長島 一樹 (ナガシマ カズキ)

電子科学研究所 物質科学研究部門教授
Last Updated :2024/12/06

■研究者基本情報

学位

  • 博士(工学), 大阪大学, 2010年03月

Researchmap個人ページ

研究キーワード

  • 人工嗅覚センサ
  • ナノ機能デバイス
  • ナノ材料科学

研究分野

  • ナノテク・材料, 機能物性化学
  • ナノテク・材料, 薄膜、表面界面物性
  • ナノテク・材料, ナノ材料科学
  • ナノテク・材料, ナノ構造化学, ナノ機能材料

■経歴

経歴

  • 2023年04月 - 現在
    北海道大学, 電子科学研究所, 教授
  • 2022年07月 - 2023年03月
    物質・材料研究機構, 磁性・スピントロニクス材料研究拠点, 外来研究者
  • 2020年05月 - 2023年03月
    東京大学, 大学院工学系研究科応用化学専攻, 准教授
  • 2019年10月 - 2023年03月
    JSTさきがけ, 「人とインタラクションの未来」領域, 研究者
  • 2021年05月 - 2022年03月
    国立研究開発法人物質・材料研究機構, 磁性・スピントロニクス材料研究拠点, 客員研究員
  • 2020年12月 - 2021年03月
    国立研究開発法人物質・材料研究機構, 磁性・スピントロニクス材料研究拠点, 客員研究員
  • 2017年12月 - 2020年04月
    九州大学, 先導物質化学研究所ナノ融合材料分野, 准教授
  • 2018年04月 - 2020年03月
    大阪大学, 産業科学研究所ナノシステム設計分野, 招聘准教授
  • 2017年04月 - 2018年03月
    大阪大学, 産業科学研究所ナノシステム設計分野, 招聘教員
  • 2015年04月 - 2017年11月
    九州大学, 先導物質化学研究所ナノ融合材料分野, 助教
  • 2010年04月 - 2015年03月
    大阪大学, 産業科学研究所極微材料プロセス研究分野, 特任助教
  • 2008年04月 - 2010年04月
    (独)日本学術振興会, 特別研究員(DC1)
  • 2008年04月 - 2010年03月
    大阪大学大学院, 基礎工学研究科物質創成専攻, 博士後期課程 博士(工学)
  • 2006年04月 - 2008年03月
    大阪大学大学院, 基礎工学研究科物質創成専攻, 博士前期課程 修士(工学)
  • 2002年04月 - 2006年03月
    大阪大学, 基礎工学部電子物理科学科, 学士(工学)

学歴

  • 2008年04月 - 2010年03月, 大阪大学大学院, 基礎工学研究科, 物質創成専攻博士後期課程
  • 2006年04月 - 2008年03月, 大阪大学大学院, 基礎工学研究科, 物質創成専攻博士前期課程
  • 2002年04月 - 2006年03月, 大阪大学, 基礎工学部, 電子物理科学科

委員歴

  • 2023年07月 - 2024年05月
    18th International Conference on Electronic Materials 2024 (IUMRS-ICEM2024), International Advising Committee
  • 2023年05月 - 2024年04月
    応用物理学会, 講演会企画・運営委員
  • 2018年04月 - 2024年04月
    応用物理学会, プログラム編集委員, 学協会
  • 2023年07月 - 2023年12月
    Mini Workshop on Functional Materials Science (Mini FMS 2023), Organizing Committee
  • 2021年03月 - 2023年02月
    電子材料シンポジウム, 実行委員会 総務委員
  • 2019年09月 - 2022年08月
    The 5th International Conference of Young Researchers on Advanced Materials (ICYRAM2022), General Chair
  • 2021年10月
    7th International Congress on Science, Technology and Technology-based Innovation (STT47), Scientific Committee
  • 2020年11月 - 2021年03月
    第68回応用物理学会春季学術講演会, 実行委員
  • 2020年12月
    The 5th International Conference on Smart Materials and Nanotechnology (SmartMat@2020), Academic Committee
  • 2020年10月
    46th International Congress on Science, Technology and Technology-based Innovation (STT46), Scientific Committee
  • 2018年03月 - 2020年02月
    電子材料シンポジウム, 実行委員会 会場委員, 学協会
  • 2017年06月
    The 3rd International Conference on Applied Physics and Material Applications (ICAPMA 2017), International Committee, 学協会
  • 2013年11月
    The 6th Thailand-Japan International Academic Conference 2013 (TJIA 2013), Advisory Committee, 学協会

■研究活動情報

受賞

  • 2024年05月, 公益財団法人本多記念会, 第45回本多記念研究奨励賞               
    長島 一樹
  • 2023年09月, 公益財団法人応用物理学会, 第22回JSAPフォト&イラストコンテスト 最優秀賞               
    長島 一樹
  • 2022年12月, 株式会社知財図鑑, 知財番付2022 東ノ横綱               
    東京大学大学院工学系研究科, 九州大学大学院総合理工学府, 名古屋大学大学院工学研究科, パナソニックインダストリー
  • 2022年10月, 第41回電子材料シンポジウム, Ugly Picture Contest 第1位               
    長島 一樹
  • 2022年04月, 文部科学大臣, 令和4年度科学技術分野の文部科学大臣表彰 若手科学者賞               
    長島 一樹
  • 2022年03月, 公益財団法人応用物理学会, 第19回JSAPフォト&イラストコンテスト 最優秀賞               
    長島 一樹, 高橋 綱己, 細見 拓郎, 田中 航, 柳田 剛
  • 2019年01月, The Second International Workshop by the 174th Committee JSPS on Symbiosis of Biology and Nanodevices, Poster Award               
    Kazuki Nagashima
  • 2018年06月, 公益社団法人新化学技術推進協会, 第7回新化学技術研究奨励賞               
    長島 一樹
  • 2018年03月, イムラ・ジャパン株式会社, 第2回イムラ・ジャパン賞               
    長島 一樹
  • 2018年01月, 愛知県産業労働部産業技術科学課, 第12回わかしゃち奨励賞 最優秀賞               
    長島 一樹
  • 2017年11月, 第36回電子材料シンポジウム, EMS賞               
    長島 一樹
  • 2017年01月, 九州大学エネルギーウィーク2017若手成果発表会, 優秀賞               
    長島 一樹
  • 2016年05月, 11th Asia-Pacific Microscopy Conference, Art Photo Contest Award               
    Kazuki Nagashima
  • 2014年11月, 一般社団法人日本粉体工業技術協会, 研究奨励賞               
    長島 一樹
  • 2014年09月, 公益社団法人応用物理学会, 第36回応用物理学会講演奨励賞               
    長島 一樹
  • 2013年11月, 一般財団法人大阪科学技術センター, 第2回ネイチャー・インダストリー・アワード 特別賞               
    長島 一樹
  • 2013年11月, 一般財団法人エヌエフ基金, 第2回エヌエフ研究開発奨励賞               
    長島 一樹
  • 2013年08月, 大阪大学総長奨励賞(研究部門)               
    長島 一樹
  • 2013年03月, 公益財団法人応用物理学会, 第1回 JSAP Photo Contest 最優秀賞               
    長島 一樹
  • 2013年02月, 公益財団法人井上科学振興財団, 第29回井上研究奨励賞               
    長島 一樹
  • 2012年12月, 8th Handai Nanoscience and Nanotechnology International Symposium, Young Researcher Best Poster Award               
    Kazuki Nagashima
  • 2012年10月, 25th International Microprocesses and Nanotechnology Conference, MNC 2011 Young Author’s Award               
    Kazuki Nagashima
  • 2012年04月, 公益財団法人日本科学協会, 平成23年度笹川科学研究奨励賞               
    長島 一樹
  • 2012年04月, 公益財団法人船井情報科学振興財団, 第11回船井研究奨励賞               
    長島 一樹
  • 2012年01月, 15th SANKEN International Symposium 2012, Best Poster Award               
    Kazuki Nagashima
  • 2011年07月, The 11th International Symposium on Sputtering & Plasma Processes (ISSP 2011), Best Poster Award               
    Kazuki Nagashima
  • 2011年06月, ナノ学会第九回大会, 若手優秀発表賞               
    長島 一樹
  • 2011年02月, 日本材料学会半導体エレクトロニクス部門委員会, 平成22年度講演奨励賞               
    長島 一樹
  • 2010年12月, 社団法人日本粉体工業技術協会, 研究奨励賞               
    長島 一樹
  • 2009年10月, 粉体工学会2009年度秋期研究発表会, BP賞               
    長島 一樹
  • 2009年09月, 5th Handai Nanoscience and Nanotechnology International Symposium, Young Researcher Best Poster Award               
    Kazuki Nagashima
  • 2008年09月, 4th Handai Nanoscience and Nanotechnology International Symposium, Young Researcher Best Poster Award               
    Kazuki Nagashima
  • 2008年02月, 大阪大学基礎工学研究科物質創成専攻, 物質創成専攻長賞               
    長島 一樹
  • 2008年01月, 1st Global COE International Symposium, Student Paper Award               
    Kazuki Nagashima

