Development of gold nanoparticle-enhanced fluorescent nanocomposites.

A gold nanoparticle-enhanced fluorescent nanocomposite was developed. The designed nanocomposite contained a spherical gold nanoparticle core, a thin PVP coating layer, a silica spacer, and a fluorescent dye layer in the silica matrix. The dye molecules were conjugated to a polymer to be effectively doped in the nanocomposites. Different sized gold nanoparticle cores were used while the spacer thickness was varied. The function of the PVP layer in the fabrication of the nanocomposites was discussed. The fluorescence enhancement effects of the metal core size (gold nanoparticles) and the distance between the fluorescent molecules and the metal core were systematically studied. A series of control experiments were conducted to ensure the accuracy of the fluorescence enhancement measurement. The results showed that the developed nanocomposite can effectively enhance the fluorescence signal of the doped dye conjugates. An enhancement factor of 9.2 was obtained when the nanocomposite contained a 13.7 ± 1.3 nm gold nanoparticle core and a 36.6 ± 4.4 nm silica spacer. It is expected that the developed nanocomposite could be an effective model for studying various effects and the mechanism of metal-enhanced fluorescence at the nanoscale.