Sensitive ratiometric detection of Fumonisin B₁ using a reusable Ag-pSi SERS platform

Food and agricultural commodities endure consistent contamination by mycotoxins, low molecular weight fungal metabolites, which pose severe health implications to humans together with staggering economic losses. Herein, a ratiometric aptasensor was constructed using silver-coated porous silicon (Ag-pSi) used as an efficient surface-enhanced Raman scattering (SERS) substrate. The bioassay included direct detection of fumonisin B₁ (FB₁), an abundant and widespread contaminant, by a specific aptamer sequence immobilized on the porous transducer. The inherent surface void and pore morphology were physically optimized to achieve a sufficient SERS effect (enhancement factor > 5 × 10⁷). Under optimal conditions, the aptasensor exhibits high sensitivity, wide dynamic range, signal stability, selectivity and regeneration for consecutive FB₁ detection (0.05 ppb, 0.1-1000 ppb, RSD of 5.2 %, no interference with competing mycotoxins and eight regeneration cycles, respectively). The efficacy of the designed aptasensor was elucidated in various spiked matrices (maize, onion, wheat and milk) with averaged recovery values of 93.3-113.6 % and satisfactory consistency with HPLC data for representative foodstuffs. Overall, the resulting validation emphasizes the transducer's reliability and suitability for practical use, including on-site analysis.