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Aqueous compartments enclosed by lipid bilayer membranes; liposomes are also known as lipid vesicles. Phospholipid molecules consist of an elongated nonpolar (hydrophobic) structure with a polar (hydrophilic) structure at one end. When dispersed in water, they spontaneously form bilayer membranes, also called lamellae, which are composed of two monolayer layer sheets of lipid molecules with their nonpolar (hydrophobic) surfaces facing each other and their polar (hydrophilic) surfaces facing the aqueous medium. The membranes enclose a portion of the aqueous phase much like the cell membrane which encloses the cell; in fact, the bilayer membrane is essentially a cell membrane without its protein components.

Liposomes are often used to study the characteristics of the lipid bilayer. Properties of liposomes have been characterized by a variety of techniques: molecular organization by x-ray diffraction, nuclear magnetic resonance, electron paramagnetic resonance, and Raman spectroscopy; melting behavior (that is, crystal to liquid-crystal transition) by calorimetry; net electric surface charge by microelectrophoresis; size by light scattering and electron microscopy. See Lipid

Liposomes have numerous uses as biochemical and biophysical tools: (1) as vehicles for the delivery of both water- and of oil-soluble materials to the cell; (2) as immunological adjuvants; (3) as substrates for the study of membrane properties such as rotational or translational diffusion in the plane of the membrane; and (4) as intermediates in the construction of bilayers large enough for the study of electrical properties of membranes. See Cell membranes

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
After the sixth week post infection, mice were induced by MLD-STZ and then were injected with clodronate-loaded liposomes or PBS- loaded liposomes, 3 times for a week during four weeks p.i.
Interestingly, IgG-coupled liposomes with an enhanced transmucosal transport were more immunogenic than plain liposomes given i.n.
M2 PRESSWIRE-August 2, 2019-: Creative Biostructure Provides Comprehensive Catalogue of Liposome Products
Comparing the two strategies revealed that the OBP released a quick burst of scent, while the liposomes showed a slower, controlled release.
"Intravenous administration of superoxide dismutase entrapped in long circulating liposomes: II.
The vesicular suspensions were diluted with PBS (pH: 7.4) for liposomes and 40% of the ethanol:water mixture for ethosomes before measuring particle size.
MTT assay showed that both liposomes of SPC extract and purified PC decreased the viability of ASCs.
Liposomes are nanovesicular or microvesicular drug or gene delivery systems which range in size from 0.025 to 10 [mu]m and contain a single lipid bilayer or multiple interwoven lipid bilayers.
The liposomes were characterized by mean particle size, polydispersity index, and zeta potential analyses through photon correlation spectroscopy coupled to electrophoresis on a Zetasizer instrument (Nano Series, Nano ZS, Malvern).
Liposomes. Liposomes are concentric lipid-bilayered nanocarriers comprised of an aqueous core enclosed by surfactant that can be of either natural or synthetic phospholipids.
To overcome the current limitations, we coencapsulate doxorubicin and verapamil into gold liposomes and use a ns-pulsed laser to trigger fast intracellular drug release.