Tension-stabilized pores in giant vesicles: determination of pore size and pore line tension.
Tension-stabilized pores in giant vesicles: determination of pore size and pore line tension.
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DOI：
10.1016/0005-2736(93)90319-u
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发表时间：
1993-04
期刊：
影响因子：
--
通讯作者：
D. Zhelev;David C. Needham
中科院分区：
文献类型：
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作者：
D. Zhelev;David C. Needham
我们提出的第一个观察巨大的，长期存在的，稳定的泡膜孔。采用一种新的研究脂质膜电透性的实验技术，对直径为25 ~ 56 μm的巨脂质体进行了单次方波电脉冲（脉宽150 μs，场强63 ~ 126 kV/m）处理。用微量移液管保持脂质体，并通过控制移液管抽吸压力产生小的膜张力。脂质体装载有具有与外部溶液不同的折射率的介质，并且在这些条件下，加压脂质体中孔的形成可以通过从膜孔流出的内部溶液的射流来可视化。通过调节膜张力，孔保持开放，孔寿命可以从十分之一秒到几秒不等。由孔隙区域中的体积流量和跨双层测量的压力差确定孔径。从实验中可以清楚地看出，在脉冲之后只有一个孔保持打开。估计的孔半径为1微米的量级。这些孔处于准静止状态，当它们关闭时，它们会在一个快速的过程中自发地关闭（以毫秒计）。对于两种脂质组合物，硬脂酰油酰磷脂酰胆碱和具有50摩尔%胆固醇的硬脂酰油酰磷脂酰胆碱，测定孔区域的线张力，单双层膜的计算值分别为（0.92 ± 0.07）·10−11N和（3.05 ± 0.12）·10−11N。
We present the first observations of giant, long-existing, stabilized pores in vesicle membranes. Using a new experimental technique for studying the electropermeabilization of lipid membranes, giant liposomes (from 25 to 56 μm in diameter) were subjected to single, square, electric pulses (duration 150 μs and electric field strength from 63 to 126 kV/m). The liposomes were held by a micropipet and small membrane tensions were created by controlling the pipet suction pressure. The liposomes were loaded with media having different refractive index from the outside solution, and, under these conditions, the formation of pores in the pressurized liposome could be visualized by the jet of inside solution that flowed out from the membrane pore. By adjusting the membrane tension, pores were kept open, and pore lifetimes could be varied from tenths of a second to several seconds. The pore size was determined from the volumetric flow in the pore region and the measured pressure differences across the bilayer. It was clear from the experiments that only one pore remained opened after the pulse. The estimated pore radii were on the order of one micrometer. The pores were in a quasi-stationary state and when they closed they did so spontaneously in a quick process (in milliseconds). The isotropic membrane tension was determined for the same measurements and from determinations of both pore size and dynamic membrane tension the pore line tension was found. The line tension of the pore region was determined for two lipid compositions, stearoyloleoylphosphatidylcholine and stearoyloleoylphosphatidylcholine with 50 mol% cholesterol, and the obtained values for single bilayers were (0.92 ± 0.07)·10−11N and (3.05 ± 0.12)·10−11N, respectively.