Elasticity of vesicles assessed by electron spin resonance, electron microscopy and extrusion measurements.
Elasticity of vesicles assessed by electron spin resonance, electron microscopy and extrusion measurements.
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DOI：
10.1016/s0378-5173(01)00576-2
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发表时间：
2001-04
影响因子：
5.8
通讯作者：
B. V. D. Bergh;Philip W. Wertz;H. Junginger;J. Bouwstra
中科院分区：
文献类型：
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作者：
B. V. D. Bergh;Philip W. Wertz;H. Junginger;J. Bouwstra
囊泡的组成决定了其双层的物理状态和弹性。将脂肪酸自旋标记掺入由单链非离子表面活性剂八氧乙烯月桂酸酯（PEG-8-L）、蔗糖月桂酸酯l-595和硫酸胆固醇（CS）组成的囊泡中，以监测囊泡双层中脂质分子的局部动态特性并研究囊泡双层的弹性。使用自旋标记探针 5-、12- 和 16-doxyl 硬脂酸 (DSA) 的研究表明，当 doxyl 基团靠近头基区域时，有序参数和旋转相关时间都会增加。这些发现表明，头组区域附近膜的流动性降低。比较囊泡制剂中掺入 30 mol% 或 70 mol% 的 16-DSA，发现烷基链迁移率没有差异，正如有序参数所反映的那样。然而，当 PEG-8-L:L-595:CS 囊泡的 PEG-8-L 摩尔含量分别从 100 降低至 70 和 30 mol% 时，旋转相关时间显示从 0.38 减至 0.71 和 1.13 ns。挤出测量表明，随着 PEG-8-L 的摩尔含量从 10 mol% 增加到 90 mol%，囊泡双层的弹性增加。硫酸胆固醇的加入可稳定囊泡，从而降低弹性。增加的弹性与观察到的旋转相关时间的减少密切相关。总之，这些结果表明，当囊泡中单链非离子表面活性剂PEG-8-L的摩尔含量增加时，弹性增强并且旋转相关时间减少。增强的弹性可能有助于优化囊泡设计作为透皮应用的药物载体。
The composition of vesicles determines the physical state and elasticity of their bilayers. Fatty acid spin labels were incorporated into vesicles, composed of the single chain non-ionic surfactant octaoxyethylenelaurate-ester (PEG-8-L), the sucrose laurate-ester l-595 and cholesterol sulfate (CS) to monitor local dynamic properties of lipid molecules in vesicle bilayers and to study the elasticity of vesicle bilayers. Studies with the spin label probes 5-, 12- and 16-doxyl stearic acid (DSA) indicated that both the order parameter and the rotational correlation times increased when the doxyl group was positioned closer to the headgroup region. These findings indicate that the fluidity of membranes decreased near the headgroup region. Comparing 16-DSA incorporated in vesicle formulations with either 30 or 70 mol% showed no difference in alkyl chain mobility as was reflected by the order parameter. The rotational correlation times, however, showed a slowdown from 0.38 to 0.71 and 1.13 ns when the PEG-8-L molar content was decreased from 100 to 70 and 30 mol% for PEG-8-L:L-595:CS vesicles, respectively. Extrusion measurements indicated an increase in elasticity of vesicle bilayers as the molar content of PEG-8-L was increased from 10 to 90 mol%. Incorporation of cholesterol sulfate stabilizes vesicles and thereby, decreases the elasticity. The increased elasticity correlated excellent with a reduction in the rotational correlation times observed. In conclusion, these results demonstrate that when the molar content of the single chain non-ionic surfactant PEG-8-L in vesicles is increased the elasticity is enhanced and the rotational correlation time is reduced. The enhanced elasticity might contribute to an optimal design of vesicles as drug carriers for transdermal application.