Fluorescence modulation meditated by colloidal plasmonic metastructure

Abstract

Fluorescent materials can interact strongly with plasmonic nanostructures through coherent energy exchange. There have been various studies on this energy coupling state on the single molecular level. These studies provide great insight to understanding the coupling dynamics

however, due to the high complexity and expense of the experimental set-ups, it is challenging to translate the principles directly to the real-life applications. On the other hand, ensemble signal characterization techniques hold great popularity in biomedical sensing and imaging applications due to their simple set-ups at a moderate cost. Therefore, this study is aimed to explore the energy hybridization in the ensemble state. For this, colloidal plasmonic nanocavities have been fabricated via wet chemistry meditated self-assembly. The nanocavity was composed with two end-to-end assembled gold nanorods. The cavity size, which was controlled by thiolated single strand DNAs, was set to 11 nm. When the fluorophore, cyanine-5, was subjected to the plasmonic hot-spot at the nanocavity, the fluorescence intensity was enhanced by 7.8 folds. The result provides experimental evidence of ensemble fluorescent signal enhancement by plasmonic hot-spots in colloidal samples. Therefore, this plasmonic metastructure can be expected to provide a platform for fluorescence based biomedical sensing and imaging applications.