SERS sensor based on Au@AgNPs modified with UiO-66 and Leu for highly sensitive detection of chlorthiamid in food

A novel UiO-66/Leu/Au@AgNPs SERS substrate was fabricated for chlorthiamid detection. • A low LOD of 1.95 × 10 −9  mol L −1 and wide linear range were obtained for chlorthiamid. • The sensor showed good stability, repeatability, and high anti-interference ability. • Good recoveries in real samples confirmed its practical use in food safety analysis. A novel surface enhanced Raman scattering (SERS) substrate, UiO-66/Leu/Au@AgNPs, was fabricated by assembling gold@silver core-shell nanoparticles (Au@AgNPs) with leucine (Leu) and the zirconium-based metal-organic framework (MOF) (UiO-66). Various techniques including SEM, TEM, HAADF-STEM, XRD, XPS, FT-IR, TGA, UV–Vis, and Zeta potential were employed to fully characterize the substrate of UiO-66/Leu/Au@AgNPs. The substrate of UiO-66/Leu/Au@AgNPs achieved remarkable Raman signal amplification for chlorthiamid. Both electromagnetic enhancement (EM) and chemical enhancement (CM) mechanisms significantly boosted the distinct and reproducible Raman signal of chlorthiamid. The determination of chlorthiamide was not interfered by fourteen types of pesticides and several common metal ions, demonstrating the good selectivity of this method. The linear regression equation was expressed as I SERS   =  128.08 c +  288,613.27 ( R 2  = 0.9982), The linear range spanned three orders of magnitude (from 3 × 10 −9 to 1 × 10 −6  mol L −1 ). A low limit of detection (LOD) of 1.95 × 10 −9  mol L −1 was obtained. The proposed method was further utilized for the determination of chlorthiamid in real samples, giving recoveries between 96.4% and 105% ( n  = 5). Download: Download high-res image (118KB) Download: Download full-size image