Liposome is a small spherical vesicle that is composed of cholesterol and non-toxic phospholipids. It has one or more phospholipid bilayer membranes that have some resemblance to the structure of cell membranes. The bilayer membrane is made up of two parts. One part is made up of hydrophilic polar head groups that may be either zwitterionic or negatively charged. The second part is made up of hydrophobic hydrocarbon chains with varying chain lengths and varying degrees of unsaturation.