Enzymatic electrochemical biosensor

An electrochemical sensor strip, comprising:

• a base;
• a first electrode on the base;
• a first reagent layer on the first electrode, the first reagent layer comprising an electroactive organic molecule and an enzyme selected from the group consisting of glucose oxidase, glucose dehydrogenase, and mixtures thereof;
• a second electrode on the base;
• and
• a second reagent layer on the second electrode, the second reagent layer consisting essentially of a redox pair comprising a first soluble redox species and a second soluble redox species, the redox pair selected from the group consisting of an organotransition metal complex, a transition metal coordination complex, and mixtures thereof, and where
• the first soluble redox species is a reducible species, the second soluble redox species is an oxidizable species, and the molar ratio of the first soluble redox species to the second soluble redox species is greater than 1.2:1 prior to use of the sensor strip in an analysis.

A method of quantifying an analyte in a sample, comprising:

• contacting the sample with an electrochemical sensor strip;
• the electrochemical sensor strip comprising a first electrode and a first reagent layer on the first electrode, the first reagent layer comprising an electroactive organic molecule and an oxidoreductase capable of facilitating a redox reaction of the analyte;
• the electrochemical sensor strip also comprising a second electrode and a second reagent layer on the second electrode, the second reagent layer consisting essentially of a redox pair comprising a first soluble redox species and a second soluble redox species, the redox pair selected from the group consisting of an organotransition metal complex, a transition metal coordination complex, and mixtures thereof, where the first soluble redox species is capable of undergoing a redox reaction opposite that of the analyte;
• applying an electrical potential between the first and second electrodes;
• measuring a current passing through the first and second electrodes and the sample;
• and
• correlating the current to a concentration of the analyte, where the correlation between the current and the concentration of the analyte is substantially linear from zero to an analyte concentration of about 400 mg/dL.