pH-Sensitive Vesicles Based on a Biocompatible Zwitterionic Diblock Copolymer

Highly biocompatible pH-sensitive diblock copolymer vesicles were prepared from the self-assembly of a biocompatible zwitterionic copolymer, poly[2-(methacryloyloxy)ethyl phosphorylcholine-<i>block</i>-2-(diisopropylamino)ethyl methacrylate], PMPC-<i>b</i>-PDPA. Vesicle formation occurred spontaneously by adjusting the solution pH from pH 2 to above 6, with the hydrophobic PDPA chains forming the vesicle walls. Transmission electron microscopy (TEM), dynamic laser light scattering (DLS), and UV−visible absorption spectrophotometry were used to characterize these vesicles. Gold nanoparticle-decorated vesicles were also obtained by treating the vesicles with HAuCl<sub>4</sub>, followed by NaBH<sub>4</sub>.