194 results about "Electron mediator" patented technology

A biosensor comprising an electrically insulating base plate, an electrode system containing a working electrode and a counter electrode disposed on the base plate, and a reagent system comprising at least an oxidoreductase, a hydrophilic polymer and an electron mediator, wherein the reagent system further comprises a substance having a function to convert an organic product generated by direct reaction of a substrate to be measured with the oxidoreductase to another compound.

A biosensor capable of measuring the concentration of one or more specific substances in one or more sample solutions almost simultaneously is provided. The biosensor comprises a plurality of sensor units, and each of the sensor units comprises an electrode system including a working electrode and a counter electrode on an insulating base plate and a reagent system including an oxidoreductase and an electron mediator. The biosensor is so configured that sample solutions supplied to the respective sensor units reach the respective reagent systems at different times. Specifically, each of the sensor units has a controlling system between a sample supply inlet and the reagent system, and the controlling system controls the time it takes for the sample solution to reach the reagent system from the sample supply inlet.

In order to provide a biosensor with high accuracy and excellent response where plasma obtained by filtration of blood rapidly arrives at an electrode system, in a biosensor comprising: an insulating base plate; an electrode system having a working electrode and a counter electrode which are provided on the base plate; a reaction layer including at least oxidoreductase and an electron mediator; a sample solution supply pathway which includes the electrode system and the reaction layer and has an inlet and an air aperture; a sample solution supply part for introducing a sample solution, which is in position apart from the sample solution supply pathway; and a first filter which is disposed between the sample solution supply pathway and the sample solution supply part for filtering the sample solution, where the filtrate filtered with the first filter is supplied into the sample solution supply pathway due to capillary action, the direction in which the sample solution passes through the first filter and the direction in which the filtrate passes through the sample solution supply pathway are made cross at right angles.

The present invention provides a biosensor having a favorable response characteristic up to a high concentration range, a low blank response and a high storage stability. This sensor comprises an electrode system including a working electrode and a counter electrode, for forming an electrochemical measurement system by coming in contact with a supplied solution; an electrically insulating supporting member for supporting the electrode system; a first reagent layer formed on the working electrode; and a second reagent layer formed on the counter electrode, wherein the first reagent layer comprises an enzyme as the main component, and the second reagent layer comprises an electron mediator as the main component.

The present invention concerns an electrode carrying immobilized redox enzymes such that electric charge can flow between an electron mediator group to the enzyme cofactor by the use of boronic acid or a boronic acid derivative that acts as a linker moiety between the cofactor and the electron mediator group. The invention also concerns devices and systems that make use of the electrode of the invention, such as biosensors and fuel cells, the electrode being one of the components thereof.

The present invention provides a sensor that electrochemically determines cholesterol in low density lipoprotein by only one feed of a sample. The sensor has: an electrode system that is mounted on an electrically insulating base plate and includes at least a working electrode and a counter electrode; an enzyme layer formed on the base plate with the electrode system; and a reagent layer that is arranged before the enzyme layer in a sample solution supply path to the electrode system. The enzyme layer includes at least an oxidoreductase and an electron mediator. The reagent layer includes a reagent that depresses reactivity of cholesterol in lipoproteins other than the low density lipoprotein with the oxidoreductase, for example, a reagent that attaches to lipoproteins other than the low density lipoprotein to form a water-soluble complex.

