Ag@ZIF-67 nanocomposites for ultra-sensitive SERS detection to thiram molecules

Surface-enhanced Raman scattering technique has become a powerful tool for detecting trace targets in the field of food-safety. However, it is a challenge to regulate the hot spots of the detection substrate and its interaction with target molecules for the enhancement of SERS activity. Herein, we reported the high performance SERS substrate based on Ag@ZIF-67 nanocomposite with sugar-coated haws like structure. It was found that the coverage of ZIF-67 particles on the surface of Ag nanowires can adjust the SERS ability of detection substrate. Compared with pure Ag nanowires, functionalized Ag nanowires exhibit outstanding SERS activity with good stability and uniformity. The detection limit of crystal violet and thiram can be as low as 10−10 M and 10−8 M, respectively. After 35 d, the SERS activity remains basically unchanged. Furthermore, it also has excellent SERS response to 5 \times 10−5 M thiram residues on the surface of vegetables. Such high SERS activity can be attributed to the enrichment and screening molecular effect of porous ZIF-67 nanoparticles, and the surface plasmon resonance effect of Ag nanowires. This work provides a simple strategy for the on-site detection of pesticide residues in the actual applications.