Computational studies of shape control of charged deformable nanocontainers
Computational studies of shape control of charged deformable nanocontainers
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DOI：
10.1039/c9tb01003c
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发表时间：
2019-11-07
影响因子：
7
通讯作者：
Jadhao, Vikram
中科院分区：
文献类型：
--
作者：
Brunk, Nicholas E.;Jadhao, Vikram
生物物质通常由软膜划分，软膜根据化学和机械提示动态改变其形状。模拟这种行为的可变形软物质纳米膜或纳米容器可以用作药物输送载体，以适应不断变化的生理条件，或者作为通过组装工程设计新型分级材料的动态构建块。在这里，我们使用分子动力学模拟将带电可变形纳米容器的内在特征，如尺寸、电荷、表面张力和弹性与其在广泛的溶液条件下的平衡形状联系起来。这些联系确定了建立化学和材料设计控制策略的基本机制，以调节这些纳米容器的平衡形状。我们发现，半径从10-20 nm的柔性纳米容器表现出从球到棒到盘的形状转变，在很大的长宽比(0.3lt；lambda；lt；5)范围内产生棒和盘。可以通过调节盐和/或表面活性剂的浓度以及材料的弹性参数来控制形状转变。形状的变化是由整体静电能量的降低所驱动的，并与局部表面弹性能分布的剧烈变化有关。为了阐明形状转变机制，对理想的球形纳米容器在无盐条件下进行了精确的解析计算。纳米容器附近的显式反离子模拟和相关的曼宁模型计算提供了在离子凝聚事件中观察到的形状变形的稳定性的评估。
Biological matter is often compartmentalized by soft membranes that dynamically change their shape in response to chemical and mechanical cues. Deformable soft-matter-based nanoscale membranes or nanocontainers that mimic this behavior can be used as drug-delivery carriers that can adapt to evolving physiological conditions, or as dynamic building blocks for the design of novel hierarchical materials via assembly engineering. Here, we connect the intrinsic features of charged deformable nanocontainers such as their size, charge, surface tension, and elasticity with their equilibrium shapes for a wide range of solution conditions using molecular dynamics simulations. These links identify the fundamental mechanisms that establish the chemical and materials design control strategies for modulating the equilibrium shape of these nanocontainers. We show that flexible nanocontainers of radii ranging from 10-20 nm exhibit sphere-to-rod-to-disc shape transitions yielding rods and discs over a wide range of aspect ratio lambda (0.3 < lambda < 5). The shape transitions can be controlled by tuning salt and/or surfactant concentration as well as material elastic parameters. The shape changes are driven by reduction in the global electrostatic energy and are associated with dramatic changes in local surface elastic energy distributions. To illustrate the shape transition mechanisms, exact analytical calculations for idealized spheroidal nanocontainers in salt-free conditions are performed. Explicit counterion simulations near nanocontainers and associated Manning model calculations provide an assessment of the stability of observed shape deformations in the event of ion condensation.