Bipolar electrochemical sensor with perylene diimide-based cathodic luminophore for dopamine detection and imaging.

Bipolar electrochemical microscopy (BEM), which visualizes the concentration distribution of molecular species in biological systems by electrochemiluminescence (ECL), is expected to be applied to the high-spatiotemporal-resolution imaging of biomolecules, enabling the analysis of cellular functions. In the past, the molecular species that could be imaged by BEM were generally restricted to oxidized molecules due to the limitation derived from the ECL mechanism of the luminophore. Recently, the imaging of dopamine (DA), a reduced molecule, was achieved using Ru (bpy)/glutathione disulfide (GSSG) as a cathodic luminophore.

Highly Sensitive Electrochemical Endotoxin Sensor Based on Redox Cycling Using an Interdigitated Array Electrode Device.

The amebocyte lysate (LAL) reaction-based assay, the most commonly used endotoxin detection method, requires a skilled technician. In this study, to develop an easy-to-use and highly sensitive endotoxin sensor, we created an electrochemical endotoxin sensor by using an interdigitated array electrode (IDAE) device with advantages of amplifiable signals via redox cycling and portability. We added Boc-Leu-Gly-Arg--aminophenol (LGR-pAP) as an electrochemical substrate for an LAL reaction and detected -aminophenol (pAP) released from LGR-pAP as a product of an endotoxin-induced LAL reaction via an IDAE device.

Batteryless wireless magnetostrictive FeCo/Ni clad plate for human coronavirus 229E detection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been garnered increasing for its rapid worldwide spread. Each country had implemented city-wide lockdowns and immigration regulations to prevent the spread of the infection, resulting in severe economic consequences. Materials and technologies that monitor environmental conditions and wirelessly communicate such information to people are thus gaining considerable attention as a countermeasure.

Highly Sensitive Electrochemical Immunoassay Using Signal Amplification of the Coagulation Cascade.

Here, we report a highly sensitive immunoassay for human immunoglobulin G (IgG) that uses signal amplification of the coagulation cascade. Z-Phe-Pro-Lys--nitroaniline (FPK-NA) was used as a substrate for thrombin activation in the last step of the coagulation cascade. During the coagulation cascade, NA is liberated from FPK-NA and can be detected electrochemically.

Fabrication of High-Density Vertical Closed Bipolar Electrode Arrays by Carbon Paste Filling Method for Two-Dimensional Chemical Imaging.

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.

Bioimaging using bipolar electrochemical microscopy with improved spatial resolution.

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 the pores of a track-etched membrane using electroless plating.

Anti-DNA antibodies cross-reactive with β-glycoprotein I induce monocyte tissue factor through the TLR9 pathway.

Antibodies specific for cardiolipin (CL)-β-glycoprotein I (βGPI) are known to induce tissue factor (TF) expression by monocytes and endothelial cells which leads to a prothrombotic state in antiphospholipid syndrome (APS), but the mechanism is not fully elucidated. Previously, we reported that the mouse monoclonal anti-CL-βGPI antibody WB-6 cross-reacts with DNA, enters monocytes binding to cell surface DNA, and induces TF expression. The current study aimed to identify the intracellular signaling pathways involved in this process.

Recent Advances in Electrochemiluminescence-Based Systems for Mammalian Cell Analysis.

Mammalian cell analysis is essential in the context of both fundamental studies and clinical applications. Among the various techniques available for cell analysis, electrochemiluminescence (ECL) has attracted significant attention due to its integration of both electrochemical and spectroscopic methods. In this review, we summarize recent advances in the ECL-based systems developed for mammalian cell analysis.

Real-time imaging of photosynthetic oxygen evolution from spinach using LSI-based biosensor.

The light-driven splitting of water to oxygen (O) is catalyzed by a protein-bound tetra-manganese penta-oxygen calcium (MnOCa) cluster in Photosystem II. In the current study, we used a large-scale integration (LSI)-based amperometric sensor array system, designated Bio-LSI, to perform two-dimensional imaging of light-induced O evolution from spinach leaves. The employed Bio-LSI chip consists of 400 sensor electrodes with a pitch of 250 μm for fast electrochemical imaging.

A highly sensitive endotoxin sensor based on redox cycling in a nanocavity.

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 endotoxin assay using a nanocavity device.

Electrochemical Motion Tracking of Microorganisms Using a Large-Scale-Integration-Based Amperometric Device.

