Scattering evidence of positional charge correlations in polyelectrolyte complexes.
Scattering evidence of positional charge correlations in polyelectrolyte complexes.
复制标题
DOI：
10.1073/pnas.2302151120
复制
发表时间：
2023-08-08
影响因子：
11.1
通讯作者：
de Pablo, Juan J.
中科院分区：
文献类型：
--
作者：
Fang, Yan N.;Rumyantsev, Artem M.;Neitzel, Angelika E.;Liang, Heyi;Heller, William T.;Nealey, Paul F.;Tirrell, Matthew V.;de Pablo, Juan J.
关键词：
带相反电荷的聚电解质的化学计量混合物产生宏观聚电解质复合相，可作为细胞内组织某些方面的模型。带相反电荷的静电斑点之间的位置相关性是长期假说的基石，该假说得到了理论的支持，以合理化聚电解质复合物相的内部结构、聚电解质之间的吸引力物理原理以及聚电解质复合物-上清液相平衡。通过小角度中子散射，我们为液体聚电解质复合物中的位置电荷相关性提供了直接的实验证据。实验观察结果与随机相近似和分子动力学模拟的理论预测一致。总的来说，我们的数据证实位置电荷相关性是聚电解质复合结构的一个关键且可观察的特征。聚电解质络合在材料科学和生物学中发挥着重要作用。所得聚电解质复合物 (PEC) 相的内部结构决定了物理状态、对外部刺激的响应和动力学等特性。 X射线和中子的小角散射实验揭示了PEC和中性聚合物半稀溶液之间的结构相似性，其中总散射函数呈现Ornstein-Zernike形式。尽管不同的理论预测达成了共识，但聚阴离子和聚阳离子电荷之间的位置相关性的存在尚未得到实验证实。在这里，我们提出了小角度中子散射剖面，其中聚阳离子散射长度密度与溶剂的散射长度密度相匹配，以提取阴离子单体之间的位置相关性。聚阴离子散射函数在库仑相互作用的逆聚合物屏蔽半径处呈现峰值，q* ≈ 0.2 Å−1。该峰归因于聚阴离子片段之间的库仑排斥及其对聚阳离子的吸引力，在计算的电荷散射函数中更加明显，该函数量化了 PEC 内所有聚合物电荷的位置相关性。通过添加盐来屏蔽静电相互作用导致该相关峰逐渐消失，并且散射函数重新获得奥恩斯坦-泽尼克形式。实验散射结果与随机相位近似、缩放分析和分子模拟计算的结果一致。
Stoichiometric mixtures of oppositely charged polyelectrolytes yield macroscopic polyelectrolyte complex phases that serve as models for certain aspects of intracellular organization. Positional correlations between oppositely charged electrostatic blobs are a cornerstone of a long-standing hypothesis supported by theory to rationalize the internal structure of the polyelectrolyte complex phase, the physics of attractions between polyelectrolytes, and the polyelectrolyte complex–supernatant phase equilibrium. By means of small-angle neutron scattering, we present direct experimental evidence for positional charge correlations in liquid polyelectrolyte complexes. The experimental observations are in line with theoretical predictions from the random phase approximation and molecular dynamics simulations. Collectively, our data confirm positional charge correlations as a crucial and observable feature of the polyelectrolyte complex structure. Polyelectrolyte complexation plays an important role in materials science and biology. The internal structure of the resultant polyelectrolyte complex (PEC) phase dictates properties such as physical state, response to external stimuli, and dynamics. Small-angle scattering experiments with X-rays and neutrons have revealed structural similarities between PECs and semidilute solutions of neutral polymers, where the total scattering function exhibits an Ornstein–Zernike form. In spite of consensus among different theoretical predictions, the existence of positional correlations between polyanion and polycation charges has not been confirmed experimentally. Here, we present small-angle neutron scattering profiles where the polycation scattering length density is matched to that of the solvent to extract positional correlations among anionic monomers. The polyanion scattering functions exhibit a peak at the inverse polymer screening radius of Coulomb interactions, q* ≈ 0.2 Å−1. This peak, attributed to Coulomb repulsions between the fragments of polyanions and their attractions to polycations, is even more pronounced in the calculated charge scattering function that quantifies positional correlations of all polymer charges within the PEC. Screening of electrostatic interactions by adding salt leads to the gradual disappearance of this correlation peak, and the scattering functions regain an Ornstein–Zernike form. Experimental scattering results are consistent with those calculated from the random phase approximation, a scaling analysis, and molecular simulations.
登录
查看更多内容
影响因子：
4.4
作者：
Delaney, Kris T.;Fredrickson, Glenn H.
通讯作者：
Fredrickson, Glenn H.
影响因子：
5.5
作者：
Grzetic, Douglas J.;Delaney, Kris T.;Fredrickson, Glenn H.
通讯作者：
Fredrickson, Glenn H.
影响因子：
6.3
作者：
Brown, W. Michael;Kohlmeyer, Axel;Tharrington, Arnold N.
通讯作者：
Tharrington, Arnold N.
影响因子：
6.1
作者：
Heller, William T.;Cuneo, Matthew;Bras, Wim
通讯作者：
Bras, Wim
影响因子：
5.5
作者：
DAOUD, M;COTTON, JP;GENNES, PGD
通讯作者：
GENNES, PGD