A Triple-Functional CuO@PANI@l-His Architecture for Nanozyme-Enhanced Photoelectrochemical Chiral Sensing of DOPA Enantiomers.

Developing highly sensitive strategies for enantiomeric analysis remains a major challenge in chiral sensing, particularly for discriminating biomedically important enantiomers such as l-/d-3,4-dihydroxyphenylalanine (l-/d-DOPA). Here, we developed a triple-functional CuO@PANI@l-His architecture that integrates enhanced photoelectrochemical (PEC) properties, nanozyme activity, and chiral recognition capability into the proposed sensing platform for highly sensitive and enantioselective detection of l-/d-DOPA. Hollow CuO@PANI polyhedra were synthesized to form a Z-scheme band alignment, which promoted charge separation and improved the PEC response. Meanwhile, the peroxidase-like activity was markedly boosted through the coupling of polyaniline (PANI) with CuO, enabling efficient nanozyme-catalyzed oxidation of 4-chloro-1-naphthol (4-CN) into the insoluble benzo-4-chloro-hexadienone (4-CD) product, thereby producing a pronounced photocurrent suppression. Covalently immobilized l-histidine (l-His) acted as a chiral selector that generated stereospecific binding sites, thereby inducing differential inhibition of the nanozyme catalytic activity toward l-DOPA and d-DOPA. Driven by the Z-scheme structure, nanozyme-mediated signal amplification, and enantioselective interactions, the resulting PEC sensing platform exhibited broad linear ranges (0.1-1000 μM for l-DOPA and 1-1000 μM for d-DOPA), low detection limits (0.031 μM for l-DOPA and 0.476 μM for d-DOPA), and high enantioselectivity with a separation factor (ΔId-DOPA/ΔIl-DOPA) of 4.6. By integrating nanozyme catalysis with enantioselective recognition into a PEC sensing platform, this work opens new avenues for the development of highly sensitive and enantioselective sensors for chiral molecules.