A sensor system that detects a current representative of a compound in a liquid mixture features a multi or three electrode strip adapted for releasable attachment to signal readout circuitry. The strip comprises an elongated support which is preferably flat adapted for releasable attachment to the readout circuitry; a first conductor and a second and a third conductor each extend along the support and comprise means for connection to the circuitry. The circuit is formed with single-walled or multi walled nanotubes conductive traces and may be formed from multiple layers or dispersions containing, carbon nanotubes, carbon nanotubes/antimony tin oxide, carbon nanotubes/platinum, or carbon nanotubes/silver or carbon nanotubes/silver-cloride. An active electrode formed from a separate conductive carbon nanotubes layer or suitable dispersion, positioned to contact the liquid mixture and the first conductor, comprises a deposit of an enzyme capable of catalyzing a reaction involving the compound and preferably an electron mediator, capable of transferring electrons between the enzyme-catalyzed reaction and the first conductor. A reference electrode also formed from a conductive carbon nanotube layer or suitable dispersion is positioned to contact the mixture and the second conductor. The system includes circuitry adapted to provide an electrical signal representative of the current which is formed from printing conductive inks made with nano size particles such as conductive carbon or carbon/platinum or carbon/silver, or carbon nanotubes/antimony tin oxide to form a conductive carbon nanotube layers. The multiple-electrode strip is manufactured, by then applying the enzyme and preferably the mediator onto the electrode. Alternatively the electrode can have a carbon nanotubes/antimony tin oxide, carbon nanotubes/platinum, or carbon nanotubes/silver or carbon nanotubes/silver-cloride surface and or a conductive carbon or silver ink surface connecting leg. The carbon nanotube solution is first coated and patterned into electro shapes and the conductive carbon nanotubes, carbon or silver ink can be attached by printing the ink to interface with the carbon nanotube electro surface. A platinum electrode test strip is also disclosed that is formed from either nano platinum distributed in the carbon nanotube layer or by application or incorporation of platinum to the carbon nanotube conductive ink.

The present invention concerns an electrode carrying immobilized redox enzymes such that electric charge can flow between an electron mediator group to the enzyme cofactor by the use of boronic acid or a boronic acid derivative that acts as a linker moiety between the cofactor and the electron mediator group. The invention also concerns devices and systems that make use of the electrode of the invention, such as bio-sensors and fuel cells, the electrode being one of the components thereof.

The present invention relates to a glucose sensor (2) including an electrode (32) which includes a conductive component and glucose dehydrogenase immobilized to the conductive component. As the glucose dehydrogenase, use is made of a protein complex including a catalytic activity subunit which has glucose dehydrogenase activity, and an electron mediator subunit for supplying an electron donated from the catalytic activity subunit to the conductive component. Preferably, the glucose sensor (2) is designed to continuously measure the glucose level or successively measure the glucose level a plurality of times.

In order to provide a cholesterol sensor capable of measuring whole blood with high accuracy and excellent response, where plasma with hemocytes therein filtered promptly reaches an electrode system, in a biosensor comprising: an insulating base plate; an electrode system which is provided on the base plate and has a measurement electrode and a counter electrode; a reaction layer including at least oxidoreductase and an electron mediator; a sample solution supply pathway which includes the electrode system and the reaction layer and has an air aperture on the termination side thereof; a sample supply portion; and a filter which is disposed between the sample solution supply pathway and the sample supply portion and filters hemocytes, where plasma with the hemocytes therein filtered with the filter is sucked into the sample solution supply pathway due to capillarity, the central part of a secondary side portion of the filter is protruded into the sample solution supply pathway more than both the right and left ends thereof.

Power generation is performed by immobilizing an electron mediator having a standard electrode potential (E₀′) at pH 7 in the range of −0.13 V to −0.28 V to one of a pair of electrodes to form an anode 1 and electrically connecting the other electrode as a cathode 3 to the anode 1 to form a closed circuit, bringing the anode 1 into contact with microorganisms capable of growing under anaerobic conditions and a solution or suspension 4 containing an organic substance to advance the oxidation reaction by microorganisms using the organic substance as an electron donor, separating the cathode 3 and the solution or suspension through an electrolyte membrane 2 to advance the reduction reaction using oxygen as an electron acceptor at the cathode, and accelerating the oxidation reaction in the biological system.

