Reagents and methods for detecting analytes

Abstract

A reagent for detecting an analyte comprises a flavoprotein enzyme, a mediator such as a phenothiazine mediator, at least one surfactant, a polymer and a buffer. The reagent may be used with an electrochemical test sensor that includes a plurality of electrodes.

1 . A reagent for detecting an analyte, the reagent comprising:
 a flavoprotein enzyme;   a mediator selected from the group   
     
       
         
         
             
             
         
       
     
     or a combination thereof, wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9  are the same or different, and are independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, cyclic, heterocyclic, halo, haloalkyl, carboxy, carboxyalkyl, alkoxycarbonyl, aryloxycarbonyl, aromatic keto, aliphatic keto, alkoxy, aryloxy, nitro, dialkylamino, aminoalkyl, sulfo, dihydroxyboron, and combinations thereof;
 at least one surfactant; 
 a polymer; and 
 a buffer, 
 wherein at least one of the surfactant and the buffer includes an inorganic salt, the ratio of the total inorganic salt to mediator is less than about 3:1. 
 
   
   
       2 . The reagent of  claim 1 , wherein the flavoprotein enzyme is FAD-glucose dehydrogenase. 
   
   
       3 . The reagent of  claim 1 , wherein the mediator includes 3-(2′,5′-disulfophenylimino)-3H-phenothiazine. 
   
   
       4 . The reagent of  claim 1 , wherein the surfactant includes a saccharide-based surfactant or a phosphorylcholine-based surfactant. 
   
   
       5 . The reagent of  claim 1 , wherein the polymer is a cellulose-based polymer. 
   
   
       6 . The reagent of  claim 1 , wherein the buffer includes a phosphate buffer. 
   
   
       7 . The reagent of  claim 1 , wherein the ratio of the total inorganic salt to mediator is in a ratio of less than about 2:1. 
   
   
       8 . A reagent for detecting an analyte in a fluid sample, the reagent comprising:
 FAD-glucose dehydrogenase having an activity of from about 0.1 Units/μL to about 10 Units/μL;   a 3-(2′,5′-disulfophenylimino)-3H-phenothiazine mediator having a concentration of from about 5 mM to about 120 mM;   a surfactant having a concentration of from about 0.05 wt. % to about 0.5 wt. % of the reagent;   a hydroxyethyl cellulose polymer having a concentration of from about 0.1 wt. % to about 4 wt. % of the reagent; and   a buffer,   wherein at least one of the surfactant and the buffer includes an inorganic salt, the ratio of the total inorganic salt to mediator is less than about 2:1.   
   
   
       9 . The reagent of  claim 8 , further comprising a phosphate buffer. 
   
   
       10 . The reagent of  claim 8 , wherein the surfactant is a heptanoyl-N-methylglucamide surfactant. 
   
   
       11 . The reagent of  claim 8 , wherein the reagent comprises FAD-glucose dehydrogenase having an activity of from about 0.5 Units/μL to about 2.5 Units/μL, a 3-(2′,5′-disulfophenylimino)-3H-phenothiazine mediator having a concentration of from about 30 mM to about 60 mM, a heptanoyl-N-methylglucamide surfactant having a concentration of from about 0.1 wt. % to about 0.4 wt. % of the reagent, and a hydroxyethyl cellulose polymer having a concentration of from about 0.2 wt. % to about 0.5 wt. % of the reagent. 
   
   
       12 . An electrochemical test sensor comprising:
 a working electrode having a surface;   a counter electrode having a surface; and   a reagent coating at least a portion of the surface of the working electrode and at least a portion of the surface of the counter electrode, the reagent comprising a flavoprotein, a phenothiazine or a phenoxazine mediator, a buffer, and at least one surfactant, a polymer and a buffer, wherein at least one of the surfactant and the buffer includes an inorganic salt, the ratio of the total inorganic salt to mediator is less than about 3:1.   
   
   
       13 . The sensor of  claim 12 , wherein the flavoprotein includes FAD-glucose dehydrogenase. 
   
   
       14 . The sensor of  claim 12 , wherein the phenothiazine mediator includes 3-(2′,5′-disulfophenylimino)-3H-phenothiazine. 
   
   
       15 . The sensor of  claim 12 , wherein the at least one surfactant includes a heptanoyl-N-methylglucamide. 
   
   
       16 . The sensor of  claim 12 , wherein the ratio of the total inorganic salt to mediator is in a ratio of less than about 2:1. 
   
   
       17 . A method of detecting an analyte in a fluid sample, the analyte undergoing a chemical reaction, the method comprising the acts of:
 providing an electrode surface;   facilitating flow of the fluid sample to the electrode surface using at least one surfactant;   catalyzing the chemical reaction with a flavoprotein enzyme;   generating a redox equivalent by the chemical reaction; and   transferring the redox equivalent to the electrode surface using a phenothiazine or a phenoxazine mediator,   wherein the maximum kinetic performance is less than about 3 seconds.   
   
   
       18 . The method of  claim 17 , wherein the electrode surface includes a working electrode and a counter electrode, the electrode surface including a reagent comprising the at least one surfactant, the flavoprotein enzyme, the phenothiazine mediator, and a buffer. 
   
   
       19 . The method of  claim 18 , wherein the reagent further includes a polymer. 
   
   
       20 . The method of  claim 17 , wherein the buffer includes a phosphate buffer. 
   
   
       21 . The method of  claim 17 , wherein the maximum kinetic performance is less than about 2 seconds. 
   
   
       22 . A method of detecting an analyte in a fluid sample, the method comprising the acts of:
 providing an electrode surface;   providing a reagent including a flavoprotein enzyme; a mediator selected from the group   
     
       
         
         
             
             
         
       
     
     or a combination thereof wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9  are the same or different, and are independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, cyclic, heterocyclic, halo, haloalkyl, carboxy, carboxyalkyl, alkoxycarbonyl, aryloxycarbonyl, aromatic keto, aliphatic keto, alkoxy, aryloxy, nitro, dialkylamino, aminoalkyl, sulfo, dihydroxyboron, and combinations thereof; at least one surfactant; and a buffer; the reagent being in contact with the electrode surface;
 contacting the fluid sample with the reagent; and 
 determining the concentration of the analyte, 
 wherein the maximum kinetic performance is less than about 3 seconds. 
 
   
   
       23 . The method of  claim 22  wherein the reagent further includes a polymer. 
   
   
       24 . The method of  claim 22  wherein the reagent includes a phenothiazine mediator. 
   
   
       25 . The method of  claim 22  wherein at least one of the surfactant and the buffer includes an inorganic salt, the ratio of the total inorganic salt to mediator is less than about 3:1. 
   
   
       26 . The method of  claim 25  wherein at least one of the surfactant and the buffer includes an inorganic salt, the ratio of the total inorganic salt to mediator is less than about 2:1. 
   
   
       27 . The method of  claim 22  wherein the maximum kinetic performance is less than about 2 seconds.