論文

  • Early Cancer Detection via Multi-microRNA Profiling of Urinary Exosomes Captured by Nanowires.
    Takao Yasui, Atsushi Natsume, Takeshi Yanagida, Kazuki Nagashima, Takashi Washio, Yuki Ichikawa, Kunanon Chattrairat, Tsuyoshi Naganawa, Mikiko Iida, Yotaro Kitano, Kosuke Aoki, Mika Mizunuma, Taisuke Shimada, Kazuya Takayama, Takahiro Ochiya, Tomoji Kawai, Yoshinobu Baba
    Analytical chemistry, 2024年10月18日, [国際誌]
    英語, 研究論文(学術雑誌), Multiple microRNAs encapsulated in extracellular vesicles (EVs) including exosomes, unique subtypes of EVs, differ in healthy and cancer groups of people, and they represent a warning sign for various cancer scenarios. Since all EVs in blood cannot be transferred from donor to recipient cells during a single blood circulation, kidney filtration could pass some untransferred EVs from blood to urine. Previously, we reported on the ability of zinc oxide nanowires to capture EVs based on surface charge and hydrogen bonding; these nanowires extracted massive numbers of microRNAs in urine, seeking cancer-related microRNAs through statistical analysis. Here, we report on the scalability of the nanowire performance capability to comprehensively capture EVs, including exosomes, in urine, extract microRNAs from the captured EVs in situ, and identify multiple microRNAs in the extracted microRNAs differing in noncancer and lung cancer subjects through machine learning-based analysis. The nanowire-based extraction allowed the presence of about 2500 species of urinary microRNAs to be confirmed, meaning that urine includes almost all human microRNA species. The machine learning-based analysis identified multiple microRNAs from the extracted microRNA species. The ensembles could classify cancer and noncancer subjects with the area under the receiver operating characteristic curve of 0.99, even though the former were staged early.
  • Urinary dengue NS1 detection on Au-decorated ZnO nanowire platform.
    Kannika Sitthisuwannakul, Ratchanon Sukthai, Zetao Zhu, Kazuki Nagashima, Kunanon Chattrairat, Supranee Phanthanawiboon, Annop Klamchuen, Sakon Rahong, Yoshinobu Baba, Takao Yasui
    Biosensors & bioelectronics, 254, 116218, 116218, 2024年06月15日, [国際誌]
    英語, 研究論文(学術雑誌), Biodetection for non-invasive diagnostics of fluids, especially urine, remains a challenge to scientists due to low target concentrations. And biological complexes of the detection target may contain contaminants that also interfere with any assay. Dengue non-structural 1 protein (Dengue NS1) is an important biomarker for dengue hemorrhagic fever and dengue shock syndrome. Here, we developed an Au-decorated nanowire platform and applied it with a sandwich fluorophore-linked immunosorbent well plate assay (FLISA) to detect Dengue NS1 in urine. For the platform, we fabricated zinc oxide (ZnO) nanowires to provide a high surface area and then coated them with gold nanoparticles (ZnO/Au nanowires) to simply modify the Dengue NS1 antibody and enhance the fluorescence intensity. Our platform employs a sandwich FLISA that exhibits high sensitivity, specifically detecting Dengue NS1 with a limit of detection (LOD) of 1.35 pg/mL. This LOD was 4500-fold lower than the LOD of a commercially available kit for Dengue NS1 enzyme-linked immunosorbent assay. We believe that our ZnO/Au nanowire platform has the potential to revolutionize the field of non-invasive diagnostics for dengue.
  • On-Site Stimulation of Dendritic Cells by Cancer-Derived Extracellular Vesicles on a Core-Shell Nanowire Platform.
    Min Zhang, Miki Ono, Shota Kawaguchi, Mikiko Iida, Kunanon Chattrairat, Zetao Zhu, Kazuki Nagashima, Takeshi Yanagida, Junya Yamaguchi, Hiroyoshi Nishikawa, Atsushi Natsume, Yoshinobu Baba, Takao Yasui
    ACS applied materials & interfaces, 2024年05月28日, [国際誌]
    英語, 研究論文(学術雑誌), Extracellular vesicles (EVs) contain a subset of proteins, lipids, and nucleic acids that maintain the characteristics of the parent cell. Immunotherapy using EVs has become a focus of research due to their unique features and bioinspired applications in cancer treatment. Unlike conventional immunotherapy using tumor fragments, EVs can be easily obtained from bodily fluids without invasive actions. We previously fabricated nanowire devices that were specialized for EV collection, but they were not suitable for cell culturing. In this study, we fabricated a ZnO/Al2O3 core-shell nanowire platform that could collect more than 60% of the EVs from the cell supernatant. Additionally, we could continue to culture dendritic cells (DCs) on the platform as an artificial lymph node to investigate cell maturation into antigen-presenting cells. Finally, using this platform, we reproduced a series of on-site immune processes that are among the pivotal immune functions of DCs and include such processes as antigen uptake, antigen presentation, and endocytosis of cancer-derived EVs. This platform provides a new ex vivo tool for EV-DC-mediated immunotherapies.
  • Discrimination of extracellular miRNA sources for the identification of tumor-related functions based on nanowire thermofluidics
    Kunanon Chattrairat, Akira Yokoi, Min Zhang, Mikiko Iida, Kosuke Yoshida, Masami Kitagawa, Ayuka Niwa, Masatoshi Maeki, Takeshi Hasegawa, Takeshi Yokoyama, Yoshikazu Tanaka, Yusuke Miyazaki, Wataru Shinoda, Manabu Tokeshi, Kazuki Nagashima, Takeshi Yanagida, Hiroaki Kajiyama, Yoshinobu Baba, Takao Yasui
    Device, 100363, 100363, Elsevier BV, 2024年04月
    研究論文(学術雑誌)
  • Engineering Interface Defects and Interdiffusion at the Degenerate Conductive In2O3/Al2O3 Interface for Stable Electrodes in a Saline Solution.
    Zetao Zhu, Takao Yasui, Xixi Zhao, Quanli Liu, Shu Morita, Yan Li, Akira Yonezu, Kazuki Nagashima, Tsunaki Takahashi, Minoru Osada, Ryotaro Matsuda, Takeshi Yanagida, Yoshinobu Baba
    ACS applied materials & interfaces, 15, 30, 36866, 36876, 2023年07月24日, [国際誌]
    英語, 研究論文(学術雑誌), A low-temperature Al2O3 deposition process provides a simplified method to form a conductive two-dimensional electron gas (2DEG) at the metal oxide/Al2O3 heterointerface. However, the impact of key factors of the interface defects and cation interdiffusion on the interface is still not well understood. Furthermore, there is still a blank space in terms of applications that go beyond the understanding of the interface's electrical conductivity. In this work, we carried out a systematic experimental study by oxygen plasma pretreatment and thermal annealing post-treatment to study the impact of interface defects and cation interdiffusion at the In2O3/Al2O3 interface on the electrical conductance, respectively. Combining the trends in electrical conductance with the structural characteristics, we found that building a sharp interface with a high concentration of interface defects provides a reliable approach to producing such a conductive interface. After applying this conductive interface as electrodes for fabricating a field-effect transistor (FET) device, we found that this interface electrode exhibited ultrastability in phosphate-buffered saline (PBS), a commonly used biological saline solution. This study provides new insights into the formation of conductive 2DEGs at metal oxide/Al2O3 interfaces and lays the foundation for further applications as electrodes in bioelectronic devices.
  • All-in-One Nanowire Assay System for Capture and Analysis of Extracellular Vesicles from an ex Vivo Brain Tumor Model.
    Kunanon Chattrairat, Takao Yasui, Shunsuke Suzuki, Atsushi Natsume, Kazuki Nagashima, Mikiko Iida, Min Zhang, Taisuke Shimada, Akira Kato, Kosuke Aoki, Fumiharu Ohka, Shintaro Yamazaki, Takeshi Yanagida, Yoshinobu Baba
    ACS nano, 17, 3, 2235, 2244, 2023年01月19日, [国際誌]
    英語, 研究論文(学術雑誌), Extracellular vesicles (EVs) have promising potential as biomarkers for early cancer diagnosis. The EVs have been widely studied as biological cargo containing essential biological information not only from inside vesicles such as nucleic acids and proteins but also from outside vesicles such as membrane proteins and glycolipids. Although various methods have been developed to isolate EVs with high yields such as captures based on density, size, and immunoaffinity, different measurement systems are needed to analyze EVs after isolation, and a platform that enables all-in-one analysis of EVs from capture to detection in multiple samples is desired. Since a nanowire-based approach has shown an effective capability for capturing EVs via surface charge interaction compared to other conventional methods, here, we upgraded the conventional well plate assay to an all-in-one nanowire-integrated well plate assay system (i.e., a nanowire assay system) that enables charge-based EV capture and EV analysis of membrane proteins. We applied the nanowire assay system to analyze EVs from brain tumor organoids in which tumor environments, including vascular formations, were reconstructed, and we found that the membrane protein expression ratio of CD31/CD63 was 1.42-fold higher in the tumor organoid-derived EVs with a p-value less than 0.05. Furthermore, this ratio for urine samples from glioblastoma patients was 2.25-fold higher than that from noncancer subjects with a p-value less than 0.05 as well. Our results demonstrated that the conventional well plate method integrated with the nanowire-based EV capture approach allows users not only to capture EVs effectively but also to analyze them in one assay system. We anticipate that the all-in-one nanowire assay system will be a powerful tool for elucidating EV-mediated tumor-microenvironment crosstalk.
  • Nanocellulose Paper Semiconductor with a 3D Network Structure and Its Nano–Micro–Macro Trans-Scale Design
    Hirotaka Koga, Kazuki Nagashima, Koichi Suematsu, Tsunaki Takahashi, Luting Zhu, Daiki Fukushima, Yintong Huang, Ryo Nakagawa, Jiangyang Liu, Kojiro Uetani, Masaya Nogi, Takeshi Yanagida, Yuta Nishina
    ACS Nano, 16, 6, 8630, 8640, American Chemical Society (ACS), 2022年06月28日
    研究論文(学術雑誌)
  • Correction: Breath odor-based individual authentication by an artificial olfactory sensor system and machine learning.
    Chaiyanut Jirayupat, Kazuki Nagashima, Takuro Hosomi, Tsunaki Takahashi, Benjarong Samransuksamer, Yosuke Hanai, Atsuo Nakao, Masaya Nakatani, Jiangyang Liu, Guozhu Zhang, Wataru Tanaka, Masaki Kanai, Takao Yasui, Yoshinobu Baba, Takeshi Yanagida
    Chemical communications (Cambridge, England), 58, 44, 6465, 6465, 2022年05月30日, [国際誌]
    英語, Correction for 'Breath odor-based individual authentication by an artificial olfactory sensor system and machine learning' by Chaiyanut Jirayupat et al., Chem. Commun., 2022, DOI: https://doi.org/10.1039/D1CC06384G.
  • Breath odor-based individual authentication by an artificial olfactory sensor system and machine learning.
    Chaiyanut Jirayupat, Kazuki Nagashima, Takuro Hosomi, Tsunaki Takahashi, Benjarong Samransuksamer, Yosuke Hanai, Atsuo Nakao, Masaya Nakatani, Jiangyang Liu, Guozhu Zhang, Wataru Tanaka, Masaki Kanai, Takao Yasui, Yoshinobu Baba, Takeshi Yanagida
    Chemical communications (Cambridge, England), 58, 44, 6377, 6380, 2022年05月30日, [国際誌]
    英語, 研究論文(学術雑誌), Breath odor sensing-based individual authentication was conducted for the first time using an artificial olfactory sensor system. Using a 16-channel chemiresistive sensor array and machine learning, a mean accuracy of >97% was successfully achieved. The impact of the number of sensors on the accuracy and reproducibility was also demonstrated.
  • Core-shell Metal Oxide Nanowire Array to Analyze Adsorption Behaviors of Volatile Molecules
    Wenjun Li, Kazuki Nagashima, Takuro Hosomi, Jiangyang Liu, Tsunaki Takahashi, Guozhu Zhang, Wataru Tanaka, Masaki Kanai, Takeshi Yanagida
    Chemistry Letters, 51, 4, 424, 427, The Chemical Society of Japan, 2022年04月05日
    英語, 研究論文(学術雑誌)
  • Edge-Topological Regulation for in Situ Fabrication of Bridging Nanosensors
    Jiangyang Liu, Hao Zeng, Guozhu Zhang, Wenjun Li, Kazuki Nagashima, Tsunaki Takahashi, Takuro Hosomi, Wataru Tanaka, Masaki Kanai, Takeshi Yanagida
    Nano Letters, 22, 6, 2569, 2577, American Chemical Society ({ACS}), 2022年03月23日
    英語, 研究論文(学術雑誌)
  • Impact of Lateral SnO2 Nanofilm Channel Geometry on a 1024 Crossbar Chemical Sensor Array
    Haruka Honda, Tsunaki Takahashi, Yohsuke Shiiki, Hao Zeng, Kentaro Nakamura, Shintaro Nagata, Takuro Hosomi, Wataru Tanaka, Guozhu Zhang, Masaki Kanai, Kazuki Nagashima, Hiroki Ishikuro, Takeshi Yanagida
    ACS Sensors, 7, 2, 460, 468, American Chemical Society ({ACS}), 2022年02月25日
    英語, 研究論文(学術雑誌)
  • Water-Selective Nanostructured Dehumidifiers for Molecular Sensing Spaces.
    Jiangyang Liu, Kazuki Nagashima, Takuro Hosomi, Wenjin Lei, Guozhu Zhang, Tsunaki Takahashi, Xixi Zhao, Yosuke Hanai, Atsuo Nakao, Masaya Nakatani, Wataru Tanaka, Hikaru Saito, Masaki Kanai, Taisuke Shimada, Takao Yasui, Yoshinobu Baba, Takeshi Yanagida
    ACS sensors, 7, 2, 534, 544, 2022年02月25日, [国際誌]
    英語, 研究論文(学術雑誌), Humidity and moisture effects, frequently called water poisoning, in surroundings are inevitable for various molecular sensing devices, strongly affecting their sensing characteristics. Here, we demonstrate a water-selective nanostructured dehumidifier composed of ZnO/TiO2/CaCl2 core-shell heterostructured nanowires for molecular sensing spaces. The fabricated nanostructured dehumidifier is highly water-selective without detrimental adsorptions of various volatile organic compound molecules and can be repeatedly operated. The thermally controllable and reversible dehydration process of CaCl2·nH2O thin nanolayers on hydrophilic ZnO/TiO2 nanowire surfaces plays a vital role in such water-selective and repeatable dehumidifying operations. Furthermore, the limitation of detection for sensing acetone and nonanal molecules in the presence of moisture (relative humidity ∼ 90%) was improved more than 20 times using nanocomposite sensors by operating the developed nanostructured dehumidifier. Thus, the proposed water-selective nanostructured dehumidifier offers a rational strategy and platform to overcome water poisoning issues for various molecular and gas sensors.
  • Spectroscopic Study for UV Irradiation Effect on Adsorpt ion State of Volatile Aldehyde at Single Crystalline ZnO Nanowire Surface
    LI Wenjun, NAGASHIMA Kazuki, WANG Chen, YOSHIDA Hideto, HOSOMI Takuro, TAKAHASHI Tsunaki, TANAKA Wataru, KANAI Masaki, YANAGIDA Takeshi
    Engineering Sciences Reports, Kyushu University, 43, 2, 37, 41, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 2022年02月, [査読有り]
    英語, 研究論文(大学,研究機関等紀要), Ultraviolet (UV) irradiation is a promising approach for enhancing a sensing response in metal oxide-based molecular sensor, however, its substantial impact on the molecular-to-surface interaction at sensor surface is poorly understood. In this study, we investigated the UV irradiation effect on adsorption state of volatile aldehyde at single crystalline zinc oxide (ZnO) nanowire surface by Fourier transform-infrared spectroscopy (FT-IR). A C9 aliphatic aldehyde, nonanal, was employed as an analyte. We found that oxidation of adsorbed nonanal was significantly promoted by the UV irradiation. A wavelength dependence implied that the photogenerated carriers play a crucial role in the enhanced oxidation. Our finding would be beneficial for designing the performances of metal oxide nanowire-based molecular sensing devices.
  • Mechanistic Approach for Long-Term Stability of a Polyethylene Glycol–Carbon Black Nanocomposite Sensor
    Wenjun Li, Kazuki Nagashima, Takuro Hosomi, Chen Wang, Yosuke Hanai, Atsuo Nakao, Atsushi Shunori, Jiangyang Liu, Guozhu Zhang, Tsunaki Takahashi, Wataru Tanaka, Masaki Kanai, Takeshi Yanagida
    ACS Sensors, 7, 1, 151, 158, American Chemical Society ({ACS}), 2022年01月28日
    英語, 研究論文(学術雑誌)
  • Surface Dissociation Effect on Phosphonic Acid Self-Assembled Monolayer Formation on ZnO Nanowires
    Kentaro Nakamura, Tsunaki Takahashi, Takuro Hosomi, Yu Yamaguchi, Wataru Tanaka, Jiangyang Liu, Masaki Kanai, Kazuki Nagashima, Takeshi Yanagida
    ACS Omega, 7, 1, 1462, 1467, American Chemical Society ({ACS}), 2022年01月11日
    英語, 研究論文(学術雑誌)
  • Molecular profiling of extracellular vesicles via charge-based capture using oxide nanowire microfluidics.
    Takao Yasui, Piyawan Paisrisarn, Takeshi Yanagida, Yuki Konakade, Yuta Nakamura, Kazuki Nagashima, Marina Musa, Ivan Adiyasa Thiodorus, Hiromi Takahashi, Tsuyoshi Naganawa, Taisuke Shimada, Noritada Kaji, Takahiro Ochiya, Tomoji Kawai, Yoshinobu Baba
    Biosensors & bioelectronics, 194, 113589, 113589, 2021年12月15日, [国際誌]
    英語, 研究論文(学術雑誌), Extracellular vesicles (EVs) have shown promising features as biomarkers for early cancer diagnoses. The outer layer of cancer cell-derived EVs consists of organotropic metastasis-induced membrane proteins and specifically enriched proteoglycans, and these molecular compositions determine EV surface charge. Although many efforts have been devoted to investigating the correlation between EV subsets obtained through density-, size-, and immunoaffinity-based captures and expressed membrane proteins, understanding the correlation between EV subsets obtained through surface charge-based capture and expressed membrane proteins is lacking. Here, we propose a methodology to profile membrane proteins of EV subsets obtained through surface charge-based capture. Nanowire-induced charge-based capture of EVs and in-situ profiling of EV membrane proteins are the two key methodology points. The oxide nanowires allowed EVs to be obtained through surface charge-based capture due to the diverse isoelectric points of the oxides and the large surface-to-volume ratios of the nanowire structures. And, with the ZnO nanowire device, whose use does not require any purification and concentration processes, we demonstrated the correlation between negatively-charged EV subsets and expressed membrane proteins derived from each cell. Furthermore, we determined that a colon cancer related membrane protein was overexpressed on negatively charged surface EVs derived from colon cancer cells.
  • Image Processing and Machine Learning for Automated Identification of Chemo-/Biomarkers in Chromatography–Mass Spectrometry
    Chaiyanut Jirayupat, Kazuki Nagashima, Takuro Hosomi, Tsunaki Takahashi, Wataru Tanaka, Benjarong Samransuksamer, Guozhu Zhang, Jiangyang Liu, Masaki Kanai, Takeshi Yanagida
    Analytical Chemistry, 93, 44, 14708, 14715, American Chemical Society ({ACS}), 2021年11月09日
    英語, 研究論文(学術雑誌)
  • Oxide Nanowire Microfluidic Devices for Capturing Single-stranded DNAs
    Marina MUSA, Takao YASUI, Zetao ZHU, Kazuki NAGASHIMA, Miki ONO, Quanli LIU, Hiromi TAKAHASHI, Taisuke SHIMADA, Akihide ARIMA, Takeshi YANAGIDA, Yoshinobu BABA
    Analytical Sciences, 37, 8, 1139, 1145, Japan Society for Analytical Chemistry, 2021年08月10日
    研究論文(学術雑誌)
  • Fabrication of a Robust In2O3 Nanolines FET Device as a Biosensor Platform.
    Zetao Zhu, Takao Yasui, Quanli Liu, Kazuki Nagashima, Tsunaki Takahashi, Taisuke Shimada, Takeshi Yanagida, Yoshinobu Baba
    Micromachines, 12, 6, 2021年05月31日, [国際誌]
    英語, 研究論文(学術雑誌), Field-effect transistors (FETs) are attractive biosensor platforms for rapid and accurate detection of various analytes through surface immobilization of specific bio-receptors. Since it is difficult to maintain the electrical stability of semiconductors of sensing channel under physiological conditions for long periods, passivation by a stable metal oxide dielectric layer, such as Al2O3 or HfO2, is currently used as a common method to prevent damage. However, protecting the sensing channel by passivation has the disadvantage that the distance between the target and the conductive channel increases, and the sensing signal will be degraded by Debye shielding. Even though many efforts use semiconductor materials directly as channels for biosensors, the electrical stability of semiconductors in the physiological environments has rarely been studied. In this work, an In2O3 nanolines FET device with high robustness in artificial physiological solution of phosphate buffered saline (PBS) was fabricated and used as a platform for biosensors without employing passivation on the sensing channel. The FET device demonstrated reproducibility with an average threshold voltage (VTH) of 5.235 V and a standard deviation (SD) of 0.382 V. We tested the robustness of the In2O3 nanolines FET device in PBS solution and found that the device had a long-term electrical stability in PBS with more than 9 days' exposure. Finally, we demonstrated its applicability as a biosensor platform by testing the biosensing performance towards miR-21 targets after immobilizing the phosphonic acid terminated DNA probes. Since the surface immobilization of multiple bioreceptors is feasible, we demonstrate that the robust In2O3 FET device can be an excellent biosensor platform for biosensors.
  • Maximizing Conversion of Surface Click Reactions for Versatile Molecular Modification on Metal Oxide Nanowires
    Rimon Yamaguchi, Takuro Hosomi, Masaya Otani, Kazuki Nagashima, Tsunaki Takahashi, Guozhu Zhang, Masaki Kanai, Hiroshi Masai, Jun Terao, Takeshi Yanagida
    LANGMUIR, 37, 17, 5172, 5179, AMER CHEMICAL SOC, 2021年05月
    英語, 研究論文(学術雑誌), Click reactions (e.g., Huisgen cycloaddition) on metal oxide nanostructures offer a versatile and robust surface molecular modification for various applications because they form strong covalent bonds in a wide range of molecular substrates. This study reports a rational strategy to maximize the conversion rate of surface click reactions on single-crystalline ZnO nanowires by monitoring the reaction progress. p-Polarized multiple-angle incidence resolution spectrometry (pMAIRS) and Fourier-transformed infrared (FT-IR) spectroscopy were employed to monitor the reaction progress of an azide-terminated self-assembled monolayer (SAM) on single-crystalline ZnO nanowires. Although various reaction parameters including the concentration of Cu(I) catalysts, triazolyl ligands, solvents, and target alkynes were systematically examined for the surface click reactions, 10-30% of terminal azide on the nanowire surface remained unreacted. Temperature-dependent FT-IR measurements revealed that such unreacted residual azides deteriorate the thermal stability of the nanowire molecular layer. To overcome this observed conversion limitation of click reactions on nanostructure surfaces, we considered the steric hindrance around the closely packed SAM reaction points, then experimented with dispersing the azide moiety into a methyl-terminated SAM. The mixed-SAM method significantly improved the azide conversion rate to almost 100%. This reaction method enables the construction of spatially patterned molecular surface modifications on metal oxide nanowire arrays without detrimental unreacted azide groups.
  • Rational Strategy for Space-Confined Seeded Growth of ZnO Nanowires in Meter-Long Microtubes
    Ryoma Kamei, Takuro Hosomi, Eisuke Kanao, Masaki Kanai, Kazuki Nagashima, Tsunaki Takahashi, Guozhu Zhang, Takao Yasui, Jun Terao, Koji Otsuka, Yoshinobu Baba, Takuya Kubo, Takeshi Yanagida
    ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2021年03月30日
    研究論文(学術雑誌)
  • Self-Anti-Stacking 2D Metal Phosphide Loop-Sheet Heterostructures by Edge-Topological Regulation for Highly Efficient Water Oxidation
    Quan Quan, Zhengxun Lai, Yan Bao, Xiuming Bu, You Meng, Wei Wang, Tsunaki Takahashi, Takuro Hosomi, Kazuki Nagashima, Takeshi Yanagida, Chuntai Liu, Jian Lu, Johnny C. Ho
    SMALL, 17, 7, WILEY-V C H VERLAG GMBH, 2021年02月
    英語, 研究論文(学術雑誌), 2D metal phosphide loop-sheet heterostructures are controllably synthesized by edge-topological regulation, where Ni2P nanosheets are edge-confined by the N-doped carbon loop, containing ultrafine NiFeP nanocrystals (denoted as NiFeP@NC/Ni2P). This loop-sheet feature with lifted-edges prevents the stacking of nanosheets and induces accessible open channels for catalytic site exposure and gas bubble release. Importantly, these NiFeP@NC/Ni2P hybrids exhibit a remarkable oxygen evolution activity with an overpotential of 223 mV at 20 mA cm(-2) and a Tafel slope of 46.1 mV dec(-1), constituting the record-high performance among reported metal phosphide electrocatalysts. The NiFeP@NC/Ni2P hybrids are also employed as both anode and cathode to achieve an alkaline electrolyzer for overall water splitting, delivering a current density of 10 mA cm(-2) with a voltage of 1.57 V, comparable to that of the commercial Pt/C||RuO2 couple (1.56 V). Moreover, a photovoltaic-electrolysis coupling system can as well be effectively established for robust overall water splitting. Evidently, this ingenious protocol would expand the toolbox for designing efficient 2D nanomaterials for practical applications.
  • Enhancement of pH Tolerance in Conductive Al-Doped ZnO Nanofilms via Sequential Annealing
    Ruolin Yan, Tsunaki Takahashi, Hao Zeng, Takuro Hosomi, Masaki Kanai, Guozhu Zhang, Kazuki Nagashima, Takeshi Yanagida
    ACS APPLIED ELECTRONIC MATERIALS, 3, 2, 955, 962, AMER CHEMICAL SOC, 2021年02月
    英語, 研究論文(学術雑誌), Chemically stable and electrically conductive metal oxide nanofilms are promising as robust electrodes for chemical/ biosensors and for photoelectrochemical applications, which require harsh conditions (e.g., acidic or basic environments). Among the various conductive metal oxides, impurity-doped ZnO nanofilms deposited on substrates are chemically nonresistive to acidic and basic environments because of the inevitable etching effects. Herein, we demonstrate a strategy to enhance the pH tolerance of Al-doped ZnO (AZO) nanofilms using a sequential annealing technique for film preparation. This technique involves first annealing in air followed by annealing in Zn vapor atmosphere. Although the as-grown AZO nanofilms rapidly dissolved in acidic and basic solutions, the sequentially annealed AZO nanofilms exhibited excellent pH tolerance toward the chemical etching rate and electrical resistance in buffer solutions, with pH ranging from 3 to 11. This enhancement effect of pH tolerance was considerably weakened when sequential annealing was performed in reverse (Zn vapor/air). The origin of the enhanced pH tolerance of the sequentially annealed AZO nanofilms is discussed in terms of the compensation of the anion/cation vacancies and the surface polarity of the ZnO(0001) surface.
  • ZnO/SiO2 core/shell nanowires for capturing CpG rich single-stranded DNAs.
    Marina Musa, Takao Yasui, Kazuki Nagashima, Masafumi Horiuchi, Zetao Zhu, Quanli Liu, Taisuke Shimada, Akihide Arima, Takeshi Yanagida, Yoshinobu Baba
    Analytical methods : advancing methods and applications, 13, 3, 337, 344, 2021年01月28日, [国際誌]
    英語, 研究論文(学術雑誌), Atomic layer deposition (ALD) is capable of providing an ultrathin layer on high-aspect ratio structures with good conformality and tunable film properties. In this research, we modified the surface of ZnO nanowires through ALD for the fabrication of a ZnO/SiO2 (core/shell) nanowire microfluidic device which we utilized for the capture of CpG-rich single-stranded DNAs (ssDNA). Structural changes of the nanowires while varying the number of ALD cycles were evaluated by statistical analysis and their relationship with the capture efficiency was investigated. We hypothesized that finding the optimum number of ALD cycles would be crucial to ensure adequate coating for successful tuning to the desired surface properties, besides promoting a sufficient trapping region with optimal spacing size for capturing the ssDNAs as the biomolecules traverse through the dispersed nanowires. Using the optimal condition, we achieved high capture efficiency of ssDNAs (86.7%) which showed good potential to be further extended for the analysis of CpG sites in cancer-related genes. This finding is beneficial to the future design of core/shell nanowires for capturing ssDNAs in biomedical applications.
  • ELECTRICAL DISCRIMINATIONS OF DRUG-RESISTANT BACTERIA VIA ANTIBIOTIC STIMULATION-ASSISTED MICROPORE SENSING
    Taisuke Shimada, Aomi Yoshikawa, Takao Yasui, Seiji Yamasaki, Kazuki Nagashima, Kunihiko Nishino, Takeshi Yanagida, Yoshinobu Baba
    MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences, 767, 768, 2021年
    研究論文(国際会議プロシーディングス), Evolutions of bacterial resistances are global health problems stemming from inappropriate uses of antibiotics without testing their effectiveness. Keeping their effectiveness is essential to combat bacterial infections, however, ideal uses are hampered by technical barriers like evaluation time. Herein, we propose a method for electrical discrimination of drug-resistance(s) within 1-2 hours by micropore-employed single bacteria sensing, presented on MicroTAS 2019 [1], combined with antibiotic-stimulations. 10 minutes for the stimulations allowed to discriminate single signals derived from susceptible and resistant strains with over 83.7% accuracy. Our method will contribute to rapidly detect bacteria with resistance(s), enabling to select proper antibiotics.
  • ANALYZING PARTICULATE MATTERS VIA SURFACTANT-ASSISTED MICROFLUIDIC IONIC CURRENT SENSING WITH MACHINE LEARNING-DRIVEN IDENTIFICATION
    Keiko Fujino, Taisuke Shimada, Takao Yasui, Kazuki Nagashima, Takashi Yanagida, Noritada Kaji, Yoshinobu Baba
    MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences, 1481, 1482, 2021年
    研究論文(国際会議プロシーディングス), Exposures to particulate matters (PMs) are one of important factors for human health, however, their risks are little known due to lacks of comprehensive sensing methods that can access their physicochemical properties. Here, we developed a microfluidics-based method to characterize size and compositions of PMs via combining surfactant-assisted single particle detection, presented on MicroTAS 2020 [1], with machine learning (ML)-driven identifications. Both of hydrophilic and hydrophobic particles were sensed and their electrical signals were discriminated with 98% accuracy at the single level. Our method will comprehensively sense real PMs to characterize their physicochemical properties, enabling to understand health risks.
  • Nanowire-based sensor electronics for chemical and biological applications
    Guozhu Zhang, Hao Zeng, Jiangyang Liu, Kazuki Nagashima, Tsunaki Takahashi, Takuro Hosomi, Wataru Tanaka, Takeshi Yanagida
    The Analyst, 146, 22, 6684, 6725, Royal Society of Chemistry ({RSC}), 2021年
    英語, 研究論文(学術雑誌), Detection and recognition of chemical and biological species via sensor electronics are important not only for various sensing applications but also for fundamental scientific understanding.
  • The impact of surface Cu2+ of ZnO/(Cu1−xZnx)O heterostructured nanowires on the adsorption and chemical transformation of carbonyl compounds
    Jiangyang Liu, Kazuki Nagashima, Yuki Nagamatsu, Takuro Hosomi, Hikaru Saito, Chen Wang, Wataru Mizukami, Guozhu Zhang, Benjarong Samransuksamer, Tsunaki Takahashi, Masaki Kanai, Takao Yasui, Yoshinobu Baba, Takeshi Yanagida
    Chemical Science, Royal Society of Chemistry (RSC), 2021年
    研究論文(学術雑誌),

    Unexpected features of surface Cu2+ on ZnO/(Cu1−xZnx)O nanowires for molecular transformation and electrical sensing of carbonyl compounds were found.

  • A thermally robust and strongly oxidizing surface of WO3 hydrate nanowires for electrical aldehyde sensing with long-term stability
    Guozhu Zhang, Takuro Hosomi, Wataru Mizukami, Jiangyang Liu, Kazuki Nagashima, Tsunaki Takahashi, Masaki Kanai, Takeharu Sugiyama, Takao Yasui, Yuriko Aoki, Yoshinobu Baba, Johnny C. Ho, Takeshi Yanagida
    Journal of Materials Chemistry A, 9, 9, 5815, 5824, Royal Society of Chemistry (RSC), 2021年
    研究論文(学術雑誌),

    Thermally robust and strongly oxidizing surface is created by a simple strong acid treatment on WO3 hydrate nanowires, which enables integrated nanosensors to operate with a superior sensing performance to aldehyde molecules with long-term stability.

