Test Sensors and Methods of Using The Same

Abstract

A reagent composition containing GDH-PQQ as an enzyme-co-factor and screen-printed on working and counter electrodes of electrochemical biosensors, maintains activity of the enzyme reagents by proper selection of components. A preferred composition includes hydrophilic polymers, amorphous untreated silica, buffers, surfactants, and a mediator.

1 - 17 . (canceled) 
     
     
         18 . An electrochemical biosensor comprising:
 (a) a non porous substrate;   (b) at least two electrodes disposed on said substrate; and   (c) a reagent composition deposited on said at least two electrodes, said composition comprising:
 (1) about 1-8 units of glucose dehydrogenase (GDH) and co-factor pyrrolo-quinoline quinone (PQQ), for each milligram of the total weight of said composition; 
 (2) a hydrophilic polymer selected from the group consisting of cellulose derivatives, natural gums and gels, and water soluble synthetic polymers; 
 (3) a thickening agent selected from the group consisting of amorphous untreated silica powder, talc, mica, diatomaceous earth, and natural and modified clays; 
 (4) a buffer sufficient to maintain pH in the range of from about 4.5 to about 6.5; 
 (5) a surfactant; and 
 (6) a mediator. 
   
     
     
         19 . The electrochemical biosensor of  claim 18 , wherein said buffer is about 30 to about 200mM of an acetate, citrate, or succinate buffer. 
     
     
         20 . The electrochemical biosensor of  claim 18 , wherein said surfactant is up to about 0.5 wt. % of an alkyl aryl polyether alcohol, based on the total weight of said composition. 
     
     
         21 . The electrochemical biosensor of  claim 18 , wherein said mediator is about 10 to about 20 wt % of potassium ferricyanide, based on the total weight of said composition. 
     
     
         22 - 23 . (canceled) 
     
     
         24 . The electrochemical biosensor of  claim 18 , wherein said hydrophilic polymer is about 2 to about 10 wt % of a cellulose derivative selected from the group consisting of sodium carboxy methyl cellulose, hydroxy ethyl cellulose, hydroxy propyl cellulose, and hydroxy propyl methyl cellulose, based on the total weight of said composition. 
     
     
         25 . (canceled) 
     
     
         26 . The electrochemical biosensor of  claim 18 , wherein said thickening agent is from about 1 to about 6 wt % of an amorphous untreated silica powder, based on the total weight of said composition. 
     
     
         27 - 32 . (canceled) 
     
     
         33 . The electrochemical biosensor of  claim 18 , wherein the bias associated therewith is within ±10%. 
     
     
         34 . The electrochemical biosensor of  claim 18 , wherein the bias associated therewith is within ±5% for samples having ≦400 mg/dL glucose. 
     
     
         35 . A biosensor comprising:
 a substrate;   at least two electrodes disposed on said substrate;   a reagent composition deposited on the at least two electrodes, said composition comprising:
 (a) glucose dehydrogenase (GDH) and co-factor pyrrolo-quinoline quinone (PQQ); 
 (b) 2 to about 10 wt% of a hydrophilic polymer selected from cellulose derivatives, based on the total weight of the composition; 
 (c) a buffer sufficient to maintain pH in the range of from about 4.5 to about 6.5; 
 (d) a surfactant; and 
 (e) a mediator. 
   
     
     
         36 . The biosensor of  claim 35 , wherein said buffer is an acetate, citrate, or succinate buffer. 
     
     
         37 . The biosensor of  claim 35 , wherein said surfactant is an alkyl aryl polyether alcohol. 
     
     
         38 . The biosensor of  claim 35 , wherein said mediator is potassium ferricyanide. 
     
     
         39 . The biosensor of  claim 35 , wherein the pH of the buffer ranges from 5.0 to 6.0. 
     
     
         40 . The biosensor of  claim 35 , wherein said hydrophilic polymer is a cellulose derivative selected from the group consisting of sodium carboxymethyl cellulose, hydroxy ethyl cellulose, hydroxy propyl cellulose, and hydroxy propylmethyl cellulose. 
     
     
         41 . The biosensor of  claim 35 , wherein the reagent composition further comprises about 1 to about 6 wt % of amorphous untreated silica powder, based on the total weight of the composition. 
     
     
         42 . The biosensor of  claim 35 , wherein the bias associated therewith is within ±10%. 
     
     
         43 . The reagent composition of  claim 35 , wherein the bias associated therewith is within ±5% for samples having 400 mg/dL glucose. 
     
     
         44 . A biosensor comprising:
 a substrate;   at least two electrodes disposed on said substrate;   a reagent composition deposited on the at least two electrodes, said composition comprising:
 (a) an enzyme; 
 (b) 2 to about 10 wt % of a hydrophilic polymer selected from cellulose derivatives, based on the total weight of the composition; 
 (c) a buffer sufficient to maintain pH in the range of from about 4.5 to about 6.5; 
 (e) a surfactant; and 
 (f) a mediator. 
   
     
     
         45 . The biosensor of  claim 44 , wherein the bias associated therewith is within ±10%. 
     
     
         46 . The biosensor of  claim 44 , wherein the bias associated therewith is within ±5% for samples having ≦400 mg/dL glucose. 
     
     
         47 . The biosensor of  claim 44 , wherein the reagent composition further comprises about 1 to about 6 wt % of a thickening agent selected from the group consisting of amorphous untreated silica powder, talc, mica, diatomaceous earth, and natural and modified clays, based on the total weight of the composition.