Kumi Y. Inoue

We have developed an LSI-based amperometric sensor called "Bio-LSI" with 400 measurement points as a platform for electrochemical bio-imaging and multi-point biosensing. The system is comprised of a 10.4 mm × 10.4 mm CMOS sensor chip with 20 × 20 unit cells, an external circuit box, a control unit for data acquisition, and a DC power box. Each unit cell of the chip contains an operational amplifier with a switched-capacitor type I-V converter for in-pixel signal amplification. We successfully re

We have developed a zymogen-based electrochemical sensor. Zymogen is an inactive enzyme precursor (proenzyme) and it is necessary to transform it biochemically (e.g., by hydrolysis and conformational change) to make it an active enzyme. In this study, we demonstrated the detection of endotoxin by using recombinant Factor C (rFC), which is a protease zymogen activated by endotoxin binding. The activated rFC hydrolyzes a synthetic substrate of Boc-Val-Pro-Arg-p-nitroanilnide to generate an electro

We have developed a large-scale integrated (LSI) complementary metal-oxide semiconductor (CMOS)-based amperometric sensor array system called "Bio-LSI" as a platform for electrochemical bio-imaging and multi-point biosensing with 400 measurement points. In this study, we newly developed a Bio-LSI chip with a light-shield structure and a mode-selectable function with the aim of extending the application range of Bio-LSI. The light shield created by the top metal layer of the LSI chip significantl

Here, we report the development of an electrochemical detection method for endotoxin based on the Limulus amebocyte lysate (LAL) assay. A mixture of LAL reagent and endotoxin sample solution was incubated for 1 h. The endotoxin activated a cascade reaction of zymogens contained in the LAL to generate p-nitroaniline (pNA) which was then electrochemically detected by differential pulse voltammetry (DPV). The generated pNA gave a clear peak at -0.75 V vs. silver/silver chloride (Ag/AgCl), which inc

In this study, we developed bipolar electrochemical microscopy (BEM) using a closed bipolar electrode (cBPE) array with an electrochemiluminescence (ECL) detecting system. Because cBPEs are not directly connected to a detector, high spatio-temporal resolution imaging can be achieved by fabricating a microelectrode array in which each electrode point is arranged in a short interval. A cBPE array with individual cBPEs arranged in 41 μm intervals was successfully fabricated by depositing gold in th

We developed a novel protease detection method based on amperometry using a p-aminophenol (pAP) conjugated substrate. We prepared Boc-Leu-Gly-Arg-pAP (LGR-pAP) as a novel substrate for a clotting enzyme, which is a protease activated by an endotoxin-induced Limulus amebocyte lysate (LAL) cascade reaction. The basic study using cyclic voltammetry revealed that the oxidation peak potentials of LGR-pAP and pAP were sufficiently separated from each other (0.25 V) to conduct amperometric detection of

Abstract A 2D imaging system using closed bipolar electrodes (cBPEs) and electrochemiluminescence (ECL) is expected to realize high spatio‐temporal resolution imaging. However, imaging of the distributions of molecules that cause an oxidation reaction on the electrode surface was not achieved by the cBPE/ECL system because the conventionally used luminophore can generate ECL only by an oxidation reaction. In this paper, we propose to implement a cathodic luminophore, [Ru(bpy) 3 ]Cl 2 /glutathion

We developed a cell-based assay device for the detection of endotoxin, the potentially toxic compound that induces septic shock. Genetically-engineered cells that secrete alkaline phosphatase (SEAP) on exposure to endotoxin were cultured in an electrochemical cell device in medium containing p-aminophenyl phosphate and various concentrations of endotoxin. After 24 hr incubation, p-aminophenol (pAP), generated by SEAP-catalyzed hydrolysis, was detected by amperometry at +0.35 V. The amperometric

We recently reported that combining positive and negative magnetostrictive plates [iron-cobalt (Fe–Co) alloy and nickel (Ni) (i.e. Fe–Co/Ni) clad plates] yields remarkable energy-harvesting and mass sensor performances. Therefore, in this study, cobalt ferrite (CoFe 2 O 4 ), which has higher negative magnetostrictive properties than Ni, was spattered onto a Fe–Co alloy plate. The CoFe 2 O 4 -spattered Fe–Co alloy plate provided higher energy-harvesting and mass sensor performances than the Fe–Co

Abstract Imaging systems using closed bipolar electrode (cBPE) arrays and electrochemiluminescence (ECL) have attracted great attention in recent years as a 2D imaging platform with high spatiotemporal resolution. However, the fabrication techniques for cBPE arrays involve complicated procedures. Therefore, a new fabrication scheme enabling the mass production of cBPE arrays with high precision, reproducibility, and yield, is desired. Here, the use of a versatile and scalable thermal drawing pro

In this study, a carbon paste filling method was proposed as a simple strategy for fabricating high-density bipolar electrode (BPE) arrays for bipolar electrochemical microscopy (BEM). High spatiotemporal resolution imaging was achieved using the fabricated BPE array. BEM, which is an emerging microscopic system in recent years, achieves label-free and high spatiotemporal resolution imaging of molecular distributions using high-density BPE arrays and electrochemiluminescence (ECL) signals. We de

We report a highly sensitive and rapid electrochemical method for the detection of endotoxin, based on a Limulus amebocyte lysate (LAL) assay using redox cycling at a pair of electrodes in a nanocavity for electrochemical signal amplification. We have previously developed Boc-Leu-Gly-Arg-p-aminophenol (LGR-pAP) as a substrate for the amperometric LAL assay, and in this work, Z-Leu-Gly-Arg-aminomethylferrocene (LGR-AMF) was newly prepared. They were examined as substrates for a LAL-based endotoxi

We have developed a novel method for detection of endotoxin with extra-high sensitivity by using substitutional stripping voltammetry (SSV). In this method, a p-aminophenol (pAP) conjugated peptide (Boc-Leu-Gly-Arg-pAP; LGR-pAP) was used as a substrate for a protease, which is activated at the last step of the endotoxin-induced Limulus amebocyte lysate (LAL) cascade reaction. Extra-highly sensitive detection of pAP liberated by the endotoxin-induced LAL reaction was successfully realized with SS