Liposome bilayered

Batzri, S., and Korn, E. D. (1973). Single bilayer liposomes prepared without sonication, Biochim. Biophys. Acta, 298, 1015-1019. 

Schwendener, R. A., Asanger, M., and Weder, H. G. (1981). n-Alkylglucosides as detergents for the preparation of highly homogeneous bilayer liposomes of variable sizes (60-240 (p) applying defined rates of detergent removal by dialysis, Biochem. Biophys. Res. Commun.. 100, 1055-1062. 

The binding of carotenoids within the lipid membranes has two important aspects the incorporation rate into the lipid phase and the carotenoid-lipid miscibility or rather pigment solubility in the lipid matrix. The actual incorporation rates of carotenoids into model lipid membranes depend on several factors, such as, the kind of lipid used to form the membranes, the identity of the carotenoid to be incorporated, initial carotenoid concentration, temperature of the experiment, and to a lesser extent, the technique applied to form model lipid membranes (planar lipid bilayers, liposomes obtained by vortexing, sonication, or extrusion, etc.). For example, the presence of 5 mol% of carotenoid with respect to DPPC, during the formation of multilamellar liposomes, resulted in incorporation of only 72% of the pigment, in the case of zeaxanthin, and 52% in the case of (1-carotene (Socaciu et al., 2000). A decrease in the fluidity of the liposome membranes, by addition of other... 

Perhaps the simplest solvent dispersion method is that developed by Batzri and Korn (1973). Phospholipids and other lipids to be a part of the liposomal membrane are first dissolved in ethanol. This ethanolic solution then is rapidly injected into an aqueous solution of 0.16M KC1 using a syringe, resulting in a maximum concentration of no more than 7.5 percent ethanol. Using this method, single bilayer liposomes of about 25 nm diameter can be created that are... 

Talsma [1.34] showed with phospholipon 100 H, a hydrated phosphatidyl-choline of soya beans, (Nattermann, Cologne) and dicetylphosphate (DCP) (molar ratio 10 1) from which bilayer liposomes have been produced, the influence of one CPA (I), of several CPAs (II), of the vesicle size (III), and the cooling rate (IV). In all of the following tests Tris buffer of pH 7.4 is used. 

A liposome is a spherical vesicle with a membrane composed of a phospholipid and cholesterol (less than 50%) bilayer. Liposomes can be composed of naturally derived phospholipids with mixed lipid chains (such as egg phosphatidylethanolamine) or... 

Regarding other pseudostationary phases for measurement of lipophilicity or lipophilicity-related properties (e.g., intestinal absorption, brain penetration), there are several reports on the use of vesicles such as phospholipid bilayer liposome (56-58), lysophospholipid micelle (59), DTAB/SDS vesicle (60), and double-chain synthetic surfactant vesicle (61), which are described in other chapters. 

What is the physical meaning of these data The internal radius is 3.7 mn smaller than the external one, which corresponds to the thickness of the bilayer. Liposomes with an external radius of 100 mn are made up of 336 000 lipid molecules, and in this case each compartment has an internal volume of 3.74 x 10 p,l. This means that the total internal aqueous volume in one liter of a 10 mM POPC solution is 66.9 ml, namely 6.69% of the total volume. 

Dr. Thomas drew our attention to the fact that, although biological membranes are thin in comparison to his preparations, their diffusion constants may be long. I have measured permeability coefficients (transmembrane "diffusion ) for a number of solutes for artificial phospholipid bilayers (liposomes). The values follow and are to be compared for calculated permeabilities for a solute diffusion across a comparable thickness of water. 

An alternative method for introducing a plasmid DNA vector is to use liposomes. As they are composed of aqueous vesicles surrounded by a phospholipid bilayer, liposomes allow encapsulation and transportation of many substances, both hydrophilic and lipophilic, along with the plasmid. Liposomes also allow molecules such as antibodies, proteins, and sugars to be incorporated into their surface, to target them to specific sites. Due to the structural versatility shown by these systems, the chances of effective transfection may be increased by changes in the lipid composition, which may alter the superficial charge or the vesicle size (Bramwell and Perrie, 2005). Cationic liposomes have wide applications in gene transfection. 

Fortunately, most of the perturbations that can occur in complex biological membranes upon interaction with drug molecules can be studied and simulated in vitro and quantified by available physicochemical techniques, using as a model artificial membranes (bilayers, liposomes), which are readily created. 

Liposomal formulations may also be used to deliver TLR4 agonists. Consisting of spherical vesicles formed by the self-assembly of phospholipid bilayers, liposomes are a versatile, biocompatible vaccine adjuvant formulation. The wide variety of available phospholipid molecules that are employed to make liposomes may have significant effects on the structure and biological activity of the adjuvant. 

A liposome is a spherical vesicle with a membrane composed of a phospholipids and cholesterol bilayer. Liposomes can be composed of naturally derived phospholipids with mixed lipid chains, such as egg phosphatidylethanolamine, or of pure surfactants, such as dioleolylphophtidylthanolamine. Liposomes can be made by sonicating phospholipids in water followed by extrusion. Usually, a liposome contains a core of aqueous solution, in which the hydrophilic drug substances could be dissolved. For hydrophobic substances, the drug can be dissolved into the lipid membrane. 

Phospholipid bilayers, liposomes and detergent micelles have often been used as model systems for membranes and have also proved convenient for ESR experiments. Lecithin bilayers, when prepared as films on a glass slide, are known to be formed in such a way that the lecithin molecules have their long axis perpendicular to the membrane surface. When the stearic acid derivatives (C) were incorporated into lecithin bilayers, it was found that they gave ESR spectra characteristic of... 

Schwendener BA, Asanger M, Weder HG (1981) The preparation of large bilayer liposomes controlled removal of -alkyl-glue oside detergents from hpid/detergent micelles. Biochem Biophys Res Commun 100 1055-1062... 

Liposomes are phospholipid vesicles composed of lipid bilayers enclosing an aqueous compartment. Hydrophilic molecules can be encapsulated in the aqueous spaces, and lipophilic molecules can be incorporated into the lipid bilayers. Liposomes, in addition to their use as artificial membrane systems, are used for the selective delivery of antioxidants and other therapeutic dmgs to different tissues in sufficient concentrations to be effective in ameliorating tissue injuries (Stone et al., 2002). Antioxidant liposomes containing combinations of water- and lipid-soluble antioxidants may provide a unique therapeutic strategy for mustard gas exposure because (1) the antioxidants are nontoxic and could, therefore, be used at the earliest stages of exposure (2) the liposomes themselves are composed of nontoxic, biodegradable, and reusable phospholipids ... 

Keywords Lipid bilayer Liposome Lipo-polymer Planar lipid membrane Poly(lipid) Polymerizable lipid Stabilized membrane... 

Membran systems are known to play an important role in functioning biological objects (in mass transfer processes, passive and active transport of substance, regulation of an endocellular metabolism, in bio-energetics, etc.). Unique properties of biomembranes are caused by their structure, in particular, presence of bimolecular focused layers of lipids. At the same time, one of the main disadvantages of modelling lipid membran systems (monolayers, flat bilayers, liposomes), is their low stability in time and to action of external factors. 

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