Surface Modified Ag Nanowires as Effective, Flexible-Patterned SERS Substrates for the Detection of Fishery Drugs

This study introduces a flexible and cost-effective surface-enhanced Raman scattering (SERS) substrate incorporating surface-modified silver nanowires (AgNWs) and sandpaper-assisted soft lithography. AgNWs were chemically roughened to enhance surface roughness, thereby increasing the density of SERS-active hotspots. The modified AgNWs were then embedded into a polydimethylsiloxane (PDMS) matrix to form a hybrid SERS substrate (SMAW) with enhanced mechanical flexibility, stability, and signal reproducibility. The sandpaper-templated PDMS surface further contributed to SERS performance by introducing microstructures that amplified localized electromagnetic fields and improved molecular adsorption. The developed SMAW hybrid substrate exhibited outstanding SERS sensitivity, achieving analytical enhancement factors of 10⁷ for crystal violet (CV) and 10⁶ for malachite green (MG), with nanomolar-level detection limits. Raman mapping and point-to-point measurements demonstrated uniform signal distribution across the substrate, while long-term stability tests over 60 days revealed minimal signal variation (RSD = 3.68%), ensuring consistent analytical performance. Furthermore, PDMS encapsulation prevented AgNW oxidation, significantly improving substrate durability. Designed for practical applications, this flexible SERS substrate enables direct and nondestructive detection of fishery drug residues from aquatic product surfaces via surface swab sampling. By integrating nanomaterial surface engineering, microstructured polymer substrates, and analytical sensing, this study provides a highly sensitive and reproducible method for real-world food safety monitoring.