Conductive sensors and their use in diagnostic assays
First Claim
1. A conductive sensor for assaying a test sample for the presence or concentration of glucose, said conductive sensor comprising:
- a) a semipermeable membrane capable of effectively separating cellular material and interfering components from a test sample and capable of allowing glucose to permeate through the semipermeable membrane at a uniform rate said semipermeable membrane having a diffusion constant for glucose in the range of from about 1×
10-9 cm2 /sec to about 5×
10-8 cm2 /sec and a diffusion constant for molecular oxygen in the range of from about 5×
10-7 cm2 /sec to about 5×
10-6 cm2 /sec and having a thickness of from about 3μ
to about 15μ
;
b) a layer of a host matrix in contact with the semipermeable membrane and permeable to the glucose, said hose matrix layer having homogeneously incorporated therein glucose oxidase, a compound having peroxidase activity and a dopant compound precursor, wherein the glucose, the glucose oxidase, the compound having peroxidase activity and the dopant compound precursor interact to form a dopant compound;
c) a layer of a polymer in its reduced form which demonstrates an increase in electrical conductivity when it is converted to its oxidized form in contact with the host matrix layer such that at least a portion of the dopant compound generated in the host matrix layer migrates to and oxidatively dopes the polymer layer to thereby increase the conductivity of this layer; and
d) means operatively connected to the polymer layer for measuring a change in conductivity of polymer layer.
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Abstract
A conductive sensor and its use in a diagnostic assay are disclosed. The miniaturized conductive sensor, utilizing a conducting polymer, is used in a diagnostic device to determine the presence or concentration of a predetermined analyte in a liquid test sample, wherein the predetermined analyte, like glucose, is assayed by an oxidase interaction. The interaction between the oxidase and a small amount of the predetermined analyte in the test sample generates, either directly or indirectly, a dopant compound in a reaction zone of the conductive sensor. The dopant compound then migrates to the detection zone of the conductive sensor of the diagnostic device to oxidize the conducting polymer and convert the conducting polymer from an insulating form to a conducting form. The resulting increase in conductivity of the conducting polymer is measured, then the conductivity increase is correlated to the concentration of the predetermined analyte in the test sample.
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Citations
21 Claims
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1. A conductive sensor for assaying a test sample for the presence or concentration of glucose, said conductive sensor comprising:
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a) a semipermeable membrane capable of effectively separating cellular material and interfering components from a test sample and capable of allowing glucose to permeate through the semipermeable membrane at a uniform rate said semipermeable membrane having a diffusion constant for glucose in the range of from about 1×
10-9 cm2 /sec to about 5×
10-8 cm2 /sec and a diffusion constant for molecular oxygen in the range of from about 5×
10-7 cm2 /sec to about 5×
10-6 cm2 /sec and having a thickness of from about 3μ
to about 15μ
;b) a layer of a host matrix in contact with the semipermeable membrane and permeable to the glucose, said hose matrix layer having homogeneously incorporated therein glucose oxidase, a compound having peroxidase activity and a dopant compound precursor, wherein the glucose, the glucose oxidase, the compound having peroxidase activity and the dopant compound precursor interact to form a dopant compound; c) a layer of a polymer in its reduced form which demonstrates an increase in electrical conductivity when it is converted to its oxidized form in contact with the host matrix layer such that at least a portion of the dopant compound generated in the host matrix layer migrates to and oxidatively dopes the polymer layer to thereby increase the conductivity of this layer; and d) means operatively connected to the polymer layer for measuring a change in conductivity of polymer layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A conductive sensor for assaying a biological fluid for the presence or concentration of a predetermined analyte, said predetermined analyte capable of interacting with an oxidase enzyme, and said conductive sensor comprising:
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a) an elastomer-based semipermeable membrane having a thickness of from about 5μ
to about 10μ
, said elastomer-based semipermeable membrane capable of effectively separating cellular material and interfering components from a biological fluid and capable of allowing a predetermined analyte to permeate through the elastomer-based semipermeable membrane at a uniform rate;b) a layer of a host matrix, comprising gelatin, chitosan or a combination thereof and having a thickness of from about 0.2μ
to about 5μ
, in contact with the semipermeable membrane, said host matrix layer permeable to the predetermined analyte and said host matrix layer having homogeneously incorporated therein an oxidase enzyme capable of interacting with the predetermined analyte, a peroxidase enzyme or a molybdenum(VI) transition metal catalyst, and iodide ion, wherein the predetermined analyte, the oxidase enzyme, the peroxidase enzyme or the molybdenum(VI) catalyst, and the iodide ion interact to generate molecular iodine;c) a layer of a conducting polymer having a thickness of from about 100 Å
to about 2000 Å
in contact with the host matrix layer such that at least a portion of the molecular iodine generated in the host matrix layer migrates to and oxidatively dopes the conducting polymer layer; andd) a microelectrode assembly in contact with the conducting polymer layer, said microelectrode assembly adapted to sense a change in conductivity of the conducting polymer layer in response to the oxidative doping of the conducting polymer layer by the molecular iodine.
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Specification