Constructing a highly sensitive SERS sensor based on necklace-like CNC/ZIF-8/Ag to detect and photo-degrade diquat in green tea leaves

Surface-enhanced Raman spectroscopy (SERS) has been perceived as a valuable tool in ensuring food safety due to its rapid and intuitive nature. In this study, we demonstrate a novel cellulose-ZIF-8-noble metal nanostructure as a SERS substrate for the analysis of pesticide residues in food. Cellulose nanocrystal (CNC) acting as a scaffold, we systematically integrate ZIF-8 and Ag nanoparticles to fabricate tailored necklace-like CNC/ZIF-8/Ag core/shell nanostructures. SERS analysis reveals the CNC/ZIF-8/Ag presents an high enhancement factor of 6.39 × 10 4 , a low limit of detection (LOD) of 10 −9 mol/L, and a relative standard deviation of 10.24 % across 20 substrate batches for 4-mercaptobenzoic acid, underscoring its robust sensitivity and reproducibility. Moreover, its utility extends to the quantification of diquat dibromide (DQ) in standard solutions and green tea leaves, showcasing LODs of 6.61 × 10 −9 mol/L and 6.76 × 10 −8 mol/L, respectively, thereby exhibiting promising capabilities for ultra-sensitive pesticide detection in food. The exceptional SERS property can be ascribed to the enriching properties of the porous ZIF-8 nanostructures. Significantly, when exposed to UV light, the CNC/ZIF-8/Ag nanostructures efficiently degrade DQ within 60 min. Furthermore, their practical reusability under UV light is proved by high SERS performance across five detection cycles. These results emphasize the immense potential of CNC/ZIF-8/Ag in SERS-based trace pesticide detection. • The necklace-like CNC/ZIF-8/Ag with enrichment property due to the porous ZIF-8 structure were developed. • CNC/ZIF-8/Ag nanostructures could sense DQ in green tea leaves with detection limit of 6.76 × 10 −8 M. • CNC/ZIF-8/Ag nanostructures accomplished recyclable SERS detecting DQ in 5 cycles through facile UV irradiation.