Tokeshi Manabu

Faculty of Engineering Applied Chemistry Chemistry of Functional MoleculesProfessor
Last Updated :2025/12/04

■Researcher basic information

Degree

  • Ph.D., Kyushu University, Mar. 1997

Researchmap personal page

Research Field

  • Nanotechnology/Materials, Analytical chemistry
  • Nanotechnology/Materials, Nano/micro-systems
  • Nanotechnology/Materials, Nanomaterials

Educational Organization

■Career

Career

  • Jun. 2015 - Present
    Hokkaido University, Division of Applied Chemisty, Faculty of Engineering, Professor
  • Apr. 2014 - Present
    Nagoya University, Institute of Innovative for Future Society, Visiting Professor
  • Dec. 2013 - Present
    Nagoya University, Innovative Research Center for Preventive Medical Engineering, Visiting Professor
  • Jan. 2018 - Jan. 2023
    Northwest Univeristy, Visiting Professor
  • Mar. 2019 - Mar. 2022
    Obihiro University of Agriculture and Veterinary Medicine, National Research Center for Protozoan Diseases, 共同研究員
  • Apr. 2014 - Mar. 2019
    Nagoya University, ImPACT Research Center for Advanced Nanobiodevices, Visiting Professor
  • Apr. 2010 - Mar. 2016
    愛知県「知の拠点」重点プロジェクト(兼任), 研究員
  • Nov. 2011 - May 2015
    Hokkaido University Faculty of Engineering, Division of Biotechnology and Macromolecular Chemistry, Professor
  • Nov. 2011 - Mar. 2014
    Nagoya University, FIRST Research Center for Innovative Nanobiodevice, 客員教授
  • Sep. 2011 - Feb. 2012
    Karolinska Institutet, 客員研究員
  • Jan. 2011 - Oct. 2011
    Nagoya University, FIRST Research Center for Innovative Nanobiodevice, Division of Single Molecule Device Research, 部門長
  • Dec. 2005 - Oct. 2011
    Nagoya University, Graduate School of Engineering, Graduate School of Engineering
  • 2004 - 2009
    Kanagawa Academy of Science and Technology, 非常勤研究員(兼任)
  • 2007 - 2008
    愛知県産業技術研究所 客員研究員
  • 2004 - 2005
    Institute of Microchemical Technology
  • 2005
    Institute of Microchemical Technology
  • 2004
    Kanagawa Academy of Science and Technology
  • 1999 - 2003
    Kanagawa Academy of Science and Technology
  • 1998 - 1999
    Kanagawa Academy of Science and Technology
  • 1997 - 1998
    日本学術振興会 特別研究員(PD)
  • 1996 - 1997
    日本学術振興会 特別研究員(DC)

Committee Memberships

  • Apr. 2021 - Present
    日本分光学会, 北海道支部支部長, Society
  • Apr. 2021 - Present
    The Chemical Society of Japan, Hokkaido branch secretary, Society
  • May 2020 - Present
    Society for Chemistry and Micro-Nano Systems, Auditor, Society
  • Mar. 2014 - Present
    日本分析化学会, 北海道支部幹事, Society
  • Apr. 2018 - Apr. 2024
    The Asahi Glass Foundation, Research Grant Selection Committee, Others
  • Apr. 2020 - Mar. 2024
    文部科学省, 科学官, Government
  • May 2017 - Mar. 2023
    Japan Science and Technology Agency, PRESTO Research Area Advisor, Government
  • Apr. 2017 - Mar. 2021
    日本分析化学会, 北海道支部副支部長, Society
  • Apr. 2008 - Mar. 2021
    日本学術振興会, 未踏・ナノバイオテクノロジー第151委員会ナノバイオフュージョン分科会企画委員, Society
  • 2015 - Oct. 2020
    The Chemical and Biological Microsystems Society (CBMS), Director, Society
  • May 2018 - May 2020
    化学とマイクロ・ナノシステム学会, 会長, Society
  • Apr. 2010 - May 2020
    化学とマイクロ・ナノシステム学会, 理事, Society
  • Oct. 2017 - Sep. 2019
    電気学会, C部門バイオメディカル・フォトニクス先端技術の応用に向けた協同研究委員会委員, Society
  • Jun. 2017 - Aug. 2018
    文部科学省, 科学技術・学術審議会専門委員
  • Apr. 2016 - Apr. 2018
    化学とマイクロ・ナノシステム学会, 副会長, Society
  • Oct. 2015 - Sep. 2017
    電気学会, C部門バイオメディカル・フォトニクス先端技術協同研究委員会委員, Society
  • Oct. 2013 - Sep. 2015
    電気学会, C部門バイオメディカル・オプティクス応用技術協同研究委員会委員, Society
  • Apr. 2010 - Mar. 2015
    日本ナノメディシン交流協会, 理事, Society
  • Oct. 2011 - Sep. 2013
    電気学会, C部門バイオメディカル・フォトニクス応用技術協同研究委員会委員, Society
  • Jan. 2011 - Oct. 2011
    名古屋大学革新ナノバイオデバイス研究センター, 運営委員, Others
  • Oct. 2009 - Sep. 2011
    電気学会, C部門バイオメディカル・フォトニクス応用技術調査専門委員会委員, Society
  • Apr. 2009 - Mar. 2011
    電気学会, E准部門バイオマイクロシステム技術委員会細胞マイクロシステム技術調査専門委員会委員長, Society
  • Apr. 2008 - Mar. 2011
    日本分析化学会, 中部支部常任幹事, Society
  • Apr. 2007 - Oct. 2010
    International Conference on Miniaturization Systems for Chemistry and Life Sciences (MicroTAS), Technical Program Committee Member, Society
  • Nov. 2008 - Mar. 2010
    日本化学会, 東海支部代議員, Society
  • 2007 - 2009
    International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS), Technical Program Committee Member, Others
  • Apr. 2007 - Mar. 2008
    電気学会, C部門バイオメディカル・フォトニクス先端技術調査専門委員会委員, Society
  • Apr. 2007 - Mar. 2008
    日本分析化学会, 中部支部幹事, Society
  • Dec. 2005 - Nov. 2007
    電気学会, E准部門バイオマイクロシステム技術委員会バイオ極限計測マイクロシステム技術調査専門委員会幹事, Society
  • Jun. 2005 - Mar. 2006
    日本規格協会, JIS K0212改正原案作成委員会幹事, Society
  • Mar. 2004 - Nov. 2005
    日本分析化学会, 関東支部幹事, Society

■Research activity information

Awards

  • Jul. 2025, Royal Society of Chemistry, Nanoscale Advances Paper Prize Award               
    Runner-Up Paper
    Masatoshi Maeki;Niko Kimura;Yuto Okada;Kazuki Shimizu;Kana Shibata;Yusuke Miyazaki;Akihiko Ishida;Kento Yonezawa;Nobutaka Shimizu;Wataru Shinoda;Manabu Tokeshi
  • Oct. 2021, Network Joint Research Center for Materials and Devices, Material / Device Joint Research Award               
    蛍光偏光イムノアッセイ法による抗体検出法
    Manabu Tokeshi;Keine Nishiyama;Kazuki Takahashi;Akihide Hibara
  • Feb. 2021, 北海道大学, 教育研究総長表彰               
    渡慶次学
  • Apr. 2019, Royal Society of Chemistry, Fellow(FRSC)               
    TOKESHI Manabu
  • Sep. 2018, 日本分析化学会, 学会賞               
    渡慶次 学
  • Oct. 2011, 堀場製作所, 堀場雅夫賞               
    渡慶次 学
  • Oct. 2007, Pioneers of Miniaturisation Prize               
    Japan
  • Jul. 2007, 可視化情報学会学会賞(論文賞)               
    Japan
  • May 2007, CHEMINAS奨励賞               
    Japan

Papers

  • Examining the Impact of Storage Conditions on the Stability of a Liquid Formulation of mRNA-Loaded Lipid Nanoparticles
    Mina Sato, Eleni Samaridou, Moritz Beck-Broichsitter, Masatoshi Maeki, Shunsuke Kita, Manabu Tokeshi, Katsumi Maenaka, Hideyoshi Harashima, Yusuke Sato
    Pharmaceutics, 17, 9, 1194, 1194, MDPI AG, 14 Sep. 2025, [Peer-reviewed]
    English, Scientific journal, Background/Objectives: This study investigated the effect of storage conditions on mRNA-LNPs in situ via identification of the formulation traits necessary for improving storage stability. Methods: We synthesized an ionizable lipid, namely TOT-28, which has a hydrolysis-susceptible ester bond in its hydrophilic head group that allows it to act as an indicator of the hydrophilic environment within the mRNA-LNPs. LNPs were stored either at 4 or 25 °C for up to 8 weeks to investigate the effect of pH and temperature on ester hydrolysis, internal mRNA integrity, physicochemical properties of the LNPs, and mRNA gene expression. Results: The results indicate that, at 25 °C, a lower buffer pH increases ester hydrolysis, whereas an opposite trend slightly occurs in ester hydrolysis with storage at 4 °C. We also found that TOT-28-based LNPs were less hydrated and microviscosity was higher at 4 °C compared with storage temperature at 25 °C. Therefore, TOT-28-based LNPs seem less sensitive to external buffer solutions because of a higher-order structure when stored at lower temperatures. In addition, we found that LNPs with different ionizable lipid structures exhibit distinct responses to pH changes at specific storage temperatures. Conclusions: Our findings provide novel insights into the appropriate conditions for long-term storage of the mRNA-LNPs as a liquid formulation.
  • Development of Paper-based Microfluidic Devices for the Detection of Cannabis Components
    Akihiko Ishida, Nozomi Nagase, Chikako Takei, Kayo Nakamura, Hideyo Takahashi, Hiroko Abe, Manabu Tokeshi
    IEEJ Transactions on Sensors and Micromachines, 145, 9, 195, 200, Institute of Electrical Engineers of Japan (IEE Japan), 01 Sep. 2025, [Peer-reviewed], [Last author]
    Japanese, Scientific journal, 50144367
  • Paper discs in a 3D printed microplate hybrid microfluidic device for low-cost, rapid, and ultrasensitive paper-based bioluminescence detection of human epidermal growth factor receptor 2 (HER2) breast cancer biomarker
    Ahmed A. Shalaby, Asmaa Salah, Akihiko Ishida, Masatoshi Maeki, Manabu Tokeshi
    Biosensors and Bioelectronics: X, 24, 100621, 100621, Elsevier BV, Aug. 2025, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Isolating and Determining the Structures of Colored Products from the Reactions of Cannabinoids with Fast Blue RR
    Kayo Nakamura, Hikari Nishiguchi, Ryosuke Arai, Riho Hamajima, Hiroko Abe, Akihiko Ishida, Manabu Tokeshi, Kyohei Higashi, Akiyoshi Saitoh, Hideyo Takahashi
    Molecules, 30, 3462, Aug. 2025, [Peer-reviewed]
    English, Scientific journal
  • Lipid nanoparticle delivery of the CRISPR/Cas9 system directly into the mitochondria of cells carrying m.7778G>T mutation in MtDNA (mt-Atp8)
    Kaede Norota, Sen Ishizuka, Misa Hirose, Yusuke Sato, Masatoshi Maeki, Manabu Tokeshi, Saleh M. Ibrahim, Hideyoshi Harashima, Yuma Yamada
    Scientific Reports, 15, 1, Springer Science and Business Media LLC, 19 Jun. 2025, [Peer-reviewed]
    English, Scientific journal
  • Microfluidic Production of Exosome-Mimicking Lipid Nanoparticles for Enhanced RNA Delivery: Role of Exosomal Proteins
    Masatoshi Maeki, Ayuka Niwa, Shota Oyama, Kyoko Aratani, Rina Ito, Yuichi Suzuki, Yusuke Sato, Akihiko Ishida, Hideyoshi Harashima, Manabu Tokeshi
    ACS Applied Materials & Interfaces, 17, 29, 41666, 41679, American Chemical Society (ACS), 16 Jun. 2025, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Conjugated Polymer Nanoparticles and Thin Films of Defect-Free Cyclic P3HT: Effects of Polymer Topology on the Nanostructure
    Tomohisa Watanabe, Masatoshi Maeki, Manabu Tokeshi, Tianle Gao, Feng Li, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Takuya Yamamoto
    Molecules, 30, 2490, Jun. 2025, [Peer-reviewed]
    English, Scientific journal
  • Unraveling the Molecular Mechanism of Transient Multilamellar Formation in Ethanol-Modified Vesicle Solutions
    Kana Shibata, Masatoshi Maeki, Manabu Tokeshi, Wataru Shinoda
    Langmuir, 41, 21, 13372, 13380, American Chemical Society (ACS), 20 May 2025, [Peer-reviewed]
    English, Scientific journal
  • Microfluidic technologies for protein crystallography: advances and applications
    Masatoshi Maeki, Akihiko Ishida, Manabu Tokeshi
    Analytical Sciences, 41, 8, 1203, 1211, Springer Science and Business Media LLC, 21 Apr. 2025, [Peer-reviewed], [Invited], [Last author]
    English, Scientific journal
  • Microfluidic paper-based analytical devices: proven applications and future prospects in therapeutic drug monitoring, homeland security, and chemical education
    Manabu Tokeshi
    Analytical Sciences, 41, 8, 1157, 1168, Springer Science and Business Media LLC, 19 Apr. 2025, [Peer-reviewed], [Invited], [Lead author, Corresponding author]
    English, Scientific journal, 45205131
  • Splenic B cell-targeting lipid nanoparticles for safe and effective mRNA vaccine delivery.
    Yuichi Suzuki, Mai Yakuwa, Mina Sato, Eleni Samaridou, Moritz Beck-Broichsitter, Masatoshi Maeki, Manabu Tokeshi, Yuma Yamada, Hideyoshi Harashima, Yusuke Sato
    Journal of Controlled Release, 382, 113687, 113687, 03 Apr. 2025, [Peer-reviewed], [Corresponding author], [International Magazine]
    English, Scientific journal, mRNA-loaded lipid nanoparticles (LNPs) have emerged as a potent and versatile platform that underpins the success of mRNA vaccines, but guidelines for designing safe and effective formulations with minimal off-target effects remain unclear. In this study, we focused on a rational design for a novel ionizable lipid library that is based on ionizable tri-oleoyl-tris (iTOT) compounds with a high yield via a simple 2-step synthesis. To further enhance the efficacy and safety of this potent library for vaccine applications, we identified the optimal composition for a vaccine by focusing on the molar ratio of specific lipid excipients in the formulation. This composition brought about a shift in delivery to the spleen, and the LNP formulation, which contained 15 mol% DSPC (15%DSPC-LNPs), was thoroughly taken up by both B cells and other splenic immune cells. This formulation requires neither additional lipid components nor targeting ligand modifications, and it is accompanied by antigen-specific cytotoxic T lymphocyte responses. The rigid, hydrophobic, and charge-neutral surface of 15%DSPC-LNPs minimizes apolipoprotein E-dependent hepatic uptake and maximizes complement receptor-mediated B-cell targeting. Furthermore, as an intramuscularly administered vaccine, 15%DSPC-LNPs induce antigen-specific immune responses and, importantly, results in significantly lower levels of hepatotoxicity compared with that of the mRNA vaccine formulations currently being marketed. In summary, this study demonstrated how the passive targeting of mRNA-LNPs to organs and cells could be regulated by designing novel ionizable lipids combined with adjusting the relative proportions of lipid components. The results of this study also emphasize how selective mRNA delivery to the spleen could avoid the liver, which highlights a promising strategy for the development of safe and effective vaccines.
  • 2-Propanol Suspension Method to Increase Acetylcholinesterase and Flow Stability on μPADs
    Akinori Yamaguchi, Shota Oyama, Akihiko Ishida, Takanori Enomoto, Nobuyuki Sanari, Hajime Miyaguchi, Manabu Tokeshi
    ACS Applied Bio Materials, 8, 2, 1699, 1706, American Chemical Society (ACS), 24 Jan. 2025, [Peer-reviewed], [Last author]
    English, Scientific journal
  • Marginal-zone B cells as promising targets of an mRNA-loaded, lipid-nanoparticle cancer vaccine
    Yuichi Suzuki, Mai Yakuwa, Mina Sato, Eleni Samaridou, Moritz Beck-Broichsitter, Masatoshi Maeki, Manabu Tokeshi, Yuma Yamada, Hideyoshi Harashima, Yusuke Sato
    Next Nanotechnology, 8, 100154, 100154, Elsevier BV, 2025, [Peer-reviewed]
    English, Scientific journal
  • Straightforward high-temperature antibody immobilization for rapid and simple microfluidic paper-based ELISA for detection of β’-component (Onc k 5) protein, a major IgE-binding protein in salmon roe
    Ahmed A. Shalaby, Ryoga Maeda, Akihiko Ishida, Yutaka Shimizu, Hiroki Saeki, Masatoshi Maeki, Manabu Tokeshi
    Sensors and Actuators B: Chemical, 422, 01 Jan. 2025, [Peer-reviewed], [Invited], [Last author, Corresponding author]
    Scientific journal
  • Enhanced Broad-Spectrum Efficacy of an L2-Based mRNA Vaccine Targeting HPV Types 6, 11, 16, 18, with Cross-Protection Against Multiple Additional High-Risk Types
    Kosuke Tsukamoto, Akio Yamashita, Masatoshi Maeki, Manabu Tokeshi, Hirotatsu Imai, Akira Fukao, Toshinobu Fujiwara, Koji Okudera, Nobuhisa Mizuki, Kenji Okuda, Masaru Shimada
    Vaccines, Oct. 2024, [Peer-reviewed]
    Scientific journal
  • Investigation of the Nanoparticulation Method and Cell-Killing Effect following the Mitochondrial Delivery of Hydrophobic Porphyrin-Based Photosensitizers
    Rina Naganawa, Hanjun Zhao, Yuta Takano, Masatoshi Maeki, Manabu Tokeshi, Hideyoshi Harashima, Yuma Yamada
    International Journal of Molecular Sciences, 25, 8, 4294, 4294, MDPI AG, 12 Apr. 2024, [Peer-reviewed]
    English, Scientific journal, Photodynamic therapy is expected to be a less invasive treatment, and strategies for targeting mitochondria, the main sources of singlet oxygen, are attracting attention to increase the efficacy of photodynamic therapy and reduce its side effects. To date, we have succeeded in encapsulating the photosensitizer rTPA into MITO-Porter (MP), a mitochondria-targeted Drug Delivery System (DDS), aimed at mitochondrial delivery of the photosensitizer while maintaining its activity. In this study, we report the results of our studies to alleviate rTPA aggregation in an effort to improve drug efficacy and assess the usefulness of modifying the rTPA side chain to improve the mitochondrial retention of MITO-Porter, which exhibits high therapeutic efficacy. Conventional rTPA with anionic side chains and two rTPA analogs with side chains that were converted to neutral or cationic side chains were encapsulated into MITO-Porter. Low-MP (MITO-Porter with Low Drug/Lipid) exhibited high drug efficacy for all three types of rTPA, and in Low-MP, charged rTPA-encapsulated MP exhibited high drug efficacy. The cellular uptake and mitochondrial translocation capacities were similar for all particles, suggesting that differences in aggregation rates during the incorporation of rTPA into MITO-Porter resulted in differences in drug efficacy.
  • 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, 2, 6, 100363, 100363, Elsevier BV, Apr. 2024, [Peer-reviewed]
    English, Scientific journal
  • Development of Polymer-Lipid Hybrid Nanoparticles for Large-Sized Plasmid DNA Transfection.
    Masatoshi Maeki, Shuya Uno, Kaisei Sugiura, Yusuke Sato, Yoichiro Fujioka, Akihiko Ishida, Yusuke Ohba, Hideyoshi Harashima, Manabu Tokeshi
    ACS Applied Materials & Interfaces, 16, 2, 2110, 2119, 17 Jan. 2024, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, RNA and DNA delivery technologies using lipid nanoparticles (LNPs) have advanced significantly, as demonstrated by their successful application in mRNA vaccines. To date, commercially available RNA therapeutics include Onpattro, a 21 bp siRNA, and mRNA vaccines comprising 4300 nucleotides for COVID-19. However, a significant challenge remains in achieving efficient transfection, as the size of the delivered RNA and DNA increases. In contrast to RNA transfection, plasmid DNA (pDNA) transfection requires multiple steps, including cellular uptake, endosomal escape, nuclear translocation, transcription, and translation. The low transfection efficiency of large pDNA is a critical limitation in the development of artificial cells and their cellular functionalization. Here, we introduce polymer-lipid hybrid nanoparticles designed for efficient, large-sized pDNA transfection. We demonstrated that LNPs loaded with positively charged pDNA-polycation core nanoparticles exhibited a 4-fold increase in transfection efficiency for 15 kbp pDNA compared with conventional LNPs, which encapsulate a negatively charged pDNA-polycation core. Based on assessments of the size and internal structure of the polymer-lipid nanoparticles as well as hemolysis and cellular uptake analysis, we propose a strategy to enhance large-sized pDNA transfection using LNPs. This approach holds promise for accelerating the in vivo delivery of large-sized pDNA and advancing the development of artificial cells.
  • Sensitivity-improved blocking agent-free fluorescence polarization assay through surface modification using polyethylene glycol
    Hao Liu, Mao Fukuyama, Yu Ogura, Motohiro Kasuya, Sho Onose, Ayuko Imai, Koji Shigemura, Manabu Tokeshi, Akihide Hibara
    The Analyst, 149, 20, 5139, 5144, Royal Society of Chemistry (RSC), 2024, [Peer-reviewed]
    English, Scientific journal, A polyethylene glycol-based surface modification improved the sensitivity of fluorescence polarization assays in microfluidic devices, eliminating the need for blocking agents.
  • Understanding the effects of ethanol on the liposome bilayer structure using microfluidic-based time-resolved small-angle X-ray scattering and molecular dynamics simulations
    Masatoshi Maeki, Niko Kimura, Yuto Okada, Kazuki Shimizu, Kana Shibata, Yusuke Miyazaki, Akihiko Ishida, Kento Yonezawa, Nobutaka Shimizu, Wataru Shinoda, Manabu Tokeshi
    Nanoscale Advances, 6, 8, 2166, 2176, Royal Society of Chemistry (RSC), 2024, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal, We investigated ethanol-induced structural changes in liposomes on a time scale from microseconds to tens of seconds using a microfluidic-based small-angle X-ray scattering (SAXS) measurement system coupled with molecular dynamics (MD) simulations.
  • An Ionizable Lipid Material with a Vitamin E Scaffold as an mRNA Vaccine Platform for Efficient Cytotoxic T Cell Responses
    Ryotaro Oyama, Harumichi Ishigame, Hiroki Tanaka, Naho Tateshita, Moeko Itazawa, Ryosuke Imai, Naomasa Nishiumi, Jun-ichi Kishikawa, Takayuki Kato, Jessica Anindita, Yoshifumi Nishikawa, Masatoshi Maeki, Manabu Tokeshi, Kota Tange, Yuta Nakai, Yu Sakurai, Takaharu Okada, Hidetaka Akita
    ACS Nano, 17, 19, 18758, 18774, American Chemical Society (ACS), 26 Sep. 2023
    English, Scientific journal
  • A portable liquid chromatography system based on a separation/detection chip module consisting of a replaceable ultraviolet-visible absorbance or contactless conductivity detection unit
    Akihiko Ishida, Takuma Nishimura, Kaito Koyama, Masatoshi Maeki, Hirofumi Tani, Manabu Tokeshi
    Journal of Chromatography A, 1706, 464272, 464272, Elsevier BV, Sep. 2023, [Peer-reviewed], [Last author]
    Scientific journal
  • Rapid determination of domoic acid in seafood by fluorescence polarization immunoassay using a portable analyzer
    Yu Ogura, Mao Fukuyama, Motohiro Kasuya, Koji Shigemura, Sergei A. Eremin, Manabu Tokeshi, Akihide Hibara
    Analytical Sciences, 149, 20, 5139, 5144, Springer Science and Business Media LLC, 31 Aug. 2023, [Peer-reviewed]
    Scientific journal, Abstract

    Monitoring phycotoxin accumulation in marine products such as edible shellfish is a regulatory requirement in many countries. Therefore, a simple and rapid onsite quantification method is sought. Herein, we present a fluorescence polarization immunoassay (FPIA), a well-known one-step immunoassay, using a portable fluorescence polarization analyzer for domoic acid (DA), widely referred to as the primary toxin of amnesic shellfish poisoning (ASP). To establish FPIA for DA, the matrix effect of methanol, which is widely used to extract DA from shellfish, on FPIA was investigated. To validate this method, we performed a spike recovery test using oysters containing DA at a concentration equivalent to the regulatory limits of North America and the European Union (20 mg/kg). The recovery rate was found to be 79.4–114.7%, which is equivalent to that of the commercially available enzyme-linked immunosorbent assay (ELISA). We expect that this FPIA system will enable the quantitative onsite analysis of DA and significantly contribute to the safety of marine products.

