Novel polymeric vesicles with pH-induced deformation character for advanced drug delivery.

pH-responsive amphiphilic graft macromolecules consisting of a polyphosphazene backbone, hydrophilic PEG branches and pH-sensitive DPA were successfully synthesized and characterized. The copolymer can self-assemble into vesicles in an aqueous solution with unique inner structure and homogeneously encapsulate both lipophilic and hydrophilic molecules. The pH-dependent structure change of vesicles was also observed by DLS and TEM. Dox-loaded vesicles exhibit a sharp pH-responsive drug release profile and dramatically enhance the cytotoxicity of Dox against Dox-resistant MCF-7/adr cells. These results suggest such vesicles based on pH-responsive polyphosphazene hold great potential for specific drug therapy.