Label-free photoelectrochemical immunosensing platform for detection of carcinoembryonic antigen through photoactive conducting poly(5-formylindole) nanocomposite

Poly(5-formylindole)/electrochemically reduced graphene oxide (P5FIn/erGO) nanocomposite is firstly used to construct a label-free photoelectrochemical (PEC) immunosensor to detect carcinoembryonic antigen (CEA). As photoactive material and electroactive mediator, the prepared P5FIn/erGO nanocomposite exhibits high photocurrent intensity under visible-light irradiation due to the synergistic effect of P5FIn and erGO. The anti-CEA is connected to the P5FIn/erGO modified electrode surface, and gold nanoparticles (AuNP) is used as cross-linking in the process. The linear decrease of photocurrent is caused by the specific recognition of anti-CEA and CEA. This PEC immunosensor shows a wide linear response to CEA ranging from 0.0005 to 50 ng ml(-1) with a low detection limit of 0.14 pg mL(-1). The proposed immunosensor has good stability, reproducibility and high specificity. The satisfied results are also obtained when this immunosensor is used to detect CEA in actual human serum samples analysis, thus opening up a new promising PEC analysis platform based on conducting polymers.