    Graphical Abstract
  • Micro- and nanochamber array system for single enzyme assays.
    Kazuki Iijima, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Scientific reports, 13, 1, 13322, 13322, 16 Aug. 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Arrays of small reaction containers, ranging from 624 femtoliters (10-15 L) to 270 attoliters (10-18 L), for capturing a single enzyme molecule and measuring the activity were developed along with a new reversible sealing system based on a pneumatic valve actuator made of polydimethylsiloxane (PDMS). The valve was actuated by PBS solution, effectively preventing evaporation of the solution from the micro- and nanochambers and allowing the assay to be performed over a long period of time. The hydrolysis rates of β-D-galactosidase (β-gal), kcat, were decreased according to the decrease of the chamber size, and the overall tendency seems to be symmetrically related to the specific surface area of the chambers even under the prevented condition of non-specific adsorption. The spatial localization of the protons in the chambers, which might could affect the dissociation state of the proteins, was also investigated to explain the decrease in the hydrolysis rate. The developed chamber system developed here may be useful for artificially reproducing the confined intracellular environment and molecular crowding conditions.
  • Structure of lasso peptide epimerase MslH reveals metal-dependent acid/base catalytic mechanism
    Yu Nakashima, Atsushi Kawakami, Yasushi Ogasawara, Masatoshi Maeki, Manabu Tokeshi, Tohru Dairi, Hiroyuki Morita
    Nature Communications, 14, 1, Springer Science and Business Media LLC, 08 Aug. 2023, [Peer-reviewed]
    English, Scientific journal, Abstract

    The lasso peptide MS-271 is a ribosomally synthesized and post-translationally modified peptide (RiPP) consisting of 21 amino acids with D-tryptophan at the C-terminus, and is derived from the precursor peptide MslA. MslH, encoded in the MS-271 biosynthetic gene cluster (msl), catalyzes the epimerization at the Cα center of the MslA C-terminal Trp21, leading to epi-MslA. The detailed catalytic process, including the catalytic site and cofactors, has remained enigmatic. Herein, based on X-ray crystallographic studies in association with MslA core peptide analogues, we show that MslH is a metallo-dependent peptide epimerase with a calcineurin-like fold. The crystal structure analysis, followed by site-directed mutagenesis, docking simulation, and ICP-MS studies demonstrate that MslH employs acid/base chemistry to facilitate the reversible epimerization of the C-terminal Trp21 of MslA, by utilizing two pairs of His/Asp catalytic residues that are electrostatically tethered to a six-coordination motif with a Ca(II) ion via water molecules.
  • Construction of the systemic anticancer immune environment in tumour-bearing humanized mouse by using liposome-encapsulated anti-programmed death ligand 1 antibody-conjugated progesterone
    Yoshie Kametani, Ryoji Ito, Shino Ohshima, Yoshiyuki Manabe, Yusuke Ohno, Tomoka Shimizu, Soga Yamada, Nagi Katano, Daiki Kirigaya, Keita Ito, Takuya Matsumoto, Banri Tsuda, Hirofumi Kashiwagi, Yumiko Goto, Atsushi Yasuda, Masatoshi Maeki, Manabu Tokeshi, Toshiro Seki, Koichi Fukase, Mikio Mikami, Kiyoshi Ando, Hitoshi Ishimoto, Takashi Shiina
    Frontiers in Immunology, 14, 1173728, Frontiers Media SA, 10 Jul. 2023, [Peer-reviewed]
    English, Scientific journal
  • Antigen/Adjuvant-Displaying Enveloped Viral Replica as a Self-Adjuvanting Anti-Breast-Cancer Vaccine Candidate
    Keita Ito, Hiroto Furukawa, Hiroshi Inaba, Shino Ohshima, Yoshie Kametani, Masatoshi Maeki, Manabu Tokeshi, Xuhao Huang, Kazuya Kabayama, Yoshiyuki Manabe, Koichi Fukase, Kazunori Matsuura
    Journal of the American Chemical Society, 145, 29, 15838, 15847, American Chemical Society (ACS), 21 Jun. 2023, [Peer-reviewed]
    Scientific journal
  • A system that delivers an antioxidant to mitochondria for the treatment of drug-induced liver injury.
    Mitsue Hibino, Masatoshi Maeki, Manabu Tokeshi, Yoichi Ishitsuka, Hideyoshi Harashima, Yuma Yamada
    Scientific Reports, 13, 1, 6961, 6961, 10 May 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Mitochondria, a major source of reactive oxygen species (ROS), are intimately involved in the response to oxidative stress in the body. The production of excessive ROS affects the balance between oxidative responses and antioxidant defense mechanisms thus perturbing mitochondrial function eventually leading to tissue injury. Therefore, antioxidant therapies that target mitochondria can be used to treat such diseases and improve general health. This study reports on an attempt to establish a system for delivering an antioxidant molecule coenzyme Q10 (CoQ10) to mitochondria and the validation of its therapeutic efficacy in a model of acetaminophen (APAP) liver injury caused by oxidative stress in mitochondria. A CoQ10-MITO-Porter, a mitochondrial targeting lipid nanoparticle (LNP) containing encapsulated CoQ10, was prepared using a microfluidic device. It was essential to include polyethylene glycol (PEG) in the lipid composition of this LNP to ensure stability of the CoQ10, since it is relatively insoluble in water. Based on transmission electron microscope (TEM) observations and small angle X-ray scattering (SAXS) measurements, the CoQ10-MITO-Porter was estimated to be a 50 nm spherical particle without a regular layer structure. The use of the CoQ10-MITO-Porter improved liver function and reduced tissue injury, suggesting that it exerted a therapeutic effect on APAP liver injury.
  • Mass production system for RNA-loaded lipid nanoparticles using piling up microfluidic devices
    Masatoshi Maeki, Yuto Okada, Shuya Uno, Kaisei Sugiura, Yuichi Suzuki, Kento Okuda, Yusuke Sato, Masao Ando, Hiroyuki Yamazaki, Masaki Takeuchi, Akihiko Ishida, Hirofumi Tani, Hideyoshi Harashima, Manabu Tokeshi
    Applied Materials Today, 31, 101754, 101754, Elsevier BV, Apr. 2023, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Microfluidic paper-based analytical devices for cancer diagnosis
    Ahmed A. Shalaby, Chia Wen Tsao, Akihiko Ishida, Masatoshi Maeki, Manabu Tokeshi
    Sensors and Actuators B: Chemical, 379, 133243, 133243, Elsevier BV, 15 Mar. 2023, [Peer-reviewed], [Invited], [Last author, Corresponding author]
    English, Scientific journal, 45205131
  • Effects of Addition of Blocking Agents on Fluorescence Polarization Immunoassay of Okadaic Acid Using a Microfluidic Device
    Shunsuke CHIDA, Kazuki TAKAHASHI, Mao FUKUYAMA, Motohiro KASUYA, Masatoshi MAEKI, Akihiko ISHIDA, Hirofumi TANI, Koji SHIGEMURA, Anatoly V. ZHERDEV, Sergei A. EREMIN, Akihide HIBARA, Manabu TOKESHI
    BUNSEKI KAGAKU, 72, 3, 133, 138, Japan Society for Analytical Chemistry, 05 Mar. 2023, [Peer-reviewed], [Last author, Corresponding author]
    Japanese, Scientific journal
  • Development of an absorbance detection module using a deep UV light-emitting diode for a portable miniaturized liquid chromatograph
    Kaito Koyama, Takuma Nishimura, Akihiko Ishida, Mitsue Hibino, Masatoshi Maeki, Hirofumi Tani, Manabu Tokeshi
    BUNSEKI KAGAKU, 72, 3, 125, 131, Mar. 2023, [Peer-reviewed], [Last author]
    Japanese, Scientific journal
  • Controlling lamellarity and physicochemical properties of liposomes prepared using a microfluidic device
    Yuka Matsuura-Sawada, Masatoshi Maeki, Shuya Uno, Koichi Wada, Manabu Tokeshi
    Biomaterials Science, 11, 7, 2419, 2426, Royal Society of Chemistry (RSC), 2023, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Microfluidic Platform Enabling Efficient On-Device Preparation of Lipid Nanoparticles for Formulation Screening
    Yuka Matsuura-Sawada, Shuya Uno, Masatoshi Maeki, Koichi Wada, Manabu Tokeshi
    ACS Applied Engineering Materials, 1, 1, 278, 286, American Chemical Society (ACS), 10 Nov. 2022, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Effect of Organic Solvents on a Production of PLGA-Based Drug-Loaded Nanoparticles Using a Microfluidic Device
    Yi Bao, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    ACS Omega, 7, 37, 33079, 33086, 20 Sep. 2022, [Peer-reviewed], [Last author, Corresponding author]
    Scientific journal
  • Fine-tuning the encapsulation of a photosensitizer in nanoparticles reveals the relationship between internal structure and phototherapeutic effects.
    Fumika Kubota, Satrialdi, Yuta Takano, Masatoshi Maeki, Manabu Tokeshi, Hideyoshi Harashima, Yuma Yamada
    Journal of Biophotonics, 16, 3, e202200119, 01 Sep. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Photodynamic therapy (PDT) is a cancer therapy that uses a photosensitizer (PS) in the presence of oxygen molecules. Since singlet oxygen is highly reactive, it is important to deliver it to the target site. Thus, an efficient drug delivery system (DDS) is essential for enhancing the efficacy of such a treatment and protecting against the side effects of PDT. Here, we report on attempts to increase the therapeutic effect of PDT by using a DDS, a lipid nanoparticle (LNP). We prepared a porphyrin analog, rTPA (PS) that was encapsulated in LNPs using a microfluidic device. The findings indicated that the internal structure of the prepared particles changed depending on the amount of rTPA in LNPs. The photoactivity and cell-killing effect of PS in LNPs also changed when the amount of the cargo increased. These results suggest that the internal structure of LNPs is important factors that affect drug efficacy. This article is protected by copyright. All rights reserved.
  • Preparation of size-tunable sub-200 nm PLGA-based nanoparticles with a wide size range using a microfluidic platform
    Yi Bao, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    PLOS ONE, 17, 8, Aug. 2022, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • On the size-regulation of RNA-loaded lipid nanoparticles synthesized by microfluidic device.
    Kento Okuda, Yusuke Sato, Kazuki Iwakawa, Kosuke Sasaki, Nana Okabe, Masatoshi Maeki, Manabu Tokeshi, Hideyoshi Harashima
    Journal of Controlled Release, 348, 648, 659, 18 Jun. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, The use of lipid nanoparticles (LNPs) for nucleic acid delivery is now becoming a promising strategy with a number of clinical trials as vaccines or as novel therapies against a variety of genetic and infectious diseases. The use of microfluidics for the synthesis of the LNPs has attracted interest because of its considerable advantages over other conventional synthetic methods including scalability, reproducibility, and speed. However, despite the potential usefulness of large particles for nucleic acid delivery to dendritic cells (DCs) as a vaccine, the particle size of the LNPs prepared using microfluidics is typically limited to approximately from 30 to 100 nm. In this study, focusing on Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the effect of some synthetic parameters, including total flow rate, flow rate ratio, buffer pH, lipid concentration, molar ratio of PEG-lipid as well as salt concentration, on particle size was systematically examined by means of the design of experiment approaches. The findings indicated that the simple addition of salt (e.g. NaCl) to a buffer containing nucleic acids contributed greatly to the synthesis of large LNPs over 200 nm and this effect was concentration-dependent with respect to the salt. The effect of salt on particle size was consistent with a Hofmeister series. The systemic injection of larger mRNA-loaded LNPs resulted in a higher transgene expression in mouse splenic DCs, a higher activation of various splenic immune cells, and had a superior effect as a therapeutic cancer vaccine in a syngeneic mouse model compared to the smaller-sized counterpart with constant lipid composition prepared with lower NaCl concentration. Collectively, size-regulation by the simple addition of salt is a promising strategy for developing potent LNPs.
  • Non-competitive fluorescence polarization immunosensing for CD9 detection using a peptide as a tracer.
    Kazuki Takahashi, Shunsuke Chida, Thanawat Suwatthanarak, Mikiko Iida, Min Zhang, Mao Fukuyama, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Takao Yasui, Yoshinobu Baba, Akihide Hibara, Mina Okochi, Manabu Tokeshi
    Lab on a Chip, 22, 16, 2971, 2977, 17 Jun. 2022, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, This paper is the first report of a non-competitive fluorescence polarization immunoassay (NC-FPIA) using a peptide as a tracer. The NC-FPIA can easily and quickly quantify the target after simply mixing them together. This feature is desirable for point-of-need applications such as clinical diagnostics, infectious disease screening, on-site analysis for food safety, etc. In this study, the NC-FPIA was applied to detect CD9, which is one of the exosome markers. We succeeded in detecting not only CD9 but also CD9 expressing exosomes derived from HeLa cells. This method can be applied to various targets if a tracer for the target can be prepared, and expectations are high for its future uses.
  • Microfluidic technologies and devices for lipid nanoparticle-based RNA delivery
    Masatoshi Maeki, Shuya Uno, Ayuka Niwa, Yuto Okada, Manabu Tokeshi
    Journal of Controlled Release, 344, 80, 96, Elsevier BV, Apr. 2022, [Peer-reviewed], [Invited], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal
  • Enzyme kinetics in confined geometries at the single enzyme level.
    Hisashi Murahara, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    The Analyst, 147, 7, 1375, 1384, 28 Mar. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, The effects of increased confinement on the catalytic rates of individual enzyme molecules were studied at the single molecule level using femtolitre chambers and molecular crowders. According to the increase of confinement, from micro to nanometer cubic space in the chambers, the hydrolysis rate of β-galactosidase (β-gal) decreased to one-tenth of the rate in bulk. When molecular crowders suppressed the diffusion rates that reduced the collision chance of an enzyme and a substrate, the hydrolysis rate also decreased, which happened also in the case of femtolitre chambers. However, their kinetic trend was different especially from the viewpoint of the diffusion rates in diffusion-limited space. These data suggested that cell or organelle-scale confined environments might affect the kinetics of biochemical reactions and emphasized the importance of understanding enzyme kinetics in the in vivo environment.
  • Production of siRNA-Loaded Lipid Nanoparticles using a Microfluidic Device.
    Masatoshi Maeki, Yuto Okada, Shuya Uno, Ayuka Niwa, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Journal of Visualized Experiments : JoVE, 2022, 181, 22 Mar. 2022, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal
  • Dimethoxytriadinylation LC-MS/MS of Novichok A-Series Degradation Products in Human Urine.
    Akinori Yamaguchi, Hajime Miyaguchi, Manabu Tokeshi
    Analytical Chemistry, 94, 11, 4658, 4665, 22 Mar. 2022, [Peer-reviewed], [Last author], [International Magazine]
    English, Scientific journal, Novichok A-series compounds, novel nerve agents, pose an increasing threat to citizens worldwide; however, no analytical methods have been reported for detecting their hydrolysis products. Herein, a screening method was developed to detect and identify Novichok A-series degradation products (hydrolysates of A230, A232, A234, A262, and one related compound) and alkyl methylphosphonic acids (RMPAs, conventional nerve agent hydrolysates) using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We identified a suitable derivatization reagent, 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM), and optimized the reaction conditions. The derivatized esters of Novichok A-series degradation products were stable and easily detected. We used this derivatization to achieve the first analytical method for Novichok hydrolysis products in urine (0.40-4.0 ng/mL). The detection limits of the RMPAs (0.1-0.4 ng/mL) were comparable to those presented in previous reports involving pentafluorobenzylation or direct LC-MS/MS. The applicability of the newly developed method was evaluated by analyzing urine samples from the OPCW Fifth Biomedical Proficiency Test.
  • Bioanalytical Technologies for Safety Control of Fish and Seafood by Sensitive Rapid Tests for Phycotoxins
    S A Eremin, A V Zherdev, M Tokeshi, A Hibara
    IOP Conference Series: Earth and Environmental Science, 988, 4, 042041, 042041, IOP Publishing, 01 Feb. 2022
    Scientific journal, Abstract

