Quantum dot-pseudopolyrotaxane supramolecules as anticancer drug delivery systems

Pseudopolyrotaxanes (Ps-PR) consisting of α-cyclodextrin rings, polyethylene glycol axes and end triazine groups were synthesized and characterized. Dissociation of the α-cyclodextrin rings from the polyethylene glycol axes was avoided by the host-guest relationship between its end triazine groups and β-cyclodextrins conjugated onto the surface of quantum dots (β-CD-graft-QDs), leading to a new type of the dynamic polyrotaxanes in which QDs play the role of stoppers noncovalently. Stability of the synthesized supramolecules was depended on the efficiency of the host-guest relationships between the end triazine groups of Ps-PR and β-CD-graft-QDs through which release of α-cyclodextrin rings from the polyethylene glycol axes was controlled.To prove the efficacy of the synthesized supramolecules as drug delivery systems (DDSs) cisplatin (Cis-Diamminedichloroplatinum (CDDP) a platinum-based chemotherapy drug) and folic acid as a tumor-recognition module were conjugated to their stoppers and they were subjected to the receptor-mediated endocytosis and release inside the cancer cells, murine colon adenocarcinoma tumor C26. Then, it was proved that these tumor-targeting DDSs are promising systems for future cancer therapy. Rate of the release of the drugs, conjugated to the functional groups of stoppers was also investigated.