Skip to main content

Extended fluorescence resonance energy transfer with plasmonic nanocircuits

Final Report Summary - EXTENDFRET (Extended fluorescence resonance energy transfer with plasmonic nanocircuits)

Nanophotonics has enabled several successes in controlling the fluorescence properties of single emitters. In this context, nanophotonics is highly promising to enhance the Förster fluorescence resonance energy transfer (FRET), which is one of the most popular and efficient methods to measure distance, structure, and association between molecules at the nanoscale.

Despite the huge interest raised by nanophotonics and FRET separately, it is still an open question to assess whether nanophotonics can enhance FRET. This problem involves a complex competition at the nanoscale between near-field energy transfer, photon emission and nonradiative losses. Solving this question is crucial to unlock the application of nanophotonics to enhance the FRET process broadly used in life sciences and biotechnologies.

In this project, we unambiguously demonstrate the influence of the photonic environment on the FRET rate in plasmonic nanostructures. As a significant step forward compared to earlier works, our experiments are performed at the single molecule level and monitor both the donor and the acceptor emission for a broad range of experimental conditions. Moreover, we obtain a significant enhancement of the FRET rate up to 8-fold, far above the results reported so far, and demonstrate that nanophotonics can be especially relevant to enhance FRET in the case of large donor-acceptor separations.

The significance of our work is two-fold. First, our results clearly establish that FRET can be tuned with nanophotonics, paving the way towards the nanophotonic enhancement of FRET applications, from photovoltaics, organic lighting sources and biosensing. Second, the novel observation of high FRET enhancement for large donor-acceptor separations or perpendicular orientation between donor and acceptor dipoles provides a new paradigm to investigate biochemical structures with donor-acceptor distances much beyond the classical Förster range.