    Wide and operate safety monitoring of foodstuffs is highly demanded in modern society. This work aims to develop and characterize new test systems for control of phycotoxins, dangerous contaminants of fish and seafood. For rapid and productive testing, 2 methods have been implemented: immunochromatographic assay and fluorescence polarization immunoassay. Various approaches for reducing the limit of detection of target analytes have been considered, including changes in the use of optical and fluorescent labels and varied order of the detected complexes formation. Antibodies and aptamers have been considered as receptor molecules. The developed techniques provide rapid (20–30 minutes, including sample preparation) and sensitive testing. Their effectiveness has been shown for different kinds of fish and seafood. Portable detectors have been proposed that allow testing directly at the sampling points, without transportation to centralized laboratories.
  • Microfluidic Device-Enabled Mass Production of Lipid-Based Nanoparticles for Applications in Nanomedicine and Cosmetics
    Yuka Matsuura-Sawada, Masatoshi Maeki, Takaaki Nishioka, Ayuka Niwa, Jun Yamauchi, Masashi Mizoguchi, Koichi Wada, Manabu Tokeshi
    ACS Applied Nano Materials, 5, 6, 7867, 7876, 2022, [Peer-reviewed], [Last author, Corresponding author]
    Scientific journal
  • Determination of blood lithium-ion concentration using digital microfluidic whole-blood separation and preloaded paper sensors
    Takeshi Komatsu, Manabu Tokeshi, Shih-Kang Fan
    Biosensors and Bioelectronics, 195, 113631, 113631, Elsevier BV, Jan. 2022, [Peer-reviewed], [Corresponding author]
    English, Scientific journal
  • Topology-Dependent Interaction of Cyclic Poly(ethylene glycol) Complexed with Gold Nanoparticles against Bovine Serum Albumin for a Colorimetric Change
    Onyinyechukwu Justina Oziri, Masatoshi Maeki, Manabu Tokeshi, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Takuya Yamamoto
    Langmuir, 38, 17, 5286, 5295, American Chemical Society (ACS), 08 Dec. 2021, [Peer-reviewed]
    Scientific journal
  • Electrochemical enzyme-based blood ATP and lactate sensor for a rapid and straightforward evaluation of illness severity
    Keine Nishiyama, Ryohei Mizukami, Shizuka Kuki, Akihiko Ishida, Junji Chida, Hiroshi Kido, Masatoshi Maeki, Hirofumi Tani, Manabu Tokeshi
    Biosensors and Bioelectronics, 113832, 113832, Elsevier BV, Nov. 2021, [Peer-reviewed], [Last author, Corresponding author]
    Scientific journal
  • Microchip immunoassays for monitoring renal function: Rapid, low‐cost, and highly sensitive quantification of urinary biomarkers of diabetic nephropathy
    Toshihiro Kasama, Miaomiao Sun, Noritada Kaji, Shin’Ichi Akiyama, Yukio Yuzawa, Manabu Tokeshi, Seiichi Matsuo, Yoshinobu Baba
    Micromachines, 12, 11, Nov. 2021, [Peer-reviewed]
    Scientific journal
  • Determination of Deoxynivalenol in Wheat, Barley, Corn Meal, and Wheat-Based Products by Simultaneous Multisample Fluorescence Polarization Immunoassay Using a Portable Analyzer
    Ayano Nakamura, Mitsutoshi Aoyagi, Mao Fukuyama, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Koji Shigemura, Akihide Hibara, Manabu Tokeshi
    ACS Food Science & Technology, 1, 9, 1623, 1628, American Chemical Society (ACS), 15 Oct. 2021, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Facile and rapid detection of SARS-CoV-2 antibody based on a noncompetitive fluorescence polarization immunoassay in human serum samples
    Keine Nishiyama, Kazuki Takahashi, Mao Fukuyama, Motohiro Kasuya, Ayuko Imai, Takumi Usukura, Nako Maishi, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Kyoko Hida, Koji Shigemura, Akihide Hibara, Manabu Tokeshi
    Biosensors and Bioelectronics, 190, 113414, 113414, Elsevier BV, Oct. 2021, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Using a Paper-Based Analytical Device Designed for Remote Learning Environments to Achieve Simple Quantitative Colorimetry without Micropipettes
    Takeshi Komatsu, Ryan Russel Gabatino, Harrienica Hofileña, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Journal of Chemical Education, 98, 9, 3050, 3054, 14 Sep. 2021, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Paper-Based Analytical Device for the On-Site Detection of Nerve Agents
    Akinori Yamaguchi, Hajime Miyaguchi, Akihiko Ishida, Manabu Tokeshi
    ACS Applied Bio Materials, 4, 8, 6512, 6518, American Chemical Society (ACS), 16 Aug. 2021, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, We report a colorimetric paper-based microfluidic device based on an enzyme inhibition assay that allows the on-site detection of nerve agents by sampling and wicking. The sample and reagents are automatically transported through the channel where an enzyme inhibition reaction is conducted, followed by an enzyme-substrate reaction and a color reaction. This device can detect 0.1 μg/mL of the nerve agent VX in a 2.5 μL drop and is nerve agent selective and robust against temperature, pH, and several liquids. We confirmed that sampling procedures (dilution and wiping) are applicable to this device. Furthermore, the fabrication procedure is easy, and the cost is at most a few tens of cents. Thus, the present device provides a practical method for the urgent detection of nerve agents in suspected chemical terrorism incidents.
  • Delivery of Oligonucleotides Using a Self-Degradable Lipid-Like Material.
    Hiroki Tanaka, Nae Takata, Yu Sakurai, Tokuyuki Yoshida, Takao Inoue, Shinya Tamagawa, Yuta Nakai, Kota Tange, Hiroki Yoshioka, Masatoshi Maeki, Manabu Tokeshi, Hidetaka Akita
    Pharmaceutics, 13, 4, 13 Apr. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal, The world-first success of lipid nanoparticle (LNP)-based siRNA therapeutics (ONPATTRO®) promises to accelerate developments in siRNA therapeutics/gene therapy using LNP-type drug delivery systems (DDS). In this study, we explore the optimal composition of an LNP containing a self-degradable material (ssPalmO-Phe) for the delivery of oligonucleotides. siRNA or antisense oligonucleotides (ASO) were encapsulated in LNP with different lipid compositions. The hepatic knockdown efficiency of the target genes and liver toxicity were evaluated. The optimal compositions for the siRNA were different from those for ASO, and different from those for mRNA that were reported in a previous study. Extracellular stability, endosomal escape and cellular uptake appear to be the key processes for the successful delivery of mRNA, siRNA and ASO, respectively. Moreover, the compositions of the LNPs likely contribute to their toxicity. The lipid composition of the LNP needs to be optimized depending on the type of nucleic acids under consideration if the applications of LNPs are to be further expanded.
  • Simple Approach for Fluorescence Signal Amplification Utilizing a Poly(vinyl alcohol)-Based Polymer Structure in a Microchannel.
    Keine Nishiyama, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Hideaki Hisamoto, Manabu Tokeshi
    ACS Omega, 6, 12, 8340, 8345, 30 Mar. 2021, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, Analytical methods with fluorescence detection are in widespread use for detecting low abundance analytes. Here, we report a simple method for fluorescence signal amplification utilizing a structure of an azide-unit pendant water-soluble photopolymer (AWP) in a microchannel. The AWP is a poly(vinyl alcohol)-based photocross-linkable polymer, which is often used in biosensors. We determined that the wall-like structure of the AWP (AWP-wall) constructed in a microchannel functioned as an amplifier of a fluorescence signal. When a solution of fluorescent molecules was introduced into the microchannel having the AWP-wall, the fluorescent molecules accumulated inside the AWP-wall by diffusion. Consequently, the fluorescence intensity inside the AWP-wall increased locally. Among the fluorescent molecules considered in this paper, 9H-(1,3-dichloro-9,9-dimethylacridin-2-one-7-yl) (DDAO) showed the highest efficiency of fluorescence signal amplification. We prepared a calibration curve for DDAO using the fluorescence intensity inside the AWP-wall, and the sensitivity was 5-fold that for the microchannel without the AWP-wall. This method realizes the improved sensitivity of fluorescence detection easily because the fluorescence signal was amplified only by injecting the solution into the microchannel having the AWP-wall. Furthermore, since this method is not limited to only the use of microchannel, we expect it to be applicable in various fields.
  • Dip-Type Paper-Based Analytical Device for Straightforward Quantitative Detection without Precise Sample Introduction.
    Takeshi Komatsu, Ryoga Maeda, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    ACS sensors, 6, 3, 1094, 1102, 26 Mar. 2021, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, The development of low-cost, user-friendly paper-based analytical devices (PADs) that can easily measure target chemicals is attracting attention. However, most PADs require manipulation of the sample using sophisticated micropipettes for quantitative analyses, which restricts their user-friendliness. In addition, immobilization of detection molecules to cellulose fibers is essential for achieving good measuring ability as it ensures the homogeneity of color development. Here, we have described a dip-type PAD that does not require pipette manipulation for sample introduction and immobilization of detection molecules to cellulose fibers and its application to ascorbic acid (AA) and pH assays. The PAD consisted of a dipping area and two channels, each with two detection zones. The developed PADs show color distribution in the two detection zones depending on the sample flow from the dipping area. In comparison with a PAD that has one detection zone at the end of the channel, our developed device achieved higher sensitivity (limit of detection (LOD), 0.22 mg/mL) and reproducibility (maximum coefficient of variation (CV), 2.4%) in AA detection. However, in pH detection, the reproducibility of the PAD with one detection zone at the end of the channel (maximum CV, 21%) was worse than that with two zones (maximum CV, 11%). Furthermore, a dipping time over 3 s did not affect color formation or calibration curves in AA detection: LODs at 3 and 30 s dipping time were 18 and 5.8 μg/mL, respectively. The simultaneous determination of AA and pH in various beverages was performed with no significant difference compared to results of the conventional method.
  • Lipid nanoparticles loaded with ribonucleoprotein-oligonucleotide complexes synthesized using a microfluidic device exhibit robust genome editing and hepatitis B virus inhibition.
    Yuichi Suzuki, Haruno Onuma, Risa Sato, Yusuke Sato, Akari Hashiba, Masatoshi Maeki, Manabu Tokeshi, Mohammad Enamul Hoque Kayesh, Michinori Kohara, Kyoko Tsukiyama-Kohara, Hideyoshi Harashima
    Journal of Controlled Release, 330, 61, 71, 10 Feb. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal, The clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) system has considerable therapeutic potential for use in treating a wide range of intractable genetic and infectious diseases including hepatitis B virus (HBV) infections. While non-viral delivery technologies for the CRISPR/Cas system are expected to have clinical applications, difficulties associated with the clinically relevant synthesis of formulations and the poor efficiency of delivery severely hinder therapeutic genome editing. We report herein on the production of a lipid nanoparticle (LNP)-based CRISPR/Cas ribonucleoprotein (RNP) delivery nanoplatform synthesized using a clinically relevant mixer-equipped microfluidic device. DNA cleavage activity and the aggregation of Cas enzymes was completely avoided under the optimized synthetic conditions. The optimized formulation, which was identified through 2 steps of design of experiments, exhibited excellent gene disruption (up to 97%) and base substitution (up to 23%) without any apparent cytotoxicity. The addition of negative charges to the RNPs by complexing single-stranded oligonucleotide (ssON) significantly enhanced the delivery of both Cas9 and Cpf1 RNPs. The optimized formulation significantly suppressed both HBV DNA and covalently closed circular DNA (cccDNA) in HBV-infected human liver cells compared to adeno-associated virus type 2 (AAV2). These findings represent a significant contribution to the development of CRISPR/Cas RNP delivery technology and its practical applications in genome editing therapy.
  • Non-competitive fluorescence polarization immunoassay for detection of H5 avian influenza virus using a portable analyzer.
    Keine Nishiyama, Yohei Takeda, Kazuki Takahashi, Mao Fukuyama, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Koji Shigemura, Akihide Hibara, Haruko Ogawa, Manabu Tokeshi
    Analytical and Bioanalytical Chemistry, 413, 18, 4619, 4623, 05 Feb. 2021, [Peer-reviewed], [Invited], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, Nowadays, the diagnosis of viral infections is receiving broad attention. We have developed a non-competitive fluorescence polarization immunoassay (NC-FPIA), which is a separation-free immunoassay, for a virus detection. H5 subtype avian influenza virus (H5-AIV) was used as a model virus for the proof of concept. The fluorescein-labeled Fab fragment that binds to H5 hemagglutinin was used for NC-FPIA. The purified H5-AIV which has H5 hemagglutinin was mixed with the fluorescein-labeled Fab fragment. After that, the degree of fluorescence polarization was measured with a portable FPIA analyzer. H5-AIV was successfully detected with an incubation time of 15 min. In addition, the portable FPIA analyzer enables performance of on-site NC-FPIA with a sample volume of 20 μL or less. This is the first research of detecting a virus particle by FPIA. This NC-FPIA can be applied to rapid on-site diagnosis of various viruses.
  • One-Step Production Using a Microfluidic Device of Highly Biocompatible Size-Controlled Noncationic Exosome-like Nanoparticles for RNA Delivery
    Niko Kimura, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    ACS Applied Bio Materials, 4, 2, 1783, 1793, Feb. 2021, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Rapid, sensitive universal paper-based device enhances competitive immunoassays of small molecules.
    Takeshi Komatsu, Yuki Sato, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Analytica Chimica Acta, 1144, 85, 95, 01 Feb. 2021, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, Competitive immunoassays comprise the standard means of detecting small molecules. However, conventional methods using microwells are difficult to apply during point-of-care tests (POCT) because they require complicated handling and are time consuming. Although paper-based analytical devices (PAD) have received considerable focus because of their rapid and straightforward operation, only a few devices have been proposed for competitive immunoassays. Herein, we describe a novel universal PAD format with a 3-dimensional configuration for competitive immunoassays that rapidly and sensitively detects small molecules. The proposed device comprised a layered structure with uniform color formation and high capture efficiency between antigen and antibody that results in rapid and reproducible results. The device rapidly (90 s) assayed biotin as a model target, with a limit of detection (LOD) of 5.08 ng mL-1, and detected progesterone with an LOD of 84 pg mL-1 within 5 min. Moreover, sample volumes and reagent consumption rates were minimized. Thus, our device could be applied to competitive immunoassays of various small molecules in POCT.
  • PEGylation of Silver Nanoparticles by Physisorption of Cyclic Poly(Ethylene Glycol) for Enhanced Dispersion Stability, Antimicrobial Activity, and Cytotoxicity
    Onyinyechukwu Oziri, Yubo Wang, Tomohisa Watanabe, Shuya Uno, Masatoshi Maeki, Manabu Tokeshi, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Yutaka Miura, Takuya Yamamoto
    Nanoscale Advances, 4, 2, 532, 545, Royal Society of Chemistry (RSC), 2021, [Peer-reviewed]
    Scientific journal, Silver nanoparticles (AgNPs) are practically valuable in biological applications. However, no steady PEGylation has been established, which is essential for internal use in humans or animals. In this study, cyclic...
  • Three-dimensional, symmetrically assembled microfluidic device for lipid nanoparticle production
    Niko Kimura, Masatoshi Maeki, Kosuke Sasaki, Yusuke Sato, Akihiko Ishida, Hirofumi Tani, Hideyoshi Harashima, Manabu Tokeshi
    RSC Advances, 11, 3, 1430, 1439, Jan. 2021, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Enhanced dispersion stability of gold nanoparticles by the physisorption of cyclic poly(ethylene glycol).
    Yubo Wang, Jose Enrico Q Quinsaat, Tomoko Ono, Masatoshi Maeki, Manabu Tokeshi, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-Ichiro Sato, Yutaka Miura, Takuya Yamamoto
    Nature communications, 11, 1, 6089, 6089, 30 Nov. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Nano-sized metal particles are attracting much interest in industrial and biomedical applications due to the recent progress and development of nanotechnology, and the surface-modifications by appropriate polymers are key techniques to stably express their characteristics. Herein, we applied cyclic poly(ethylene glycol) (c-PEG), having no chemical inhomogeneity, to provide a polymer topology-dependent stabilization for the surface-modification of gold nanoparticles (AuNPs) through physisorption. By simply mixing c-PEG, but not linear counterparts, enables AuNPs to maintain dispersibility through freezing, lyophilization, or heating. Surprisingly, c-PEG endowed AuNPs with even better dispersion stability than thiolated PEG (HS-PEG-OMe). The stronger affinity of c-PEG was confirmed by DLS, ζ-potential, and FT-IR. Furthermore, the c-PEG system exhibited prolonged blood circulation and enhanced tumor accumulation in mice. Our data suggests that c-PEG induces physisorption on AuNPs, supplying sufficient stability toward bio-medical applications, and would be an alternative approach to the gold-sulfur chemisorption.
  • The use of design of experiments with multiple responses to determine optimal formulations for in vivo hepatic mRNA delivery.
    Akari Hashiba, Manaya Toyooka, Yusuke Sato, Masatoshi Maeki, Manabu Tokeshi, Hideyoshi Harashima
    Journal of controlled release, 327, 467, 476, 10 Nov. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Although great advances have been made in the delivery of short RNAs by lipid nanoparticles (LNPs), the optimal formulation composition and physicochemical properties of LNPs for long RNA (including mRNA) remain unclear. In the present study, we optimized the lipid composition of liver-targeted mRNA-loaded LNPs that were prepared with pH-sensitive cationic lipids that had been previously designed for siRNA delivery through a two stepped design of experiment (DoE). Multiple responses including physicochemical properties, gene expression, and liver-specificity were analyzed in order, not only to understand the role of each formulation parameter, but also to examine parameters that would be difficult to predict. We found that particle size and the PEG-to-phospholipid (PEG/PL) ratio were additional key factors for liver-specific gene expression in addition to the other formulation factors. The optimized formulation showed a better gene expression compared to other lipid formulations from industry leaders. These findings suggest that a "DoE with multiple responses" approach can be used to predict significant parameters and permit optimized formulations to be prepared more efficiently.
  • Noncompetitive Fluorescence Polarization Immunoassay for Protein Determination.
    Mao Fukuyama, Ayano Nakamura, Keine Nishiyama, Ayuko Imai, Manabu Tokeshi, Koji Shigemura, Akihide Hibara
    Analytical Chemistry, 92, 21, 14393, 14397, 03 Nov. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Fluorescent polarization immunoassay (FPIA) is a single-step immunoassay method that is applicable to point-of-care testing; however, its applicability to large biomolecules has been restricted because ordinary FPIA is a competitive assay. Here, we report a noncompetitive FPIA using the variable domain from the heavy chain of a camelid antibody (VHH antibody). FPIA with VHH was successfully used to quantitate rabbit immunoglobulin G (IgG) and demonstrated a wider response range than that observed with antibody-binding (Fab) fragment. Then, using a portable FPIA instrument, a VHH-based immunoassay of human IgG in a human serum certified reference material was demonstrated.
  • Silica Nanopillar Arrays for Monitoring Diffraction-Based Label-Free Biomolecule Separation
    Taiga Ajiri, Takao Yasui, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Junji Nishii, Yoshinobu Baba, Manabu Tokeshi
    ACS Applied Nano Materials, 3, 9, 8810, 8816, Sep. 2020, [Last author, Corresponding author]
    English, Scientific journal
  • Room-temperature crystallography using a microfluidic protein crystal array device and its application to protein-ligand complex structure analysis
    Masatoshi Maeki, Sho Ito, Reo Takeda, Go Ueno, Akihiko Ishida, Hirofumi Tani, Masaki Yamamoto, Manabu Tokeshi
    Chemical Science, 11, 34, 9072, 9087, Sep. 2020, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • One-step non-competitive fluorescence polarization immunoassay based on a Fab fragment for C-reactive protein quantification
    Keine Nishiyama, Mao Fukuyama, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Akihide Hibara, Manabu Tokeshi
    Sensors and Actuators B: Chemical, 128982, 128982, Elsevier BV, Sep. 2020, [Peer-reviewed], [Last author, Corresponding author]
    Scientific journal
  • Rapid detection of anti-H5 avian influenza virus antibody by fluorescence polarization immunoassay using a portable fluorescence polarization analyzer.
    Keine Nishiyama, Yohei Takeda, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Koji Shigemura, Akihide Hibara, Yutaka Yonezawa, Kunitoshi Imai, Haruko Ogawa, Manabu Tokeshi
    Sensors and Actuators. B, Chemical, 316, 128160, 128160, 01 Aug. 2020, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, A rapid, facile and selective detection of anti-H5 subtype avian influenza virus (AIV) antibody in serum by fluorescence polarization immunoassay (FPIA) was achieved. A fragment of recombinant H5 subtype AIV hemagglutinin was produced and labeled with fluorescein to use it as a labeled antigen in FPIA. This labeled antigen was mixed with anti-AIV sera (H1-H16 subtypes) and FP of the mixture was measured using a portable FP analyzer on a microdevice. It was found that FP increased in proportion to the concentration of anti-H5 AIV antibody (serum) and was significantly higher than FP obtained with the other sera. The selective detection of anti-H5 subtype AIV antibody was confirmed. The required volume of original sample was 2 μL and analysis time was within 20 min. This detection system realizes an efficient on-site diagnosis and surveillance of AIV.
  • Development of a Microfluidic-Based Post-Treatment Process for Size-Controlled Lipid Nanoparticles and Application to siRNA Delivery.
    Niko Kimura, Masatoshi Maeki, Yusuke Sato, Akihiko Ishida, Hirofumi Tani, Hideyoshi Harashima, Manabu Tokeshi
    ACS Applied Materials & Interfaces, 12, 30, 34011, 34020, 29 Jul. 2020, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, Microfluidic methodologies for preparation of lipid nanoparticles (LNPs) based on an organic solvent injection method enable precise size control of the LNPs. After preparation of LNPs, the organic solvent injection method needs some post-treatments, such as overnight dialysis or direct dilution with a buffer solution. LNP production using the microfluidic-based organic solvent injection method is dominated by kinetics rather than thermodynamics. Kinetics of ethanol removal from the inner and outer membranes of LNPs could induce a structural change in the membrane that could lead to fusion of LNPs. However, the effects of microfluidic post-treatment on the final size of LNPs have not been sufficiently understood. Herein, we investigated the effect of the post-treatment processes on the final product size of LNPs in detail. A simple baffle device and a model lipid system composed of a neutral phospholipid (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, POPC) and cholesterol were used to produce the LNPs. We demonstrated that flow conditions of the post-treatment diluting the remaining ethanol in the LNP suspension affected the final product size of LNPs. Based on the findings, we developed an integrated baffle device composed of an LNP production region and a post-treatment region for a microfluidic-based LNP production system; this integrated baffle device prevented the undesirable aggregation or fusion of POPC LNPs even for the high-lipid-concentration condition. Finally, we applied our concept to small interfering RNA (siRNA) delivery and confirmed that no significant effects due to the continuous process occurred on the siRNA encapsulation efficiency, biological distribution, and knockdown activity. The microfluidic post-treatment method is expected to contribute to the production of LNPs for practical applications and the development of novel LNP-based nanomedicines.
  • Real-Time Measurement of Protein Crystal Growth Rates within the Microfluidic Device to Understand the Microspace Effect.
    Masatoshi Maeki, Shohei Yamazaki, Reo Takeda, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    ACS Omega, 5, 28, 17199, 17206, 21 Jul. 2020, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, Preparation of high-quality protein crystals is a major challenge in protein crystallography. Natural convection is considered to be an uncontrollable factor of the crystallization process at the ground level as it disturbs the concentration gradient around the growing crystal, resulting in lower-quality crystals. A microfluidic environment expects an imitated microgravity environment because of the small Gr number. However, the mechanism of protein crystal growth in the microfluidic device was not elucidated due to limitations in measuring the crystal growth process within the device. Here, we demonstrate the real-time measurement of protein crystal growth rates within the microfluidic devices by laser confocal microscopy with differential interference contrast microscopy (LCM-DIM) at the nanometer scale. We confirmed the normal growth rates in the 20 and 30 μm-deep microfluidic device to be 42.2 and 536 nm/min, respectively. In addition, the growth rate of crystals in the 20 μm-deep microfluidic device was almost the same as that reported in microgravity conditions. This phenomenon may enable the development of more accessible alternatives to the microgravity environment of the International Space Station.
  • Observation of Ethanol-Induced Condensation and Decondensation Processes at a Single-DNA Molecular Level in Microfluidic Devices Equipped with a Rapid Solution Exchange System.
    Hiroshi Suzuki, Kentaro Fujiyoshi, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Chemistry, 92, 13, 9132, 9137, 07 Jul. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Conformational transitions from secondary (e.g., B- to A-form DNA) to higher-order (e.g., coil to globule) transitions play important roles in genome expression and maintenance. Several single-molecule approaches using microfluidic devices have been used to determine the kinetics of DNA chromatin assembly because microfluidic devices can afford stretched DNA molecules through laminar flow and rapid solution exchange. However, some issues, particularly the uncertainty of time 0 in the solution exchange process, are encountered. In such kinetic experiments, it is critical to determine when the target solution front approaches the target DNA molecules. Therefore, a new design for a microfluidic device is developed that enables the instantaneous exchange of solutions in the observation channel, allowing accurate measurements of DNA conformational transitions; stepwise, ethanol-induced conformational transitions are revealed. Although full DNA contraction from coil to globule is observed with >50% ethanol, no outstanding change is observed at concentrations <40% in 10 min. With 50% ethanol solution, the DNA conformational transition passes through two steps: (i) fast and constant-velocity contraction and (ii) relatively slow contraction from the free end. The first process is attributed to the B to A conformational transition by gradual dehydration. The second process is due to the coil-globule transition as the free end of DNA starts the contraction. This globular structure formation counteracts the shear force from the microfluids and decelerates the contraction velocity. This real-time observation system can be applied to the kinetic analysis of DNA conformational transitions such as kinetics of chromatin assembly and gene expression.
  • Paper-Based Device for the Facile Colorimetric Determination of Lithium Ions in Human Whole Blood.
    Takeshi Komatsu, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    ACS Sensors, 5, 5, 1287, 1294, 22 May 2020, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, Lithium carbonate is an effective medicine for the treatment of the bipolar disorder, but the concentration of lithium in the patient's blood must be frequently monitored because of its toxicity. To date, no colorimetric methods of lithium ion detection in whole blood without pretreatment have been reported. Here, we report a colorimetric paper-based device that allows point-of-care testing in one step. This device is composed of two paper-based elements linked to each other: a blood cell separation unit and a colorimetric detection unit. After a portion of whole blood has been placed on the end of the separation unit, plasma in the sample is automatically transported to the detection unit, which displays a diagnostic color. The key feature of this device is its simple, user-friendly operation. The limit of detection is 0.054 mM and the coefficient of variance is below 6.1%, which are comparable to those of conventional instruments using the same colorimetric reaction. Furthermore, we achieved high recovery (>90%) and reproducibility (<9.8%) with spiked human blood samples. Thus, the presented device provides an alternative method for the regular monitoring of lithium concentrations in the treatment of bipolar disorder by augmenting the coefficient of variation (maximum value, 6.1%).
  • The Effect of Size and Charge of Lipid Nanoparticles Prepared by Microfluidic Mixing on Their Lymph Node Transitivity and Distribution.
    Takashi Nakamura, Minori Kawai, Yusuke Sato, Masatoshi Maeki, Manabu Tokeshi, Hideyoshi Harashima
    Molecular Pharmaceutics, 17, 3, 944, 953, 02 Mar. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Because the lymph node (LN) is a critical organ for inducing immune responses against pathogens and cancers, the transport of immune functional molecules such as antigens and adjuvants to LNs by delivery systems is a useful strategy for the effective outcome of an immune response. The size and charge of a delivery system largely affect the transitivity to and distribution within LN. Although pH-sensitive lipid nanoparticles (LNPs) prepared by microfluidic mixing are the latest delivery system to be applied clinically, the effects of their size and charge on the transitivity to and distribution within LN are currently unknown. We investigated the size and charge effect of LNPs prepared by microfluidic mixing on transitivity to and distribution within LNs. A 30 nm-sized LNP (30-LNP) was efficiently translocated to LNs and was taken up by CD8+ dendritic cells, while the efficiency was drastically decreased in the cases of 100 and 200 nm-sized LNPs. Furthermore, a comparative study between neutral, positively, and negatively charged 30-LNP revealed that the negative 30-LNP moved to the LN more efficiently than the other LNPs. Interestingly, the negative 30-LNP reached the deep cortex, namely, the T cell zone. Our findings provide informative insights for designing LN-targeting LNPs prepared by microfluidic mixing and for the translocation of nanoparticles in LNs.
  • Hydrophobic scaffolds of pH-sensitive cationic lipids contribute to miscibility with phospholipids and improve the efficiency of delivering short interfering RNA by small-sized lipid nanoparticles.
    Yusuke Sato, Nana Okabe, Yusuke Note, Kazuki Hashiba, Masatoshi Maeki, Manabu Tokeshi, Hideyoshi Harashima
    Acta Biomaterialia, 102, 341, 350, 15 Jan. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Despite the fact that small-sized lipid nanoparticles (LNPs) are important for improved tissue penetration and efficient drug delivery, their poor stability and intracellular trafficking significantly hinders their use as potent small-sized LNPs. It has been reported that both the diffusion of lipid components from LNPs and the adsorption of proteins on the surface of LNPs are responsible for their decreased potency. To overcome this issue, we focused on the chemical structure of hydrophobic scaffolds of pH-sensitive cationic lipids with various lengths and shapes. LNPs composed of a pH-sensitive cationic lipid with long, linear scaffolds induced gene silencing in a dose-dependent manner, while LNPs with a classical scaffold length (C18) failed. Replacing the helper lipid from cholesterol to egg sphingomyelin (ESM) resulted in the formation of smaller LNPs with a diameter of ~22 nm and enhanced gene silencing activity. Most of the ESMs were located in the outer layer and functioned to stabilize the LNPs. Long, linear scaffolds contributed to immiscibility with phosphocholine-containing lipids including ESM. This contribution was dependent on the scaffold length of pH-sensitive cationic lipids. Although phosphocholine-containing lipids usually inhibit membrane fusion-mediated endosomal escape, long, linear scaffolds contributed to avoiding the inhibitory effect and to enhance the potency of the LNPs. These findings provide useful information needed for the rational design of pH-sensitive cationic lipid structures and the selection of appropriate helper lipids and will facilitate the development of highly potent small-sized LNPs. STATEMENT OF SIGNIFICANCE: Despite the fact that small-sized lipid nanoparticles (LNPs) are important for improved tissue penetration and efficient drug delivery, the size reduction-associated decrease in the stability and intracellular trafficking significantly hinders the development of potent small-sized LNPs. Our limited understanding of the mechanism underlying the reduced potency has also hindered the development of more potent small-sized LNPs. The findings of the present study indicate that long and linear hydrophobic scaffolds of pH-sensitive cationic lipids could overcome the loss of efficiency for nucleic acid delivery. In addition, the long hydrophobic scaffolds led to immiscibility with neutral phospholipids, resulting in efficient endosomal escape. These findings provide useful information needed for the rational design of pH-sensitive cationic lipid structures and will facilitate the development of highly potent small-sized LNPs.
  • Development of a Paper-based Analytical Chip for the Detection of Bacterial 16S rRNA in Wastewater Samples
    Meri Nakajima, Akihiko Ishida, Manabu Tokeshi, Hisashi Satoh
    BUNSEKI KAGAKU, 69, 12, 715, 722, 2020, [Peer-reviewed]
    Japanese, Scientific journal
  • Development of an immuno-wall device for the rapid and sensitive detection of EGFR mutations in tumor tissues resected from lung cancer patients.
    Naoyuki Yogo, Tetsunari Hase, Toshihiro Kasama, Keine Nishiyama, Naoya Ozawa, Takahiro Hatta, Hirofumi Shibata, Mitsuo Sato, Kazuki Komeda, Nozomi Kawabe, Kohei Matsuoka, Toyofumi Fengshi Chen-Yoshikawa, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba, Yoshinori Hasegawa
    PloS One, 15, 11, e0241422, 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Detecting molecular targets in specimens from patients with lung cancer is essential for targeted therapy. Recently, we developed a highly sensitive, rapid-detection device (an immuno-wall device) that utilizes photoreactive polyvinyl alcohol immobilized with antibodies against a target protein via a streptavidin-biotin interaction. To evaluate its performance, we assayed epidermal growth factor receptor (EGFR) mutations, such as E746_A750 deletion in exon 19 or L858R substitution in exon 21, both of which are common in non-small cell lung cancer and important predictors of the treatment efficacy of EGFR tyrosine kinase inhibitors. The results showed that in 20-min assays, the devices detected as few as 1% (E746_A750 deletion) and 0.1% (L858R substitution) of mutant cells. Subsequent evaluation of detection of the mutations in surgically resected lung cancer specimens from patients with or without EGFR mutations and previously diagnosed using commercially available, clinically approved genotyping assays revealed diagnostic sensitivities of the immuno-wall device for E746_A750 deletion and L858R substitution of 85.7% and 87.5%, respectively, with specificities of 100% for both mutations. These results suggest that the immuno-wall device represents a good candidate next-generation diagnostic tool, especially for screening of EGFR mutations.
  • An Electrochemical Sensor Based on Structure Switching of Dithiol-modified Aptamer for Simple Detection of Ochratoxin A.
    Donny Nugraha Mazaafrianto, Akihiko Ishida, Masatoshi Maeki, Hirofumi Tani, Manabu Tokeshi
    Analytical Sciences, 35, 11, 1221, 1226, 10 Nov. 2019, [Peer-reviewed], [Last author, Corresponding author], [Domestic magazines]
    English, Scientific journal, In this study, we developed an electrochemical sensor for ochratoxin A (OTA) by using an aptamer having a dithiol-based anchor, which exhibited higher stability on a gold electrode than a monothiol-based aptamer because of its two anchors. The sensor was also based on a signal-on scheme that produces a signal current resulting from structure-switching of the aptamer upon interaction with OTA. For simple fabrication of this sensor, the non-covalent interaction of methylene blue with the aptamer was also employed as an electrochemical indicator. In this study, the performance of the sensor, including the dissociation constant of the aptamer-OTA complex, was characterized. The proposed sensor exhibited high reproducibility and enough sensitivity to detect the minimum amount of OTA required for the analysis of real food samples with a limit of detection of 113 pM.
  • A paper-based analytical device coupled with electrochemical detection for the determination of dexamethasone and prednisolone in adulterated traditional medicines.
    Vitsarut Primpray, Orawon Chailapakul, Manabu Tokeshi, Theerasak Rojanarata, Wanida Laiwattanapaisal
    Analytica Chimica Acta, 1078, 16, 23, 31 Oct. 2019, [Peer-reviewed], [Internationally co-authored], [International Magazine]
    English, Scientific journal, The adulteration of herbal medicines by dexamethasone or prednisolone is regarded as a serious problem in many communities. Herein, a novel platform for the separation and quantification of both target steroids in herbal medicines based on electrochemical paper-based analytical devices (ePADs) has been created. The ePAD was composed of Whatman SG81 chromatography paper, 3D-printed devices and a commercial screen-printed electrode. Whatman SG81 silica-coated paper was used for the separation of dexamethasone and prednisolone based on the difference in their partition coefficients during the flow of the mobile phase. The optimal mobile phase was composed of 60% ethyl acetate in cyclohexane and required 7 min for separation. The separated steroids on the paper were then quantified by electrochemical detection using differential pulse voltammetry, in which the 3D-printed devices facilitated the measurement. Analytical detection ranges of 10-500 μg mL-1 were obtained for both dexamethasone and prednisolone (r2 = 0.988 and 0.994, respectively). The limits of detection for dexamethasone and prednisolone were 3.59 and 11.98 μg mL-1, respectively, whereas the limits of quantification were 6.00 and 20.02 μg mL-1, respectively. The amounts of both target steroids derived from real herbal medicine samples determined by the proposed method were comparable to those obtained with assays using standard high-performance liquid chromatography. In addition, a simple evaporation step can be used to increase the concentration of the samples before analysis. These ePADs are simple, low-cost, rapid, and very promising for on-site quantitative detection.
  • Rapid, Sensitive, and Selective Detection of H5 Hemagglutinin from Avian Influenza Virus Using an Immunowall Device.
    Kenia Chávez Ramos, Keine Nishiyama, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Toshihiro Kasama, Yoshinobu Baba, Manabu Tokeshi
    ACS Omega, 4, 15, 16683, 16688, 08 Oct. 2019, [Peer-reviewed], [Last author, Corresponding author], [Internationally co-authored], [International Magazine]
    English, Scientific journal, Avian influenza virus (AIV) infection, caused by influenza virus type A, is an infectious, acute respiratory disease of birds related to influenza outbreaks worldwide. The highly pathogenic AIV subtype H5N1 has crossed species barriers to infect mammals, including humans, with fatal outcomes and has received attention as a potential pandemic threat. A rapid and timely detection in poultry is vitally important to prevent the virus spread. Despite their great sensitivity, conventional detection methods such as real-time reverse transcription-polymerase chain reaction and the agar gel precipitation test are time-consuming and labor-intensive and require special training. In this work, an immunowall device was evaluated as an easier and faster way for detecting AIV H5-hemagglutinin (AIV H5-HA). For detection, fluorescence-labeled or enzyme-labeled antibody was employed as a labeling antibody in a sandwich immunoassay. Both were shown in this paper to be easier and faster assays for detection compared with the conventional enzyme-linked immunosorbent assay (ELISA) kit. In addition, high selectivity was achieved for AIV H5-HA detection after the evaluation of other different HA virus subtypes. The limit of detection was 0.23 ng/mL for the enzyme-labeled antibody. This value was equivalent to that of the conventional ELISA kit but 8 times faster (31 min compared to 260 min). The detection range was 0.23-100 ng/mL. The immunowall device with the enzyme-labeled antibody offers a rapid, sensitive, selective, and simple immunoassay system for future H5 AIV real sample detection.
  • High-throughput fluorescence polarization immunoassay by using a portable fluorescence polarization imaging analyzer.
    Osamu Wakao, Ken Satou, Ayano Nakamura, Polina A Galkina, Keine Nishiyama, Ken Sumiyoshi, Fumio Kurosawa, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Mikhail A Proskurnin, Koji Shigemura, Akihide Hibara, Manabu Tokeshi
    Lab on a Chip, 19, 15, 2581, 2588, 07 Aug. 2019, [Peer-reviewed], [Last author, Corresponding author], [Internationally co-authored], [International Magazine]
    English, Scientific journal, High-throughput fluorescence polarization immunoassays (FPIAs) for mycotoxin were conducted using a portable FP analyzer with a microdevice. Simultaneous FPIA measurements for 8 different deoxynivalenol (DON) concentrations in 12 chambers (total of 96 samples) and high-throughput FPIA measurements for single DON concentrations in more than 500 chambers were conducted. The results indicated that simultaneous FPIAs for 96 independent samples and for 500 samples were possible by FP imaging. The FP analyzer has a size of 65 cm (W 35 cm × D 15 cm × H 15 cm) and costs less than $5000. The sample volume was 1 nL. Furthermore, it is expected that sample reaction and FP detection can be automatically conducted with the analyzer by changing the microdevice and the software. Its features such as low cost and portability will contribute to on-site measurement and point-of-care testing. Additionally, the high-throughput feature will contribute to the study of molecular interactions based on FP measurements.
  • Ultrasensitive detection of disease biomarkers using an immuno-wall device with enzymatic amplification.
    Keine Nishiyama, Toshihiro Kasama, Seiya Nakamata, Koya Ishikawa, Daisuke Onoshima, Hiroshi Yukawa, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Yoshinobu Baba, Manabu Tokeshi
    The Analyst, 144, 15, 4589, 4595, 07 Aug. 2019, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
    English, Scientific journal, We present an ultrasensitive immunoassay system for disease biomarkers utilizing the immuno-wall device and an enzymatic amplification reaction. The immuno-wall device consisted of 40 microchannels, each of which contained an antibody-modified wall-like structure along the longitudinal axis of the microchannel. The wall was fabricated with a water-soluble photopolymer containing streptavidin by photolithography, and biotinylated capture antibodies were immobilized on the sides through streptavidin-biotin interaction. For an assay, introducing the target biomarker and secondary and labeled antibodies produced a sandwich complex anchored on the sides of the wall. A conventional immuno-wall device uses a fluorescence-labeled antibody as a labeling antibody. To achieve an ultrasensitive detection of a trace biomarker, we used an enzyme label and amplified the signal with the enzymatic reaction with a fluorogenic substrate in the microchannel. The highest signal/background ratio was obtained by using alkaline phosphatase-labeled antibody and 9H-(1,3-dichloro-9,9-dimethylacridin-2-one-7-yl) phosphate. To evaluate the device performance, we detected human C-reactive protein (CRP) as a model biomarker. The detection limit (LOD) of CRP in phosphate-buffered saline was 2.5 pg mL-1 with a sample volume of 0.25 μL. This LOD was approximately 3 orders of magnitude lower than that obtained with fluorescent-dye (DyLight 650)-labeled antibody. In addition, the present device provided a wide detection range of 0.0025-10 ng mL-1 for CRP. We successfully developed an ultrasensitive immunoassay system with simple operation and only a small sample volume.
  • The Use of a Microfluidic Device to Encapsulate a Poorly Water-Soluble Drug CoQ10 in Lipid Nanoparticles and an Attempt to Regulate Intracellular Trafficking to Reach Mitochondria.
    Mitsue Hibino, Yuma Yamada, Naoki Fujishita, Yusuke Sato, Masatoshi Maeki, Manabu Tokeshi, Hideyoshi Harashima
    Journal of Pharmaceutical Sciences, 108, 8, 2668, 2676, Aug. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal, A number of drugs that are currently on the market, as well as new candidates for drugs, are poorly water soluble. Because of this, a need exists to develop drug formulations that will permit the expanded use of such drugs. The use of liposomes and lipid nanoparticles for drug delivery has attracted attention as a technique for solubilizing molecules that are poorly water soluble, but this technique faces serious scale-up risks. In this study, we report on attempts to encapsulate Coenzyme Q10 (CoQ10) as a model of a poorly water-soluble drug in an MITO-Porter, a liposome for mitochondrial delivery using a microfluidic device (a CoQ10-MITO-Porter [μ]). The physical properties of the CoQ10-MITO-Porter [μ] including homogeneity, size, and preparation volume were compared with those for a CoQ10-MITO-Porter prepared by the ethanol dilution method (a CoQ10-MITO-Porter [ED]). In the case where a microfluidic device was used, a small-sized CoQ10-MITO-Porter was formed homogeneously, and it was possible to prepare it on a large scale. Intracellular observations using HeLa cells showed that the CoQ10-MITO-Porter [μ] was efficiently internalized by cells to reach mitochondria. These results indicate that the CoQ10-MITO-Porter [μ] represents a potential candidate for use in mitochondrial nanomedicine.
  • A Concentric Ring Array Electrode for a Wall-Jet Cell in a Microfluidic Device               
    Keine Nishiyama, Koki Hoshikawa, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Electroanalysis, 31, 1736, 1743, Jun. 2019, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Sensitive Fluorescent Polarization Immunoassay by Optimizing Synchronization Mismatch Condition
    Osamu Wakao, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Akihide Hibara, Manabu Tokeshi
    Sensors and Actuators B, 285, 418, 422, Apr. 2019, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Understanding structure-activity relationships of pH-sensitive cationic lipids facilitates the rational identification of promising lipid nanoparticles for delivering siRNAs in vivo
    Yusuke Sato, Kazuki Hashiba, Kosuke Sasaki, Masatoshi Maeki, Manabu Tokeshi, Hideyoshi Harashima
    Journal of Controlled Release, 295, 140, 152, Elsevier BV, Feb. 2019, [Peer-reviewed]
    English, Scientific journal
  • Development of a Microdevice for Facile Analysis of Theophylline in Whole Blood by a Cloned Enzyme Donor Immunoassay               
    Keine Nishiyama, Kanako Sugimura, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Lab on a Chip, 19, 233, 240, Feb. 2019, [Peer-reviewed], [Corresponding author]
    English, Scientific journal
  • Label-Free Electrochemical Sensor for Ochratoxin A Uisng a Microfabricated Electrode with Immobilized Aptamer
    Donny N. Mazaafrianto, Akihiko Ishida, Masatoshi Maeki, Hirofumi Tani, Manabu Tokeshi
    ACS Omega, 3, 12, 16823, 16830, American Chemical Society (ACS), Dec. 2018, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Development of the iLiNP Device: Fine Tuning the Lipid Nanoparticle Size within 10 nm for Drug Delivery
    Niko Kimura, Masatoshi Maeki, Yusuke Sato, Yusuke Note, Akihiko Ishida, Hirofumi Tani, Hideyoshi Harashima, Manabu Tokeshi
    ACS Omega, 3, 5, 5044, 5051, American Chemical Society, 09 May 2018, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Recent Microdevice-based Aptamer Sensors
    Manabu Tokeshi
    Micromachines, 9, 5, 1, 25, MDPI AG, Apr. 2018, [Peer-reviewed], [Invited], [Last author, Corresponding author]
    English, Scientific journal, Since the systematic evolution of ligands by exponential enrichment (SELEX) method was developed, aptamers have made significant contributions as bio-recognition sensors. Microdevice systems allow for low reagent consumption, high-throughput of samples, and disposability. Due to these advantages, there has been an increasing demand to develop microfluidic-based aptasensors for analytical technique applications. This review introduces the principal concepts of aptasensors and then presents some advanced applications of microdevice-based aptasensors on several platforms. Highly sensitive detection techniques, such as electrochemical and optical detection, have been integrated into lab-on-a-chip devices and researchers have moved towards the goal of establishing point-of-care diagnoses for target analyses.
  • Microfluidic Devices for Drug Delivery Systems
    Manabu Tokeshi
    Advanced Drug Delivery Reviews, 128, 1, 2, Elsevier B.V., 15 Mar. 2018, [Peer-reviewed], [Invited], [Corresponding author]
    English, Scientific journal
  • Advances in microfluidics for lipid nanoparticles and extracellular vesicles and applications in drug delivery systems
    Masatoshi Maeki, Niko Kimura, Yusuke Sato, Hideyoshi Harashima, Manabu Tokeshi
    Advanced Drug Delivery Reviews, 128, 84, 100, Elsevier B.V., 15 Mar. 2018, [Peer-reviewed], [Invited], [Last author, Corresponding author]
    English, Scientific journal
  • A compact fluorescence polarization analyzer with high-transmittance liquid crystal layer
    Osamu Wakao, Ken Satou, Ayano Nakamura, Ken Sumiyoshi, Masanori Shirokawa, Chikaaki Mizokuchi, Kunihiro Shiota, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Koji Shigemura, Akihide Hibara, Manabu Tokeshi
    Review of Scientific Instruments, 89, 2, 024103, American Institute of Physics Inc., 01 Feb. 2018, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Characteristics of microfluidic paper-based analytical devices fabricated by four different methods
    Takeshi Komatsu, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Analytical Sciences, 34, 1, 39, 44, Japan Society for Analytical Chemistry, 2018, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Dynamic wettability of polyethylene glycol-modified poly(dimethylsiloxane) surfaces in an aqueous/organic two-phase system
    Mao Fukuyama, Manabu Tokeshi, Mikhail A. Proskurnin, Akihide Hibara
    Lab on a Chip, 18, 2, 356, 361, Royal Society of Chemistry, 2018, [Peer-reviewed], [Internationally co-authored]
    English, Scientific journal
  • マイクロデバイスを用いたタンパク質の立体構造解析
    真栄城 正寿, 宮崎 真佐也, 渡慶次 学
    ぶんせき, 516, 575, 580, (公社)日本分析化学会, Dec. 2017
    Japanese
  • Understanding the formation mechanism of lipid nanoparticles in microfluidic devices with chaotic micromixers
    Masatoshi Maeki, Yuka Fujishima, Yusuke Sato, Takao Yasui, Noritada Kaji, Akihiko Ishida, Hirofumi Tani, Yoshinobu Baba, Hideyoshi Harashima, Manabu Tokeshi
    PLoS ONE, 12, 11, e0187962, Nov. 2017, [Peer-reviewed], [Corresponding author]
    English, Scientific journal
  • Using Laser Interference Lithography in the Fabrication of a Simplified Micro and Nanofluidic Device for Label-free Detection
    Taiga Ajiri, Haruya Kasa, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Junji Nishi, Manabu Tokeshi
    Analytical Sciences, 33, 10, 1197, 1199, Oct. 2017, [Peer-reviewed], [Corresponding author]
    English, Scientific journal
  • Optimization of the nanofluidic design for label-free detection of biomolecules using a nanowall array
    Taiga Ajiri, Takao Yasui, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Yoshinobu Baba, Manabu Tokeshi
    Sensors and Actuators B-Chemical, 250, 39, 43, Oct. 2017, [Peer-reviewed], [Corresponding author]
    English, Scientific journal
  • 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, Mar. 2017, [Peer-reviewed]
    English, Scientific journal
  • Rapid Detection of Cat Cystatin C (cCys-C) Using Immuno-Pillar Chips
    Saeed Mohammadi, Lori Shayne Alamo Busa, Masatoshi Maeki, Reza M. Mohamadi, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Analytical Sciences, 32, 12, 1359, 1362, Dec. 2016, [Peer-reviewed]
    English, Scientific journal
  • Novel concept of washing for microfluidic paper-based analytical devices based on capillary force of paper substrates
    Saeed Mohammadi, Lori Shayne Alamo Busa, Masatoshi Maeki, Reza M. Mohamadi, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Analytical and Bioanalytical Chemistry, 408, 27, 7559, 7563, Nov. 2016, [Peer-reviewed]
    English, Scientific journal
  • Simple and sensitive colorimetric assay system for horseradish peroxidase using microfluidic paper-based devices
