The delivery of doxorubicin of multifunctional -cyclodextrin-modified CdSe/ZnS quantum dots for bioactivity and nano-probing

The modified quantum dots (QDs) have been used in intracellular probing and drug delivery because of their special chemical and physical properties. In this paper, two -cyclodextrin (-CD)-modified CdSe/ZnS QDs with strong optical emission properties were synthesized as drug carriers to induce apoptosis. The positively charged l-Arginine (l-Arg) and neutral l-Tryptophan (l-Trp) were selected as ligands to compare the effect of charge on bioactivity of QDs nanoparticles. The in vitro assays revealed that these modified QDs showed good Dox carrier ability and significantly high inhibition rate to cancer cells. Especially, the more positively charged -CD-l-Arg-polyamine-coated CdSe/ZnS QDs could effectively deliver the doxorubicin (Dox) into cells and exhibit excellent cell selectivity in cancer versus normal cells. The Dox-loaded QDs could enter intracellular, which showed that the Dox can efficiently go through the membranes at the existence of -CD. Several lines of evidence suggest that the Dox-loaded QDs can efficiently induce apoptosis likely related to the production of ROS. We expect that the modified QDs can enhance the amount of hydrophobic antitumor drugs in cells and can also be used as fluorescent imaging agents.