Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
Langmuir. 2012 Feb 28;28(8):3881-6. doi: 10.1021/la204060k. Epub 2012 Feb 13.
Interactions between ions and solutes are key to ion-specificity. A generic model in which ions interact via square well potentials of finite range with charged plates is solved analytically on the Poisson-Boltzmann level and analyzed globally for varying surface charge, salt concentration, and ion-surface affinity. Ion adsorption as well as depletion can lead to stably bound plates at finite separation, relevant for the equilibrium salting-out of small solutes such as proteins. The interplate pressure at large plate separation, relevant for aggregation kinetics of large solutes, exhibits direct as well as indirect Hofmeister ordering, depending on surface charge and salt concentration. A simple method for mapping explicit ion-surface potentials of mean force as obtained from solvent-explicit molecular dynamics simulations onto square-well potential parameters is demonstrated.
离子与溶质之间的相互作用是离子特异性的关键。在一个通用模型中，离子通过有限范围的方阱势与带电板相互作用，该模型在泊松-玻尔兹曼水平上进行了分析，并针对不同的表面电荷、盐浓度和离子-表面亲和力进行了全局分析。离子吸附和耗尽都会导致在有限的分离下稳定结合的板，这对于小分子（如蛋白质）的平衡盐析是很重要的。在大的板分离下，与大溶质的聚集动力学相关的板间压力，表现出直接和间接的霍夫迈斯特排序，这取决于表面电荷和盐浓度。本文演示了一种将从溶剂显式分子动力学模拟中获得的平均力面离子势映射到方阱势参数的简单方法。
