Fluorescence enhancement using silver-gold nanocomposite substrates.

Metal-enhanced fluorescence (MEF) is a newly emerging phenomenon in which the near-field interactions of fluorophores with the plasmons in metallic nanostructures can lead to substantial fluorescence enhancements. In the present study, we have investigated the use of silver-gold nanocomposite (Ag-Au-NC) structures, prepared by the galvanic replacement reaction of silver with gold, as plasmonic substrates for MEF. We have observed significant enhancement in the fluorescence intensities and decrease in the fluorescence lifetimes of two commonly used dyes, ATTO655 and Cy5, using the fabricated Ag-Au-NC substrates. Interestingly, the fluorescence enhancement depends on the amount of residual silver present in the substrates after the galvanic replacement reaction. Our results show that the galvanic replacement reaction is a very facile and powerful route to prepare Ag-Au-NC substrates that can be suitable for various MEF based applications.