Flexible SERS sensing platform with MOF-enabled trapping for sensitive swab sampling monitoring of ferbam fungicide residues on fruit surfaces.

The extensive use of the fungicide ferbam in food matrices necessitates effective monitoring due to its toxicity; however, constructing flexible on-site sensing platforms for the sensitive and rapid trace-level analysis of ferbam remains highly challenging. Herein, we report a flexible filter paper-supported silver nanowire@zeolitic imidazolate framework-8 (FP/AgNWs@ZIF-8) sensing platform for the surface-enhanced Raman spectroscopy (SERS) detection of trace ferbam pesticide residues on fruit surfaces. The effect of ZIF-8 growth time on the Raman signal of the sensing platform was investigated, and 40 min was identified as the optimal growth time for enhancing the Raman response toward aromatic molecules, such as methylene blue (MB), 4-mercaptobenzoic acid(4-MBA)， and malachite green (MG). Under this condition, the FP/AgNWs@ZIF-8 sensing platform showed strong linearity for MB concentrations ranging from 10-6 M to 10-10 M, with a low limit of detection (LOD) of 1.17 × 10-11 M, good uniformity, and strong batch-to-batch stability. When applied to ferbam detection, the sensor shows good linearity over a concentration range from 10-3 to 10-7 M, with an LOD as low as 10-7 M, good reproducibility, and strong batch-to-batch stability. In addition, the sensor is capable of determining trace ferbam residues on apple surfaces, as demonstrated by wiping-sampling experiments, showing reliable linear detection of ferbam over a wide concentration range. Overall, the proposed synergistic interplay between the electromagnetic and chemical mechanisms intrinsic to the metal-organic framework-based SERS platform provides a viable strategy for trace pesticide analysis in fruits and vegetables.