ausblenden:
Schlagwörter:
Lipid vesicle; Internal volume; Dynamic light scattering
Zusammenfassung:
The total internal volume, enclosed by the spherical, unilamellar membranes of a lipid vesicle dispersion, is calculated from the vesicle's size distribution according to the relationships derived here. The size distribution of phosphatidylcholine vesicles is determined from dynamic light scattering measurements. Mean vesicle radii of about 100 nm and rather symmetric distributions with standard deviations of about 25 nm are characteristic of vesicles being prepared by dialysis of mixed octyle glucoside/egg yolk phosphatidylcholine micelles. A total internal volume of about 6 ml per mmol of phospholipid has been determined from the dynamic light scattering data. This is in good agreement with the results obtained from determinations of the amount of 5(6)-carboxyfluorescein trapped by the vesicles employing absorption- and fluorescence spectroscopy, belonging to the hitherto commonly used methods. In addition, the new procedure is applied to determine the density distribution of the volume enclosed by the vesicles of a given radius as well as the number density distribution of vesicles of a given internal volume, required for a detailed interpretation of flux measurements. The latter distribution with standard deviations around 3 · 106 nm3 is rather unsymmetric with respect to the corresponding mean value of the internal volume enclosed by a single vesicle, which is here typically about 4 · 106 nm3.
