Optimal bimetallic Au@Ag nanocuboids-based SERS sensor for label-free ultrasensitive detection of florfenicol residue in eggs.

A label-free surface-enhanced Raman scattering (SERS) sensor using optimal bimetallic Au@Ag nanocuboids (Au@Ag NCs) was developed for ultrasensitive detection of florfenicol residue in eggs. The Raman characteristic peaks of florfenicol detection were identified at 1145 cm and 1595 cm which were consistent with the theoretical Raman spectrum of florfenicol calculated by density functional theory. The Au@Ag NCs were optimized by changing the aspect ratio of Au nanorods and the thickness of Ag nanocuboids, achieving an enhancement factor of 1.69 × 10 for SERS signals. Under optimal conditions, the label-free SERS sensor demonstrated a broad linear range of 0.01 mg/kg to 100 mg/kg for florfenicol in real sample. The limit of detection of florfenicol in eggs was as low as 0.0410 μg/kg, and the recovery was 94.83% ~ 108.24%. Therefore, this label-free SERS sensor offers a rapid and sensitive approach for the trace detection of florfenicol residues in food safety monitoring.