Biotinylated CdSe/ZnSe nanocrystals for specific fluorescent labeling

A set of two new surface ligands is presented for the preparation of water-soluble, biotinylated CdSe/ZnSe core/shell nanocrystals, suitable for fluorescent biological labeling. It consists of a thiolated diethyleneglycol derivative and an alkylthiol substituted biotin molecule, which replace the initial capping ligands at the nanocrystal surface. Successful ligand exchange and long-term photostability of the modified nanocrystals as well as their highly specific binding to neuronal cells are demonstrated in different labeling experiments.