Highly durable graphene-mediated surface enhanced Raman scattering (G-SERS) nanocomposites for molecular detection

Abstract

Graphene oxide – silver nanoparticle composites (GO-Ag) have been developed as a stable Raman sensing system. The Ag loading and concentration of GO-Ag dispersion have been optimized as a function of the Raman response. The silver nanoparticles (Ag NPs) have been well dispersed and anchored to the GO surface. The system has shown an excellent enhancement of the Raman scattering when tested with rhodamine 6G, with a 7.8-fold increase in comparison to bare Ag NPs, and a rhodamine 6G detection limit lower than 10−9 M. The sensing platform has been also tested onto a commercial pesticide, paraoxon, used to evaluate the molecular sensing capabilities in a real water solution, and its detection limit for the GO-Ag sensing substrate has been found to be as low as 10−6 M.The GO-Ag nanocomposites have shown an enhanced durability with respect to the bare Ag plasmonic nanoparticles. After being stored in a closed vessel for 180 days, the Raman intensity of rhodamine 6G measured using Ag NPs as SERS-active substrate drops to 5.2% of the initial value while in the GO-Ag system keeps a 89% efficiency with respect to the as prepared samples. The long-term stability of the system represents a significant improvement to develop SERS-active platforms based on Ag NPs.