Laser-driven molecular hybridization of Sm(OH)3:Se nanocomposites with tailored electronic states for antibiotics sensing

Ensuring food safety requires advanced hybrid materials capable of detecting trace antibiotics within complex plant matrices. We introduce a laser-induced molecular engineering (LIME) strategy to fabricate a selenium-integrated samarium hydroxide and graphene (Gr/Sm(OH)3:Se) nanocomposite engineered for direct electrochemical detection of sulfamethoxazole (SMX) in cultivated lettuce tissue. Unlike conventional laser processing techniques that primarily induce surface texturing, LIME enables molecular-level integration of functional elements, producing defect-rich interfaces with enhanced electron mobility and abundant active sites. Comprehensive characterization confirms that localized photothermal and photochemical effects promote the uniform incorporation of Se into the Sm(OH)3 lattice and convert surface M–OH groups into M–O linkages, thereby generating holes in the O 2p valence band and improving both electron transfer kinetics and the selectivity toward SMX adsorption. The resulting sensor exhibits high sensitivity (1.83 µA (µg/g)−1 cm− 2), excellent selectivity, and long-term stability (> 30 days), enabling reliable trace-level detection without artificial sample spiking. Analysis of real samples further reveals higher SMX accumulation in lettuce irrigated with SMX-contaminated water. This study establishes LIME as a versatile and controllable approach for molecularly engineering electrode materials, thereby advancing the real-world monitoring of antibiotic residues in plants.