Pretransitional effects in dimyristoylphosphatidylcholine vesicle membranes: Optical dynamometry study
Pretransitional effects in dimyristoylphosphatidylcholine vesicle membranes: Optical dynamometry study
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DOI：
10.1016/s0006-3495(00)76296-5
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发表时间：
2000-07-01
影响因子：
3.4
通讯作者：
Dietrich, C
中科院分区：
文献类型：
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作者：
Dimova, R;Pouligny, B;Dietrich, C
我们使用微米级的乳胶球探测相态和粘弹性的二肉豆蔻酰磷脂酰胆碱（DMPC）双层膜作为温度的函数。一个或两个粒子被操纵并通过光阱粘附到DMPC巨囊泡上。在流体-凝胶主要转变温度以上，Tm等于23.4摄氏度，颗粒可以自发地（布朗运动）或由外力（重力或激光束的辐射压力）驱动在囊泡表面上移动。通过对颗粒运动的分析，我们推导出了膜流体动力学剪切粘度η（s）的值，并发现它在T-m附近会显著增加。低于T-m，粒子的长距离运动被阻挡。我们用两个粘在膜上的粒子进行了实验。通过光学测力法，我们测量了膜的弹性阻力的变化，在粒子间的距离，并发现它会大大减少（下降到零），当温度升高到T-m。我们提出了一个解释有关的弹性响应的膜曲率模量，k（C）。在该方案中，双珠测力实验提供了脂质双层的P-β '相中的k（C）的直接测量。
We used micron-sized latex spheres to probe the phase state and the viscoelastic properties of dimyristoylphosphatidylcholine (DMPC) bilayers as a function of temperature. One or two particles were manipulated and stuck to a DMPC giant vesicle by means of an optical trap. Above the fluid-gel main transition temperature, T-m congruent to 23.4 degrees C, the particles could move on the surface of the vesicle, spontaneously (Brownian motion) or driven by an external force, either gravity or the laser beam's radiation pressure. From the analysis of the particle motions, we deduced the values of the membrane hydrodynamic shear viscosity, eta(s), and found that it would increase considerably near T-m. Below T-m, the long-distance motion of the particles was blocked. We performed experiments with two particles stuck on the membrane. By optical dynamometry, we measured the elastic resistance of the membrane to a variation in the interparticle distance and found that it would decrease considerably (down to zero) when the temperature was increased to T-m. We propose an interpretation relating the elastic response to the membrane curvature modulus, k(C). in this scheme, the two-bead dynamometry experiments provide a direct measurement of k(C) in the P-beta' phase of lipid bilayers.