The present invention provides a so improved biosensor that a whole blood is allowed to be an object to be measured, and that plasma of a blood, with hemocytes thereof having been filtered out, is allowed to quickly reach an electrode system. This sensor comprises: an insulating base plate; an electrode system, provided on the base plate, having a measuring electrode and a counter electrode; a reaction layer comprising at least an oxidoreductase and an electron mediator; a sample solution supply pathway including the electrode system and the reaction layer; and a sample supply unit, wherein the sensor is so structured that, between the sample supply unit and the sample solution supply pathway, there is provided a filter having a function to filter out hemocytes and having a cross-sectional area larger than an opening of the sample solution supply pathway, and that plasma of a blood with hemocytes thereof having been filtered out is sucked into inside of the sample solution supply pathway owing to capillary phenomena.

The present invention relates to an enzyme electrode useful for estimation of cholesterol in aqueous medium, said electrode comprising: i. an electrically conductive base plate, ii. a film of sol gel derived material deposited thereon, said sol gel derived material of step b) being microencapsulated cholesterol oxidase with an electron mediator. The present invention also relates to a process for the preparation of an enzyme electrode by coating an immobilized cholesterol oxidase (ChOx) and mediator on a silicate sol gel by microencapsulation.

The present invention provides a biosensor that enables highly-accurate measurement of a sample solution including a solid component like hemocytes and has a little variation in response. The biosensor includes: an insulating base plate, an electrode system having at least a working electrode and a counter electrode provided on the base plate, a cover member that is combined with the base plate to define a sample solution supply pathway for leading a sample solution from a sample supply unit to the electrode system, a reaction reagent system including at least an oxidation-reduction enzyme and an electron mediator, and a filter disposed between the electrode system and the sample supply unit in the sample solution supply pathway. The biosensor has a space that encircles surface of the filter in an area from one end of the filter close to the sample supply unit to the other end of the filter close to the electrode system. This arrangement effectively prevents the solid component like hemocytes from flowing into the electrode system without being filtered out by the filter.

The invention relates to a chitosan-silica sol-gel sensitive membrane for electrochemical biosensors and a preparation method thereof, and the sensitive membrane is covalently bonded with bioactive substances and doped with electron carriers and electron mediators. By means of the sol-gel process of silane coupling agent and the covalent coupling of the silane coupling agent, the bioactive substances and chitosan, the bioactive substances are covalently bonded with a synchronously formed chitosan-silica sol-gel three-dimensional mesh structure. Meanwhile, the electron carriers and the electron mediators are doped in the chitosan-silica sol-gel three-dimensional mesh structure. Compared with the prior art, the sensitive membrane for electrochemical biosensors, which is provided by the invention, can remarkably enhance the stability, selectivity and sensitivity of the sensors.

The present invention relates to an analytical instrument (1) which includes a flow path (5) for moving a sample containing blood cells, an introduction port (50) for introducing the sample into the flow path (5), a reagent portion (51) arranged in the flow path (5), and an electron detection medium (52) for obtaining information necessary for analyzing an analysis target component contained in the sample in relation with an amount of electrons transferred. The reagent portion (51) contains an electron mediator for supplying an electron taken from the analysis target component in the sample to the electron detection medium (52), and at least part of the reagent portion is positioned adjacent to the introduction port (50).

There is provided a method for precisely quantitating a substrate by means of a measurement system with a simple structure without occurrence of a measurement error due to an interfering substance. In a method for quantitating a substrate in a sample solution which contains a dissolved interfering substance and the substrate, by the use of an electrode system and a reagent system, (a) a sample solution which contains a dissolved interfering substance and a substrate is supplied to an electrode system comprising a working electrode and a counter electrode under the existence of a reagent system comprising oxidoreductase and an electron mediator; (b) an AC potential is applied to the working electrode, to cause a redox reaction of the electron mediator: (c) an electric signal produced on the basis of the redox reaction is measured by means of the electrode system; and (d) the substrate is quantitated on the basis of the electric signal.

