Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208.
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208;
Proc Natl Acad Sci U S A. 2017 Nov 7;114(45):11838-11843. doi: 10.1073/pnas.1713168114. Epub 2017 Oct 23.
Controlling interactions between proteins and nanoparticles in electrolyte solutions is crucial for advancing biological sciences and biotechnology. The assembly of charged nanoparticles (NPs) and proteins in aqueous solutions can be directed by modifying the salt concentration. High concentrations of monovalent salt can induce the solubilization or crystallization of NPs and proteins. By using a multiscale coarse-grained molecular dynamics approach, we show that, due to ionic correlations in the electrolyte, NPs pairs at high monovalent salt concentrations interact via remarkably strong long-range attractions or repulsions, which can be split into three regimes depending on the surface charge densities of the NPs. NPs with zero-to-low surface charge densities interact via a long-range attraction that is stronger and has a similar range to the depletion attraction induced by polymers with radius of gyrations comparable to the NP diameter. On the other hand, moderately charged NPs with smooth surfaces as well as DNA-functionalized NPs with no possibility of hybridization between them interact via a strong repulsion of range and strength larger than the repulsion predicted by models that neglect ionic correlations, including the Derjaguin-Landau-Vervey-Overbeek (DLVO) model. Interactions between strongly charged NPs (>2 e/nm), both types smooth and DNA-functionalized NPs, show an attractive potential well at intermediate-to-high salt concentrations, which demonstrates that electrolytes can induce aggregation of strongly charged NPs. Our work provides an improved understanding of the role of ionic correlations in NP assembly and design rules to utilize the salting-out process to crystallize NPs.
控制蛋白质和纳米颗粒在电解质溶液中的相互作用对于推进生物科学和生物技术至关重要。通过改变盐浓度，可以指导带电荷的纳米颗粒（NPs）和蛋白质在水溶液中的组装。高浓度的单价盐可以诱导 NPs 和蛋白质的溶解或结晶。通过使用多尺度粗粒分子动力学方法，我们表明，由于电解质中的离子相关性，在高单价盐浓度下，NPs 对通过显著的长程吸引力或排斥力相互作用，这可以根据 NPs 的表面电荷密度分为三个区域。具有零到低表面电荷密度的 NPs 通过长程吸引力相互作用，该吸引力比由与 NP 直径相当的回转半径的聚合物诱导的耗尽吸引力更强，并且范围相似。另一方面，表面光滑的中等带电 NPs 以及彼此之间不可能发生杂交的 DNA 功能化 NPs 通过大于忽略离子相关性的模型（包括 Derjaguin-Landau-Vervey-Overbeek（DLVO）模型）预测的排斥力进行强排斥，该排斥力的范围和强度都较大。在中等至高盐浓度下，强带电 NPs（>2 e/nm）之间的相互作用以及两种类型的光滑和 DNA 功能化 NPs 均表现出吸引力势阱，这表明电解质可以诱导强带电 NPs 的聚集。我们的工作提供了对离子相关性在 NP 组装中的作用以及利用盐析过程来结晶 NPs 的设计规则的更好理解。
