Membrane-mediated interactions between circular particles in the strongly curved regime
Membrane-mediated interactions between circular particles in the strongly curved regime
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DOI：
10.1039/c1sm05358b
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发表时间：
2011-01-01
期刊：
影响因子：
3.4
通讯作者：
Deserno, Markus
中科院分区：
文献类型：
--
作者：
Reynwar, Benedict J.;Deserno, Markus
结合到流体脂质膜的颗粒可以引起双层变形，例如当这些颗粒弯曲时。由于两个重叠的曲速场的能量取决于产生它们的两个粒子之间的相互距离，它们将经历由膜的曲率介导的力。如果变形足够弱，则膜形状的相关微分方程是线性的，并且由此产生的相互作用被很好地理解;但是由于问题的高度非线性性质，对于更强的曲率印记知之甚少。在这里，我们数值计算的幅度，这种膜介导的相互作用的情况下，两个轴对称粒子在很宽的曲率印记，深入到非线性制度。我们表明，在一个中间的距离范围内的力的符号反转超过一个足够强的变形。这些发现是定量证实了一个简单的分析近距离扩展。符号翻转可以追溯到两个粒子中间的两个主曲率之间的幅度变化，这只能发生在足够的粒子倾斜时，线性化描述中通过构造排除的条件。我们还表明，这些大的扰动结果同意粗粒度的分子动力学模拟，并建议一个有利的比较确实更有可能在强烈变形的制度。
Particles binding to a fluid lipid membrane can induce bilayer deformations, for instance when these particles are curved. Since the energy of two overlapping warp fields depends on the mutual distance between the two particles creating them, they will experience forces mediated by the curvature of the membrane. If the deformations are sufficiently weak, the associated differential equations for the membrane shape are linear, and the resulting interactions are understood very well; but very little is known for stronger curvature imprint, owing to the highly nonlinear nature of the problem. Here we numerically calculate the magnitude of such membrane-mediated interactions in the case of two axisymmetric particles over a wide range of curvature imprints, deep into the nonlinear regime. We show that over an intermediate distance range the sign of the force reverses beyond a sufficiently strong deformation. These findings are quantitatively confirmed by a simple analytical close-distance expansion. The sign flip can be traced to a change in magnitude between the two principal curvatures midway between the two particles, which can only occur at sufficient particle tilt, a condition which is by construction ruled out in the linearized description. We also show these large perturbation results to agree with coarse-grained molecular dynamics simulations and suggest that a favorable comparison is indeed more likely to hold in the strongly deformed regime.