Electrochemical immunoassay based on gold nanoparticles and reduced graphene oxide functionalized carbon ionic liquid electrode

Abstract

In this paper, a gold nanoparticle, reduced graphene oxide (R-GO) and poly(l-Arginine) composite material modified carbon ionic liquid electrode (CILE) was used as the platform for the construction of a new electrochemical carcinoembryonic antigen (CEA) immunosensor. The poly(l-Arginine)/R-GO composite film was used to modify CILE to fabricate Arg/R-GO/CILE through electropolymerization of l-Arginine on R-GO/CILE. Gold nanoparticles (AuNPs) were adsorbed on the modified electrode to immobilize the CEA antibody and to construct the immunosensor. The stepwise assembly process of the immunosensor was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). By combining the specific properties such as the biocompatibility and big surface area of AuNPs, and the excellent electron transfer ability of R-GO and the high conductivity of CILE, the synergistic effects of composite increased the amounts of CEA antibody adsorbed on the electrode surface and then resulted in the great increase of the electrochemical responses. Under the optimal conditions, differential pulse voltammetric responses of [Fe(CN)6]3−/4− were proportional to CEA concentration in the range from 0.5 to 200ngmL−1 with the detection limit as 0.03ngmL−1 (S/N=3). The proposed immunosensor showed good reproducibility, selectivity, and acceptable stability.