Einaga, Yasuaki



Faculty of Science and Technology, Department of Chemistry (Yagami)



Related Websites

External Links

Career 【 Display / hide

  • 1997.04

    理化学研究所 ,ジュニアリサーチアソシエイト

  • 1998.04

    日本学術振興会 ,特別研究員

  • 1999.11

    東京大学 ,助手

  • 2001.04

    慶應義塾大学理工学部化学科, 専任講師

  • 2003.04

    慶應義塾大学理工学部化学科, 助教授/准教授

display all >>

Academic Background 【 Display / hide

  • 1994.03

    The University of Tokyo, Faculty of Science

    University, Graduated

  • 1996.03

    The University of Tokyo, Graduate School, Division of Science, 化学専攻

    Graduate School, Completed, Master's course

  • 1999.03

    The University of Tokyo, Graduate School, Division of Science, 応用化学専攻

    Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide

  • 博士(工学), The University of Tokyo, 1999.03


Research Areas 【 Display / hide

  • Nanotechnology/Materials / Functional solid state chemistry (Functional Material Chemistry)


Books 【 Display / hide

  • Diamond Electrodes: Fundamentals and Applications

    Einaga Y., Diamond Electrodes: Fundamentals and Applications, 2022.01

     View Summary

    This book introduces the recent development in Japan of diamond electrodes, which has attracted much attention in the world. For example, electrochemical sensors using diamond electrodes are now being utilized commercially. Newly developing applications such as electrochemical organic synthesis including CO2 reduction are also expected to form an important future technology. Those emerging applications to various fields which are receiving increasing attention are described in detail here. This book is useful not only for students who would like to begin their study of diamond electrodes but also for industries that are exploring novel electrochemical applications.

  • Modified Boron-Doped Diamond Electrodes for Sensors and Electroanalysis

    Jiwanti P.K., Atriardi S.R., Putri Y.M.T.A., Ivandini T.A., Einaga Y., Diamond Electrodes: Fundamentals and Applications, 2022.01

     View Summary

    Boron-doped diamond (BDD) has been established as a superior electrode among other conventional solid electrodes due to its unique properties, such as very low background current, wide potential window, and high physical and chemical stability. However, in compare to metal electrodes, BDD has much lower kinetic activity in some important chemical reactions, which causes limitation for sensor and biosensor applications. Modification of BDD surface with redox-active particles/compounds was reported to facilitate electron transfer between the BDD substrate and analytes with a significant reduction in activation overpotential; therefore, the catalytic activity and sensitivity are improved. In addition, the modification can increase the selectivity in some reactions. On the other hand, to have a stable modified surface of BDD electrode is not easy, since the main composition of BDD is carbon atoms with sp3 configuration, which is very compact and stable, and actually one of the advance characteristics of BDD electrodes. However, the stability of the BDD surface causes the modified surface to be easily detached or dissolved after several usages. In this chapter, preparations and applications of the modified BDD for electrochemical sensors and biosensors are described and compared.

  • Introduction

    Einaga Y., Diamond Electrodes: Fundamentals and Applications, 2022.01

     View Summary

    A first example of electrochemical measurement using diamond as an electrode is a study by Iwaki et al. (RIKEN) in 1983. This is a preview of subscription content, access via your institution.

  • Industrial Application of Electrochemical Chlorine Sensor

    Einaga Y., Diamond Electrodes: Fundamentals and Applications, 2022.01

     View Summary

    Monitoring free chlorine concentration is an important issue in various situations. Residual chlorine that does not react with organic compounds, and metals dissolve in water to produce HClO (hypochlorous acid) and ClO- (hypochlorite ion). In 2008, we reported that free chlorine, which has a strong disinfecting effect, can be monitored with high sensitivity using a boron-doped diamond (BDD) electrode. However, the problem of pH fluctuation of the solution and the detailed mechanism of redox have not been completely clarified. Then, in 2016, the electrochemical redox mechanism of this free chlorine was carefully studied. Based on these results, we designed a new system using BDD electrodes that can monitor the free chlorine concentration in real time.