  • Oxygen-Induced Reversible Sn-Dopant Deactivation between Indium Tin Oxide and Single-Crystalline Oxide Nanowire Leading to Interfacial Switching
    Hao Zeng, Tsunaki Takahashi, Takehito Seki, Masaki Kanai, Guozhu Zhang, Takuro Hosomi, Kazuki Nagashima, Naoya Shibata, Takeshi Yanagida
    ACS Applied Materials & Interfaces, 12, 47, 52929, 52936, American Chemical Society (ACS), 2020年11月25日
    研究論文(学術雑誌)
  • Artificial visual systems enabled by quasi-two-dimensional electron gases in oxide superlattice nanowires
    You Meng, Fangzhou Li, Changyong Lan, Xiuming Bu, Xiaolin Kang, Renjie Wei, SenPo Yip, Dapan Li, Fei Wang, Tsunaki Takahashi, Takuro Hosomi, Kazuki Nagashima, Takeshi Yanagida, Johnny C. Ho
    SCIENCE ADVANCES, 6, 46, AMER ASSOC ADVANCEMENT SCIENCE, 2020年11月
    英語, 研究論文(学術雑誌), Rapid development of artificial intelligence techniques ignites the emerging demand on accurate perception and understanding of optical signals from external environments via brain-like visual systems. Here, enabled by quasi-two-dimensional electron gases (quasi-2DEGs) in InGaO3(ZnO)(3) superlattice nanowires (NWs), an artificial visual system was built to mimic the human ones. This system is based on an unreported device concept combining coexistence of oxygen adsorption-desorption kinetics on NW surface and strong carrier quantum-confinement effects in superlattice core, to resemble the biological Ca2+ ion flux and neurotransmitter release dynamics. Given outstanding mobility and sensitivity of superlattice NWs, an ultralow energy consumption down to subfemtojoule per synaptic event is realized in quasi-2DEG synapses, which rivals that of biological synapses and now available synapse-inspired electronics. A flexible quasi-2DEG artificial visual system is demonstrated to simultaneously perform high-performance light detection, brain-like information processing, nonvolatile charge retention, in situ multibit-level memory, orientation selectivity, and image memorizing.
  • Face-Selective Crystal Growth of Hydrothermal Tungsten Oxide Nanowires for Sensing Volatile Molecules
    Sho Nekita, Kazuki Nagashima, Guozhu Zhang, Qianli Wang, Masaki Kanai, Tsunaki Takahashi, Takuro Hosomi, Kentaro Nakamura, Tetsuya Okuyama, Takeshi Yanagida
    ACS Applied Nano Materials, 3, 10, 10252, 10260, American Chemical Society (ACS), 2020年10月23日
    研究論文(学術雑誌)
  • Facile Synthesis of Zinc Titanate Nanotubes via Reaction-byproduct Etching
    Jiangyang Liu, Kazuki Nagashima, Hideto Yoshida, Takuro Hosomi, Tsunaki Takahashi, Guozhu Zhang, Masaki Kanai, Yong He, Takeshi Yanagida
    Chemistry Letters, 49, 10, 1220, 1223, The Chemical Society of Japan, 2020年10月05日
    研究論文(学術雑誌)
  • Perovskite Core-Shell Nanowire Transistors: Interfacial Transfer Doping and Surface Passivation
    You Meng, Zhengxun Lai, Fangzhou Li, Wei Wang, Senpo Yip, Quan Quan, Xiuming Bu, Fei Wang, Yan Bao, Takuro Hosomi, Tsunaki Takahashi, Kazuki Nagashima, Takeshi Yanagida, Jian Lu, Johnny C. Ho
    ACS NANO, 14, 10, 12749, 12760, AMER CHEMICAL SOC, 2020年10月
    英語, 研究論文(学術雑誌), While halide perovskite electronics are rapidly developing, they are greatly limited by the inferior charge transport and poor stability. In this work, effective surface charge transfer doping of vapor-liquid-solid (VLS)-grown single-crystalline cesium lead bromide perovskite (CsPbBr3) nanowires (NWs) via molybdenum trioxide (MoO3) surface functionalization is achieved. Once fabricated into NW devices, due to the efficient interfacial charge transfer and reduced impurity scattering, a 15x increase in the field-effect hole mobility (mu(h)) from 1.5 to 23.3 cm(2)/(V s) is accomplished after depositing the 10 nm thick MoO3 shell. This enhanced mobility is already better than any mobility value reported for perovskite field-effect transistors (FETs) to date. The photodetection performance of these CsPbBr3/MoO3 core-shell NWs is also investigated to yield a superior responsivity (R) up to 2.36 x 10(3) A/W and an external quantum efficiency (EQE) of over 5.48 x 10(5)% toward the 532 nm regime. Importantly, the MoO3 shell can provide excellent surface passivation to the CsPbBr3 NW core that minimizes the diffusion of detrimental water and oxygen molecules, improving the air stability of CsPbBr3/MoO3 coreshell NW devices. All these findings evidently demonstrate the surface doping as an enabling technology to realize high-mobility and air-stable low-dimensional halide perovskite devices.
  • Phosphonic Acid Modified ZnO Nanowire Sensors: Directing Reaction Pathway of Volatile Carbonyl Compounds
    Chen Wang, Takuro Hosomi, Kazuki Nagashima, Tsunaki Takahashi, Guozhu Zhang, Masaki Kanai, Hideto Yoshida, Takeshi Yanagida
    ACS Applied Materials & Interfaces, 12, 39, 44265, 44272, American Chemical Society (ACS), 2020年09月30日
    研究論文(学術雑誌)
  • Ammonia-Induced Seed Layer Transformations in a Hydrothermal Growth Process of Zinc Oxide Nanowires
    Quanli Liu, Takao Yasui, Kazuki Nagashima, Takeshi Yanagida, Mitsuo Hara, Masafumi Horiuchi, Zetao Zhu, Hiromi Takahashi, Taisuke Shimada, Akihide Arima, Yoshinobu Baba
    The Journal of Physical Chemistry C, 124, 37, 20563, 20568, American Chemical Society (ACS), 2020年09月17日
    研究論文(学術雑誌)
  • アンサンブル分子センシングによる堅牢な呼気診断法の開発
    長島 一樹, Jirayupat Chaiyanut, 細見 拓郎, 高橋 綱己, Zhang Guozhu, 金井 真樹, 柳田 剛
    応用物理学会学術講演会講演予稿集, 2020.2, 115, 115, 公益社団法人 応用物理学会, 2020年08月26日
    日本語
  • 堅牢なナノ界面と分子認識エレクトロニクス
    長島 一樹, 高橋 綱己, 細見 拓郎, 柳田 剛
    応用物理学会学術講演会講演予稿集, 2020.2, 59, 59, 公益社団法人 応用物理学会, 2020年08月26日
    日本語
  • Face-selective tungstate ions drive zinc oxide nanowire growth direction and dopant incorporation
    Jiangyang Liu, Kazuki Nagashima, Hiroki Yamashita, Wataru Mizukami, Jun Uzuhashi, Takuro Hosomi, Masaki Kanai, Xixi Zhao, Yoshinori Miura, Guozhu Zhang, Tsunaki Takahashi, Masaru Suzuki, Daiki Sakai, Benjarong Samransuksamer, Yong He, Tadakatsu Ohkubo, Takao Yasui, Yuriko Aoki, Johnny C. Ho, Yoshinobu Baba, Takeshi Yanagida
    COMMUNICATIONS MATERIALS, 1, 1, SPRINGERNATURE, 2020年08月
    英語, 研究論文(学術雑誌), Tailoring the elemental doping of inorganic nanowires remains an important challenge due to complex dopant incorporation pathways. Here we report that the face-selectivity of tungstate ions controls growth direction and dopant incorporation of hydrothermal zinc oxide nanowires. The introduction of tungstate ions on nanowire surface during synthesis unexpectedly enhances nucleation at sidewall 1010 planes, while dopant incorporation occurs only on (0001) planes. This conflicting face-selective behavior leads to inhomogeneous dopant distribution. Density functional theory calculations reveal that the face-selective behavior can be interpreted in terms of the effect of coordination structure of the tungstate ions on each zinc oxide crystal plane. In addition, we demonstrate a rational strategy to control the morphology and the elemental doping of tungsten-doped zinc oxide nanowires. Controlling the growth processes of nanowires is vital for tailoring their properties. Here, the presence of tungstate ions on specific surface planes of zinc oxide nanowires causes nanowire growth and chemical doping along specific crystal planes.
  • Unusual Sequential Annealing Effect in Achieving High Thermal Stability of Conductive Al-Doped ZnO Nanofilms
    Ruolin Yan, Tsunaki Takahashi, Masaki Kanai, Takuro Hosomi, Guozhu Zhang, Kazuki Nagashima, Takeshi Yanagida
    ACS APPLIED ELECTRONIC MATERIALS, 2, 7, 2064, 2070, AMER CHEMICAL SOC, 2020年07月
    英語, 研究論文(学術雑誌), Emerging interactive sensor electronics requires metal oxide V electrodes that possess long-term atmospheric stability and electrical conductivity to function under harsh conditions (e.g., high temperatures in air. In this study, we report a rational method to accomplish the long-term thermal stability of conductive AI-doped ZnO (AZO) nanofilms, which have been thermally unstable due to inevitable crystal defects. Our method utilizes a sequential thermal annealing in air and Zn vapor atmosphere. An initial annealing was performed in air, followed by a second annealing in a Zn vapor atmosphere. Air tolerance tests on the resulting AZO nanofilms revealed the stable electrical resistivity (similar to 10(-4) Omega.cm) in air, even at temperatures up to 500 degrees C. Conversely, when annealing was performed in the reverse sequence, the electrical resistivity of the AZO nanofilms significantly increased by 5 orders of magnitude during tolerance tests. Photoluminescence data further supported the results of the air tolerance tests. The unusual effect of the annealing-atmosphere sequence is discussed in terms of the presence of dual anion/cation vacancies and the sequential benefits when these vacancies are compensated during annealing. The applicability of these thermally stable AZO electrodes for use in nanochannel sensor devices is demonstrated. Furthermore, we show that the proposed sequential annealing method is applicable for Ga-doped ZnO films, supporting its use as a platform fabrication method. Thus, the proposed fundamental concept for tailoring thermally stable conductive metal oxide electrodes provides a foundation for designing interactive electronic devices that are stable for a long period.
  • Mechanical Rupture-Based Antibacterial and Cell-Compatible ZnO/SiO2 Nanowire Structures Formed by Bottom-Up Approaches.
    Taisuke Shimada, Takao Yasui, Akihiro Yonese, Takeshi Yanagida, Noritada Kaji, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    Micromachines, 11, 6, 2020年06月24日, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), There are growing interests in mechanical rupture-based antibacterial surfaces with nanostructures that have little toxicity to cells around the surfaces; however, current surfaces are fabricated via top-down nanotechnologies, which presents difficulties to apply for bio-surfaces with hierarchal three-dimensional structures. Herein, we developed ZnO/SiO2 nanowire structures by using bottom-up approaches and demonstrated to show mechanical rupture-based antibacterial activity and compatibility with human cells. When Escherichia coli were cultured on the surface for 24 h, over 99% of the bacteria were inactivated, while more than 80% of HeLa cells that were cultured on the surface for 24 h were still alive. This is the first demonstration of mechanical rupture-based bacterial rupture via the hydrothermally synthesized nanowire structures with antibacterial activity and cell compatibility.
  • Monovalent sulfur oxoanions enable millimeter-long single-crystalline h-WO3 nanowire synthesis.
    Guozhu Zhang, Chen Wang, Wataru Mizukami, Takuro Hosomi, Kazuki Nagashima, Hideto Yoshida, Kentaro Nakamura, Tsunaki Takahashi, Masaki Kanai, Takao Yasui, Yuriko Aoki, Yoshinobu Baba, Takeshi Yanagida
    Nanoscale, 12, 16, 9058, 9066, 2020年04月28日, [査読有り], [国際誌]
    英語, 研究論文(学術雑誌), Here, we discuss a misunderstanding regarding chemical capping, which has intrinsically hindered the extension of the length of hexagonal (h)-WO3 nanowires in previous studies. Although divalent sulfate ions (SO42-) have been strongly believed to be efficient capping ions for directing anisotropic h-WO3 nanowire growth, we have found that the presence of SO42- is highly detrimental to the anisotropic crystal growth of the h-WO3 nanowires, and a monovalent sulfur oxoanion (HSO4-) rather than SO42- only substantially promotes the anisotropic h-WO3 nanowire growth. Ab initio electronic structure simulations revealed that the monovalent sulfur oxoanions were preferentially able to cap the sidewall plane (100) of the h-WO3 nanowires due to the lower hydration energy when compared with SO42-. Based on this capping strategy, using the monovalent sulfur oxoanion (CH3SO3-), which cannot generate divalent sulfur oxoanions, we have successfully fabricated ultra-long h-WO3 nanowires up to the millimeter range (1.2 mm) for a wider range of precursor concentrations. We have demonstrated the feasibility of these millimeter-long h-WO3 nanowires for the electrical sensing of molecules (lung cancer biomarker: nonanal) on flexible substrates, which can be operated at room temperature with mechanical flexibility with bending cycles up to 104 times due to the enhanced textile effect.
  • Photolithographically Constructed Single ZnO Nanowire Device and Its Ultraviolet Photoresponse.
    Quanli Liu, Takao Yasui, Kazuki Nagashima, Takeshi Yanagida, Masafumi Horiuchi, Zetao Zhu, Hiromi Takahashi, Taisuke Shimada, Akihide Arima, Yoshinobu Baba
    Analytical sciences : the international journal of the Japan Society for Analytical Chemistry, 36, 9, 1125, 1129, 2020年04月17日, [査読有り], [国内誌]
    英語, 研究論文(学術雑誌), A sparse ZnO nanowire array with aspect ratio of ca. 120 and growth rate of 1 μm/h was synthesized by controlling the density of seeds at the initial stage of nanowire growth. The spatially-separated nanowires were cut off from the growth substrate without breaking, and thus were useful in the construction of a single-nanowire device by photolithography. The device exhibited a linear current-voltage characteristic associated with ohmic contact between ZnO nanowire and electrodes. The device further demonstrated a reliable photoresponse with an IUV/Idark of ∼100 to ultraviolet light irradiation.
  • Analysis of particulate matters via surfactant-assisted ionic current sensing
    Keiko Fujino, Taisuke Shimada, Takao Yasui, Kazuki Nagashima, Takashi Yanagida, Noritada Kaji, Yoshinobu Baba
    MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences, 498, 499, 2020年
    研究論文(国際会議プロシーディングス), © 2020 CBMS-0001 Toward tracking lifelong exposure history of particulate matters (PMs) for understanding its disease risk, we realized a surfactant-assisted ionic current sensing for analyzing the size and concentration of hydrophobic PMs. Previously, we reported a PM sensor via water film-based collection and micropore-employed ionic current sensing at MicroTAS 2018 [1]. However, an analysis on PM number concentration has not achieved due to a difficulty in sensing hydrophobic PMs. Here, the hydrophobic PMs were detected with the aid of sodium dodecyl sulfate (SDS) and information on PM size and number concentration was obtained.
  • Growth Kinetics and Magnetic Property of Single-Crystal Fe Nanowires Grown via Vapor-Solid Mechanism Using Chemically Synthesized FeO Nanoparticle Catalysts
    Takashi Yanase, Uika Ogihara, Yoshihiro Awashima, Takeshi Yanagida, Kazuki Nagashima, Taro Nagahama, Toshihiro Shimada
    CRYSTAL GROWTH & DESIGN, 19, 12, 7257, 7263, AMER CHEMICAL SOC, 2019年12月, [査読有り]
    英語, 研究論文(学術雑誌), Single-crystal Fe nanowires (NWs) were synthesized on SiO2/Si substrates by chemical vapor deposition (CVD) using a two-flow system in the presence of FeO nanoparticles as catalysts. Transmission electron microscopy observations and an electron diffraction analysis revealed that the NW was defect-free alpha-Fe (bcc structure) oriented in the < 100 > direction. A plausible mechanism of the Fe NW growth is suggested based on the observations of the morphology and characteristic diameter of the Fe NW. We found that the NWs became polycrystalline when their diameter was approximately 100 nm. The excellent crystal quality of the single-crystal NW was confirmed by electron diffraction and the residual resistance ratio. Magnetic uniformity and a strong shape-anisotropic behavior of magnetization were observed by measuring the hysteresis loop and the angle dependence of the magneto-optical Kerr effect, respectively.
  • Controlling Bi Provoked Nanostructure Formation in GaAs/GaAsBi Core–Shell Nanowires
    Teruyoshi Matsuda, Kyohei Takada, Kosuke Yano, Rikuo Tsutsumi, Kohei Yoshikawa, Satoshi Shimomura, Yumiko Shimizu, Kazuki Nagashima, Takeshi Yanagida, Fumitaro Ishikawa
    Nano Letters, 19, 12, 8510, 8518, AMER CHEMICAL SOC, 2019年12月, [査読有り]
    英語, 研究論文(学術雑誌), We control the formation of Bi-induced nanostructures on the growth of GaAs/GaAsBi core-shell nanowires (NWs). Bi serves as not only a constituent but also a surfactant and nanowire growth catalyst. Thus, we paved a way to achieve unexplored III-V nanostructures employing the characteristic supersaturation of catalyst droplets, structural modifications induced by strain, and incorporation into the host GaAs matrix correlated with crystalline defects and orientations. When Ga is deficient during growth, Bi accumulates on the vertex of core GaAs NWs and serves as a nanowire growth catalyst for the branched structures to azimuthal < 112 >. We find a strong correlation between Bi accumulation and stacking faults. Furthermore, Bi is preferentially incorporated on the GaAs (112)B surface, leading to spatially selective Bi incorporation into a confined area that has a Bi concentration of over 7%. The obtained GaAs/GaAsBi/GaAs heterostructure with an interface defined by the crystalline twin defects in a zinc-blende structure can be potentially applied to a quantum confined structure. Our finding provides a rational design concept for the creation of GaAsBi based nanostructures and the control of Bi incorporation beyond the fundamental limit.
  • Substantial Narrowing on the Width of “Concentration Window” of Hydrothermal ZnO Nanowires via Ammonia Addition
    Daiki Sakai, Kazuki Nagashima, Hideto Yoshida, Masaki Kanai, Yong He, Guozhu Zhang, Xixi Zhao, Tsunaki Takahashi, Takao Yasui, Takuro Hosomi, Yuki Uchida, Seiji Takeda, Yoshinobu Baba, Takeshi Yanagida
    Scientific Reports, 9, 1, 14160, 14160, 2019年12月01日, [国際誌]
    英語, 研究論文(学術雑誌), © 2019, The Author(s). A crystal growth of hydrothermal ZnO nanowires essentially requires a concentration control within so-called “concentration window”, where the anisotropic crystal growth of ZnO nanowires preferentially occurs. Although understanding what exactly determines the width of “concentration window” is important to tailor the anisotropic crystal growth process, the fundamental knowledge as to “concentration window” is still scarce. Here we report the effect of ammonia addition on the width of “concentration window” using conventional hydrothermal ZnO nanowire growth. We found that the ammonia addition substantially narrows the width of “concentration window”. Within the narrow range of zinc complex concentration, we found a significant increase of growth rate (up to 2000 nm/h) of ZnO nanowires. The narrowed “concentration window” and the resultant increased growth rate by the ammonia addition can be understood in terms of synchronized effects of both (1) a reduction of zinc hydroxide complex (precursor) concentration and (2) a fast rate limiting process of ligand exchange between different zinc complexes. Thus, the present knowldege as to “concentration window” will accelerate further tailoring an anisotropic crystal growth of hydrothermal ZnO nanowires.
  • Water–Organic Cosolvent Effect on Nucleation of Solution-Synthesized ZnO Nanowires
    Yuya Akihiro, Kazuki Nagashima, Takuro Hosomi, Masaki Kanai, Hiroshi Anzai, Tsunaki Takahashi, Guozhu Zhang, Takao Yasui, Yoshinobu Baba, Takeshi Yanagida
    ACS Omega, 4, 5, 8299, 8304, 2019年05月08日, [査読有り]
    英語, 研究論文(学術雑誌), © 2019 American Chemical Society. Here, we show the effect of water-organic (acetone, tert-butyl alcohol, and isopropanol) cosolvents on nucleation and anisotropic crystal growth of solution-synthesized ZnO nanowires. The addition of organic solution does not alter the face-selective crystal growth nature but significantly promotes the crystal growth of both length and diameter of the nanowires. Systematic investigations reveal that a variation of the relative dielectric constant in the cosolvent can rigorously explain the observed effect of the water-organic cosolvent on the ZnO nanowire growth via the degree of supersaturation for the nucleation. The difference between acetone, tert-butyl alcohol, and isopropanol on the cosolvent effect can be interpreted in terms of a local solvent-sorting effect.
  • Discrimination of VOCs molecules via extracting concealed features from a temperature-modulated p-type NiO sensor               
    Hongyu Liu, Yuhui He, Kazuki Nagashima, Gang Meng, Tiantian Dai, Bin Tong, Zanhong Deng, Shimao Wang, Nengwei Zhu, Takeshi Yanagida, Xiaodong Fang
    Sensors and Actuators B: Chemical, 293, 342, 349, 2019年04月, [査読有り]
    英語, 研究論文(学術雑誌)
  • Paper-Based Disposable Molecular Sensor Constructed from Oxide Nanowires, Cellulose Nanofibers, and Pencil-Drawn Electrodes
    Hirotaka Koga, Kazuki Nagashima, Yintong Huang, Guozhu Zhang, Chen Wang, Tsunaki Takahashi, Akihide Inoue, Hong Yan, Masaki Kanai, Yong He, Kojiro Uetani, Masaya Nogi, Takeshi Yanagida
    ACS Applied Materials and Interfaces, 11, 16, 15044, 15050, 2019年04月, [査読有り]
    英語, 研究論文(学術雑誌), © 2019 American Chemical Society. Progress toward the concept of "a trillion sensor universe" requires sensor devices to become more abundant, ubiquitous, and be potentially disposable. Here, we report a paper-based disposable molecular sensor device constructed from a nanowire sensor based on common zinc oxide (ZnO), a wood-derived biodegradable cellulose nanofiber paper substrate, and a low-cost graphite electrode. The ZnO nanowire/cellulose nanofiber composite structure is embedded in the surface of the cellulose nanofiber paper substrate via a two-step papermaking process. This structure provides a mechanically robust and efficiently bridged network for the nanowire sensor, while ensuring efficient access to target molecules and allowing reliable electrical contact with electrodes. The as-fabricated paper sensor device with pencil-drawn graphite electrodes exhibits efficient resistance change-based molecular sensing of NO 2 as a model gas. The performance of our device is comparable to that of noble metal electrodes. Furthermore, we demonstrate cut-and-paste usability and easy disposal of the sensor device with its uniform in-plane sensing properties. Our strategy offers a disposable molecular sensing platform for use in future sensor network technologies.
  • Unusual Oxygen Partial Pressure Dependence of Electrical Transport of Single-Crystalline Metal Oxide Nanowires Grown by the Vapor–Liquid–Solid Process
    Hiroshi Anzai, Tsunaki Takahashi, Masaru Suzuki, Masaki Kanai, Guozhu Zhang, Takuro Hosomi, Takehito Seki, Kazuki Nagashima, Naoya Shibata, Takeshi Yanagida
    Nano Letters, 19, 3, 1675, 1681, 2019年03月13日, [査読有り]
    英語, 研究論文(学術雑誌), © 2019 American Chemical Society. In general, the electrical conductivities of n-type semiconducting metal oxide nanostructures increase with the decrease in the oxygen partial pressure during crystal growth owing to the increased number of crystal imperfections including oxygen vacancies. In this paper, we report an unusual oxygen partial pressure dependence of the electrical conductivity of single-crystalline SnO 2 nanowires grown by a vapor-liquid-solid (VLS) process. The electrical conductivity of a single SnO 2 nanowire, measured using the four-probe method, substantially decreases by 2 orders of magnitude when the oxygen partial pressure for the crystal growth is reduced from 10 -3 to 10 -4 Pa. This contradicts the conventional trend of n-type SnO 2 semiconductors. Spatially resolved single-nanowire electrical transport measurements, microstructure analysis, plane-view electron energy-loss spectroscopy, and molecular dynamics simulations reveal that the observed unusual oxygen partial pressure dependence of the electrical transport is attributed to the intrinsic differences between the two crystal growth interfaces (LS and VS interfaces) in the critical nucleation of the crystal growth and impurity incorporation probability as a function of the oxygen partial pressure. The impurity incorporation probability at the LS interface is always lower than that at the VS interface, even under reduced oxygen partial pressures.
