Plasmonic Filters Based on MoS2@Au/Ag Hybrids: Controllable Separation, Preconcentration, and Sensitive SERS Detection

In this study, plasmonic filters formed by MoS2@Au/Ag hybrids are proposed as a multifunctional analytical platform for controllable separation, preconcentration, and surface enhanced Raman spectra (SERS) detection of a complex mixture of molecules. We mainly detected the mixtures of crystal violet (CV) and congo red (CR), and Rhodamine 6G (R6G) and fluorescein isothiocyanate (FITC) molecules. Firstly, we obtained layered MoS2 films, which are indispensable for the chemical absorption and the formation of dense Au nanoparticles. Secondly, the electric field distribution of Au/Ag hybrids was simulated using COMSOL. The calculated enhancement factor (EF) was 5.49 x 10(6), which proves that dense "hotspots" were generated. Thirdly, the experimentally obtained limit of detection of R6G and FITC was 10(-11) and 10(-12) M, respectively. Notably, controllable separation and concentration of the mixture were realized by electrostatic interactions, which could be used to detect each designated molecule in the mixture. Overall, the proposed filters based on MoS2@Au/Ag hybrids exhibit immense potential as a paper-based separation, preconcentration, and sensitive SERS substrate for biological and chemical detection. (C) 2020 Elsevier B.V. All rights reserved.