On the mechanism of uptake of globular proteins by polyelectrolyte brushes: A two-gradient self-consistent field analysis
On the mechanism of uptake of globular proteins by polyelectrolyte brushes: A two-gradient self-consistent field analysis
复制标题
DOI：
10.1021/la0632777
复制
发表时间：
2007-03-27
期刊：
影响因子：
3.9
通讯作者：
Borisov, O. V.
中科院分区：
文献类型：
--
作者：
Leermakers, F. A. M.;Ballauff, M.;Borisov, O. V.
我们提出了类蛋白质不均匀带电纳米级物体与一层致密接枝聚电解质（“聚电解质刷”）相互作用的模型计算。这项工作的动机是最近的实验观察到，整体带有负电荷的蛋白质被吸收到带负电的聚电解质刷中。已经进行了二梯度自洽场（2G-SCF）计算，以揭示由此影响的蛋白质吸收的物理机制。我们的结果证明，当物体有两个面（斑块、域）时，整体中性的类蛋白质物体可以被静电吸引，因此自发地驱动到聚电解质刷中，一个面带有永久正电荷，另一个面带有永久负电荷。使用 2G-SCF 分析，我们评估插入的自由能，使得夹杂物的电偶极子平行于刷表面。电中性的类蛋白质物体被吸引到刷子中，因为聚电解质刷与相反符号的带电斑块不对称地相互作用。在斑块上的高离子强度和低电荷密度下，吸引力无法与排斥体积相互作用竞争。然而，对于低离子强度和斑块上足够高的电荷密度，每次电荷获得 k(B)T 数量级的增益成为可能。因此，不同电荷斑块相互作用的不对称性可能导致蛋白质和刷子之间的总吸引力。本文获得的所有结果与最近的实验数据非常一致。
We present model calculations for the interaction of a protein-like inhomogeneously charged nanoscale object with a layer of densely grafted polyelectrolytes ("polyelectrolyte brush"). The motivation of this work is the recent experimental observation that proteins that carry an overall negative charge are absorbed into negatively charged polyelectrolyte brushes. Two-gradient self-consistent field (2G-SCF) calculations have been performed to unravel the physical mechanism of the uptake of protein thus effected. Our results prove that an overall neutral, protein-like object can electrostatically be attracted and therefore spontaneously driven into a polyelectrolyte brush when the object has two faces (patches, domains), one with a permanent positive charge and the other with a permanent negative charge. Using a 2G-SCF analysis, we evaluate the free energy of insertion, such that the electric dipole of the inclusion is oriented parallel to the brush surface. An electroneutral protein-like object is attracted into the brush because the polyelectrolyte brush interacts asymmetrically with the charged patches of opposite sign. At high ionic strength and low charge density on the patches, the attraction cannot compete with the repulsive excluded-volume interaction. However, for low ionic strengths and sufficiently high charge density on the patches, a gain on the order of k(B)T per charge becomes possible. Hence, the asymmetry of interaction for patches of different charges may result in a total attractive force between the protein and the brush. All results obtained herein are in excellent agreement with recent experimental data.