engleski

Influence of charge ratio of liposome/DNA complexes on their size after extrusion and transfection efficiency

Physico-chemical characteristics of liposome/DNA complexes influence transfection efficiency and affect each other in a very intricate way. The result of this are discrepancies in conclusions drawn about the individual influence of each one. With the aim to elucidate influence of liposome/DNA charge ratio and size on transfection efficiency and on each other, we used liposome/DNA complexes with charge ratio (+/-) in the range of 1 to 50 and extruded through membranes of 400, 200 and 100 nm. Plasmid DNA encoding green fluorescent protein was used to measure transfection efficiency by flow cytometry. Sizes of liposome/DNA complexes were measured by dynamic light scattering. Liposome size was reduced after extrusion but is mainly driven by the charge ratio and not by the size of membrane pores. Reduction of complex size at each charge ratio positively correlated with transfection efficiency. It was found that at approximately constant size of complexes increasing charge ratio promotes transfection efficiency. Cationic lipid DOTAP was used for modulation of positive charge and cytotoxicity test showed that increasing amount of DOTAP increases cytotoxicity. It can be concluded that charge ratio dictates the size of complex whereas overall size reduction and higher charge ratios promote transfection efficiency in vitro.

transfection efficiency ; liposome charge ; liposome size

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