Biofunctional photoelectrochemical immunosensor based on Ag– AgI/BiOI– Bi2O3 for the rapid detection of squamous cell carcinoma antigen

Squamous Cell Carcinoma Antigen (SCCA), as a key tumor marker, with significant clinical value in the early diagnosis, efficacy evaluation, and recurrence monitoring of squamous epithelial carcinomas such as lung cancer, cervical cancer, and esophageal cancer. However, the existing detection methods often suffer from limitations including complex operation, high detection limit and strong instrument dependence. Photoelectrochemical (PEC) immunoassay has emerged as a promising approach for tumor marker detection due to its advantages of low background interference, high sensitivity and simple operation. In this study, we developed a novel PEC immunosensor for the rapid detection of SCCA. The sensor was constructed based on an Ag-AgI/BiOI-Bi₂O₃ composite material, synthesized via a one-step hydrothermal method, which exhibited a strong photoelectric response under visible light irradiation. This composite material enhanced the electron-hole separation and conductivity, significantly improving the PEC performance and enabling highly sensitive and specific detection of SCCA. Experimental results indicated that the sensor displayed an excellent logarithmic linear relationship within the SCCA concentration range of 0.0001 ng/mL to 10 ng/mL, having a detection threshold as low as 0.04 pg/mL. Furthermore, the sensor exhibited high accuracy and stability accuracy and stability for the detection of real serum samples. Compared with previously reported methods, this PEC immunosensor offers the advantages of simpler operation, a lower detection limit, and higher sensitivity, providing a novel and effective strategy for the clinical detection of SCCA.