Interface self-shelling effect-mediated photoinduced carrier transport and multiplexed signal amplification mechanism in self-powered photoelectrochemical biosensing

In the realm of biomedical diagnostics, the development of sensitive and specific detection methods for cancer biomarkers is of paramount importance. Herein, we report on the design and implementation of a self-powered photoelectrochemical (PEC) sensor that harnesses amplified photocathode signals for the deterioration of carbohydrate antigen 125 (CA125) associated with ovarian cancer. This self-powered sensing platform integrates Cu₂O/Cu₃SnS₄ heterojunction and ZnIn₂S₄ sensitized TiO₂ with flower-like structure as photocathode and photoanode. Moreover, the PEC biosensor introduces the interface shedding effect to overcome the limitations of weak or unstable photocathode PEC signals. When MnO₂ nanoparticles are used as the quenching source, the cathode photocurrent experiences a reduction to a certain extent owing to the phenomenon of competitive light absorption. To enhance the application for efficient CA125 detection, the interface self-shelling effect is introduced. The effect is implemented through the hydrolysis reaction of Acetylcholinesterase (AChE), producing thiocholine (TCh) as the interface detachment initiator. Which resulting in the detachment of layer modifiers, including MnO₂, from the electrode surface and achieving the effect of significant enhancement of the photoelectric signal. Therefore, multiple signal amplification effects synergistically enhanced the photoelectric response. The self-powered PEC biosensing with a wide linear range of 0.001 U/mL-200 U/mL and a low detection limit of 0.32 mU/mL, which shows excellent performance in terms of sensitivity, specificity, and stability, making it a promising candidate for point-of-care diagnostics.