3.22 - A Novel Electrochemical Assay System

Abstract

This chapter presents an overview of a novel electrochemical assay system. Electrochemical Cloned Enzyme Donor ImmunoAssay (ECEDIA) integrates the CEDIA technology developed by Microgenics with the electrochemical sensor platform developed at Boehringer Mannheim. Theophylline is the analyte. Recombinant DNA technology is utilized to produce a unique homogeneous enzyme immunoassay system. The B-galactosidase enzyme has been split into two inactive fragments. Enzyme Acceptor (EA) is a large fragment containing approximately 95% of the native enzyme, the other fragment Enzyme Donor (ED). EA can spontaneously recombine with ED to form a catalytically active B-galactosidase enzyme. Theophylline has been covalently attached to the ED in a way that does not interfere with the reassociation of the enzyme fragments to form an active enzyme. Theophylline specific antibody, when bound to the Ed-theophylline conjugate, regulates the amount of enzyme formed by inhibiting the reassociation of the ED and EA fragments. Theophylline in the test sample competes for the specific anti-theophylline binding sites. The amount of enzyme which re-associates is directly proportional to the concentration of theophylline in the sample.