研究者業績

住友 弘二

スミトモ コウジ  (Koji Sumitomo)

基本情報

所属
兵庫県立大学 材料・放射光工学専攻 教授
学位
工学博士(大阪大学)

研究者番号
30393747
J-GLOBAL ID
201801011551699790
researchmap会員ID
B000299915

研究詳細と最新の業績リストは下記サイトをご覧ください
http://www.eng.u-hyogo.ac.jp/faculty/sumitomo/index.html

研究キーワード

 2

経歴

 2

学歴

 2

論文

 146
  • Koji Sumitomo, Hiroto Yoshimizu, Azusa Oshima, Masumi Yamaguchi, Akira Heya
    Japanese Journal of Applied Physics 63 09SP24 2024年9月2日  査読有り筆頭著者
  • Naoto MATSUO, Akira HEYA, Kazushige YAMANA, Koji SUMITOMO, Tetsuo TABEI
    IEICE Transactions on Electronics E107.C(3) 76-79 2024年3月1日  査読有り
  • Akira Heya, Akinori Fujibuchi, Masahiro Hirata, Yoshiaki Matsuo, Junichi Inamoto, Kazuhiro Kanda, Koji Sumitomo
    Japanese Journal of Applied Physics 63 02SP20 2024年2月29日  査読有り
  • Kanta Yamamoto, Yuichi Utsumi, Ikuya Sakurai, Ikuo Okada, Kenji Hanada, Hidehiro Ishizawa, Masahiro Takeo, Taki Watanabe, Sho Amano, Satoru Suzuki, Koji Sumitomo, Akinobu Yamaguchi
    Journal of Vacuum Science & Technology B 41(6) 2023年10月11日  査読有り
    We have completed a system that can achieve both deep x-ray lithography and submicron x-ray lithography with a single beamline by introducing the combination of x-ray plane and cylindrical mirrors. This x-ray lithography system can provide a large-scale microfabrication processing with 210 × 300 mm2 (A4 size). To exploit multiscale lithography, the beamline has a beam transport vacuum duct with a two-stage stacked structure and a 5-axis stage. This two-stage stacked structure allows us to fabricate both micron scale structures with high aspect ratios and submicron scale structures using the same beamline. In addition, x-ray imaging and computer tomography (CT) system are connected to the x-ray lithography system for nondestructive inspection and evaluation of the fabricated microstructures. The x-ray imaging system constructed this study has a relatively low energy range of x-ray energy in the beamline, which is in the range of 2–15 keV or less. Therefore, relatively good absorption contrast can be obtained for plastic materials, biomaterials, and the like. Since nondestructive imaging of the processed shape by x-ray lithography is possible, it is a very useful system in processing and evaluation can be performed simultaneously. This system also enables us to obtain the live images with keeping the creature alive in liquid using an indirect x-ray imaging system which converts x-ray images to visible light images through the fluorescent plate.
  • Akira Heya, Hideo Otsuka, Koji Sumitomo
    Journal of Photopolymer Science and Technology 36(4) 253-259 2023年6月15日  
  • Shunya Saegusa, Tsunemasa Saiki, Sho Amano, Takao Fukuoka, Yukako Takizawa, Masatoshi Takahashi, Keisuke Yoshiki, Kaito Fujitani, Koji Sumitomo, Yuichi Utsumi, Akinobu Yamaguchi
    Journal of Photopolymer Science and Technology 36(3) 127-132 2023年  
    For the implementation of SERS in microfluidic devices, we propose a rotor structure using SAW as a simple aggregation mechanism. In this study, 45 nm gold nanoparticles were agglomerated in a rotor and evaluated. It was found that the aggregate size increased with increasing supply energy, indicating that this mechanism contributes to aggregate formation. SERS measurements using this mechanism were also successfully performed.
  • Akira Heya, Koji Sumitomo
    Journal of Photopolymer Science and Technology 35(4) 351-357 2022年12月16日  査読有り
  • Akira HEYA, Akinori Fujibuchi, Masahiro Hirata, Kazuhiro KANDA, Yoshiaki Matsuo, Junichi INAMOTO, Koji Sumitomo
    Japanese Journal of Applied Physics 62(SC) SC1028-SC1028 2022年12月16日  査読有り
    <jats:title>Abstract</jats:title> <jats:p>The reduction of graphene oxide (GO) through atomic hydrogen annealing (AHA) and soft X-ray irradiation is investigated using microwell substrates with μm-sized holes with and without Ni underlayers. The GO film is reduced through AHA at 170 °C and soft X-ray irradiation at 150 °C. In contrast, some GO films are not only reduced but also amorphized through soft X-ray irradiation. The effect of the Ni underlayer on GO reduction differs between AHA and soft X-ray irradiation. In AHA, the difference in GO reduction between SiO<jats:sub>2</jats:sub> and Ni underlayer was originated from the atomic hydrogen density on sample surface. On the other hand, in soft X-ray irradiation, the difference in GO reduction between SiO<jats:sub>2</jats:sub> and the Ni underlayer originates from the excited electrons generated by soft X-ray irradiation. Reduction without damage is more likely to occur in the suspended GO than in the supported GO.</jats:p>
