Dynamical mechanism of antifreeze proteins to prevent ice growth
Dynamical mechanism of antifreeze proteins to prevent ice growth
复制标题
DOI：
10.1103/physreve.90.022711
复制
发表时间：
2014-08-13
影响因子：
2.4
通讯作者：
Thoms, S.
中科院分区：
文献类型：
--
作者：
Kutschan, B.;Morawetz, K.;Thoms, S.
藻类、昆虫和鱼类在低于正常冰点的温度下存活的神奇能力是由抗冻蛋白（AFPs）实现的。这些是表面活性分子，与扩散的水-冰界面相互作用，从而防止完全凝固。我们提出了这些蛋白质如何抑制水冻结的动力学机制。我们应用金兹堡-朗道型方法来描述双组分系统（冰，法新社）中的相分离。自由能密度包括两个场：一个是AFP浓度低的冰相场，另一个是AFP浓度高的液态水场。冰的时间演化揭示了在AFPs存在下由于相分离而产生的微观结构。我们观察到，在AFP的作用下，冰前结构的快速聚集与晶粒尺寸的锁定有关，这是一个本质上的动力学过程。额外水分子的吸附被抑制，冰粒的进一步生长停止。冰和水之间的界面能降低，使得原子作用力作用力形成更小的临界冰核。与磁性材料中的磁滞类似，我们观察到热力学磁滞导致凝固点下降的非线性密度依赖，与实验结果一致。
The fascinating ability of algae, insects, and fishes to survive at temperatures below normal freezing is realized by antifreeze proteins (AFPs). These are surface-active molecules and interact with the diffusive water-ice interface thus preventing complete solidification. We propose a dynamical mechanism on how these proteins inhibit the freezing of water. We apply a Ginzburg-Landau-type approach to describe the phase separation in the two-component system (ice, AFP). The free-energy density involves two fields: one for the ice phase with a low AFP concentration and one for liquid water with a high AFP concentration. The time evolution of the ice reveals microstructures resulting from phase separation in the presence of AFPs. We observed a faster clustering of pre-ice structure connected to a locking of grain size by the action of AFP, which is an essentially dynamical process. The adsorption of additional water molecules is inhibited and the further growth of ice grains stopped. The interfacial energy between ice and water is lowered allowing the AFPs to form smaller critical ice nuclei. Similar to a hysteresis in magnetic materials we observe a thermodynamic hysteresis leading to a nonlinear density dependence of the freezing point depression in agreement with the experiments.