Photoanode-supported cathodic immunosensor for sensitive and specific detection of human chorionic gonadotropin.

Target biomarker detection with high accuracy in biological sample is necessary for the constructed immunoassays. Herein, a novel and enhanced cathodic immunosensor supported by photoanode was designed for sensitive and specific detection of human chorionic gonadotropin (HCG). Specifically, the electrode of TiO2 nanotube with N doping (TiO2:N) was fabricated and assembled with AgInS2 quantum dots (QDs) to acquire the TiO2:N/AgInS2 photoanode. For the sensing cathode, Pt nanoparticles (NPs) were decorated on carbon nanotubes (CNTs) to prepare the CNT/Pt cathodic matrix and was used to modify capture HCG antibody (Ab). In this photoelectrochemical (PEC) sensing system, the TiO2:N/AgInS2 photoanode served as the signal-converting element to produce prominent current signal, while the immune recognition events occurred on the sensing cathode to evidently change the initial current signal from steric hindrance effect. Profiting by excellent photoelectric property and good anti-interference ability of this featured PEC system, the developed cathodic immunosensor demonstrated high sensitivity and specificity for the detection of target HCG antigen (Ag). This photoanode-supported cathodic sensing strategy provided a potential path forward to exploit other enhanced PEC immunosensors in the application of biological samples.