Flexible Nylon-Ag@4MBA substrate-based SERS for rapid and ultrasensitive detection of carbendazim on fruit surfaces

Nylon shrinkage effect generates dense SERS hotspots. • Ultrahigh sensitivity, achieving a detection limit of 10 −9  M for the probe molecule R6G. • Excellent uniformity and reproducibility, with a relative standard deviation (RSD) of 5.14% across 50 random spots. • Superior long-term stability, retaining 89.23% of the initial SERS signal after 30 days of storage. • Paste-and-peel method for in-situ CBZ detection on fruit. To address the widespread issue of carbendazim (CBZ), a common pesticide residue, on the surfaces of fruits and vegetables, our research team prepared silver nanoparticles using the sodium citrate reduction method and successfully loaded them onto a nylon membrane substrate via vacuum-assisted filtration. Subsequently, the substrate was modified with 4-mercaptobenzoic acid (4-MBA) as an internal standard signaling molecule, yielding a Nylon-Ag@4MBA flexible surface-enhanced Raman spectroscopy (SERS) substrate. The as-prepared Nylon-Ag@4MBA substrate exhibited excellent uniformity (RSD = 5.14%), a detection limit as low as 10 −9  M for the R6G probe molecule, and a signal retention rate of 89.23% after 30 days of storage. In the detection of actual samples such as apples, the recovery rates of CBZ ranged from 95.05% to 96.90% with relative standard deviations (RSDs) below 4.07%, demonstrating reliable quantitative capability. No interference was observed from common substances on the fruit peel. This study confirms the potential application of the Nylon-Ag@4MBA substrate for the on-site rapid detection of pesticide residues. Download: Download high-res image (81KB) Download: Download full-size image