ABSTRACT
Gene therapy and genetic engineering require reliable and efficient systems for the delivery of exogenous genes into target cells. Among nonviral vectors, cationic lipids are most widely used as a delivery vehicle for nucleic acids (1,2). In aqueous solution, cationic lipids form lamellar aggregates that, on simple mixing with diluted plasmid DNA, condense the nucleic acid into smaller multimolecular particles coated with cationic lipid bilayer. The transfection efficiency of such DNA-lipid complexes depends significantly on their ultrastructure, which in turn depends on the condensing conditions and the chemical structure of the cationic lipid (3). A number of different cationic lipids have been synthesized, and their efficiency for DNA transfer has been estimated both in vitro and in vivo (1,2). Despite some differences, all these compounds have a common structure of eukaryotic lipids in which a charged polar headgroup is connected to two hydrophobic alkyl chains. This similarity might be a significant constraint in construction of the new DNA-lipid complexes.
