Reagents for electrochemical test strips
First Claim
1. A dry reagent composition comprising:
- (a) an active redox enzyme that oxidizes an analyte as a specific substrate to produce an inactive reduced form of the enzyme; and
(b) tris-tetramethylammonium ferricyanide.
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Abstract
A dry reagent composition that includes an active redox enzyme that oxidizes an analyte as a specific substrate to produce an inactive reduced form of the enzyme; and a salt of ferricyanide provides improved performance in electrochemical test strips such as those used for detection of glucose. The salt of ferricyanide consists of ferricyanide and positively-charged counter ions, and the positively charged counter ions are selected such that the salt of ferricyanide is soluble in water, and such that the salt of ferricyanide or the crystalline phase of the salt of ferricyanide has a solubility in water and/or a lower E0eff at a concentration of 100 mM than potassium ferricyanide. For example, the salt of ferricyanide may be tetramethylammonium ferricyanide.
40 Citations
30 Claims
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1. A dry reagent composition comprising:
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(a) an active redox enzyme that oxidizes an analyte as a specific substrate to produce an inactive reduced form of the enzyme; and (b) tris-tetramethylammonium ferricyanide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 16, 17, 18, 22, 23, 24, 25, 26, 27, 28, 29)
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13. A dry reagent composition comprising:
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(a) an active redox enzyme that oxidizes an analyte as a specific substrate to produce an inactive reduced form of the enzyme; (b) tris-tetramethylammonium ferricyanide; (c) an electron transfer mediator in oxidized form that is not a salt of ferricyanide, said oxidized form of electron transfer mediator having an electrochemical potential in aqueous medium sufficient to oxidize the inactive reduced form of the enzyme to regenerate active redox enzyme, wherein the electron transfer mediator is Os(dmbpy)2PicCl, and (d) a zwitterion buffering agent comprising a positively-charged buffer counter ion and a buffer conjugate base, wherein essentially all of the positively-charged buffer counter ion is tetramethylammonium. - View Dependent Claims (14, 15)
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19. A dry reagent composition comprising:
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an active redox enzyme that oxidizes an analyte as a specific substrate to produce an inactive reduced form of the enzyme; (b) tris-tetramethylammonium ferricyanide; and (c) a zwitterion buffering agent comprising a positively-charged buffer counter ion and a buffer conjugate base, wherein essentially all of the positively-charged buffer counter ion is tetramethylammonium. - View Dependent Claims (20, 21)
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30. A method for forming a dry shelf stable electrochemical test reagent for use in detection of an analyte comprising the steps of:
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(a) selecting an oxidoreductase enzyme that oxidizes/reduces the analyte as a specific substrate; (b) combining the selected enzyme and tris-tetramethylammonium ferricyanide to form a dry shelf stable electrochemical test reagent for use in detection of the analyte, wherein the selected enzyme is glucose oxidase.
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Specification