MODULATION OF INTERACTION FORCES BETWEEN BILAYERS EXPOSING SHORT-CHAINED ETHYLENE-OXIDE HEADGROUPS
MODULATION OF INTERACTION FORCES BETWEEN BILAYERS EXPOSING SHORT-CHAINED ETHYLENE-OXIDE HEADGROUPS
复制标题
DOI：
10.1016/s0006-3495(94)80938-5
复制
发表时间：
1994-05-01
影响因子：
3.4
通讯作者：
ISRAELACHVILI, JN
中科院分区：
文献类型：
--
作者：
KUHL, TL;LECKBAND, DE;ISRAELACHVILI, JN
脂质体作为药物输送系统的使用受到了单核吞噬细胞系统快速清除循环的限制。最近的研究发现，通过加入少量的改性脂类，其头基是由聚氧乙烷的大量水溶性聚合链衍生而成的，可以极大地延长循环时间。我们报道了一项系统的研究，使用表面力仪器直接测量两个磷脂酰乙醇胺类脂双层之间的相互作用，暴露了双分子层中不同浓度的聚合物头基。我们发现，在所有的分离中，作用力变得相互排斥，并且空间位阻的厚度可以很容易地通过调节修饰的脂类的浓度来控制。测量的平衡力分布是可逆的，对电解液浓度和温度的变化基本不敏感。这些结果使得Dolan和Edwards关于低覆盖率聚合物表面的立体作用力的理论和Alexander de Gennes关于高覆盖率表面的理论得以测试，而且这两种理论都被发现适用。我们的结论是，这些简单的理论可以用来模拟令人惊讶的短链段的相互作用，因此，适用于这样的系统，如具有大体积头基的脂类和含有空间稳定聚合物的脂质体。
The use of liposomes as drug delivery systems has been limited by their rapid clearance from circulation by the mononuclear phagocyte system. Recent studies have found that circulation times can be greatly enhanced by incorporating a small amount of modified lipids whose headgroups are derivatized with a bulky water soluble polymeric chain of poly ethylene oxide. We report here a systematic study using the Surface Forces Apparatus to measure directly the interactions between two phosphatidyl ethanolamine lipid bilayers, exposing this polymeric headgroup at different concentrations in the bilayer. We found that the force becomes repulsive at all separations and that the thickness of the steric barrier could be controlled easily by adjusting the concentration of the modified lipids. Equilibrium force profiles were measured that were reversible and largely insensitive to changes in electrolyte concentration and temperature. The results have enabled the Dolan and Edwards theory for the steric forces of low coverage polymer surfaces and the Alexander de Gennes theory for high coverage surfaces to be tested, and both were found to apply. We conclude that these simple theories can be used to model the interactions of surprisingly short segments and, hence, apply to such systems as lipids with bulky headgroups and liposomes containing a sterically stabilizing polymer.