Multistep energy transfer in single molecular photonic wires.
We demonstrate the synthesis and spectroscopic characterization of an unidirectional photonic wire based on four highly efficient fluorescence energy-transfer steps (FRET) between five spectrally different chromophores covalently attached to double-stranded DNA. The DNA-based modular conception enables the introduction of various chromophores at well-defined positions and arbitrary interchromophore distances. While ensemble fluorescence measurements show overall FRET efficiencies between 15 and 30%, single-molecule spectroscopy performed on four spectrally separated detectors easily uncovers subpopulations that exhibit overall FRET efficiencies of up to approximately 90% across a distance of 13.6 nm and a spectral range of approximately 200 nm. Fluorescence trajectories of individual photonic wires show five different fluorescence intensity patterns which can be ascribed to successive photobleaching events.
Heilemann
Mike
M
Applied Laserphysics & Laserspectroscopy, Physics Faculty, University of Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany.
Tinnefeld
Philip
P
Sanchez Mosteiro
Gabriel
G
Garcia Parajo
Maria
M
Van Hulst
Niek F
NF
Sauer
Markus
M