Moon M H, Giddings J C
Department of Chemistry, University of Utah, Salt Lake City 84112.
J Pharm Biomed Anal. 1993 Oct;11(10):911-20. doi: 10.1016/0731-7085(93)80049-7.
The applicability of field-low fractionation (FFF) to the characterization of liposomes is discussed and theoretically described. Because of fundamental differences in their driving forces, sedimentation FFF and flow FFF measure different vesicle properties. Sedimentation FFF, although used previously to measure vesicle sizes and size distributions, is fundamentally a technique that measures the effective mass and mass distribution of particles. It is sensitive to small changes in the effective mass of either the biomembrane or its encapsulated load and thus is likely to be useful in characterizing such properties as drug loading, biomembrane volumes and areas, and distributions of these properties. Size characterization by sedimentation FFF can only be done by deducing size from effective mass. Flow FFF, by contrast, provides a direct measurement of vesicle size and size distribution. After demonstrating the high resolution and relative accuracy of size measurement of flow FFF by the separation of polystyrene latex standards, flow FFF was applied to two preparations of DSPC-DSPA liposomes that were sonicated under different temperature conditions. Fractograms and size distributions are reported as a function of sonication time. The rapid elimination of a large diameter tail to the distribution is shown to constitute a major mechanism for distribution narrowing. Finally, results are provided bearing on the reproducibility of size distribution measurements by flow FFF.
讨论并从理论上描述了场流分级法（FFF）在脂质体表征中的适用性。由于沉降场流分级法和流动场流分级法的驱动力存在根本差异，因此它们测量的是不同的囊泡特性。沉降场流分级法虽然以前用于测量囊泡大小和大小分布，但从根本上来说是一种测量颗粒有效质量和质量分布的技术。它对生物膜或其包封物质的有效质量的微小变化很敏感，因此可能有助于表征诸如药物负载、生物膜体积和面积以及这些特性的分布等性质。通过沉降场流分级法进行尺寸表征只能通过从有效质量推导出尺寸来实现。相比之下，流动场流分级法可直接测量囊泡大小和大小分布。在用聚苯乙烯乳胶标准品进行分离以证明流动场流分级法尺寸测量的高分辨率和相对准确性之后，将流动场流分级法应用于在不同温度条件下超声处理的两种二硬脂酰磷脂酰胆碱 - 二硬脂酰磷脂酸（DSPC - DSPA）脂质体制剂。报告了破碎图和大小分布随超声处理时间的变化情况。结果表明，分布中大直径尾部的快速消除是分布变窄的主要机制。最后，给出了关于流动场流分级法尺寸分布测量重现性的结果。
