Kyushu University Academic Staff Educational and Research Activities Database
List of Reports
Ishimatsu Ryoichi Last modified date:2019.12.25

Assistant Professor / Molecular Information Systems / Department of Applied Chemistry / Faculty of Engineering


Reports
1. Ryoichi Ishimatsu, An analytical approach for electrogenerated chemiluminescence based on the electronic states of light emitting materials, bunseki kagaku, 10.2116/bunsekikagaku.67.661, 2018.01, Electrogenerated chemiluminescence can be seen because of radiative transitions from excited states, which are formed through homogeneous electron transfer between the electrochemically generated oxidized and reduced form of a light-emitting material. Therefore, photophysical and electrochemical properties with homogeneous electron transfer processes can affect the ECL properties. Although the ECL spectra and intensities (efficiencies) are the main concern as the ECL properties, by analyzing the ECL properties while considering the photophysical and electrochemical properties with the electronic states, it is possible to understand the ECL properties deeply. Here the ECL properties of some light-emitting molecules, such as thermally activated delayed fluorescent molecules, a borondipyrromethene derivative, and liquid fluorescent molecules, are summarized along with their electronic states. The electronic states of Ru(bpy) 3 2+ and its oxidized and reduced forms were estimated with density functional theory calculations to reveal the relationship between the electronic state and the redox behavior of the metal center and ligands. The kinetics for the formation of the lowest excited singlet and triplet states were estimated with the Marcus theory by considering the diffusion of the electrogenerated species. Moreover, simulating the ECL behavior with a coreactant, tripropylamine, based on a finite element method, was described..
2. Shigeru Amemiya, Yushin Kim, Ryoichi Ishimatsu, Benjamin Kabagambe, Electrochemical heparin sensing at liquid/liquid interfaces and polymeric membranes, Analytical and Bioanalytical Chemistry, 10.1007/s00216-010-4056-2, 2011.01, The monitoring of heparin and its derivatives in blood samples is important for the safe usage of these anticoagulants and antithrombotics in many medical procedures. Such an analytical task is, however, highly challenging due to their low therapeutic levels in the complex blood matrix, and it still relies on classical, indirect, clot-based assays. Here we review recent progress in the direct electrochemical sensing of heparin and its analogs at liquid/liquid interfaces and polymeric membranes. This progress has been made by utilizing the principle of electrochemical ion transfer at the interface between two immiscible electrolyte solutions (ITIES) to voltammetrically drive the interfacial transfer of polyanionic heparin and monitoring the resulting ionic current as a direct measure of heparin concentration. The sensitivity, selectivity, and reproducibility of the ion-transfer voltammetry of heparin are dramatically enhanced compared to those of traditional potentiometry. This voltammetric principle was successfully applied for the detection of heparin in undiluted blood samples, and was used to develop highly sensitive ion-selective electrodes based on thin polymeric membranes that are intended for analytical applications beyond heparin detection. The mechanism of heparin recognition and transfer at liquid/liquid interfaces was assessed quantitatively via sophisticated micropipet techniques, which aided the development of a powerful ionophore that can extract large heparin molecules into nonpolar organic media. Moreover, the reversible potentiometric detection of a lethal heparin-like contaminant in commercial heparin preparations was achieved through the use of a PVC membrane doped with methyltridodecylammonium chloride, which enables charge density dependent polyanion selectivity..
3. Shigeru Amemiya, Jiyeon Kim, Anahita Izadyar, Benjamin Kabagambe, Mei Shen, Ryoichi Ishimatsu, Electrochemical sensing and imaging based on ion transfer at liquid/liquid interfaces, Electrochimica Acta, 10.1016/j.electacta.2013.03.098, 2013.04, Here we review the recent applications of ion transfer (IT) at the interface between two immiscible electrolyte solutions (ITIES) for electrochemical sensing and imaging. In particular, we focus on the development and recent applications of the nanopipet-supported ITIES and double-polymer-modified electrode, which enable the dynamic electrochemical measurements of IT at nanoscopic and macroscopic ITIES, respectively. High-quality IT voltammograms are obtainable using either technique to quantitatively assess the kinetics and dynamic mechanism of IT at the ITIES. Nanopipet-supported ITIES serves as an amperometric tip for scanning electrochemical microscopy to allow for unprecedentedly high-resolution electrochemical imaging. Voltammetric ion sensing at double-polymer-modified electrodes offers high sensitivity and unique multiple-ion selectivity. The promising future applications of these dynamic approaches for bioanalysis and electrochemical imaging are also discussed..
4. S. Guo, R. Ishimatsu, K. Nakano, T. Imato, Application of Crbon Quantum Dots in Electrogenerated Chemiluminescence Sencers, J. Flow Injection Anal., 2015.12.
5. R. Liu, R. Ishimatsu, K. Nakano, and T. Imato, Optical Sensing Systems Suitable for Flow Analysis on Microchips, J. Flow Injection Anal., 2013.06.