Synthesis and DNA transfection properties of new head group modified malonic acid diamides

Malonic acid diamides with two long hydrophobic alkyl chains and a basic polar head group as a new class of non-viral gene transferring compounds have shown high transfection efficiency and moderate toxicity. Based on the results obtained with saturated and unsaturated alkyl residues new derivatives with a more complex head group structure have been synthesized. For this purpose, cationic respectively basic groups were introduced by one or two lysine residues bound via tris(aminoethyl)amine spacer to the malonic acid diamide backbone. By studying in vitro gene delivery an increase of transfection efficacy was observed when using lipids with at least one unsaturated alkyl chain. This leads to cationic lipids exhibiting comparable or even higher transfection efficacies compared to the commercially available transfection agents LipofectAmine™ and SuperFect™. Phase transitions and phase structures of selected compounds have been analyzed and discussed in terms of transfection abilities. Particle size and zeta potential of liposomes and lipoplexes were also determined.

Graphical abstractSix novel cationic lipids as transfection agents, containing a new head group structure, were synthesized and characterized. The transfection properties were tested in cell culture systems. Some of the new lipids show a good transfection efficacy combined with low cytotoxicity compared with LipofectAmine™ and Superfect™ even in absence or in presence of serum.Figure optionsDownload full-size imageDownload as PowerPoint slide