  • Rational Method of Monitoring Molecular Transformations on Metal-Oxide Nanowire Surfaces               
    Chen Wang, Takuro Hosomi, Kazuki Nagashima, Tsunaki Takahashi, Guozhu Zhang, Masaki Kanai, Hao Zeng, Wataru Mizukami, Nobutaka Shioya, Takafumi Shimoaka, Takehiro Tamaoka, Hideto Yoshida, Seiji Takeda, Takao Yasui, Yoshinobu Baba, Yuriko Aoki, Jun Terao, Takeshi Hasegawa, Takeshi Yanagida
    Nano Letters, 19, 4, 2443, 2449, 2019年03月, [査読有り]
    英語, 研究論文(学術雑誌)
  • VLS 結晶成長界面に基づいたSb-SnO2ナノワイヤの電気伝導度制御
    Zetao Zhu, 高橋 綱己, 細見 拓郎, 長島 一樹, 金井 真樹, 柳田 剛
    応用物理学会学術講演会講演予稿集, 2019.1, 1317, 1317, 公益社団法人 応用物理学会, 2019年02月25日
    日本語
  • 単結晶金属酸化物ナノワイヤ結晶成長の設計指針
    長島 一樹, 高橋 綱己, 細見 拓郎, 柳田 剛
    日本結晶成長学会誌, 46, 2, n/a, 日本結晶成長学会, 2019年, [査読有り]
    日本語, Single crystalline metal oxide nanowires have demonstrated a great promise for IoT sensors, biomedical and environment-analytical devices because of their thermal/chemical robustness in air and water conditions. This report introduces a rational concept for designing the single crystalline metal oxide nanowires. The anisotropic nanowire growth can be achieved by rigorously controlling a material supply flux or a precursor concentration within an appropriate range, so-called “flux/concentration window”. The flux/concentration window is determined by the competitive nucleation events at different crystal growth interfaces. Recent our study shows the critical importance of the flux/concentration window to control not only the nanowire structure, but also their composition, crystal phase and functional properties.
  • Discriminating drug-resistant bacteria using AI analysis on fine current changes from inner ION leakages
    Aomi Yoshikawa, Takao Yasui, Taisuke Shimada, Seiji Yamasaki, Kunihiko Nishino, Takeshi Yanagida, Kazuki Nagashima, Takashi Washio, Tomoji Kawai, Yoshinobu Baba
    23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019, 852, 853, 2019年
    研究論文(国際会議プロシーディングス), © 2019 CBMS-0001. As the WHO delivers a strong warning about drug-resistant bacteria, their types are increasing along with improper use of antibiotic drugs by medical professions, due to the fact that conventional methods cannot identify drug-resistant bacteria in a short time, and show a guideline for proper use of antibiotic drugs rapidly. Herein, we demonstrated a rational methodology for drug-resistant bacteria identification via machine learning analysis on fine current changes from bacteria inner ion leakages, which given by highly applied electric fields in microchannels We believe that our methodology opens up a new way for proper use of antibiotic drugs against drug-resistant bacteria.
  • Electrical conductivity and optical bandgap of carbonized cellulose nanofiber papers               
    D. Fukushima, K. Nagashima, T. Takahashi, T. Yanagida, Y. Nishina, K. Uetani, M. Nogi, H. Koga
    2019年01月
    英語
  • Synthesis of Monodispersedly Sized ZnO Nanowires from Randomly Sized Seeds
    Xixi Zhao, Kazuki Nagashima, Guozhu Zhang, Takuro Hosomi, Hideto Yoshida, Yuya Akihiro, Masaki Kanai, Wataru Mizukami, Zetao Zhu, Tsunaki Takahashi, Masaru Suzuki, Benjarong Samransuksamer, Gang Meng, Takao Yasui, Yuriko Aoki, Yoshinobu Baba, Takeshi Yanagida
    Nano Letters, 20, 1, 599, 605, 2019年, [国際誌]
    英語, 研究論文(学術雑誌), © 2019 American Chemical Society. We demonstrate the facile, rational synthesis of monodispersedly sized zinc oxide (ZnO) nanowires from randomly sized seeds by hydrothermal growth. Uniformly shaped nanowire tips constructed in ammonia-dominated alkaline conditions serve as a foundation for the subsequent formation of the monodisperse nanowires. By precisely controlling the sharp tip formation and the nucleation, our method substantially narrows the distribution of ZnO nanowire diameters from σ = 13.5 nm down to σ = 1.3 nm and controls their diameter by a completely bottom-up method, even initiating from randomly sized seeds. The proposed concept of sharp tip based monodisperse nanowires growth can be applied to the growth of diverse metal oxide nanowires and thus paves the way for bottom-up grown metal oxide nanowires-integrated nanodevices with a reliable performance.
  • Redox-Inactive CO2 Determines Atmospheric Stability of Electrical Properties of ZnO Nanowire Devices through a Roomerature Surface Reaction
    Kentaro Nakamura, Tsunaki Takahashi, Takuro Hosomi, Takehito Seki, Masaki Kanai, Guozhu Zhang, Kazuki Nagashima, Naoya Shibata, Takeshi Yanagida
    ACS Applied Materials and Interfaces, 11, 43, 40260, 40266, 2019年, [査読有り]
    研究論文(学術雑誌), Copyright © 2019 American Chemical Society. Emerging interactive electronics for the Internet of Things era inherently require the long-term stability of semiconductor devices exposed to air. Nanostructured metal oxides are promising options for such atmospherically stable semiconductor devices owing to their inherent stability in air. Among various oxide nanostructures, ZnO nanowires have been the most intensively studied for electrical and optical device applications. Here, we demonstrate a strategy for achieving the atmospheric electrical stability of ZnO nanowire devices. Although the chemically active oxygen and water in air are strong candidates for affecting the electrical stability of nanoscale metal oxides, we found that the ppm-level redox-inactive CO2 in air critically determines the atmospheric electrical stability of hydrothermally grown single-crystalline ZnO nanowires. A series of analyses using atmosphere-controlled electrical characterization of single nanowire devices, Fourier transform infrared spectroscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy consistently revealed that atmospheric CO2 reacts substantially with the ZnO nanowire surfaces, even at room temperature, to form an electrically insulative zinc carbonate thin layer. The formation of this layer essentially limits the atmospheric electrical stability of the ZnO nanowire devices. Based on this surface carbonation mechanism, we propose a strategy to suppress the detrimental surface reaction, which is based on (1) reducing the density of surface hydroxyl groups and (2) improving the nanowire crystallinity by thermal pretreatment. This approach improves the atmospheric electrical stability to at least 40 days in air.
  • Engineering Nanowire-Mediated Cell Lysis for Microbial Cell Identification
    Takao Yasui, Takeshi Yanagida, Taisuke Shimada, Kohei Otsuka, Masaki Takeuchi, Kazuki Nagashima, Sakon Rahong, Toyohiro Naito, Daiki Takeshita, Akihiro Yonese, Ryo Magofuku, Zetao Zhu, Noritada Kaji, Masaki Kanai, Tomoji Kawai, Yoshinobu Baba
    ACS Nano, 13, 2, 2262, 2273, 2019年, [査読有り]
    英語, 研究論文(学術雑誌), © 2019 American Chemical Society. Researchers have demonstrated great promise for inorganic nanowire use in analyzing cells or intracellular components. Although a stealth effect of nanowires toward cell surfaces allows preservation of the living intact cells when analyzing cells, as a completely opposite approach, the applicability to analyze intracellular components through disrupting cells is also central to understanding cellular information. However, the reported lysis strategy is insufficient for microbial cell lysis due to the cell robustness and wrong approach taken so far (i.e., nanowire penetration into a cell membrane). Here we propose a nanowire-mediated lysis method for microbial cells by introducing the rupture approach initiated by cell membrane stretching; in other words, the nanowires do not penetrate the membrane, but rather they break the membrane between the nanowires. Entangling cells with the bacteria-compatible and flexible nanowires and membrane stretching of the entangled cells, induced by the shear force, play important roles for the nanowire-mediated lysis to Gram-positive and Gram-negative bacteria and yeast cells. Additionally, the nanowire-mediated lysis is readily compatible with the loop-mediated isothermal amplification (LAMP) method because the lysis is triggered by simply introducing the microbial cells. We show that an integration of the nanowire-mediated lysis with LAMP provides a means for a simple, rapid, one-step identification assay (just introducing a premixed solution into a device), resulting in visual chromatic identification of microbial cells. This approach allows researchers to develop a microfluidic analytical platform not only for microbial cell identification including drug- and heat-resistance cells but also for on-site detection without any contamination.
  • ZnOナノワイヤ上に吸着した長鎖アルデヒドの化学反応挙動の解明
    王 琛, 細見 拓郎, 長島 一樹, 高橋 綱己, 張 国柱, 金井 真樹, 柳田 剛
    応用物理学会学術講演会講演予稿集, 2018.2, 1912, 1912, 公益社団法人 応用物理学会, 2018年09月05日
    日本語
  • 酸化物VLS結晶成長における空間均一な不純物ドーピングの設計指針
    Zhu Zetao, 高橋 綱己, 細見 拓郎, 長島 一樹, 柳田 剛
    応用物理学会学術講演会講演予稿集, 2018.2, 1908, 1908, 公益社団法人 応用物理学会, 2018年09月05日
    日本語
  • Thermal conductivity of Si nanowires with δ-modulated dopant distribution by self-heated 3ω method and its length dependence               
    Fuwei Zhuge, Tsunaki Takahashi, Masaki Kanai, Kazuki Nagashima, Naoki Fukata, Ken Uchida, Takeshi Yanagida
    Journal of Applied Physics, 124, 065105, 2018年08月, [査読有り]
    英語, 研究論文(学術雑誌)
  • A real-time simultaneous measurement on a microfluidic device for individual bacteria discrimination               
    Hirotoshi Yasaki, Takao Yasui, Takeshi Yanagida, Noritada Kaji, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    Sensors and Actuators B: Chemical, 260, 746, 752, 2018年03月, [査読有り]
    英語, 研究論文(学術雑誌)
  • Robust Ionic Current Sensor for Bacterial Cell Size Detection               
    Hirotoshi Yasaki, Taisuke Shimada, Takao Yasui, Takeshi Yanagida, Noritada Kaji, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    ACS Sensors, 33, 574, 579, 2018年02月, [査読有り]
    英語, 研究論文(学術雑誌)
  • PM2.5 analysis in liquid phase via water film-based collection and microfluidics-based electrical detection
    Taisuke Shimada, Hirotoshi Yasaki, Takao Yasui, Akihide Hibara, Takeshi Yanagida, Noritada Kaji, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018, 1, 270, 271, 2018年, [査読有り]
    研究論文(国際会議プロシーディングス), Copyright© (2018) by Chemical and Biological Microsystems Society.All rights reserved. Toward evaluation of health risk of particulate matter with size less than or equal to 2.5 µm (PM2.5), we propose a methodology for realizing the PM2.5 analysis in liquid phase via water film-based collection and microfluidics-based electrical detection. A hydrophilic nanowire surface was utilized in the collection for forming a water film, which enabled continuous collection of air-floating PM2.5 into liquid phase and followed-by detection. The collected PM2.5 was electrically detected and analyzed via ionic current sensing with a micropore. We believe proposed PM2.5 analysis methodology in liquid phase would allow to realize health risk evaluation and reduce health damage.
  • Selective molecular recognition using molecular fingerprinted nanowires
    Masafumi Horiuchi, Takao Yasui, Kazuki Nagashima, Takeshi Yanagida, Yoshinobu Baba
    22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018, 2, 659, 660, 2018年, [査読有り]
    研究論文(国際会議プロシーディングス), Copyright © (2018) by Chemical and Biological Microsystems Society. All rights reserved. Molecular recognition methods such as those found in antigen-antibody reactions are attracting attention. We demonstrated more selective molecular recognition through focusing on not only intermolecular interaction but also the shape of the molecules. Here, we fabricated molecular shapes of aniline on the titanium oxide thin film on the core-shell structure of zinc oxide/titanium oxide nanowires, and recognized aniline, selectively, using the aniline molecular shaped nanowires.
  • PM 2.5 Particle detection in a microfluidic device by using ionic current sensing
    Taisuke Shimada, Hirotoshi Yasaki, Takao Yasui, Takeshi Yanagida, Noritada Kaji, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    Analytical Sciences, 34, 12, 1347, 1349, 2018年, [査読有り]
    英語, 研究論文(学術雑誌), © 2018 The Japan Society for Analytical Chemistry. We have demonstrated a PM 2.5 analysis method that adds information on the number concentration and size by using microfluidic-based ionic current sensing with a bridge circuit. The bridge circuit allows for suppression of the background current and the detection of small PM 2.5 particles, even if a relatively large micropore is used. This is the first demonstration of the detection of PM 2.5 particles via ionic current sensing; our method enables analyses of both the number concentration and size.
  • Biomolecular recognition on nanowire surfaces modified by the self-assembled monolayer
    Taisuke Shimada, Takao Yasui, Asami Yokoyama, Tatsuro Goda, Mitsuo Hara, Takeshi Yanagida, Noritada Kaji, Masaki Kanai, Kazuki Nagashima, Yuji Miyahara, Tomoji Kawai, Yoshinobu Baba
    Lab on a Chip, 18, 21, 3225, 3229, 2018年, [査読有り]
    英語, 研究論文(学術雑誌), © 2018 The Royal Society of Chemistry. Molecular recognition is one of the key factors in designing biosensors due to which nanowires functionalized with molecular recognition have attracted a lot of attention as promising candidates for nanostructures embedded in biosensors. However, the difficulty in real-world applications with analytical specificity is that molecular recognition on nanowires mainly depends on antibody modification with multistep modification procedures. Furthermore, the antibody modification suffers from nonspecific adsorption of undesired proteins in body fluid on the nanowires, which causes false responses and lowers sensitivity. Herein, we propose biomolecular recognition using surface-modified nanowires via thiolated 2-methacryloxyethyl phosphorylcholine (MPC-SH). MPC-SH enables self-assembled monolayer (SAM) modification, which contributes to the reduction of nonspecific adsorption of biomolecules onto the nanowires, and the specific capture of a target protein is attained in the presence of calcium ions. Our concept demonstrates the recognition of the biomarker protein on nanowire surfaces modified by MPC-SH SAM with a single step modification procedure.
  • Effect of channel geometry on ionic current signal of a bridge circuit based microfluidic channel
    Hirotoshi Yasaki, Takao Yasui, Takeshi Yanagida, Noritada Kaji, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    Chemistry Letters, 47, 3, 350, 353, 2018年, [査読有り]
    英語, 研究論文(学術雑誌), © 2018 The Chemical Society of Japan. Bridge circuit based ionic current sensing in a microfluidic channel has attracted attention as a highly sensitive analytical method for bio-related molecules and particles. However, channel geometry which greatly influences the detected ionic current has not been investigated. Here, we investigate experimentally and theoretically the effect of differences in the microfluidic channel geometry on shapes and amplitude of signals in ionic current sensing. Our results clarify the geometrical effect of the channel in the bridge circuit based ionic current sensing method.
  • Discriminating single-bacterial shape using low-aspect-ratio pores
    Makusu Tsutsui, Takeshi Yoshida, Kazumichi Yokota, Hirotoshi Yasaki, Takao Yasui, Akihide Arima, Wataru Tonomura, Kazuki Nagashima, Takeshi Yanagida, Noritada Kaji, Masateru Taniguchi, Takashi Washio, Yoshinobu Baba, Tomoji Kawai
    SCIENTIFIC REPORTS, 7, 17371, NATURE PUBLISHING GROUP, 2017年12月, [査読有り]
    英語, 研究論文(学術雑誌), Conventional concepts of resistive pulse analysis is to discriminate particles in liquid by the difference in their size through comparing the amount of ionic current blockage. In sharp contrast, we herein report a proof-of-concept demonstration of the shape sensing capability of solid-state pore sensors by leveraging the synergy between nanopore technology and machine learning. We found ionic current spikes of similar patterns for two bacteria reflecting the closely resembled morphology and size in an ultra-low thickness-to-diameter aspect-ratio pore. We examined the feasibility of a machine learning strategy to pattern-analyse the sub-nanoampere corrugations in each ionic current waveform and identify characteristic electrical signatures signifying nanoscopic differences in the microbial shape, thereby demonstrating discrimination of single-bacterial cells with accuracy up to 90%. This data-analytics-driven microporescopy capability opens new applications of resistive pulse analyses for screening viruses and bacteria by their unique morphologies at a single-particle level.
  • Unveiling massive numbers of cancer-related urinary-microRNA candidates via nanowires
    Takao Yasui, Takeshi Yanagida, Satoru Ito, Yuki Konakade, Daiki Takeshita, Tsuyoshi Naganawa, Kazuki Nagashima, Taisuke Shimada, Noritada Kaji, Yuta Nakamura, Ivan Adiyasa Thiodorus, Yong He, Sakon Rahong, Masaki Kanai, Hiroshi Yukawa, Takahiro Ochiya, Tomoji Kawai, Yoshinobu Baba
    SCIENCE ADVANCES, 3, 12, e1701133, AMER ASSOC ADVANCEMENT SCIENCE, 2017年12月, [査読有り]
    英語, 研究論文(学術雑誌), Analyzing microRNAs (miRNAs) within urine extracellular vesicles (EVs) is important for realizing miRNA-based, simple, and noninvasive early disease diagnoses and timely medical checkups. However, the inherent difficulty in collecting dilute concentrations of EVs (<0.01 volume %) from urine has hindered the development of these diagnoses and medical checkups. We propose a device composed of nanowires anchored into a microfluidic substrate. This device enables EV collections at high efficiency and in situ extractions of various miRNAs of different sequences (around 1000 types) that significantly exceed the number of species being extracted by the conventional ultracentrifugation method. The mechanical stability of nanowires anchored into substrates during buffer flow and the electrostatic collection of EVs onto the nanowires are the two key mechanisms that ensure the success of the proposed device. In addition, we use our methodology to identify urinary miRNAs that could potentially serve as biomarkers for cancer not only for urologic malignancies (bladder and prostate) but also for nonurologic ones (lung, pancreas, and liver). The present device concept will provide a foundation for work toward the long-term goal of urine-based early diagnoses and medical checkups for cancer.
  • Long-Term Stability of Oxide Nanowire Sensors via Heavily Doped Oxide Contact               
    Hao Zeng, Tsunaki Takahashi, Masaki Kanai, Guozhu Zhang, Yong He, Kazuki Nagashima, Takeshi Yanagida
    ACS Sensors, 2, 12, 1854, 1859, 2017年10月, [査読有り]
    英語, 研究論文(学術雑誌)
  • Substantial Expansion of Detectable Size Range in Ionic Current Sensing through Pores by Using a Microfluidic Bridge Circuit               
    Hirotoshi Yasaki, Takao Yasui, Takeshi Yanagida, Noritada Kaji, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    Journal of the American Chemical Society, 139, 40, 14137, 14142, 2017年09月, [査読有り]
    英語, 研究論文(学術雑誌)
  • 結晶成長界面がSnO2ナノワイヤトランジスタ特性に与える影響の解明
    Zhu Zetao, 高橋 綱己, 安西 宇宙, 金井 真樹, Zhang Guozhu, He Yong, 長島 一樹, 柳田 剛
    応用物理学会学術講演会講演予稿集, 2017.2, 1908, 1908, 公益社団法人 応用物理学会, 2017年08月25日
    日本語
  • True Vapor–Liquid–Solid Process Suppresses Unintentional Carrier Doping of Single Crystalline Metal Oxide Nanowires
    Hiroshi Anzai, Masaru Suzuki, Kazuki Nagashima, Masaki Kanai, Zetao Zhu, Yong He, Mickaël Boudot, Guozhu Zhang, Tsunaki Takahashi, Katsuichi Kanemoto, Takehito Seki, Naoya Shibata, Takeshi Yanagida
    Nano Letters, 17, 8, 4698, 4705, American Chemical Society (ACS), 2017年07月, [査読有り]
    英語, 研究論文(学術雑誌)
  • Nanostructures Integrated with a Nanochannel for Slowing Down DNA Translocation Velocity for Nanopore Sequencing
    Xiaoyin Sun, Takao Yasui, Takeshi Yanagida, Noritada Kaji, Sakon Rahong, Masaki Kanai, Kazuki Nagashima, Tomoji Kawal, Yoshinobu Baba
    ANALYTICAL SCIENCES, 33, 6, 735, 738, JAPAN SOC ANALYTICAL CHEMISTRY, 2017年06月, [査読有り]
    英語, 研究論文(学術雑誌), Here, we developed a device integrated with a nanochannel and nanostructures to slow DNA translocation velocity. We found that translocation velocity of a single DNA molecule inside a nanochannel was decreased by pre-elongating it using some nanostructures, such as a shallow channel or nanopillars. This decrease of the translocation velocity was associated with the DNA mobility change, which is an intrinsic parameter of DNA molecules and unaffected by an electric field.
  • Effect of DNA Methylation on the Velocity of DNA Translocation through a Nanochannel
    Xiaoyin Sun, Takao Yasui, Takeshi Yanagida, Noritada Kaji, Sakon Rahong, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    ANALYTICAL SCIENCES, 33, 6, 727, 730, JAPAN SOC ANALYTICAL CHEMISTRY, 2017年06月, [査読有り]
    英語, 研究論文(学術雑誌), Here, we report the effect of DNA methylation on the velocity of DNA translocation through a nanochannel, as determined by measuring differences in translocation velocities between methylated and non-methylated DNA molecules. We found that the velocity of translocation of methylated DNA was faster than that of non-methylated DNA, which we attributed to variation in the coefficients of diffusion and friction with the nanochannel wall, due to the increased molecular weight and stiffness, respectively, of methylated DNA.
  • 固液界面アニール現象を利用した単結晶酸化物ナノワイヤのUnintentional Dopingの劇的抑制と超高純度化の実現
    安西 宇宙, 長島 一樹, 鈴木 将, Zhu Zetao, 金井 真樹, He Yong, Zhang Guozhu, 鐘本 勝一, 関 岳人, 柴田 直哉, 柳田 剛
    応用物理学会学術講演会講演予稿集, 2017.1, 1390, 1390, 公益社団法人 応用物理学会, 2017年03月01日
    日本語
  • A millisecond micro-RNA separation technique by a hybrid structure of nanopillars and nanoslits
    Qiong Wu, Noritada Kaji, Takao Yasui, Sakon Rahong, Takeshi Yanagida, Masaki Kanai, Kazuki Nagashima, Manabu Tokeshi, Tomoji Kawai, Yoshinobu Baba
    SCIENTIFIC REPORTS, 7, 43877, NATURE PUBLISHING GROUP, 2017年03月, [査読有り]
    英語, 研究論文(学術雑誌), A millisecond micro-RNA separation of a mixture of total RNA and genomic DNA, extracted from cultured HeLa cells, was successfully achieved using a hybrid structure of nanopillars and nanoslits contained inside a microchannel. The nanopillars, 250-nm in diameter and 100-nm in height, were fabricated with a 750-nm space inside the nanoslits, which were 100-nm in height and 25-mu m in width; the nanopillars were then applied as a new sieve matrix. This ultra-fast technique for the separation of miRNA can be an effective pretreatment for semiconductor nanopore DNA sequencing, which has an optimum reading speed of 1 base/ms to obtain effective signal-to-noise ratio and discriminate each base by ion or tunneling current during the passage of nucleic acids.
  • 空間選択性に立脚した単結晶金属酸化物ナノワイヤの創製とナノ物性・機能デバイス
    柳田 剛, 長島 一樹
    表面科学, 38, 7, 351, 356, 公益社団法人 日本表面科学会, 2017年
    日本語,

