Core size optimized silver coated gold nanoparticles for rapid screening of tricyclazole and thiram residues in pear extracts using SERS

Silver-coated gold nanoparticles (Au@AgNPs) were optimized with different gold (Au) core sizes and modified surface with mercaptooctane (MCO) to determine fungicide residues in pear fruit extracts. The developed MCO/Au@AgNPs with a gold core size of 28 nm and silver shell thickness of 6 nm exhibited high sensitivity and significant enhancement of Raman scattering in detecting tricyclazole (TCZ) and thiram fungicides in standard and pear fruit samples. The detection limits for TCZ and thiram in the pear fruit extracts were 0.005 and 0.003 ppm with coefficients of determination of (R 2 ) of 0.9984 and 0.9971, percent recovery ranging from 82.7 to 107.4% and 80.7 to 109.8%, and relative standard deviation (RSD) of 1.5 to 7.9% and 3.7 to 9.5%, respectively. Results showed that this easily prepared method could be employed as SERS active platforms for the rapid assessment of trace contaminants of agrochemicals in agriculture production.