liposome (rus. липосома) — microscopic fluid-filled bubble surrounded by one or more lipid bilayer membranes.

Description

The liposome membrane is usually made of phospholipids, which constitute biological membranes: phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine providing perfect biocompatibility of liposomes. Liposomes can be created by various methods, for example, by sonication of phospholipids in water, freezing and thawing, and extrusion through filters with nano-sized pores. Lately, liposomes have been produced using supercritical fluid technology. These methods make it possible to obtain multilayered liposomes, as well as large and small single-layered liposomes. Liposome sizes may vary from several microns to tens of nanometres (nanosomes) depending on the method of their. An aqueous solution of water-soluble drug is encapsulated inside the liposomal container and a drug is administrated into the human body in such a form. It is beneficial when the active compound is toxic, e.g. anti-cancer agent, or when the drug needs to be protected from destruction on the way to the target. Nonpolar organic drug compounds are delivered to the target site inside the liposome membrane. To ensure targeted liposome delivery, targeted molecules are covalently bound to liposome surface, such as antibodies to proteins on the target cell surface. Modification with polyethylene glycol protects the liposomes from being captured by cells of the immune system, and thus increases the liposomes' lifetime in the bloodstream. Liposomes deliver drugs into a cell either by fusion with its membrane, or by endocytosis. Liposomes as nanocontainers for drugs are used in medicine for cancer treatment and also as a component of cosmetic creams.

Illustrations

Fig. 1. Liposome.
Fig. 1. Liposome.
Fig. 2. Ways of delivery of liposome contents into a cell.
Fig. 2. Ways of delivery of liposome contents into a cell.

Author

  • Shirinsky Vladimir P.

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