Directional Photonic Wire Mediated by Homo Forster Resonance Energy Transfer on a DNA Origami Platform.
Elaborating efficient strategies and deepening the understanding of light transport at the nanoscale is of great importance for future designs of artificial light harvesting assemblies and dye based photonic circuits. In this work, we focus on studying the phenomenon of Forster resonance energy transfer (FRET) among fluorophores of the same kind (homo FRET) and its implications for energy cascades containing two or three different dye molecules. Utilizing the spatial programmability of DNA origami, we arranged a chain of cyanine 3 (Cy3) dyes flanked at one end with a dye of lower excitation energy, cyanine 5 (Cy5) with or without an additional dye of higher excitation energy, Alexa488, at the other end. We characterized the response of our fluorophore assemblies with bulk and single molecule spectroscopy and support our measurements by Monte Carlo modeling of energy transfer within the system. We find that, depending on the arrangement of the fluorophores, homo FRET between the Cy3 dyes can lead to an overall enhanced energy transfer to the acceptor fluorophore. Furthermore, we systematically analyzed the homo FRET system by addressing the fluorescence lifetime and anisotropy. Finally, we built a homo FRET mediated photonic wire capable of transferring energy through the homo FRET system from the blue donor dye (Alexa488) to the red acceptor fluorophore (Cy5) across a total distance of 16 nm.
ACS nano