In addition to phospholipids, the basic composition of liposomes includes cholesterol, antioxidants and surfactants. Cholesterol Cholesterol (Chol) is a commonly used lipid for preparing liposomes, which can increase the rigidity of the lipid membrane and the stability of the liposome. Cholesterol is an amphiphilic molecule with a hydroxyl polar head, and the hydrophobic part is composed of four rigid steric rings in a planar configuration connected by a flexible short hydrocarbon chain. The structure of soy sterol is similar to that of cholesterol, and it can also be used for the construction of liposomes, and its membrane stability  function is also similar to that of cholesterol. The liposome bilayer is…

Phospholipids are the basic materials composing liposomes, which also determine the liposome’s physical and chemical properties. Factors affecting the stability of liposome formulations include the phase transition temperature and electric charges associated with phospholipids, the particle size associated with the manufacturing process, and the temperature, pH, and ionic strength associated with the environment. The type and amount of phospholipids are essential for the preparation of liposomes. Classification of Phospholipids Phospholipids are divided into phosphoglycerides and sphingomyelins by structure. Glycerol phosphate (PG) is composed of a hydrophilic polar head and two hydrophobic tails. The 1st and 2nd hydroxyl groups on the glycerol skeleton are esterified with fatty acids, and the 3rd…