Single-Molecule Fluorescence Probes Interactions between Photoactive Protein—Silver Nanowire Conjugate and Monolayer Graphene

TL;DR

The study uses single-molecule fluorescence to explore how proteins interact with silver nanowires and graphene, revealing complex energy transfer processes at the nanoscale.

Contribution

The novel contribution is the demonstration of interplay between plasmonic enhancement and energy transfer in a hybrid nanostructure involving proteins, silver nanowires, and graphene.

Findings

Fluorescence intensities are higher when proteins are coupled with both silver nanowires and graphene compared to graphene alone.

Shorter decay times indicate energy transfer from proteins to graphene in the hybrid structure.

Monitoring single emitters in hybrid nanostructures reveals complex nanoscale interactions.

Abstract

In this work, we apply single-molecule fluorescence microscopy and spectroscopy to probe plasmon-enhanced fluorescence and Förster resonance energy transfer in a nanoscale assemblies. The structure where the interplay between these two processes was present consists of photoactive proteins conjugated with silver nanowires and deposited on a monolayer graphene. By comparing the results of continuous-wave and time-resolved fluorescence microscopy acquired for this structure with those obtained for the reference samples, where proteins were coupled with either a graphene monolayer or silver nanowires, we find clear indications of the interplay between plasmonic enhancement and the energy transfer to graphene. Namely, fluorescence intensities calculated for the structure, where proteins were coupled to graphene only, are less than for the structure playing the central role in this study, containing both silver nanowires and graphene. Conversely, decay times extracted for the latter are shorter compared to a protein—silver nanowire conjugate, pointing towards emergence of the energy transfer. Overall, the results show that monitoring the optical properties of single emitters in a precisely designed hybrid nanostructure provides an elegant way to probe even complex combination of interactions at the nanoscale.

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