Colorimetric and SERS dual-mode sensing of capsaicin based on Au@PtNPs with enhanced peroxidase-like activity for gutter oil discrimination

The development of a capsaicin detection system that integrates facile preliminary evaluation with high sensitivity and accuracy across a wide detection range is crucial for the discrimination of gutter oil and the protection of human health. In this study, we constructed a novel colorimetric/SERS dual-mode detection system utilizing peroxidase-like Au@Pt nanoparticles (NPs) that exhibit SERS-activity. The Au@Pt NPs feature a spherical gold nanoparticle core with synapse-like platinum nanoparticles distributed intermittently on their surface, this structure enhances the catalytic activity of the PtNPs and the SERS activity of the AuNPs, making them ideal for designing colorimetric/SERS dual-mode probes. Based on the colorimetric assay, we achieved a capsaicin detection range from 1 to 10,000 μM, with a limit of detection (LOD) of 3.48 μM, as determined by absorption spectroscopy analysis. Additionally, a linear calibration curve for capsaicin ranging from 10 −9 to 10 −5  M was established using the SERS method, yielding an LOD of 7.38 nM. By integrating the advantages of facile detection through colorimetric analysis with the high-sensitivity trace assay provided by SERS, this proposed dual-mode detection system demonstrates excellent sensitivity, reliability, selectivity, and wide detection range compared to previous probes and methods. Consequently, this method can serve as an efficient tool for monitoring oil quality.