Multi-Level Asymmetric Mesoporous Nanochannels for Photothermal-Regulated Dopamine Sensing

Bioinspired nanochannel systems provide attractive platforms for coupling molecular recognition with ion transport regulation; however, integrating selective binding with efficient signal amplification remains challenging. In this study, we report a multi-level light-responsive asymmetric mesoporous nanochannel constructed via sequential interfacial assembly. The device consists of a dopamine-recognition mesoporous TiO₂ (NMTI) layer integrated with a photothermally active mesoporous carbon/γ-Fe₂O₃ heterostructure on an anodic aluminum oxide scaffold (NMTI/AAO/MC-γ-Fe₂O₃). Dopamine is selectively captured through strong catechol-Ti coordination accompanied by proton transfer, inducing surface-charge modulation, and ion enrichment within the nanochannels. This recognition process enhances ionic conductance, while the MC-γ-Fe₂O₃ layer converts optical energy into localized heating, enabling photothermal regulation of ion transport. The synergistic coupling of molecular recognition, surface-charge regulation, and photothermal ion transport enables light-tunable dopamine sensing with an expanded dynamic range and an ultralow detection limit of 10 pM under illumination. The sensing mechanism, spanning molecular adsorption, nanoscale ion redistribution, and macroscopic current amplification, is elucidated through multiscale theoretical analyses, including density functional theory (DFT), molecular dynamics (MD), and finite element simulations. This work establishes a general strategy for integrating molecularly specific recognition and photothermal signal amplification in hierarchical nanochannel systems, providing new design principles for high-performance bioinspired sensing platforms.