Surface Charge Density Determines the Efficiency of Cationic Gemini Surfactant Based Lipofection

The efficiency of the binary liposomes composed of 1,2-dimyristoyl-sn-glicero-3-phosphocoline and cationic gemini surfactant. (2S,3R)-2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide as transfection vectors, were measured using the enhanced green fluorescent protein coding plasmid and COS-1 cells. Strong correlation between the transfection efficiency and lipid stoichiometry was observed. Accordingly liposomes with XSR-1„d0,50 conveyed the the enhanced green fluorescent protein coding plasmid effectively into cells. The condensation of DNA by liposomes with XSR-1>0,50 was indicated by static laser light scattering and ethidium bromide intercalation essay, whereas differential scanning calorimetry and fluorescence anisotropy of diphenylhexatriene revealed stoichiometry dependent reorganization in the headgroup region of the liposome bilayer, in alignment with our previou Langmuir-balance study. Surface charge density and the organization of positive charges appear to determine the mode of interaction of DNA with . (2S,3R)-2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide/1,2-dimyristoyl-sn-glicero-3-phosphocoline liposomes, only resulting in DNA condensation when XSR-1>0,50 . Condensation of DNA in turn seems to be required for efficient transfection.