Kölchens S, Ramaswami V, Birgenheier J, Nett L, O'Brien D F
C.S. Marvel Laboratories, Department of Chemistry, University of Arizona, Tucson 85721.
Chem Phys Lipids. 1993 Apr;65(1):1-10. doi: 10.1016/0009-3084(93)90076-f.
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 particles 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 square and CONTIN, in order to select suitable models for vesicle characterization. The most consistent results were obtained with CUMULANT, non-negatively constrained least square and CONTIN. In many instances single 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 concentration on the size and size distribution of extruded vesicles was determined. Extrusion through 100-, 200- and 400-nm pore size filters produced a unimodal distribution of vesicles, with somewhat smaller diameters as the extrusion pressure increased. The larger the filter pore size, the more dependent the vesicle size was on applied pressure. The observed vesicle size was independent of the lipid concentration between 0.1 and 10 mg ml-1.
通过冷冻解冻-挤压法制备的磷脂囊泡的大小分布，采用准弹性光散射（QELS）的非扰动技术进行测定，并与已知大小的乳胶颗粒进行比较。进行多角度QELS实验，以避免由于颗粒散射函数的角度依赖性而产生的误差。通过多种数学程序，即单指数、累积量、指数采样、非负约束最小二乘法和CONTIN，对实验测定的自相关函数进行分析，以便选择合适的模型来表征囊泡。使用累积量、非负约束最小二乘法和CONTIN获得了最一致的结果。在许多情况下，单指数分析给出的结果与这些程序相当，这表明囊泡具有较窄的大小分布。确定了滤膜孔径、挤压压力和脂质浓度对挤压后囊泡大小和大小分布的影响。通过100纳米、200纳米和400纳米孔径的滤膜挤压产生了单峰分布的囊泡，随着挤压压力的增加，直径略有减小。滤膜孔径越大，囊泡大小对施加压力的依赖性就越强。观察到的囊泡大小在0.1至10毫克/毫升的脂质浓度范围内与脂质浓度无关。
