Transparent and stretchable SERS substrates via interfacial transfer self-assembly for in-situ trace thiram fungicide residues detection in fruits

In this work, a series of flexible-transparent polydimethylsiloxane@Ag nanoparticle (PDMS@AgNPs) SERS substrates were fabricated for highly sensitive in-situ detection of trace thiram fungicide residues on various fruit surfaces. By regulating interfacial transfer self-assembly, abundant SERS “hot spots” were generated on the PDMS@AgNPs surface, as confirmed by finite-difference time-domain simulations. Using 4-mercaptobenzoic acid (4-MBA) as a probe molecule, the substrates achieved a low detection limit of 10⁻⁸ M and a high enhancement factor of 2.14 × 10⁶. Critically, the PDMS@AgNPs substrates exhibited excellent transparency and stretchability, enabling in-situ detection on irregular surfaces. The PDMS@AgNPs substrates were prominent platform to identify thiram residues on apples, pears, and grapes with the detection limits of 0.048 μg/cm², 0.20 μg/cm², and 0.24 μg/cm², respectively. This strategy provided a convenient approach for in-situ pesticide residues detection on the surfaces of fruits and vegetables in the food safety field.