Determination of glycoprotein and glycosylated hemoglobin in blood
First Claim
1. An amperometric sensor for assaying the concentration of a fructosamine moiety contained in a biological fluid in the presence of interfering oxidizable substances also contained in the fluid, comprising:
- a sensing electrode, the sensing electrode comprising;
a non-conductive support member strip,with the non-conductive support member strip coated with an electrically conductive layer, with the electrically conductive layer containing;
a first redox mediator; and
a reference electrode comprising;
a non-conductive support member strip, with the support member strip coated with an electrically conductive formulation comprising Ag/AgCl dispersed in a resin formulation, and with the reference electrode having an opening; and
a reagent strip, the reagent strip comprising;
a water absorbent carrier, the water absorbent carrier impregnated with a mixture comprising;
a second redox mediator that can be reduced by a fructosamine derivative,at least one surfactant,at least one stabilizer,a buffering agent to maintain a pH from about 8 to about 12; and
a whole blood treatment component selected from the group consisting of;
an erythrocyte filtration component and an erythrocyte lysing component;
with the electrically conducting layer of the sensing electrode and the electrically conductive formulation of the reference electrode facing each other; and
with the reagent strip superimposed on and in physical contact with the electrically conducting layer of the sensing electrode, and with the whole blood treatment component superimposed on and in physical contact with the reagent strip; and
with the reference electrode superimposed on the whole blood treatment component so that the electrically conductive formulation coating the reference electrode is in physical contact with the whole blood treatment component; and
with the whole blood treatment component completely covering the opening in the reference electrode;
so that the sensing electrode and the reagent strip and the whole blood treatment component and the reference electrode form a sandwich.
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Abstract
A method of determining the concentration of glycoproteins and glycosylated hemoglobin in whole blood and whole blood components by means of an amperometric biosensor and an amperometric biosensor for this determination are provided. In one embodiment, whole blood is introduced into a version of an amperometric sensor having a component that removes erythrocytes. Redox mediators are used to obtain a current flow based on the oxidation of fructosamine derivatives that can be correlated with the concentration of glycosylated proteins in the fraction of the blood from which erythrocytes have been excluded. To obtain the concentration of glycosylated hemoglobin, whole blood is introduced into a version of the sensor which includes a component that produces lysis of the erythrocytes yielding a current flow proportional to the total quality of glycosylated proteins including glycosylated hemoglobin. The glycosyltaed hemoglobin concentration is obtained by subtracting the glycoprotein concentration in the absence of erythrocytes from the glycoprotein concentration of the lysed whole blood. The sensor generally comprises a sensing electrode having a first redox mediator dispersed in an electrically conductive medium such as an electrically conductive graphite formulation; a reference electrode such as a standard silver-silver chloride electrode; a reagent strip containing a pH buffer and a second redox mediator system in a gel medium; and a whole blood treatment component consisting of either a membrane or other means to filter erythrocytes from whole blood or a means to lyse erythrocytes. In a preferred form, that has high sensitivity, the sensing electrode and the reference electrode may be formed as coatings on separate non-conductive strips such as polyester film with these strips arranged so that they form "the bread" of a sandwich in which the electrode coatings are face-to-face and the reagent strip and the filtration or lysing component form the "filling" of the sandwich. The filtration or cell lysing component covers an opening in the reference electrode through which samples are introduced, and is superimposed on the reagent strip.