  • Ryo Yamasaki, Akira Heya, Naoto Matsuo, Koji Sumitomo
    e-Journal of Surface Science and Nanotechnology 21(1) 46-54 2022年12月3日  査読有り
  • Azusa Oshima, Kohei Nakanishi, Nahoko Kasai, Hiroshi Nakashima, Kanta Tsumoto, Koji Sumitomo
    Langmuir 38(18) 5464-5471 2022年5月10日  査読有り
  • Akira Heya, Kazuhiro Kanda, Ryo Yamasaki, Koji Sumitomo
    Japanese Journal of Applied Physics 61({SC}) 2022年5月1日  査読有り
  • Kai Hashino, Daiya Mombayashi, Yuto Nakatani, Azusa Oshima, Masumi Yamaguchi, Akira Heya, Koji Sumitomo
    Japanese Journal of Applied Physics 2022年3月1日  査読有り責任著者
  • Daiya Mombayashi, Ami Yasuhara, Kai Hashino, Akira Heya, Koji Sumitomo
    Sensors and Materials 33(12) 4361-4361 2021年12月27日  査読有り責任著者
  • Yuichi Haruyama, Daiki Morimoto, Akira Heya, Koji Sumitomo, Seigo Ito, Kumiko Yokota, Masahito Tagawa
    Japanese Journal of Applied Physics 60(12) 2021年12月1日  査読有り
    The effect of atomic hydrogen exposure on hydrogenated amorphous carbon (a-C:H) films was investigated by X-ray photoelectron spectroscopy (XPS). From the dependence of the wide-scan XPS spectra of an a-C:H film on atomic hydrogen exposure, it was shown that the film was etched with an etching rate of 0.2 nm min-1. In addition, by analyzing the C 1s XPS spectra, the coordination of C atoms in the a-C:H film was investigated as a function of the atomic hydrogen exposure and photoelectron emission angle. This indicated that the coordination of C atoms at the surface of the a-C:H film was not influenced by atomic hydrogen exposure. Therefore, we propose that the depth profile of a-C:H films can be measured with no damage using atomic hydrogen etching.
  • Akira Heya, Koji Sumitomo
    Japanese Journal of Applied Physics 60({SB}) 2021年5月1日  査読有り
  • Akira Heya, Masahito Niibe, Kazuhiro Kanda, Ryo Yamasaki, Koji Sumitomo
    Japanese Journal of Applied Physics 60(4) 045506-045506 2021年4月1日  査読有り
  • Akira Heya, Tetsuo Harada, Masahito Niibe, Koji Sumitomo, Takeo Watanabe
    Proceedings of SPIE - The International Society for Optical Engineering 11908 2021年  査読有り
    An extreme ultraviolet (EUV) light with a wavelength of 13.5 nm has been introduced to 7 nm FinFET technology. Optical elements such as Mo/Si multilayer mirror in lithography equipment are contaminated with hydrocarbon during the EUV light irradiation. The reflectance of the mirrors is decreased by carbon contamination. Therefore, the removal method of the carbon contamination is required for reduction of maintenance cost. The surface treatment using atomic hydrogen generated by a heated tungsten mesh, called as atomic hydrogen annealing (AHA), have been investigated for cleaning of the optical elements used in the synchrotron facility. The Au/Cr/Si substrate, Ni mirror and Ni diffraction grating with carbon contamination were cleaned and the reflectance of the mirrors was recovered by AHA. In addition, the AHA conditions could be optimized for cleaning of Mo/Si multilayer mirrors from the relationship between the treatment conditions and degradation. Furthermore, to clarify the reaction of atomic hydrogen with not only C-C bond but also C-O bond, the graphene oxide (GO) film was also treated by AHA. The C-O-C bonds in the GO films were preferentially reduced by AHA. It is found that the surface contamination consisting of hydrocarbon and/or C-O bond on the optical elements is removed without damage. The ability of atomic hydrogen to clean the optical elements had been confirmed. The findings are useful for the advanced lithography technology using EUV light.
  • Akira Heya, Ryo Yamasaki, Koji Sumitomo
    Proceedings of AM-FPD 2020 - 27th International Workshop on Active-Matrix Flatpanel Displays and Devices: TFT Technologies and FPD Materials 73-74 2020年9月1日  
    To clarify the decomposition and polymerization mechanism of pentacene (C22H14) molecules in hot mesh deposition (HMD), D2 gas was used instead of H2 gas. The nanocarbon film deposited on a Ni film/quartz substrate by HMD using D2 gas was evaluated by a laser desorption/ionization mass spectrometry (LDI-MS). The signals due to various deuterated pentacene-based precursors were observed in the LDI-MS spectrum.
