Surface enhanced fluorescence potential of ZnO nanoparticles and gold decorated ZnO nanostructures embedded in a polyvinyl alcohol matrix

Abstract

In this paper we report on the development of ZnO nanostructures based platforms for surface enhanced fluorescence emission. ZnO nanoparticles were prepared using a simple, low-cost chemical precipitation method and were decorated with Au nanoparticles following a controlled chemical synthesis. Nanostructures suspended in water and incorporated in a polyvinyl alcohol (PVA) matrix were used to design Rhodamine 6G-containing films by a simple drop-coating method. The PVA environment hindered the aggregation of the nanostructures yielding improved film formation capability. Surface enhanced fluorescence emission of Rhodamine 6G was obtained in the presence of ZnO nanoparticles embedded in the PVA matrix. The enhancement depended on the concentration of both the fluorophore and the ZnO nanoparticles. No fluorescence enhancement was observed in the case of Au decorated ZnO nanocomposites and both types of nanostructures exhibited fluorescence quenching of the dye outside of the PVA environment. Time-resolved fluorescence investigations revealed that in the presence of PVA neither the ZnO NPs nor the Au decorated ZnO nanocomposites modified the dye’s lifetime. In the absence of the PVA matrix, however, an additional decay pathway emerged, leading to modified fluorescence lifetime.