MOF-Derived In2S3@ZnIn2S4 Hollow Nanotube Heterojunction for Regenerable Photoelectrochemical Detection of Penicillin G

Abstract

Penicillin G (PG) residues in animal-derived foods accelerate antimicrobial resistance and threaten human health. Conventional metal sulfide photoelectrodes suffer from rapid carrier recombination limiting photoelectrochemical (PEC) sensor performance for antibiotic monitoring. To address this, we report a metal–organic framework (MOF)-derived hollow In2S3@ZnIn2S4 coaxial heterojunction with type-II band alignment, fabricated via a one-pot oil-bath method. The intimate coaxial heterojunction between the ZnIn2S4 shell and the In2S3 core facilitates spatial separation of photogenerated electron–hole pairs, with electrons migrating toward the inner core and holes toward the outer shell. This spatial charge separation suppresses recombination and decouples optical absorption from carrier collection, greatly enhancing PEC performance. The platform integrates a regenerable DNA conformational transition, wherein Ag+-induced folding of C-rich DNA is reversed by l-cysteine (l-Cys) chelation of Ag+, restoring the single-stranded state for repeatable PG quantification. The sensor exhibits a wide linear range (1.0 pg·mL–1 to 1.0 μg·mL–1) and a low limit of detection (0.88 pg·mL–1). Standard addition assays in milk and human serum samples show recoveries of 104.68–113.31% and 96.44–111.29%, respectively, confirming reliable practical applicability. This study provides a simple strategy for synthesis of high-efficiency chalcogenide photoactive materials and demonstrates regenerable heterojunction-based PEC biosensors for antibiotic residue monitoring.