  • Azusa Oshima, Hiroshi Nakashima, Koji Sumitomo
    Japanese Journal of Applied Physics 59(2) 2020年2月1日  査読有り
  • Oshima, A., Inui, N., Ueno, Y., Sumitomo, K.
    IEEJ Transactions on Electronics, Information and Systems 140(4) 421-425 2020年  査読有り
    © 2020 The Institute of Electrical Engineers of Japan. We propose the system to analyze water permeability through the lipid bilayer. The lipid bilayer suspended over microwells changes its shape when the difference of osmotic pressure is formed by solution exchange. When the solution concentration outside the microwell is lower than the inside, water permeates through the lipid bilayer membrane and bulges outward. The interference fringes observed in the suspended lipid bilayer allowed us to accurately analyze its structural changes. Water permeability through the lipid bilayer could be accurately estimated based on analysis of the changes in the interference fringes observed in the suspended lipid bilayer caused by the solution exchange.
  • Heya, A., Oonuki, T., Utimi, R., Kanda, K., Yamasaki, R., Sumitomo, K.
    Thin Solid Films 713 138365-138365 2020年  査読有り
  • 樫村吉晃, 住友弘二, 中島寛
    電気学会論文誌 C 140(4) 2020年  査読有り
  • Kashimura, Y., Sumitomo, K., Nakashima, H.
    Electronics and Communications in Japan 103(9) 2020年  査読有り
  • Heya, A., Harada, T., Niibe, M., Sumitomo, K., Watanabe, T.
    Journal of Photopolymer Science and Technology 33(4) 419-426 2020年  査読有り
    © 2020 SPST. The surface treatment using atomic hydrogen genareted by a heated tungsten mesh was investigated for the cleaning of the optical elements used in the synchrotron facility. We call the surface-tretament by the atomic hydrogen annealing (AHA). The Au and Ni mirors and Ni and Mo diffraction gratings with carbon contamination were cleaned by the chemical reaction and thermal effect due to the recombination of the atomic hydrogens during AHA. The carbon contamination was removed and the reflactance of the Au and Ni mirrors was recovered by AHA. The AHA conditions could be optimaized for cleaning of Mo/Si multilayer mirrors from the relationship between the treatment condition and degradation. In addition, to clarify the removal reaction of the carbon contamination, the two-types of amorphous carbon (a-C) films were used. The etching rate of the a-C film by AHA was strongly related to the hydrogen content, atomic density and sp2/sp3 component of a-C film.
  • Azusa Oshima, Hiroshi Nakashima, Koji Sumitomo
    Langmuir 35(36) 11725-11734 2019年9月10日  査読有り
  • Goto T, Kasai N, Filip R, Sumitomo K, Nakashima H
    Micron (Oxford, England : 1993) 126 102740-102740 2019年8月  査読有り
  • Yuto Nakatani, Kano Kawahara, Koki Harada, Azusa Oshima, Hiroshi Nakashima, Koji Sumitomo
    Japanese Journal of Applied Physics 58(SI) SIID06 2019年8月1日  査読有り
  • 大嶋梓, 住友弘二
    分析化学 68(1) 23-32 2019年1月  査読有り招待有り
  • Koji Sumitomo, Azusa Oshima
    LANGMUIR 33(46) 13277-13283 2017年11月  査読有り
    The localisation of liquid-ordered (L-o) and liquid-crystalline (La) phase domains on a silicon substrate with a microwell array is investigated. Although the phase separation of the Lo and La phases on both a giant unilamellar vesicle (GUV) and a supported membrane remains stable for a long time, the lateral diffusion of lipids across each domain boundary occurs quickly. Since the phase separation and domain arrangement are governed by the stiffness and lateral tension of the lipid membrane, the phase separation is rearranged on a rnicropatterned substrate. Similar phase separation of the Lo and La phases is observed at a lipid membrane suspended over a microwell. However, the La phase is preferred at a suspended membrane, and saturated lipids and cholesterol are excluded toward the supporting membrane on the periphery. Since the Lo domain area is reduced by anisotropic diffusion through the boundary between the suspended and supported membranes, a very slow reduction rate with a La phase domain is observed at a membrane suspended over a microwell, which is membrane. linear functional relation is observed. Finally, a localized surrounded by an Lo phase supported membrane.
  • Azusa Oshima, Koji Sumitomo
    Biochemistry and Biophysics Reports 11 58-63 2017年9月1日  査読有り
