抄録
pH–responsive polyion complex (PIC) vesicles were prepared, that collapse under acidic conditions such as those inside a lysosome. Furthermore, at acidic conditions, cationic polymer was released from the PIC vesicles to break the lysosome membranes. Diblock copolymers (P20M167 and P20A190) composed of a charge–neutralized water–soluble poly(2–(methacryloyloxy)ethyl phosphorylcholine) (PMPC; P) block and cationic or anionic blocks were synthesized via controlled radical polymerization. Poly(3–(methacrylamidopropyl)trimethylammonium chloride) (PMAPTAC; M) and poly(sodium 6–acrylamidohexanoate) (PAaH; A) were used as the cationic and anionic blocks, respectively. While the pendant fatty acid groups in the PAaH block are ionized in basic water, the fatty acid groups are protonated in acidic water. In basic water PIC vesicles were formed with a stoichiometrically charge neutralized mixture of oppositely charged P20M167 and P20A190. At acidic conditions, the PIC vesicles collapsed, because the charge balance shifted due to protonation of the PAaH block. After collapse of the PIC vesicles, P20A190 formed micelles, while P20M167 was released as unimers. PIC vesicles can encapsulate hydrophilic non–ionic guest molecules. At acidic conditions, the PIC vesicles can release the guest molecules and P20M167. The cationic P20M167 breaks the lysosome membrane to release the guest molecules from the lysosomes to the cytoplasm.
