Biotinylated glyco-functionalized quantum dots: synthesis, characterization, and cytotoxicity studies.

Quantum dots (QDs) containing surface carboxylic groups have been successfully modified using biotinylated glycopolymer and carbohydrate/biotin reagents via EDC coupling. The biotinylated glycopolymer was synthesized in controlled dimension via the reversible addition-fragmentation chain transfer (RAFT) polymerization of the three monomers containing biotin, sugar, and amine groups as pendent groups, respectively. The modified QDs were analyzed by dynamic light scattering and fluorescence spectrophotometry, and the data revealed no change in the physical properties of QDs after surface modification. Furthermore, the surface modified QDs showed excellent water solubility and colloidal stability. Subsequently, the availability of the biotin ligand on the surface of functionalized QDs was quantified using 4-hydroxyazobenzene 2-carboxylic acid (HABA)/avidin binding assay. Cell viability studies revealed that the cytotoxicity of QDs after surface functionalization is improved and that the biotinylated glycopolymer modified QDs showed an enhancement in biocompatibility as compared to that of the original QDs. The biotinylated glyco-functionalized quantum dots may act as new suitable fluorescent probes in biomedical applications.