The effect of size of Au-core Ag-shell nanoparticles on their enhancement of fluorescence

A simple method has been developed for homogeneous deposition of uniform Au-core Ag-shell nanoparticles on glass substrate. The method uses uniform gold colloid as seed and a silver enhancing kit to provide silver overlayer with improved fluorescence enhancement properties. Depending on size of these nanoparticles, the fluorescence of FITC-HSA monolayer deposited over the nanoparticles is either quenched, not affected or, enhanced in comparison to the control area - bare glass surface. Thus a pronounced size effect underpins the ability of these nanoparticles to enhance fluorescence. Nanostructures of appropriate size thus prepared can produce promising substrates for fluorescence enhancement. One of the outstanding advantages of this method is that such substrates are spatially homogeneous, which pave the way for application of such substrates in biotechnology and life sciences.