Constructing hot-spots enriched Ag/MoS hybrid SERS platform for rapid detection of pesticide residue in juice.

Excessive pesticide residues have posed a severe risk to human health and ecological environment, making stringent testing of them a crucial step in food safety supervision. Herein, a flexible paper-based SERS platform composed of AgNPs and MoS nanoflowers was developed for the rapid and ultra-sensitive detection of thiram in juice. Among it, the hydrophobic MoS-modified paper was first fabricated, followed by co-depositing small-sized AgNPs and thiram molecules onto its surface for SERS analysis. Owing to the unique petal-like structure and high hydrophobicity of MoS-coated paper, the AgNPs loaded on it were significantly aggregated, thereby generating numerous "hot spots" in the nanogaps between adjacent silver nanoparticles. Simultaneously, thiram molecules were enriched and concentrated within these gaps, resulting in exceptional Raman signal amplification. Compared to single-material substrates, an integrated advantage was acquired with hybridizing of AgNPs and MoS. The performance of this platform was verified by detecting thiram in pear juice using a portable Raman spectrometer, in which the limit of detection (LOD) can be as low as 1.01 ng/mL and its recovery percentages had a good consistency with ones of HPLC-MS/MS. Overall, this Ag/MoS hybrid SERS platform exhibits outstanding stability, sensitivity and feasibility in the label-free detection of pesticides in food. It also provided a universal tool for the on-site monitoring of diverse biochemical molecules across various fields.