Defect-engineered MOF-based magnetic SERS substrate with “berries-on-hedgehog” morphology for sensitive detection of organophosphorus pesticide residues in rice samples

To address the issue of insufficient affinity of Surface-Enhanced Raman Scattering (SERS) substrates for organophosphorus pesticides, this study proposes an innovative strategy: utilizing electrostatic self-assembly to uniformly coat small-sized UiO-66 nanoparticles, prepared via metal-organic framework defect engineering, onto the surfaces of prickly noble metal nanoparticles, thereby constructing a shell rich in defect sites. This strategy successfully synthesized the "berries-on-hedgehog" morphology SERS substrate DU-W, which exhibited high sensitivity towards edifenphos in the SERS response. The SERS enhancement factor of the DU-W substrate was 1.54 × 10⁷, with a 50 d shelf life at 4 °C, and demonstrated good repeatability and uniformity. Furthermore, the DU-W substrate achieved precise quantitative detection of edifenphos residues in rice samples, with a detection limit of 0.03 mg/kg, demonstrating its excellent application potential. This research presents novel insights into the design and synthesis of customizable SERS substrates, offering technical and theoretical guidance for sustained advancement and broad application of SERS technology.