    Lori Shayne Alamo Busa, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Sensors and Actuators B: Chemical, 236, 433, 441, Nov. 2016
    English, Scientific journal
  • Label-free detection of real-time DNA amplification using a nanofluidic diffraction grating
    Takao Yasui, Kensuke Ogawa, Noritada Kaji, Mats Nilsson, Taiga Ajiri, Manabu Tokeshi, Yasuhiro Horiike, Yoshinobu Baba
    Scientific Reports, 6, 31642, Aug. 2016, [Peer-reviewed]
    English, Scientific journal
  • 3,3 ',5,5 '-Tetramethylbenzidine Oxidation on Paper Devices for Horseradish Peroxidase-based Assays
    Lori Shayne Alamo Busa, Takeshi Komatsu, Saeed Mohammadi, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    ANALYTICAL SCIENCES, 32, 8, 815, 818, Aug. 2016, [Peer-reviewed]
    English, Scientific journal
  • Microfluidic Autologous Serum Eye-Drops Preparation as a Potential Dry Eye Treatment
    Takao Yasui, Jumpei Morikawa, Noritada Kaji, Manabu Tokeshi, Kazuo Tsubota, Yoshinobu Baba
    Micromachines, 7, 7, 113, Jul. 2016, [Peer-reviewed]
    English, Scientific journal
  • Elucidation of the physicochemical properties and potency of siRNA-loaded small-sized lipid nanoparticles for siRNA delivery
    Yusuke Sato, Yusuke Note, Masatoshi Maeki, Noritada Kaji, Yoshinobu Baba, Manabu Tokeshi, Hideyoshi Harashima
    Journal of Controlled Release, 229, 48, 57, May 2016, [Peer-reviewed]
    English, Scientific journal
  • An Easy-to-Use Polystyrene Microchip-based Cell Culture System
    Hidekatsu Tazawa, Shohei Sunaoshi, Manabu Tokeshi, Takehiko Kitamori, Ritsuko Ohtani-Kaneko
    Analytical Sciences, 32, 3, 349, 353, Mar. 2016, [Peer-reviewed]
    English, Scientific journal
  • Microfluidic Autologous Serum Eye-Drops Preparation as a Potential Dry Eye Treatment.
    Takao Yasui, Jumpei Morikawa, Noritada Kaji, Manabu Tokeshi, Kazuo Tsubota, Yoshinobu Baba
    Micromachines, 7, 7, 113, 113, 2016, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Advances in microfluidic paper-based analytical devices for food and water analysis
    Lori Shayne Alamo Busa, Saeed Mohammadi, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Micromachines, 7, 5, 1, 21, MDPI AG, 2016, [Peer-reviewed], [Last author, Corresponding author]
    English, Scientific journal
  • Microfluidic approaches for protein crystal structure analysis
    Masatoshi Maeki, Hiroshi Yamaguchi, Manabu Tokeshi, Masaya Miyazaki
    Analytical Sciences, 32, 1, 3, 9, Japan Society for Analytical Chemistry, 2016, [Peer-reviewed]
    English, Scientific journal
  • A competitive immunoassay system for microfluidic paper-based analytical detection of small size molecules
    Lori Shayne Alamo Busa, Saeed Mohammadi, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Analyst, 141, 24, 6598, 6603, 2016, [Peer-reviewed]
    English, Scientific journal
  • Image analysis for a microfluidic paper-based analytical device using the CIE L(star)a(star)b(star) color system
    Takeshi Komatsu, Saeed Mohammadi, Lori Shayne Alamo Busa, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Analyst, 141, 24, 6507, 6509, 2016, [Peer-reviewed]
    English, Scientific journal
  • A microfluidic-based protein crystallization method in 10 micrometer-sized crystallization space
    Masatoshi Maeki, Shohei Yamazaki, Ashtamurthy S. Pawate, Akihiko Ishida, Hirofumi Tani, Kenichi Yamashita, Masakazu Sugishima, Keiichi Watanabe, Manabu Tokeshi, Paul J. A. Kenis, Masaya Miyazaki
    CrystEngComm, 18, 40, 7722, 7727, 2016, [Peer-reviewed]
    English, Scientific journal
  • An immuno-wall microdevice exhibits rapid and sensitive detection of IDH1-R132H mutation specific to grade II and III gliomas
    Akane Yamamichi, Toshihiro Kasama, Fumiharu Ohka, Hiromichi Suzuki, Akira Kato, Kazuya Motomura, Masaki Hirano, Melissa Ranjit, Lushun Chalise, Michihiro Kurimoto, Goro Kondo, Kosuke Aoki, Noritada Kaji, Manabu Tokeshi, Toshio Matsubara, Takeshi Senga, Mika K. Kaneko, Hidenori Suzuki, Masahito Hara, Toshihiko Wakabayashi, Yoshinobu Baba, Yukinari Kato, Atsushi Natsume
    Science and Technology of Advanced Materials, 17, 1, 618, 625, 2016, [Peer-reviewed]
    English, Scientific journal
  • A Portable Liquid Chromatograph with a Battery-operated Compact Electroosmotic Pump and a Microfluidic Chip Device with a Reversed Phase Packed Column
    Akihiko Ishida, Mitsutaka Fujii, Takehiro Fujimoto, Shunsuke Sasaki, Ichiro Yanagisawa, Hirofumi Tani, Manabu Tokeshi
    Analytical Sciences, 31, 11, 1163, 1169, 10 Nov. 2015, [Peer-reviewed]
    English, Scientific journal
  • Micropillars Fabricated on Poly(methyl methacrylate) Substrates for Separation of Microscale Objects
    Takao Yasui, Satoru Ito, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Sciences, 31, 11, 1197, 1200, Nov. 2015, [Peer-reviewed]
    English, Scientific journal
  • Fluorescence Polarization Measurement System Using a Liquid Crystal Layer and an Image Sensor
    Osamu Wakao, Yusaku Fujii, Masatoshi Maeki, Akihiko Ishida, Hirofumi Tani, Akihide Hibara, Manabu Tokeshi
    Analytical Chemistry, 87, 19, 9647, 9652, Oct. 2015, [Peer-reviewed]
    English, Scientific journal
  • A microfluidic cell culture system for monitoring of sequential changes in endothelial cells after heat stress
    Hidekatsu Tazawa, Kenjiro Sato, Atsuhiro Tsutiya, Manabu Tokeshi, Ritsuko Ohtani-Kaneko
    Thrombosis Research, 136, 2, 328, 334, Aug. 2015, [Peer-reviewed]
    English, Scientific journal
  • Arrangement of a Nanostructure Array To Control Equilibrium and Nonequilibrium Transports of Macromolecules
    Takao Yasui, Noritada Kaji, Ryo Ogawa, Shingi Hashioka, Manabu Tokeshi, Yasuhiro Horiike, Yoshinobu Baba
    Nano Letters, 15, 5, 3445, 3451, May 2015, [Peer-reviewed]
    English, Scientific journal
  • A Method of Cryoprotection for Protein Crystallography by Using a Microfluidic Chip and Its Application for in Situ X-ray Diffraction Measurements
    Masatoshi Maeki, Ashtamurthy S. Pawate, Kenichi Yamashita, Masahide Kawamoto, Manabu Tokeshi, Paul J. A. Kenis, Masaya Miyazaki
    Analytical Chemistry, 87, 8, 4194, 4200, Apr. 2015, [Peer-reviewed]
    English, Scientific journal
  • An instrument-free, screen-printed paper microfluidic device that enables bio and chemical sensing
    Saeed Mohammadi, Masatoshi Maeki, Reza M. Mohamadi, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Analyst, 140, 19, 6493, 6499, 2015, [Peer-reviewed]
    English, Scientific journal
  • Hydrodynamic nonadhesive cell retention in a microfluidic circuit for stressless suspension culture
    Toyohito Naito, Noritada Kaji, Manabu Tokeshi, Takuya Kubo, Yoshinobu Baba, Koji Otsuka
    Analytical Methods, 7, 17, 7264, 7269, 2015, [Peer-reviewed]
    English, Scientific journal
  • Rapid, highly sensitive, and simultaneous detection of staphylococcal enterotoxins in milk by using immuno-pillar devices
    Toshihiro Kasama, Mai Ikami, Wanchun Jin, Keiko Yamada, Noritada Kaji, Yusuke Atsumi, Makoto Mizutani, Atsushi Murai, Akira Okamoto, Takao Namikawa, Michio Ohta, Manabu Tokeshi, Yoshinobu Baba
    Analytical Methods, 7, 12, 5092, 5095, 2015, [Peer-reviewed]
    English, Scientific journal
  • A strategy for synthesis of lipid nanoparticles using microfluidic devices with a mixer structure
    Masatoshi Maeki, Tatsuyoshi Saito, Yusuke Sato, Takao Yasui, Noritada Kaji, Akihiko Ishida, Hirofumi Tani, Yoshinobu Baba, Hideyoshi Harashima, Manabu Tokeshi
    RSC Advances, 5, 57, 46181, 46185, 2015, [Peer-reviewed]
    English, Scientific journal
  • Development of High-performance Immuno-pillar Devices: Improvement of Antibody-immobilized Solid Support
    NISHIWAKI Nanako, KASAMA Toshihiro, ISHIDA Akihiko, TANI Hirofumi, BABA Yoshinobu, TOKESHI Manabu
    BUNSEKI KAGAKU, 64, 5, 329, 335, Japan Society for Analytical Chemistry, 2015, [Peer-reviewed]
    Japanese, Scientific journal, In order to realize ultra-early diagnosis of disease in practical applications, we have fabricated next-generation immuno-pillar devices with higher sensitivity. In the newly developed devices, capture antibodies were immobilized on affinity beads based on chemical bonding, while in the previous-generation ones, polystyrene beads were used for physical adsorption-based immobilization. To evaluate the sensitivity of the next-generation immuno-pillar device, we quantitatively analyzed C-reactive protein (CRP). The limit of detection was estimated to be 0.1 ng mL−1 (total assay time, 23 min), which was twoorders of magnitude lower than that obtained by using the previous-generation immuno-pillar device, and was low enough to perform the CRP test. In addition, we investigated the storage stability of the immuno-pillar device, and confirmed that the device can retain its performance for over 9 months.
  • Development of a Micro RNA Extraction Chip from Human Tumor Cells
    OKAMOTO Yukihiro, HIBINO Ayato, KAJI Noritada, TOKESHI Manabu, BABA Yoshinobu
    BUNSEKI KAGAKU, 64, 1, 9, 13, The Japan Society for Analytical Chemistry, 2015, [Peer-reviewed]
    Japanese, Scientific journal, The importance of micro RNA analysis has been significantly increasing because the role of micro RNA in the human body has been gradually revealed. Despite its importance, the analysis has suffered from several troublesome pretreatments, which hamper any easy analysis. Therefore, an easy and high-throughput pretreatment method has been demanded. In this paper, we focused on the great advantages of microchip pretreatments over conventional manual pretreatments and developed a microchip for micro RNA extraction. To simplify microchip fabrication, we adopted poly(dimethyl siloxane) (PDMS) microchip and a silica membrane, which has rolls in RNA extraction fields. With silica membranes and the adhesion nature of PDMS, we could easily fabricate RNA extraction fields in the microchip. With this microchip, we successfully extracted micro RNA from cancer tumor cells. Though this is a preliminary experiment, and still has many improvement points, our device is expected to be applied for easy and fast micro RNA extraction from biological samples.
  • Synthesis and Reactions of Ynolates via a Stop-Flow Method with a Flow Microreactor
    Toshiya Yoshiiwa, Satoshi Umezu, Manabu Tokeshi, Yoshinobu Baba, Mitsuru Shindo
    Journal of Flow Chemistry, 4, 4, 180, 184, Dec. 2014, [Peer-reviewed]
    English, Scientific journal
  • Bioluminescence immunoassay using luciferase-encapsulated liposome as a label
    Yusuke Nakatani, Chiaki Shido, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Luminescence, 29, 83, 84, Aug. 2014, [Peer-reviewed]
    English
  • Bioluminescence Assay Based on Controlled Inhibitory Effect on Firefly Luciferase
    Ryoko Kurishiba, Akihiko Ishida, Hirofumi Tani, Manabu Tokeshi
    Luminescence, 29, 78, 78, Aug. 2014, [Peer-reviewed]
    English
  • Effect of reductants on oscillatory chemiluminescence of fluorescein catalyzed by horseradish peroxidase
    Hirofumi Tani, Ai Masuyama, Akihiko Ishida, Manabu Tokeshi
    Luminescence, 29, 99, 100, Aug. 2014, [Peer-reviewed]
    English
  • Generation of ynolates via reductive lithiation using flow microreactors
    Satoshi Umezu, Toshiya Yoshiiwa, Manabu Tokeshi, Mitsuru Shindo
    Tetrahedron Letters, 55, 10, 1822, 1825, Mar. 2014, [Peer-reviewed]
    English, Scientific journal
  • Microfluidic biosensor for the detection of DNA by fluorescence enhancement and the following streptavidin detection by fluorescence quenching
    Jun Wang, Michihiko Aki, Daisuke Onoshima, Kenji Arinaga, Noritada Kaji, Manabu Tokeshi, Shozo Fujita, Naoki Yokoyama, Yoshinobu Baba
    Biosensors and Bioelectronics, 51, 280, 285, Jan. 2014, [Peer-reviewed]
    English, Scientific journal
  • Nanopillar array chip integrated with on-line stacking for fast DNA separation with high sensitivity and high resolution
    Takao Yasui, Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Yasuhiro Horiike, Yoshinobu Baba
    Microfluidics and Nanofluidics, 14, 6, 961, 967, Jun. 2013, [Peer-reviewed]
    English, Scientific journal
  • Highly efficient electrochemical valence control of uranium using microfluidic chip equipped with microelectrodes
    Takehiko Tsukahara, Hiroyasu Hotokezaka, Masayuki Harada, Yoshikuni Kikutani, Manabu Tokeshi, Yasuhisa Ikeda
    Microfluidics and Nanofluidics, 14, 6, 989, 994, Jun. 2013, [Peer-reviewed]
    English, Scientific journal
  • 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, Apr. 2013, [Peer-reviewed]
    English, Scientific journal
  • Parallel Real-Time PCR on a Chip for Genetic Tug-of-War (gTOW) Method
    Toyohiro Naito, Ai Yatsuhashi, Noritada Kaji, Taeko Ando, Kazuo Sato, Hisao Moriya, Hiroaki Kitano, Takao Yasui, Manabu Tokeshi, Yoshinobu Baba
    Analytical Sciences, 29, 3, 367, 371, Mar. 2013, [Peer-reviewed]
    English, Scientific journal
  • Application of IgY to sandwich enzyme-linked immunosorbent assays, lateral flow devices, and immunopillar chips for detecting staphylococcal enterotoxins in milk and dairy products.
    Wanchun Jin, Keiko Yamada, Mai Ikami, Noritada Kaji, Manabu Tokeshi, Yusuke Atsumi, Makoto Mizutani, Atsushi Murai, Akira Okamoto, Takao Namikawa, Yoshinobu Baba, Michio Ohta
    Journal of Microbiological Methods, 92, 3, 323, 31, Mar. 2013, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Staphylococcal enterotoxins (SEs), produced by Staphylococcus aureus, are a major cause of staphylococcal food poisoning. Traditionally, sandwich enzyme-linked immunosorbent assay (ELISA) and reverse passive latex agglutination with rabbit antibody IgG have been used to detect SEs. However, most of these kits require a long processing time and there is a risk of false-positive results since IgG reacts nonspecifically with protein A produced by S. aureus. In this study, we prepared antienterotoxin chicken IgY antibodies specific for each SE (SEA to SEE) without reaction to protein A, which enabled a drastic reduction in nonspecific reactions. ELISAs, lateral flow device (LFDs), and IgY-based immunopillar chips were developed for SE detection. All the ELISAs developed were as sensitive as commercially available kits. The SEs in milk were successfully detected by the ELISAs, LFDs, and immunopillar chips without any sample pretreatment. The LFD could detect SEA even at the low concentration of 0.2 ng/ml within 15 min in milk. The detection limit of the immunopillar chips for the SEs ranged from 0.01 to 0.1 ng/ml in milk; the SEs were detected within 12 min and specialized skills were not required. The ELISA and LFD detected SEA in dairy products artificially contaminated with S. aureus, including ice cream, yogurt, and café au lait, in a dose-dependent manner. In conclusion, IgY allows highly specific detection of SEs, and ELISAs, LFDs, and immunopillar chips should be useful tools for screening SEs in milk and dairy products.
  • Quantum Dots Conjugated with Transferrin for Brain Tumor Cell Imaging               
    Hiroshi Yukawa, Ryoko Tsukamoto, Ayano Kano, Yukihiro Okamoto, Manabu Tokeshi, Tetsuya Ishikawa, Masaaki Mizuno, Yoshinobu Baba
    Journal of Cell Science & Therapy, 4, 150-1, 150-7, 2013, [Peer-reviewed]
    English, Scientific journal
  • Enzyme-catalysed reaction for long-term fluorescent observation of single DNA molecules
    Takao Yasui, Koki Motoyama, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    RSC Advances, 3, 10, 3237, 3240, 2013, [Peer-reviewed]
    English, Scientific journal
  • Temperature-driven self-actuated microchamber sealing system for highly integrated microfluidic devices
    Toyohiro Naito, Rerngchai Arayanarakool, Severine Le Gac, Takao Yasui, Noritada Kaji, Manabu Tokeshi, Albert van den Berg, Yoshinobu Baba
    Lab on a Chip, 13, 3, 452, 458, 2013, [Peer-reviewed]
    English, Scientific journal
  • Inkjet Injection of DNA Droplets for Microchannel Array Electrophoresis
    Takao Yasui, Yosuke Inoue, Toyohiro Naito, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Chemistry, 84, 21, 9282, 9286, Nov. 2012, [Peer-reviewed]
    English, Scientific journal
  • Fabrication of Functionalized Double-Lamellar Multifunctional Envelope-Type Nanodevices Using a Microfluidic Chip with a Chaotic Mixer Array
    Katsuma Kitazoe, Yeon-Su Park, Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Kentaro Kogure, Hideyoshi Harashima, Yoshinobu Baba
    PLOS ONE, 7, 6, e39057-1, 8, Jun. 2012, [Peer-reviewed]
    English, Scientific journal
  • Monitoring transplanted adipose tissue-derived stem cells combined with heparin in the liver by fluorescence imaging using quantum dots
    Hiroshi Yukawa, Masaki Watanabe, Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Yoshitaka Miyamoto, Hirofumi Noguchi, Yoshinobu Baba, Shuji Hayashi
    Biomaterials, 33, 7, 2177, 2186, Mar. 2012, [Peer-reviewed]
    English, Scientific journal
  • Introducing carbon nanotubes into living walled plant cells through cellulase-induced nanoholes
    Maged F. Serag, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    RSC Advances, 2, 2, 398, 400, 2012, [Peer-reviewed]
    English, Scientific journal
  • Confocal Microscopic Evaluation of Mixing Performance for Three-Dimensional Microfluidic Mixer
    Takao Yasui, Yusuke Omoto, Keiko Osato, Noritada Kaji, Norikazu Suzuki, Toyohiro Naito, Yukihiro Okamoto, Manabu Tokeshi, Eiji Shamoto, Yoshinobu Baba
    Analytical Sciences, 28, 1, 57, 59, Jan. 2012, [Peer-reviewed]
    English, Scientific journal
  • The plant cell uses carbon nanotubes to build tracheary elements
    Maged F. Serag, Noritada Kaji, Manabu Tokeshi, Alberto Bianco, Yoshinobu Baba
    Integrative Biology, 4, 2, 127, 131, 2012, [Peer-reviewed]
    English, Scientific journal
  • Aqueous Phase Synthesized CdSe Magic-Sized Clusters: Solution Composition Dependence of Adsorption Layer Structure
    Yeon-Su Park, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Journal of Nanoscience and Nanotechnology, 12, 1, 539, 546, Jan. 2012, [Peer-reviewed]
    English, Scientific journal
  • A deep microfluidic absorbance detection cell replicated from a thickly stacked SU-8 dry film resist mold
    Daisuke Onoshima, Jun Wang, Michihiko Aki, Kenji Arinaga, Noritada Kaji, Manabu Tokeshi, Shozo Fujita, Naoki Yokoyama, Yoshinobu Baba
    Analytical Methods, 4, 12, 4368, 4372, 2012, [Peer-reviewed]
    English, Scientific journal
  • Characterization of low viscosity polymer solutions for microchip electrophoresis of non-denatured proteins on plastic chips
    Takao Yasui, Mohamad Reza Mohamadi, Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Yoshinobu Baba
    Biomicrofluidics, 5, 4, 044114-1, 9, Dec. 2011, [Peer-reviewed]
    English, Scientific journal
  • Estimation of the Distribution of Intravenously Injected Adipose Tissue-Derived Stem Cells Labeled with Quantum Dots in Mice Organs through the Determination of their Metallic Components by ICPMS
    Yuka Takasaki, Masaki Watanabe, Hiroshi Yukawa, Akhmad Sabarudin, Kazumi Inagaki, Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Yoshitaka Miyamoto, Hirofumi Noguchi, Tomonari Umemura, Shuji Hayashi, Yoshinobu Baba, Hiroki Haraguchi
    Analytical Chemistry, 83, 21, 8252, 8258, Nov. 2011, [Peer-reviewed]
    English, Scientific journal
  • Rapid qualitative evaluation of DNA transcription factor NF-kappa B by microchip electrophoretic mobility shift assay in mammalian cells
    Sonoko Inoue, Noritada Kaji, Masatoshi Kataoka, Yasuo Shinohara, Yukihiro Okamoto, Manabu Tokeshi, Yoshinobu Baba
    ELECTROPHORESIS, 32, 22, 3241, 3247, Nov. 2011, [Peer-reviewed]
    English, Scientific journal
  • Functional Platform for Controlled Subcellular Distribution of Carbon Nanotubes
    Maged F. Serag, Noritada Kaji, Enrica Venturelli, Yukihiro Okamoto, Kazuyoshi Terasaka, Manabu Tokeshi, Hajime Mizukami, Kevin Braeckmans, Alberto Bianco, Yoshinobu Baba
    ACS Nano, 5, 11, 9264, 9270, Nov. 2011, [Peer-reviewed]
    English, Scientific journal
  • Aqueous phase-synthesized small CdSe quantum dots: adsorption layer structure and strong band-edge and surface trap emission
    Yeon-Su Park, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Journal of Nanoparticle Research, 13, 11, 5781, 5798, Nov. 2011, [Peer-reviewed]
    English, Scientific journal
  • Extraction of Am(III) at the Interface of Organic-Aqueous Two-Layer Flow in a Microchannel
    Yasutoshi Ban, Yoshikuni Kikutani, Manabu Tokeshi, Yasuji Morita
    Journal of Nuclear Science and Technology, 48, 10, 1313, 1318, Oct. 2011, [Peer-reviewed]
    English, Scientific journal
  • A clinical trial for therapeutic drug monitoring using microchip-based fluorescence polarization immunoassay
    Tomoya Tachi, Tetsunari Hase, Yukihiro Okamoto, Noritada Kaji, Takeshi Arima, Hiroyuki Matsumoto, Masashi Kondo, Manabu Tokeshi, Yoshinori Hasegawa, Yoshinobu Baba
    Analytical and Bioanalytical Chemistry, 401, 7, 2301, 2305, Oct. 2011, [Peer-reviewed]
    English, Scientific journal
  • Electroosmotic Flow in Microchannels with Nanostructures
    Takao Yasui, Noritada Kaji, Mohamad Reza Mohamadi, Yukihiro Okamoto, Manabu Tokeshi, Yasuhiro Horiike, Yoshinobu Baba
    ACS Nano, 5, 10, 7775, 7780, Oct. 2011, [Peer-reviewed]
    English, Scientific journal
  • DNA Separation in Nanowall Array Chips
    Takao Yasui, Noritada Kaji, Ryo Ogawa, Shingi Hashioka, Manabu Tokeshi, Yasuhiro Horiike, Yoshinobu Baba
    Analytical Chemistry, 83, 17, 6635, 6640, Sep. 2011, [Peer-reviewed]
    English, Scientific journal
  • Label-Free Detection of DNA-Binding Proteins Based on Microfluidic Solid-State Molecular Beacon Sensor
    Jun Wang, Daisuke Onoshima, Michihiko Aki, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Chemistry, 83, 9, 3528, 3532, May 2011, [Peer-reviewed]
    English, Scientific journal
  • Trafficking and Subcellular Localization of Multiwalled Carbon Nanotubes in Plant Cells
    Maged F. Serag, Noritada Kaji, Claire Gaillard, Yukihiro Okamoto, Kazuyoshi Terasaka, Mohammad Jabasini, Manabu Tokeshi, Hajime Mizukami, Alberto Bianco, Yoshinobu Baba
    ACS Nano, 5, 1, 493, 499, Jan. 2011, [Peer-reviewed]
    English, Scientific journal
  • Online transient isotachophoresis concentration by the pseudo-terminating electrolyte buffer for the separation of DNA-aptamer and its thrombin complex in poly(methyl methacrylate) microchip
    Jun Wang, Yong Zhang, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analyst, 136, 6, 1142, 1147, 2011, [Peer-reviewed]
    English, Scientific journal
  • Thermal lens detection device
    Kazuma Mawatari, Toshinori Ohashi, Tomohiko Ebata, Manabu Tokeshi, Takehiko Kitamori
    Lab on a Chip, 11, 17, 2990, 2993, 2011, [Peer-reviewed]
    English, Scientific journal
  • A touch-and-go lipid wrapping technique in microfluidic channels for rapid fabrication of multifunctional envelope-type gene delivery nanodevices
    Katsuma Kitazoe, Jun Wang, Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Kentaro Kogure, Hideyoshi Harashima, Yoshinobu Baba
    Lab on a Chip, 11, 19, 3256, 3262, 2011, [Peer-reviewed]
    English, Scientific journal
  • Microfluidic baker's transformation device for three-dimensional rapid mixing
    Takao Yasui, Yusuke Omoto, Keiko Osato, Noritada Kaji, Norikazu Suzuki, Toyohiro Naito, Masaki Watanabe, Yukihiro Okamoto, Manabu Tokeshi, Eiji Shamoto, Yoshinobu Baba
    Lab on a Chip, 11, 19, 3356, 3360, 2011, [Peer-reviewed]
    English, Scientific journal
  • Aqueous Phase Synthesized CdSe Nanoparticles with Well-Defined Numbers of Constituent Atoms
    Yeon-Su Park, Andriy Dmytruk, Igor Dmitruk, Atsuo Kasuya, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Journal of Physical Chemistry C, 114, 44, 18834, 18840, Nov. 2010, [Peer-reviewed]
    English, Scientific journal
  • DNA separation by cholesterol-bearing pullulan nanogels
    Keisuke Kondo, Noritada Kaji, Sayaka Toita, Yukihiro Okamoto, Manabu Tokeshi, Kazunari Akiyoshi, Yoshinobu Baba
    Biomicrofluidics, 4, 3, 032210-1, 10, Sep. 2010, [Peer-reviewed]
    English, Scientific journal
  • Quantum dots labeling using octa-arginine peptides for imaging of adipose tissue-derived stem cells
    Hiroshi Yukawa, Yukimasa Kagami, Masaki Watanabe, Koichi Oishi, Yoshitaka Miyamoto, Yukihiro Okamoto, Manabu Tokeshi, Noritada Kaji, Hirofumi Noguchi, Kenji Ono, Makoto Sawada, Yoshinobu Baba, Nobuyuki Hamajima, Shuji Hayashi
    Biomaterials, 31, 14, 4094, 4103, May 2010, [Peer-reviewed]
    English, Scientific journal
  • A Probe Containing Two Base-discriminating Fluorescent (BDF) Nucleosides for SNP Typing
    Yasuko Yoshida, Kousuke Niwa, Kazunari Yamada, Manabu Tokeshi, Yoshinobu Baba, Yoshio Saito, Akimitsu Okamoto, Isao Saito
    Chemistry Letters, 39, 2, 116, 117, Feb. 2010, [Peer-reviewed]
    English, Scientific journal
  • Size-Selective Growth and Stabilization of Small CdSe Nanoparticles in Aqueous Solution
    Yeon-Su Park, Andriy Dmytruk, Igor Dmitruk, Atsuo Kasuya, Motohiro Takeda, Noriaki Ohuchi, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    ACS Nano, 4, 1, 121, 128, Jan. 2010, [Peer-reviewed]
    English, Scientific journal
  • Development of an Easy and High-Throughput Cell Assay System with a Culture Chip and an Assay Chip
    Kanako Sugiura, Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Yoshinobu Baba
    IEEJ Transactions on Sensors and Micromachines, 130, 10, 471, 475, Institute of Electrical Engineers of Japan (IEE Japan), 2010, [Peer-reviewed]
    Japanese, Scientific journal
  • Immuno-pillar chip: a new platform for rapid and easy-to-use immunoassay
    Mai Ikami, Ayako Kawakami, Masaya Kakuta, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Lab on a Chip, 10, 24, 3335, 3340, 2010, [Peer-reviewed]
    English, Scientific journal
  • Nanopillar, nanoball, and nanofibers for highly efficient analysis of biomolecules
    Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Yoshinobu Baba
    Chemical Society Reviews, 39, 3, 948, 948, Royal Society of Chemistry (RSC), 2010, [Peer-reviewed]
    English, Scientific journal
  • Exceeding 20 000-fold concentration of protein by the on-line isotachophoresis concentration in poly(methyl methacrylate) microchip
    Jun Wang, Yong Zhang, Molhamad Reza Mohamadi, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Electrophoresis, 30, 18, 3250, 3256, Sep. 2009, [Peer-reviewed]
    English, Scientific journal
  • Cell separation by the combination of microfluidics and optical trapping force on a microchip
    Masaya Murata, Yukihiro Okamoto, Yeon-Su Park, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical and Bioanalytical Chemistry, 394, 1, 277, 283, May 2009, [Peer-reviewed]
    English, Scientific journal
  • Microchip-based homogeneous immunoassay using fluorescence polarization spectroscopy.
    Tomoya Tachi, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Lab on a Chip, 9, 7, 966, 71, 07 Apr. 2009, [Peer-reviewed], [International Magazine]
    English, Scientific journal, We have realized fluorescence polarization immunoassay (FPIA) on a microchip in about 1 minute. FPIA is a homogeneous competitive immunoassay which is based on measuring fluorescence polarization after competitive binding of an analyte and a tracer to an antibody. We constructed a microfluidic FPIA system composed of a newly designed microchip, a laser, a CCD camera and an optical microscope with two specially installed polarizers-one fixed and one rotatable. Theophylline, a typical small drug molecule, was used as a model analyte. Theophylline and fluorescence-labeled theophylline were introduced through different inlets and combined in a 100 microm-wide microchannel where anti-theophylline antibody was added. To optimize the microchip design for FPIA, we investigated the diffusion time of theophylline and the mixing time of theophylline and antibody in this channel, which were 6 s and 36 s, respectively. We successfully carried out a quantitative analysis of theophylline in serum near the therapeutic range in 65 s. In FPIA, a larger tracer-antibody complex emits more polarized fluorescence than the tracer, and therefore, by increasing the antigen concentration in a sample, more polarization relaxation is observed since the tracer-antibody complex concentration is decreased and the tracer concentration is increased. Tracer binding to an antibody is directly measured by spectroscopic techniques without any separation process.This microchip-based FPIA is very simple and rapid, unlike microchip-based heterogeneous immunoassay, because it does not require several processes such as washing and reflowing and immobilizing of antibodies or antigens in the channel. In the future, microchip-based FPIA should find frequent use for point-of-care testing in the clinical field, where conventional FPIA has been used for laboratory tests.
  • Simultaneous Separation, Metering, and Dilution of Plasma from Human Whole Blood in a Microfluidic System
    Tomoya Tachi, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Chemistry, 81, 8, 3194, 3198, Apr. 2009, [Peer-reviewed]
    English, Scientific journal
  • Phase separation of gas-liquid and liquid-liquid microflows in microchips
    Arata Aota, Kazuma Mawatari, Susumu Takahashi, Teruki Matsumoto, Kazuteru Kanda, Ryo Anraku, Akihide Hibara, Manabu Tokeshi, Takehiko Kitamori
    Microchimica Acta, 164, 3-4, 249, 255, Mar. 2009, [Peer-reviewed]
    English, Scientific journal
  • Microchip-based homogeneous immunoassay using a cloned enzyme donor.
    Tomoya Tachi, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Sciences, 25, 2, 149, 51, Feb. 2009, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal, We have realized a cloned enzyme donor immunoassay (CEDIA) on a microchip in 96 s. CEDIA is a homogeneous immunoassay, based on the bacterial enzyme beta-galactosidase, which was genetically engineered into two inactive fragments: an enzyme donor and an enzyme acceptor. A model analyte was theophylline, and the detectable concentration range was from 0 to 40 microg mL(-1). Our CEDIA using a microfluidic device was very simple and rapid, unlike microchip-based heterogeneous immunoassays and CEDIA on a well-type microchip.
  • Luminescence of Cup-Stacked Carbon Nanotubes and Its Application to Microchip Electrophoresis
    Yousuke Inoue, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    BUNSEKI KAGAKU, 58, 6, 517, 521, Japan Society for Analytical Chemistry, 2009, [Peer-reviewed]
    Japanese, Scientific journal
  • A micro-ELISA system for the rapid and sensitive measurement of total and specific immunoglobulin E and clinical application to allergy diagnosis
    Toshinori Ohashi, Kazuma Mawatari, Kae Sato, Manabu Tokeshi, Takehiko Kitamori
    Lab on a Chip, 9, 7, 991, 995, 2009, [Peer-reviewed]
    English, Scientific journal
  • Quantum Dots for Labeling Adipose Tissue-Derived Stem Cells
    Hiroshi Yukawa, Shogo Mizufune, Chiharu Mamori, Yukimasa Kagami, Koichi Oishi, Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Hirofumi Noguchi, Yoshinobu Baba, Michinari Hamaguchi, Nobuyuki Hamajima, Shuji Hayashi
    Cell Transplantation, 18, 5-6, 591, 599, 2009
    English, Scientific journal
  • Nanotechnologies in the biosciences
    Manabu Tokeshi, Yoshinobu Baba
    Analytical and Bioanalytical Chemistry, 391, 8, 2693, 2694, Aug. 2008, [Peer-reviewed]
    Scientific journal
  • On-chip fabrication of mutifunctional envelope-type nanodevices for gene delivery
    Hiroshi Kuramoto, Yeon-Su Park, Noritada Kaji, Manabu Tokeshi, Kentaro Kogure, Yasuo Shinohara, Hideyoshi Harashima, Yoshinobu Baba
    Analytical and Bioanalytical Chemistry, 391, 8, 2729, 2733, Aug. 2008
    English, Scientific journal
  • A viscosity-tunable polymer for DNA separation by microchip electrophoresis
    Daisuke Kuroda, Yong Zhang, Jun Wang, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical and Bioanalytical Chemistry, 391, 7, 2543, 2549, Aug. 2008
    English, Scientific journal
  • Flowing thermal lens micro-flow velocimeter
    Yoshikuni Kikutani, Kazuma Mawatari, Kenji Katayama, Manabu Tokeshi, Takashi Fukuzawa, Mitsuo Kitaok, Takehiko Kitamori
    Sensors and Actuators B-Chemical, 133, 1, 91, 96, Jul. 2008, [Peer-reviewed]
    English, Scientific journal
  • Highly sensitive double-fluorescent dye staining method on microchip electrophoresis for analysis of milk proteins
    Hiroki Okada, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Electrophoresis, 29, 12, 2533, 2538, Jun. 2008, [Peer-reviewed]
    English, Scientific journal
  • Microchip analysis of plant glucosinolates
    Maged Fouad, Mohammad Jabasini, Noritada Kaji, Kazuyoshi Terasaka, Manabu Tokeshi, Hajime Mizukami, Yoshinobu Baba
    Electrophoresis, 29, 11, 2280, 2287, Jun. 2008, [Peer-reviewed]
    English, Scientific journal
  • Numerical analysis of thermal lens effect for sensitive detection on microchips
    Ryo Anraku, Kazuma Mawatari, Manabu Tokeshi, Masatoshi Nara, Takahiro Asai, Akihiko Hattori, Takehiko Kitamori
    Electrophoresis, 29, 9, 1895, 1901, May 2008, [Peer-reviewed]
    English, Scientific journal
  • Accurate quantitation of salivary and pancreatic amylase activities in human plasma by microchip electrophoretic separation of the substrates and hydrolysates coupled with immunoinhibition
    Eiki Maeda, Masatoshi Kataoka, Shouki Yatsushiro, Kazuaki Kajimoto, Mami Hino, Noritada Kaji, Manabu Tokeshi, Mika Bando, Jun-Ichi Kido, Mitsuru Ishilkawa, Yasuo Shinohara, Yoshinobu Baba
    Electrophoresis, 29, 9, 1902, 1909, May 2008
    English, Scientific journal
  • Rinse and evaporation coating of poly(methyl methacrylate) microchip for separation of sodium dodecyl sulfate-protein complex
    Hiroki Okada, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Journal of Chromatography A, 1192, 2, 289, 293, May 2008
    English, Scientific journal
  • Rolling circle amplification and circle-to-circle amplification of a specific gene integrated with electrophoretic analysis on a single chip
    Laili Mahmoudian, Noritada Kaji, Manabu Tokeshi, Mats Nilsson, Yoshinobu Baba
    Analytical Chemistry, 80, 7, 2483, 2490, Apr. 2008
    English, Scientific journal
  • Microchip Electrophoresis for Specific Gene Detection of the Pathogenic Bacteria V. cholerae by Circle-to-Circle Amplification
    Laili Mahmoudian, Jonas Melin, Mohamad Reza Mohamadi, Keiko Yamada, Michio Ohta, Noritada Kaji, Manabu Tokeshi, Mats Nilsson, Yoshinobu Baba
    Analytical Sciences, 24, 3, 327, 332, 10 Mar. 2008, [Peer-reviewed]
    English, Scientific journal
  • Poly(methylmethacrylate) microchip electrophoresis of proteins using linear-poly(acrylamide) solutions as separation matrix
    Hiroki Okada, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Sciences, 24, 3, 321, 325, Mar. 2008
    English, Scientific journal
  • Quantitative determination of amino acids in functional foods by microchip electrophoresis
    Hiroko Ueno, Jun Wang, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Journal of Separation Science, 31, 5, 898, 903, Mar. 2008
    English, Scientific journal
  • Nuclease tolerant FRET probe based on DNA-quantum dot conjugation
    Daisuke Onoshima, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Sciences, 24, 2, 181, 183, Feb. 2008
    English, Scientific journal
  • Dynamic cross-linking effect of Mg2+ to enhance sieving properties of low-viscosity poly(vinylpyrrolidone) solutions for microchip electrophoresis of proteins
    Mohamad Reza Mohamadi, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Chemistry, 80, 1, 312, 316, Jan. 2008
    English, Scientific journal
  • Channel wall coating on a poly-(methyl methacrylate) CE microchip by thermal immobilization of a cellulose derivative for size-based protein separation.
    Hiroki Okada, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Electrophoresis, 28, 24, 4582, 9, Dec. 2007, [Peer-reviewed], [International Magazine]
    English, Scientific journal, We demonstrate channel wall coating using a cellulose derivative on a poly-(methyl methacrylate) (PMMA) CE microchip to eliminate EOF disturbing protein separation. The channel walls were modified by preconditioning with a solution containing the cellulose derivative and then thermally evaporating the solution to produce hydrophilic channel walls which prevent adsorption of analytes via a hydrophobic interaction. When the PMMA substrate was coated with the cellulose derivative hydroxypropylmethylcellulose (HPMC) 90SH, the water contact angle on the coated substrate was decreased (up to 15 degrees ) and EOF was significantly suppressed (up to 4.0 x 10(-6) cm2.V(-1)s(-1)). Three proteins (20.5, 68.0, and 114.6 kDa) were successfully separated on the 0.15% HPMC 90SH-coated channel walls with good reproducibility of migration time (RSD <1.75%) and high efficiency (theoretical plate number per meter: 2.62 x 10(5)).
  • Dynamic modification of poly(methyl methacrylate) chips using poly(vinyl alcohol) for glycosaminoglycan disaccharide isomer separation.
    Yong Zhang, Guichen Ping, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Electrophoresis, 28, 18, 3308, 14, Sep. 2007, [Peer-reviewed], [International Magazine]
    English, Scientific journal, We describe a microchip electrophoresis (MCE) method for the assay of unsaturated disaccharides of chondroitin sulfates, dermatan sulfates, and hyaluronic acid (HA). Poly(vinyl alcohol) (PVA) could be irreversibly adsorbed onto poly(methyl methacrylate) (PMMA) substrates and this approach was applicable for dynamic coating. The characteristics of the PMMA surface with PVA coating were evaluated in terms of the wettability, EOF, and adsorption of 2-aminoacridone (AMAC)-labeled disaccharide. The water contact angle decreased from 73 degrees on a pristine PMMA surface to 37.5 degrees on a PVA-coated surface, indicating that the PVA coating increased hydrophilicity. EOF was reduced approximately twofold and was relatively stable. Scanning electron microscopy and fluorescence microscopy images showed that adsorption of AMAC-labeled disaccharides was dramatically suppressed. Using the PVA coating, baseline separation of two pairs of glycosaminoglycan (GAG) disaccharide isomers, DeltaDi-diS(B)/DeltaDi-diS(D) and DeltaDi-0S/DeltaDi-HA, was achieved in Tris-borate buffer within 130 s by MCE.
  • Nanobiotechnology: quantum dots in bioimaging
    Yong Zhang, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Expert Review of Proteomics, 4, 4, 565, 572, Informa UK Limited, Aug. 2007, [Peer-reviewed], [Invited]
    English, Scientific journal
  • Online preconcentration by transient isotachophoresis in linear polymer on a poly(methyl methacrylate) microchip for separation of human serum albumin immunoassay mixtures.
    Mohamad Reza Mohamadi, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Chemistry, 79, 10, 3667, 72, 15 May 2007, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Online preconcentration of human serum albumin (HSA) and its immunocomplex with a monoclonal antibody by on-chip transient isotachophoresis is reported. An 800-fold signal enhancement was achieved following the preconcentration on standard cross-channel microchips made of poly (methyl methacrylate). Sample injection, preconcentration, and separation were done continuously and controlled solely by a sequential voltage switching program. The preconcentration was followed by on-chip nondenaturing gel electrophoresis in methylcellulose solution. The method was applied to microchip electrophoresis immunoassay of HSA. Baseline separation of HSA and its immunocomplex was achieved in 25 s in the first 1 cm of the microchannel. In a direct immunoassay, the minimum detectable concentration of fluorescent labeled HSA by laser-induced fluorescence detection was 7.5 pM.
  • Evaluation of amplified cRNA targets for oligonucleotide microarrays.
    Akihiro Sawada, Shogo Mizufune, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical and Bioanalytical Chemistry, 387, 8, 2645, 54, Apr. 2007, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Due to their hybridization specificity and capacity for systematic gene discovery, oligonucleotide-based microarray platforms offer numerous advantages over the cDNA microarrays currently widely used for comprehensive analysis of gene expression. Although fluorescently labeled amplified cRNA generated by T7 transcription is generally used in oligonucleotide microarrays, the feasibility of this combination (and that of cDNA microarrays) is yet to be studied systematically. In this paper, we performed a comparative study using a direct labeling method and T7 amplification to evaluate amplified cRNA targets for oligonucleotide microarrays. The efficiency of incorporation of Cy3- and Cy5-CTP into the target preparations, the reproducibility and the number of genes detected were investigated for each labeling approach and compared. The 12 genes that showed different expression profiles in the two labeling methods were evaluated by quantitative real-time PCR. In the 60-mer oligonucleotide microarray, amplified cRNA targets prepared by the T7 amplification method showed higher reproducibility and reliability than targets prepared by the direct labeling method in a comparative analysis of gene expression. This result also suggests the importance of fragmenting cRNA down to lengths of 50-200 bases before the hybridization process.
  • Enhanced electrophoretic resolution of monosulfate glycosaminoglycan disaccharide isomers on poly(methyl methacrylate) chips.
    Yong Zhang, Guichen Ping, Bingmei Zhu, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Electrophoresis, 28, 3, 414, 21, Feb. 2007, [Peer-reviewed], [International Magazine]
    English, Scientific journal, To improve the separation of monosulfate glycosaminoglycan disaccharide isomers by microchip electrophoresis, we found that addition of 1,4-dioxane (DO) dramatically improved analyte resolution, probably due to solvation effects. Methylcellulose (MC) was tested for the ability to suppress EOF and analyte adsorption to the chip. To improve analyte resolution, buffer pH, beta-CD, and DO were systematically investigated. Fast separation was achieved by increasing the electric field strength, and field-amplified sample stacking occurred with increasing buffer concentrations. Therefore, based on our findings, we describe an efficient method for the separation of monosulfate and trisulfate unsaturated disaccharides (DeltaDi-UA2S, DeltaDi-4S, DeltaDi-6S, and DeltaDi-triS) derivatized with 2-aminoacridone hydrochloride. A mixture of monosulfate disaccharide isomers (DeltaDi-UA2S, DeltaDi-4S, and DeltaDi-6S) was baseline-separated within 75 s on a poly(methyl methacrylate) chip using a mixed buffer (DO/running buffer 57:43 v:v), 0.5% MC, pH 6.81, with an E(sep) of 558 V/cm. The theoretical plate was in the range of 5 x 10(5) to 1 x 10(6) m-1.
  • Highly Sensitive Detection of Non-Labeled Peptides Using UV Excitation Thermal Lens Microscope/Liquid Chromatography
    Shinichiro HIKI, Manabu TOKESHI, Masaya KAKUTA, Kazuma MAWATARI, Yoshikuni KIKUTANI, Kiichi SATO, Akihide HIBARA, Kiyohito SHIMURA, Naoyuki UCHIDA, Takehiko KITAMORI
    BUNSEKI KAGAKU, 56, 1, 1, 7, 2007, [Peer-reviewed]
    Japanese, Scientific journal
  • Quantum dots for single bio-molecule imaging.
    Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Analytical Sciences, 23, 1, 21, 4, Springer Science and Business Media LLC, Jan. 2007, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal, The emerging nanomaterial, quantum dots or QDs, offers numerous potential applications in the biological area. As cell labeling probes, QDs become now an alternative of existing organic fluorescent dyes and fluorescent proteins. In this short review, we cover typical and successful applications of QDs as fluorescent probes in cell labeling and genomic diagnosis. As a future important application, biomolecular detection at a single molecule level utilizing QDs is also discussed.
  • Development of the microchip-based repeatable immunoassay system for clinical diagnosis
    M. Kakuta, H. Takahashi, S. Kazuno, K. Murayama, T. Ueno, M. Tokeshi
    Measurement Science and Technology, 17, 12, 3189, 3194, Institute of Physics Publishing, 01 Dec. 2006, [Peer-reviewed]
    English, Scientific journal
  • Pressure-driven flow control system for nanofluidic chemical process
    Eiichiro Tamaki, Akihide Hibara, Haeng-Boo Kim, Manabu Tokeshi, Takehiko Kitamori
    Journal of Chromatography A, 1137, 2, 256, 262, Dec. 2006, [Peer-reviewed]
    English, Scientific journal
  • Study of water properties in nanospace.
    Noritada Kaji, Ryo Ogawa, Akio Oki, Yasuhiro Horiike, Manabu Tokeshi, Yoshinobu Baba
    Analytical and Bioanalytical Chemistry, 386, 3, 759, 64, Oct. 2006, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Here we report an anomalous behavior of water, especially its viscosity and hydrodynamic flow, in a nanometer-confined space. As a typical model of a nanometer-confined space, the nanopillar chip, which was developed for DNA size-based separation was used, and single-particle tracking (SPT) technique was applied to investigate water viscosity and hydrodynamic flow in the nanopillar chip. The diffusion coefficients of nanospheres were almost one-third of the theoretical value derived from the Stokes-Einstein equation. This result gave indirect proof that water viscosity in a nanometer-confined space is higher than in a bulk solution. In order to improve resolution and throughput of the nanopillar chip for DNA separation, these potential factors affecting performance should be seriously considered.
  • Microchip-based liquid–liquid extraction for gas-chromatography analysis of amphetamine-type stimulants in urine
    Hajime Miyaguchi, Manabu Tokeshi, Yoshikuni Kikutani, Akihide Hibara, Hiroyuki Inoue, Takehiko Kitamori
    Journal of Chromatography A, 1129, 1, 105, 110, Sep. 2006, [Peer-reviewed]
    English, Scientific journal
  • Electrophoretic behavior of plasmid DNA in the presence of various intercalating dyes.
    Fuquan Dang, Wenhao Li, Lihua Zhang, Mohammad Jabasini, Tatsuhiro Ishida, Hiroshi Kiwada, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Journal of Chromatography. A, 1118, 2, 218, 25, 23 Jun. 2006, [Peer-reviewed], [International Magazine]
    English, Scientific journal, In the present study, the electrophoretic behavior of linear, supercoiled and nicked circular plasmid DNA in the presence of various intercalating dyes was characterized using pGL3 plasmid DNA as a model. The enzymatic digestion of pGL3 plasmid DNA with HindIIIwas monitored by capillary electrophoresis coupled with laser-induced fluorescence detection (CE-LIF). Nicked circular plasmid DNA was found to be relatively sensitive to enzymes, and was almost digested into the linear conformer after 10-min incubation, indicating that nicked circular plasmid DNA has little chance of targeting and entering the cell nucleus. Partly digested plasmid DNA containing only linear and supercoiled conformers can be used as a standard to confirm the migration order of plasmid DNA. In methylcellulose (MC) solution with YO-PRO-1 or YOYO-1, linear plasmid DNA eluted first, followed by supercoiled and nicked plasmid DNA, and nicked plasmid DNA eluted as a broad peak. With SYBR Green 1, nicked plasmid DNA eluted first as three sharp peaks, followed by linear and supercoiled plasmid DNA. The nuclear plasmid DNA from two transfected cell lines was successfully analyzed using the present procedure. Similar results were obtained with an analysis time of seconds using microchip electrophoresis with laser-induced fluorescence detection (mu-CE-LIF). To our knowledge, these results represent the first reported analysis of nuclear plasmid DNA from transfection cells by CE-LIF or mu-CE-LIF without pre-preparation, suggesting that the present procedure is a promising alternative method for evaluating transfection efficiency of DNA delivery systems.
  • Quantitative detection and fixation of single and multiple gold nanoparticles on a microfluidic chip by thermal lens microscope
    Kazuma Mawatari, Manabu Tokeshi, Takehiko Kitamori
    Analytical Sciences, 22, 5, 781, 784, May 2006, [Peer-reviewed]
    English, Scientific journal
  • Circular dichroism thermal lens microscope for sensitive chiral analysis on microchip
    Masayo Yamauchi, Kazuma Mawatari, Akihide Hibara, Manabu Tokeshi, Takehiko Kitamori
    Analytical Chemistry, 78, 8, 2646, 2650, 15 Apr. 2006, [Peer-reviewed]
    English, Scientific journal
  • Monitoring of intercellular messengers released from neuron networks cultured in a microchip
    Kiichi Sato, Akiko Egami, Tamao Odake, Manabu Tokeshi, Makoto Aihara, Takehiko Kitamori
    Journal of Chromatography A, 1111, 2, 228, 232, 14 Apr. 2006, [Peer-reviewed]
    English, International conference proceedings
  • Liquid Filling Method for Nanofluidic Channels Utilizing the High Solubility of CO2
    Eiichiro Tamaki, Akihide Hibara, Haeng-Boo Kim, Manabu Tokeshi, Takeshi Ooi, Masayuki Nakao, Takehiko Kitamori
    Analytical Sciences, 22, 4, 529, 532, 14 Apr. 2006, [Peer-reviewed]
    English, Scientific journal
  • Total reflection X-ray fluorescence analysis with chemical microchip
    Kouichi Tsuji, Yousuke Hanaoka, Akihide Hibara, Manabu Tokeshi, Takehiko Kitamori
    Spectrochimica Acta - Part B Atomic Spectroscopy, 61, 4, 389, 392, Apr. 2006
    English, Scientific journal
  • Low viscous separation media for genomics and proteomics analysis on microchip electrophoresis system.
    Mohammad Jabasini, Yuji Murakami, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Biological and Pharmaceutical Bulletin, 29, 4, 595, 604, Pharmaceutical Society of Japan, Apr. 2006, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal, Microchip electrophoresis has widely grown during the past few years, and it has showed a significant result as a strong separation tool for genomic as well as proteomic researches. To enhance and expand the role of microchip electrophoresis, several studies have been proposed especially for the low viscous separation media, which is an important factor for the success of microchip with its narrow separation channels. In this paper we show an overview for the done researches in the field of low viscous media developed for the use in microchip electrophoresis. For genomic separation studies polyhydroxy additives have been used enhance the separation of DNA at low polymer concentration of HPMC (Hydroxypropylmethyl cellulose) which could keep the viscosity low. Mixtures of poly(ethylene oxide) as well as Hydroxyporpyl cellulose have been successfully introduced for chip separation. Furthermore high molecular mass polyacrylamides at low concentrations have been studied for DNA separation. A mixture of polymer nanoparticle with conventional polymers could show a better resolution for DNA at low concentration of the polymer. For the proteomic field isoelectric focusing on chip has been well overviewed since it is the most viscous separation media which is well used for the protein separation. The different types of isoelectric focusing such as the ampholyte-free type, the thermal type as well as the ampholyte-depended type have been introduced in this paper. Isoelectric focusing on chip with its combination with sodium dodecyl sulfate (SDS) page or free solution could give a better separation. Several application for this low viscous separation medias for either genomic or proteomic could clearly show the importance of this field.
  • Rapid analysis of oligosaccharides derived from glycoproteins by microchip electrophoresis.
    Fuquan Dang, Kazuaki Kakehi, Kazuki Nakajima, Yasuo Shinohara, Mitsuru Ishikawa, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Journal of Chromatography. A, 1109, 2, 138, 43, 24 Mar. 2006, [Peer-reviewed], [International Magazine]
    English, Scientific journal, A novel method for fast profiling of complex oligosaccharides released from glycoproteins based on microchip electrophoresis (mu-CE) is presented here. The characterization of separation conditions, i.e., the composition, concentration and pH of running buffer as well as the applied voltage, has been performed using maltose (G2), cellobiose ( G2'), maltriose (G3) and panose (G3') as oligosaccharide isomer models. In mu-CE, much better separation of oligosaccharide isomers and oligosaccharide ladder was obtained in phosphate buffer than in borate buffer over a wide pH range. Under optimal conditions, high-performance separation of the N-linked complex oligosaccharides released from ribonuclease B, fetuin, alpha1-acid glycoprotein (AGP) and IgG was achieved using polymethylmethacrylate (PMMA) microchips with an effective separation channel of 30 mm. These results represent the first reported analysis of the N-linked oligosaccharides derived from glycoproteins by mu-CE, indicating that the present mu-CE-based method is a promising alternative for characterization of the N-linked oligosaccharides in glycoproteins.
  • Development of the innovative nuclide separation system for high-level radioactive waste using microchannel chip—extraction behavior of metal ions from aqueous phase to organic phase in microchannel
    Hiroyasu Hotokezaka, Manabu Tokeshi, Masayuki Harada, Takehiko Kitamori, Yasuhisa Ikeda
    Progress in Nuclear Energy, 48, 2, 187, 187, Elsevier BV, Mar. 2006, [Peer-reviewed]
    English, Scientific journal
  • Nanotechnology for genomics & proteomics
    Mohamad Reza Mohamadi, Laili Mahmoudian, Noritada Kaji, Manabu Tokeshi, Hiroshi Chuman, Yoshinobu Baba
    Nano Today, 1, 1, 38, 45, Elsevier BV, Feb. 2006, [Peer-reviewed], [Invited]
    English, Scientific journal
  • Miniaturized thermal lens and fluorescence detection system for microchemical chips
    Masayo Yamauchi, Manabu Tokeshi, Jun Yamaguchi, Takashi Fukuzawa, Akihiko Hattori, Akihide Hibara, Takehiko Kitamori
    Journal of Chromatography A, 1106, 1-2, 89, 93, Feb. 2006, [Peer-reviewed]
    English, Scientific journal
  • Radiation Degradation of Microchemical Chips and Capillary Tubes by Gamma-Ray Irradiation
    Hidematsu IKEDA, Manabu TOKESHI, Hiroyasu HOTOKEZAKA, Yasuhisa IKEDA, Takehiko KITAMORI
    Transactions of the Atomic Energy Society of Japan, 5, 3, 209, 220, Atomic Energy Society of Japan, 2006, [Peer-reviewed]
    Japanese, Scientific journal
  • “UV-excitation thermal lens microscope for non-labeled and ultrasensitive detection of non-fluorescent molecules
    S. Hiki, K.Mawatari, A.Hibara, M.Tokeshi, T.Kitamori
    Analytical Chemistry, 8, 78, 2859, 2863, 2006, [Peer-reviewed]
    English, Scientific journal
  • Rapid Multiplexing and Simultaneous Detection of Human Spermatogenetic Failure with a 12 Lane Microchip Electrophoresis System
    Mohammad Jabasini, Ashraf Abdulazim Ewis, Maged Fouad, Fuquan Dang, Guichen Ping, Toshikatsu Shinka, Yutaka Nakahori, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Biological and Pharmaceutical Bulletin, 29, 7, 1487, 1489, Pharmaceutical Society of Japan, 2006, [Peer-reviewed]
    English, Scientific journal
  • Continuous‐Flow Chemical Processing in Three‐Dimensional Microchannel Network for On‐Chip Integration of Multiple Reactions in a Combinatorial Mode
    Yoshikuni Kikutani, Masaharu Ueno, Hideaki Hisamoto, Manabu Tokeshi, Takehiko Kitamori
    QSAR & Combinatorial Science, 24, 6, 742, 757, Wiley, 16 Aug. 2005, [Peer-reviewed], [Invited]
    English, Scientific journal, Abstract

