The Howard P. Isermann Department of Chemical & Biological Engineering and the Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
Langmuir. 2009 Nov 17;25(22):13092-9. doi: 10.1021/la9011839.
We present an extensive molecular simulation study of the behavior of a flexible hydrophobic 25-mer polymer at interfaces presenting a range of chemistries from hydrophobic (-CH(3)) to hydrophilic (-CONH(2)). We quantify the free energy of adsorption, conformational equilibria, and translational and conformational dynamics of the polymer at these diverse interfaces. Water-mediated interactions drive the polymer to adsorb strongly at a hydrophobic interface and repel it from hydrophilic ones. At hydrophilic surfaces, van der Waals interactions between the polymer and the surface mitigate this water-mediated repulsion, leading to weak adsorption of the polymer. Although the polymer is strongly adsorbed to hydrophobic surfaces, it is also most dynamic there. Translational diffusion and conformational dynamics are faster at hydrophobic surfaces compared to those at hydrophilic ones. In bulk water, the polymer collapses into compact globular shapes, whereas the thermodynamic stability of folded polymers is significantly lowered at hydrophobic surfaces. The polymer spreads into pancake-like 2D conformations at hydrophobic surfaces and gradually beads up into globular shapes as the surface is made more hydrophilic. Interestingly, the binding thermodynamics and dynamics correlate with macroscopic droplet contact angles that characterize the wetting properties of the different interfaces.
我们进行了广泛的分子模拟研究，以了解从疏水（-CH(3)）到亲水（-CONH(2)）的各种化学性质的界面上，柔性疏水 25 聚体聚合物的行为。我们定量了聚合物在这些不同界面上的吸附自由能、构象平衡以及平移和构象动力学。水介导的相互作用促使聚合物在疏水界面上强烈吸附，并排斥其在亲水界面上的吸附。在亲水表面，聚合物与表面之间的范德华相互作用减轻了这种水介导的排斥作用，导致聚合物的弱吸附。尽管聚合物在疏水表面强烈吸附，但在该表面上聚合物也最具动态性。与亲水表面相比，聚合物在疏水表面上的平移扩散和构象动力学更快。在本体水中，聚合物会塌陷成紧凑的球状形状，而在疏水表面上，折叠聚合物的热力学稳定性显著降低。聚合物在疏水表面上展开成类似煎饼的 2D 构象，并随着表面变得更加亲水而逐渐珠状化。有趣的是，结合热力学和动力学与宏观液滴接触角相关，液滴接触角可以表征不同界面的润湿性质。
