ZIF-8-wrapped AgNPs modified with β-cyclodextrin for sensitive detection of thiacloprid and imidacloprid by SERS technology

The high efficient surface-enhanced Raman scatterring (SERS) methods to detect thiacloprid and imidacloprid were established using ZIF-8-wrapped Ag nanoparticles (AgNPs) modified with β-cyclodextrin (β-CD). The substrate of ZIF-8/β-CD@AgNPs was characterized by ultraviolet visible spectra (UV–vis), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The interaction between the substrate and thiacloprid/imidacloprid was also explored. The optimum measurement conditions were obtained by response surface model based on single-factor experiments. Enhancement factors (EFs) of thiacloprid and imidacloprid were respectively 2.29 × 106 and 2.60 × 106. A good linearity between the scattering intensity and the concentration of thiacloprid/imidacloprid within 3–1000 nmol L−1/6–400 nmol L−1 was established. The interference experiments indicated that the methods had good selectivity. The SERS methods were successfully applied to detect thiacloprid and imidacloprid in several vegetables samples. The recoveries ranged from 95.5 % to 105 % (n = 5). The detection limits (LODs) (S/N = 3) for thiacloprid and imidacloprid were 1.50 and 0.83 nmol L−1, respectively. [Display omitted] •A novel SERS substrate ZIF-8/β-CD@AgNPs was synthesized and adequately characterized.•Enhancement factors of three substrates for thiacloprid/imidacloprid were compared.•SERS enhancement mechanism of thiacloprid/imidacloprid was discussed.•The methods were applied to test pesticide residues in vegetable samples.