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A liposome is a spherical vesicle having at least one lipid bilayer. The liposome can be used as a vehicle for administration of nutrients and pharmaceutical drugs.〔(Kimball's Biology Pages, ) "Cell Membranes."〕 Liposomes can be prepared by disrupting biological membranes (such as by sonication). Liposomes are most often composed of phospholipids, especially phosphatidylcholine, but may also include other lipids, such as egg phosphatidylethanolamine, so long as they are compatible with lipid bilayer structure. A liposome design may employ surface ligands for attaching to unhealthy tissue.〔 The major types of liposomes are the multilamellar vesicle (MLV, with several lamellar phase lipid bilayers), the small unilamellar liposome vesicle (SUV, with one lipid bilayer), the large unilamellar vesicle (LUV), and the cochleate vesicle.〔(Explanation on twst.com commercial page, cf. also Int.Patent PCT/US2008/074543 on p.4, section 0014 )〕 A less desirable form are multivesicular liposomes in which one vesicle contains one or more smaller vesicles. Liposomes should not be confused with micelles and reverse micelles composed of monolayers.〔Stryer S. (1981) Biochemistry, 213〕 ==Discovery== The word ''liposome'' derives from two Greek words: ''lipo'' ("fat") and ''soma'' ("body"); it is so named because its composition is primarily of phospholipid. Liposomes were first described by British haematologist Alec D Bangham in 1961 (published 1964), at the Babraham Institute, in Cambridge. They were discovered when Bangham and R. W. Horne were testing the institute's new electron microscope by adding negative stain to dry phospholipids. The resemblance to the plasmalemma was obvious, and the microscope pictures served as the first evidence for the cell membrane being a bilayer lipid structure. Their integrity as a closed, bilayer structure, that could release its contents after detergent treatment (structure-linked latency) was established by Bangham, Standish and Weissmann in the next year.〔Bangham, A.D., Standish, M.M. and Weissmann, G., The action of steroids and streptolysin S on the permeability of phospholipid structures to cations, J. Molecular Biol., 13:253-259, 1965〕 Weissmann - during a Cambridge pub discussion with Bangham - first named the structures "liposomes" after the lysosome, which his laboratory had been studying: a simple organelle the structure-linked latency of which could be disrupted by detergents and streptolysins.〔Sessa, G. and Weissmann, G., Incorporation of lysozyme into liposomes: A model for structure-linked latency, J. Biol. Chem., 245:3295-3301, 1970〕 Liposomes can be easily distinguished from micelles and hexagonal lipid phases by negative staining transmission electron microscopy.〔YashRoy R.C. (1990) Lamellar dispersion and phase separation of chloroplast membrane lipids by negative staining electron microscopy. Journal of Biosciences, vol 15(2), pp. 93-98.http://www.ias.ac.in/jarch/jbiosci/15/93-98.pdf〕 Alec Douglas Bangham with colleagues Jeff Watkins and Malcolm Standish wrote the 1965 paper that effectively launched the liposome “industry”. Around this time he was joined at Babraham by Gerald Weissmann, an American physician with an interest in lysosomes. Now an emeritus professor at New York University School of Medicine, Weissmann recalls the two of them sitting in a Cambridge pub and reflecting on the role of lipid sheets in separating the interior of the cell from the exterior milieu. This insight, they felt, was to cell function what the discovery of the double helix had been to genetics. Bangham had called his lipid structures “multilamellar smectic mesophases” or sometimes “Banghasomes”. It was Weissmann who proposed the more user-friendly term liposome.〔G. Weissmann, G. Sessa, M. Standish and A. D. Bangham, J. Clin. Invest., 1965, 44, 1109–1116〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Liposome」の詳細全文を読む スポンサード リンク
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