    Chemical syntheses using microchemical chips have been intensively investigated in recent years, but they have still not fully reached the stage of practical use. Combinatorial synthesis has been expected to be one of their useful applications. Benefits of using microchips, such as reduction in quantity of reagents and wastes, are thought to be suited for combinatorial syntheses, where numerous variations of products have to be synthesized each in small amounts. There are two modes of combinatorial syntheses using microchemical chips. One is sequential synthesis, in which reactant solutions are introduced sequentially in various combinations to a reaction microchannel. The other is parallel synthesis, where the number of reaction channels is the same as the number of final products, and starting materials are distributed to all the reaction channels in different combinations. Sequential synthesis has been considered as the more favorable way, because, especially when libraries of starting materials are large, numerous microchannels and complicated pipings for distribution of reagents to the channels are required for the parallel mode. Therefore, research on parallel microcombinatorial syntheses has been done only rarely, whereas there have been many reports of sequential microcombinatorial syntheses. Against this trend, our research group has taken an alternative path and tried to integrate both parallel reaction microchannels onto a glass microchip and channels for distributing reactant solutions to each reaction channel in a combinatorial mode. Microchips fabricated by laminating multiple layers of glass substrates have been used to construct three‐dimensional microchannel networks necessary for mixing reagent flows in different combinations. We utilized low Reynolds number multi‐phase laminar flow and developed micro‐unit operations (MUOs). By combining MUOs in the multi‐phase continuous laminar flows, microchemical systems were constructed. We called this micro‐integration methodology “continuous‐flow chemical processing (CFCP)”, and by using it, a sequence of various operations in chemical syntheses could be integrated on a microchemical chip. Not just simple mixing of two reagents, which was most commonly done in microreactors, but also multi‐step processes including other chemical operations, such as extraction and separation, could be carried out via CFCP. In the first part of this short review article, we explain CFCP with an example. Then, a microchemical chip with a three‐dimensional microchannel network for a parallel reaction system is introduced. Finally, we present a case in which CFCP was realized in a three‐dimensional microchannel network.
  • System for high-level radioactive waste using microchannel chip - Extraction behavior of metal ions from aqueous phase to organic phase in microchannel
    Hiroyasu Hotokezaka, Manabu Tokeshi, Masayuki Harada, Takehiko Kitamori, Yasuhisa Ikeda
    Progress in Nuclear Energy, 47, 1-4, 439, 447, Jul. 2005, [Peer-reviewed]
    English, International conference proceedings
  • Effect of korteweg stress in miscible liquid two-layer flow in a microfluidic device
    Y. Sugii, K. Okamoto, A. Hibara, M. Tokeshi, T. Kitamori
    Journal of Visualization, 8, 2, 117, 124, Jun. 2005, [Peer-reviewed]
    Scientific journal
  • Surface modification method of microchannels for gas-liquid two-phase flow in microchips
    Akihide Hibara, Shinobu Iwayama, Shinya Matsuoka, Masaharu Ueno, Yoshikuni Kikutani, Manabu Tokeshi, Takehiko Kitamori
    Analytical Chemistry, 77, 3, 943, 947, 01 Feb. 2005, [Peer-reviewed]
    English, Scientific journal
  • Optimization of an Interface Chip for Coupling Capillary Electrophoresis with Thermal Lens Microscopic Detection
    Kenji Uchiyama, Manabu Tokeshi, Yoshikuni Kikutani, Akihiko Hattori, Takehiko Kitamori
    Analytical Sciences, 21, 1, 49, 52, 25 Jan. 2005, [Peer-reviewed]
    English, Scientific journal
  • Continuous flow chemical processing on a microchip using microunit operations and a multiphase flow network
    Manabu Tokeshi, Takehiko Kitamori
    Progress in Nuclear Energy, 47, 1-4, 434, 438, Jan. 2005, [Peer-reviewed]
    English, Scientific journal
  • Tunable thermal lens spectrometry utilizing microchannel-assisted thermal lens spectrometry
    Eiichiro Tamaki, Akihide Hibara, Manabu Tokeshi, Takehiko Kitamori
    Lab on a Chip, 5, 2, 129, 129, 2005, [Peer-reviewed]
    English, Scientific journal
  • Development of a Microchip-Based Bioassay System Using Cultured Cells               
    Makiko Goto, Kiichi Sato, Atsushi Murakami, Manabu Tokeshi, Takehiko Kitamori
    Analytical Chemistry, 77, 2125, 2131, 2005
  • Thermal Lens Micro Optical Systems
    Manabu Tokeshi, Jun Yamaguchi, Akihiko Hattori, Takehiko Kitamori
    Analytical Chemistry, 77, 2, 626, 630, 08 Dec. 2004, [Peer-reviewed]
    English, Scientific journal
  • Rapid proton diffusion in microfluidic devices by means of micro-LIF technique
    K. Shinohara, Y. Sugii, A. Hibara, M. Tokeshi, T. Kitamori, K. Okamoto
    Experiments in Fluids, 38, 1, 117, 122, 30 Nov. 2004, [Peer-reviewed]
    English, Scientific journal
  • High-speed micro-PIV measurements of transient flow in microfluidic devices
    Kyosuke Shinohara, Yasuhiko Sugii, Arata Aota, Akihide Hibara, Manabu Tokeshi, Takehiko Kitamori, Koji Okamoto
    Measurement Science and Technology, 15, 10, 1965, 1970, 21 Aug. 2004, [Peer-reviewed]
    English, Scientific journal
  • Measurement of pH field of chemically reacting flow in microfluidic devices by laser-induced fluorescence
    Kyosuke Shinohara, Yasuhiko Sugii, Koji Okamoto, Haruki Madarame, Akihide Hibara, Manabu Tokeshi, Takehiko Kitamori
    Measurement Science and Technology, 15, 5, 955, 960, 21 Apr. 2004, [Peer-reviewed]
    English, Scientific journal
  • Peer Reviewed: Thermal Lens Microscopy and Microchip Chemistry
    Takehita Kitamori, Manabu Tokeshi, Akihide Hibara, Kiichi Sato
    Analytical Chemistry, 76, 3, 52 A, 60 A, 01 Feb. 2004, [Peer-reviewed]
    English, Scientific journal
  • Microchip-based enzyme-linked immunosorbent assay (microELISA) system with thermal lens detection
    Kiichi Sato, Maho Yamanaka, Tomokazu Hagino, Manabu Tokeshi, Hiroko Kimura, Takehiko Kitamori
    Lab on a Chip, 4, 6, 570, 575, Royal Society of Chemistry, 2004, [Peer-reviewed]
    English, Scientific journal
  • Spectroscopic Analysis of Liquid/Liquid Interfaces in Multiphase Microflows
    Akihide Hibara, Masaki Nonaka, Manabu Tokeshi, Takehiko Kitamori
    Journal of the American Chemical Society, 125, 49, 14954, 14955, 15 Nov. 2003, [Peer-reviewed]
    English, Scientific journal
  • Chemical processing on microchips for analysis, synthesis, and bioassay
    Manabu Tokeshi, Yoshikuni Kikutani, Akihide Hibara, Kiichi Sato, Hideaki Hisamoto, Takehiko Kitamori
    ELECTROPHORESIS, 24, 21, 3583, 3594, Wiley, 06 Nov. 2003, [Peer-reviewed], [Invited]
    English, Scientific journal, Abstract

