A SERS swab based on plasmonic MXene hydrogel for on-site identification of drug residues in agriculture.

Drug residues in agriculture pose a critical threat to food safety and public health. Constrained by the complex requirements for sample preparation, traditional pesticide residue monitoring methods are difficult to carry out on-site. To address this challenge, this study developed a surface-enhanced Raman spectroscopy (SERS) swab based on plasmonic MXene hydrogel for highly sensitive identification of drug residues. This swab was obtained by in-situ curing of alginate hydrogel on a commercial sampling swab. Alginate hydrogels, serving as efficient porous carriers for MXene adsorbents and SERS-active nanobones, simultaneously ensure the stability of the nanomaterials and the convenience of sampling. Benefiting from the ultra-high sensitivity originated from MXene and nanobones, this swab can extract and analyze trace drug residues from the surface of agricultural products via direct wiping in 30 s. In tests of real samples,this swab demonstrated features including rapid response, high sensitivity, and low cost, indicating the promising potential for in-field application.