Heterojunction-Amplified Photoionic Transduction in MoS2 Lamellar Nanochannels for Microcystin-LR Detection

Abstract

Trace molecular recognition at solid-state nanochannels often produces surface-charge perturbations that are too small to be resolved by conventional voltage-driven ionic-current measurements. Here, we developed a heterojunction-amplified photoionic transduction strategy for microcystin-LR (MC-LR) detection by constructing a MoS2/C60−NH2 heterojunction on the outer surface of MoS2 lamellar nanochannels. The heterojunction facilitated photogenerated carrier separation and interfacial charge redistribution, creating a photoresponsive interface with enhanced sensitivity to weak recognition-induced surface charge perturbations. Localized 430 nm illumination drove lateral ionic transport through the nanochannels at zero external bias, while aptamer recognition of MC-LR modulated the photoinduced interfacial response through changes in the outer-surface charge state, resulting in pronounced ionic current changes. The heterojunction-modified nanochannels achieved a limit of detection (LOD) of 7.1 × 10−9 μg/L, with a linear range of 10−8-10−3 μg/L, representing an improvement of 5 orders of magnitude relative to conventional voltage-driven operation. Recoveries of 93.96−102.0% were obtained in spiked tap, lake, and mineral water samples. Non-Faradaic electrochemical impedance spectroscopy (EIS) indicated that the enhanced response was predominantly reflected in the fitted interfacial impedance contribution, whereas the diffusion-related ionic transport contribution changed only slightly. This work establishes a heterojunction-engineered route to tune the interfacial transduction gain, opening opportunities for high-sensitivity sensing in photoresponsive 2D nanochannels.