The aim of the present study was to improve transfection efficiency using different combinations of cationic liposomes, linear polyethylenimine and DNA. A novel gene delivery system (lipopolyplex) was developed by premixing cationic liposomes containing cholesterol or oligoamine modified cholesterol (derivative I-III) and linear polyethyleneimines (PEIs) following addition of plasmid at three different C/P ratios. The resultant complexes were characterized for their size, zeta potential and ability of DNA condensation. Luciferase reporter gene was used for determination of transfection efficiency in Neuro2A cells. Mean particle size of prepared complexes was less than 200 nm and they showed positive surface charge. The transfection efficiency of vectors was reduced by increasing in carrier concentration/plasmid DNA ratio (C/P ratio) while gene expression of cationic liposome or PEI was increased at higher C/P ratios. Complexes composed of PEI 2.5 or 250 kDa and liposome containing derivative I had the highest transfection activity. Furthermore, non-viral vectors described in this study showed low cytotoxicity. The results show that small and large molecular weight linear PEI in combination with liposome have little toxicity and may enhance transfection efficiency.
Keywords: Cationic liposome, Cytotoxicity, Gene delivery, Lipopolyplex, Polyethylenimine, Transfection, Cholesterol derivatives, Nanostructures, Non-viral gene delivery, Nanocomplexes
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