    The fusion of proteoliposomes is a promising approach for incorporating membrane proteins in artificial lipid membranes. In this study, we employed an electrostatic interaction between vesicles and supported bilayer lipid membranes (s-BLMs) to control the fusion process. We combined large unilamellar vesicles (LUVs) containing anionic lipids, which we used instead of proteoliposomes, and s-BLMs containing cationic lipids to control electrostatic interaction. Anionic LUVs were never adsorbed or ruptured on the SiO2 substrate with a slight negative charge, and selectively fused with cationic s-BLMs. The LUVs can be fused effectively to the target position. Furthermore, as the vesicle fusion proceeds and some of the positive charges are neutralized, the attractive interaction weakens and finally the vesicle fusion saturates. In other words, we can control the number of LUVs fused with s-BLMs by controlling the concentration of the cationic lipids in the s-BLMs. The fluidity of the s-BLMs after vesicle fusion was confirmed to be sufficiently high. This indicates that the LUVs attached to the s-BLMs were almost completely fused, and there were few intermediate state vesicles in the fusion process. We could control the position and amount of vesicle fusion with the s-BLMs by employing an electrostatic interaction.
  • Tetsuhiko Teshima, Hiroshi Nakashima, Nahoko Kasai, Satoshi Sasaki, Aya Tanaka, Shingo Tsukada, Koji Sumitomo
    ADVANCED FUNCTIONAL MATERIALS 26(45) 8185-8193 2016年12月  査読有り
    Microfabricated mobile electrodes, nanopallets, designed to provide adherent cells with electrical stimulation are reported. Nanopallets composed of a cross-linked silk fibroin hydrogel matrix incorporated with poly(3,4-ethyle nedioxythiophene): polystyrene sulfonate (PEDOT:PSS) are used. The silk fibroin composite is characterized not only by mechanical and electrical conductive properties, but also by its optical transparency in both the visible and ultraviolet regions, and by its biocompatibility with adherent cells. It is demonstrated that the adherent cells, including normal cell-lined cells and primary neuronal cells, loaded on the nanopallets can be manipulated while faithfully retaining their adhesive properties. By applying voltages via the nanopallets, the voltage-dependent calcium channels expressed in the cells are selectively stimulated, and this is confirmed by using confocal fluorescent microscopy during manipulation and performing multiangle observations. These features are attributed to both the mobile operation of the transparent nanopallets, and the ability to simultaneously measure electrical signals and perform fluorescent observations.
  • Kashimura, Y., Oshima, A., Sumitomo, K.
    NTT Technical Review 14(8) 2016年8月  査読有り招待有り
    Membrane proteins play vital roles in a wide variety of functions in living organisms. The development of nanobiodevices that fuse semiconductor nanotechnology and membrane proteins makes it possible to understand various biological processes as well as engineering applications. In this article, we introduce the fabrication of nanobiodevices that are functionalized by membrane proteins and designed to mimic the synaptic signal transmission mechanism in the nervous system.
  • Nahoko Kasai, Rick Lu, Roxana Filip, Toichiro Goto, Aya Tanaka, Koji Sumitomo
    ELECTROCHEMISTRY 84(5) 296-298 2016年5月  査読有り
    Neuronal patterning is useful for understanding signal propagation between neurons as well as for biosensors and cell-based assays. The patterning of living cells has been made possible by employing surface physicochemical and topographic features. This study investigated neuronal growth on patterned nanopillars. Rat cortical neurons were cultivated on quartz substrates with amorphous silicon (a-Si) and Au pillars 100 and 500 nm in diameter. The neurites grew better with the larger diameter pillars, and the partly-selective neurite growth was observed for a-Si pillars but not for Au pillars. These results reveal the possibility of controlling neuronal growth by using a-Si nanopillars. (C) The Electrochemical Society of Japan, All rights reserved.
  • Toichiro Goto, Nahoko Kasai, Rick Lu, Roxana Filip, Koji Sumitomo
    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 16(4) 3383-3387 2016年4月  査読有り