  • In Vivo Real-Time Measurement of Drugs

    Ogata G., Sawamura S., Asai K., Kusuhara H., Einaga Y., Hibino H., Diamond Electrodes: Fundamentals and Applications, 2022.01

     View Summary

    Drugs play a key role in the treatment of patients with various diseases. A compound, when administered systemically, shows differential spatial and temporal distribution patterns not only in the body but also within each organ. In response to an increase or decrease in local concentrations in the organ, the activity of the cell population expressing the drug’s target protein(s) changes over time. Therefore, real time, simultaneous detection of kinetics of the drug and its pharmacological effects in in vivo microenvironments is essential for evaluating the efficacy of medicines. Although such challenging dual-mode measurement has not yet been addressed by any conventional methods, it has been successfully achieved via a microsensing system that we recently developed. The system consists of two different sensors: A needle-type boron-doped diamond microelectrode for monitoring the drug and a glass microelectrode for tracking electrophysiological activity of the target cells. This state-of-the-art approach is applicable to various drugs in terms of “local” pharmacokinetic and pharmacodynamic assays in vivo and may contribute to the development of next-generation therapeutic interventions.

display all >>

Papers 【 Display / hide

  • A strategy for low-cost portable monitoring of plasma drug concentrations using a sustainable boron-doped-diamond chip

    Saiki T., Ogata G., Sawamura S., Asai K., Razvina O., Watanabe K., Kato R., Zhang Q., Akiyama K., Madhurantakam S., Ahmad N.B., Ino D., Nashimoto H., Matsumoto Y., Moriyama M., Horii A., Kondo C., Ochiai R., Kusuhara H., Saijo Y., Einaga Y., Hibino H.

    Heliyon (Heliyon)  9 ( 5 )  2023.05

    ISSN  24058440

     View Summary

    On-site monitoring of plasma drug concentrations is required for effective therapies. Recently developed handy biosensors are not yet popular owing to insufficient evaluation of accuracy on clinical samples and the necessity of complicated costly fabrication processes. Here, we approached these bottlenecks via a strategy involving engineeringly unmodified boron-doped diamond (BDD), a sustainable electrochemical material. A sensing system based on a ∼1 cm2 BDD chip, when analysing rat plasma spiked with a molecular-targeting anticancer drug, pazopanib, detected clinically relevant concentrations. The response was stable in 60 sequential measurements on the same chip. In a clinical study, data obtained with a BDD chip were consistent with liquid chromatography–mass spectrometry results. Finally, the portable system with a palm-sized sensor containing the chip analysed ∼40 μL of whole blood from dosed rats within ∼10 min. This approach with the ‘reusable’ sensor may improve point-of-monitoring systems and personalised medicine while reducing medical costs.

  • Electrochemical CO<inf>2</inf> reduction to CO facilitated by reduced boron-doped diamond

    Du J., Fiorani A., Einaga Y.

    Diamond and Related Materials (Diamond and Related Materials)  135 2023.05

    ISSN  09259635

     View Summary

    In the mechanistic investigations of electrochemical CO2 reduction reaction (eCO2RR), the undercoordinated site and oxidized metals are generally considered the most likely sources of catalytic sites. However, in the eCO2RR on boron-doped diamond (BDD) electrodes, metal centers are not available, and undercoordinated sites from boron doping did not demonstrated a favorable effect on the catalytic activity. By means of electrochemical activation, we found that when the surface of BDD electrodes is in a stable reduced state, the catalytic activity of eCO2RR for CO production is optimal. The Faradaic efficiency for CO production was increased up to 64 %, and the corresponding production rate reached 23 μmol cm−2 h−1, which was more than three times of the non-activated BDD set as comparison. This work demonstrates that the catalytic activity for eCO2RR can also originate from a reduced surface of BDD electrode.

  • Development of an Acrylamide Biosensor Using Guanine and Adenine as Biomarkers at Boron-Doped Diamond Electrodes: Integrated Molecular Docking and Experimental Studies

    Anggraini L.E., Rahmawati I., Nasution M.A.F., Jiwanti P.K., Einaga Y., Ivandini T.A.