101 Citations
28 Claims
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1. An amperometric sensor for assaying the concentration of a fructosamine moiety contained in a biological fluid in the presence of interfering oxidizable substances also contained in the fluid, comprising:
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a sensing electrode, the sensing electrode comprising; a non-conductive support member strip, with the non-conductive support member strip coated with an electrically conductive layer, with the electrically conductive layer containing; a first redox mediator; and a reference electrode comprising; a non-conductive support member strip, with the support member strip coated with an electrically conductive formulation comprising Ag/AgCl dispersed in a resin formulation, and with the reference electrode having an opening; and a reagent strip, the reagent strip comprising; a water absorbent carrier, the water absorbent carrier impregnated with a mixture comprising; a second redox mediator that can be reduced by a fructosamine derivative, at least one surfactant, at least one stabilizer, a buffering agent to maintain a pH from about 8 to about 12; and a whole blood treatment component selected from the group consisting of; an erythrocyte filtration component and an erythrocyte lysing component; with the electrically conducting layer of the sensing electrode and the electrically conductive formulation of the reference electrode facing each other; and
with the reagent strip superimposed on and in physical contact with the electrically conducting layer of the sensing electrode, and with the whole blood treatment component superimposed on and in physical contact with the reagent strip; and
with the reference electrode superimposed on the whole blood treatment component so that the electrically conductive formulation coating the reference electrode is in physical contact with the whole blood treatment component; and
with the whole blood treatment component completely covering the opening in the reference electrode;
so that the sensing electrode and the reagent strip and the whole blood treatment component and the reference electrode form a sandwich. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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11. A method for the amperometric determination of the concentration of fructosamine derivatives contained in a sample of whole blood or fractions thereof, in the presence of interfering oxidizable substances also contained in the sample, comprising the steps of:
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providing an amperometric biosensor for fructosamine derivatives having high sensitivity at low applied potentials, the biosensor comprising; a sensing electrode, with the sensing electrode comprising; a non-conductive support strip, with the non-conductive support strip coated with an electrically conductive layer, with the electrically conductive layer containing a first redox mediator, and a reference electrode, with the reference electrode comprising; a non-conductive support strip, with the non-conductive support strip coated with an electrically conductive formulation comprising Ag/AgCl dispersed in a resin formulation, and with the reference electrode having an opening; and a reagent strip, with the reagent strip comprising; a water absorbent carrier, with the water absorbent carrier containing a second redox mediator comprising at least one compound that can be reduced by a fructosamine derivative, and a buffering agent to maintain a pH from about 8 to about 12; and a whole blood treatment component with the whole blood treatment component comprising; a component selected from the group consisting of an erythrocyte filtration component and an erythrocyte lysing component, with the electrically conducting layer of the sensing electrode and the electrically conductive formulation of the reference electrode facing each other; and
with the reagent strip superimposed on and in physical contact with the electrically conducting layer of the sensing electrode, and with the whole blood treatment component superimposed on and in physical contact with the reagent strip; and
with the reference electrode superimposed on the whole blood treatment component so that the electrically conductive formulation coating the reference electrode is in physical contact with the whole blood treatment component and with the whole blood treatment component completely covering the opening in the reference electrode;
so that the sensing electrode and the reagent strip and the whole blood treatment component and the reference electrode form a sandwich;contacting the whole blood treatment component of the biosensor with an aliquot of a whole blood sample and, maintaining a potential of 500 mV or less across the sensing electrode and the reference electrode and, measuring the current passing between the sensing electrode and the reference electrode and, comparing the current measured to a calibration curve of the concentration of a fructosamine versus current for the biosensor, whereby the concentration of the fructosamine is substantially precisely determined in the presence of the interfering substances. - View Dependent Claims (10, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for the amperometric determination of the concentration of glycosylated hemoglobin contained in a sample of whole blood in the presence of interfering oxidizable substances also contained in the whole blood sample comprising the steps of:
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providing a first and a second amperometric biosensor for fructosamine derivatives, with the first biosensor having a whole blood treatment component comprising an erythrocyte filtration component and the second biosensor having a whole blood treatment component comprising an erythrocyte lysing component, with each biosensor further comprising; a sensing electrode, with the sensing electrode comprising; a non-conductive support strip, with the non-conductive support strip coated with an electrically conductive layer, with the electrically conductive layer containing a first redox mediator; a reference electrode, with the reference electrode comprising; a non-conductive support strip, with the non-conductive support strip coated with an electrically conductive formulation comprising Ag and AgCl dispersed in a resin formulation, and with the reference electrode having an opening; and a reagent strip, with the reagent strip comprising; a water absorbent carrier, with the water absorbent carrier containing a second redox mediator comprising at least one compound that can be reduced by a fructosamine derivative, and a buffering agent to maintain a pH from about 8 to about 12; with the electrically conductive layer of the sensing electrode and the electrically conductive formulation of the reference electrode facing each other; and
with the reagent strip superimposed on and in physical contact with the electrically conducting layer of the sensing electrode, and with the whole blood treatment component superimposed on and in physical contact with the reagent strip; and
with the reference electrode superimposed on the whole blood treatment component so that the electrically conductive formulation coating the reference electrode is in physical contact with the whole blood treatment component and with the whole blood treatment component completely covering the opening in the reference electrode;
so that the sensing electrode and the reagent strip and the whole blood treatment component and the reference electrode form a sandwich; andintroducing an aliquot of a whole blood sample into each biosensor; and maintaining a potential of 500 mv or less across the sensing electrode and the reference electrode of each biosensor and, measuring the current passing between the sensing electrode and the reference electrode of each biosensor, and comparing the current measured for each biosensor to a calibration curve of the concentration of a fructosamine derivative versus current corresponding to each biosensor to determine the corresponding concentration of the fructosamine derivative measured by each biosensor, and subtracting the concentration of fructosamine derivative determined with the first biosensor having the erythrocyte filtration component from the concentration of fructosamine derivative determined with the second biosensor having the erythrocyte lysing component to obtain the concentration of glycosylated hemoglobin in the whole blood. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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Specification