| Abstract
| - We report on the physical and optical characterization of liposomes formed by extrusion and sonication, two widelyused methods for vesicle preparation. We also address the issue of whether the properties of bilayers formed fromliposomes prepared by the two techniques differ at the molecular and mesoscopic levels. We used the phospholipid1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), with and without cholesterol, to form liposomes, incorporating1-oleoyl-2-[12-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]dodecanoyl]-sn-glycero-3-phosphocholine (18:1-12:0 NBD-PC) as an optical probe of dynamics. We measured the physical morphology of liposomes by transmission electronmicroscopy (TEM) and dynamic light scattering (DLS), and the rotational and translational diffusion of 18:1-12:0NBD-PC by time correlated single photon counting (TCSPC) and fluorescence recovery after pattern photobleaching(FRAPP), respectively. We find that, despite apparent differences in average size and size distribution, both methodsof preparation produced liposomes that exhibit the same molecular scale environment. The translational diffusionbehavior of the tethered chromophore in planar bilayer lipid membranes formed from the two types of liposomes alsoyielded similar results.
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