[In vitro study on polyethylene glycol-chitosan copolymer as a gene delivery vector]

Chitosan and its derivatives are extensively studied as non-viral gene delivery vectors nowadays. Polyethylene glycol-chitosan (mPEG-CS) copolymers were synthesized by oxidation of mPEG-OH and then combined mPEG-CHO with amino groups on chitosan chains. The in vitro cytotoxicity of copolymers was evaluated by MTT method. The results showed > 70% cell viability of HeLa and A549 cells after incubation with mPEG-CS copolymer from concentration 5 to 100 microg x mL(-1). The mPEG-CS copolymers with various degrees of PEG substitution were combined with DNA and the properties of mPEG-CS/DNA complexes were investigated such as nanoparticle size, zeta potential and agarose gel analysis. The best one among all these mPEG-CS copolymers was mPEG (3.55) -CS, for its capability to condense plasmid DNA was most efficient. For this reason, mPEG (3.55) -CS was picked out to mediate plasmid enhanced green fluorescence protein (pEGFP) and transfect HeLa and A549 cells. The expression of green fluorescence protein was observed by fluorescence microscope and the transfection efficiency was detected by flow cytometry. The gene expression mediated by mPEG-CS was resistant to serum, and the optimal transfection efficiency (8.1% for HeLa cells and 4.8% for A549 cells) of mPEG-CS/EGFP system was obtained under the condition of N/P 40 and 48 h transfection time. These results indicate that mPEG-CS copolymer is an efficient non-viral gene vector.