Water-soluble quantum dots as biological labels

Abstract

Quantum Dots are promising materials as fluorescent biological labels. Bifunctional small organic ligands are often used to coat on the surface of quantum dots to render them water-soluble. As small ligands are easily desorbed from the surface of quantum dots, the inorganic cores are subsequently labile to be destructed and further precipitate while exposing to oxidizers, acids or radiation. In order to improve their stability, we have designed and synthesized nine organic ligands through twenty-four intermediate compounds for modifying the surface of quantum dots. After these ligands were cross-linked to form a layer of polymer shell, the resultant polymer-shelled quantum dots had improved chemical, photochemical and thermal stability. Biocompatible quantum dots were also prepared by a post-synthesis modification with cyclodextrins on the basis of host-guest interactions. Optimized methods were proposed to cross-link the surface-coated ligands, including the newly synthesized cyclodextrin derivatives and their a??guesta?? organic ligands.