HOF-101/AgInS₂ photogate-engineered organic photoelectrochemical transistor for amplified miRNA-21 biosensing

Nucleic acid detection requires sensitive and controllable signal transduction strategies for reliable bioanalysis. Organic photoelectrochemical transistor (OPECT) provides a promising platform for transistor-level signal amplification, while its analytical performance is strongly dependent on photogate design and interfacial signal transduction.

Herein, we report a photogate-engineered OPECT for transistor-amplified biosensing of miRNA-21, enabled by a HOF-101/AgInS₂ heterojunction. The integration of AgInS₂ quantum dots with a photosensitive hydrogen-bonded organic framework (HOF-101) forms an efficient photogate, promoting photoinduced charge separation and enabling light-driven modulation of the interfacial gate potential. Upon target recognition, catalytic hairpin assembly (CHA) triggers rolling circle amplification (RCA), producing G-rich DNA strands that, in the presence of hemin, generate peroxidase-mimetic catalytic centers. These catalytic units then mediate enzymatic precipitation at the photogate interface, leading to the accumulation of insulating deposits. The resulting interfacial deposition modulates the photogating response and effective gate voltage, thereby transducing molecular recognition events into amplified transistor current responses. This molecular-to-transistor signal transduction pathway enables highly sensitive and selective measurement of miRNA-21. The present design provides a strategy for integrating photoresponsive interface engineering with transistor-level amplification for advanced bioanalysis.