A Single Molecule Polyphenylene-Vinylene Photonic Wire

Abstract

Nanoscale transport of light through single molecule systems is of fundamental importance for light harvesting, nanophotonic circuits, and for understanding photosynthesis. Studies on organization of molecular entities for directional transfer of excitation energy have focused on energy transfer cascades via multiple small molecule dyes. Here, we investigate a single molecule conjugated polymer as a photonic wire. The phenylene-vinylene-based polymer is functionalized with multiple DNA strands and immobilized on DNA origami by hybridization to a track of single-stranded staples extending from the origami structure. Donor and acceptor fluorophores are placed at specific positions along the polymer which enables energy transfer from donor to polymer, through the polymer, and from polymer to acceptor. The structure is characterized by atomic force microscopy, and the energy transfer is studied by ensemble fluorescence spectroscopy and single molecule TIRF microscopy. It is found that the polymer photonic wire is capable of transferring light over distances of 24 nm. This demonstrates the potential residing in the use of conjugated polymers for nanophotonics.

Keywords: DNA origami; Förster resonance energy transfer; conjugated polymer; nanophotonics; photonic wire; single molecule microscopy.