Controlling two-dimensional tethered vesicle motion using an electric field: interplay of electrophoresis and electro-osmosis.
Controlling two-dimensional tethered vesicle motion using an electric field: interplay of electrophoresis and electro-osmosis.
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DOI：
10.1021/la0526277
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发表时间：
2006-02
期刊：
影响因子：
--
通讯作者：
Chiaki Yoshina-Ishii;S. Boxer
中科院分区：
文献类型：
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作者：
Chiaki Yoshina-Ishii;S. Boxer
我们最近介绍了使用DNA杂交将磷脂囊泡或蛋白脂质体拴系到流体支持的脂质双层上的方法（Yoshina-Ishii，C.;米勒，G. P的;卡夫，M。L.的;库尔，E。T.; Boxer，S. G. J. Am. 2005，127，1356-1357）。这些完整的拴系囊泡在平行于支持膜表面的两个维度上扩散。在这篇文章中，我们报告的动态响应单个拴系囊泡施加平行于双层表面的电场。囊泡通过在电渗流的方向上移动来响应场，并且这可以用于可逆地集中拴系的囊泡对抗屏障。通过向支持双层中添加增加量的带负电荷的磷脂酰丝氨酸以增加电渗，可以增加拴系囊泡的电泳迁移率。电渗透的贡献可以很好地模拟一个球连接到一个圆柱形的锚在粘性膜与带电的头基。带负电荷的束缚囊泡上的电泳力与电渗透力相反。通过增加拴系囊泡上的负电荷量，可以减缓电渗流方向上的漂移;在拴系囊泡上的高负电荷下，可以迫使电泳方向上的运动。这些力之间的平衡可以在含有带负电荷的脂质的图案化支撑双层上可视化，所述带负电荷的脂质在外部施加的电场中重组以在围栏区域内产生电荷梯度。表面的电荷梯度产生电渗流的梯度，并且携带类似量的负电荷的囊泡可以被聚焦到垂直于所施加的场的区域，在该区域中电泳通过电渗透平衡，远离畜栏边界。电场是一种有效的工具来引导和聚集束缚囊泡，并测量束缚囊泡的静电特性。
We recently introduced methods to tether phospholipid vesicles or proteoliposomes onto a fluid-supported lipid bilayer using DNA hybridization (Yoshina-Ishii, C.; Miller, G. P.; Kraft, M. L.; Kool, E. T.; Boxer, S. G. J. Am. Chem. Soc. 2005, 127, 1356-1357). These intact tethered vesicles diffuse in two dimensions parallel to the supporting membrane surface. In this article, we report the dynamic response of individual tethered vesicles to an electric field applied parallel to the bilayer surface. Vesicles respond to the field by moving in the direction of electro-osmotic flow, and this can be used to reversibly concentrate tethered vesicles against a barrier. By adding increasing amounts of negatively charged phosphatidylserine to the supporting bilayer to increase electro-osmosis, the electrophoretic mobility of the tethered vesicles can be increased. The electro-osmotic contribution can be modeled well by a sphere connected to a cylindrical anchor in a viscous membrane with charged headgroups. The electrophoretic force on the negatively charged tethered vesicles opposes the electro-osmotic force. By increasing the amount of negative charge on the tethered vesicle, drift in the direction of electro-osmotic flow can be slowed; at high negative charge on the tethered vesicle, motion can be forced in the direction of electrophoresis. The balance between these forces can be visualized on a patterned supporting bilayer containing negatively charged lipids that reorganize in an externally applied electric field to create a gradient of charge within a corralled region. The charge gradient at the surface creates a gradient of electro-osmotic flow, and vesicles carrying similar amounts of negative charge can be focused to a region perpendicular to the applied field where electrophoresis is balanced by electro-osmosis, away from the corral boundary. Electric fields are effective tools to direct tethered vesicles and concentrate them and to measure the tethered vesicle's electrostatic properties.