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Beyond the Poisson-Nernst-Planck Model: The Impacts of Ion Specificity and Electrostatic Correlations on Biological Systems

超越泊松-能斯特-普朗克模型：离子特异性和静电相关性对生物系统的影响

基本信息

批准号：
8957839
负责人：
Hui Zhao
金额：
$ 34.84万
依托单位：
UNIVERSITY OF NEVADA LAS VEGAS
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-09-15 至 2019-08-31
项目状态：
已结题

项目摘要

DESCRIPTION: The classical Poisson-Nernst-Planck (PNP) model of electrolyte solutions has been widely used in biological systems to not only explain experiments but also go beyond to provide a rational design tool for lab- on-a-chip devices. However, many experiments contradict this picture for high salt concentrations, in particular, with multivalent ions, and high surface potentials: there are a significant number of striking qualitative discrepancies between experiments and the PNP model. For example, at high concentrations and high potentials, in the presence of multivalent ions, a reversal of electrophoretic mobility of DNA molecules, the attraction between similarly charged surfaces, flow disappearance, and salt dependence were widely reported in literature. All these observations cannot be captured by the PNP model. Clearly, key physical ingredients are missed in the classical PNP model for the case of high salts and high surface potentials. Consider that in biologically relevant applications, the electrolyte has a high concentration and contains multivalent cations. A new model capturing the missing key physics is necessary to bridge the knowledge gap. Ion specificity and electrostatic correlations are prominent at high salts and high surface potentials. The PNP model assumes that ions are point charges with no volume and interact electrostatically only. The PNP model cannot account for ion specificity and electrostatic correlations. Hence, the specific aims of this application are (1) Go beyond the PNP model and develop a simple local continuum model by integrating ion specificity and electrostatic correlations with non-equilibrium thermodynamic principles; (2) Employ this new model to understand the dynamics of electrolytes at high salt concentrations and high surface potentials, more specifically, advance the fundamental knowledge of electrostatic interactions, and bridge the striking discrepancies between experiments and the existing theoretical model. The developed continuum model will serve as a tool for molecular biophysicists and physiologists to understand, study, and control electrostatic interactions ubiquitously in biology, therefore aiding relevant clinical and technological applications.

描述：经典的Poisson-Nernst-Planck(PNP)电解质溶液模型被广泛应用于生物系统中，不仅用于解释实验，而且还为芯片实验室设备提供了一种合理的设计工具。然而，对于高盐浓度，特别是多价离子和高表面电位，许多实验与这一图景相矛盾：在实验和PNP模型之间有大量显著的定性差异。例如，在高浓度和高电位下，在多价离子存在下，DNA分子的电泳迁移率发生逆转，相似带电表面之间的吸引，流动消失和对盐的依赖在文献中得到了广泛的报道。所有这些观测结果都不能被PNP模型捕捉到。显然，对于高盐和高表面势的情况，经典的PNP模型遗漏了关键的物理成分。考虑到在生物相关的应用中，电解液具有高浓度并且包含多价阳离子。需要一个新的模型来捕捉缺失的关键物理学，以弥合知识鸿沟。离子专一性和静电相关性在高盐度和高表面电位时显著。PNP模型假定离子是无体积的点电荷，只与静电相互作用。PNP模型不能解释离子专一性和静电相关性。因此，这一应用的具体目的是(1)超越PNP模型，通过将离子专一性和静电关联与非平衡热力学原理相结合，建立一个简单的局部连续介质模型；(2)利用这个新模型来理解高盐浓度和高表面电位下的电解液动力学，更具体地说，增进静电相互作用的基础知识，并弥合实验和现有理论模型之间的显著差异。开发的连续介质模型将成为分子生物物理学家和生理学家了解、研究和控制生物学中普遍存在的静电相互作用的工具，从而有助于相关的临床和技术应用。