Synthesis and micellization of block copolymer based on host–guest recognition and double disulphide linkage for intracellular drug delivery

Block copolymer CSO 2500 -β-CD-PLA 3000 and CSO 2500 -β-CD-PLA 5000 were synthesized via H-bonding-instructed double disulfide linkage and host–guest recognition between adamantane and β-cyclodextrin. Transmission electron microscopy and dynamic light scattering results further confirmed the formation of self-assembled micelles with an average size of 45 and 96 nm, and a polydispersity index of 0.178 and 0.161 for blank micelles, respectively. The copolymers CSO 2500 -β-CD-PLA 3000 and CSO 2500 -β-CD-PLA 5000 exhibited a low critical micellization concentration of 0.041 and 0.027 mg/mL, respectively, suggesting that the micelles are highly stable in dilute solution. Doxorubicin (DOX), a hydrophobic model anticancer drug, was loaded in the micelles, and the drug release can be triggered and significantly accelerated in reductive environment. The blank micelles had fairly low cytotoxicity, but the DOX-loaded micelles exhibited great proliferation inhibition against HeLa cells, which was confirmed by MTT assay. The experimental results demonstrated that these copolymeric micelles are promising carriers for the redox-responsive intracellular delivery of hydrophobic anticancer drugs. Due to the noncovalent interactions between the host and guest, which endowed supramolecular block copolymer with the ability of reversible assembling and disassembling, dual stimuli responsiveness can be expected for this novel supramolecular block copolymer CSO 2500 -β-CD-PLA 5000 favorable in efficient anticancer drug delivery.