Design of biotin-functionalized luminescent quantum dots

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. Copyright © 2007 Kimihiro Susumu et al.