Novel vesicles self-assembled from amphiphilic star-armed PEG/polypeptide hybrid copolymers for drug delivery.

A novel amphiphilic four-armed [poly(ε-benzyloxycarbonyl-L-lysine)]2-block-poly(ethylene glycol)-block-[poly(ε-benzyloxycarbonyl-L-lysine)]2 hybrid copolymer has been prepared. The cytotoxicity study shows that the copolymer has good biocompatibility with no obvious inhibition effect on cell growth. The amphiphilic copolymers could self-assemble to form vesicles in aqueous solution. DOX · HCl, as a hydrophilic drug, can be loaded into the vesicles, and then successfully internalized by human breast cancer MCF-7 cells. Importantly, the DOX-loaded vesicles show a greatly improved drug release behavior with a zero-order release at the initial stage, suggesting a great potential as the carrier of hydrophilic drugs for controlled drug delivery.