Vesicle small unilamellar

Sonication of MLV dispersions above the Tc of the lipids results in the formation of SUV (Saunders, et al., 1962). Sonication can be performed with a bath sonicator (Papahadjopoulos and Watkins, 1967) or a probe sonicator (Huang, 1969). During sonication the MLV structure is broken down and small unilamellar vesicles with a high radius of curvature are formed. In case of SUV with diameters of about 20 nm (maximum radius of curvature), the outer monolayer can contain over 50% of the phospholipids and in the case of lipid... 

A French pressure cell can be used to reduce the size of MLV by extrusion under high pressure. Four extrusions of egg PC-MLV at 4°C resulted in the formation of small unilamellar vesicles 94% of the lipid was found in 31- to 52-nm vesicles (Barenholz et al., 1979). 

Gainesis N., and Hauser, H. (1983). Characterization of small unilamellar vesicles produced in unsonicated phosphatidic acid and phosphatidylcholine-phosphatidic acid dispersions by pH adjustment, Biochim. Biophys. Acta, 731. 31-39. 

Uliana, J. A., Gamble, R. C., and Baldeschwieler, J. D. (1983). Liposomal blockade of the reticuloendothelial system Improved tumor imaging with small unilamellar vesicles. Science. 220. 502-505. 

Liposomes — These are synthetic lipid vesicles consisting of one or more phospholipid bilayers they resemble cell membranes and can incorporate various active molecules. Liposomes are spherical, range in size from 0.1 to 500 pm, and are thermodynamically unstable. They are built from hydrated thin lipid films that become fluid and form spontaneously multilameUar vesicles (MLVs). Using soni-cation, freeze-thaw cycles, or mechanical energy (extrusion), MLVs are converted to small unilamellar vesicles (SUVs) with diameters in the range of 15 to 50 nm. ... 

FIG. 11 Order parameter variation along acyl chains in red cell ghosts ( ), small unilamellar vesicles of egg phosphatidylcholine (V), and paraffin oil (+), as determined by the fluorescence anisotropy decay of the w-anthroyloxy fatty acid probes. (Reprinted by permission from Ref. 12.)... 

Liposomes are formed due to the amphiphilic character of lipids which assemble into bilayers by the force of hydrophobic interaction. Similar assemblies of lipids form microspheres when neutral lipids, such as triglycerides, are dispersed with phospholipids. Liposomes are conventionally classified into three groups by their morphology, i.e., multilamellar vesicle (MLV), small unilamellar vesicle (SUV), and large unilamellar vesicle (LUV). This classification of liposomes is useful when liposomes are used as models for biomembranes. However, when liposomes are used as capsules for drugs, size and homogeneity of the liposomes are more important than the number of lamellars in a liposome. Therefore, "sized" liposomes are preferred. These are prepared by extrusion through a polycarbonate... 

Temperature 25°C, equilibrium dialysis, small unilamellar vesicles (lecithin) [381]. 

Temperature 20°C, equilibrium dialysis, small unilamellar vesicles (DOPC), 0.1 M KC1 [382]. Centrifugation method (15 min, 150,000 g), brush-border membrane vesicles [433]. 

Temperature 37°C, 0.02 M ionic strength, ultrafiltration method, small unilamellar vesicles (DMPC) [441],... 

APsuv Absorption potential measured in small unilamellar vesicles (SUV)... 

Here, APsuv is the absorption potential measured from the distribution in small unilamellar vesicles (SUV) at pH 6.8, the solubility was measured at pH 6.8 in simulated intestinal fluid, V is the volume of intestinal fluid, and dose is a mean single oral dose. Liposome partitioning is only partly correlated with octanol/water distribution. 

Fig. 9 Surface modification of cells with ssDNA-PEG-lipid. (a) Real-time monitoring of PEG-lipid incorporation into a supported lipid membrane by SPR. (r) A suspension of small unilamellar vesicles (SUV) of egg yolk lecithin (70 pg/mL) was applied to a CH3-SAM surface. A PEG-lipid solution (100 pg/mL) was then applied, (ii) Three types of PEG-lipids were compared PEG-DMPE (C14), PEG-DPPE (C16), and PEG-DSPE (C18) with acyl chains of 14, 16, and 18 carbons, respectively, (b) Confocal laser scanning microscopic image of an CCRF-CEM cell displays immobilized FITC-oligo(dA)2o hybridized to membrane-incorporated oligo(dT)20-PEG-lipid. (c) SPR sensorigrams of interaction between oligo(dA)2o-urokinase and the oligo (dT)2o-PEG-lipid incorporated into the cell surface, (i) BSA solution was applied to block nonspecific sites on the oligo(dT)20-incorporated substrate, (ii) Oligo(dA)20-urokinase (solid line) or oligo(dT)20-urokinase (dotted line) was applied...

Matthay, K.K., Heath, T.D., and Papahadjopoulos, D. (1984) Specific enhancement of drug delivery to AKR lymphoma by antibody-targeted small unilamellar vesicles. Cancer Res. 44, 1880-1886. 

