Dual-vectors of anti-cancer drugs and genes based on pH-sensitive micelles self-assembled from hybrid polypeptide copolymers

A series of amphiphilic pH-sensitive hybrid polypeptide copolymers, poly(ethylene glycol)-b-poly-(L-lysine)-b-poly(L-phenylalanine) (PEG-PLL-PLP) were synthesized. The copolymers could self-assemble into micelles with PLP as the hydrophobic core and PEG-PLL as the hydrophilic shell, as evidenced by (HNMR)-H-1 and TEM. These micelles exhibited obvious pH response in hydrodynamic diameter and pH-dependent drug release behavior, attributed to the protonation/deprotonation of amino groups in PLL segments. The copolymers could further condense plasmid DNA efficiently. Importantly, the polymer/DNA complexes showed high transfection efficiency in 293T cells under optimized conditions. This study suggested the copolymers may have great potential in both drug and gene delivery.