Rapid, sensitive, and convenient magnetic surface-enhanced raman spectroscopy substrate based on Fe₃O₄/C/SiO₂-SH for aflatoxin B1 detection

A rapid, sensitive, and convenient surface-enhanced Raman spectroscopy (SERS) substrate was developed using Fe₃O₄/C as the magnetic core and SiO₂-SH as the shell for the detection of aflatoxin B1 (AFB1). Ultra-small Fe₃O₄/C nanoparticles (NPs) with an average size of 6.30 ± 0.68 nm and excellent magnetic responsiveness were synthesized via a one-pot hydrothermal method, followed by the deposition of a uniform SiO₂ shell, followed by thiol-group functionalization to yield Fe₃O₄/C/SiO₂-SH. The magnetic core enables instantaneous separation of the substrate from solution after AFB1 adsorption, eliminating the need for centrifugation or filtration. When employed as a SERS substrate, significant enhancement of the characteristic Raman peak at 1482 cm⁻ 1 was observed across AFB1 concentrations of 0.1–10 μg/mL. Notably, the peak intensity at 10 μg/mL exceeded that of solid AFB1 powder. Comprehensive characterization (TEM, XRD, FTIR, XPS, and vibrating sample magnetometry) confirmed the core–shell structure, high crystallinity, and strong magnetic properties. The prepared Fe₃O₄/C/SiO₂-SH nanocomposite offers a low-cost, easily recyclable, and noble-metal-free platform, demonstrating strong potential for trace AFB1 monitoring in herbal medicines and food products.