    Here we report our recent progress as to single crystalline metal oxide nanowires towards the nano-device applications. As the basis of such fundamental science, we focus on (1) formation technology of highly crystalline nanowires, (2) evaluation technology of single nanowire physical properties, and (3) control of spatial nanowire positions. Especially, I focus on our recent progress of our research group, which are related to single crystalline nanowires comprised of functional metal oxide materials and their memristive devices.

  • Rational Concept for Reducing Growth Temperature in Vapor–Liquid–Solid Process of Metal Oxide Nanowires               
    Zetao Zhu, Masaru Suzuki, Kazuki Nagashima, Hideto Yoshida, Masaki Kanai, Gang Meng, Hiroshi Anzai, Fuwei Zhuge, Yong He, Mickaël Boudot, Seiji Takeda, Takeshi Yanagida
    Nano Letters, 16, 12, 7495, 7502, 2016年11月, [査読有り]
    英語, 研究論文(学術雑誌)
  • Tailoring Nucleation at Two Interfaces Enables Single Crystalline NiO Nanowires via Vapor–Liquid–Solid Route
    Kazuki Nagashima, Hideto Yoshida, Annop Klamchuen, Masaki Kanai, Gang Meng, Fuwei Zhuge, Yong He, Hiroshi Anzai, Zetao Zhu, Masaru Suzuki, Mickaël Boudot, Seiji Takeda, Takeshi Yanagida
    ACS Applied Materials & Interfaces, 8, 41, 27892, 27899, AMER CHEMICAL SOC, 2016年10月, [査読有り]
    英語, 研究論文(学術雑誌), Here we show a rational strategy to fabricate single crystalline NiO nanowires via a vapor liquid solid (VLS) route, which essentially allows us to tailor the diameter and the spatial position. Our strategy is based on the suppression of the nucleation at vapor solid (VS) interface, which promotes nucleation only at the liquid solid (LS) interface. Manipulating both the supplied material fluxes (oxygen and metal) and the growth temperature enables enhancement of the nucleation only at the LS interface. Furthermore, this strategy allows us to reduce the growth temperature of single crystalline NiO nanowires down to 550 degrees C, which is the lowest growth temperature so far reported.
  • All-nanocellulose nonvolatile resistive memory
    Umberto Celano, Kazuki Nagashima, Hirotaka Koga, Masaya Nogi, Fuwei Zhuge, Gang Meng, Yong He, Jo De Boeck, Malgorzata Jurczak, Wilfried Vandervorst, Takeshi Yanagida
    NPG ASIA MATERIALS, 8, e310, NATURE PUBLISHING GROUP, 2016年09月, [査読有り]
    英語, 研究論文(学術雑誌), Single-use disposable nonvolatile memory devices hold promise for novel applications in internet of everything (IoE) technology by storing the health status of individual humans in daily life. However, conventional memory devices are not disposable because they are mostly composed of non-renewable, non-biodegradable and sometimes toxic materials, causing serious damage to ecological systems when they are released to the environment. Here, we demonstrate an environment-friendly, disposable nonvolatile memory device composed of 99.3 vol.% nanocellulose. Our memory device consists of a nanocellulose-based resistive-switching layer and a nanopaper substrate. The device exhibited nonvolatile resistive switching with the capability of multilevel storage and potential scalability down to the single nanofiber level (ca. 15 nm). The biodegradability of our memory device was confirmed by burying it in natural soil for 26 days.
  • Nanoscale Thermal Management of Single SnO2 Nanowire: pico-Joule Energy Consumed Molecule Sensor
    Gang Meng, Fuwei Zhuge, Kazuki Nagashima, Atsuo Nakao, Masaki Kanai, Yong He, Mickael Boudot, Tsunaki Takahashi, Ken Uchida, Takeshi Yanagida
    ACS SENSORS, 1, 8, 997, 1002, AMER CHEMICAL SOC, 2016年08月, [査読有り]
    英語, 研究論文(学術雑誌), Here we report the thermal management of oxide nanowire sensor in both spatial and time domains by utilizing unique thermal properties of nanowires, which are (1) the reduced thermal conductivity and (2) the short thermal relaxation time down to several microseconds. Our method utilizes a pulsed self-Joule-heating of suspended SnO2 nanowire device, which enables not only the gigantic reduction of energy consumption down to similar to 10(2) pJ/s, but also enhancement of the sensitivity for electrical sensing of NO2 (100 ppb). Furthermore, we demonstrate the applicability of the present method as sensors on flexible PEN substrate. Thus, this proposed thermal management concept of nanowires in both spatial and time domains offers a strategy for exploring novel functionalities of nanowire-based devices.
  • Microfluidic long-pore-channel to highlight bacteria contents
    H. Yasaki, T. Yasui, T. Yanagida, N. Kaji, M. Kanai, M. Fukuyama, K. Nagashima, T. Kawai, Y. Baba
    20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016, 100, 101, 2016年, [査読有り]
    英語, 研究論文(国際会議プロシーディングス), Ionic current sensing has realized sizing and counting of the number of biological samples, however, the sensing has never discriminated sample species in principle. Here, we showed the first case reported to date for discriminating sample species using microfluidic long-pore channel. The microfluidic long-pore channel could detect sample size, count sample number, and discriminate breaking of cell membrane of samples during sample passing through the long-pore channel. The present new approach should allow to develop an analytical tool not only for sizing and counting but for discriminating biological samples.
  • Simultaneous ionic current and optical detection of fine particulate matters (PM2.5) based on cross-junction microfluidic device
    S. Rahong, T. Yasui, H. Yasaki, T. Yanagida, M. Kanai, K. Nagashima, N. Kaji, T. Kawai, Y. Baba
    20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016, 1284, 1285, 2016年, [査読有り]
    英語, 研究論文(国際会議プロシーディングス), We present a simultaneous electrical and optical detection of particulate matter (PM) based on microfluidic chip for label-free and fast detection. The microfluidic system consists of the filters area for screening the large particles, which allows to pass through only particles smaller than 2.5μm, and the sensing area for detecting the particles using DC electrical measurements. As PM2.5 passed the cross-junction area, the disturbing electric fields would lead to fluctuating electric current in the detection circuit unit. Our measurement system has dynamic range from 200 nm to 2.5 μm. Furthermore, the amplitudes and the dwelling time of signals depended on the size of particulate matters that mean we would discriminate PM2.5 size in the range of millisecond (1-10 ms). Our system can detect a single particulate matter, which is applicable to count the number of PM2.5 for medical diagnostic, since the number of PM2.5 are found to be associated with several diseases.
  • Self-assembled monolayer and peptide coated nanowire devices for selective detection of C-reactive protein and E.coli without antibody
    A. Yokoyama, T. Yasui, T. Goda, T. Yanagida, M. Tanaka, M. Muto, M. Okochi, N. Kaji, M. Kanai, K. Nagashima, Y. Miyahara, T. Kawai, Y. Baba
    20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016, 1156, 1157, 2016年, [査読有り]
    英語, 研究論文(国際会議プロシーディングス), We developed surface-coated nanowire device with 2-methacryloyloxyethyl phosphorylcholine self-assembled monolayer for the detection of C-reactive protein (CRP) and phage display screened specific peptide for the detection of Escherichia coli (E. coli) without antibody. In this work, for achieving high-efficient target capturing we focused on combination of nanostructure and surface coating. We fabricated zinc oxide (ZnO) nanowire devices by hydrothermal synthesis and coated their surface with materials recognizing each biomarker without antibody. 3D structure of nanowire and surface coating enhanced target capture ability.
  • Identifying DNA methylation in a nanochannel
    Xiaoyin Sun, Takao Yasui, Takeshi Yanagida, Noritada Kaji, Sakon Rahong, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS, 17, 1, 644, 649, TAYLOR & FRANCIS LTD, 2016年, [査読有り]
    英語, 研究論文(学術雑誌), DNA methylation is a stable epigenetic modification, which is well known to be involved in gene expression regulation. In general, however, analyzing DNA methylation requires rather time consuming processes (24-96 h) via DNA replication and protein modification. Here we demonstrate a methodology to analyze DNA methylation at a single DNA molecule level without any protein modifications by measuring the contracted length and relaxation time of DNA within a nanochannel. Our methodology is based on the fact that methylation makes DNA molecules stiffer, resulting in a longer contracted length and a longer relaxation time (a slower contraction rate). The present methodology offers a promising way to identify DNA methylation without any protein modification at a single DNA molecule level within 2 h.
    [GRAPHICS]
    .
  • Rational Concept for Designing Vapor-Liquid-Solid Growth of Single Crystalline Metal Oxide Nanowires
    Annop Klamchuen, Masaru Suzuki, Kazuki Nagashima, Hideto Yoshida, Masaki Kanai, Fuwei Zhuge, Yong He, Gang Meng, Shoichi Kai, Seiji Takeda, Tomoji Kawai, Takeshi Yanagida
    NANO LETTERS, 15, 10, 6406, 6412, AMER CHEMICAL SOC, 2015年10月, [査読有り]
    英語, 研究論文(学術雑誌), Metal oxide nanowires hold great promise for various device applications due to their unique and robust physical properties in air and/or water and also due to their abundance on Earth. Vapor liquid solid (VLS) growth of metal oxide nanowires offers the high controllability of their diameters and spatial positions. In addition, VLS growth has applicability to axial and/or radial heterostructures, which are not attainable by other nanowire growth methods. However, material species available for the VLS growth of metal oxide nanowires are substantially limited even though the variety of material species, which has fascinating physical properties, is the most interesting feature of metal oxides. Here we demonstrate a rational design for the VLS growth of various metal oxide nanowires, based on the "material flux window". This material flux window describes the concept of VLS nanowire growth within a limited material flux range, where nucleation preferentially occurs only at a liquid solid interface. Although the material flux was previously thought to affect primarily the growth rate, we experimentally and theoretically demonstrate that the material flux is the important experimental variable for the VLS growth of metal oxide nanowires. On the basis of the material flux window concept, we discover novel metal oxide nanowires, composed of MnO, CaO, Sm2O3, NiO, and Eu2O3, which were previously impossible to form via the VLS route. The newly grown NiO nanowires exhibited stable memristive properties superior to conventional polycrystalline devices due to the single crystallinity. Thus, this VLS design route offers a useful guideline for the discovery of single crystalline nanowires that are composed of functional metal oxide materials.
  • Three-dimensional Nanowire Structures for Ultra-Fast Separation of DNA, Protein and RNA Molecules
    Sakon Rahong, Takao Yasui, Takeshi Yanagida, Kazuki Nagashima, Masaki Kanai, Gang Meng, Yong He, Fuwei Zhuge, Noritada Kaji, Tomoji Kawai, Yoshinobu Baba
    SCIENTIFIC REPORTS, 5, 10584, NATURE PUBLISHING GROUP, 2015年06月, [査読有り]
    英語, 研究論文(学術雑誌), Separation and analysis of biomolecules represent crucial processes for biological and biomedical engineering development; however, separation resolution and speed for biomolecules analysis still require improvements. To achieve separation and analysis of biomolecules in a short time, the use of highly-ordered nanostructures fabricated by top-down or bottom-up approaches have been proposed. Here, we reported on the use of three-dimensional (3D) nanowire structures embedded in microchannels fabricated by a bottom-up approach for ultrafast separation of small biomolecules, such as DNA, protein, and RNA molecules. The 3D nanowire structures could analyze a mixture of DNA molecules (50-1000 bp) within 50 s, a mixture of protein molecules (20-340 kDa) within 5 s, and a mixture of RNA molecules (100-1000 bases) within 25 s. And, we could observe the electrophoretic mobility difference of biomolecules as a function of molecular size in the 3D nanowire structures. Since the present methodology allows users to control the pore size of sieving materials by varying the number of cycles for nanowire growth, the 3D nanowire structures have a good potential for use as alternatives for other sieving materials.
  • Self-assembled Nanowire Arrays as Three-dimensional Nanopores for Filtration of DNA Molecules
    Sakon Rahong, Takao Yasui, Takeshi Yanagida, Kazuki Nagashima, Masaki Kanai, Gang Meng, Yong He, Fuwei Zhuge, Noritada Kaji, Tomoji Kawai, Yoshinobu Baba
    ANALYTICAL SCIENCES, 31, 3, 153, 157, JAPAN SOC ANALYTICAL CHEMISTRY, 2015年03月, [査読有り]
    英語, 研究論文(学術雑誌), Molecular filtration and purification play important roles for biomolecule analysis. However, it is still necessary to improve efficiency and reduce the filtration time. Here, we show self-assembled nanowire arrays as three-dimensional (3D) nanopores embedded in a microfluidic channel for ultrafast DNA filtration. The 3D nanopore structure was formed by a vapor-liquid-solid (VLS) nanowire growth technique, which allowed us to control pore size of the filtration material by varying the number of growth cycles. lambda DNA molecules (48.5 kbp) were filtrated from a mixture of T4 DNA (166 kbp) at the entrance of the 3D nanopore structure within 1 s under an applied electric field. Moreover, we observed single DNA molecule migration of T4 and lambda DNA molecules to clarify the filtration mechanism. The 3D nanopore structure has simplicity of fabrication, flexibility of pore size control and reusability for biomolecule filtration. Consequently it is an excellent material for biomolecular filtration.
  • A Oxide Nanowire for Probing Nanoscale Memristive Switching
    Kazuki Nagashima, Takeshi Yanagida, Masaki Kanai, Tomoji Kawai
    2015 IEEE 15TH INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY (IEEE-NANO), 120, 123, IEEE, 2015年, [査読有り]
    英語, 研究論文(国際会議プロシーディングス), Memristive switching, which is nonvolatile resistive switching in metal/oxide/metal sandwich structures, have attracted considerable attention not only for the next-generation nonvolatile memory but also for the artificial neural network computing. Despite the excellent memory performance, the physical origin of memristive switching occurring in the simple two terminal device structure had been missing, which was a central issue of this research field. It was widely accepted that the memristive switching is governed by formation and rupture of nanoscale conducting path in insulative matrix, however, extracting and evaluating such nanoscale conduction paths was difficult due to the lack of evaluation method. In this study, we demonstrate a unique approach to reveal the nature of memristive switching by using an oxide nanowire. The oxide nanowire successfully extracted the nanoscale conduction path and revealed the redox based conduction mechanism with the direct experimental evidence, which had been unfeasible in conventional thin film device form. The obtained results captured the many intrinsic features of memristive switching.
  • Conformation and dynamic behavior of single DNA molecules in nanofluidic channels for detection of DNA methylation
    X. Sun, T. Yasui, S. Rahong, T. Yanagida, N. Kaji, M. Kanai, K. Nagashima, T. Kawai, Y. Baba
    MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences, 1115, 1117, 2015年, [査読有り]
    英語, 研究論文(国際会議プロシーディングス), © 15CBMS-0001. In this paper, the single DNA molecules were linearized and stretched by using the nanochannel with a dimension of about 300 × 300 nm2 under applying electric fields. After that, the single DNA molecules methylation level was detected by estimating the contraction processes of both non-methylated and methylated single DNA molecules in nanochannel after switching off the electric fields. And furthermore, we also found that their translocation velocities were changed between non-methylated and methylated single DNA molecules in nanochannel.
  • Nanowire devices for extracellular vesicles analysis towards elucidation of intercellular communication
    Keiko Tabuchi, Takao Yasui, He Yong, Takeshi Yanagida, Noritada Kaji, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences, 1510, 1512, 2015年, [査読有り]
    英語, 研究論文(国際会議プロシーディングス), © 15CBMS-0001. We fabricate ZnO nanowires inside microchannels on Si substrates. Since the ZnO nanowires have positively charged surface [1] and most vesicles have negatively charged surface, it is able to capture the vesicles on the nanowire surface by electrostatic interaction. MicroRNA is extracted from the captured vesicles by introducing lysis buffer. It is expected that our fabricate devices would lead to fundamental understanding of cell-cell communication.
  • Modulation of Thermoelectric Power Factor via Radial Dopant Inhomogeneity in B-Doped Si Nanowires
    Fuwei Zhuge, Takeshi Yanagida, Naoki Fukata, Ken Uchida, Masaki Kanai, Kazuki Nagashima, Gang Meng, Yong He, Sakon Rahong, Xiaomin Li, Tomoji Kawai
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 136, 40, 14100, 14106, AMER CHEMICAL SOC, 2014年10月, [査読有り]
    英語, 研究論文(学術雑誌), We demonstrate a modulation of thermoelectric power factor via a radial dopant inhomogeneity in B-doped Si nanowires. These nanowires grown via vapor-liquid-solid (VLS) method were naturally composed of a heavily doped outer shell layer and a lightly doped inner core. The thermopower measurements for a single nanowire demonstrated that the power factor values were higher than those of homogeneously B-doped Si nanowires. The field effect measurements revealed the enhancement of hole mobility for these VLS grown B-doped Si nanowires due to the modulation doping effect. This mobility enhancement increases overall electrical conductivity of nanowires without decreasing the Seebeck coefficient value, resulting in the increase of thermoelectric power factor. In addition, we found that tailoring the surface dopant distribution by introducing surface delta-doping can further increase the power factor value. Thus, intentionally tailoring radial dopant inhomogeneity promises a way to modulate the thermoelectric power factor of semiconductor nanowires.
  • Nanoscale Size-Selective Deposition of Nanowires by Micrometer Scale Hydrophilic Patterns
    Yong He, Kazuki Nagashima, Masaki Kanai, Gang Meng, Fuwei Zhuge, Sakon Rahong, Xiaomin Li, Tomoji Kawai, Takeshi Yanagida
    SCIENTIFIC REPORTS, 4, 5943, NATURE PUBLISHING GROUP, 2014年08月, [査読有り]
    英語, 研究論文(学術雑誌), Controlling the post-growth assembly of nanowires is an important challenge in the development of functional bottom-up devices. Although various methods have been developed for the controlled assembly of nanowires, it is still a challenging issue to align selectively heterogeneous nanowires at desired spatial positions on the substrate. Here we report a size selective deposition and sequential alignment of nanowires by utilizing micrometer scale hydrophilic/hydrophobic patterned substrate. Nanowires dispersed within oil were preferentially deposited only at a water/oil interface onto the hydrophilic patterns. The diameter size of deposited nanowires was strongly limited by the width of hydrophilic patterns, exhibiting the nanoscale size selectivity of nanowires deposited onto micrometer scale hydrophilic patterns. Such size selectivity was due to the nanoscale height variation of a water layer formed onto the micrometer scale hydrophilic patterns. We successfully demonstrated the sequential alignment of different sized nanowires on the same substrate by applying this size selective phenomenon.
  • Cellulose Nanofiber Paper as an Ultra Flexible Nonvolatile Memory
    Kazuki Nagashima, Hirotaka Koga, Umberto Celano, Fuwei Zhuge, Masaki Kanai, Sakon Rahong, Gang Meng, Yong He, Jo De Boeck, Malgorzata Jurczak, Wilfried Vandervorst, Takuya Kitaoka, Masaya Nogi, Takeshi Yanagida
    SCIENTIFIC REPORTS, 4, 5532, NATURE PUBLISHING GROUP, 2014年07月, [査読有り]
    英語, 研究論文(学術雑誌), On the development of flexible electronics, a highly flexible nonvolatile memory, which is an important circuit component for the portability, is necessary. However, the flexibility of existing nonvolatile memory has been limited, e.g. the smallest radius into which can be bent has been millimeters range, due to the difficulty in maintaining memory properties while bending. Here we propose the ultra flexible resistive nonvolatile memory using Ag-decorated cellulose nanofiber paper (CNP). The Ag-decorated CNP devices showed the stable nonvolatile memory effects with 6 orders of ON/OFF resistance ratio and the small standard deviation of switching voltage distribution. The memory performance of CNP devices can be maintained without any degradation when being bent down to the radius of 350 mu m, which is the smallest value compared to those of existing any flexible nonvolatile memories. Thus the present device using abundant and mechanically flexible CNP offers a highly flexible nonvolatile memory for portable flexible electronics.
  • Ultrafast and Wide Range Analysis of DNA Molecules Using Rigid Network Structure of Solid Nanowires
    Sakon Rahong, Takao Yasui, Takeshi Yanagida, Kazuki Nagashima, Masaki Kanai, Annop Klamchuen, Gang Meng, Yong He, Fuwei Zhuge, Noritada Kaji, Tomoji Kawai, Yoshinobu Baba
    SCIENTIFIC REPORTS, 4, 5252, NATURE PUBLISHING GROUP, 2014年06月, [査読有り]
    英語, 研究論文(学術雑誌), Analyzing sizes of DNA via electrophoresis using a gel has played an important role in the recent, rapid progress of biology and biotechnology. Although analyzing DNA over a wide range of sizes in a short time is desired, no existing electrophoresis methods have been able to fully satisfy these two requirements. Here we propose a novel method using a rigid 3D network structure composed of solid nanowires within a microchannel. This rigid network structure enables analysis of DNA under applied DC electric fields for a large DNA size range (100 bp-166 kbp) within 13 s, which are much wider and faster conditions than those of any existing methods. The network density is readily varied for the targeted DNA size range by tailoring the number of cycles of the nanowire growth only at the desired spatial position within the microchannel. The rigid dense 3D network structure with spatial density control plays an important role in determining the capability for analyzing DNA. Since the present method allows the spatial location and density of the nanostructure within the microchannels to be defined, this unique controllability offers a new strategy to develop an analytical method not only for DNA but also for other biological molecules.
  • A flux induced crystal phase transition in the vapor–liquid–solid growth of indium-tin oxide nanowires
    Gang Meng, Takeshi Yanagida, Hideto Yoshida, Kazuki Nagashima, Masaki Kanai, Fuwei Zhuge, Yong He, Annop Klamchuen, Sakon Rahong, Seiji Takeda, Tomoji Kawai
    Nanoscale, 6, 12, 7033, 7038, ROYAL SOC CHEMISTRY, 2014年, [査読有り]
    英語, 研究論文(学術雑誌), Single crystalline metal oxide nanowires formed via a vapor-liquid-solid (VLS) route provide a platform not only for studying fundamental nanoscale properties but also for exploring novel device applications. Although the crystal phase variation of metal oxides, which exhibits a variety of physical properties, is an interesting feature compared with conventional semiconductors, it has been difficult to control the crystal phase of metal oxides during the VLS nanowire growth. Here we show that a material flux critically determines the crystal phase of indium-tin oxide nanowires grown via the VLS route, although thermodynamical parameters, such as temperature and pressure, were previously believed to determine the crystal phase. The crystal phases of indium-tin oxide nanowires varied from the rutile structures (SnO2), the metastable fluorite structures (InxSnyO3.5) and the bixbyite structures (Sn-doped In2O3) when only the material flux was varied within an order of magnitude. This trend can be interpreted in terms of the material flux dependence of crystal phases (rutile SnO2 and bixbyite In2O3) on the critical nucleation at the liquid-solid (LS) interface. Thus, precisely controlling the material flux, which has been underestimated for VLS nanowire growths, allows us to design the crystal phase and properties in the VLS nanowire growth of multicomponent metal oxides.
