Molecular dynamics simulation studies of the transport and adsorption of a charged macromolecule onto a charged adsorbent solid surface immersed in an electrolytic solution.
Molecular dynamics simulation studies of the transport and adsorption of a charged macromolecule onto a charged adsorbent solid surface immersed in an electrolytic solution.
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DOI：
10.1016/j.jcis.2004.04.048
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发表时间：
2004-09
影响因子：
9.9
通讯作者：
Xiaomin Zhang;Jee-Ching Wang;Karol M. Lacki;A. Liapis
中科院分区：
文献类型：
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作者：
Xiaomin Zhang;Jee-Ching Wang;Karol M. Lacki;A. Liapis
采用分子动力学模拟方法研究了电解质溶液中带电荷的大分子（去氨加压素）在带电荷固体表面上的迁移和吸附。来自带电固体表面的强库仑相互作用代表了加速、定向、捕获在双电层中以及将大分子吸附到带电固体表面上的主要力。当大分子接近带电表面时，它被压平，产生更强的表面排斥效应，屏蔽表面位点。当吸附时，大分子受到比热能强100倍以上的表面相互作用的限制，其中99.8%来自强主导库仑相互作用，并被邻近表面的水合层捕获。这导致吸附的大分子的零横向位移，并表明表面扩散是一个物理上难以置信的机制，在类似的系统。明确的溶剂是需要现实的大分子结构和表面相互作用能的代表性。吸附的大分子还降低了垂直于带电固体表面的静电势梯度，并在横向上引入了额外的静电势梯度。从分子动力学模拟得到的结果证实了电泳迁移的重要性，并支持在宏观连续模型中使用的物理机制，该模型预测在一定条件下的pH值和离子强度的吸附相的带电大分子的浓度的过冲。
Molecular dynamics simulations were performed in order to study the transport and adsorption of a charged macromolecule (desmopressin) onto a charged solid surface in an electrolytic solution. The strong Coulombic interaction from the charged solid surface represents the major force for accelerating, orienting, entrapping in the electrical double layer, and adsorbing the macromolecule onto the charged solid surface. The macromolecule is flattened as it approaches the charged surface, giving rise to a stronger surface exclusion effect that shields surface sites. When adsorbed, the macromolecule is restrained by a surface interaction more than one hundred times stronger than the thermal energy, of which 99.8% results from the strong dominant Coulombic interaction, and trapped by a hydration layer adjacent to the surface. This leads to zero lateral displacement of the adsorbed macromolecule and indicates that surface diffusion is a physically implausible mechanism in similar systems. Explicit solvent is required for realistic representation of the macromolecular structure and the surface interaction energy. The adsorbed macromolecule also decreased the electrostatic potential gradient perpendicular to the charged solid surface and introduced additional electrostatic potential gradients laterally. The results obtained from the molecular dynamics simulations confirm the importance of electrophoretic migration and support the physical mechanisms used in a macroscopic continuum model that predicts an overshoot in the concentration of a charged macromolecule in the adsorbed phase under certain conditions of pH and ionic strength.