Liposome fusion induced by pH-sensitive copolymer: Poly(4-vinylpyridine-co-N,N′-diethylaminoethyl methacrylate)

Copolymers of 4-vinylpyridine (4VP) or N,N′-diethylaminoethyl methacrylate (DEAEMA) were synthesized with various comonomer feed ratios (30 : 70, 50 : 50, and 70 : 30). Charge densities along the polymeric chain were changed in a pH-dependent manner. The copolymers induced membrane fusion of negatively charged liposomes followed by aggregation in a pH-dependent manner, which was investigated by resonance energy transfer. It was found that pH-dependent fusion of liposomes was dependent on the composition of 4VP and DEAEMA in the copolymer with the degree of protonation proportional to the difference in pK_a value of the two monomers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2305–2309, 1999