Self-powered dual-photoelectrode photoelectrochemical aptasensor amplified by hemin/G-quadruplex-based DNAzyme

A self-powered dual-electrode aptasensor was developed for the detection of tumor marker carcinoembryonic antigen (CEA). The composite BiVO₄/ZnIn₂S₄, which is capable of forming a Z-scheme heterojunction, was chosen as the photoanode, and the AuNP/CuBi₂O₄ complex was chosen as the photocathode in photoelectrochemical (PEC) detection. The experiments showed that the constructed self-powered dual-electrode system had a good photoelectric response to white light, and the photocurrent signal of the photocathode was significantly enhanced under the influence of the photoanode. The introduction of G-quadruplex/hemin DNAzyme through aptamer recognition resulted in the generation of insoluble species through catalytic reaction, which led to a significant decrease in the photocurrent, and achieved a highly sensitive detection of the target CEA with a detection limit of 0.021 pg/mL. At the same time, the developed photocathode detection exhibited good selectivity and could effectively avoid interference, making it suitable for real sample analysis. It is expected that this study can facilitate the application of PEC sensors in point-of-care (POC) diagnosis for life analysis.