Fabrication of pollutant-resistance SERS imprinted sensors based on SiO2@TiO2@Ag composites for selective detection of pyrethroids in water

Abstract

As a sensitive analytical technique, surface-enhanced Raman scattering (SERS) is widely used in spectral analysis, single molecule detection and biological/chemical sensors. Noble-metal nanostructures have sensitive SERS properties and usually act as SERS substrates. Moreover, semiconductors also possess SERS properties and when the semiconductors are combined with noble metals this can not only enhance the SERS signal but also introduce additional properties. Therefore, in this investigation, SiO2@TiO2@Ag composite materials are selected as SERS substrates, which not only increase the SERS property of substrates but also introduce the property of self-cleaning under conditions of UV light. The molecularly imprinted technique (MIT) is combined with SERS in this investigation to improve the disadvantage of traditional SERS substrates having low selectivity. Molecularly imprinted polymers (MIPs) have specific adsorption properties that can enrich the templates on the surface of SiO2@TiO2@Ag composites. Importantly, the MIPs can prevent the SERS substrate being oxidized, which effectively protects the core materials. Hence, SiO2@TiO2@Ag@MIPs is synthesized based on SERS and MIT for used in pyrethroid detection. The Raman intensity and fenvalerate concentration show a good linear relationship in the FE range of 1.0–100 nmol l−1 and the detection limit is 0.2 nmol l−1. Furthermore, the SiO2@TiO2@Ag@MIPs present good selectivity and self-cleaning. This investigation provides a novel approach to pyrethroid detection.