Abstract: An immunoassay diagnostic kit, method, and apparatus for electrochemically determining the concentration of an analyte in a sample. A mixture is formed which includes the sample, an enzyme-acceptor polypeptide, an enzyme-donor polypeptide linked to an analyte analog (enzyme-donor polypeptide conjugate), a labeled substrate, and an antibody specific for the analyte to be measured. The analyte and the enzyme-donor polypeptide conjugate competitively bind to the antibody. When the enzyme-donor polypeptide conjugate is not bound to antibody, it will spontaneously combine with the enzyme acceptor polypeptide to form an active enzyme complex. The active enzyme hydrolyzes the labeled substrate, resulting in the generation of an electroactive label, which can then be oxidized at the surface of an electrode. A current resulting from the oxidation of the electroactive compound can be measured and correlated to the concentration of the analyte in the sample.

Abstract: A biosensor and method for determining the hematocrit level of a whole blood sample using electrochemistry. The biosensor includes working and counter electrodes. A porous membrane is impregnated with an electroactive compound and is spatially displaced from the surface of the electrodes. When a whole blood sample is applied to the porous substrate, a mixture of the electroactive compound and the blood is formed. The mixture settles on the electrodes and a potential difference is applied sufficient to oxidize or reduce the electroactive compound and generate a current. This current can be measured and correlated to hematocrit level.