| 1. |
J. Liu, H. Zeng, G. Zhang, W. Li, K. Nagashima, T. Takahashi, T. Hosomi, W. Tanaka,M. Kanai and T. Yanagida, Edge-Topological Regulation for in Situ Fabrication of Bridging Nanosensors, Nano Letters, DOI:10.1021/acs.nanolett.1c04600, 22, 6, 2567-2577, 2022.02, In situ fabrication of well-defined bridging nanostructures is an interesting and unique approach to three-dimensionally design nanosensor structures, which are hardly attainable by other methods. Here, we demonstrate the significant effect of edge-topological regulation on in situ fabrication of ZnO bridging nanosensors. When employing seed layers with a sharp edge, which is a well-defined structure in conventional lithography, the bridging angles and electrical resistances between two opposing electrodes were randomly distributed. The stochastic nature of bridging growth direction at the sharp edges inherently causes such unintentional variation of structural and electrical properties. We propose an edgeless seed layer structure using a two-layers resist method to solve the above uncontrollability of bridging nanosensors. Such bridging nanosensors not only substantially improved the uniformity of structural and electrical properties between two
opposing electrodes but also significantly enhanced the sensing responses for NO2 with the smaller variance and the lower limit of detection via in situ controlled electrical contacts.. |
| 2. |
T. Yasui, P. Paisrisarn, T. Yanagida, Y. Konakade, Y. Nakamura, K. Nagashima, M. Musa, I. A. Thiodorus, H. Takahashi, T. Naganawa, T. Shimada, N. Kaji, T. Ochiya, T. Kawai and Y. Baba, Molecular Profiling of Extracellular Vesicles via Charge-based Isolation using Oxide Nanowire Microfluidics, Biosensors and Bioelectronics, 10.1016/j.bios.2021.113589, 194, 113589-113589, 2021.12, 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.. |
| 3. |
W.Li, K.Nagashima, T.Hosomi, C.Wang, Y.Hanai, A.Nakao, A.Shunori, J.Liu, G. Zhang, T.Takahashi, W.Tanaka, M.Kanai and T. Yanagida, Mechanistic Approach for Long-Term Stability of a Polyethylene
Glycol−Carbon Black Nanocomposite Sensor, ACS Sensors, 10.1021/acssensors.1c01875, 7, 1, 151-158, 2021.11, Polymer–carbon nanocomposite sensor is a promising molecular sensing device for electronic nose (e-nose) due to its printability, variety of polymer materials, and low operation temperature; however, the lack of stability in an air environment has been an inevitable issue. Here, we demonstrate a design concept for realizing long-term stability in a polyethylene glycol (PEG)–carbon black (CB) nanocomposite sensor by understanding the underlying phenomena that cause sensor degradation. Comparison of the sensing properties and infrared spectroscopy on the same device revealed that the oxidation-induced consumption of PEG is a crucial factor for the sensor degradation. According to the mechanism, we introduced an antioxidizing agent (i.e., ascorbic acid) into the PEG–CB nanocomposite sensor to suppress the PEG oxidation and successfully demonstrated the long-term stability of sensing properties under an air environment for 30 days, which had been difficult in conventional polymer–carbon nanocomposite sensors.. |
| 4. |
C.Jirayupat, K.Nagashima, T.Hosomi, T.Takahashi, W.Tanaka, B.Samransuksamer, G.Zhang, J.Liu, M.Kanai and T. Yanagida, Image Processing and Machine Learning for Automated Identification of Chemo/Bio-markers in Chromatography-Mass Spectrometry, Analytical Chemistry, 10.1021/acs.analchem.1c03163, 93, 44, 14708-14715, 2021.10, We present a method named NPFimg, which
automatically identifies multivariate chemo-/biomarker features
of analytes in chromatography−mass spectrometry (MS) data by
combining image processing and machine learning. NPFimg
processes a two-dimensional MS map (m/z vs retention time) to
discriminate analytes and identify and visualize the marker features.
