Properties of liposomes prepared with various lipids

Use of several lipids as an alternative to cholesterol to prepare stable liposomes was tried. Liposome prepared at 1/0.25 lecithin/stearic acid ratio exhibited better (55%) encapsulation efficiency (EE) of bovine serum albumin (BSA) than that (41%) prepared at 1/0.25 lecithin/cholesterol ratio. Liposomes showed the minimal released percentage of encapsulated BSA at pH 6. Storage at -20 degreesC caused serious damage to liposomes. Addition of alpha-tocopherol was effective in stabilizing liposomes. Liposomes, incorporated with alpha-amylase, prepared at 1/0.25 lecithin/cholesterol or stearic acid ratio were effective in protecting enzyme against acid (pH 2.8) and pepsin (15 mg/mL). Use of stearic acid, instead of cholesterol, would be feasible in preparing stable liposomes.