Label-free photoelectrochemical immunoassay for CEA detection based on CdS sensitized WO3@BiOI heterostructure nanocomposite

In this work, a label-free photoelectrochemical (PEC) immunosensor for the detection of carcino embryonic antigen (CEA) was developed based on CdS nanowires (NWs) sensitized WO3@BiOI heterostructure. The construction procedure of ITO/WO3@BiOI@CdS electrode was done by dipping the WO3@BiOI modified indium-tin oxide (ITO) electrode interchangeably into [Cd(NH3)4]2+ and S2- solution for several times. Then the ITO/WO3@BiOI@CdS electrode was used as a matrix for the subsequent immobilization of CEA antibody (Ab). The obtained label-free PEC immunosensor showed an excellent PEC performance toward CEA detection. Under optimal conditions, the PEC immunosensor have a sensitive response to CEA in a liner range of 0.01 ng/mL to 50 ng/mL with a detection limit of 3.2 pg/mL. The proposed PEC immunosensor exhibited good stability, high sensitivity as well as reproducibility and storage stability. Moreover, the obtained PEC immunosensor also showed a satisfied result in human serum sample analysis.