Phosphatidylcholine liposome formation

Scarpa, M., Rigo, A., Maiorino, M., Ursini, F. and Gregolis, C. (1984). Formation of a-tocopherol radical and recycling of alpha tocopherol by ascorbate during peroxidation of phosphatidylcholine liposomes. An electron paramagnetic resonance study. Biochim. Biophys. Acta 801, 215-219. 

The peptide subunit was easily incorporated into lipid bilayers of liposome, as confirmed by absorption and fluorescence spectroscopy. Formation of H-bonded transmembrane channel structure was confirmed by FT IR measurement, which suggests the formation of a tight H-bond network in phosphatidylcholine liposomes. Liposomes were first prepared to make the inside pH 6.5 and the outside pH 5.5. Then the addition of the peptide to such liposomal suspensions caused a rapid collapse of the pH gradient. The proton transport activity was comparable to that of antibiotics gramicidin A and amphotericin B. 

Abstract The formation of phosphatidylcholine liposomes loaded with proanthocyanidins isolated from grape Vitis vinifera L.) seeds was studied. Using scanning electron microscopy it was determined that the type and the size of the liposomes depend on various factors proanthocyanidin concentration and homogenization conditions (time and intensity). Rheological investigations of liposome dispersions... 

A study by Bames and co-workers of the equilibrium spreading behavior of dimyristol phosphatidylcholine (DMPC) reconciles the differences between spreading of bulk solids and dispersions of liposomes [41]. This study shows the formation of multibilayers below the monolayer at the air-water interface. An incipient phase separation, undetectable by microscopy, in DMPC-cholesterol... 

Studies of the reaction of ozone with simplified lipid systems have shown that malonaldehyde can be produced by direct ozonolysis. The use of malonaldehyde assay as an index of lipid peroxidation is therefore invalid in ozone studies. Liposomes formed from egg lecithin and prepared in aqueous media were quite resistant to ozone, but the contribution of polyconcentric spheres to this resistance has not been fully assessed. However, the bilayer configuration, with the susceptible unsaturated fatty acids shielded from ozone by the hydrophilic areas of the molecule, may be resistant. In hexane, where the fatty acid moieties are exposed, ozone reacts stoichiometrically with the double bonds. The experiments with aqueous suspensions of phosphatidylcholine gave no evidence of the formation of lipid peroxides,nor did experiments with films of fatty acids exposed to ozone. ... 

Rytomaa, M., and Kinnunen, P.KJ., 1995, Reversibility of the binding of cytochrome c to liposomes. Implications for lipid-protein interactions. /. Biol. Chem., 270 3197-3202 Salamon, Z., and Tollin, G., 1996, Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar lipid bilayer. II. Binding of cytochrome c to oxidase-containing cardiolipin /phosphatidylcholine membranes. Biophys. J., 71 858-867 Salamon, Z., and Tollin, G., 1997, Interaction ofhorse heart cytochrome c with lipid bilayer membranes effects on redox potentials. J. Bioenerg. Biomembr. 29 211-221 Scarlett, J.L., and Murphy, M.P., 1997, Release of apoptogenic proteins from the... 

The formation of liposomes [or better arsonoliposomes (ARSL)], composed solely of arsonolipids (Ars with R=lauric acid (C12) myristic acid (C14) palmitic acid (C16) and stearic acid (C18) (Fig. 1) have been used for ARSL construction), mixed or not with cholesterol (Choi) (plain ARSL), or composed of mixtures of Ars and phospholipids (as phosphatidylcholine [PC] or l,2-distearoyl- -glyceroyl-PC [DSPC]) and containing or not Choi (mixed ARSL), was not an easy task. Several liposome preparation techniques (thin-film hydration, sonication, reversed phase evaporation, etc.) were initially tested, but were not successful to form vesicles. Thereby a modification of the so called one step or bubble technique (8), in which the lipids (in powder form) are mixed at high temperature with the aqueous medium, for an extended period of time, was developed. This technique was successfiil for the preparation of arsonoliposomes (plain and mixed) (9). If followed by probe sonication, smaller vesicles (compared to those formed without any sonication [non-sonicated]) could be formed [sonicated ARSL] (9). Additionally, sonicated PEGylated ARSL (ARSL that contain polyethyleneglycol [PEG]-conjugated phospholipids in their lipid bilayers) were prepared by the same modified one-step technique followed by sonication (10). 

---