  • Advanced photoassisted atomic switches produced using ITO nanowire electrodes and molten photoconductive organic semiconductors
    Annop Klamchuen, Hirofumi Tanaka, Daisuke Tanaka, Hirotaka Toyama, Gang Meng, Sakon Rahong, Kazuki Nagashima, Masaki Kanai, Takeshi Yanagida, Tomoji Kawai, Takuji Ogawa
    Advanced Materials, 25, 41, 5893, 5897, 2013年11月06日, [査読有り]
    英語, 研究論文(学術雑誌), Photoassisted atomic switches (PASs) are those produced using photoconductive organic materials. However, the use of solid photoconductive materials and the formation of a large Ag conductive bridge lead to the formation of large voids during the shrinking of Ag conductive bridges
    this may degrade the performance of PASs. A low-melting-point organic semiconductor is used as a molten photoconductive material, and self-assembled ITO nanowires are used as transparent electrodes. Stable atomic switching is observed only under light irradiation. © 2013 WILEY-VCH Verlag GmbH &
    Co. KGaA, Weinheim.
  • Carrier type dependence on spatial asymmetry of unipolar resistive switching of metal oxides
    Kazuki Nagashima, Takeshi Yanagida, Masaki Kanai, Umberto Celano, Sakon Rahong, Gang Meng, Fuwei Zhuge, Yong He, Bae Ho Park, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 103, 17, 173506, AMER INST PHYSICS, 2013年10月, [査読有り]
    英語, 研究論文(学術雑誌), We report a carrier type dependence on the spatial asymmetry of unipolar resistive switching for various metal oxides, including NiOx, CoOx, TiO2-x, YSZ, and SnO2-x. n-type oxides show a unipolar resistive switching at the anode side whereas p-type oxides switch at the cathode side. During the forming process, the electrical conduction path of p-type oxides extends from the anode to cathode while that of n-type oxides forms from the cathode to anode. The carrier type of switching oxide layer critically determines the spatial inhomogeneity of unipolar resistive switching during the forming process possibly triggered via the oxygen ion drift. (C) 2013 AIP Publishing LLC.
  • Impact of Preferential Indium Nucleation on Electrical Conductivity of Vapor-Liquid-Solid Grown Indium-Tin Oxide Nanowires
    Gang Meng, Takeshi Yanagida, Kazuki Nagashima, Hideto Yoshida, Masaki Kanai, Annop Klamchuen, Fuwei Zhuge, Yong He, Sakon Rahong, Xiaodong Fang, Seiji Takeda, Tomoji Kawai
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 135, 18, 7033, 7038, AMER CHEMICAL SOC, 2013年05月, [査読有り]
    英語, 研究論文(学術雑誌), Highly conductive and transparent indium-tin oxide (ITO) single-crystalline nanowires, formed by the vapor- liquid-solid (VLS) method, hold great promise for various nanoscale device applications. However, increasing an electrical conductivity of VLS grown ITO nanowires is still a challenging issue due to the intrinsic difficulty in controlling complex material transports of the VLS process. Here, we demonstrate a crucial role of preferential indium nucleation on the electrical conductivity of VLS grown ITO nanowires using gold catalysts. In spite of the fact that the vapor pressure of tin is lower than that of indium, we found that the indium concentration within the nanowires was always higher than the nominal composition. The VLS growth of ITO through gold catalysts significantly differs from ITO film formations due to the emergence of preferential indium nucleation only at a liquid-solid interface. Furthermore, we demonstrate that the averaged resistivity of ITO nanowires can be decreased down to 2.1 x 10(-4) Omega cm, which is the lowest compared with values previously reported, via intentionally increasing the tin concentration within the nanowires.
  • Scaling Effect on Unipolar and Bipolar Resistive Switching of Metal Oxides
    Takeshi Yanagida, Kazuki Nagashima, Keisuke Oka, Masaki Kanai, Annop Klamchuen, Bae Ho Park, Tomoji Kawai
    SCIENTIFIC REPORTS, 3, 1657, NATURE PUBLISHING GROUP, 2013年04月, [査読有り]
    英語, 研究論文(学術雑誌), Electrically driven resistance change in metal oxides opens up an interdisciplinary research field for next-generation non-volatile memory. Resistive switching exhibits an electrical polarity dependent "bipolar-switching'' and a polarity independent "unipolar-switching'', however tailoring the electrical polarity has been a challenging issue. Here we demonstrate a scaling effect on the emergence of the electrical polarity by examining the resistive switching behaviors of Pt/oxide/Pt junctions over 8 orders of magnitudes in the areas. We show that the emergence of two electrical polarities can be categorised as a diagram of an electric field and a cell area. This trend is qualitatively common for various oxides including NiOx, CoOx, and TiO2-x. We reveal the intrinsic difference between unipolar switching and bipolar switching on the area dependence, which causes a diversity of an electrical polarity for various resistive switching devices with different geometries. This will provide a foundation for tailoring resistive switching behaviors of metal oxides.
  • DNA manipulation and separation in sublithographic-scale nanowire array
    Takao Yasui, Sakon Rahong, Koki Motoyama, Takeshi Yanagida, Qiong Wu, Noritada Kaji, Masaki Kanai, Kentaro Doi, Kazuki Nagashima, Manabu Tokeshi, Masateru Taniguchi, Satoyuki Kawano, Tomoji Kawai, Yoshinobu Baba
    ACS Nano, 7, 4, 3029, 3035, 2013年04月, [査読有り]
    英語, 研究論文(学術雑誌), Electrokinetic manipulations of biomolecules using artificial nanostructures within microchannels have proven capability for controlling the dynamics of biomolecules. Because there is an inherent spatial size limitation to lithographic technology, especially for nanostructures with a small diameter and high aspect ratio, manipulating a single small biomolecule such as in DNA elongation before nanopore sequencing is still troublesome. Here we show the feasibility for self-assembly of a nanowire array embedded in a microchannel on a fused silica substrate as a means to manipulate the dynamics of a single long T4-DNA molecule and also separate DNA molecules. High-resolution optical microscopy measurements are used to clarify the presence of fully elongated T4-DNA molecules in the nanowire array. The spatial controllability of sublithographic-scale nanowires within microchannels offers a flexible platform not only for manipulating and separating long DNA molecules but also for integrating with other nanostructures to detect biomolecules in methods such as nanopore sequencing. © 2013 American Chemical Society.
  • Pressure-induced evaporation dynamics of gold nanoparticles on oxide substrate
    Gang Meng, Takeshi Yanagida, Masaki Kanai, Masaru Suzuki, Kazuki Nagashima, Bo Xu, Fuwei Zhuge, Annop Klamchuen, Yong He, Sakon Rahong, Shoichi Kai, Tomoji Kawai
    PHYSICAL REVIEW E, 87, 1, 012405, AMER PHYSICAL SOC, 2013年01月, [査読有り]
    英語, 研究論文(学術雑誌), Here we report thermal evaporation dynamics of Au nanoparticles on single crystal oxide substrates, including MgO, SrTiO3, and Al2O3. The size reduction rate of Au nanoparticles via thermal treatments is strongly dependent on not only temperature but also pressure. Lowering the pressure of inert Ar gas from 10(5) to 10 Pa increases the size reduction rate over 30 times in the temperature range 800 degrees C-950 degrees C. The temperature dependence is solely due to the variation of saturated vapor pressure of Au, whereas the pressure dependence of the surrounding inert gas can be interpreted in terms of a pressure dependence on a gas-phase diffusion of evaporated Au atoms into the surroundings. We present a simplified model to explain an evaporation dynamics, which well describes the pressure dependence on a size reduction rate of Au nanoparticles. By utilizing this useful pressure- induced evaporation dynamics, we succeeded in manipulating a size reduction of Au nanoparticle arrays down to - 10 nm diameter range from - 300 nm initial size by programming sequentially a surrounding pressure. DOI: 10.1103/PhysRevE.87.012405
  • Crystal-Plane Dependence of Critical Concentration for Nucleation on Hydrothermal ZnO Nanowires
    Yong He, Takeshi Yanagida, Kazuki Nagashima, Fuwei Zhuge, Gang Meng, Bo Xu, Annop Klamchuen, Sakon Rahong, Masaki Kanai, Xiaomin Li, Masaru Suzuki, Shoichi Kai, Tomoji Kawai
    JOURNAL OF PHYSICAL CHEMISTRY C, 117, 2, 1197, 1203, AMER CHEMICAL SOC, 2013年01月, [査読有り]
    英語, 研究論文(学術雑誌), Hydrothermal ZnO nanowires have shown great potential for various nanoscale device applications due to their fascinating properties and low-temperature processing. A preferential crystal growth of ZnO (0001) polar plane is essential and fundamental to realize the anisotropic nanowire growth. Here we demonstrate that a critical concentration for a nucleation strongly depends on a crystal plane, which plays an important role on an anisotropic growth of hydrothermal ZnO nanowires. We measure a growth rate of each crystal plane when varying a concentration of Zn ionic species by using a regular array structure. Selective anisotropic growth on (0001) plane emerges within a certain concentration range. Above the concentration range, a crystal growth on (10 (1) over bar0) plane tends to simultaneously occur. This strong concentration dependence on the crystal plane is understood in terms of a critical concentration difference between (0001) plane and (10 (1) over bar0) plane, which is related to the surface energy difference between the crystal planes.
  • DNA methylation mapping in nanoslit devices at a single molecule level
    Mayu Mizutani, Takao Yasui, Nortada Kaji, Sakon Rahong, Takeshi Yanagida, Masaki Kanai, Kazuki Nagashima, Tomoji Kawai, Yoshinobu Baba
    17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013, 1, 29, 31, 2013年, [査読有り]
    研究論文(国際会議プロシーディングス), We demonstrated methylation mapping of DNA molecules specifically in nanoslit devices by using the quantum dots (QDs) combined with methyl-CpG-binding domain protein (MBDp) at a single molecule level. We fabricated nanoslit devices for fully elongation of DNA molecules. We measured the methylation sites using QDs-MBDp complexes in the nanoslit devices at a single molecule level. We found that these methylation sites showed a good agreement with the enzymatic sites of the methyltransferase. Copyright © (2013) by the Chemical and Biological Microsystems Society All rights reserved.
  • Fundamental Strategy for Creating VLS Grown TiO2 Single Crystalline Nanowires
    Fuwei Zhuge, Takeshi Yanagida, Kazuki Nagashima, Hideto Yoshida, Masaki Kanai, Bo Xu, Annop Klamchuen, Gang Meng, Yong He, Sakon Rahong, Xiaomin Li, Masaru Suzuki, Shoichi Kai, Seiji Takeda, Tomoji Kawai
    JOURNAL OF PHYSICAL CHEMISTRY C, 116, 45, 24367, 24372, AMER CHEMICAL SOC, 2012年11月, [査読有り]
    英語, 研究論文(学術雑誌), A single crystalline TiO2 nanowire grown by a size and position controllable vapor liquid solid (VLS) method is a promising candidate to control and design the physical and chemical properties for various TiO2-based applications. However, creating TiO2 nanowires by VLS has been a challenging issue due to a difficulty on controlling and understanding the complex material transport events across three phases. Here we propose a fundamental strategy to create a TiO2 single crystalline nanowire by the VLS mechanism. We show that a VLS growth of TiO2 nanowires can emerge intrinsically only within a quite narrow range of material flux, which is a sharp contrast to typical VLS oxides including MgO, SnO2, In2O3, and ZnO, whose nanowires are easily grown by VLS with much wider ranges of material flux. We reveal that a condensation of Ti atoms at a vapor solid interface, which is detrimental for VLS, is responsible to limit a window of material flux for TiO2 nanowires. In addition, we found that our rutile-TiO2 nanowires preferentially grow along < 001 > direction, which interestingly differs from a typical < 110 > oriented growth of TiO2 nanowires formed by the vapor phase method. The present approach based on a control of material flux provides a foundation to tailor VLS grown TiO2 nanowires based on a scientific strategy rather than a rule of thumb.
  • Switching Properties of Titanium Dioxide Nanowire Memristor
    Kazuki Nagashima, Takeshi Yanagida, Masaki Kanai, Keisuke Oka, Annop Klamchuen, Sakon Rahong, Gang Meng, Mati Horprathum, Bo Xu, Fuwei Zhuge, Yong He, Tomoji Kawai
    JAPANESE JOURNAL OF APPLIED PHYSICS, 51, 11, 11PE09, JAPAN SOC APPLIED PHYSICS, 2012年11月, [査読有り]
    英語, 研究論文(学術雑誌), We present the memristive switching properties in a single nanowire device made of titanium dioxide. We constructed the single oxide nanowire device made of titanium dioxide on a Si substrate. First, we confirmed the existence of memristive switching in a 10 nm scale nanowire device. We successfully extracted the carrier-types for memristive switching by utilizing atmosphere control measurements. Although cobalt oxide and nickel oxide showed the p-type behavior reported previously, the present titanium dioxide nanowire memristor exhibited n-type behavior. Our results highlight the fact that carrier-type of memristive switching seems to be consistent with that of a bulk material, but this is in fact somehow contradictive to a model based on precipitation of metals within an oxide matrix. Since, in conventional capacitor-type memristors, it has been impossible to measure the carrier-type in memristive switching because memristive events are buried within a solid, the open-top planar-type "nanowire memristor" is clearly a powerful device for extracting the intrinsic features of memristive switching phenomena. (C) 2012 The Japan Society of Applied Physics
  • Prominent Thermodynamical Interaction with Surroundings on Nanoscale Memristive Switching of Metal Oxides
    Kazuki Nagashima, Takeshi Yanagida, Keisuke Oka, Masaki Kanai, Annop Klamchuen, Sakon Rahong, Gang Meng, Mati Horprathum, Bo Xu, Fuwei Zhuge, Yong He, Bae Ho Park, Tomoji Kawai
    NANO LETTERS, 12, 11, 5684, 5690, AMER CHEMICAL SOC, 2012年11月, [査読有り]
    英語, 研究論文(学術雑誌), This study demonstrates the effect of surroundings on a memristive switching at nanoscale. by utilizing an open top planar-type device. NiOx and CoOx planar-type devices. have exhibited a memristive behavior under atmospheric pressure, whereas TiO2-x planar-type devices did not show a memristive switching even under the same surroundings. A memristive behavior: of TiO2-x planar-type devices has emerged when reducing an ambient pressure and/or employing a SiO2 passivation layer. These results reveal that a thermodynamical interaction with surroundings critically . determines the occurrence of memristive Switching via varying a stability of nonstoichiometry. Since this effect tends to be more significant for smaller devices with larger specific surface area, tailoring the surrounding effect by an appropriate passivation will be essential for high density devices.
  • Dual Defects of Cation and Anion in Memristive Nonvolatile Memory of Metal Oxides
    Keisuke Oka, Takeshi Yanagida, Kazuki Nagashima, Masaki Kanai, Bo Xu, Bae Ho Park, Hiroshi Katayama-Yoshida, Tomoji Kawai
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 134, 5, 2535, 2538, AMER CHEMICAL SOC, 2012年02月, [査読有り]
    英語, 研究論文(学術雑誌), The electrically driven resistance change of metal oxides, called bipolar memristive switching, is a fascinating phenomenon in the development of next-generation nonvolatile memory alternatives to flash technology. However, our understanding of the nature of bipolar memristive switching is unfortunately far from comprehensive, especially the relationship between the electrical transport and the local nonstoichiometry. Here we demonstrate that the coexistence of anion and cation defects is critical to the transport properties of NiO, one of the most promising memristive oxides, by utilizing first-principles calculations. We find that, in the presence of both nickel and oxygen defects, which must exist in any real experimental systems, carrier concentrations of holes generated by nickel defects can be modulated by the presence or absence of oxygen defects around the nickel defect. Such alternation of local nonstoichiometry can be understood in terms of an oxygen ion drift induced by an external electric field. This implication provides a foundation for understanding universally the nature of bipolar memristive switching in various p-type metal oxides.
  • Facile and scalable patterning of sublithographic scale uniform nanowires by ultra-thin AAO free-standing membrane
    Gang Meng, Takeshi Yanagida, Kazuki Nagashima, Takashi Yanagishita, Masaki Kanai, Keisuke Oka, Annop Klamchuen, Sakon Rahong, Mati Horprathum, Bo Xu, Fuwei Zhuge, Yong He, Hideki Masuda, Tomoji Kawai
    RSC ADVANCES, 2, 28, 10618, 10623, ROYAL SOC CHEMISTRY, 2012年, [査読有り]
    英語, 研究論文(学術雑誌), Creating sublithographic scale uniform nanowires for large area is an important issue for nanowire-based various device applications. Although anodic aluminium oxide (AAO) membrane is a promising technique, existing attached AAO membrane mask methods have not been able to fabricate such small nanowires for large areas due to difficulties on transferring a thin membrane. Here we demonstrate a facile and scalable methodology to fabricate sublithographic scale uniform-sized nanowires by introducing ultra-thin AAO free-standing membrane with a rigid Al frame and a hydrophilic contacting method. The present method allows us to fabricate sub 20 nm nanowires with the standard deviations of 1.1 nm via defining the size and spacing of metal catalysts for nanowire growth. We also show the scalability of the present attached AAO membrane mask method for a 4-inch scale wafer.
  • Study on transport pathway in oxide nanowire growth by using spacing-controlled regular array
    Annop Klamchuen, Takeshi Yanagida, Masaki Kanai, Kazuki Nagashima, Keisuke Oka, Sakon Rahong, Meng Gang, Mati Horprathum, Masaru Suzuki, Yoshiki Hidaka, Shoichi Kai, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 99, 19, 193105, AMER INST PHYSICS, 2011年11月, [査読有り]
    英語, 研究論文(学術雑誌), Metal oxide nanowires formed via vapor-liquid-solid (VLS) process are promising nanoscale building blocks. Although understanding material transport pathways across three phases is crucial to realize well-defined oxide nanowires, such knowledge is unfortunately far from comprehensive. Here we investigate the material transport pathway in VLS grown MgO nanowires by utilizing spacing-controlled regular array. Defining the regular spacing of catalysts allows us to extract the information of transport pathway for each catalyst. We found the significant contribution of vapor phase transport pathway rather than the surface diffusion transport. This result highlights the critical role of re-evaporation process on VLS oxide nanowires. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3660246]
  • Spatial Nonuniformity in Resistive-Switching Memory Effects of NiO
    Keisuke Oka, Takeshi Yanagida, Kazuki Nagashima, Masaki Kanai, Tomoji Kawai, Jin-Soo Kim, Bae Ho Park
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 133, 32, 12482, 12485, AMER CHEMICAL SOC, 2011年08月, [査読有り]
    英語, 研究論文(学術雑誌), Electrically driven resistance change phenomenon in metal/NiO/metal junctions, so-called resistive switching (RS), is a candidate for next-generation universal nonvolatile memories. However, the knowledge as to RS mechanisms is unfortunately far from comprehensive, especially the spatial switching location, which is crucial information to design reliable devices. In this communication, we demonstrate the identification of the spatial switching location of bipolar RS by introducing asymmetrically passivated planar NiO nanowire junctions. We have successfully identified that the bipolar RS in NiO occurs near the cathode rather than the anode. This trend can be interpreted in terms of an electrochemical redox model based on ion migration and p-type conduction.
  • Intrinsic Mechanisms of Memristive Switching
    Kazuki Nagashima, Takeshi Yanagida, Keisuke Oka, Masaki Kanai, Annop Klamchuen, Jin-Soo Kim, Bae Ho Park, Tomoji Kawai
    NANO LETTERS, 11, 5, 2114, 2118, AMER CHEMICAL SOC, 2011年05月, [査読有り]
    英語, 研究論文(学術雑誌), Resistive switching (RS) memory effect in metal-oxide-metal junctions is a fascinating phenomenon toward next-generation universal nonvolatile memories. However the lack of understanding the electrical nature of RS has held back the applications. Here we demonstrate the electrical nature of bipolar RS in cobalt oxides, such as the conduction mechanism and the switching location, by utilizing a planar single oxide nanowire device. Experiments utilizing field effect devices and multiprobe measurements have shown that the nanoscale RS in cobalt oxides originates from redox events near the cathode with p-type conduction paths, which is in contrast with the prevailing oxygen vacancy based model.
  • Dopant homogeneity and transport properties of impurity-doped oxide nanowires
    Annop Klamchuen, Takeshi Yanagida, Masaki Kanai, Kazuki Nagashima, Keisuke Oka, Shu Seki, Masaru Suzuki, Yoshiki Hidaka, Shoichi Kai, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 98, 5, 053107, AMER INST PHYSICS, 2011年01月, [査読有り]
    英語, 研究論文(学術雑誌), Controlling and understanding an impurity doping on semiconductor oxide nanowires grown by the vapor-liquid-solid (VLS) method remains an important challenge. Homogeneous dopant distribution within oxide nanowires has been assumed without the direct evaluations to interpret the transport properties. Here we report the direct measurements of dopant distributions for Ta-doped SnO(2) nanowires. We find that differences in dopant incorporations between VLS and vapor-solid growth processes give rise to a heavily doped shell surrounding an underdoped core. Thus, understanding the dopant incorporation pathways is essential to designing and controlling impurity doping on VLS grown oxide nanowires. (C) 2011 American Institute of Physics. [doi:10.1063/1.3549703]
  • Impurity induced periodic mesostructures in Sb-doped SnO2 nanowires
    Annop Klamchuen, Takeshi Yanagida, Masaki Kanai, Kazuki Nagashima, Keisuke Oka, Tomoji Kawai, Masaru Suzuki, Yoshiki Hidaka, Shoichi Kai
    JOURNAL OF CRYSTAL GROWTH, 312, 21, 3251, 3256, ELSEVIER SCIENCE BV, 2010年10月, [査読有り]
    英語, 研究論文(学術雑誌), Impurity doping on semiconductor nanowires formed via vapor-liquid-solid (VLS) mechanism has been investigated with the intention being to control the transport properties. Here we demonstrate that an addition of excess impurity dopants induces a mesostructure of long range periodic arched-shape in Sb-doped SnO2 nanowires. The microstructural and composition analysis demonstrated the importance of the presence of impurities at the growth interface during VLS growth rather than the dopant incorporation into nanowires, indicating kinetically induced mechanisms. (C) 2010 Published by Elsevier B.V.
  • Role of surrounding oxygen on oxide nanowire growth
    Annop Klamchuen, Takeshi Yanagida, Masaki Kanai, Kazuki Nagashima, Keisuke Oka, Tomoji Kawai, Masaru Suzuki, Yoshiki Hidaka, Shoichi Kai
    APPLIED PHYSICS LETTERS, 97, 7, 073114, AMER INST PHYSICS, 2010年08月, [査読有り]
    英語, 研究論文(学術雑誌), The ability to control oxide nanowires via vapor-liquid-solid (VLS) mechanism remains an important challenge to explore various applications of oxide nanowires. Here we demonstrate the crucial roles of surrounding oxygen on VLS grown SnO(2) nanowires. When the partial pressure of surrounding oxygen is relatively low, the oxygen mainly acts as an oxygen source, promoting VLS growth. While for relatively high oxygen partial pressures, vapor-solid (VS) growth emerges, suppressing nanowire growth. The findings as to the roles of surrounding oxygen on the inherent competition between VLS and VS growths are in principle rather universal for VLS grown nanowires of various oxides. (C) 2010 American Institute of Physics. [doi:10.1063/1.3474605]
