Liposome

A liposome is an artificially produced tiny vesicle that has the form of a sphere and contains at least one lipid bilayer. Liposomes can be used as drug delivery vehicles for the administration of pharmaceutical drugs and nutrients, such as lipid nanoparticles in mRNA vaccines and DNA vaccines. This is possible due to the liposomes' hydrophobicity and/or hydrophilicity, biocompatibility, particle size, and many other properties. Liposomes may be made by rupturing the biological membranes that surround cells (such as by sonication).

Phospholipids, particularly phosphatidylcholine and cholesterol, make up the majority of a liposome's composition. However, liposomes may also include other lipids, such as egg or phosphatidylethanolamine, as long as these components are compatible with the structure of a lipid bilayer. To adhere to diseased tissue, a liposome design may make use of surface ligands.

The four most common varieties of liposomes are the multilamellar vesicle (MLV), the small unilamellar liposome vesicle (SUV), the large unilamellar vesicle (LUV), and the cochleate vesicle. The MLV is comprised of numerous lamellar phase lipid bilayers, whereas the SUV and LUV each contain just one. The type of liposomes known as multivesicular liposomes, in which one larger vesicle includes one or more tiny vesicles, is one of the less desired forms.

It is important to differentiate between liposomes and lysosomes, as well as between micelles and reverse micelles formed of monolayers.