のキ-技術である自己組織化によるナノ・ミクロ構造形成と、成熟した技術である無電解メッキを組み合わせることで、全湿式プロセスによるラピッドプロトタイピングが可能であることを示すことができた。また、マイクロメ-タ-スケ-ルの細孔を有するハニカム様多孔質フィルムが赤外領域でフォトニック結晶になりうることを確認しており、細孔径のサブミクロン化によって可視光領域でのフォトニック結晶が可能となる。金属化により、高屈折率化と力学強度にすぐれた材料が期待される。
  • 文部科学省:科学研究費補助金(特定領域研究)
    研究期間 : 2005年 -2006年 
    代表者 : 居城 邦治, 新倉 謙一, 松尾 保孝
     
    これまで申請者は、DNA水溶液上にカチオン性の両親媒性化合物を展開し、静電的相互作用により気水界面に形成したDNA分子とのポリイオン複合膜をLangmuir-Blodgett(LB)法により、単分子膜に流動性を持たせた状態で固体基板上に移し取ると、溶液中ではランダムコイル形状であったDNA分子が伸長して固定化されることを見い出してきた。伸長・固定化された個々DNAA分子は長さ解析の結果、単一分子であることが明らかとなり、また二重らせんDNA鎖をほぼ伸び切り構造で2次元に配列することができることを示した。しかし、DNAが伸長するメカニズムは明らかになっていない。そこで研究では、これまで未開拓であったメニスカスにおける高分子鎖のダイナミクスの計測技術の開発を通じて、LB法によるDNAの伸長機構を明らかにすることを目的とした。DNAが気体・液体・固体の三相が交差するメニスカスにおいて伸長されることから、メニスカスでのDNA分子の運動を観察できる蛍光顕微鏡システムを構築した。このシステムを用いてDNA水溶液上にジアルキルアンモニウム塩(2C_<18>N^+2C_1)を展開することで気液界面に形成した2C_<18>N^+2C_1/DNAポリイオン複合単分子膜の観察を行った。その結果、糸まり状のDNAがメニスカス境界部分で数秒間滞留し、その後基板状に伸長した状態で固定化されていく様子が観...
  • 文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2004年 -2005年 
    代表者 : 居城 邦治, 下村 政嗣, 田中 賢, 新倉 謙一, 松尾 保孝, 藪 浩
     
    DNAマイクロアレイは遺伝子解析にとって大変重要な基盤技術である。多量解析のためにはDNAアレイの高度集積化が急務であるが、DNAスポットの間隔を20μm以下にすることは現在の光リソグラフィーによる合成型やスポッターを用いた貼り付け型の技術では困難である。従来のトップダウン法によるDNAマイクロアレイ作製技術に代わり、DNAの塩基対形成による分子認識による100nm間隔のDNA配列技術の開発を目指す。具体的には遺伝子の検出方法として知られているFISH法(Fluorescence In-Situ Hybridization)を使うことで伸長固定化した単一DNA分子でプローブDNAのナノアレイ化を行い、さらにそれらナノアレイを並べて階層化することで高度集積化を図り、従来の1000分の1の大きさのDNAチップの作製を目標とする。特定の間隔のDNA配列技術の開発のモデル実験として、40塩基の20塩基ずつが相補的な2種類の40塩基オリゴマーからなるHalf-sliding DNAの多重会合体形成について検討した。AFMによる観察と環状DNA以外のDNAを加水分解するexonucleaseVによる酵素反応の結果から、TE中で形成されたDNA多重会合体は直鎖状構造であるのに対し、金属イオン下で形成されたものは環状構造であることがわかった。直鎖状のDNA多重会合体は剛直なロッド構造のため多...
  • 新規非線形光学応答素子を目指した伸長・配向制御高分子薄膜の作製と光学特性評価
    日本学術振興会:科学研究費助成事業 特別研究員奨励費
    研究期間 : 2004年 -2004年 
    代表者 : 松尾 保孝
     
    本研究は、有機材料の分子配向と非線形感受率が密接な関係にあることに着目し、高分子配向制御薄膜による新規非線形光学素子の開発を目指して行われた。有機材料は比較的大きな非線形感受率と高速応答を示すことから注目を浴びているが、材料として応用範囲の広い高分子に関しては分子量が大きく、結晶化や化学的な手法で配向制御が困難なために分子配向と非線形光学応答を結びつける研究例は少ない。そこで高分子鎖を配向させる方法としてLangmuir-Blodgett(LB)法を用い、単一高分子鎖レベルで配向制御した高分子薄膜の作製を試みた。 高分子としては有機発光材料として用いられているポリフェニレンビニレンの前駆体(Pre-PPV)を用いた。Pre-PPVをLB法の下水相としてガラス上へ累積を行った。その結果、ガラス基板上に効率よくPry-PPVが累積されることを確認した。しかしながら固定化されたPre-PPV分子からは偏光発光などが観察されなかった。そこでLB法でDNAが伸長・固定化されること、DNAのアニオン性とカチオン性Pre-PPVのポリイオン複合体形成を利用し、LB法によるDNA/Pre-PPV複合体の伸長・固定化を行った。その結果、DNAに沿ってPre-PPVが基板上に固定化されることがわかった。また、溶液中の蛍光スペクトルからDNA/Pre-PPVの複合体形成によりPre-PPVのコンフォメーション変化が誘起されることがわかった。このことからDNAを鋳型とすることで非線形光学材料の分子配向制御・固定化が可能であることが示された。
  • 文部科学省:科学研究費補助金(基盤研究(A))
    研究期間 : 2002年 -2004年 
    代表者 : 下村 政嗣, 澤田石 哲郎, 田中 賢, 居城 邦治, 山本 貞明, 松尾 保孝, 藪 浩
     
    本研究の目的は、高分子溶液をキャストした際に結露した水滴を鋳型として生成されるハニカム構造化膜の空孔中に発光性の微粒子を封入し、面状に発光するデバイスを作製することである。今年度は色素を分散させた微粒子作製と、そのハニカム膜への導入を行った。色素とポリスチレンを溶かしたテトラヒドロフラン(THF)溶液に貧溶媒である水を加え、THFを蒸発させてやると、300nm前後の色素を担持したポリスチレン微粒子が形成されることを見出した。ハニカム膜は疎水的な材料から作製されているため、その表面は高い撥水性を示す。従って微粒子の水分散液を導入しようとすると全く濡れることが出来ない。ここでハニカム膜の表面を親水化するために、UV-オゾン処理を行う方法を考案した。UV-オゾン処理により表面が親水化され、ハニカム状の空孔に微粒子が導入されやすい状態となった。空孔中に微粒子を導入する方法はキャスト法やディップコート法などの方法が考えられるが、これらの方法では連続処理に向かなかったり、粒子を十分導入できない等の問題がある。そこで微粒子分散液を2枚のスライドガラスでははさみ、一方のスライドガラスに親水化したハニカム膜を固定し、一方のスライドガラスを一定速度でスライドさせる方法を考案した。その結果、非常に効率よく、よりパッキングしたハニカム-微粒子ハイブリッド構造が家試製された。色素を励起すると孔部分が明...

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