SYNTHETIC CATIONIC AMPHIPHILE FOR LIPOSOME-MEDIATED DNA TRANSFECTION WITH LESS CYTOTOXICITY

A cationic peptide amphiphile comprising an L-alanine residue interpos ed between a charged head group and a double-chain segment, N,N-dihexa decyl-N lpha-[6-(trimethylammonio)-hexanoyl]-L-alaninamide bromide (NC (5)Ala(2)C(16)), was synthesized and used to prepare sonicated liposom es. We examined the efficiency of this liposome in gene transfer accor ding to the transient expression of chloramphenicol acetyltransferase (CAT). This cationic liposome reagent facilitates efficient DNA transf ection in COS-7 cells. We determined the optimum conditions for NC(5)A la(2)C(16) liposome-mediated transfection. The optimal amounts of the amphiphile and plasmid DNA were determined to be about 100 mu g and 10 mu g per 35-mm dish, respectively. The activity of this liposome was greater than that of commercial reagents, lipofectin, and -(2,3-dioleo yloxy)propyl]-N,N,N-trimethyl-ammonium methylsulfate (DOTAP), and it w as less toxic than lipofectin and DOTAP in COS-7 cells.