Motion tracking of microorganisms is useful to investigate the effects of chemical or physical stimulation on their biological functions. Herein, we describe a novel electrochemical imaging method for motion tracking of microorganisms using a large-scale integration (LSI)-based amperometric device. The device consists of 400 electrochemical sensors with a pitch of 250 μm.

Imaging of enzyme activity using bio-LSI system enables simultaneous immunosensing of different analytes in multiple specimens.

Electrochemical imaging is an excellent technique to characterize an activity of biomaterials, such as enzymes and cells. Large scale integration-based amperometric sensor (Bio-LSI) has been developed for the simultaneous and continuous detection of the concentration distribution of redox species generated by reactions of biomolecules. In this study, the Bio-LSI system was demonstrated to be applicable for simultaneous detection of different anaytes in multiple specimens.

Programmed Cell Death Ligand 1 Expression in Canine Cancer.

Background: Antibody therapy targeting programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) is a promising therapy in human cancer, but only limited information on PD-L1 expression in canine tumors is available.

Materials And Methods: PD-L1 expression was examined in 31 canine tumor cell lines of various origins by flow cytometry and western blotting, and in canine tumor and normal tissue specimens by immunohistochemistry.

Results: PD-L1 was only expressed on the cell surface of a small number of cell lines but was found expressed within the cells of almost all cell lines.

Simultaneous Real-Time Monitoring of Oxygen Consumption and Hydrogen Peroxide Production in Cells Using Our Newly Developed Chip-Type Biosensor Device.

All living organisms bear its defense mechanism. Immune cells during invasion by foreign body undergoes phagocytosis during which monocyte and neutrophil produces reactive oxygen species (ROS). The ROS generated in animal cells are known to be involved in several diseases and ailments, when generated in excess.

Simulation Analysis of Positional Relationship between Embryoid Bodies and Sensors on an LSI-based Amperometric Device for Electrochemical Imaging of Alkaline Phosphatase Activity.

In the present study, we monitored the alkaline phosphatase (ALP) activity of embryoid bodies (EBs) of mouse embryonic stem (ES) cells using a large-scale integration (LSI)-based amperometric device with 400 sensors and a pitch of 250 μm. In addition, a simulation analysis was performed to reveal the positional relationship between the EBs and the sensor electrodes toward more precise measurements. The study shows that simulation analysis can be applied for precise electrochemical imaging of three-dimensionally cultured cells by normalization of the current signals.

Electrochemical Imaging of Dopamine Release from Three-Dimensional-Cultured PC12 Cells Using Large-Scale Integration-Based Amperometric Sensors.

In the present study, we used a large-scale integration (LSI)-based amperometric sensor array system, designated Bio-LSI, to image dopamine release from three-dimensional (3D)-cultured PC12 cells (PC12 spheroids). The Bio-LSI device consists of 400 sensor electrodes with a pitch of 250 μm for rapid electrochemical imaging of large areas. PC12 spheroids were stimulated with K(+) to release dopamine.

Electrochemical sensor with substitutional stripping voltammetry for highly sensitive endotoxin assay.

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 SSV, based on the accumulation of an amperometric signal owing to exchange of the oxidation current of pAP generated at an electrode in a reaction cell with silver deposition on another electrode in a deposition cell.

Electrochemical approach for the development of a simple method for detecting cell apoptosis based on caspase-3 activity.

This paper reports a novel approach for the simple detection of cell apoptosis using an electrochemical technique. This method uses caspase-3 activity as an indicator of apoptosis. Caspase-3 activity was detected with differential plus voltammetry (DPV) as an alternative to conventional spectrometry.

SU-8-based flexible amperometric device with IDA electrodes to regenerate redox species in small spaces.

A flexible sensor based on SU-8 photoresist was fabricated and its electrochemical performance was investigated using cyclic voltammetry. The device consisted of interdigitated array (IDA) electrodes on an SU-8 layer. It exhibited a clear electrochemical response during redox cycling of ferrocenemethanol at the IDA electrodes.

Droplet array on local redox cycling-based electrochemical (LRC-EC) chip device.

We have previously reported a local redox cycling-based electrochemical (LRC-EC) system for the incorporation of many electrochemical sensors into a small chip device. In the present study, a new type of LRC-EC chip device was fabricated for the detection of a droplet array. To detect electrochemically redox compounds in droplets, Pt pseudo-reference/counter electrodes were incorporated into the individual sensors of the LRC-EC chip device.

A screen-printed endotoxin sensor based on amperometry using a novel p-aminophenol conjugated substrate for a Limulus amebocyte lysate protease reaction.

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.