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Multistep Energy Transfer in Single Molecular Photonic Wires

2004; American Chemical Society; Volume: 126; Issue: 21 Linguagem: Inglês

10.1021/ja049351u

1943-2984

Mike Heilemann, Philip Tinnefeld, Gabriel Sanchez Mosteiro, M.F. Garcia Parajo, N.F. van Hulst, Markus Sauer,

Advanced biosensing and bioanalysis techniques

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 ∼90% across a distance of 13.6 nm and a spectral range of ∼200 nm. Fluorescence trajectories of individual photonic wires show five different fluorescence intensity patterns which can be ascribed to successive photobleaching events.