Modulation of Electron Transport via Target Recognition in Asymmetric Nanochannel Arrays for Enantiomer Detection

Chirality pervades biological architecture, and therapeutics that interface with living systems likewise manifest as stereoisomeric pairs whose divergent metabolic fates engender distinct pharmacological outcomes. Accordingly, the creation of facile, cost-effective platforms for enantiomer discrimination is pivotal both to chiral-drug development and to elucidating biochiral-material interactions. Here we engineer an asymmetric nanoelectrode by partitioning a single TiO₂ nanochannel membrane (TiO₂M) into spatially discrete "recognition" and "reporting" domains. Gold nanoparticle decoration enables covalent anchoring of l-cysteine (Cys) via Au-S bonds at one face of TiO₂M, establishing a stereospecific binding interface; copper-based metal-organic frameworks (Cu-MOFs) are grown on the trans face to serve as redox-active reporters. Using l-/d-dihydroxyphenylalanine (DOPA) as the model enantiomers, selective binding of l- or d-DOPA at the l-Cys interface initiates electrochemical oxidation that injects electrons into the Au/TiO₂ conduit; these electrons traverse the nanochannel and reduce Cu(II) to Cu(I) within the distal MOF layer, thus modulating the surface charge and producing a discernible transmembrane current shift. Differential hydrogen-bonding competencies of l- versus d-DOPA with l-Cys translate into quantitatively distinct charge perturbations, thereby affording high-fidelity enantiomer recognition. This longitudinally segmented TiO₂ nanochannel architecture thus converts stereospecific molecular interactions into amplified electronic signatures, offering a versatile blueprint for next-generation electrochemical sensors targeting chiral analytes.