Enhanced fluorescence of graphene oxide by well-controlled Au@SiO2 core-shell nanoparticles.

Graphene and graphene derivatives, including graphene oxide (GO) and reduced GO (rGO), have attracted remarkable attention in different fields due to their unique electronic, thermal, and mechanical properties, whereas the fluorescence property is rarely been studied. This paper reports on metal-enhanced fluorescence Au@SiO2 composite nanoparticles adsorbed graphene oxide nanosheets, where the silica-shell is used to control the distance between gold-core and fluorophore GO, and a positively charged polyelectrolyte poly(allylamine hydrochloride) (PAH) is used to adsorb the negatively charged silica-shell and GO by layer-by-layer assembly (LbL) approach. The silica-shell around the 80 nm gold-core can be well-controlled by ending the reaction at different times. Various analytical techniques were applied to characterize the morphology and optical characters of the as-prepared particles. A more than three-fold increase of the fluorescence intensity of GO was obtained.