The origin of long-range attraction between hydrophobes in water
The origin of long-range attraction between hydrophobes in water
复制标题
DOI：
10.1529/biophysj.106.087023
复制
发表时间：
2007-01-01
影响因子：
3.4
通讯作者：
Berry, R. Stephen
中科院分区：
文献类型：
--
作者：
Despa, Florin;Berry, R. Stephen
当水涂覆的疏水表面相遇时，表面之间形成直接接触，将水排出。然而，长程引力首先使这些表面靠近。该分析揭示了水涂覆的疏水表面之间的长程吸引力的来源和强度。起源是在极化场所产生的强关联和耦合的偶极子的水分子在表面。我们表明，这种极化场引起的偶极子表面上的疏水溶质，产生远程疏水吸引力。因此，疏水聚集开始于水包被的非极性溶质由于长程静电力而彼此接近的步骤。这种前体状态发生在释放水层的熵增加之前，并且短程货车德瓦尔斯吸引力提供了使接触表面“变干”的驱动力。有效吸引力是从基本的分子原理推导出来的，没有假设疏水-水相互作用的结构。这种力的强度可以直接从原子力显微镜图像中测量，其中一个疏水分子被拴在表面上，但延伸到水中，另一个疏水分子连接到原子力探针上。在水质子磁共振的横向弛豫率中也可以观察到这种现象。结果揭示了水介导化学和生物自组装的方式，这是一个长期悬而未决的问题。
When water-coated hydrophobic surfaces meet, direct contacts form between the surfaces, driving water out. However, long-range attractive forces first bring those surfaces close. This analysis reveals the source and strength of the long-range attraction between water-coated hydrophobic surfaces. The origin is in the polarization field produced by the strong correlation and coupling of the dipoles of the water molecules at the surfaces. We show that this polarization field gives rise to dipoles on the surface of the hydrophobic solutes that generate long-range hydrophobic attractions. Thus, hydrophobic aggregation begins with a step in which water-coated nonpolar solutes approach one another due to long-range electrostatic forces. This precursor regime occurs before the entropy increase of releasing the water layers and the short-range van der Waals attraction provide the driving force to "dry out'' the contact surface. The effective force of attraction is derived from basic molecular principles, without assumptions of the structure of the hydrophobe-water interaction. The strength of this force can be measured directly from atomic force microscopy images of a hydrophobic molecule tethered to a surface but extending into water, and another hydrophobe attached to an atomic force probe. The phenomenon can be observed in the transverse relaxation rates in water proton magnetic resonance as well. The results shed light on the way water mediates chemical and biological self-assembly, a long outstanding problem.