pH-Sensitive Vesicles Prepared from Supramolecular Graft Copolymers and the Application in the Controlled Release of Drug

Supramolecular graft copolymers (SGP) were prepared via the ionic interaction between poly(4-vinylpyridine) (PVPy) and poly(N-isopropylacrylamide) with carboxylic end groups (PNIPAM-COOH). Hydrophobic PVPy was used as main chains, and hydrophilic PNIPAM-COOH grafted onto the main chains through the ionic interaction between the carboxylic groups and pyridine groups. The SGP could self-assemble to form vesicles in DMF/H(2)O system. When modulating the mass ratio of PVPy to PNIPAM-COOH from 1 to 3, the size of the vesicles could be controlled from 130 to 330 nm. These vesicles were sensitive to pH, and could be deformed by changing pH. Drug-release studies showed that release rates of the loaded drug (sunset yellow) in the two vesicles could be controlled by the pH of the solution.