Electrochemical biosensors for the detection of carcinoembryonic antigen with low fouling and high sensitivity based on copolymerized polydopamine and zwitterionic polymer

•A highly sensitive and low fouling electrochemical biosensor for CEA was developed.•Polydopamine and zwitterionic polymer were copolymerized on electrode surface.•The biosensor supported the quantification of CEA in human serum samples. It remains a very challenging problem for electrochemical biosensors to assay disease markers in real complex biological media on account of the severe nonspecific adsorption. Herein, a novel strategy for the construction of sensitive and antifouling biosensors capable of detecting a typical tumor marker, carcinoembryonic antigen (CEA), in complex biological media was developed through the convenient one-step copolymerization of polydopamine (PDA) and poly(sulfobetaine methacrylate) (PSBMA). In the presence of the copolymerized PDA and PSBMA, sensing probes (CEA aptamers) with thiol groups can be attached to the PDA via the Michael addition reaction, while the zwitterionic polymer PSBMA ensures antifouling capability of the sensing interface. The prepared electrochemical biosensor showed satisfying assaying performances for the detection of CEA, with a linear range of 0.01-10 pg mL−1, and a low limit of detection (LOD) down to 3.3 fg mL−1. More importantly, the existence of PSBMA in the sensing interface enabled the electrochemical biosensor to detect CEA in complex biological media with satisfying antifouling effect, indicating the feasibility of such biosensors based on copolymerized PDA and PSBMA for practical assaying of human serum samples.