Construction of Biosensing System for Glycated Albumin Using an Electron Transfer Peptide-Modified Protein Probe.

Glycated albumin (GA) is one of the proteins that replaces several sugar moieties and can be used as an indicator of diabetes mellitus. We developed a sensing system that uses GA in the early detection of diabetes mellitus. In this study, HYC acetylated (Ac-) at the N-terminals of the peptide was combined with wheat germ agglutinin (WGA) to recognize glucose moieties.

Fabrication of a cell-recognition/electron-transfer/cross-linker, peptide-immobilized electrode for the sensing of K562 cells.

We designed an electrode that has the ability to sense a target cell. This new electrode is intended for use in cell recognition via electron-transfer and cross-linker peptide immobilization. Myelopeptide-4 (MP-4:FRPRIMTP) is a marrow-origin peptide that interacts with receptors of the human leukemia cell line (K562 cells), and allows their differentiation.

Label-free cytosensing of cancer cells based on the interaction between protein and an electron-transfer carbohydrate-mimetic peptide.

We used an electron-transfer carbohydrate-mimetic peptide (YYYYC) to construct an electrochemical cytosensing system. Magnetic beads were modified with either asialofetuin (ASF) or soybean agglutinin (SBA) to evaluate the effect on cell sensing. Because SBA binds to the galactose residue that exists at the terminals of the carbohydrate chains in ASF, the target protein was accumulated on the protein magnetic beads.

Simultaneous Multiselective Spectroelectrochemical Fiber-Optic Sensor: Sensing with an Optically Transparent Electrode.

We present a spectroelectrochemical fiber-optic sensor with an optically transparent electrode. The sensor was fabricated by coating indium tin oxide (ITO) onto the surface of fiber-optic core chips using a polygonal barrel-sputtering method. The ITO-coated fiber-optic probe can be simply and cheaply mass-produced and used as a disposable probe.

Magnetic beads modified with an electron-transfer carbohydrate-mimetic peptide for sensing of a galactose-dependent protein.

For use in the voltammetric sensing of galactose-dependent proteins, we modified magnetic beads with a peptide that had both electroactive- and molecular recognition properties. The peptide consisted of a YXY sequence and behaved as an electron-transfer carbohydrate-mimetic peptide that would combine with proteins. With this tool, the protein could be detected via a label-free system.

Determination of heavy metal toxicity by using a micro-droplet hydrodynamic voltammetry for microalgal bioassay based on alkaline phosphatase.

We developed an electrochemical microalgal bioassay for the determination of heavy metal toxicity in water on the basis of the alkaline phosphatase (ALP) enzyme inhibition of Chlamydomonas reinhardtii. Five heavy metals were chosen as toxicants: Hg, Cd, Pb, Zn, and Cu. The induced ALP activity of C.

Design of carbohydrate/electron-transfer peptides for human histocytic lymphoma cell sensing.

A carbohydrate/electro-transfer peptide probe was fabricated to perform cell sensing. The probe consisted of a cello-oligosaccharide that was created by the conjugation of an electron-transfer peptide (YC) and a carbohydrate via a Schiff base. An oxidation wave due to a phenolic hydroxyl group was obtained by scanning with a glassy carbon electrode.

Development of an Attenuated Total Reflection Based Fiber-Optic Sensor for Real-time Sensing of Biofilm Formation.

A fiber-optic sensor capable of real-time monitoring of biofilm formation in water was developed. The sensor can be easily fabricated by removing the cladding of a multimode fiber optic to expose the core. The sensing action is based on the penetration of an evanescent wave through a biofilm formed on the surface of the exposed fiber core during total internal reflection.

Fabrication of micromagnetic beads with molecular recognition/electron-transfer peptides for the sensing of ovalbumin.

Electrochemical sensing of ovalbumin (OVA) was performed using magnetic beads with OVA recognition (RNRCKGTDVQAW)/electron-transfer (YYYYC) peptides. The focus of this study was to construct a highly sensitive and regenerative tool for OVA detection based on the interaction between a protein and peptide-1(RNRCKGTDVQAWYYYYC). The peptide-1 was introduced to the bead through four types of cross-linking reagents.

Electrochemical Sensing of Casein Based on the Interaction between Its Phosphate Groups and a Ruthenium(III) Complex.

A reaction to casein, along with β-lactoglobulin, is a main cause of milk allergies, and also is a useful indicator of protein in allergic analyses. In the present study, a simple casein sensor was developed based on the interaction between a phosphate group of casein and electroactive [Ru(NH3)6](3+). We evaluated the voltammetric behavior of a casein-[Ru(NH3)6](3+) complex using a glassy carbon electrode.

Sensing lymphoma cells based on a cell-penetrating/apoptosis-inducing/electron-transfer peptide probe.

To electrochemically sense lymphoma cells (U937), we fabricated a multifunctional peptide probe that consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. Electron-transfer peptides derive from cysteine residue combined with the C-terminals of four tyrosine residues (Y4). A peptide whereby Y4C is bound to the C-terminals of protegrin 1 (RGGRLCYCRRRFCVCVGR-NH2) is known to be an apoptosis-inducing agent against U937 cells, and is referred to as a peptide-1 probe.

Design of an electroactive peptide probe for sensing of a protein.

We designed a new electroactive peptide probe that has a molecular recognition function for the sensing of a protein. Ovalbumin (OVA) was the model protein, and when RNRCKGTDVQAW interacted with OVA, it conjugated with a tyrosine-rich peptide (Y4C). This peptide is electroactive, has a high degree of biocompatibility, and offers the possibility of gene expression.

Monitoring of the interaction between U937 cells and electroactive daunomycin with an arginine-rich peptide.

