S. Kolchens et al., QUASI-ELASTIC LIGHT-SCATTERING DETERMINATION OF THE SIZE DISTRIBUTIONOF EXTRUDED VESICLES, Chemistry and physics of lipids, 65(1), 1993, pp. 1-10
The size distribution of phospholipid vesicles prepared by the freeze
thaw-extrusion method were determined by the non-perturbing technique
of quasi-elastic light scattering (QELS) and compared to latex particl
es of known size. Multiangle QELS experiments were performed to avoid
errors due to the angular dependence of the scattering function of the
particles. The experimentally determined autocorrelation function was
analyzed by multiple mathematical procedures, i.e. single exponential
, CUMULANT, exponential sampling, non-negatively constrained least squ
are and CONTIN, in order to select suitable models for vesicle charact
erization. The most consistent results were obtained with CUMULANT, no
n-negatively constrained least square and CONTIN. In many instances si
ngle exponential analysis gave comparable results to these procedures,
which indicates the vesicles have a narrow distribution of sizes. The
influence of filter pore size, extrusion pressure and lipid concentra
tion on the size and size distribution of extruded vesicles was determ
ined. Extrusion through 100-, 200- and 400-nm pore size filters produc
ed a unimodal distribution of vesicles, with somewhat smaller diameter
s as the extrusion pressure increased. The larger the filter pore size
, the more dependent the vesicle size was on applied pressure. The obs
erved vesicle size was independent of the lipid concentration between
0.1 and 10 mg ml-1.