Adsorption Dynamics and Structure of Polycations on Citrate-Coated Gold Nanoparticles
Adsorption Dynamics and Structure of Polycations on Citrate-Coated Gold Nanoparticles
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DOI：
10.1021/acs.jpcc.8b05202
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发表时间：
2018-08-30
影响因子：
3.7
通讯作者：
Hernandez, Rigoberto
中科院分区：
文献类型：
--
作者：
Chong, Gene;Hernandez, Rigoberto
尽管工程多层聚电解质涂覆的金纳米粒子（AuNP）的广泛应用，它们的粒子间相互作用没有完全理解，部分原因是缺乏分子尺度的观察的层-层组装的金纳米粒子涂层。虽然聚电解质涂覆的金纳米颗粒的自上而下的粗粒度模型集中在短长度的聚电解质上，从10到100个单体表示为每个单体一个带电珠，但在这里，我们使用分子动力学和自下而上的粗粒度方法来访问200个单体数量级的更典型的聚合物长度。具体而言，我们模拟的吸附动力学和结构的一个或两个这样长的聚阳离子带负电荷的4纳米柠檬酸盐涂层的金纳米颗粒内隐式或显式溶剂。第一聚阳离子涂覆了大约一半的AuNP表面，而不管溶剂模型如何，并且留下了显著部分的阴离子柠檬酸盐层暴露于第二聚阳离子的吸收。我们发现，在溶剂条件下，最普遍的结构特征包括1-2-单体环或扭结。它们从纳米颗粒表面径向延伸并组装成AuNP的双层涂层。我们编译了一组吸附的聚阳离子的结构特征，这将是成熟的粗粒化，并概述了一个自下而上的粗粒化方案，用于模拟聚电解质涂覆的金纳米粒子与两亲性生物分子，其结合了半球形聚阳离子覆盖与暴露的柠檬酸盐层，表面结合的双层样片段，和长的两亲性环和尾巴。
Despite the widespread application of engineered multilayered polyelectrolyte-coated gold nanoparticles (AuNPs), their interparticle interaction is not fully understood in part because of a lack of molecular scale observation of the layer-by-layer assembly of the polyelectrolyte coating. While top-down coarse-grained models of polyelectrolyte-coated AuNPs have focused on polyelectrolytes of short length, from 10 to a 100 monomers represented as one charged bead per monomer, here we use molecular dynamics and bottom-up coarse-grained approaches to access more typical polymer lengths on the order of 200 monomers. Specifically, we simulate the adsorption dynamics and structure of one or two such long polycations on negatively charged 4 nm citrate-coated AuNPs within implicit or explicit solvents. The first polycation coats approximately half of the AuNP surface regardless of solvent model and leaves a significant part of the anionic citrate layer exposed to absorption by a second polycation. We find that the most prevalent structural features across solvent conditions consist of 1-2-monomer loops or kinks. They extend radially from the nanoparticle surface and assemble into a double-layered coating of the AuNP. We compile a set of structural features of adsorbed polycations that would be ripe for coarse graining and outline a bottom-up coarse-graining scheme for simulations of polyelectrolyte-coated AuNPs with amphiphilic biomolecules that incorporates the hemispheric polycation coverage with exposed citrate layer, surface-bound bilayer-like segments, and long amphiphilic loops and tails.