LIPOSOMES

Definition A liposome is a spherical vesicle composed of a bilayer membrane. In biology, this specifically refers to a membrane composed of a phospholipid and cholesterol bilayer (see on the right). Liposomes can be composed of naturally-derived phospholipids with mixed lipid chains (like egg phosphatidylethanolamine), or of pure surfactant components like DOPE (dioleoylphosphatidylethanolamine). Liposomes, usually but not by definition, contain a core of aqueous solution; lipid spheres that contain no aqueous material are called micelles, however, reverse micelles [1] can be made to encompass an aqueous environment.
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microscopic, fluid-filled pouches with walls made of layers of phospholipids identical to those that make up cell membranes; used to deliver certain vaccines, enzymes, or drugs (e.g., insulin and some cancer drugs) to the body; used in the delivery of some cancer drugs to shield healthy cells from the drugsi toxicity and prevent their concentration in vulnerable tissues, lessening or eliminating common side effects; also used experimentally as a method of carrying normal genes into cells to replace defective, disease-causing genes.