New water-soluble diblock poly(ethylene glycol)-b-dendritic poly(l-lysine) with diverse den-dritic generations were molecularly designed and synthesized with well-defined structures. The chemical structures of the diblock cationic copolymers were characterized by ¹H NMR. Furthermore, agarose gel electrophoresis and fluorescence titration assays were implemented to evaluate the plasmid DNA (pDNA) binding affinities of the synthesized new block copolymers, indicating higher DNA binding affinities of the diblock copolymers with 4 and 5 generation (PLL). Moreover, the dynamic light scattering was applied to characterize the polyplexes nanoparticles of the cationic carrier/pDNA, indicating the water-soluble PEG-b-dendritic PLL and pDNA could complex to form stable “core-shell” structure nanoparticles, and the biocompatible PEG shell could possibly decrease cytotoxicity of the complexed polyplexes nanoparticle during cell gene transfection. Therefore, these new structural diblock cationic macromolecules may be further developed as potential gene carriers with high efficacy.

Key words: PEG-b-dendritic PLL, cationic gene carrier, agarose gel electrophoresis, fluorescence titration, polyplex nanoparticles