Illustration of cross-sections of different types of liposome, categorised by size and number of phospholipid bilayers. From left to right: unilamellar (LUV), oligolamellar (OLV), multilamellar (MLV). Liposomes are artificial vesicles enclosed by a lipid bilayer. Liposome lipid bilayers are most commonly formed of phospholipids, which have a hydrophilic head (blue) and hydrophobic tails (yellow). Liposomes can be used to deliver drugs or nutrients to target cells. This is especially useful when administering toxic drugs to limit the side-effects caused.