[Triple interpolyelectrolyte complexes DNA-polycation-polyanion: a new approach to optimization of mixtures for...

A new approach to optimization of mixtures for the condensation and introduction of plasmid DNA into eukaryotic cells is proposed, which is based on the formation of ternary interpolyelectrolyte complexes (IPEC) DNA/polycation/polyanion. Polyethyleneimine (PEI) with M 30-40 kDa as polycation and polyacrylic acid (PA) with M 20 kDa or its grafted copolymer with polyethyleneglycol (PEG) as polyanion were used, and ternary complexes with various ratios of the components were prepared. The PA-PEG incorporation into a ternary complex (by itself or as a 1:1 mixture with PA) was shown to confer the solubility onto complexes in a wide range of DNA/PEI ratios. Incorporation of even minute amounts of PA-PEG (as a 1:9 mixture with PA), while not completely preventing the aggregation of ternary IPEC, drastically changed their sorption characteristics. Using a beta-galactosidase-encoding plasmid, efficiencies of transfection of the CHO-AA8 and 293 cells for different IPEC and DNA/lipofectin complex were compared. The maximum efficiency was exhibited by ternary complex DNA/PEI/polyanion where a 1:1 mixture of PA and PA-PEG was used as polyanion. Possible reasons for this effect and further ways of optimization of mixtures for expression of plasmid DNA in the context of the new approach are discussed.