Rapid detection of pesticide residues using a silver nanoparticles coated glass bead as nonplanar substrate for SERS sensing

Abstract

Recently, surface-enhanced Raman scattering (SERS) based on noble metal nanomaterials has attracted increasing attention due to its unique characters of the high sensitivity and the capability of chemical fingerprints recognition. The traditional SERS substrates are generally designed as a planar device. Here, we fabricated a nonplanar SERS substrate using a silver nanoparticles coated glass bead to achieve quantitative SERS measurements. Moreover, the developed substrate could be dipped into sample solution, which provided high surface area for detection and efficient transport of analyte to its surface. Unlike traditional SERS detection process of “drop-dry-measure”, the proposed sensing process of “dip-dry-measure” avoided the coffee-ring, thus led to the high uniformity of SERS signal. The utility of the designed SERS substrate was demonstrated by detecting chlorpyrifos and imidacloprid in the extract solution from apple with the limits of detection of 10 ng/mL and 50 ng/mL, respectively. The proposed non-planar SERS substrate is a promising candidate for practical application in food safety and environmental monitoring.