Our approach allows us to comprehensively characterize the
signals in MS data without the conventional peak picking process,
which suffers from false peak detections. The feasibility of marker
identification is successfully demonstrated in case studies of aroma
odor and human breath on gas chromatography−mass spectrometry (GC−MS) even at the parts per billion level. Comparison with the widely used XCMS shows the excellent reliability of NPFimg,
in that it has lower error rates of signal acquisition and marker identification. In addition, we show the potential applicability of
NPFimg to the untargeted metabolomics of human breath. While this study shows the limited applications, NPFimg is potentially
applicable to data processing in diverse metabolomics/chemometrics using GC−MS and liquid chromatography−MS. NPFimg is
available as open source on GitHub (http://github.com/poomcj/NPFimg) under the MIT license.. |
| 5. |
G. Zhang, H. Zeng, J. Liu, K. Nagashima, T. Takahashi, T. Hosomi, W. Tanaka and T. Yanagida, Nanowire-Based Sensor Electronics for Chemical and Biological Applications, Analyst, 10.1039/D1AN01096D, 146, 6684-6725, 2021.09. |
| 6. |
X. Zhao, K. Nagashima, G. Zhang,T. Hosomi, H. Yoshida, Y. Akihiro, M. Kanai, W. Mizukami, Z. Zhu, T. Takahashi, M. Suzuki, B. Samransuksamer, G. Meng, T. Yasui, Y. Aoki, Y. Baba and T. Yanagida, Synthesis of Monodispersedly Sized ZnO Nanowires from Randomly Sized Seeds, Nano Letters, 10.1021/acs.nanolett.9b04367, 20, 599-605, 2020.04, 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.. |
| 7. |
Chen Wang, Takuro Hosomi, Kazuki Nagashima, Tsunaki Takahashi, Guozhu Zhang, Masaki Kanai, Hao Zeng, Wataru Mizukami, Nobutaka Shioya, Takafumi Shimoaka, Takehiro Tamaoka, Hideto Yoshida, Hideto Yoshida
Hideto Yoshida, Seiji Takeda, TakaoYasui, Yoshinobu Baba, Yuriko Aoki, Jun Terao, Takeshi Hasegawa, Takeshi Yanagida, Rational Method of Monitoring Molecular Transformations on Metal-Oxide Nanowire Surfaces, Nano Letters, org/10.1021/acs.nanolett.8b05180, 19, 4, 2443-2449, 2019.03, 金属酸化物ナノワイヤは熱・化学的安定性に優れたナノ材料であり、次世代IoT向け分子認識センサの有望材料として注目を集めているが、希薄な揮発性分子と金属酸化物ナノワイヤ表面との相互作用を解析・評価することは困難であり、分子認識センサの機能設計における障壁となっていた。本研究では基板上に1方向に配向制御した単結晶酸化亜鉛ナノワイヤアレイを構築し、その規定された巨大ナノ結晶表面上で生じる分子の吸着・化学変化・脱離現象を各種高感度解析法（ガスクロマトグラフ質量分析・角度可変偏光赤外分光法）により評価することで、肺がんマーカー分子であるノナナールの二量化反応、及び酸化反応についてその反応経路と共に明らかにすることに成功した。更に熱処理による酸化亜鉛ナノワイヤの表面特性変調を行うことで各種反応を任意に制御できることが明らかとなった。本研究は、金属酸化物ナノワイヤによる分子認識センサの機能向上、設計に資する重要な知見であり、本論文で提案したアプローチにより、今後多種多様な揮発性分子群のセンサ表面上での振る舞いが解明されていくと期待される。. |
| 8. |
H. Anzai, T. Takahashi, M. Suzuki, M. Kanai, G. Zhang, T. Hosomi, T. Seki, . Nagashima, N. Shibata and T. Yanagida,, Unusual Oxygen Partial Pressure Dependence of Electrical Transport of Single-Crystalline Metal Oxide Nanowires Grown by the Vapor–Liquid–Solid Process, Nano Letters, org/10.1021/acs.nanolett.8b04668, 19, 3, 1675-1681, 2019.03, 単結晶金属酸化物ナノワイヤは金属や半導体など材料系には見られない多彩な機能物性を示す興味深いナノ材料群である。Vapor-Liquid-Solid法は高結晶性のナノワイヤ構造体を構築可能な方法論であるが、本手法を用いて作製された単結晶金属酸化物ナノワイヤは大きなバンドギャップを有する絶縁体であるにも関わらず、結晶欠陥に由来する「意図しないドーピング」により高い電気伝導性が報告されており、ナノ機能物性抽出・変調へ向けて長年の技術的課題となっていた。本研究では、Vapor-Liquid-Solid成長において金属酸化物ナノワイヤの構成元素である酸素の供給フラックス（酸素圧）を変調させた際に、電気伝導性において異常な酸素圧依存性が観測された。電気伝導性及び化学組成の空間分布評価により、本依存性が気固界面及び液固界面といった競合する２つの結晶成長界面における結晶の本質的な差異に起因することを明らかにした。更に、上記実験結果に基づいて構築した1次元結晶成長モデル（分子動力学シミュレーション）に基づいて界面選択的結晶成長を行うことにより、金属酸化物ナノワイヤの超高結晶化に成功した。. |