Da Costa G, Mouret L, Chevance S, Le Rumeur E, Bondon A (2007) NMR of molecules interacting with lipids in small unilamellar vesicles. Eur Biophys J Biophy 36 933-942... 

Suv, small unilamellare vesicles luv, large unilamellare vesicles mlv, multilamellare vesicles mvv, multivesiculare vesicles (Fig. 4 from [1.34]). 

In model systems for bilayers, one typically considers systems which are composed of one type of phospholipid. In these systems, vesicles very often are observed. The size of vesicles may depend on their preparation history, and can vary from approximately 50 nm (small unilamellar vesicles or SUVs) up to many pm (large unilamellar or LUV). Also one may find multilamellar vesicular structures with more, and often many more than, one bilayer separating the inside from the outside. Indeed, usually it is necessary to follow special recipes to obtain unilamellar vesicles. A systematic way to produce such vesicles is to expose the systems to a series of freeze-thaw cycles [20]. In this process, the vesicles are repeatedly broken into fragments when they are deeply frozen to liquid nitrogen temperatures, but reseal to closed vesicles upon thawing. This procedure helps the equilibration process and, because well-defined vesicles form, it is now believed that such vesicles represent (close to) equilibrium structures. If this is the case then we need to understand the physics of thermodynamically stable vesicles. 

Although detailed protocols for preparation of small unilamellar vesicles (SUVs) are published [80-82], their preparation is more time-demanding and complicated. In contrast, bicelles are prepared similarly to micelles with little effort. 

The three commercially available AmB formulations differ in their morphology, their composition, and, consequently, their biological activity. AmBisome (developed by Nexstar Pharmaceuticals, commercially available from Gilead Sciences) is a true liposome formulation, consisting of small, unilamellar vesicles (9). Their small size confers a prolonged circulation time... 

Figure 3 Design of a diepitope liposomal construct. Small unilamellar liposomes (PC/PG/Chol 55/25/50 molar ratio diameter 100nm) containing 10mol% of bromo-acetyl l,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine and 10mol% of the thiol-reactive lipopeptide adjuvant anchor Pam3CysAlaGly-Mal were reacted, at 25°C successively at pH 6.5, with the T-helper epitope QYI, derivatized with a C-linker at its N-terminus, followed at pH 9.0 by the B-epitope TPE derivatized with a CG linker at its N-terminus. Abbreviations PC, phosphatidylcholine PE, phosphatidylethanolamine SUV, small unilamellar vesicles. Source From Refs. 11, 20, 21.

Both thiol-derivatized peptides were conjugated to the surface of small unilamellar vesicles (PC/PG/Chol 75/20/50 65nm dia.) containing a thiol-reactive functionalized PamsCSS anchor (11,59), i.e., an amphipathic triacylated lipopeptide chosen for its adjuvanticity, its activation of DCs... 

Entrapment of plasmid DNA and/or protein into liposomes entails the preparation of a lipid film from which multilamellar vesicles and, eventually, small unilamellar vesicles (SUVs) are produced. SUVs are then mixed with the plasmid DNA and/or protein destined for entrapment and dehydrated. The dry cake is subsequently broken up and rehydrated to generate multilamellar dehydration-rehydration vesicles (DRV) containing the plasmid DNA and/or protein. On centrifugation, liposome-entrapped vaccines are separated from nonentrapped materials. When required, the DRV are reduced in size by microfluidization in the presence or absence of nonentrapped materials or by employing an alternative method (7) of DRV production, which utilizes sucrose (see below). 

Quantitative entrapment of vaccines into small (up to about 200 nm diameter) liposomes in the absence of microfluidization (which can damage DNA and other labile materials when extensive) can be carried out by a novel one-step method (7) as follows SUVs (e.g., cationic) prepared as in section Preparation of Small Unilamellar Vesicles are mixed with sucrose to give a range of sucrose-to-lipid weight/weight ratio of 1.0 to 5.0 and the appropriate amount of plasmid DNA (e.g., 10-500 pg) and/or protein (e.g., up to 1 mg). The mixture is then rapidly frozen and subjected to dehydration by freeze-drying, followed by rehydration as in section Preparation of Vaccine-Containing Dehydration-Rehydration Vesicles. ... 

Figure 3 P NMR spectrum of SUV liposomes with 20 mol% incorporated STPP. Spectrum was taken using a VARIAN Mercury 300 NMR spectrometer, 5P as indicated in the figure. Abbreviations NMR, nuclear magnetic resonance STPP, stearyl triphenylphosphonium SVV, small unilamellar vesicle. Source From Ref 30.

Fig. 5. Types of liposomes SUV, small unilamellar vesicle LUV, large unilamellar vesicle MLV, multilamellar vesicle MW, multivesicular vesicle...

AA Agbodjan, H Bui, MG Khaledi. Study of solute partitioning in biomem-brane-mimetic pseudophases by electrokinetic chromatography dihexadecyl phosphate small unilamellar vesicles. Langmuir 17 2893-2899 (2001). 

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