Model for evaluating patterned charge-regulation contributions to electrostatic interactions between low-dielectric spheres.
Model for evaluating patterned charge-regulation contributions to electrostatic interactions between low-dielectric spheres.
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用于评估图案化电荷调节对低介电球之间静电相互作用的贡献的模型。
DOI：
10.1103/physreve.82.031402
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Thurston,GeorgeM
中科院分区：
文献类型：
--
作者：
Hollenbeck,Dawn;Martini,KMichael;Langner,Andreas;Harkin,Anthony;Ross,DavidS;Thurston,GeorgeM
我们研究了静电对两个球形低介电粒子之间的有效电势的贡献，这些粒子在线性化的环境中携带质子可滴定位置。为了评估每种可能的质子占据构型所需的荷电功，以及它对球间距的关键依赖，我们数值求解了一个粗粒线性德拜-胡克尔模型，该模型包含了一系列球间间距下的非均匀介电和离子溶液性质，以及每个球上选定的可滴定电荷位置。我们将得到的电荷功矩阵与质子结合的特定位置化学势结合起来，构建了作为球间分离函数的可滴定位置的每一种可能占据模式的玻尔兹曼加权概率。通过使用这些概率，我们发现非单调平均静电势在较大的球间距时是排斥的，但在近间距时是吸引的。非单调电势对应于特定位置的未占据电荷值及其相应的质子亲和势的特定选择，它的出现与可滴定基团的值有关。对于所选择的可滴定基团，我们确定了从排斥到吸引的质子占据模式随球间间隔的减小而产生建模的非单调依赖的特殊变化，并推导了发生这种非单调依赖的更一般的条件。在本模型中，我们发现，当归一化的Boltzmann平均球间电荷数积等于其协方差与平均电荷自由能除以时，电荷调节的平均静电势的驻点被认为是球间间隔的函数。我们得到了静电球间势中临界点的位置和性质的更一般的条件，这些条件不依赖于本线性模型的有效性。对目前简单的原型模型的分析可以有助于开发一个框架，用于预测(I)图案化的电荷调节占据模式，(Ii)由于相对固定的异质电荷模式而引起的取向相关的吸引力，以及(Iii)筛选的蛋白质净电荷可能分别主导模型生物大分子和其他纳米颗粒之间相互作用的静电部分。
We study the electrostatic contribution to the effective potential between two spherical low-dielectric particles that carry proton-titratable sites within a linearized setting. To evaluate the needed work of charging for each possible proton occupancy configuration, together with its crucial dependence on sphere separation, we numerically solve a coarse-grained linear Debye-Hückel model that incorporates nonuniform dielectric and ionic solution properties at a series of intersphere separations and for chosen titratable charge locations on each sphere. We combine the resulting work-of-charging matrix with site-specific chemical potentials of proton binding to construct the Boltzmann-weighted probabilities of each possible occupancy pattern of the titratable sites as functions of intersphere separation. With the use of these probabilities we find that a nonmonotonic average electrostatic potential can result that is repulsive at larger sphere separations but attractive at close separations. The nonmonotonic potential corresponds to particular choices of site-specific unoccupied charge values and their corresponding proton affinities, and its occurrence is dependent onin relation to thevalues of the titratable groups. For the chosen titratable groups, we identify the particular change from repulsive to attractive proton occupancy patterns with decreasing intersphere separation that gives rise to the modeled nonmonotonic dependence and derive more general conditions under which such a nonmonotonic dependence can occur. Within the present model we find that stationary points of the charge-regulated average electrostatic potential, considered as a function of intersphere separation, occur when a normalized Boltzmann-averaged intersphere charge number product equals its covariance with an average free energy of charging divided by. We derive more general conditions for the location and nature of critical points in the electrostatic intersphere potential, which are not dependent on the validity of the present linear model. Analysis of the present simple prototype model can be a helpful step toward developing a framework for predicting when (i) patterned charge-regulated occupancy patterns, (ii) orientation-dependent attractions due to relatively fixed heterogeneous charging patterns, and (iii) screened net protein charge could separately dominate the electrostatic portion of the interactions between model biological macromolecules and other nanoparticles.
生物学和病理学中的溶酶体
DOI：
--
发表时间：
1969
期刊：
影响因子：
--
作者：
J. Dingle;R. Dean;P. Jacques;I. H. Shaw;W. Sly
通讯作者：
W. Sly