The Use of Liposomes in Enzymes and Drug Design: Liposomes Drug Delivery System

Background

Liposomes are phospholipid vesicles first described by Bangham and his coworkers who showed that aqueous suspensions of phospholipids shared many of the structural and functional properties of membranes (Bangham, Standish, & Watkins, 1965). Liposomes can be prepared by dehydrating phospholipids dissolved in organic solvent. A thin phospholipid film is then obtained producing multilamellar vesicles upon its rehydration. Extrusion is a popular method of unilamellar liposomes preparation where several passes of multilamellar liposomal suspension through small polycarbonate filter membranes yields particles having a diameter near the pore size of the filter used. Consequently, the extrusion method enables the preparation of liposomes in a range of sizes (Hope, Bally, Webb, & Cullis, 1985).

Liposomes were recommended as drug delivery systems to improve the unfavorable properties of many free drugs such as the low stability, poor solubility, rapid metabolism or inappropriate biodistribution. The amphiphilic property of phospholipids enables the liposomes to carry either hydrophilic drugs in their aqueous core or hydrophobic drugs in the lipid bilayer (Leonetti, Scarsella, Semple, Molinari, D'Angelo, Stoppacciaro, Biroccio, & Zupi, 2004). Blood can be distributed to all tissues via the vasculature, which is affected and changed during the disease process. It was evidenced that inflammation results in an early phase of vasodilation followed by increased vessel permeability. Moreover, many of the drug delivery approaches in cancer therapy take advantage of the unique pathophysiology of tumor vasculature. That is, the enhanced permeability of tumor blood vessels and the decreased rate of clearance caused by the lack of functional lymphatic vessels resulted in the increased accumulation of macromolecules in tumors after intravenous administration (Claesson-Welsh, 2015).