ABSTRACT
The catalytic activity of the enzyme used as label is conventionally detected either spectrophotometrically or fluorimetrically. There has been considerable interest in the development of electrochemical biosensors for immunoassays. Electrochemical biosensors can be either potentiometric or amperometric devices. A number of heterogeneous enzyme immunoassays with electrochemical detection have been developed. A number of enzymes are currently used as labels for heterogeneous and homogeneous enzyme-linked immunoassays. The reduction in the rate of enzyme catalysis occurring when the antibody binds to an enzyme-labeled antigen has led to the development of immunoassays involving the amperometric measurement of nicotinamide adenine dinucleotide. The binding of antibody molecules to the labeled denatured apoenzyme prevents reconstitution and binding of flavine-adenine dinucleotide. Enzyme inhibitors have also been used in the development of homogeneous enzyme-linked immunoassays. The detection limits for early enzyme immunoassays with electrochemical measurements were quite high.
