Abstract: Objective A new type of stable ternary complex was formed by mixing Lipofectamine2000 with chitosan/pDNA polyplex for delivery of plasmid DNA. Methods Morphologies of liposome/chitosan/pDNA were characterized by atomic force microscopy (AFM) in tapping model. Vectors could bind pDNA sufficiently, which can be measured by gel retarding. GFP gene expression in Hep-2 cells in vitro was imaged by inverted fluorescence microscope. Cell toxicity was evaluated by the MTT assay. Results Complex vector could combine pDNA and retard it completely. The liposome/polymer/pDNA complexes were incompacted spheroids, short rod and irregular lump of larger aggregates in structure. The transfection efficiency of the lipopolyplexes showed higher GFP gene expression than Lipofectamine2000/pDNA and CTS/pDNA controls. It was 2- to 4-fold than Liposome/pDNA control, while CTS/pDNA had nearly no expression. Chitosan reduced cell toxicity of liposome. Conclusion New ternary complex has very higher transfection potential in gene delivery.

Key words: chitosan, liposome, complex vector, gene delivery system