Polyethylenimine-grafted polyamidoamine conjugates for gene delivery with high efficiency and low cytotoxicity

Hyperbranched polymers, polyamidoamine-methyl acrylate-polyethylenimine-ethylenediamine (PMPE) conjugates, were synthesized as a novel non-viral gene carrier based on polyamidoamine. These PMPE derivatives exhibit high transfection efficiency and low cytotoxicity. We linked methyl acrylate (MA) on polyamidoamine (PAMAM) and grafted PEI onto the PAMAM-MA, and then grafted ethylenediamine (EDA) onto the PAMAM-MA-PEI. Four polymers, PAMAM G2-MA-PEI 800-EDA, PAMAM G3-MA-PEI 800-EDA and PAMAM G2-MA-PEI 2000-EDA, PAMAM G3-MA-PEI 2000-EDA, were synthesized and characterized by H-1 NMR. PMPE was shown to interact with and condense plasmid DNA effectively to form 149-220 nm polyplexes with 34-43 mV of zeta potentials at weight ratio as 4:1 (polymer/plasmid DNA). Cytotoxicity of PMPE/pDNA complexes was lower than that of polyethylenimine (PEI) 25 kDa/pDNA complexes for all concentration ranges. In 293 and HeLa cells, PMPE/pDNA complexes showed much higher gene transfection efficiency than PAMAM. These results suggested that PMPE is an attractive novel vector for non-viral gene delivery system.