    Interfaces between single neurons and conductive substrates were investigated using focused ion beam (FIB) milling and subsequent scanning electron microscopy (SEM) observation. The interfaces play an important role in controlling neuronal growth when we fabricate neuron-nanostructure integrated devices. Cross sectional images of cultivated neurons obtained with an FIB/SEM dual system show the clear affinity of the neurons for the substrates. Very few neurons attached themselves to indium tin oxide (ITO) and this repulsion yielded a wide interspace at the neuron-ITO interface. A neuron-gold interface exhibited partial adhesion. On the other hand, a neuron-titanium interface showed good adhesion and small interspaces were observed. These results are consistent with an assessment made using fluorescence microscopy. We expect the much higher spatial resolution of SEM images to provide us with more detailed information. Our study shows that the interface between a single neuron and a substrate offers useful information as regards improving surface properties and establishing neuron-nanostructure integrated devices.
  • 塚田 弥生[哲翁], 村田 広茂, 淀川 顕司, 清水 渉, 河西 奈保子, 住友 弘二, 塚田 信吾
    心電図 36(Suppl.1) S-34 2016年2月  
  • Maia Godonoga, Ting-Yu Lin, Azusa Oshima, Koji Sumitomo, Marco S. L. Tang, Yee-Wai Cheung, Andrew B. Kinghorn, Roderick M. Dirkzwager, Cunshan Zhou, Akinori Kuzuya, Julian A. Tanner, Jonathan G. Heddle
    SCIENTIFIC REPORTS 6 2016年2月  査読有り
    DNA aptamers have potential for disease diagnosis and as therapeutics, particularly when interfaced with programmable molecular technology. Here we have combined DNA aptamers specific for the malaria biomarker Plasmodium falciparum lactate dehydrogenase (PfLDH) with a DNA origami scaffold. Twelve aptamers that recognise PfLDH were integrated into a rectangular DNA origami and atomic force microscopy demonstrated that the incorporated aptamers preserve their ability to specifically bind target protein. Captured PfLDH retained enzymatic activity and protein-aptamer binding was observed dynamically using high-speed AFM. This work demonstrates the ability of DNA aptamers to recognise a malaria biomarker whilst being integrated within a supramolecular DNA scaffold, opening new possibilities for malaria diagnostic approaches based on DNA nanotechnology.
  • Ruaridh Forbes, Yoshiaki Kashimura, Koji Sumitomo
    APPLIED PHYSICS EXPRESS 8(11) 2015年11月  査読有り
    To provide a platform for biodevices designed to characterize membrane proteins, we fabricated a new type of microwell sealed with a lipid membrane on a SiO2 substrate. The microwell is surrounded by a Au ring with a self-assembled monolayer, on which a lipid membrane is formed to create a seal. Fluorescence and electrophysiological studies reveal that the structure prevents unfavorable ion leakage from/ into microwells. By separating the microwells and outer regions, ion diffusion through the water layer between the membrane and the substrate is reduced. This study offers a promising approach for the functional analysis of membrane proteins. (C) 2015 The Japan Society of Applied Physics
  • Aya Tanaka, Hiroshi Nakashima, Yoshiaki Kashimura, Koji Sumitomo
    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 477 63-69 2015年7月  査読有り
    A membrane protein is one of the targets for understanding cellular function and for biosensor and drug screening applications. An artificial lipid membrane suspended over microwells can act as a platform when we attempt to realize a nanobio device based on a membrane protein function. With the aim of preparing a lipid membrane array on a substrate, we investigated lipid membrane formation on a hydrogel-confined micropatterned substrate because a hydrogel can support a lipid membrane both mechanically and functionally. The interaction between the positive charge of the hydrogel and the negative charge of the substrate surface allows the hydrogel to be confined in the microwells. When small unilamellar vesicles with a diameter smaller than the aperture of the microwells were added to the solution over the substrate, hydrogel-supported lipid membranes were formed. The vesicle fusion was facilitated by the electrostatic interaction between the vesicle charge and the opposite charge of the hydrogel. The continuous and fluid properties of the hydrogel-supported lipid membrane were confirmed by the fluorescent recovery after photobleaching method. Our results suggest that support provided by hydrogels in the microwells enables us to arrange membrane proteins on a nanobio device by the direct formation of a planar lipid membrane from proteoliposomes with a small diameter. (C) 2015 Elsevier B.V. All rights reserved.
