3D Hot Spots Droplets on the MoS₂/Al Hydrophobic Array Interface for SERS Quantitative and Multiplex Detection of Pesticide Residues

Abstract The practical application of surface‐enhanced Raman spectroscopy (SERS) technology for quantitative analysis still confronts the hinder of controlling the uniformity of signal and anchoring target molecules in a designed space. Herein, a facile method of devising the shrinkage of three‐dimension (3D) hot spots droplets on a hydrophobic array substrate is demonstrated for the quantitative and multiplex detection of pesticide residues by using a portable Raman spectrometer. The shrunk droplet which is consisted of the analyte solution and AgNPs sol can induce simultaneously increasing density of plasmonic hot spots and immobilizing target molecules in hot spots. Besides, the closely packed Ag nanoparticles (AgNPs) are anchored in the gaps of the MoS₂ nanosheet array, generating uniform hotspots distribution with relative standard deviation (RSD) of about 8 %. In addition, the synergetic effects between MoS₂ and AgNPs further enhance the SERS sensitivity, and thereby target molecules of 10⁻⁹ m are readily detected. Besides, the proposed strategy exhibits excellent SERS sensitivity for the analysis of pesticides down to 10⁻⁸ m. Importantly, quantitative analysis and multi‐components detection of pesticide residues on honeysuckle surface are achieved. Therefore, it is expected to be used for quantitative analysis of complex pesticide systems on real samples.