a poly(l-lysine)-based hydrophilic star block co-polymer as a protein nanocarrier with facile encapsulation and ph-responsive release

a hydrophilic star block co-polymer was synthesized, characterized, and evaluated as a protein nanocarrier. the star block co-polymer was composed of a hyperbranched polyethylenimine (pei) core, a poly(l-lysine) (pll) inner shell, and a poly(ethylene glycol) (peg) outer shell. the model protein insulin can be rapidly and efficiently encapsulated by the synthesized polymer in aqueous phosphate buffer at physiological ph. complexation between pei–pll–b-peg and insulin was investigated using native polyacrylamide gel electrophoresis. the uptake of enhanced green fluorescent protein into ad293 cells mediated by pei–pll–b-peg was also investigated. the encapsulated insulin demonstrated sustained release at physiological ph and showed accelerated release when the ph was decreased. the insulin released from the star block co-polymer retained its chemical integrity and immunogenicity.