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Journal of Biomedicine and Biotechnology
Volume 2007 (2007), Article ID 90651, 7 pages
http://dx.doi.org/10.1155/2007/90651
Research Article

Design of Biotin-Functionalized Luminescent Quantum Dots

1Division of Optical Sciences, U.S. Naval Research Laboratory, Washington, DC 20375, USA
2Center for Bio/Molecular Science and Engineering, U.S. Naval Research Laboratory, Washington, DC 20375, USA
3Promega Biosciences, Inc., 277 Granada Dr., San Luis Obispo, CA 93401, USA

Received 25 June 2007; Accepted 21 December 2007

Academic Editor: Marek Osinski

Copyright © 2007 Kimihiro Susumu 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.

Abstract

We report the design and synthesis of a tetraethylene glycol- (TEG-) based bidentate ligand functionalized with dihydrolipoic acid (DHLA) and biotin (DHLA—TEG—biotin) to promote biocompatibility of luminescent quantum dots (QD's). This new ligand readily binds to CdSe—ZnS core-shell QDs via surface ligand exchange. QDs capped with a mixture of DHLA and DHLA—TEG—biotin or polyethylene glycol- (PEG-) (molecular weight average 600) modified DHLA (DHLA—PEG600) and DHLA—TEG—biotin are easily dispersed in aqueous buffer solutions. In particular, homogeneous buffer solutions of QDs capped with a mixture of DHLA—PEG600 and DHLA—TEG—biotin that are stable over broad pH range have been prepared. QDs coated with mixtures of DHLA/DHLA—TEG—biotin and with DHLA—PEG600/DHLA—TEG—biotin were tested in surface binding assays and the results indicate that biotin groups on the QD surface interact specifically with NeutrAvidin-functionalized microtiter well plates.