    Bulletin of the Chemical Society of Japan (Bulletin of the Chemical Society of Japan)  96 ( 5 ) 420 - 428 2023.05

    ISSN  00092673

     View Summary

    An acrylamide biosensor was developed by utilizing purine bases, i.e. guanine and adenine, through computational and electrochemical approaches. The molecular docking simulation proved that interaction of double-stranded DNA with the purine bases has the lowest Gibbs binding free energy compared to other biomolecules with a ΔGbinding of -4.2759 kcal/mol. Meanwhile, cyclic voltammetry of both guanine and adenine in 0.1M phosphate buffer solution at pH 7.4 using a boron-doped diamond electrode showed an irreversible oxidation peak in the potential range of 0 to +1.8V (vs. Ag/AgCl), confirming that the oxidation reaction was irreversible. The current of these peaks decreased linearly with the concentration of acrylamide due to the adduct formation between the purine bases and acrylamide. The formation of acrylamide adducts between acrylamide and purine bases was confirmed by the shift of the peak wavelength of the UV spectrum from 260 to 257 nm. The use of guanine for acrylamide sensing showed a linear calibration curve in the concentration range of 0.20-1.00 μM (R2 = 0.99) with a limit of detection and limit of quantification attained at 0.11 and 0.36 μM, respectively. In the case of adenine, a linear calibration curve was observed in the concentration range of 0.14-1.00 μM (R2 = 0.99) with a limit of detection and limit of quantification of 0.10 and 0.34 μM, respectively. The developed method was successfully performed for the acrylamide determination in coffee samples and was validated by HPLC.

  • Spin Manipulation in a Metal–Organic Layer through Mechanical Exfoliation for Highly Selective CO<inf>2</inf> Photoreduction

    Wu D., Yin H.Q., Wang Z., Zhou M., Yu C., Wu J., Miao H., Yamamoto T., Zhaxi W., Huang Z., Liu L., Huang W., Zhong W., Einaga Y., Jiang J., Zhang Z.M.

    Angewandte Chemie - International Edition (Angewandte Chemie - International Edition)  62 ( 18 )  2023.04

    ISSN  14337851

     View Summary

    Spin manipulation of transition-metal catalysts has great potential in mimicking enzyme electronic structures to improve activity and/or selectivity. However, it remains a great challenge to manipulate room-temperature spin state of catalytic centers. Herein, we report a mechanical exfoliation strategy to in situ induce partial spin crossover from high-spin (s=5/2) to low-spin (s=1/2) of the ferric center. Due to spin transition of catalytic center, mixed-spin catalyst exhibits a high CO yield of 19.7 mmol g−1 with selectivity of 91.6 %, much superior to that of high-spin bulk counterpart (50 % selectivity). Density functional theory calculations reveal that low-spin 3d-orbital electronic configuration performs a key function in promoting CO2 adsorption and reducing activation barrier. Hence, the spin manipulation highlights a new insight into designing highly efficient biomimetic catalysts via optimizing spin state.

  • Development of Ofloxacin Electrochemical Sensor in Milk Sample using Boron-doped Diamond Electrode Decorated by Zinc Nanoparticles

    Jiwanti P.K., Hendri M., Wafiroh S., Einaga Y.

    Analytical and Bioanalytical Electrochemistry (Analytical and Bioanalytical Electrochemistry)  15 ( 4 ) 280 - 293 2023.04

     View Summary

    The study of Ofloxacin (OFL) electrochemical sensor on the surface of zinc modified boron-doped diamond (Zn-BDD) electrode is reported. OFL has been known as one of the fluoroquinolone antibiotics which is used in treating infectious diseases and also in animal agriculture. Despite its effectiveness, long-term consumption could promote antimicrobial resistance. Therefore, a sensitive and selective detection method is important. Meanwhile, BDD has been known for its low background current and high stability, in which, it is necessary for sensor application. Besides, Zn nanoparticles have been widely used for sensor applications due to their low toxicity and low cost. In this work, Zn-BDD electrode was prepared through electrodeposition. The S/B value and sensitivity for OFL analysis were 9.5 and 0.42 respectively on Zn-BDD, in which, it is higher compared to the use of a bare BDD electrode. The analysis in milk was possible with the recovery of 83.05% and 101.20% for BDD and Zn-BDD electrodes respectively. It is suggested that Zn-BDD electrode could be applied for OFL analysis for further real application.

display all >>

Papers, etc., Registered in KOARA 【 Display / hide

display all >>

Reviews, Commentaries, etc. 【 Display / hide

display all >>

Research Projects of Competitive Funds, etc. 【 Display / hide

  • 電解発生活性化学種の利用による新物質変換系の構築


    基盤研究(A), Principal investigator

  • 革新的sp3機能電極材料の創製


    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A) , Principal investigator

  • 光制御可能な超伝導ナノ微粒子の創製


    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Principal investigator


Courses Taught 【 Display / hide











display all >>