    This review describes our recent research on miniaturization of chemical systems. We have developed a miniaturization methodology based on pressure‐driven multiphase laminar flow and a highly sensitive detection tool, the thermal lens microscope. Some representative applications of the methodology in the fields of analysis, synthesis, and bioassay are described.
  • Optimisation of thermal lens microscopic measurements in a microchip
    Mikhail A. Proskurnin, Maksim N. Slyadnev, Manabu Tokeshi, Takehiko Kitamori
    Analytica Chimica Acta, 480, 1, 79, 95, Elsevier, 17 Mar. 2003, [Peer-reviewed]
    English, Scientific journal
  • Microchip-based chemical and biochemical analysis systems
    Kiichi Sato, Akihide Hibara, Manabu Tokeshi, Hideaki Hisamoto, Takehiko Kitamori
    Advanced Drug Delivery Reviews, 55, 3, 379, 391, Elsevier BV, Feb. 2003, [Peer-reviewed], [Invited]
    English, Scientific journal
  • Microchannel-assisted thermal-lens spectrometry for microchip analysis
    Eiichiro Tamaki, Akihide Hibara, Manabu Tokeshi, Takehiko Kitamori
    Journal of Chromatography A, 987, 1-2, 197, 204, Feb. 2003, [Peer-reviewed]
    English, Scientific journal
  • Integration of Chemical and Biochemical Analysis Systems into a Glass Microchip
    Kiichi Sato, Akihide Hibara, Manabu Tokeshi, Hideaki Hisamoto, Takehiko Kitamori
    Analytical Sciences, 19, 1, 15, 22, Springer Science and Business Media LLC, 11 Jan. 2003, [Peer-reviewed], [Invited]
    English, Scientific journal
  • An interface chip connection between capillary electrophoresis and thermal lens microscope
    Kenji Uchiyama, Akihide Hibara, Kiichi Sato, Hideaki Hisamoto, Manabu Tokeshi, Takehiko Kitamori
    Electrophoresis, 24, 1-2, 179, 184, 10 Jan. 2003, [Peer-reviewed]
    English, Scientific journal
  • Fundamental Study on the Segmented Flow Injection - Multiphase Flow Formation Towards Microchip-Based Multi-Ion Sensing
    Hideaki Hisamoto, Takayuki Horiuchi, Akihide Hibara, Manabu Tokeshi, Takehiko Kitamori
    IEEJ Transactions on Sensors and Micromachines, 123, 4, 124, 127, Institute of Electrical Engineers of Japan (IEE Japan), 2003, [Peer-reviewed]
    Japanese, Scientific journal
  • Development of a desktop-sized thermal lens microscope
    Shinichiro HIKI, Manabu TOKESHI, Akihide HIBARA, Takehiko KITAMORI
    BUNSEKI KAGAKU, 52, 8, 569, 574, 2003, [Peer-reviewed]
    Japanese, Scientific journal
  • Chemicofunctional Membrane for Integrated Chemical Processes on a Microchip
    Hideaki Hisamoto, Yuki Shimizu, Kenji Uchiyama, Manabu Tokeshi, Yoshikuni Kikutani, Akihide Hibara, Takehiko Kitamori
    Analytical Chemistry, 75, 2, 350, 354, 13 Dec. 2002, [Peer-reviewed]
    English, Scientific journal
  • Integrated chemical systems on microchips for analysis and assay. Potential future, mobile high-performance detection system for chemical weapons
    Yoshikuni Kikutani, Manabu Tokeshi, Kiichi Sato, Takehiko Kitamori
    Pure and Applied Chemistry, 74, 12, 2299, 2309, Walter de Gruyter GmbH, 01 Dec. 2002, [Peer-reviewed]
    English, International conference proceedings
  • Nanochannels on a Fused-Silica Microchip and Liquid Properties Investigation by Time-Resolved Fluorescence Measurements
    Akihide Hibara, Takumi Saito, Haeng-Boo Kim, Manabu Tokeshi, Takeshi Ooi, Masayuki Nakao, Takehiko Kitamori
    Analytical Chemistry, 74, 24, 6170, 6176, 08 Nov. 2002, [Peer-reviewed]
    English, Scientific journal
  • Glass microchip with three-dimensional microchannel network for 2 × 2 parallel synthesis
    Yoshikuni Kikutani, Takayuki Horiuchi, Kenji Uchiyama, Hideaki Hisamoto, Manabu Tokeshi, Takehiko Kitamori
    Lab on a Chip, 2, 4, 188, 192, Royal Society of Chemistry, 01 Nov. 2002, [Peer-reviewed]
    English, Scientific journal
  • Microchip-based immunoassay system with branching multichannels for simultaneous determination of interferon-γ
    Kiichi Sato, Maho Yamanaka, Hiroko Takahashi, Manabu Tokeshi, Hiroko Kimura, Takehiko Kitamori
    Electrophoresis, 23, 5, 734, 739, Mar. 2002, [Peer-reviewed]
    English, Scientific journal
  • Single-Cell Analysis by a Scanning Thermal Lens Microscope with a Microchip:  Direct Monitoring of Cytochrome c Distribution during Apoptosis Process
    Eiichiro Tamaki, Kiichi Sato, Manabu Tokeshi, Kae Sato, Makoto Aihara, Takehiko Kitamori
    Analytical Chemistry, 74, 7, 1560, 1564, 21 Feb. 2002, [Peer-reviewed]
    English, Scientific journal
  • Continuous-Flow Chemical Processing on a Microchip by Combining Microunit Operations and a Multiphase Flow Network
    Manabu Tokeshi, Tomoko Minagawa, Kenji Uchiyama, Akihide Hibara, Kiichi Sato, Hideaki Hisamoto, Takehiko Kitamori
    Analytical Chemistry, 74, 7, 1565, 1571, 21 Feb. 2002, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • Stabilization of Liquid Interface and Control of Two-Phase Confluence and Separation in Glass Microchips by Utilizing Octadecylsilane Modification of Microchannels
    Akihide Hibara, Masaki Nonaka, Hideaki Hisamoto, Kenji Uchiyama, Yoshikuni Kikutani, Manabu Tokeshi, Takehiko Kitamori
    Analytical Chemistry, 74, 7, 1724, 1728, 16 Feb. 2002, [Peer-reviewed]
    English, Scientific journal
  • Pile-up glass microreactor
    Yoshikuni Kikutani, Akihide Hibara, Kenji Uchiyama, Hideaki Hisamoto, Manabu Tokeshi, Takehiko Kitamori
    Lab on a Chip, 2, 4, 193, 193, 2002, [Peer-reviewed]
    English, Scientific journal
  • Fast and high conversion phase-transfer synthesis exploiting the liquid–liquid interface formed in a microchannel chip
    Hideaki Hisamoto, Takumi Saito, Manabu Tokeshi, Akihide Hibara, Takehiko Kitamori
    Chemical Communications, 24, 2662, 2663, 04 Dec. 2001, [Peer-reviewed]
    English, Scientific journal
  • On-Chip Integration of Sequential Ion-Sensing System Based on Intermittent Reagent Pumping and Formation of Two-Layer Flow
    Hideaki Hisamoto, Takayuki Horiuchi, Kenji Uchiyama, Manabu Tokeshi, Akihide Hibara, Takehiko Kitamori
    Analytical Chemistry, 73, 22, 5551, 5556, 28 Sep. 2001, [Peer-reviewed]
    English, Scientific journal
  • Photothermal Temperature Control of a Chemical Reaction on a Microchip Using an Infrared Diode Laser
    Maxim N. Slyadnev, Yuki Tanaka, Manabu Tokeshi, Takehiko Kitamori
    Analytical Chemistry, 73, 16, 4037, 4044, 12 Jul. 2001, [Peer-reviewed]
    English, Scientific journal
  • Morphological Dependence of Radiative and Nonradiative Relaxation Energy Balance in Photoexcited Aryl Ether Dendrimers as Observed by Fluorescent and Thermal Lens Spectroscopies
    Yuki Wakabayashi, Manabu Tokeshi, Akihide Hibara, Dong-Lin Jiang, Takuzo Aida, Takehiko Kitamori
    The Journal of Physical Chemistry B, 105, 19, 4441, 4445, 25 Apr. 2001, [Peer-reviewed]
    English, Scientific journal
  • Determination of Subyoctomole Amounts of Nonfluorescent Molecules Using a Thermal Lens Microscope:  Subsingle-Molecule Determination
    Manabu Tokeshi, Marika Uchida, Akihide Hibara, Tsuguo Sawada, Takehiko Kitamori
    Analytical Chemistry, 73, 9, 2112, 2116, 29 Mar. 2001, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • On-Chip Integration of Neutral Ionophore-Based Ion Pair Extraction Reaction
    Hideaki Hisamoto, Takayuki Horiuchi, Manabu Tokeshi, Akihide Hibara, Takehiko Kitamori
    Analytical Chemistry, 73, 6, 1382, 1386, 10 Feb. 2001, [Peer-reviewed]
    English, Scientific journal
  • Determination of Carcinoembryonic Antigen in Human Sera by Integrated Bead-Bed Immunoasay in a Microchip for Cancer Diagnosis
    Kiichi Sato, Manabu Tokeshi, Hiroko Kimura, Takehiko Kitamori
    Analytical Chemistry, 73, 6, 1213, 1218, 10 Feb. 2001, [Peer-reviewed]
    English, Scientific journal
  • Acceleration of an enzymatic reaction in a microchip
    Yuki Tanaka, Maxim N. Slyadnev, Kiichi Sato, Manabu Tokeshi, Haeng-Boo Kim, Takehiko Kitamori
    Analytical Sciences, 17, 7, 809, 810, 2001, [Peer-reviewed]
    English, Scientific journal
  • Integration of a wet analysis system on a glass chip: determination of Co(ii) as 2-nitroso-1-naphthol chelates by solvent extraction and thermal lens microscopy
    Tomoko Minagawa, Manabu Tokeshi, Takehiko Kitamori
    Lab on a Chip, 1, 1, 72, 72, 2001, [Peer-reviewed]
    English, Scientific journal
  • Optimization of the optical-scheme design for photothermal-lens microscopy in microchips
    MA Proskurnin, M Tokeshi, MN Slyadnev, T Kitamori
    Analytical Sciences, 17, S454, S457, 2001, [Peer-reviewed]
    English, Scientific journal
  • Infrared Absorption Characteristics of Large-Sized Spherical Aryl-Ether Dendrimers
    Yuki Wakabayashi, Manabu Tokeshi, Akihide Hibara, Dong-Lin Jiang, Takuzo Aida, Takehiko Kitamori
    Analytical Sciences, 16, 12, 1323, 1326, 17 Dec. 2000, [Peer-reviewed]
    English, Scientific journal
  • Non-contact photothermal control of enzyme reactions on a microchip by using a compact diode laser
    Yuki Tanaka, Maxim N Slyadnev, Akihide Hibara, Manabu Tokeshi, Takehiko Kitamori
    Journal of Chromatography A, 894, 1-2, 45, 51, Oct. 2000, [Peer-reviewed]
    English, Scientific journal
  • Integration of a microextraction system
    Manabu Tokeshi, Tomoko Minagawa, Takehiko Kitamori
    Journal of Chromatography A, 894, 1-2, 19, 23, Oct. 2000, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • Molecular Transport between Two Phases in a Microchannel
    Kiyoshi Sato, Manabu Tokeshi, Tsuguo Sawada, Takehiko Kitamori
    Analytical Sciences, 16, 5, 455, 456, 17 May 2000, [Peer-reviewed]
    English, Scientific journal
  • Integration of an immunosorbent assay system: Analysis of secretory human immunoglobulin A on polystyrene beads in a microchip
    Kiichi Sato, Manabu Tokeshi, Tamao Odake, Hiroko Kimura, Takeshi Ooi, Masayuki Nakao, Takehiko Kitamori
    Analytical Chemistry, 72, 6, 1144, 1147, 15 Mar. 2000, [Peer-reviewed]
    English, Scientific journal
  • Integration of a Microextraction System on a Glass Chip:  Ion-Pair Solvent Extraction of Fe(II) with 4,7-Diphenyl-1,10-phenanthrolinedisulfonic Acid and Tri-n-octylmethylammonium Chloride
    Manabu Tokeshi, Tomoko Minagawa, Takehiko Kitamori
    Analytical Chemistry, 72, 7, 1711, 1714, 26 Feb. 2000, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • Integration of Flow Injection Analysis and Zeptomole-Level Detection of the Fe(II)-o-Phenanthroline Complex
    Kiyoshi Sato, Manabu Tokeshi, Takehiko Kitamori, Tsuguo Sawada
    Analytical Sciences, 15, 7, 641, 645, 15 Jul. 1999, [Peer-reviewed]
    English, Scientific journal
  • Sub-Zeptomole Detection in a Microfabricated Glass Channel by Thermal-Lens Microscopy
    Kiyoshi Sato, Hiroaki Kawanishi, Manabu Tokeshi, Takehiko Kitamori, Tsuguo Sawada
    Analytical Sciences, 15, 6, 525, 529, 23 Jun. 1999, [Peer-reviewed]
    English, Scientific journal
  • Single- And countable-molecule detection of non-fluorescent molecules in liquid phase
    Manabu Tokeshi, Marika Uchida, Kenji Uchiyama, Tsuguo Sawada, Takehiko Kitamori
    Journal of Luminescence, 83-84, 261, 264, Elsevier, 1999, [Peer-reviewed]
    English, Scientific journal
  • Long-term energy storage of dendrimers
    Yuki Wakabayashi, Manabu Tokeshi, Dong-Ling Jiang, Takuzo Aida, Takehiko Kitamori
    Journal of Luminescence, 83-84, 313, 315, Elsevier, 1999, [Peer-reviewed]
    English, Scientific journal
  • Photoionization Threshold of Perylene on Water Surface as Measured by Synchrotron Radiation
    Takanori Inoue, Shin-ya Sasaki, Manabu Tokeshi, Teiichiro Ogawa
    Chemistry Letters, 27, 7, 609, 610, Oxford University Press (OUP), 01 Jul. 1998, [Peer-reviewed]
    English, Scientific journal, Abstract

