Preparation of Supramolecular Graft Copolymers and the Subsequent Formation of pH-Sensitive Vesicles

A feasible methodology for the preparation of vesicles through self-assembly of supramolecular graft copolymers (SGPs) was developed. Two types of polymeric vesicles were prepared through self-assembly of two SGPs. For the first SGP, hydrophobic poly(4-vinylpyridine) (PVPy) were used as main chains, and hydrophilic poly( N -vinylpyrrolidone) with carboxylic end groups (PNVP-COOH) were grafted onto the main chains through ionic interaction between the carboxylic groups and pyridine groups. For the second SGP, hydrophobic poly(4-acrylamidobenzoic acid) (PABA) were used as main chains, and poly( N -vinylpyrrolidone) with amino end groups were grafted onto the main chains through ionic interaction between the amino groups and carboxylic groups. Both SGPs could self-assemble to form vesicles in aqueous solution. The size of the vesicles prepared from the PVPy/PNVP-COOH (or PABA/PNVP-NH 2 ) system could be controlled through modulation of the mass ratio of PVPy and PNVP-COOH (or PABA and PNVP-NH 2 ). Both 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 well-controlled by the pH of the releasing solution.