Synthesis and characterization of methoxy poly(ethylene glycol)-O-chitosan-polyethylenimine for gene delivery

A novel water-soluble chitosan (CS) derivative methoxy poly(ethylene glycol)-O-chitosan-polyethylenimine (mPEG-O-CS-PEI), was synthesized. The synthesized intermediates and final product were characterized and confirmed by 1H NMR and FT-IR spectra. The particle size and zeta potential of mPEG-O-CS-PEI/DNA complexes were 65 nm and +28.5 mV at the mass ratio of 20:1, respectively. Agarose gel electrophoresis study showed strong DNA binding ability of mPEG-O-CS-PEI. The transfection of L-02 cells proved that mPEG-O-CS-PEI/plasmid was significantly less toxic than PEI 35 kDa and Lipofectin. The result of real-time quantitative PCR and GFP expression imaging showed that the transfection efficiency of mPEG-O-CS-PEI was significantly higher than PEI 35 kDa and Lipofectin in L-02 cells (P < 0.05). Therefore, mPEG-O-CS-PEI copolymer may be attractive cationic polymers for nonviral gene therapy.