Daunomycin penetrates the membrane of a U937 cell, which is a human histiocyte-related lymphoma cell. Several arginine-rich peptides have also exhibited a high degree of permeability with these cells. Therefore, we attempted to improve the membrane permeability of daunomycin by coupling it with an arginine-rich peptide.

Simultaneous multiselective spectroelectrochemical fiber-optic sensor: demonstration of the concept using methylene blue and ferrocyanide.

Herein, we present a novel spectroelectrochemical fiber-optic sensor that combines electrochemistry, spectroscopy, and electrostatic adsorption in three modes of selectivity. The proposed sensor is simple and consists of a gold mesh cover on a multimode fiber optic that uses attenuated total reflection as the optical detection mode. The sensing is based on changes in the attenuation of the light that passes through the fiber-optic core accompanying the electrochemical oxidation-reduction of an analyte at the electrode.

Construction of a peptide with an electroactive daunomycin like a pendant arm to detect ovalbumin.

In this study, a peptide-1 (RNRCKGTDVQAW) constructing lysozyme was conjugated with an electroactive daunomycin in order to voltammetrically detect ovalbumin (OVA). Hetero-bifunctional cross-linking agents with four kinds of ethylene chains in differing lengths were used to bind the peptide-1 and daunomycin. After a cross-linking agent had reacted with an amino group of daunomycin, the compound was introduced into the peptide to the cysteine residue in the peptide using a pendant arm.

Voltammetric detection of ovalbumin using a peptide labeled with an electroactive compound.

For this study, a new method was developed to electrochemically detect ovalbumin via its binding with the peptide-1(RNRCKGTDVQAW) in lysozymes. The peptide that exists at the C-terminal of a lysozyme was combined with ovalbumin. When an electroactive compound was introduced to the N-terminal side of the peptide through ethylene gycolbis(sulfosuccinimidyl succinate), the labeled peptide-1 served as a probe for the detection of ovalbumin.

Construction of an electrode modified with gallium(III) for voltammetric detection of ovalbumin.

Electrodes modified with gallium(III) complexes were constructed to detect ovalbumin (OVA). For immobilization of a gallium(III)-nitrilotriacetate (NTA) complex, the electrode was first covered with collagen film. After the amino groups of the film had reacted with isothiocyanobenzyl-NTA, the gallium(III) was then able to combine with the NTA moieties.

Electrochemical sensing of concanavalin A using a non-ionic surfactant with a maltose moiety.

To electrochemically detect concanavalin A (ConA), a new method was developed using mixed micelles between a non-ionic surfactant with a maltose moiety and electroactive daunomycin. The surfactants, in which the length of the alkyl chain was different, were n-decyl-β-D-maltoside, n-dodecyl-β-D-maltoside, and n-tetradecyl-β-D-maltoside. The measurement principle was due to the micelle breakdown caused by the binding between the ConA and maltose moieties.

Electrochemical genotoxicity assay based on a SOS/umu test using hydrodynamic voltammetry in a droplet.

The SOS/umu genotoxicity assay evaluates the primary DNA damage caused by chemicals from the β-galactosidase activity of S. typhimurium. One of the weaknesses of the common umu test system based on spectrophotometric detection is that it is unable to measure samples containing a high concentration of colored dissolved organic matters, sediment, and suspended solids.

Electrochemical assay of concanavalin A-ovalbumin binding on magnetic beads.

To monitor protein-glycoprotein interactions on magnetic beads, the present study developed an electrochemical assay of the binding between concanavalin A (ConA) and ovalbumin (OVA). The system was a powerful model that could be used to evaluate cell junctions. ConA with an electroactive daunomycin was immobilized on 6 different sizes of magnetic beads (diameter: 1.

Voltammetric sensing of phosphoproteins using a gallium(III) acetylacetonate-modified carbon paste electrode.

The voltammetric detection of phosphoproteins was developed using a gallium(III) acetylacetonate-modified carbon paste electrode. Because phosphate groups of the protein interacted with the gallium(III) ion, the protein was accumulated on the electrode surface. A hexaammine ruthenium(III) ion, which combined with the functional groups, was used to monitor the interaction.

Multiplexed assay for proteins based on sequestration electrochemistry using the protein binding electroactive magnetic microbeads.

The paramagnetic microbead-based electrochemical binding assay was demonstrated for detecting two kinds of protein simultaneously. The principle of this assay is based on the sequestration electrochemistry. The protein binding electroactive magnetic microbeads which are conjugated with an electroactive compound and a ligand to bind specifically with a target protein were prepared.

Electrochemically monitoring the binding of concanavalin A and ovalbumin.

To evaluate protein-protein interactions, a new voltammetric method was developed using a protein labeled with an electroactive compound. Concanavalin A (ConA), which is a lectin, recognizes α-mannose residues. Because the ConA was to be bound to ovalbumin (OVA), which has a high-mannose sugar chain, ConA labeled with daunomycin was prepared as the probe to monitor the binding.

Binding assay for cholera toxin based on sequestration electrochemistry using lactose labeled with an electroactive compound.

A simple electrochemical binding assay for cholera toxin (CT) was developed using lactose labeled with daunomycin as an electroactive compound. The labeled lactose (LL) was determined with high sensitivity by adsorptive stripping voltammetry (AdSV). The electrochemical behaviors of LL at glassy carbon (GC), plastic formed carbon (PFC) and carbon nanotubes paste (CNTP) electrode were investigated.

Voltammetric detection of biological molecules using chopped carbon fiber.

Voltammetric detection of biological molecules was carried out using chopped carbon fibers produced from carbon fiber reinforced plastics that are biocompatible and inexpensive. Because chopped carbon fibers normally are covered with a sizing agent, they are difficult to use as an electrode. However, when the surface of a chopped carbon fiber was treated with ethanol and hydrochloric acid, it became conductive.