Lipofection - The delivery of DNA into cells using liposomes is called lipofection. Liposomes are small vesicles prepared from a suitable lipid. Initially, nonionic lipids were used for preparing liposomes so that DNA had to be introduced within the vesicles following specific encapsidation procedures.

The use of cationic lipids for the construction of liposomes is a distinct advantage as DNA spontaneously and efficiently complexes with these liposomes making encapsidation procedures unnecessary.

Liposomes prepared by the above approaches are phagocytosed by the cell. The phagocytosis vesicles thus produced ordinarily fuse with lysosomes leading to DNA degradation and low transfection frequencies. The use of cationic liposomes to which DNA binds on the outside by electrostatic attraction has been quite successful.

These liposomes cause perturbations in plasma membrane due to which they fuse and the DNA enters into the cytoplasm. Cationic liposomes are available commercially (marketed as 'Lipofectin' by Gibco-BRL).

Lipofection is the method of choice for transfection of mammalian cells in vitro. It has also been used to deliver DNA into live animals by direct injection or intravenous injection.