Electrochemical immunoassays

Immunoassays (IA) use the specific antigen antibody complexation for analyt ical purposes. Radioimmunoassays (RIA), fluorescence immunoassays (FIA) and enzyme immunoassays (EIA) are well established in clinical diagnostics. Fo r the development of hand-held devices which can be used for point of care measurements, electrochemical immunoassays are promising alternatives to ex isting immunochemical tests. Moreover, for opaque or optically dense matric es electrochemical methods are superior Potentiometric, capacitive and ampe rometric transducers have been applied for direct and indirect electrochemi cal immunoassays. However, due to their first detection, broad linear range and low detection limit, amperometric transducers are preferred. Competiti ve and noncompetitive amperometric immunoassays have been developed with od or compounds or enzymes as labels This review will give an overview of the most frequently applied principles in electrochemical immunoassays. The potential of an indirect competitive amperometric immunoassay for the determination of creatinine within nanomol ar range and the circumvention of the most serious problem in electrochemic al immunoassays, namely regeneration, will be discussed.