Liposomes are delivery vehicles from macromolecules to cells. Within a protective coat of unilamellar vesicles consisting of phosphatidyl serine and cholesterol (1:1), they can carry DNA first to the cell membrane, and then, after fusion, to the nuclear membrane, and eventually into the nucleus. The loading of the liposomes requires DNA in a buffer and thoroughly mixed with the ether-lipid mixture. The ether is then removed. The delivery may be facilitated by polyethylene glycol, polyethyleneimine, and dimethyl sulfoxide. With appropriate coating (e.g., monoclonal antibody, DNA, viral vectors, drugs, etc.), they can be targeted to specific sites within the cell. Guanidinium-cholesterol cationic lipids (BGSC, BGTC) can be used for construction of eukaryotic vectors. Good results are obtained by the use of the cationic lipid DOTAP (dioleoyl trimethylammonium propane) and the so-called neutral helper lipid DOPE (dioleoyl phosphatidyl ethanolamine) mixtures and also with the mix of DOPC (dioleoyl phosphatidylcholine) and DOTAP. DMRIE (1,2-dimyristoyloxypropyl-3-dimethylhydroxyethyl ammonium bromide) promotes the transfer of reporter and therapeutic genes. The delivery of the DNA is quite efficient when the linear cationic lipid monolayer is transformed into hexagonal lattices. Apparently, endocytosis mediates the uptake of liposomes. The entry of the liposomal content into the nucleus is not efficient but it can be increased by four orders of magnitude if human papilloma-virus enhancer elements are incorporated into the upstream regulatory region in the plasmid replicon. Liposome vehicles can deliver very large amounts of DNA (1 Mbp) and, in contrast to viral vectors, they do not evoke an immune response. Liposomes are also used for the delivery of vaccines and drugs.  lipids,  lipids cationic,  DOGS,  fusigenic liposome,  cytofectin,  lipofection,  raft,  vaccines,  deoxyribonucleotide-gated channels,  immunoliposome,  vectors,  polyplex; Chesnoy S, Huang L 2000 Annu Rev Biophys Biomol Struct 29:27; Torchilin VP et al 2003 Proc Natl Acad Sci USA 100:1972.