1. Significant FRET between SWNT/DNA and rare earth ions: a signature of their spatial correlations
- Author
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Aleksandr Ryasnyanskiy, Slava V. Rotkin, Hikmat Najafov, Ming Zheng, Tetyana Ignatova, and Ivan Biaggio
- Subjects
Models, Molecular ,Photoluminescence ,Nanotubes ,Time Factors ,General Engineering ,Analytical chemistry ,Molecular Conformation ,General Physics and Astronomy ,DNA ,Acceptor ,Ion ,Solutions ,chemistry.chemical_compound ,Förster resonance energy transfer ,chemistry ,Europium ,Rare earth ions ,Calibration ,Fluorescence Resonance Energy Transfer ,General Materials Science ,Time-resolved spectroscopy ,Terbium ,Excitation - Abstract
Significant acceleration of the photoluminescence (PL) decay rate was observed in water solutions of two rare earth ions (REIs), Tb and Eu. We propose that the time-resolved PL spectroscopy data are explained by a fluorescence resonance energy transfer (FRET) between the REIs. FRET was directly confirmed by detecting the induced PL of the energy acceptor, Eu ion, under the PL excitation of the donor ion, Tb, with FRET efficiency reaching 7% in the most saturated solution, where the distance between the unlike REIs is the shortest. Using this as a calibration experiment, a comparable FRET was measured in the mixed solution of REIs with single-wall nanotubes (SWNTs) wrapped with DNA. From the FRET efficiency of 10% and 7% for Tb and Eu, respectively, the characteristic distance between the REI and SWNT/DNA was obtained as 15.9 ± 1.3 A, suggesting that the complexes are formed because of Coulomb attraction between the REI and the ionized phosphate groups of the DNA.
- Published
- 2011