Bioderived establishment of three-dimensional type-I Ag2S/ZnIn2S4 heterojunction for high-efficacy organic photoelectrochemical transistor biomolecular detection

Advanced optoelectronic devices have attracted extensive interdisciplinary interest but lags far behind in biomolecular detection. The nascent organic photoelectrochemical transistor (OPECT) is expected to become a versatile platform to this end. Herein, using biological derivation of type-I Ag2S/ZnIn2S4 heterojunction, a light-fueled high-efficacy OPECT system with zero-gate-biased operation is successfully developed for biomolecular detection. Exemplified by a sandwich immunocomplexing towards mouse IgG (MIgG) with Ag nanoparticles (Ag NPs) as the label, steering the acidolysis-release of Ag+ toward ZnIn2S4 could induce the in-situ formation of type-I Ag2S/ZnIn2S4 heterojunction, increasing the recombination of light-activated excitons and thus inhibiting the photo-responsibility of ZnIn2S4, as sensitively monitored by the amplified OPECT response. The proposed device could achieve good analytical performance in terms of high specificity and sensitivity, with a detection limit as low as 33.7 fg mL-1. This OPECT device based on bio-induced formation of type-I heterojunction can provide a novel route to biomolecular detection, and offered a new perspective for the optoelectronic sensors to be used in futuristic physiological and pathological detection.