Proceedings Article | 14 March 2018
KEYWORDS: Plasmonics, Nanoantennas, Nanostructures, Molecules, Spectroscopy, Gold, Particles, Antennas, Quantum efficiency, Modulation, DNA nanotechnology, Directed self assembly
Short DNA strands can be used as robust and versatile templates to produce plasmonic nanostructures with a fully controlled chemical environment. They allow the parallel production of millions of copies of gold particle dimers linked by a single DNA strand with gaps that can be controlled at the nanometer scale (M. P. Busson et al, Nano Lett. 11, 5060 (2011)). In particular, fluorescent dye molecules can be easily introduced in such plasmonic antennas at the position where optical fields are strongly enhanced and confined (M. P. Busson et al, Nat. Commun. 3, 962 (2012)). In practice, the efficiency of DNA-templated optical antennas can be optimized to enhance the excitation and emission rates of single fluorescent molecules by two orders of magnitude while reaching quantum yields as high as 70 % (S. Bidault et al, ACS Nano 10, 4806 (2016)). Furthermore, by introducing two dye molecules that act as a FRET (Förster resonant energy transfer) pair, we show how field confinement in plasmonic antennas allows the modulation of non-radiative energy transfer processes (S. Bidault et al, ACS Photonics 3, 895 (2016)).
The flexibility of DNA-based self-assembly also means that the morphology of the produced nanostructures can be modulated in-situ. For example, we show how the gap between two 40 nm gold particles can be tuned, and monitored spectroscopically, between 20 nm and ~1 nm by modifying the ionic strength (L. Lermusiaux et al, ACS Nano 9, 978 (2015)), opening perspectives for the active tuning of DNA-templated plasmonic nanoantennas.
