Solution state hybridization detection using time-resolved fluorescence anisotropy of quantum dot-DNA bioconjugates

In this Letter, we demonstrate the application of time-resolved fluorescence anisotropy measurements to detect solution state hybridization of streptavidin conjugate (CdSe) ZnS quantum dots (QD). The study was performed on samples containing 10 nM QD incubated with 800 nM DNA. We show that the rotational correlation time of QD-DNA constructs increases significantly upon hybridization with values of 330 ns (QD-ssDNA) and 1.3 mu s (QD-dsDNA), corresponding to a diameter of 14 nm and 23 nm respectively. The present study opens a new modality for hybridization detection using quantum dots. (C) 2009 Elsevier B. V. All rights reserved.