Issue 1, 2011

A chelating dendritic ligand capped quantum dot: preparation, surface passivation, bioconjugation and specific DNA detection

Abstract

Herein we report the synthesis of a new chelating dendritic ligand (CDL) and its use in the preparation a compact, stable and water-soluble quantum dot (QD), and further development of specific DNA sensor. The CDL, which contains a chelative dihydrolipoic acid moiety for strong QD surface anchoring and four dendritic carboxylic acid groups, provides a stable, compact and entangled hydrophilic coating around the QD that significantly increases the stability of the resulting water-soluble QD. A CDL-capped CdSe/ZnS core/shell QD (CDL-QD) has stronger fluorescence than that capped by a monodendate single-chain thiol, 3-mercapto-propionic acid (MPA-QD). In addition, the fluorescence of the CDL-QD can be enhanced by 2.5-fold by treatments with Zn2+ or S2− ions, presumably due to effective passivation of the surface defects. This level of fluorescence enhancement obtained for the CDL-QD is much greater than that for the MPA-QD. Further, by coupling a short single-stranded DNA target to the QD via the CDL carboxylic acid group, a functional QD-DNA conjugate that can resist non-specific adsorption and hybridize quickly to its complementary DNA probe has been obtained. This functional QD-DNA conjugate is suitable for specific quantification of short, labelled complementary probes at the low DNA probe:QD copy numbers via a QD-sensitised dye fluorescence resonance energy transfer (FRET) response with 500 pM sensitivity on a conventional fluorimeter.

Graphical abstract: A chelating dendritic ligand capped quantum dot: preparation, surface passivation, bioconjugation and specific DNA detection

Article information

Article type
Paper
Submitted
02 7 2010
Accepted
09 10 2010
First published
03 11 2010

Nanoscale, 2011,3, 201-211

A chelating dendritic ligand capped quantum dot: preparation, surface passivation, bioconjugation and specific DNA detection

D. Zhou, Y. Li, E. A. H. Hall, C. Abell and D. Klenerman, Nanoscale, 2011, 3, 201 DOI: 10.1039/C0NR00462F

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