The analysis of serum effects on structure, size and toxicity of DDAB-DOPE and DC-Chol-DOPE lipoplexes contributes to explain their different transfection efficiency.

The effect of serum on structural properties of dimethyl-dioctadecyl-ammonium bromide (DDAB)-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) liposomes and DDAB-DOPE/DNA lipoplexes has been investigated by energy dispersive X-ray diffraction (EDXD) technique, at different cationic lipid/DNA weight ratios (rho). The role of serum on the size of lipoplexes has also been studied by dynamic light scattering. Lipoplex transfection efficiency (TE) as a function of rho, and lipoplex toxicity to C6 rat glioma cells have been evaluated in Dulbecco's Modified Eagle Medium (DMEM) with and without serum. A multi-parametric analysis concerning the role of size, structure and cytotoxicity on transfection efficiency contributes to explain the experimental observation that 3beta-[N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol (DC-Chol)-DOPE/DNA transfect C6 cells better than DDAB-DOPE/DNA lipoplexes.