Based on the reactivity of amine groups and carboxyl groups of L-lysine and L-arginine, thermal polymerization of these two natural amino acids results in hyperbranched lysine-arginine copolymers (P-lys-argX, where X refers to the relevant molar ratio of arginine to lysine). Hyperbranched polylysine (P-lys) and two derivatives (P-lys-arg0.10 and P-lys-arg0.20) have been prepared. The arginine-rich hyperbranched polymers can interact with plasmid DNA to form nano-sized particles. The polyplexes were physicochemically analyzed by agarose gel electrophoresis, dynamic light scattering, and zeta potential measurements. Furthermore, their transfection efficiency was assessed, employing COS-7, 293T, and HeLa cell lines. It was found that P-lys showed poorly in its ability of condensation with DNA and transfection efficiency. On the other hand, arginine-rich products resulted to significant enhancement of its transfection efficiency, which is dependent on the content of arginine in the polymers, and the cell line used. P-lys-arg0.20 exhibited better transfection efficiency under all the condition studied. Besides, P-lys-arg0.20 showed lower toxicity in COS-7 cells.
Keywords: arginine; gene delivery; hyperbranched; lysine.