Synthetic Cationic Amphiphile for Liposome-Mediated DNA Transfection with Less Cytotoxicity

Abstract

A cationic peptide amphiphile comprising an L-alanine residue interposed between a charged head group and a double-chain segment, N, N-dihexadecyl-Nα-[6-(trimethylammonio)-hexanoyl]-L-alaninamide bromide (NC₅-Ala2C₁₆), was synthesized and used to prepare sonicated liposomes. We examined the efficiency of this liposome in gene transfer according to the transient expression of chloramphenicol acetyltransferase (CAT). This cationic liposome reagent facilitates efficient DNA transfection in COS-7 cells. We determined the optimum conditions for NC₅Ala2C₁₆ liposome-mediated transfection. The optimal amounts of the amphiphile and plasmid DNA were determined to be about 100 μg and 10 μg per 35-mm dish, respectively. The activity of this liposome was greater than that of commercial reagents, lipofectin, and N-[1-(2, 3-dioleoyloxy)propyl]-N, N, N-trimethyl-ammonium methylsulfate (DOTAP), and it was less toxic than lipofectin and DOTAP in COS-7 cells.