  • Aya Tanaka, Ryosuke Tanaka, Nahoko Kasai, Shingo Tsukada, Takaharu Okajima, Koji Sumitomo
    JOURNAL OF STRUCTURAL BIOLOGY 191(1) 32-38 2015年7月  査読有り
    Apoptosis plays an important role in many physiologic and pathologic conditions. The biochemical and morphological characteristics of apoptosis including cellular volume decrease, cell membrane blebbing, and phosphatidylserine translocation from the inner to the outer leaflet of the cell membrane are considered important events for phagocyte detection. Despite its importance, the relationship between the biological and morphological changes in a living cell has remained controversial. Scanning ion conductance microscopy is a suitable technique for investigating a series of these changes, because it allows us to observe the morphology of living cells without any mechanical interactions between the probe and the sample surface with a high resolution. Here, we investigated the biochemical and morphological changes in single neurons during the early stages of apoptosis, including apoptotic volume decrease, membrane blebbing and phosphatidylserine translocation, by using scanning ion conductance microscopy. Time-course imaging of apoptotic neurons showed there was a reduction in apoptotic volume after exposure to staurosporine and subsequent membrane bleb formation, which has a similar onset time to phosphatidylserine translocation. Our results show that a reduction in cellular volume is one of the earliest morphological changes in apoptosis, and membrane blebbing and phosphatidylserine translocation occur as subsequent biological and morphological changes. This is the first report to describe this series of morphological and biochemical changes ranging from an apoptotic volume decrease to membrane blebbing and PS translocation by scanning ion conductance microscopy (SICM). This new and direct imaging technique will provide new insight into the relationship between biochemical events inside a cell and cellular morphological changes. (C) 2015 Elsevier Inc. All rights reserved.
  • Toichiro Goto, Yuichi Harada, David Cox, Koji Sumitomo
    JAPANESE JOURNAL OF APPLIED PHYSICS 53(9) 2014年9月  査読有り
    We propose a hydrophilic-raised-ring structure at the aperture of a hole for the efficient suspension of a lipid bilayer. This ring structure can be fabricated by using a combination consisting of a focused ion beam (FIB) and a hydrogen silsesquioxane (HSQ) negative electron beam (EB) resist layer on a substrate. Negative EB resist at the aperture of a hole can be selectively reacted with a scattered gallium ion beam during the FIB milling process, and a ring structure can be obtained by employing a development process. Assessments of the cross section of the ring revealed a two-step structure. The suspension of lipid bilayers on the ring structures was assessed by observing the green fluorescence of calcein dye inside the holes. Our observation of fluorescent images showed that the lipid bilayers on the ring structures sealed the calcein solutions. This result indicates that our fabrication processes can be used to produce nanobio devices that need lipid bilayer suspensions. (C) 2014 The Japan Society of Applied Physics
  • Y. Kashimura, K. Sumitomo, K. Furukawa
    MATERIALS RESEARCH EXPRESS 1(3) 2014年9月  査読有り
    The electrostatic control of lipid bilayer self-spreading was investigated using a device equipped with a nanogap gate. A series of mixtures containing negatively charged and uncharged lipids were employed to tune the charge of a membrane. We found that when a voltage is applied on a lipid bilayer passing through a nanogap, the effect of a voltage application on the dynamics depended largely on the charge of the membrane. For rich charged lipid compositions (&gt;10 mol%), the self-spreading was electrostatically controlled applying an electric field to the nanogap. The origin of the behaviour is the electrostatic trapping of charged lipids. The trapped lipids close the nanogap gate, thus preventing any lipid molecules from passing through it. For poor charged lipid compositions (similar to 1 mol%), no electrostatic trapping occurred even when a lipid bilayer reached the nanogap. Instead, we observed the cessation of self-spreading after a sufficient post-passage time interval, indicating that the translational flow force of self-spreading overcomes the trapping force. For uncharged lipid compositions, there was no electrostatic trapping throughout the measurement. The results suggest that the lipid charge plays a vital role in the electrostatic control mechanism and allow us to control lipid bilayer formation both spatially and temporally.
