A flexible and reusable self-assembled SERS sensor: One-step sampling and on-site detection of bifenthrin in foods

A reusable and flexible surface-enhanced Raman spectroscopy (SERS) sensor was constructed through an interfacial assembling strategy for rapid and non-destructive detection of bifenthrin in foods. The sensor was fabricated through rational integration of two components: (1) a plasmonic ternary Au@Cu₂O@Ag nanoarrays synthesized via liquid-liquid interface self-assembly (LLISA) on Teflon tape, and (2) an epoxy resin (EP) encapsulation layer. The Au@Cu₂O@Ag nanoarrays demonstrated exceptional SERS performance due to synergistic plasmonic enhancement effects from the Au core, charge transfer mediation via the Cu₂O interlayer, and secondary electromagnetic field amplification by the Ag shell. The Teflon tape ensured uniformity of the SERS “hot spots”, while EP encapsulation provided mechanical durability and oxidation resistance. Unlike traditional methods (e.g., HPLC, GC) requiring extensive pretreatment and hours-long analysis, the flexible SERS sensor allowed one-step and pretreatment-free sampling and on-site detection of bifenthrin on irregular food surfaces, delivering laboratory-grade quantification of bifenthrin within 3 minutes. Under optimal testing conditions, the sensor exhibited a low limit of detection (1.81 × 10^-9 μmol/L) and a wide linear response range of 10^-8-10³ μmol/L. Additionally, the flexible SERS sensor demonstrated high accuracy in bifenthrin-spiked food samples with recoveries of 94.18%-104.53%. Notably, the developed sensor exhibited practical applicability in bifenthrin quantification across four real food samples, demonstrating excellent agreement with standard gas chromatography (GC), thereby validating the reliability of the proposed method.