Liposomes

Liposomes (from Greek liposoma = fat corpuscle) are artificial, spherical particles in micrometer size, with a single or multilayer membrane. They are produced from lipid solutions in organic solvents by dispersion in the water medium.

The lipid membrane consists of concentrically arranged bilayers, usually composed of phospholipids.

A liposome may consist of one or more bilayers, in which case liposomes are called unilamellar or oligo- or multilamellar. The size of liposomes ranges from about 20 nm to several µm. Due to their structure hydrophilic active agents can be incorporated in the aqueous inner phase as well as lipophilic active agents within the bilayer membrane of the liposomes.

In pharmacology liposomes are used for the transport of drugs and other substances into the cell interior as they can easily fuse with the cell membrane and thus be internalized.

In cosmetics they are used in formulations.

Liposomes were discovered by Bangham in the 60ider of thew last century (Bangham AD et al 1961, 1974).

Bangham A D et al (1974). Preparation and use of liposomes as models of biological membranes. In Methods in Membrane Biology, (ed. E. D. Korn), pp. 1-68. New York, NY: Plenum Press.

Bangham AD et al (1964). Negative staining of phospholipids and their structure modification by surface-active agents as observed in the electron microscope. J Mol Biol 13: 238-252.

Bangham AD et al (1965) Diffusion of univalent ions across the lamellae of swollen phospholipids. J Mol Biol 13: 238-252.