    Photoionization efficiency of perylene on water surface was measured in the 165-260 nm region by synchrotron radiation. The photoionization threshold was determined to be 5.9 eV and agreed well with that determined in the laser two-photon ionization. This finding indicates that the water surface is more hydrophobic than its bulk.
  • Development of Tunable Ultraviolet Laser System Synchronizing Precisely with Synchrotron Radiation Pulses from UVSOR               
    Masakazu Mizutani, Manabu Tokeshi, Atsunari Hirata, Koichiro Mitsuke
    Journal of Synchrotron Radiation, 4, 6, 13, 1997, [Peer-reviewed]
    English, Scientific journal
  • Doppler Profiles of the Balmer-α and -β Lines of the Excited Hydrogen Atoms (n = 3,4) Produced in Ar+-C2H6 Collisions
    Manadu Tokeshi, Keiji Nakashima, Teiichiro Ogawa
    Chemistry Letters, 25, 11, 943, 944, Oxford University Press (OUP), 01 Nov. 1996, [Peer-reviewed], [Lead author]
    English, Scientific journal, Abstract

    The Doppler profiles of the Balmer lines are very broad; their width decreases at lower ion energies. The translational energy distributions of H* calculated from the Doppler profile have two major components at about 10 eV and at about 100 eV for 2.5 keV of Ar+.
  • Dissociative excitation of aliphatic hydrocarbons (C2H2n: n = 1, 2, 3) by fast argon ion impact: Rovibrational distribution of CH(A2Δ)
    Manabu Tokeshi, Keiji Nakashima, Teiichiro Ogawa
    Chemical Physics, 206, 1-2, 237, 243, Elsevier BV, May 1996, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • Dissociation of aliphatic hydrocarbons by controlled electron impact: Vibrational and rotational energy distributions of the excited CH radicals
    Manabu Tokeshi, Keiji Nakashima, Teiichiro Ogawa
    Chemical Physics, 203, 2, 257, 266, Elsevier BV, Feb. 1996, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • Direct Collisional Scattering of the Excited Hydrogen Atom: Doppler Profile Analysis in the Fast Ar+ Ions Collisions with Acetylene and Ethylene               
    Manabu Tokeshi, Keiji Nakashima, Teiichiro Ogawa
    Chemical Physics Letters, 263, 783, 788, 1996, [Peer-reviewed], [Lead author]
    English, Scientific journal
  • Rovibrational Distributions of CH(B 2.SIGMA.-) Produced in Electron-C2H2 Collisions
    Kenji Furuya, Akihiro Matsuo, Manabu Tokeshi, Teiichiro Ogawa
    The Journal of Physical Chemistry, 99, 38, 13772, 13777, American Chemical Society (ACS), Sep. 1995, [Peer-reviewed]
    English, Scientific journal
  • Rovibrational Distributions of CH(A2Δ) Produced in e-C2H2 Collisions
    Manabu Tokeshi, Keiji Nakashima, Teiichiro Ogawa
    Chemistry Letters, 22, 6, 995, 996, Oxford University Press (OUP), 01 Jun. 1993, [Peer-reviewed], [Lead author]
    English, Scientific journal, Abstract

    Emission spectra of the CH(A2Δ-X2Π) transition produced in the electron impact dissociation of acethylene have been measured. The rovibrational distributions of CH(A2Δ) depend on the electron impact energy; the rotational temperature of CH(A2Δ, v′ = 0) varied from 3200 K at 17 eV to 2500 K at 100 eV, and the ratio of the vibrational populations (P(v′ = 1)/P(v′ = 0)) varied from 0.45 at 17 eV to 0.80 at 100 eV.

Other Activities and Achievements

Books and other publications

  • Engineered and Artificial Exosomes for Non-Viral Drug Delivery Nanocarriers: Extracellular Fine Particles (Yoshinobu Baba, Rikinari Hanayama, Hidetaka Akita, Takao Yasui, eds.)               
    Masatoshi Maeki, Manabu Tokeshi
    Springer, 2025, [Joint work]
  • Microfluidic Technologies and Platforms for Protein Crystallography: Applications of Microfluidic Systems in Biology and Medicine, 2nd Edition (Manabu Tokeshi, ed.)               
    Masatoshi Maeki, Manabu Tokeshi
    Springer, 2024, [Joint work]
  • Applications of Microfluidic Systems in Biology and Medicine, 2nd Edition               
    Manabu Tokeshi
    Springer, 2024, [Editor]
  • AI・ナノ・量子による超高感度・迅速バイオセンシング               
    笠間敏博, 渡慶次学, マイクロ流体デバイスによる超早期がん診断
    シーエムシー出版, Aug. 2021, [Contributor]
  • 分析化学実技シリーズ機器分析編19 マイクロ流体分析               
    渡慶次学, 真栄城正寿, 佐藤記一, 佐藤香枝, 火原彰秀, 石田晃彦, 序論, 免疫分析(イムノアッセイ), デジタルマイクロフルイディクス
    共立出版, Oct. 2020, [Joint work]
  • Microfluidic Technologies and Platform for Protein Crystallography: Applications of Microfluidic Systems in Biology and Medicine (Manabu Tokeshi, ed.)               
    Maeki Masatoshi, Manabu Tokeshi
    Springer, May 2019, [Joint work]
  • Applications of Microfluidic Systems in Biology and Medicine               
    Manabu Tokeshi
    Springer, May 2019, [Editor]
  • Microfabrication and Microfluidic Devices for Drug Delivery: Microfluidics for Pharmaceutical Applications (Hélder A. Santos, Dongfei Liu, Hongbo Zhang, Eds.)               
    Niko Kimura, Masatoshi Maeki, Manabu Tokeshi
    Elsevier, Jan. 2019, [Joint work]
  • Micro/Nano Devices for Chemical Analysis               
    Manabu Tokeshi, Kiichi Sato
    MDPI, 2017, [Joint editor]
  • 紙を使った分析・診断チップの現状と可能性/機能紙最前線, NPO法人機能紙研究会編集, 第1部進化し続ける機能紙               
    真栄城正寿, 渡慶次学
    加工技術研究会, 2017, [Joint work]
  • Fabrication and Evaluation of Microfluidic Immunoassay Devices with Antibody-Immobilized Micrbeads Retained in Porous Hydrogel Micropillars: Microchip Diagnostics in Methods in Molecular Biology (Valérie Taly, Jean-Louis Viovy, Stéphanie Descroix eds.)               
    Toshihiro Kasama, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Springer, 2017, [Joint work]
  • Nanopillars, Nanowires and Nanoballs for DNA and Protein Analysis: Nanofluidcs, 2nd Edition, RSC Nanoscience & Nanotechnology No.41 (Joshua Edel, Aleksandar Ivanov, MinJun Kim, eds.)               
    Noritada Kaji, Takao Yasui, Manabu Tokeshi, Yoshinobu Baba
    RSC Publishing, 2016, [Joint work]
  • 診断・分析機能を集積した免疫分析チップ/バイオチップの基礎と応用               
    笠間敏博, 渡慶次学
    シーエムシー出版, 2015, [Joint work]
  • Carbon Nanotubes and Modern Nanoagriculture/Nanotechnology and Plant Sciences: Nanoparticles and Their Impact on Plants (Manzer H. Siddiqui, Mohamed H. Al-Whaibi, Mohammad Firoz, Eds.)               
    Maged F. Serag, Naritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Springer, 2015, [Joint work]
  • Size-Selective Synthesis of Ultrasmall Hydrophilic CdSe Nanoparticles in Aqueous Solution at Room Temperature/Nanoparticles in Biology and Medicine: Methods and Protocols, Methods in Molecular Biology(Mikhail Soloviev, Ed.)               
    Yeon-Su Park, Yukihiro Okamoto, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    Humana Press, 2012, [Joint work]
  • ナノピラーデバイス・ナノウォールデバイス/ナノ融合による先進バイオデバイス(民谷栄一監修)               
    安井隆雄, 渡慶次学, 馬場嘉信
    シーエムシー出版, 2011, [Joint work]
  • マイクロ分析, 光熱変換分析/改訂六版分析化学便覧               
    渡慶次 学
    丸善, 2011, [Single work]
  • PCR内蔵型DNAチップ/試料分析講座1巻DNA/RNA               
    岡本行広, 加地範匡, 渡慶次学, 馬場嘉信
    丸善, 2011, [Joint work]
  • DNA前処理/PCR・チップ/バイオチップ実用化ハンドブック               
    加地範匡, 岡本行広, 渡慶次学, 馬場嘉信
    エヌ・ティー・エス, 2010, [Joint work]
  • 医療に貢献するナノバイオ技術/遺伝子医学「ますます重要になる細胞周辺環境の科学技術-細胞の生存、増殖、機能のコントロールから再生医療まで」               
    岡本行広, 加地範匡, 渡慶次学, 馬場嘉信
    メディカルドゥ, 2009, [Joint work]
  • 熱レンズ顕微鏡/分光測定入門シリーズ第10巻顕微分光法-ナノ・マイクロの世界をみる分光法(日本分光学会編)               
    渡慶次学, 火原彰秀
    講談社サイエンティフィク, 2009, [Joint work]
  • 蛍光計測/MEMS/NEMS工学全集               
    渡慶次学, 馬場嘉信
    テクノシステム, 2009, [Joint work]
  • ナノテクノロジーを利用した超高性能DNA解析手法/マイクロ・ナノ化学チップと医療・環境・バイオ分析, 第5編応用技術               
    岡本行広, 加地範匡, 渡慶次学, 馬場嘉信
    技術教育出版, 2009, [Joint work]
  • マイクロ化学チップの特性と動作性/マイクロ・ナノ化学チップと医療・環境・バイオ分析, 第2編マイクロ化学チップの動作と原理               
    渡慶次学
    技術教育出版, 2009, [Single work]
  • Nano-Fabricated Structures for Biomolecule Analysis/Bio-Inspired Nanomaterials and Nanotechnology(Yong Zhou, Ed.)               
    Noritada Kaji, Yukihiro Okamoto, Manabu Tokeshi, Yoshinobu Baba
    Nova Publisher, 2009, [Joint work]
  • Nanopillars and Nanoballs for DNA Analysis/Nanofluidcs(J. Edel, A. J. deMello, Eds.)               
    Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    RSC Publishing, 2009, [Joint work]
  • ガラスのウェットエッチング-マイクロ化学チップの作製法/ウェットエッチングのメカニズムと処理パラメーターの最適化               
    渡慶次学, 菊谷善国
    サイエンス&テクノロジー, 2008, [Joint work]
  • Flow Analysis in Microfluidic Devices/Advances in Flow Methods of Analysis(M. Trojanowicz, Ed.)               
    Manabu Tokeshi, Takehiko Kitamori
    Wiley-VCH, 2008, [Joint work]
  • ナノバイオデバイス/ナノバイオ計測の実際               
    馬場嘉信, 渡慶次学, 加地範匡
    講談社, 2007, [Joint work]
  • ミクロ相分離/ナノバイオ辞典               
    渡慶次学
    テクノシステム, 2007, [Single work]
  • Solvent Extraction on Chips               
    Manabu Tokeshi, Takehiko Kitamori
    CRC Press, 2007, [Joint work]
  • Nanoscale DNA Analysis               
    Laili Mohmoudian, Moham, Reza Mohamadi, Noritada Kaji, Manabu Tokeshi, Yoshinobu Baba
    CRC Press, 2007, [Joint work]
  • 化学反応高度分析のためのマイクロ化学チップ~熱レンズ分光分析装置の開発/マイクロリアクターテクノロジー               
    渡慶次学
    NTS, 2005, [Single work]
  • 分子輸送制御, 化学システム設計/マイクロ化学チップの技術と応用(化学とマイクロ・ナノシステム研究会監修)               
    渡慶次学
    丸善, 2004
  • マイクロケミカルテクノロジー/コンビナトリアルテクノロジー:明日を開く‘もの作り’の新世界(鯉沼秀臣, 川崎雅司監修)               
    渡慶次学, 北森武彦
    丸善, 2004, [Joint work]
  • マイクロチップ化学プロセスの設計, 超高感度検出器, マイクロ分析化学システム/インテグレーテッド・ケミストリー(北森武彦編)               
    渡慶次学
    シーエムシー出版, 2004
  • マイクロ流路による微小バイオテクノロジー/バイオエンジニアリングマテリアル(石原一彦編)               
    渡慶次学, 佐藤記一, 北森武彦
    フロンティア出版, 2004, [Joint work]
  • マイクロ分析チップ/ナノテクノロジーハンドブックIV編 バイオ・化学を使う               
    渡慶次学
    オーム社, 2003, [Single work]
  • ナノ・マイクロテクノロジー/第6版化学便覧応用化学編I, II編基盤的化学技術, 11章次世代基盤化学技術               
    金幸夫, 渡慶次学
    丸善, 2003, [Joint work]
  • ヨクト分析-ナノをはるかに超えて/基礎から学ぶナノテクノロジー(平尾一之編)               
    渡慶次学, 北森武彦
    東京化学同人, 2003, [Joint work]
  • Micro Integrated Chemical Systems for General Use/Lab-On-A-Chip: Miniaturized Systems for (Bio) Chemical Analysis and Synthesis(R.E.Oosterbroek, A.van den Berg, Eds.)               
    Yoshikuni Kikutani, Akihide Hibara, Hideaki Hisamoto, Manabu Tokeshi, Takehiko Kitamori
    Elsevier, 2003, [Joint work]

Affiliated academic society

  • アメリカ化学会               
  • THE SOCIETY FOR CHEMISTRY AND MICRO-NANO SYSTEMS               
  • 日本分光学会               
  • 日本分析化学会               
  • 日本化学会               
  • Japan Society of Molecular Science               
  • American Chemical Society               
  • The Institute of Electrical Engineering of Japan               
  • The Spectroscopical Society of Japan               
  • The Japan Society for Analytical Chemistry               
  • The Chemical Society of Japan               
  • Royal Society of Chemistry               

