Near-Infrared Light Driven Reversible Photoelectrochemical Bioassay by S-Scheme All-Polymer Blends for Acetylcholinesterase Activity Monitoring

Photoelectrochemical (PEC) biosensing, recognized for its heightened sensitivity, faces limitations in its application for in vivo diagnosis due to the inefficiency of UV–visible light-driven photoactive materials in nontransparent biological samples. In this study, we investigate the potential of an S-scheme all-polymer heterojunction comprising a prototype nonfullerene polymeric acceptor (PYIT) and carbon nitride to develop a near-infrared (NIR) light-driven PEC biosensor for monitoring acetylcholinesterase activity in nontransparent human whole blood. The distinct molecular structure of PYIT enables efficient light absorption in the NIR region, enhancing sensitivity in nontransparent biological samples. The biosensor functions via a proton-dependent conversion mechanism between PYIT-OH and PYIT, leveraging the selective and reversible chemical reactivity of the moieties in backbone, eliminating the need for traditional and intricate integration of a biorecognition unit. Our findings demonstrate a direct correlation between variations in photoelectric performance and acetylcholinesterase concentration, showcasing exceptional sensitivity, selectivity, and reversibility.