Test strips for detecting the presence of a reduced cofactor in a sample and methods for using the same

Abstract

Test strips and methods for their use in the detection of an analyte in a sample are provided. The subject test strips are characterized by at least including a water soluble tetrazolium salt on a surface of a positively charged substrate. In many embodiments, the water soluble tetrazolium salt is present as part of an analyte oxidizing signal producing system, which system includes one or more of the following additional components: an analyte oxidizing enzyme, e.g., an analyte dehydrogenase or an analyte oxidase; an electron transfer agent; and an enzyme cofactor. Also provided are systems and kits incorporating the subject test strips. The subject test strips, systems and kits find use in the measurement of a wide variety of analytes in a sample, such as a physiological sample, e.g., blood or a fraction thereof.

What is claimed is:  
     
         1 . A composition of matter comprising: 
 a positively charged substrate; and at least one    water soluble tetrazolium salt on at least one surface of said positively charged substrate.    
     
     
         2 . The composition according to  claim 1 , wherein said positively charged substrate is a bibulous substrate.  
     
     
         3 . The composition according to  claim 1 , wherein said positively charged substrate is a non-bibulous substrate.  
     
     
         4 . The composition according to  claim 1 , wherein said water soluble tetrazolium salt is part of an analyte oxidizing signal producing system.  
     
     
         5 . The composition according to  claim 4 , wherein said analyte oxidizing signal producing system comprises an analyte oxidase.  
     
     
         6 . The composition according to  claim 4 , wherein said analyte oxidizing signal producing system comprises an analyte dehydrogenase.  
     
     
         7 . The composition according to  claim 4 , wherein said analyte oxidizing signal producing system further comprises an electron transfer agent.  
     
     
         8 . The composition according to  claim 4 , wherein said analyte oxidizing signal producing system further comprises an enzyme cofactor.  
     
     
         9 . The composition according to  claim 4 , wherein said analyte oxidizing signal producing system is present as a reagent composition.