Synergistic enhancement via surface plasmon resonance and Schottky junctions for high-performance photoelectrochemical MiRNA biosensing.

Photoelectrochemical (PEC) sensors exhibit significant promise for early disease diagnosis and trace-level biomarkers detection, owing to their exceptional sensitivity, strong anti-interference capacity. Nevertheless, the relatively low photoelectric conversion efficiency remains a limiting factor for their detection performance. In this paper, a high-performance PEC sensing strategy was proposed based on the engineered dual active centers of surface plasmon resonance and oxygen vacancy in the homologous Bi-Bi2O3 Schottky heterojunction structure. With this configuration, the photocurrent response was significantly enhanced by interface band structure regulation. To achieve higher sensitivity in photocathode analysis, a duplex-specific nuclease-assisted cycle strategy was employed to stabilize the photocurrent signal, and AgInS2 quantum dots were used as electron traps to collect photogenerated electrons in Bi-Bi2O3, which resulted in the signal being further amplified. By precisely capturing significant variations in the photocurrent signals, highly sensitive detection of microRNA166a was achieved, with a low detection limit (5.6 pM) and a broad linear detection range (10 pM to1μM). This work established the basis for efficient signal modulation strategies in high-performance PEC sensors.