title: Multistep energy transfer in single molecular photonic wires.
abstract: 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.
authors.affiliation: Applied Laserphysics & Laserspectroscopy, Physics Faculty, University of Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany.
authors.forename: Mike
authors.initials: M
authors.lastname: Heilemann
authors.forename: Philip
authors.initials: P
authors.lastname: Tinnefeld
authors.forename: Gabriel
authors.initials: G
authors.lastname: Sanchez Mosteiro
authors.forename: Maria
authors.initials: M
authors.lastname: Garcia Parajo
authors.forename: Niek F
authors.initials: NF
authors.lastname: Van Hulst
authors.forename: Markus
authors.initials: M
authors.lastname: Sauer