  • Resistive-Switching Memory Effects of NiO Nanowire/Metal Junctions
    Keisuke Oka, Takeshi Yanagida, Kazuki Nagashima, Tomoji Kawai, Jin-Soo Kim, Bae Ho Park
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 132, 19, 6634, +, AMER CHEMICAL SOC, 2010年05月, [査読有り]
    英語, 研究論文(学術雑誌), We have demonstrated the construction of highly stable resistive switching (RS) junctions with a metal/NiO nanowire/metal structure and used them to elucidate the crucial role of redox events in the nanoscale bipolar RS. The presented approaches utilizing oxide nanowire/metal junctions offer an important system and platform for investigating nanoscale RS mechanisms of various oxide materials.
  • Resistive Switching Multistate Nonvolatile Memory Effects in a Single Cobalt Oxide Nanowire
    Kazuki Nagashima, Takeshi Yanagida, Keisuke Oka, Masateru Taniguchi, Tomoji Kawai, Jin-Soo Kim, Bae Ho Park
    NANO LETTERS, 10, 4, 1359, 1363, AMER CHEMICAL SOC, 2010年04月, [査読有り]
    英語, 研究論文(学術雑誌), A multistate nonvolatile memory operated at sublithographic scale has been strongly desired since other nonvolatile memories have confronted the fundamental size limits owing to their working principles. Resistive switching (RS) in metal-oxide-metal junctions, so-called ReRAM, is promising for next generation high-density nonvolatile memory. Self-assembled oxide nanowire-based RS offers an attractive solution not only to reduce the device size beyond the limitation of current lithographic length scales but also to extract the underlying nanoscale RS mechanisms. Here we demonstrate the multistate bipolar RS of a single Co(3)O(4) nanowire (10 nm scale) with the endurance up to 10(8). In addition, we succeeded to extract a voltage-induced nanoscale RS mechanism rather than current-induced RS. These Findings would open up opportunities to explore not only for the intrinsic nanoscale RS mechanisms with the ultimate size limit but also for next generation multistate three-dimensional ReRAM.
  • Interfacial effect on metal/oxide nanowire junctions
    Kazuki Nagashima, Takeshi Yanagida, Annop Klamchuen, Masaki Kanai, Keisuke Oka, Shu Seki, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 96, 7, 073110, AMER INST PHYSICS, 2010年02月, [査読有り]
    英語, 研究論文(学術雑誌), An interface in metal/oxide nanowire junctions plays a crucial role on the electronic device applications, especially two-terminal devices. Here we demonstrate the crucial role of interfacial effects on oxide (SnO(2-delta)) nanowire/Pt junctions. The resistivity estimated from the I-V data of the junctions was four orders of magnitudes higher than that measured by a noncontact microwave conductivity method. We found that such apparent discrepancy is due to the presence of insulating oxidized interfacial layer. Since most conductive oxides are typically n-type semiconductors via oxygen vacancies, above implications will be rather universal and crucial for reproducible emerging nanodevices using oxide nanowires. (C) 2010 American Institute of Physics. [doi:10.1063/1.3318257]
  • コバルト酸化物ナノワイヤ構造体における不揮発性抵抗変化メモリ効果
    長島 一樹, 柳田 剛, 岡 敬祐, 谷口 正輝, 川合 知二, Jinsoo Kim, Bae Ho Park
    化学工学会 研究発表講演要旨集, 2010, 231, 231, 公益社団法人 化学工学会, 2010年
    日本語
  • 気液固反応法による酸化物ナノワイヤ構造体の創製とメカニズム解明
    柳田 剛, Klamchuen Annop, 長島 一樹, 岡 敬祐, 川合 知二
    化学工学会 研究発表講演要旨集, 2010, 240, 240, 公益社団法人 化学工学会, 2010年
    日本語
  • Specific surface effect on transport properties of NiO/MgO heterostructured nanowires
    Keisuke Oka, Takeshi Yanagida, Kazuki Nagashima, Hidekazu Tanaka, Shu Seki, Yoshihito Honsho, Manabu Ishimaru, Akihiko Hirata, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 95, 13, 133110, AMER INST PHYSICS, 2009年09月, [査読有り]
    英語, 研究論文(学術雑誌), NiO heterostructured nanowires are promising building blocks due to the nonvolatile resistive switching in nanoscale. Here, we report on the noncontact transport measurements of single crystalline NiO/MgO heterostructured nanowires by utilizing a microwave conductivity method. We found the substantial discrepancy up to four orders of magnitude between the heterostructured nanowires and heterothin films on the resistivity when the bulk resistivity increased, whereas the reasonable agreement was found for relatively conductive range. The origin of such huge discrepancy was interpreted in terms of both the large specific surface area of nanowires and the surface transport events of insulative NiO. (C) 2009 American Institute of Physics. [doi:10.1063/1.3237176]
  • Crucial role of doping dynamics on transport properties of Sb-doped SnO2 nanowires
    Annop Klamchuen, Takeshi Yanagida, Kazuki Nagashima, Shu Seki, Keisuke Oka, Masateru Taniguchi, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 95, 5, 053105, AMER INST PHYSICS, 2009年08月, [査読有り]
    英語, 研究論文(学術雑誌), Impurity doping on semiconductor nanowires grown by vapor-liquid-solid (VLS) mechanism remains an important challenge. Here we demonstrate the importance of doping dynamics to control the transport properties of Sb-doped SnO2 nanowires. Sb doping decreased the resistivity of SnO2 nanowires down to 10(-3) cm range, while there was the lower bound of resistivity even increasing further the dopant concentration from supplied source. We found that the doping limitation is related to the re-evaporation events of dopant through vapor-solid growth process rather than VLS process. Thus understanding the dopant incorporation dynamics is essential to control the transport properties of SnO2 nanowires by impurity doping.
  • Unipolar resistive switching characteristics of room temperature grown SnO2 thin films
    Kazuki Nagashima, Takeshi Yanagida, Keisuke Oka, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 94, 24, 242902, AMER INST PHYSICS, 2009年06月, [査読有り]
    英語, 研究論文(学術雑誌), The resistive switching characteristics of room temperature grown SnO2 films were investigated by fabricating the metal-oxide-metal sandwich structures. The unipolar operation was found in all devices. Experiments, including the size and material dependencies of the top electrodes and the three terminal device structures, demonstrated the rupture and formation of conducting filaments near the anode. The Ohmic behavior was observed in both on- and off-states when using Au and Ti top electrodes, whereas the Schottky behavior was only found in the off-state for Pt. The analysis on the transport properties indicates the presence of insulative crystalline SnO2 near the anode in the off-state.
  • Nonvolatile Bipolar Resistive Memory Switching in Single Crystalline NiO Heterostructured Nanowires
    Keisuke Oka, Takeshi Yanagida, Kazuki Nagashima, Hidekazu Tanaka, Tomoji Kawai
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 131, 10, 3434, +, AMER CHEMICAL SOC, 2009年03月, [査読有り]
    英語, 研究論文(学術雑誌), We have demonstrated the nonvolatile bipolar resistive memory switching in single crystalline NiO heterostructured nanowires for the first time. The self-assembled NiO nanowires are expected to open up opportunities to explore not only the detailed nanoscate mechanisms in NiO resistive memory switching but also next-generation nanoscate nonvolatile memory devices with the potential for high-density device integration and improved memory characteristics.
  • 酸化物へテロナノワイヤ構造の作製と電気輸送特性
    柳田 剛, 長島 一樹, 岡 敬祐, 川合 知二
    化学工学会 研究発表講演要旨集, 2009, 316, 316, 公益社団法人 化学工学会, 2009年
    日本語
  • 酸化物ナノワイヤ構造体における不純物ドーピング制御
    柳田 剛, Klamchuen Annop, 長島 一樹, 岡 敬祐, 谷口 正輝, 川合 知二, 関 修平
    化学工学会 研究発表講演要旨集, 2009, 458, 458, 公益社団法人 化学工学会, 2009年
    日本語
  • Enhancement of Oxide VLS Growth by Carbon on Substrate Surface
    Takeshi Yanagida, Aurelian Marcu, Hiroaki Matsui, Kazuki Nagashima, Keisuke Oka, Kazumichi Yokota, Masateru Taniguchi, Totnoji Kawai
    JOURNAL OF PHYSICAL CHEMISTRY C, 112, 48, 18923, 18926, AMER CHEMICAL SOC, 2008年12月, [査読有り]
    英語, 研究論文(学術雑誌), Oxide nanowires formed via the vapor-liquid-solid (VLS) mechanism are potential candidates to incorporate the rich functionalities into the nanowire-based devices. However, the complex nature of oxide VLS mechanism has held back the formation of well-defined oxide nanowires. Here we report the enhancement of oxide VLS growth by carbon and discuss the underlying mechanism. In ZnO nanowire growth, the presence of carbon layers predeposited on the Substrate Surface strongly enhances the VLS growth. Spectroscopy analysis demonstrates that the carbon predeposited on the surfaces could only exist at the initial stage of the VLS growth, as also evidenced from the optical quality of the ZnO nanowires. Thus, the existence of carbon at the initial stage of the VLS growth plays an important role on enhancing the oxide VLS growth and might act as a seed material in addition to Au catalyst. Furthermore, the presence of carbon enhances various oxide VLS growths, including SnO(2) and MgO, indicating the universal effect on oxide VLS growth mechanism.
  • Mechanism and control of sidewall growth and catalyst diffusion on oxide nanowire vapor-liquid-solid growth
    Kazuki Nagashima, Takeshi Yanagida, Keisuke Oka, Hidekazu Tanaka, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 93, 15, 153103, AMER INST PHYSICS, 2008年10月, [査読有り]
    英語, 研究論文(学術雑誌), Oxide nanowires formed via the vapor-liquid-solid (VLS) mechanism are attractive building blocks toward nanowire-based electronic devices due to their fascinating physical properties. Although well-defined oxide nanowires are strongly required for the applications, tapering during oxide nanowire VLS growth has been detrimental and uncontrollable. Here we demonstrate the mechanism to control the tapering during oxide VLS growth. Suppressing simultaneously both the oxidization of adatoms at the sidewall and the catalyst diffusion from the tip was found to be essential to avoid the tapering. This mechanism would be universal in various oxide nanowire VLS growths. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2978347]
  • Growth atmosphere dependence of transport properties of NiO epitaxial thin films
    Keisuke Oka, Takeshi Yanagida, Kazuki Nagashima, Hidekazu Tanaka, Tomoji Kawai
    JOURNAL OF APPLIED PHYSICS, 104, 1, 013711, AMER INST PHYSICS, 2008年07月, [査読有り]
    英語, 研究論文(学術雑誌), Recent possible applications in nonvolatile resistive switching memory devices renewed the interests in the transport properties of NiO. The variation on the conductivities of NiO films was reported to strongly affect the resistive switching phenomena. The conduction mechanism of NiO has been interpreted in terms of the bulk p-type conduction mechanism via Ni deficiencies (Ni(1-delta)O). Here we investigate the growth atmosphere dependence on the transport properties of NiO thin films epitaxially grown on MgO (001) substrate. The conductivities of NiO thin films showed completely an opposite tendency compared to the bulk p-type conduction mechanism. Microstructural analysis demonstrates that the conductivity of low temperature grown NiO thin films strongly correlates with tailing the band edge via the deterioration of entire film crystallinity rather than the grain boundaries including second phases. (c) 2008 American Institute of Physics.
  • Mechanism of critical catalyst size effect on MgO nanowire growth by pulsed laser deposition
    Takeshi Yanagida, Kazuki Nagashima, Hidekazu Tanaka, Tomoji Kawai
    JOURNAL OF APPLIED PHYSICS, 104, 1, 016101, AMER INST PHYSICS, 2008年07月, [査読有り]
    英語, 研究論文(学術雑誌), The size controllability of oxide nanowires formed via vapor-liquid-solid (VLS) mechanism is desired for the oxide nanowire-based device applications. However, the complex nature of oxide nanowire VLS growth has held back such size controllability. Here we demonstrate the critical size effect of a Au catalyst on MgO nanowire VLS growth by pulsed laser deposition. The presence of a critical catalyst size was found. Above such critical size, an oxide nanowire VLS growth is no longer feasible. Interestingly, such critical size increased with increasing growth temperature. The mechanism of the critical phenomenon is interpreted in terms of the catalyst size dependence on the amount of adatoms diffused from surroundings into the catalyst. (c) 2008 American Institute of Physics.
  • Crucial role of interdiffusion on magnetic properties of in situ formed MgO/Fe3-delta O4 heterostructured nanowires
    Aurelian Marcu, Takeshi Yanagida, Kazuki Nagashima, Keisuke Oka, Hidekazu Tanaka, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 92, 17, 173119, AMER INST PHYSICS, 2008年04月, [査読有り]
    英語, 研究論文(学術雑誌), Although a heterointerface in oxides plays a crucial role on the properties, such heterointerface effects on oxide nanowires have not been well understood. Here, we demonstrate the crucial role of atomic interdiffusion on the magnetic properties of in situ formed MgO/Fe3-delta O4 heterostructured nanowires. The wide variation of nanowire heterointerfaces was found when varying the growth atmosphere. The occurrence of the interdiffusion and the large interface area of nanowires strongly affect the magnetism via forming mixed spinel structures at the heterointerface. Thus, it is crucial to precisely control the atomic interdiffusion at the heterointerface for the desired properties of heterostructured oxide nanowires. (c) 2008 American Institute of Physics.
  • Effect of the heterointerface on transport properties of in situ formed MgO/titanate heterostructured nanowires
    Kazuki Nagashima, Takeshi Yanagida, Hidekazu Tanaka, Shu Seki, Akinori Saeki, Seiichi Tagawa, Tomoji Kawai
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 130, 15, 5378, 5382, AMER CHEMICAL SOC, 2008年04月, [査読有り]
    英語, 研究論文(学術雑誌), Heterostructured transition metal oxide nanowires are potential candidates to incorporate rich functionalities into nanowire-based devices. Although the oxide heterointerface plays a crucial role in determining the physical properties, the effects of the heterointerface on the oxide nanowire's properties have not been clarified. Here we investigate for the first time the significant role of the heterointerface in determining the transport properties of well-defined MgO/titanate heterostructured nanowires by combining a technique for in situ formation of a oxide heterointerface and microwave conductivity measurement. Variation of the heterointerface strongly affects the nanowire's transport properties due to the crystallinity and the atomic interdiffusion at the oxide heterointerface. Thus, the precise in situ formation of a well-defined heterointerface is crucial to create oxide heterostructured nanowires with the desired transport properties.
  • 酸化物へテロナノワイヤの単一構造体測定法の構築と電気輸送特性
    柳田 剛, 長島 一樹, 岡 敬祐, 谷口 正輝, 田中 秀和, 川合 知二
    化学工学会 研究発表講演要旨集, 2008, 675, 675, 公益社団法人 化学工学会, 2008年
    日本語
  • 極微不揮発性メモリデバイスに向けたMgO/NiOへテロナノワイヤ構造体のIn-situ形成と電気輸送特性評価
    柳田 剛, 岡 敬祐, 長島 一樹, 田中 秀和, 川合 知二, 関 修平
    化学工学会 研究発表講演要旨集, 2008, 676, 676, 公益社団法人 化学工学会, 2008年
    日本語
  • レーザMBE法によるMgOナノワイヤ形成メカニズムと形態制御
    柳田 剛, 長島 一樹, 岡 敬介, 田中 秀和, 川合 知二
    化学工学会 研究発表講演要旨集, 2008, 677, 677, 公益社団法人 化学工学会, 2008年
    日本語
  • 遷移金属酸化物ナノワイヤの電気輸送特性におけるヘテロ界面の影響
    柳田 剛, 長島 一樹, 岡 敬介, 田中 秀和, 川合 知二
    化学工学会 研究発表講演要旨集, 2008, 678, 678, 公益社団法人 化学工学会, 2008年
    日本語
  • Mechanism of catalyst diffusion on magnesium oxide nanowire growth
    Takeshi Yanagida, Kazuki Nagashima, Hidekazu Tanaka, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 91, 6, 061502-061502-3, AMER INST PHYSICS, 2007年08月, [査読有り]
    英語, 研究論文(学術雑誌), In nanowire growth using vapor-liquid-solid (VLS) mechanism, controlling catalyst diffusion has been a key issue since VLS growth is essentially no longer feasible in the absence of catalyst on the tip. Here the authors demonstrate the controllability of catalyst diffusion on MgO nanowire growth by ambient pressure and discuss the underlying physical mechanism. Drastic enhancement of oxide nanowire growth was found when increasing the ambient pressure under oxygen atmosphere, and surprisingly even under argon atmosphere. This indicates that the ambient pressure rather than the amount of ambient oxygen dominates the oxide nanowire growth via suppressing the catalyst diffusion.
  • Effect of ablated particle flux on MgO nanowire growth by pulsed laser deposition
    Aurelian Marcu, Takeshi Yanagida, Kazuki Nagashima, Hidekazu Tanaka, Tomoji Kawai
    JOURNAL OF APPLIED PHYSICS, 102, 1, 016102, AMER INST PHYSICS, 2007年07月, [査読有り]
    英語, 研究論文(学術雑誌), Oxide nanowire growth using a pulsed laser deposition (PLD) is a promising process since this essentially allows incorporating a rich functionality of various transition metal oxides into nanowires via the heterostructures. Here we investigate the effect of ablated particle flux on magnesium oxide nanowire growth by PLD. When varying the distance between the ablated material and the substrate, the small variation in ablated particle flux generated by a different plume expansion time influences mainly the growth rate while keeping the growth regime. However, varying the laser energy changes not only the growth rate but also the growth regime. Below a critical value of the laser energy the surface morphology tends to show an island growth rather than a nanowire growth. We attribute the existence of such a threshold to the desorption process from the catalyst droplet.
  • Transport properties of ZnFe2O4-delta thin films
    Aurelian Marcu, Takeshi Yanagida, Kazuki Nagashima, Hidekazu Tanaka, Tomoji Kawai
    JOURNAL OF APPLIED PHYSICS, 102, 2, 023713, AMER INST PHYSICS, 2007年07月, [査読有り]
    英語, 研究論文(学術雑誌), This study presents an experimental investigation on the transport properties of ZnFe2O4-delta (ZFO) thin films to clarify the ambient atmosphere effects on the transport properties by varying the oxygen pressure and the substrate temperature. Previous investigations have demonstrated the significant role of Fe2+ ion concentration due to oxygen vacancies on the transport properties of ZFO. Our systematic investigation suggests that the electrical transport of ZFO thin films is also strongly influenced by structural disorders and vacancies.
  • Control of magnesium oxide nanowire morphologies by ambient temperature
    Kazuki Nagashima, Takeshi Yanagida, Hidekazu Tanaka, Tomoji Kawai
    APPLIED PHYSICS LETTERS, 90, 23, 233103, AMER INST PHYSICS, 2007年06月, [査読有り]
    英語, 研究論文(学術雑誌), Although controlling morphologies of oxide nanowires formed using vapor-liquid-solid (VLS) mechanism is desired in developing functional oxide-nanowire applications, a comprehensive understanding of the key factors affecting oxide-nanowire VLS growth is still lacking. Here, the authors demonstrate the controllability of magnesium oxide nanowire morphologies by varying the ambient temperature and discuss the underlying mechanism. Decreasing the ambient temperature resulted in shorter, tapered, and square-rod shaped nanowires, whereas increasing the ambient temperature allowed fabricating longer and untapered nanowires. The variation of oxide-nanowire morphologies is interpreted in terms of the competition between the VLS growth and the sidewall growth due to the variation of adatom transport. (c) 2007 American Institute of Physics.
  • Epitaxial growth of MgO nanowires by pulsed laser deposition
    Kazuki Nagashima, Takeshi Yanagida, Hidekazu Tanaka, Tomoji Kawai
    JOURNAL OF APPLIED PHYSICS, 101, 12, 124304, AMER INST PHYSICS, 2007年06月, [査読有り]
    英語, 研究論文(学術雑誌), We fabricated single-crystalline MgO nanowires epitaxially grown on MgO single crystal substrate using the Au catalyst-assisted pulsed laser deposition (PLD). Controlling appropriately the amount of Au catalyst and the substrate temperature was found to be crucial for the MgO nanowire growth using the catalyst-assisted PLD. In addition, (100) oriented MgO nanowires were epitaxially grown on (100), (110), and (111) oriented substrates, allowing the limited growth directions. The possible growth mechanism of MgO nanowires in PLD is discussed. This feasibility of PLD for fabricating MgO nanowires would contribute to incorporating the rich functionalities of various transition metal oxides into nanowires via in situ construction of heterostructures in oxide nanowires. (c) 2007 American Institute of Physics.
  • Interface effect on metal-insulator transition of strained vanadium dioxide ultrathin films
    Kazuki Nagashima, Takeshi Yanagida, Hidekazu Tanaka, Tomoji Kawai
    JOURNAL OF APPLIED PHYSICS, 101, 2, 026103, AMER INST PHYSICS, 2007年01月, [査読有り]
    英語, 研究論文(学術雑誌), The interface effects on the metal-insulator transition (MIT) of strained VO2 ultrathin films grown epitaxially on TiO2 (001) single crystal substrate were investigated. Varying the surface conditions of TiO2 substrate, such as the roughness and the surface reconstructions, produced the remarkable changes in the MIT events of VO2 thin films, including the transition temperature and the abruptness. The presence of the surface reconstructions was found to be detrimental for applying effectively strain effects due to the strain relaxation in the c axis of VO2 thin films. The abrupt MIT in strained VO2 thin films, deposited on the substrate without such detrimental surface reconstructions, was successfully maintained down to around 5 nm film thickness.
  • Stress relaxation effect on transport properties of strained vanadium dioxide epitaxial thin films
    Kazuki Nagashima, Takeshi Yanagida, Hidekazu Tanaka, Tomoji Kawai
    PHYSICAL REVIEW B, 74, 17, 172106, AMERICAN PHYSICAL SOC, 2006年11月, [査読有り]
    英語, 研究論文(学術雑誌), A stress relaxation effect on the transport properties of strained vanadium dioxide epitaxial thin films grown on TiO2 (001) single crystal was investigated. When varying the film thickness ranging from 10 to 30 nm, there were no significant changes on the crystal structures identified by x-ray diffraction, i.e., no observable stress relaxation effects. On the other hand, increasing the film thickness resulted in the drastic changes on the transport properties including emerging the multisteps of the metal-insulator transition and also increasing the resistivity. The discrepancy between the observed crystal structure and the transport properties was related to the presence of the nanoscale line cracks due to thermal stress. Thus controlling thermal stress relaxation rather than the stress due to the lattice mismatch is critical to investigate the intrinsic nature on the transport properties of strained vanadium dioxide epitaxial thin films.
  • Influence of ambient atmosphere on metal-insulator transition of strained vanadium dioxide ultrathin films
    Kazuki Nagashima, Takeshi Yanagida, Hidekazu Tanaka, Tomoji Kawai
    JOURNAL OF APPLIED PHYSICS, 100, 6, 063714, AMER INST PHYSICS, 2006年09月, [査読有り]
    英語, 研究論文(学術雑誌), The effect of ambient atmosphere on metal-to-insulator transition (MIT) in strained vanadium dioxide (VO2) ultrathin films (7-8 nm) grown epitaxially on TiO2 (001) single crystal substrate by pulsed laser deposition was investigated by varying the ambient oxygen pressure and substrate temperature with the intention being to control arbitrarily the MIT events of strained VO2 ultrathin films, including the MIT temperature and the resistivity change. When reducing the ambient oxygen pressure, the MIT temperature remained almost constant, whereas the change of resistivity during MIT tended to be smaller. Contrary, varying the substrate temperature resulted in the variation of the MIT temperature with keeping the abruptness of transition. The lower the substrate temperature, the lower the MIT temperature, and in addition the MIT temperature similar to 290 K with keeping the abrupt change of resistivity is found to be the lowest compared with previously reported values. The reduction of the MIT temperature was found to correlate with shortening c-axis length when decreasing the substrate temperature, indicating the significant strain effects. Thus these results highlight that controlling appropriately the ambient atmosphere enables us to modulate arbitrarily the MIT events of strained VO2 thin films near room temperature. (c) 2006 American Institute of Physics.

