Luminescence energy transfer using a terbium chelate: Improvements on fluorescence energy transfer

P. R. Selvin, J. E. Hearst

Research output: Contribution to journalArticlepeer-review


We extend the technique of fluorescence resonance energy transfer (FRET) by introducing a luminescent terbium chelate as a donor and an organic dye, tetramethylrhodamine, as an acceptor. The results are consistent with a Forster theory of energy transfer, provided the appropriate parameters are used. The use of lanthanide donors, in general, and this pair, in particular, has many advantages over more conventional FRET pairs, which rely solely on organic dyes. The distance at which 50% energy transfer occurs is large, 65 Å; the donor lifetime is a single exponential and long (millisecond), making lifetime measurements facile and accurate. Uncertainty in the orientation factor, which creates uncertainty in measured distances, is minimized by the donor's multiple electronic transitions and long lifetime. The sensitized emission of the acceptor can be measured with little or no interfering background, yielding a >25-fold improvement in the signal-to-background ratio over standard donor-acceptor pairs. These improvements are expected to make distances >100 Å measurable via FRET. We also report measurement of the sensitized emission lifetime, a measurement that is completely insensitive to total concentration and incomplete labeling.

Original languageEnglish (US)
Pages (from-to)10024-10028
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number21
StatePublished - Oct 11 1994
Externally publishedYes


  • Forster theory
  • europium
  • lanthanide elements
  • resonance

ASJC Scopus subject areas

  • General


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