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…