その他活動・業績

書籍等出版物

  • Magnetic Nano- and Microwires, Design, Synthesis, Properties and Applications               
    Kazuki Nagashima, Takeshi Yanagida, Ch16: Oxide nanowires for non-volatile memory applications pp.489-524
    Woodhead Publishing, 2015年05月, [分担執筆]

所属学協会

  • Material Research Society               
  • ナノ学会               
  • 粉体工学会               
  • 化学工学会               
  • 応用物理学会               

共同研究・競争的資金等の研究課題

  • 融合型電子材料ナノワイヤのマクロスケール機能開拓
    科学研究費助成事業
    2023年04月01日 - 2027年03月31日
    石川 史太郎, 村山 明宏, 長島 一樹
    日本学術振興会, 基盤研究(A), 北海道大学, 23H00250
  • 生体の匂い情報処理システムを模倣した新しい原理の人工嗅覚センサ
    科学研究費助成事業
    2022年04月01日 - 2025年03月31日
    長島 一樹
    日本学術振興会, 基盤研究(B), 東京大学, 22H01903
  • 半導体・酸化物複合ナノワイヤによる光・電子・スピン工学の融合
    科学研究費助成事業
    2019年04月01日 - 2023年03月31日
    石川 史太郎, 村山 明宏, 長島 一樹
    本研究では、「半導体・酸化物複合ナノワイヤ」の高品質合成とその応用で光・電子・スピンを操作した新しい学術・工学を開拓する。化合物半導体の高い電子・光物性と金属酸化物の多様で安定した機能が協働する高機能ナノ材料を提案し、これを用いたフォトニクス・エレクトロニクス・スピントロニクス融合型ナノテクノロジーの創出を目指す。本年度には、研究の基盤となるナノワイヤ試料合成技術の確立と高度化に取り組み、以下に挙げる成果を得ることができた。
    まず、酸化物を有するGaAs/AlGaOxヘテロ構造ナノワイヤの大面積化とそれから得られる白色光の特性把握に取り組んだ。GaAs/高いAl組成AlGaAsヘテロ構造ナノワイヤの大容量成長とそれに対する適切な酸化条件を抽出することで、紫外域のLED励起で目視可能な白色蛍光体を得ることができ、その状況をスマートフォンのカメラでも観察記録することに成功した。
    ナノワイヤ試料全体の光学特性、構造特性改善のために、加工基板を用いた選択成長を行った。その結果、従来と3倍を超える広いV属/III族元素供給比でのナノワイヤ結晶成長が可能であり、適切なAs供給量を用いることで高精度の構造制御と発光特性改善が得られることが見出された。
    通信光源材料、スピンフィルター材料と期待できるGaNAsBi系ナノワイヤの成長では、低温350℃領域で適切な成長条件を探求することで、整ったGaAs/GaNAsBi/GaAsコアーマルチシェルナノワイヤ構造の形成とそこから室温で通信帯域、波長1.2μmの発光を観察することに成功した。
    日本学術振興会, 基盤研究(A), 19H00855
  • 多元素機能傾斜無機分子認識ナノ薄膜による高堅牢性人工嗅覚センサの創成
    科学研究費助成事業
    2020年04月24日 - 2022年03月31日
    長島 一樹, SAMRANSUKSAMER BENJARONG
    本研究では、1)分子認識無機材料を複数傾斜堆積させ形成する多元素機能傾斜ナノ薄膜を利用して生体の嗅覚システムの多様性に倣った堅牢な集積化人工嗅覚センサを構築し、2)本センサデバイスを介して得られる膨大な分子センシングデータを人工知能により解析することで生体ガスセンシングによる生体情報のモニタリング機能を実証することを目的としている。本年度は前年度に作製した金属酸化物ナノ薄膜センサにおいて課題となっていた分子センシングにおける電流応答性・応答速度の改善へ向けて、室温アモルファス状態で基板上に堆積された金属酸化物ナノ薄膜のアニール温度/膜厚を変調することによりナノ結晶化プロセスを精密制御に取り組んだ。その結果、結晶粒界の形状と電流応答性・応答速度との相関性を明らかにすると共に劇的な電流応答性の向上に成功した。更に本年度は膨大なデータ群を高速分析するために、画像処理及び機械学習を活用したデータ分析法を構築した。また、構築したデータ分析法を活用して生体呼気分析・センシングにより得られたデータの多次元解析を行い、生体呼気による化学情報を介した個人認証(20名対象)の実証に成功した。
    日本学術振興会, 特別研究員奨励費, 東京大学, 20F20048
  • 超多チャンネルセンサアレイによる多成分同時分子識別デバイスの創製               
    国際共同研究強化(B)
    2018年10月 - 2021年03月
    長島 一樹
    (独) 日本学術振興会, 研究代表者, 競争的資金
  • 高堅牢性分子指紋ナノワイヤの創成及び革新的分子識別法の開発               
    科学研究費補助金 基盤研究(B)
    2018年04月 - 2021年03月
    長島 一樹
    (独) 日本学術振興会, 研究代表者, 競争的資金
  • セルロースナノペーパーを用いた不揮発性メモリの創製
    科学研究費助成事業
    2014年05月30日 - 2019年03月31日
    能木 雅也, 柳田 剛, 古賀 大尚, 長島 一樹
    電気抵抗変化現象を利用したペーパーメモリの開発を行うため、セルロースナノファイバーからなるセルロースナノペーパーを中心に研究を行った。ナノペーパーにおける、原料・プロセス・内部構造メカニズムという多角的な視点から学術的知見を深めた。それらの知見により、セルロースナノペーパーの性能を向上させ、2種類の不揮発性ペーパーメモリを開発した。また、不揮発性メモリ現象のメカニズム解明から得た知見を利用し、無機ナノワイヤ材料と複合化した透明導電膜や分子センサといったフレキブルペーパーデバイスの開発も行った。
    日本学術振興会, 基盤研究(S), 大阪大学, 26220908
  • 金属酸化物単結晶ナノワイヤの界面設計による機能創出
    科学研究費助成事業
    2015年04月01日 - 2018年03月31日
    柳田 剛, 長島 一樹, 竹田 精治, 内田 建
    1次元単結晶ナノワイヤの研究は、マヨラナ準粒子に代表される基礎学術的なものから、優れた電子輸送特性と巨大表面積を活用したデバイス応用研究に至るまで多岐に渡る。しかし、機能の宝庫である金属酸化物ナノワイヤでは、ナノワイヤ界面(表面、ナノワイヤ-電極界面)の設計指針が欠如しており、機能発現及びデバイス応用展開における本質的な問題となっていた。本研究では、単結晶金属酸化物ナノワイヤにおいて界面が与える電子・熱物性への影響を明らかにし、これを制御する新たな設計指針構築に成功した。本知見により、金属酸化物ナノワイヤ本来の機能物性抽出、及び金属酸化物ナノワイヤによる革新的機能デバイス創出が期待される。
    日本学術振興会, 基盤研究(B), 九州大学, 15H03528
  • 酸化物ナノ機能物性の抽出を目指した絶縁性単結晶酸化物ナノワイヤの創成               
    科学研究費補助金 若手研究(A)
    2014年04月 - 2018年03月
    長島 一樹
    (独) 日本学術振興会, 研究代表者, 競争的資金
  • ナノチャネル電極デバイスによる長鎖DNAのエピジェネティック物性の超高速検出
    科学研究費助成事業
    2013年04月01日 - 2016年03月31日
    川合 知二, 長島 一樹, 田中 裕行
    自己組織化プロセスにより形成するナノロッド構造と微細加工技術を駆使したチャネル構造を有機的に融合させることに成功した。長鎖DNA分子を伸長化するためには、①ランダムコイル状の長鎖DNA分子がコンフォメーションを変えながらナノ流路に侵入するプロセスAと②その後にDNAの持続長(50nm 程度)以下のナノ流路空間に閉じ込めるプロセスBを制御する必要がある。本研究において検出時間分解能を決定するプロセスAの侵入速度を制御するためには、ナノ流路の直前で長鎖DNA分子がある程度伸長されていることが重要であることが分かった。そこでプロセスAを制御するために、DNAの持続長以下のサイズの自己組織化ナノロッド構造をナノチャネル前に配置し、Hairpin Collision と呼ばれるDNAが自身の持続長以下のナノ構造体に引っ掛かることで伸長されるダイナミクスを利用した。次いで、プロセスBを設計するために、これまでに我々のグループで構築してきた微細加工技術を駆使してチャネル幅50nm 以下のナノチャネル構造を創製した。本研究により、従来技術では展開することが困難であった長鎖DNA分子を短時間で伸長・分離・検出することに成功した。
    日本学術振興会, 基盤研究(A), 大阪大学, 25246014
  • 自己組織化酸化物1次元ナノ構造体による酸化還元ナノスケールスイッチング素子の 創成               
    科学研究費補助金 挑戦的萌芽研究
    2012年04月 - 2015年03月
    長島 一樹
    (独) 日本学術振興会, 研究代表者, 競争的資金
  • 構造制御されたナノワイヤヘテロ構造体の創成と室温動作酸化物ナノデバイスへの展開               
    特別研究員奨励費 (DC1)
    2008年04月 - 2010年03月
    長島 一樹
    短縮修了のため途中辞退
    (独) 日本学術振興会, 研究代表者, 競争的資金

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