Abstract

Sonication of a pre-agitated aqueous solution of cationic lipid having a (EtO)3SiCH2CH2CH2 group on the quarternized ammonium nitrogen results in partially silica- or ceramic-coated liposome (cerasome), which can be used as an excellent transfection agent. Non-silylated reference lipid, which may represent cationic lipids that are used in conventional lipofection experiments, form a compact liposome, which undergoes DNA-induced fusion to provide transfection-irrelevant and larger (100–300 nm), more toxic particles. The surface-rigidified cerasome is infusible and the monomeric cerasome complex of DNA is of viral size (|[sim]|70 nm) and exhibits a remarkable transfection performance with a 102–103-fold higher efficiency (relative to the non-silylated reference lipid), minimized cytotoxicity and serum compatibility. The cerasome lipid is obtained by the reaction of 3-bromopropyltriethoxysilane with a tertiary amine derivative of the lipid. Preparation of an aqueous cerasome solution takes 1–2 h. The cerasome–DNA complex and the transfection takes about 3 d to complete.