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Journal of Biomedicine and Biotechnology
Volume 2007, Article ID 54169, 7 pages
Research Article

Development of FRET-Based Assays in the Far-Red Using CdTe Quantum Dots

1School of Physics and Astronomy, Cardiff University, Cardiff, Wales CF24 3AA, UK
2School of Medicine, Cardiff University, Cardiff, Wales CF14 4XN, UK

Received 29 March 2007; Accepted 11 October 2007

Academic Editor: Marek Osinski

Copyright © 2007 E. Z. Chong et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Colloidal quantum dots (QDs) are now commercially available in a biofunctionalized form, and Förster resonance energy transfer (FRET) between bioconjugated dots and fluorophores within the visible range has been observed. We are particularly interested in the far-red region, as from a biological perspective there are benefits in pushing to 700 nm to minimize optical absorption (ABS) within tissue and to avoid cell autofluorescence. We report on FRET between streptavidin- (STV-) conjugated CdTe quantum dots, Qdot705-STV, with biotinylated DY731-Bio fluorophores in a donor-acceptor assay. We also highlight the changes in DY731-Bio absorptivity during the streptavidin-biotin binding process which can be attributed to the structural reorientation. For fluorescence beyond 700 nm, different alloy compositions are required for the QD core and these changes directly affect the fluorescence decay dynamics producing a marked biexponential decay with a long-lifetime component in excess of 100 nanoseconds. We compare the influence of the two QD relaxation routes upon FRET dynamics in the presence of DY731-Bio.