Sensitive and reliable detection of deoxynivalenol mycotoxin in pig feed by surface enhanced Raman spectroscopy on silver nanocubes@polydopamine substrate.

Deoxynivalenol (DON) is one of the trichothecene mycotoxin, a frequent contaminant of pig feed. Surface-enhanced Raman spectroscopy (SERS) is a fast and ultrasensitive analytical tool for point-of-need applications to identify molecular fingerprint structures at low concentrations. However, the use of SERS for analyte detection with flexible and robust structures is still challenging. Herein, we have developed core-shell silver nanocubes coated with polydopamine (Ag NCs@PDA) SERS substrate for the quantitative detection of deoxynivalenol in pig feed. The Ag NCs@PDA substrate with ultrathin (1.6 nm) PDA shell thickness enhances the absorption of DON via hydrogen bonding and π-π stacking interactions, as well as improves the stability of the substrate. The results of the SERS showed a high analytical enhancement factor (AEF) of 1.82 × 10 and a detection limit (LOD) as low as femtomolar range (0.82 fM). The LOD of the Ag NCs@PDA substrate for DON detection is 1.8 times lower than the bare Ag NCs. Furthermore, the Ag NCs@PDA substrate is stable which retains 88.24% of the original Raman intensity after storage for three months. The obtained results demonstrate that the Ag NCs@PDA substrates can realize label-free detection of deoxynivalenol mycotoxin with high sensitivity, reproducibility, and stability. Our work proposes a low-cost method for the designing of the SERS sensing device, and has great potential to be applied in food safety, biomedical sciences, and environmental monitoring.