Disposable test strips and a wet chemistry method for measuring each of beta-hydroxybutyrate alone, combined beta-hydroxybutyrate and acetoacetate or total ketone bodies (i.e., beta-hydroxybutyrate, acetoacetate and acetone) in human bodily fluid samples, including but not limited to urine, saliva or sweat are described. The test strips need only be dipped in the sample and can be used by anyone in almost any milieu. Measurement can be made electrochemically, spectrophotometrically, fluorometrically or by comparision to a color standard. Combined acetoacetate and beta-hydroxybutyrate which account for 97-98% of total ketone bodies and may be measured in a cyclic reaction that occurs at pH about 7.0 to about 8.3 with beta-hydroxybutyrate dehydrogenase, (beta-HBD), nicotinamide adenine dinucleotide, a tetrazolium dye precursor and an electron mediator. Using this reaction, false positive results obtained from urine samples taken from patients on sulfhydryl drugs are avoided. beta-HBD from some sources was found to cause false negative results in samples (e.g. urine) containing high chloride content due to chloride inhibition of beta-HBD. Using a simple test for chloride inhibition, it was found that beta-HBD from Alcaligenes is not so inhibited. Using either beta-HBD that is not inhibited by chloride or using 10-20 times the normal concentration of this enzyme eliminates false negatives in samples having substantial chloride content, such as urine, both in the reaction described above and in other reactions disclosed for measuring each of beta-hydroxybutyrate alone, combined beta-hydroxybutyrate and acetoacetate and total ketone bodies, all of which reactions occur in the pH range of about 8.6 to about 9.5.

An object of the present invention is to provide a highly functional mediator capable of smoothly proceeding electron transfer between an electrode and a biocatalyst based on the premise that the mediator excels in safety and cost and to provide an electrode and a cell with sufficient amount of such a mediator molecule immobilized efficiently and strongly. The present invention provides a mediator mediating electron transfer between an enzyme and an electrode and containing a quinone molecule derivative, in particular, a mediator containing a VK₃ derivative. In addition, the present invention provides an electrode and a biofuel cell to which those mediators are applied.

In a biosensor comprising an insulating base plate, an electrode system including a measuring electrode and a counter electrode provided on said base plate, a cover for covering said insulating base plate, at least one reaction layer containing oxidoreductase and/or an electron mediator, a sample solution supply pathway including said electrode system and said reaction layer and communicating with an air aperture at a terminal end side, a sample solution supply part and a filter provided between said sample solution supply pathway and said sample solution supply part to filter hemocytes, an end face and a top face of a primary portion of the filter are exposed and the sample solution supply part is provided adjacently to the primary side portion so as to provide an improved biosensor which allows easy addition of whole blood to the sensor and rapid supply of the added whole blood to a filter even in the case of collecting blood by fingertip centesis for measurement.

The problem to be resolved is to provide an electron mediator and a fusion body with high affinity with an enzyme, a measuring method using extracellular secretion type cytochrome and an enzyme, an electrode, and a sensor.

The present invention relates to an electron mediator for glucose oxidoreductase comprising extracellular secretion type cytochrome, a fusion body in which the electron mediator is fused with glucose oxidoreductase, a composition for glucose measurement including the electron mediator or fusion body, a gene encoding a new extracellular secretion type cytochrome, and a measurement method using extracellular secretion type cytochrome and an enzyme, an electrode, and a sensor.

A fusion protein of pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) and a cytochrome is disclosed. PQQGDH is, for example, a water-soluble PQQGDH derived from Acinetobacter calcoaceticus. The cytochrome is, for example, an electron transfer domain of quinohemoprotein ethanol dehydrogenase from Comamonas testosteroni. The fusion protein of the present invention shows intramolecular electron transfer from PQQ, a redox center, to the cytochrome, which allow construction of a direct electron transfer-type glucose sensor which requires no electron mediators.