A label-free electrochemical immunoassay for carcinoembryonic antigen (CEA) based on gold nanoparticles (AuNPs) and nonconductive polymer film

A simple and sensitive label-free electrochemical immunoassay electrode for detection of carcinoembryonic antigen (CEA) has been developed. CEA antibody (CEAAb) was covalently attached on glutathione (GSH) monolayer-modified gold nanoparticle (AuNP) and the resulting CEAAb–AuNP bioconjugates were immobilized on Au electrode by electro-copolymerization with o-aminophenol (OAP). Electrochemical impedance spectroscopy and cyclic voltammetry studies demonstrate that the formation of CEA antibody–antigen complexes increases the electron transfer resistance of [Fe(CN)6]3−/4− redox pair at the poly-OAP/CEAAb–AuNP/Au electrode. The use of CEA antibody–AuNP bioconjugates and poly-OAP film could enhance the sensitivity and anti-nonspecific binding of the resulting immunoassay electrode. The preliminary application of poly-OAP/CEAAb–AuNP/Au electrode for detection of CEA was also evaluated.