Coupling of immunoassays with enzymatic recycling electrodes

Enzymatic substrate regeneration is a tool to enhance the sensitivity of en zyme electrodes both for substrate analysis and immunoassays. The combinati on of immunoreactions and electrode based substrate recycling connects spec ific recognition of an analyte with highly sensitive detection. Most import ant for this field of application is the sensitivity, which permits to dete ct a label at very low concentration. Enzymatic substrate regenerating syst ems are reviewed which are based on sensors using acceptor dependent dehydr ogenases in combination with phenol oxidases and the lactate oxidase/lactat e dehydrogenase couple and applied as sensitive label detectors in electroc hemical immunoassays. Label compounds are either redox-active dyes or enzym es. The label enzymes measured so far are alkaline phosphatase and beta -ga lactosidase.