Biosensors having improved sample application and uses thereof

Abstract

The present invention relates to biosensors having improved sample application and measuring properties and their uses for detection, preferably, quantitative measurement, of analyte in a liquid sample. In particular, the invention provides for a biosensor having a sample application, reaction area and liquid soluble hydrophilic material facilitating the speed and uniformity of sample application, especially small volume sample application, via capillary flow. Methods for assaying analytes or enzymes using the biosensors are further provided.

1 . A biosensor for electrochemical analysis of a liquid sample, which biosensor comprises: 
 a) a base member having a proximal end and a distal end;    b) an electrode system comprising a working electrode and a counter electrode, said working and counter electrodes having conductive leads at said proximal end of said base member for connecting said electrodes to a readout device for electrochemical measurement, wherein said working electrode is positioned adjacent to said counter electrode, and there is a gap space between said working and counter electrodes,    c) a reaction area which encompasses at least a portion of said working electrode, said counter electrode and said gap space between the working electrode and counter electrode;    d) a dielectric coating positioned between said electrode system and said base member and within at least a portion of the reaction area; and    e) a test reagent in the reaction area, which test reagent is positioned over the dielectric layer,    wherein said test reagent comprises a liquid soluble hydrophilic component, and    wherein said test reagent further comprises at least one member selected from the group consisting of an electron transfer mediator, an enzyme effective to oxidize an analyte to be analyzed, and a substrate involved in a reaction catalyzed by an enzyme to be analyzed.    
   
   
       2 . The biosensor of  claim 1 , wherein the dielectric coating is non-conductive.  
   
   
       3 . The biosensor of  claim 1 , wherein the dielectric coating comprises a vinylpolyester, a polyimide, or a combination thereof.  
   
   
       4 . The biosensor of  claim 3 , wherein the hydrophilic component of the test reagent comprises polyvinylpyridine (PVP).  
   
   
       5 . The biosensor of  claim 1 , wherein the test reagent comprises an enzyme effective to oxidize an analyte to be analyzed.  
   
   
       6 . The biosensor of  claim 5 , wherein the enzyme is glucose oxidase.  
   
   
       7 . The biosensor of  claim 1 , wherein the test reagent comprises an electron transfer mediator.  
   
   
       8 . The biosensor of  claim 7 , wherein the electron transfer mediator is selected from the group consisting of ferrocene and its derivatives, osmium complex, tetrathiofulvalene, phenazine ethosulfate, benzoquinone and hexacyanoferrate.  
   
   
       9 . The biosensor of  claim 6 , wherein the test reagent further comprises an electron transfer mediator, and the electron transfer mediator is potassium ferricyanide.  
   
   
       10 . The biosensor of  claim 9 , wherein the dielectric coating comprises a vinylpolyester, a polyimide, or a combination thereof.  
   
   
       11 . The biosensor of  claim 10 , wherein the hydrophilic component comprises polyvinylpyridine.  
   
   
       12 . The biosensor of  claim 7 , which further comprises at least one reference electrode.  
   
   
       13 . The biosensor of  claim 7 , which further comprises a laminate member that covers the majority of the surface of the biosensor, including the reaction area.  
   
   
       14 . The biosensor of  claim 13 , further comprising sample application means and venting means which facilitate loading a sample into the reaction area.  
   
   
       15 . The biosensor of  claim 13 , wherein the sample application means is a sampling slot having an arcuate portion that protrudes into the reaction area to form a convex facing the reaction area.  
   
   
       16 . A method for assaying an analyte in a liquid sample containing or suspected of containing an analyte to be analyzed, which method comprises contacting the sample with the biosensor of  claim 5 , wherein the enzyme in the test reagent is an enzyme capable of oxidizing the analyte to be analyzed and thereby generating a current in at least one of the electrodes of the biosensor, 
 and detecting the current generated by oxidation of the analyte to assess the presence or amount of the analyte in the sample.    
   
   
       17 . The method of  claim 16 , wherein the analyte is glucose and the enzyme is glucose oxidase.  
   
   
       18 . The method of  claim 17 , wherein the sample is a blood sample.  
   
   
       19 . The method of  claim 17 , wherein the test reagent comprises polyvinylpyridine and an electron transfer mediator.  
   
   
       20 . The method of  claim 17 , wherein the electron transfer mediator is potassium ferricyanide.