Abstract: A novel non-virus gene delivery vector(P-PEI) was synthesized by grafting low-molecular branched PEI(molecular weight: 1000) onto the backbone of pullulan with succinic acid as a spacer. ¹H NMR, FTIR, particle size analysis and zeta-potential measurements, TEM and gel electrophoresis were performed to characterize P-PEI and P-PEI/pDNA complexes. Gel electrophoresis retardation assay demonstrated that P-PEI can wrap pDNA with electrostatic interaction excellently even in the presence of heparin, and protect pDNA from the degradation by DNase I and serum. Compared with PEI/pDNA complexes, the P-PEI/pDNA complexes show relative lower cytotoxicity against MCF-7, HeLa and COS-7 cells, even at high N/P(up to 12.5) demonstrated by MTT assay. Flowcytometry revealed that the highest transfection efficiency for P-PEI as a delivery agent was obtained at N/P ratio of 6.25, which was comparable with that of Lipofectamine 2000, and consistent with the results of luciferase expression. These results suggest that the pullulan-grafted branched polyethylenimine polymer (P-PEI) might be an excellent biocompatible candidate for gene delivery systems.

Key words: Pullulan, Polyethylenimine, Expression plasmid for green fluorescent portein pGFP, Non-virus gene vector