Trace thiabendazole in apple juice detection from β- cyclodextrin surface modified silver nanoparticles based surface enhanced Raman spectroscopy

Rapid and highly sensitive detection thiabendazole (TBZ), as an effective broad-spectrum fungicide for preservation in fruits and vegetables, has become an urgent issue due to rising food safety requirements. In this research, beta-cyclodextrin (β-CD) directly reduced and modified silver nanoparticles (β-CD-Ag NPs) with uniform average ∼ 42.5 nm diameters were synthesized from AgNO 3 solution precursor. Surface-enhanced Raman spectroscopy (SERS) performance of β-CD-Ag NPs was evaluated using crystal violet as analyte molecule. The results indicate the lowest detection limit can reach 10 -12 M, with a 9.05 × 10 7 calculated enhancement factor. The improved SERS performance can be attributed to the capture of analyte molecules from special cavity structure of β-CD, and high local surface plasma resonance (LSPR) induced electric field intensities. The lowest detection limit of β-CD-Ag NPs for standard TBZ solution can reach 47 ppb, and the relationship between Raman intensities and TBZ concentrations show well linear, which indicates possible quantitative analysis. Furthermore, the detection also presents excellent reproducibility and stability. Lowest 66 ppb TBZ in apple juice can be detected from SERS of β-CD-Ag NPs, with 92% to 128% recoveries. The absorption and Fourier transform infrared transmittance spectra confirm that the molecules capture and chemical bonding formation between TBZ and β-CD are responsible for the trace detection. This research provides a possible method for the detection of pesticide residues in food and environmental systems.