Institute for Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany.
J Phys Chem B. 2012 Aug 16;116(32):9838-45. doi: 10.1021/jp304980e. Epub 2012 Aug 2.
We analyze theoretically the influence of low-dielectric boundaries on the adsorption of flexible polyelectrolytes onto planar and spherical oppositely charged surfaces in electrolyte solutions. We rationalize to what extent polymer chains are depleted from adsorbing interfaces by repulsive image forces. We employ the WKB (Wentzel-Kramers-Brillouin) quantum mechanical method for the Green function of the Edwards equation to determine the adsorption equilibrium. Scaling relations are determined for the critical adsorption strength required to initiate polymer adsorption onto these low-dielectric supports. Image-force repulsion shifts the equilibrium toward the desorbed state, demanding larger surface charge densities and polyelectrolyte linear charge densities for the adsorption to take place. The effect is particularly pronounced for a planar interface in a low-salt regime, where a dramatic change in the scaling behavior for the adsorption-desorption transition is predicted. For the adsorbed state, polymers with higher charge densities are displaced further from the interface by image-charge repulsions. We discuss relevant experimental evidence and argue about possible biological applications of the results.
我们从理论上分析了低介电边界对带电荷聚合物在电解质溶液中于带相反电荷的平面和球形表面上吸附的影响。我们从理论上解释了聚合物链在多大程度上由于排斥的镜像力而从吸附界面被耗尽。我们采用 Wentzel-Kramers-Brillouin (WKB) 量子力学方法对 Edwards 方程的格林函数进行了研究，以确定吸附平衡。确定了引发聚合物吸附到这些低介电支撑体上所需的临界吸附强度的标度关系。镜像力排斥将平衡推向解吸状态，要求更大的表面电荷密度和更高的线性电荷密度才能发生吸附。对于低盐环境中的平面界面，这种效应尤为明显，因为预测到吸附-解吸转变的标度行为会发生剧烈变化。对于吸附状态，由于镜像电荷的排斥，具有更高电荷密度的聚合物会从界面进一步位移。我们讨论了相关的实验证据，并对结果在可能的生物学应用方面进行了论证。
