Gene transfection efficacies of novel cationic gemini lipids possessing aromatic backbone and oxyethylene spacers

Abstract

Six novel gemini cationic lipids based on aromatic backbone, bearing n-C₁₄H₂₉ or n-C₁₆H₃₃ hydrocarbon chains, differing in the length of oxyethylene type spacers -CH₂-(CH₂-O-CH₂)_m-CH₂- between each ammonium headgroups have been synthesized, where m varies from 1 to 3. Each of these lipids formed stable suspensions in aqueous media. Cationic liposomes were prepared from each of these lipids individually and as mixtures of each cationic lipid and DOPE. These were used as nonviral gene delivery agents. Transfection studies showed that among lipids bearing n-C₁₄H₂₉ chains, the transfection efficacies decreased with the increase in the length of the spacer, whereas in case of lipids bearing n-C₁₆H₃₃ chains, the transfection efficacies increased with the increase in the length of the spacer. Lipid bearing n-C₁₆H₃₃ hydrocarbon chains with a [-(CH₂-CH₂-O-CH₂-CH₂-O-CH₂-CH₂-O-CH₂-CH₂)-] spacer was found to be a potent gene transfer agent and its transfection was highly serum compatible even in the presence of 50% serum conditions.