Web Release Date: January 15,
A Compact Functional Quantum Dot-DNA Conjugate: Preparation, Hybridization, and Specific Label-Free DNA Detection
and
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom, Molecular Medicine, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, United Kingdom, and Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT, United Kingdom
Received November 16, 2007
In Final Form: January 2, 2008
Abstract:
In this letter, we report the preparation of a compact, functional quantum dot (QD)-DNA conjugate, where the capturing target DNA is directly and covalently coupled to the QD surface. This enables control of the separation distance between the QD donor and dye acceptor to within the range of the Förster radius. Moreover, a tri(ethylene glycol) linker is introduced to the QD surface coating to effectively eliminate the strong, nonspecific adsorption of DNA on the QD surface. As a result, this QD-DNA conjugate hybridizes specifically to its complementary DNA with a hybridization rate constant comparable to that of free DNAs in solution. We show this system is capable of specific detection of nanomolar unlabeled complimentary DNA at low DNA probe/QD copy numbers via a "signal-on" fluorescence resonance energy transfer (FRET) response.
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