Lateral diffusion of small compounds in human stratum corneum and model lipid bilayer systems
Lateral diffusion of small compounds in human stratum corneum and model lipid bilayer systems
复制标题
DOI：
10.1016/s0006-3495(96)79457-2
复制
发表时间：
1996-11-01
影响因子：
3.4
通讯作者：
Langer, RS
中科院分区：
文献类型：
--
作者：
Johnson, ME;Berk, DA;Langer, RS
采用基于图像的光漂白后荧光恢复技术（video-FRAP）测量了9种荧光探针在两种模型脂质双层体系二myristoylphosphatidylcholine （DMPC）和DMPC/cholesterol （40 mol%）以及人角质层提取脂质的横向扩散系数。这些探针都是亲脂性的，分子量从223到854 Da不等，被用来表征小化合物在这些双层体系中的横向扩散。观察到DMPC双分子层中横向扩散系数明显的分子量依赖性。数值范围从6.72 × 10（-8）到16.2 × 10(-8) cm(2)/s，较小的探针比较大的探针扩散更快。DMPC/胆固醇双分子层是该体系中最彻底的小溶质扩散表征，尽管扩散系数较低，但测量结果显示出类似的分子量依赖性，范围从1.62 x 10（-8）到5.60 x 10(-8) cm(2)/s。角质层提取脂质的横向扩散测量，代表了这种独特脂质系统中扩散的一种新方法，也显示出分子量依赖性，其值范围为0.306 x 10（-8）至2.34 x 10(-8) cm(2)/s。文献数据显示，这些强烈的分子量依赖性延伸到比本研究中检测的更小的化合物。提出了一个双参数的经验表达式，描述了溶质的分子量方面的横向扩散系数，并捕获了尺寸的依赖范围内检查。本研究阐明了在角质层提取的脂质中小分子横向扩散的程度可以通过DMPC和DMPC/胆固醇双层系统中的扩散来表示，并可能有助于更好地理解人体角质层中的小溶质运输。
An image-based technique of fluorescence recovery after photobleaching (video-FRAP) was used to measure the lateral diffusion coefficients of a series of nine fluorescent probes in two model lipid bilayer systems, dimyristoylphosphatidylcholine (DMPC) and DMPC/cholesterol (40 mol%), as well as in human stratum corneum-extracted lipids. The probes were all lipophilic, varied in molecular weight from 223 to 854 Da, and were chosen to characterize the lateral diffusion of small compounds in these bilayer systems. A clear molecular weight dependence of the lateral diffusion coefficients in DMPC bilayers was observed. Values ranged from 6.72 x 10(-8) to 16.2 x 10(-8) cm(2)/s, with the smaller probes diffusing faster than the larger ones. Measurements in DMPC/cholesterol bilayers, which represent the most thorough characterization of small-solute diffusion in this system, exhibited a similar molecular weight dependence, although the diffusion coefficients were lower, ranging from 1.62 x 10(-8) to 5.60 x 10(-8) cm(2)/s. Lateral diffusion measurements in stratum corneum-extracted lipids, which represent a novel examination of diffusion in this unique lipid system, also exhibited a molecular weight dependence, with values ranging from 0.306 x 10(-8) to 2.34 x 10(-8) cm(2)/s. Literature data showed that these strong molecular weight dependencies extend to even smaller compounds than those examined in this study. A two-parameter empirical expression is presented that describes the lateral diffusion coefficient in terms of the solute's molecular weight and captures the size dependence over the range examined. This study illustrates the degree to which small-molecule lateral diffusion in stratum corneum-extracted lipids can be represented by diffusion in DMPC and DMPC/cholesterol bilayer systems, and may lead to a better understanding of small-solute transport across human stratum corneum.