  • Nahoko Kasai, Rick Lu, Touichiro Goto, Aya Tanaka, Shingo Tsukada, Yuichi Harada, Koji Sumitomo
    e-Journal of Surface Science and Nanotechnology 12 179-184 2014年4月19日  査読有り
    We observed neurons cultivated on an indium tin oxide (ITO) substrate using scanning electron microscopy (SEM) whose high spatial resolution allows us to observe neuronal morphological details. First, we optimized the fixation condition of cultivated neurons for SEM observation. The first fixation with paraformaldehyde and glutaraldehyde, and the second fixation with OsO4 were both necessary to avoid cell removal during the preparation before SEM observation. After optimization, we examined the morphological changes of neurons under an apoptotic condition, induced by staurosporine, by using both SEM and an immunochemical technique. Interestingly, the addition of staurosporine induced both apoptosis and a necrotic phenomenon. Immunostaining analysis revealed late-stage apoptosis after early-stage apoptosis, which was observed induced in cortical neurons by staurosporine for the first time. We confirmed that the SEM imaging of neurons is very useful as regards observing the apoptotic process. It is also a promising tool for understanding such neuronal activities as synaptic formation and axonal growth. Further examination of the interaction between neurons and substrates will contribute to the implementation of the artificial neurological devices. © 2014 The Surface Science Society of Japan.
  • Youichi Shinozaki, Aya Tanaka, Nahoko Kasai, Keiichi Torimitsu, Koji Sumitomo
    APPLIED PHYSICS EXPRESS 7(2) 2014年2月  査読有り
    We investigated structural changes in ligand-gated ion channel proteins reconstituted into supported lipid bilayers. The ion channels' extracellular parts were highly dynamic and exhibited agonist-induced changes, which were inhibited by antagonists. Our data demonstrate that, by using small exogenously applied compounds (i.e., ligands), ion channel proteins reconstituted into supported lipid bilayers on a substrate can be controlled. (C) 2014 The Japan Society of Applied Physics
  • Aya Tanaka, Yoshiaki Kashimura, Eiichi Kuramochi, Koji Sumitomo
    APPLIED PHYSICS EXPRESS 7(1) 2014年1月  査読有り
    To provide a platform for a nanobiodevice, we fabricated microcavities on a Si/SiO2 substrate covered by a thin SiO2 layer with nanohole arrays that we call a pepper shaker substrate. Fluorescence and atomic force microscopy images showed that the structure of the pepper shaker substrate improved both the probability of membrane sealing over the microcavities by rupturing giant unilameller vesicles and the lifetime of the lipid membrane suspended over the microcavities. The success of this study reveals the potential for fabricating an artificial cell array as a tool for the functional and high throughput analysis of membrane proteins. (C) 2014 The Japan Society of Applied Physics
  • Tsukada, S., Kasai, N., Kawano, R., Takagahara, K., Fujii, K., Sumitomo, K.
    NTT Technical Review 12(4) 2014年1月  査読有り招待有り
    We developed a conductive fiber by coating the surface of silk or synthetic fiber with a conductive polymer and fabricated wearable electrodes to achieve long-term biosignal monitoring. This new bioelectrode made of a complex conductive material is flexible, biocompatible, and hydrophilic and allows stable recording equivalent to that obtained with conventional medical electrodes but without the need for any electrolyte paste, which can irritate the patients&#039; skin. We can expect this wearable electrode to be utilized in various applications related to sports, health improvement, and early medical diagnosis by providing long-term biosignal monitoring without patient discomfort or irritation.
