Electrochemical immunosensor for the carcinoembryonic antigen based on a nanocomposite consisting of reduced graphene oxide, gold nanoparticles and poly(indole-6-carboxylic acid)

We describe a label-free electrochemical immunosensor for the carcinoembryonic antigen (CEA). It is based on a nanocomposite consisting of electrochemically reduced graphene oxide, gold nanoparticles (AuNPs), and poly(indole-6-carboxylic acid). Coupled to nanoparticle-amplification techniques and modified with ionic liquid (IL), this immunoassay shows high sensitivity and good selectivity for CEA. At the best working voltage of 0.95 V (vs. Ag/AgCl), the lower detection limit is 0.02 ng center dot mL(-1), and the response to CEA is linear in the range from 0.02 to 90 ng center dot mL(-1). The method was applied to the determination of CEA in spiked serum samples and gave recoveries in the range from 98.5 % to 102 %.