Research Themes

  • Development of Applications of Engineered Lipid Particles
    Grants-in-Aid for Scientific Research
    Apr. 2024 - Mar. 2029
    渡慶次 学, 真栄城 正寿, 篠田 渉
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (S), Hokkaido University, 24H00038
  • 農業の生産性と持続性の向上を支援する簡便・低コストな画期的スマート土壌診断システムの基盤技術の開発               
    オープンイノベーション研究・実用化推進事業基礎研究ステージ(基礎重要政策タイプ)
    Jul. 2023 - Mar. 2026
    渡慶次学, 石田晃彦, 丸山隼人, 細淵幸雄, 松田憲司
    生物系特定産業技術研究支援センター, 北海道大学・北海道立総合研究機構・BIPROGY株式会社, 05010a3
  • 大麻成分検出ペーパーデバイス開発
    産学が連携した研究開発成果の展開 研究成果展開事業 研究成果最適展開支援プログラム(A-STEP) 産学共同(本格型)
    2022 - Mar. 2026
    安部寛子, 渡慶次 学, 高橋秀依
    近年、違法な大麻栽培や大麻乾燥物の国内流通が増加しており、捜査機関はその取り締まりに苦慮している。また、大麻草に含有されるカンナビノイド類にリラクゼーション・鎮痛作用等が謳われ、大麻草抽出物がセルフメディケーション製品として市販され、健康被害も報告されている。そのため、捜査機関や化粧品、食品業界からは、法規制成分であるカンナビノイド(THC)を精度よく簡便に検出する技術に高い関心が集まっている。そこで本事業では、このような製品中にTHCが含有されているか否かを簡単に正確に判定するペーパーデバイスを開発する。公的機関で利用される信頼性のあるデバイスの開発を行い、安心・安全な社会づくりに貢献する。
    科学技術振興機構, 株式会社バイオデザイン, JPMJTR224B
  • タンパク質やウイルスを簡便かつ迅速に測定可能な新しい蛍光偏光免疫分析法の開発
    科学研究費助成事業
    30 Jun. 2022 - 31 Mar. 2025
    渡慶次 学, 火原 彰秀
    日本学術振興会, 挑戦的研究(開拓), 北海道大学, 22K18434
  • 化学テロ発生現場において神経剤を検知する紙製流体デバイスの創製
    科学研究費助成事業
    01 Apr. 2020 - 31 Mar. 2023
    宮口 一, 渡慶次 学, 山口 晃巨
    吸水性の高い紙を基材とした紙製流体デバイスは、浸潤により自律的に液体が移動するため、電源やポンプが不要であり、リソースが限られるテロ現場における危険物質の検知に適していると考えられる。また、安価で大量生産が可能であることも、実用化のためには利点となる。
    令和3年度は、前年度に設計・最適化した紙製流体デバイスについて、種々の化学剤及び有機リン系農薬に対する応答性能を評価した。その結果、神経剤(サリン、タブン、VX及びRVX)は、有機リン系農薬(ジクロルボス、パラオキソン)より約1000倍高感度であることが明らかとなった。さらに、実際の現場資料において想定される有機溶媒等の妨害物質の影響についても検討した結果、種々の有機溶媒共存下においても正しく検知可能であり、かつ偽陽性を生じないことが明らかとなった。なお、DMSOで偽陽性を生じたものの、水で20倍に希釈した場合は偽陽性を生じなかったことから、測定前の希釈が偽陽性の防止及び有機リン系農薬との識別に有効であることが明らかとなった。
    さらに、ドアノブやスイッチからの難揮発性神経剤の検知を想定して、ステンレス板及びプラスチック板上に残ったVXを展開液を浸潤させた綿で拭き取り、その展開液をそのまま紙製検査チップに導入して検査した。その結果、約5 ngのVXが検知可能であった。
    以上のことから、検出性能の点においては実用化の域に達したと考え、これまでの成果をまとめて論文公表及び特許出願を行った。
    日本学術振興会, 基盤研究(C), 科学警察研究所, 20K09279
  • 育種・染色体操作を用いたサケ科魚類の魚卵アレルゲン性低減化の試み
    科学研究費助成事業
    01 Apr. 2020 - 31 Mar. 2023
    清水 裕, 笹岡 友季穂, 藤本 貴史, 平松 尚志, 石田 晃彦, 渡慶次 学, 佐伯 宏樹
    進捗状況を3項目に分けて述べる。
    1.不妊魚の作出:ニジマスの卵と凍結保存したブラウントラウトあるいはサクラマスの精子を受精し、第二極体放出阻止処理により作出された雑種三倍体候補(A:ニジマス×ブラウントラウト、B:ニジマス×サクラマス)の倍数性を調査した。その結果、候補Aでは全25個体で、候補Bでは1個体を除く30個体が三倍体であった。これらの個体はPITタグで標識し、現在も継続して飼育している。(藤本)
    2.魚卵アレルゲン検知系の構築:引き続き、ニジマス卵アレルゲンであるβ’-component(BC)のペーパー免疫分析デバイスの構築に取り組んだ。デバイスは濾紙にインクを印刷して加熱する常法により作製し、インクで囲まれた領域を分析反応ゾーンとした。分析は、反応ゾーンに新規作製した抗BC抗体を固定化して試料、酵素標識抗BC抗体、発色試薬を順に加えて行う手順とした。本手法では、従来並みの感度(検出感度:約1 ng/mL)の分析が従来の1/100の時間(約20分)で可能となった。(渡慶次、石田)
    加えて、交雑種に対応した検知系に使用する抗体の作成のため、サクラマス排卵からBCを精製し、これを家兎に免疫し抗血清を作製した。(平松)
    3.不妊化魚の魚卵アレルゲン性の調査:全23個体の不妊化三倍体ニジマスの内臓組織に含まれるBCを測定したが、全個体の筋肉には魚卵アレルギー発症リスクが認められなかった。しかし、5個体において生殖線から少量のBCが検出されたが、その内3個体は目視にて明確な生殖腺の発達が観られた。目視で生殖線の発達が確認できなかった20個体について、生殖腺の組織切片を作製・観察し、その発達状況を確認した。その結果、3個体で発達中の卵母細胞が散在しているのが確認され、生殖腺の外観だけでアレルギー発症リスクの有無を見分けるのは困難であることが判明した。(清水、佐伯、笹岡、平松)
    日本学術振興会, 基盤研究(C), 北海道大学, 20K05903
  • Development of high performance paper devices and its application development
    Grants-in-Aid for Scientific Research
    01 Apr. 2020 - 31 Mar. 2023
    渡慶次 学, 谷 博文
    本研究では、①分析性能の高い紙デバイスの研究、②免疫分析デバイスの開発、③細胞アッセイ及び細胞分離デバイスの開発、④教育ツール用デバイスの開発に取り組む。本年度は、この中の①、②、④に取り組んだ。
    ①双極性障害の治療薬であるリチウム製剤の血中濃度測定をモデル系として、高性能紙デバイスシステムを構築した。血漿分離と血漿中のリチウムイオンの検出を性質の異なる紙を利用することで、わずか1滴(20マイクロリットル)の試料量で1分以内に測定することに成功した。検出性能は、遠心分離と吸光光度計による従来法と同等であった。
    ②競合免疫分析が可能な3次元紙デバイスを開発した。流路を3次元化することで流路長を短くすることが可能となり、アッセイ時間を短縮することができた。デバイスは3層構造になっており、反応領域と検出領域を別の層にすることで、分析性能を向上させることができた。さらに、非競合免疫分析の酵素免疫分析法(ELISA)の基礎検討も実施した。
    ③紙デバイスは、安価で簡便ということから、教育ツールとして適している。しかし、濃度定量するためには、マイクロピペットによる試料導入が必要である。そこでマイクロピペット等を用いずに、サンプルに浸漬するだけで、サンプル中の測定対象の濃度を定量できる紙デバイスを開発した。アスコルビン酸とpHの同時測定が可能なデバイスを開発し、測定結果の浸漬時間依存性を評価したところ、測定結果は浸漬時間(3秒から1分)に依存しないことも確認した。測定性能も従来法を同等であることを確認した。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 20H02760
  • Convergence and a new direction for exosome researches on hybrid exosomes creation by international collaboration
    Grants-in-Aid for Scientific Research
    07 Oct. 2019 - 31 Mar. 2023
    加地 範匡, 渡慶次 学, 真栄城 正寿
    本国際共同研究では、日本・オランダ・シンガポールの各研究グループが独自に有するマイクロ・ナノテクノロジー、デバイス技術、エクソソーム分離・解析、エクソソーム高機能化、単一細胞アッセイ、細胞スフェロイドアッセイの各要素技術を結集して融合することで、再生医療やがん免疫療法に応用可能な高機能ハイブリッドエクソソームの創製を目的とする。本研究期間中、世界屈指の超微細加工技術とそれを可能とする施設を有するトウェンテ大学、基礎研究から臨床研究まで包括的に研究を行う体制が整っているシンガポール国立大学に若手研究者が3ヶ月以上滞在し、超微細加工技術から細胞スフェロイドアッセイ技術までを習得することで、エクソソームの選択的捕捉・分離・解析・高機能化から単一細胞・細胞スフェロイドアッセイが可能な統合型デバイスの研究開発をおこなうことを目指した。
    本研究の当初計画では、参画研究者がトウェンテ大学に長期滞在してデバイス作製技術の習得並びに作製と評価を行う予定であったが、昨年度に引き続いて今年度もコロナ禍のために海外渡航が叶わず、また国内での移動も多くの制限が課されていたため、オンラインディスカッションと各研究室で実施可能な基礎検討を中心に研究を行った。具体的には、外部バルス電界によるエクソソームへの外来物質導入やデバイスを用いた精製・評価法の検討を行い、最適な粒子濃度・電場強度を見出すとともに、長期保存における安定性についても評価を行った。その結果、牛乳由来エクソソームに関しては、粒子濃度が高く、電場強度が強いほど、外来物質の導入効率が高まることを明らかとした。また3ヶ月間の凍結保存においては、エクソソームの粒径などの正常に影響がないことも分かった。
    Japan Society for the Promotion of Science, Fund for the Promotion of Joint International Research (Fostering Joint International Research (B)), Kyushu University, 19KK0140
  • オンサイト蛍光偏光イムノアッセイ装置の開発               
    先端計測分析技術・機器開発プログラム
    Oct. 2016 - Mar. 2021
    渡慶次 学
    JST, Principal investigator, Competitive research funding
  • Isotope Separation by Microchip
    Grants-in-Aid for Scientific Research
    28 Apr. 2011 - 31 Mar. 2017
    Hazama Ryuta, OGATA YOSHIMUNE, TOKESHI MANABU, MIYAKE RYO
    We proved that liquid-liquid extraction (LLE) with crown-ether which was awarded a Nobel prize in 1987, can be utilized not only for ion separation, but also for isotope separation. Previously it was found that multistage process of back extraction will be impractical, due to its Ca concentration reduction with the order of 6 after LLE's iteration of 4, even though the largest enrichment of 8 % was obtained at LLE's iteration of 3. Thus, we developed that the new procedure that a valuable crown-ether organic solution can be recycled by using just a water and its Ca concentration can be maintained/kept with just a 20-30 % reduction, simultaneously. This trade-off relation between Ca concentration (partition coefficient) and separation factor was verified and its separation factor of this new method was found to be 1.0010±0.0003 (about 1/10 compared with the back extraction) and we cleared these two obstacles (Ca concentration and separation factor)for a multistage process.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), 23561013
  • 小型蛍光偏光測定デバイスの開発               
    科学研究費補助金挑戦的萌芽研究
    2012 - Mar. 2015
    渡慶次 学
    JSPS, Principal investigator, Competitive research funding
  • 次世代診断チップの開発とその臨床診断への応用               
    科学研究費補助金基盤研究A
    2012 - Mar. 2015
    渡慶次 学
    JSPS, Principal investigator, Competitive research funding
  • Development of diagnosis and therapy-integrated medical devices with liposomes containing quantum dots and hollow nanofibers against brain tumors.
    Grants-in-Aid for Scientific Research
    01 Apr. 2011 - 31 Mar. 2014
    MIZUNO Masaaki, TOKESHI Manabu, OKAMOTO Yukihiro, PARK Yeon-su, YUKAWA Hiroshi, OHMORI Masato
    Malignant brain tumors are difficult to remove completely due to their cellularity characteristics with borderless diffusion, thus the eradicating brain tumor at the cellular level is strongly desired to obtain a good prognosis. In this study, we first assessed the efficiency of Quantum Dots (QDs) conjugated with Transferrin (Tf) (QDs-Tf) and hollow nanofibers for specific imaging of tumor cells. As a result, we found that imaging brain tumor cells using QDs-Tf is effective in detecting tumor cells at the cellular level with clinical applications. Moreover, we developed another technique to pick up free electron from QDs and then we comfirned that it could induce tumor cell death. These data suggest that the diagnosis and therapy-integrated medical devices with liposomes containing QDs and hollow nanofibers are useful for the treatment against formidable malignant brain tumors.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, 23390346
  • MENDで拓く遺伝子治療への道:遺伝子の運び屋からナノマシンへ
    科学研究費助成事業
    31 May 2010 - 31 Mar. 2014
    原島 秀吉, 山田 勇磨, 中村 孝司, 兵藤 守, 馬場 嘉信, 篠原 康雄, 小暮 健太朗, 紙谷 浩之, 渡慶次 学, 松尾 保孝, 秋田 英万
    パッチワーク法による新しいMEND構築方法を確立し一枚膜でコア粒子をパッケージする新しい方法を開発し、平均粒子径が25nm程度でゼータ電位が-40mV程度の構造体を得ることに成功し、P-MENDと命名した。D-MEND法と組み合わせることでPD- MEND(3枚膜構造)を構築したところ、市販の試薬より高い活性を示した。マイクロ流体デバイスを開発し、最小粒径30nmのMENDを作製することに成功した。一方でマイクロ流路作製についての検討し、ナノインプリント手法によりガラスマイクロ流路の量産が可能であることをしめした。また、シースフローと電場を利用したマイクロフリーフロー電気泳動デバイスの構造・分離条件の最適化を行い、MEND精製に適用することでMENDの定性的かつ定量的評価法を確立した。KALAペプチドを導入した脂質膜封入型ナノ粒子にがん抗原等をコードした遺伝子を封入することで、抗腫瘍活性を得ることに成功した。また、本粒子は細胞に対し免疫活性化効果を有することを示し、その機構に細胞質内DNAセンサーが関与することを示唆する結果を得た。酵素耐性RNAアプタマーの単離に世界で始めて成功した。Mt移行性ペプチドを搭載したMTS-MITO-Porterを構築し、生細胞内での選択的Mt送達システムを開発し、MTS-MITO-Porterは従来型MITO-Porterと比較してミトコンドリア移行能が飛躍的に上昇した。GAL4とVP16の融合蛋白質を用いる自己活性化システムを構築し、reporterプラスミドDNAの単独投与に比べて数十倍にルシフェラーゼ活性が上昇した。アンチセンスRNA (ASO)をMITO-Porterを用いて細胞Mtに送達し、ミトコンドリアmRNAを40%抑制し、さらに標的mRNAがコードする内因性Mtタンパク質の発現量が低下した。
    日本学術振興会, 基盤研究(S), 北海道大学, 22229001
  • 食品中の抗生物質検出のためのマイクロチップ蛍光偏光免疫分析法の開発               
    二国間交流事業
    2012 - Mar. 2014
    渡慶次 学
    JSPS, Principal investigator, Competitive research funding
  • 超高性能マイクロチップ電気泳動による糖たんぱく質のアイソフォーム解析               
    二国間交流事業
    2011 - Mar. 2013
    渡慶次 学
    JSPS, Principal investigator, Competitive research funding
  • Development of Microdevices for Cell Assay
    Grants-in-Aid for Scientific Research
    2008 - Mar. 2011
    TOKESHI Manabu, BABA Yoshinobu, KAJI Noritada, CHAN Yu
    We developed a micro device that a series of bioassay from the cell culture to the gene expression analysis is possible. Two kinds of devices were developed : a device that enables circumfusion culture of suspension cells (yeast) while exchanging media, and a genetic analysis device that enables real-time PCR. An integrated device of these two devices was successfully developed.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, Principal investigator, Competitive research funding, 20310072
  • 流路型免疫分析チップの開発               
    産業技術研究助成事業費助成金
    2007 - Mar. 2011
    渡慶次 学
    NEDO, Principal investigator, Competitive research funding
  • Development of single genome DNA methylation detection device for epigenetics analysis
    Grants-in-Aid for Scientific Research
    2008 - 2011
    BABA Yoshinobu, TOKESHI Manabu, KAJI Noritada, OKAMOTO Yukihiro, ZHANG Yong, WANG Jun, YASUI Takao
    We successfully developed novel DNA methylation analysis method. Our method elongates single DNA by flow or nanospace in the microfluidic device and detect methylation site with methylation point specific quantum-dots. Therefore, we need no troublesome procedures like PCR and can identify the location of methylation site as well as can detect methylation in single molecule level, which cannot attain by current methylation analysis method. These advantages would permit our method to be applied for medical diagnosis.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Nagoya University, 20241032
  • Enrichment of Double Beta Decay Isotope by Crown-ether & Microchip Chemical Plant
    Grants-in-Aid for Scientific Research
    2007 - 2010
    HAZAMA Ryuta, KISHIMOTO Tadafumi, SAKUMA Yoichi, TANIMIZU Masaharu, TOKESHI Manabu
    The double beta decay, which can study the absolute neutrino mass and its Majorana nature, is one of the most important research and we will start CANDLES experiment soon utilizing 300kg of CaF_2 crystals containing of ^<48>Ca with the highest Q-value among double beta decay nuclei. The calcium cannot be enriched by centrifugal and diffusion separations and electromagnetic separation costs much and its production is limited only for tens of grams. We developed chemical isotope separation by liquid-liquid extraction with crown-ether and obtained the highest separation factor of 1.012(2℃)~1.014(20℃) (about two times of Jepson's 1.008 and five times of resin's 1.003) and showed the validity of microchip for the extraction process by gas-liquid two phase isotope exchange reaction and micromixer for emulsification droplets.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hiroshima University, 19540300
  • Toward Practical Usz of Microchip Immunoassay Systems
    Grants-in-Aid for Scientific Research
    2006 - Mar. 2009
    MANABU Tokeshi, KITAMORI Takehiko
    We have developed three types of new immunoassay formats.
    A microchip-based semi-automated heterogeneous immunoassay was developed wherein a flow injection-like system and repeatable-use gel were employed. A regeneration buffer for antigen-antibody interaction of brain natriuretic peptide (BNP) was found which did not lose binding activity of the antibody on the gels and integration of such an immunoassay scheme into a semi-automated microfluidics system would facilitate repeated-use heterogeneous immunoassay. The concentration of BNP in the range of 0.1-100 pg/ml was successfully determined using the system and protocol developed here.
    We developed a new platform for chip-based immunoassay to create the effective reaction sites of immunological reaction between antigen and antibody. The reaction sites were fabricated by the UV photopolymerization of a solution of photopolymer and the antibody-immobilized polystyrene beads. Our platform has many advantages ; (i) rapid analysis (a few minutes), (ii) easy handling (no need pump and valve), (iii) low-cost (disposable), (iv) small volume(I droplets(0.25gL)of sample and reagents), and(v)high sensitivity(2 orders higher than conventional method). In order to evaluate our platform, we carried out(sandwich)immunoassay for a-fetoprotein(AFP), which is known as a tumor marker. In the case of 1-min incubation(total assay time : ca. 3 min), the limit of detection (LOD) was 10 ng/ml. This value is compared to that of conventional method using a microtiter plate with 4 h of total assay time. The LOD for &min incubation was 2 orders lower than that of conventional one.
    We developed an optimized microchip-based fluorescence polarization immunoassay (FPIA) . Microchip-based FPIA was simple and rapid because it did not require several processes such as washing and reflowing and immobilization of antibodies or antigens in a channel. The quantitative analysis of theophylline was performed in short analysis time (65 seconds) with simple operation and reduced samples. The microchip-based FPIA will find a frequent use as point-of-care testing in clinical field. Furthermore we observed the behavior of fluorescence polarization after antigens and antibodies are mixed in a microchannel. The information will lead to the development of immunoassays using fluorescence polarization.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Principal investigator, Competitive research funding, 17310087
  • マイクロ・ナノ反応場を利用した革新的アクチノイド分離法の開発               
    原子力システム開発事業
    2005 - Mar. 2008
    渡慶次 学
    文部科学省, Principal investigator, Competitive research funding
  • ファンクショナル熱レンズ顕微鏡               
    先端計測分析技術・機器開発事業
    2005 - Mar. 2008
    渡慶次 学
    JST, Principal investigator, Competitive research funding
  • マイクロ空間における新規免疫化学反応場の創出               
    川崎市新技術・新製品開発等支援事業補助金
    2006 - Mar. 2007
    渡慶次 学
    川崎市, Principal investigator, Competitive research funding
  • 心筋細胞の駆動力を電気エネルギーに変換するナノファイバー型バイオ発電素子の開発
    科学研究費補助金萌芽研究
    2004 - Mar. 2006
    渡慶次 学
    本研究は、生物の最小単位である細胞というパーツを用いて、微小機械及びナノ材料と結びつけるという全く新しい概念に基づいて、デバイス設計を行う斬新な試みである。これまでに様々なMEMSデバイス、発電素子、燃料電池が提案されてきたが、提案するデバイスは従来とは全く異なるアプローチによる独創的な新原理デバイスである。細胞と無機材料を融合させ、生体自ら発生するエネルギーやリズムを運動エネルギー、電気エネルギーに変換するという生体融合機能デバイスの創成である。
    そこで、心筋細胞を駆動源として、細胞を用いた柔らかいマイクロアクチュエータを実現できると考え,デバイスの設計及び基礎実験を行ってきた。細胞そのものを材料として、力学的機能と化学的機能を持ち合わせた新規なアクチュエータであり、構想及びデバイスの基本原理は非常に独創的である。基礎実験により、化学エネルギー(グルコース・酸素供給)だけで動作するアクチュエータを既に確認しており、試作したバイオマイクロアクチュエータの発生力は細胞あたり数nNから数十μNという大きな力を発生することが分かった。そこで、ナイロン糸上での心筋細胞の接着性をみるために,ナイロン糸上での心筋細胞培養実験を行った。ナイロン糸に接着している心筋細胞が観察でき,培養2日後には,拍動も確認できた。圧電ファイバーの伸縮応答実験より,心筋細胞を効率よくナイロン糸上に配向させることができれば,電圧が得られることがわかった。
    JSPS, 萌芽研究, (財)神奈川科学技術アカデミー, Principal investigator, Competitive research funding, 16651081
  • マイクロチップを用いた再処理工場用分析装置の開発               
    革新的実用原子力技術開発費補助金
    2003 - Mar. 2005
    渡慶次 学
    経済産業省, Principal investigator, Competitive research funding
  • 簡易型マイクロチップの実用化研究               
    基盤技術研究促進事業
    2001 - Mar. 2004
    渡慶次 学
    NEDO, Principal investigator, Competitive research funding
  • 暗視野およびパームトップ熱レンズ顕微鏡の開発
    科学研究費助成事業
    2000 - 2002
    北森 武彦, 火原 彰秀, 久本 秀明, 渡辺 訓行, 渡慶次 学
    本研究は熱レンズ顕微鏡の更なる超高感度化と実用化を視野に入れ、暗視野光熱変換顕微鏡と可搬性の高いパームトップサイズ熱レンズ顕微鏡を開発することを目的とする。
    1.暗視野光熱変換顕微鏡の開発
    市販の生物顕微鏡を励起光と検出光の2本のレーザー光を導入できるように改良して、暗視野型光熱変換顕微鏡を作製した。作製した暗視野光熱変換顕微鏡を用いて励起光吸収用色素を内包したポリスチレン(80nm)粒子分散水を測定したところ、セル壁面で光が散乱され、原理的にバックグランドフリーである暗視野配置で高いバックグランド信号が発生していることがわかった。これを解決するために対物レンズと光検出器の間にピンホールユニットを作製し、セル壁面からの散乱光を排除して焦点付近からの光のみを通過・検出する(擬似共焦点配置)ようにした。これによりバックグランドを4桁低減することに成功した。
    2.パームトップサイズ熱レンズ顕微鏡の開発
    熱レンズ顕微鏡を小型化するためには、光源や光学系の小型化が必要である。熱レンズ顕微鏡の構成要素である励起光と検出光の焦点差を調整する機構と対物レンズを、色収差を持つ円筒形微小レンズに置き換えた新しい光学システムを設計し、作製した。既存のシステムと比較し、作製したシステムを評価したところ、小型レンズを用いた場合に特有のノイズが発生することを見いだした。今後、微小レンズ固定法の改良によりこのノイズを低減する予定である。
    日本学術振興会, 基盤研究(B), 東京大学, 12555233
  • マイクロチップを用いた高速高感度な内分泌拡散物質および関連物質の分析
    科学研究費助成事業
    2001 - 2001
    北森 武彦, 渡慶次 学, 木村 博子, 久本 秀明, 佐藤 記一
    マイクロチップを用いた高速高感度な内分泌撹乱物質および関連化合物の簡便迅速な分析システムを開発することを目標として、マイクロチップを用いたアッセイシステムの開発を行った。モデルケースとして小型海産巻き貝一個体中に微量含まれる性ホルモン17β-estradiolの定量を目標にした。
    数cm角のパイレックスガラス基板中に、深さ100μm、幅250μmで、中央部のみビーズをせき止めるために深さを10μmにしたマイクロチャネルを作製した。このチップに反応固相として直径15-50μm程度のポリスチレンビーズを導入し、ここに試料および各種試薬溶液を添加し、チップ内でそのまま抗原抗体反応および洗浄操作、酵素反応などを行った。生じた酵素反応生成物の検出には高感度な分析法である熱レンズ顕微鏡を用いた。
    作製したチップにあらかじめ抗17β-estradiol抗体を吸着させたビーズを導入した後、シリンジポンプを用いて17β-estradiolを含む試料と一定量のペルオキシダーゼ標識した17β-estradiolを混合した溶液を流し入れ、競合的に抗原抗体反応させた。未反応物を洗浄後、酵素基質を導入して酵素反応させ、そこで生成する発色物質を下流部で検出することにより定量を試みた。
    その結果、再現性はやや悪いものの、1-1,000pg/mLの比較的低濃度の濃度範囲で検量線を作成することが出来た。アッセイに必要な試料体積が極めて少量であることとあわせると、小型の巻き貝一個体からの抽出液から測定するのに充分な感度を有していることが明らかとなった。開発した方法では半日以上かかっていた分析を30分程度で終えることができ、分析時間の短縮も実現した。本システムは生体中の微量な環境ホルモン及び関連化合物の迅速簡便な分析手法として極めて有効な手法となることが期待できる。
    日本学術振興会, 特定領域研究(A), 東京大学, 13027219
  • 液相マイクロキャビティリングダウン分光法の開発と液相微小空間の超高感度検出
    科学研究費助成事業
    2000 - 2001
    渡慶次 学
    本年度は研究実施計画に基づけば、昨年度作製した微細流路(マイクロチャネル)を利用したキャビティ(多重反射セル)を用いてキャビティリングダウン(CRD)測定システムを評価する予定になっていた。しかし、昨年度作製したキャビティは測定条件を満足させるに至らなかったので、本年度の最初はキャビティの作製を行なった。
    1.キャビティの作製
    昨年度は、加熱式真空蒸着器でガラス基板にクロムを蒸着してキャビティを作製したが、クロムの膜厚にばらつきがあり、キャビティ表面で光散乱され、透過率が悪かった。そこで、本年度はスパッタリングによって、精密に膜厚を制御してガラス表面にクロム薄膜を作製した。これにより、キャビティ表面における光散乱が抑えられ、キャビティを作製することができた。
    2.測定システムの評価
    昨年度試作した顕微CRD測定システムを用いて液相CRD測定を行なった。試料はサンセットイエロー(色素)水溶液を用いた。キャビティ長が50〜100μmの場合、溶媒の散乱が大きく、測定はできなかった。キャビティ長が10μmの場合は、CRD信号が得られ、原理的に液相CRD測定が可能であることが実証できた。感度に関しては、吸光法とほとんど変わらず、今後キャビティ長をさらに短くするなどの改良を加えれば、高感度が可能だと考えられる。
    日本学術振興会, 奨励研究(A), (財)神奈川科学技術アカデミー, 12750720
  • 人工ナノメートル空間中液相分子の高速分光法および反応ダイナミクス制御法の開発
    科学研究費助成事業
    2000 - 2001
    北森 武彦, 火原 彰秀, 渡慶次 学
    本研究では、溶液を特長づけるの最小構成単位と考えられているクラスターの反応ダイナミクス計測を光熱変換分光法とマイクロチップ技術の利点を活用して実現することを目指している。溶液クラスターの大きさの数倍から数百倍の大きさと考えられる10〜数100nmの微小空間に液体を閉じこめ、測定することより、通常の大きさでは困難なバルク液体との情報を分離することを着想した。
    1.ナノ空間の作製 ナノ空間の作製には、電子線リソグラフィー・高速原子線加工法を用いた。また、溶液の導入路として幅190μmのチャネルをサンドブラストエッチングで作製した。ナノ空間として完成させるために、厚さ170μmの石英基板をふっ酸接合法にて接合した。溶液の導入には毛細管現象を利用する方法を利用した。ナノ空間として、幅330nm・深さ220nmの流路(330nm空間)・幅850nm・深さ620nmの流路(850nm空間)を、対照のバルク空間として幅250μm・深さ100μmの流路(250,000nm空間)を測定に用いた。
    2.蛍光寿命測定と空間サイズ効果 ローダミンB(RB)水溶液、スルホローダミン101(SR101)水溶液、ローダミン6G(R6G)水溶液を測定した。どの色素の場合もサイズに依存して波形が変化した。RBの場合には空間が小さくなるほど寿命が長くなり、SR101・R6Gの場合には、330nm空間のみ寿命が短くなることがわかった。寿命のサイズ依存は溶液の濃度にはほとんど依存せず、人工ナノ空間の溶媒物性を示していると考えられる。過去の文献等の知見より、SR101・R6Gの寿命の変化は誘電率変化に、RBの寿命変化は粘性変化に対応づけられると考えた。この変化の原因について、ガラス壁面の電荷などの影響により溶液クラスターの性質が顕在化してきているのではないかと考えられる。
    ナノメートルサイズの空間を人工的に加工し、その中で溶液の分光測定した例はこれまでになく、世界にさきがけナノ空間の液相化学が実現できたといえる。
    日本学術振興会, 特定領域研究(A), 東京大学, 12042218
  • Construction of Micro Bioanalytical Chemistry Lab,Systems and Single Cellular Biochemistry Integrated on a Glass Chip
    Grants-in-Aid for Scientific Research
    1999 - 2000
    YAMAZAKI Sunao, NAKAO Masayuki, SHOJI Shuichi, KITAMORI Takehiko, TOKESHI Manabu, KIMURA Hiroko
    We have developed fundamental unit operations essential to integration of biochemical analysis, collaborating with the research project from Kanagawa Academy of Science and Technology (KAST).
    The integrated chemical systems have desirable characteristics, such as reduction in reagent consumption, waste and analysis time. Taking these advantages, we have demonstrated many applications, including solvent extraction, flow-injection analysis, laser reaction control, enzymatic reaction and immunoassay. We also developed ultra sensitive detection device, thermal lens microscope and apply this to single-cell imaging.
    The microspace in the microchannel is characterized by the large specific interfacial area and short diffusion distance, and these characteristics may contribute to highly efficient extraction and mixing with much shorter time than general method. The integration of wet analysis of heavy metal ions such as cobalt and iron leads to a considerable reduction in analyzing time. The time for extraction in the integrated system was about tenfold shorter than a conventional system using a separately funnel and mechanical shaker. Moreover, troublesome operations could be omitted.
    We have also integrated the immunoassay system using solid surface. This integration reduced the time necessary for the overall CEA analysis from 2d to 35min. Moreover, when serum samples were assayed with this system, there was a high correlation with the conventional ELISA. These results showed the applicability of integrated analytical systems.
    Thermal lens microscope could detect nonfluorescent biological substances with extremely high sensitivity without and labeling materials and had a high spatial resolution of 〜1_m. This system was applied to monitoring of cytochrome c distribution in a neuroblastoma-glioma hybrid cell cultured in the microflask fabricated in a glass microchip. Cytochrome c release from mitochondria to cytosol during the apoptosis process was successfully monitored with this system.
    The results of this research will bring very welcome developments to biochemical studies.
    Japan Society for the Promotion of Science, Grant-in-Aid for University and Society Collaboration, THE UNIVERSITY OF TOKYO, 11794006

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