  • Aya Tanaka, Hiroshi Nakashima, Yoshiaki Kashimura, Koji Sumitomo
    JAPANESE JOURNAL OF APPLIED PHYSICS 53(1) 2014年1月  査読有り
    We successfully sealed a gel-confined microwell array on a Si substrate with a lipid membrane by rupturing giant unilamellar vesicles. Atomic force microscope measurements suggested that gel with a hillock structure supported lipid membranes gently because of its soft and elastic properties and improved the stability of the lipid membrane over the microwell array. We found that the lipid membrane sealed the gel-confined microwells and no Ca2+ leakage through the lipid membrane was observed within the detection range of our calcium indicator. We expect that gel with properties similar to cytoplasm consisting of a cytoskeletal network is a potential candidate for providing lipid membranes with mechanical support. This study proposes an artificial cell array system for fluorescence and atomic force microscope observations of functional membrane proteins on silicon-based nanobiodevices. (C) 2014 The Japan Society of Applied Physics
  • Ali D. Malay, Jonathan G. Heddle, Satoshi Tomita, Kenji Iwasaki, Naoyuki Miyazaki, Koji Sumitomo, Hisao Yanagi, Ichiro Yamashita, Yukiharu Uraoka
    NANO LETTERS 12(4) 2056-2059 2012年4月  査読有り
    Gold nanoparticles are generally considered to be biologically inactive. However, in this study we show that the addition of 1.4 nm diameter gold nanoparticle induces the remodeling of the ring-shaped protein TRAP into a hollow, capsid-like configuration. This structural remodeling is dependent upon the presence of cysteine residues on the TRAP surface as well as the specific type of gold nanoparticle. The results reveal an apparent novel catalytic role of gold nanoparticles.
  • Koji Sumitomo, Arianna McAllister, Yukihiro Tamba, Yoshiaki Kashimura, Aya Tanaka, Youichi Shinozaki, Keiichi Torimitsu
    Biosensors and Bioelectronics 31(1) 445-450 2012年1月  査読有り
    For the functional analysis of ion channel activity, an artificial lipid bilayer suspended over microwells was formed that ruptured giant unilamellar vesicles on a Si substrate. Ca2+ion indicators (fluo-4) were confined in the microwells by sealing the microwells with a lipid bilayer. An overhang formed at the microwells prevented the lipid membrane from falling into them and allowed the stable confinement of the fluorescent probes. The transport of Ca2+ions through the channels formed by α-hemolysin inserted in a lipid membrane was analyzed by employing the fluorescence intensity change of fluo-4 in the microwells. The microwell volume was very small (1-100fl), so a highly sensitive monitor could be realized. The detection limit is several tens of ions/s/μm2, and this is much smaller than the ion current in a standard electrophysiological measurement. Smaller microwells will make it possible to mimic a local ion concentration change in the cells, although the signal to noise ratio must be further improved for the functional analysis of a single channel. We demonstrated that a microwell array with confined fluorescent probes sealed by a lipid bilayer could constitute a basic component of a highly sensitive biosensor array that works with functional membrane proteins. This array will allow us to realize high throughput and parallel testing devices. © 2011 Elsevier B.V.
  • Youichi Shinozaki, Koji Sumitomo, Aya Tanaka, Nahoko Kasai, Keiichi Torimitsu
    APPLIED PHYSICS EXPRESS 4(10) 2011年10月  査読有り
    We investigated techniques for regulating the orientation of ion channel-type membrane proteins reconstituted in lipid bilayers. Free ion channel proteins aligned their long axis parallel to the substrate. In contrast, immunochemical and atomic force microscopy images revealed that ion channels reconstituted in supported lipid bilayers oriented upward, with their long axis perpendicular to the substrate. Our data demonstrates that the reconstitution of ion channels into planar lipid bilayers by rupturing small unilamellar proteoliposomes is a promising way of aligning ion channels upward in a membrane and of obtaining ion channels with controlled functions. (C) 2011 The Japan Society of Applied Physics
  • 田中 あや, 篠崎 陽一, 住友 弘二, 鳥光 慶一
    マグネシウム 29(2) 67-68 2010年11月  

MISC

 151

担当経験のある科目(授業)

 10

共同研究・競争的資金等の研究課題

 6

産業財産権

 115