A sandwich-format electrochemical immunosensor for simultaneous determination of three cancer biomarkers using the carbon-gold nanocomposite (CGN) as immunoprobes was introduced. The CGN were fabricated through a simple microwave-assisted carbonization of glucose and deposition of gold nanoparticles (AuNPs). This nanocomposite showed great adsorption ability to the redox probes such as some organic dyes and metal ions, due to the abundant reactive oxygen functional groups on its surface. The AuNPs decorated on the nanocomposite provided extra binding sites for the three antibodies carcinoembryonic antigen (CEA), prostate specific antigen (PSA), α-fetoprotein (AFP), respectively. The ionic liquid reduced graphene oxide was combined with poly(sodium-p-styrenesulfonate) as substrate to attach the three different antibodies through electrostatic adsorption. Three separate signals can be detected directly in a single run through square wave voltammetry. Under optimized conditions, the electrochemical immunosensor exhibited good sensitivity and selectivity for the simultaneous determination of CEA, PSA and AFP with linear ranges of 0.01-100 ng mL(-1). The detection limit for CEA, PSA and AFP is 2.7, 4.8 and 3.1 pg mL(-1), respectively. This method was applied for the analysis of CEA, PSA and AFP levels in clinical serum samples, and the results were in good agreement with those of enzyme linked immunosorbent assay (ELISA). This approach gives a promising simple and sensitive immunoassay strategy for the identification and validation of specific early cancer.
Keywords: Cancer; Carbon–gold nanocomposite; Electrochemical immunosensor; Multiplexed electrochemical detection; Tumor marker.
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