Anomalous Self-Diffusion and Sticky Rouse Dynamics in Associative Protein Hydrogels,Journal of the American Chemical Society

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Anomalous Self-Diffusion and Sticky Rouse Dynamics in Associative Protein Hydrogels
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2015-03-12 , DOI: 10.1021/jacs.5b00722
Shengchang Tang ₁ , Muzhou Wang ₁ , Bradley D. Olsen ₁

Affiliation

Natural and synthetic materials based on associating polymers possess diverse mechanical behavior, transport properties and responsiveness to external stimuli. Although much is known about their dynamics on the molecular and macroscopic level, knowledge of self-diffusive dynamics of the network-forming constituents remains limited. Using forced Rayleigh scattering, anomalous self-diffusion is observed in model associating protein hydrogels originating from the interconversion between species that diffuse in both the molecular and associated state. The diffusion can be quantitatively modeled using a two-state model for polymers in the gel, where diffusivity in the associated state is critical to the super diffusive behavior. The dissociation time from bulk rheology measurements was 2-3 orders of magnitude smaller than the one measured by diffusion, because the former characterizes submolecular dissociation dynamics, whereas the latter depicts single protein molecules completely disengaging from the network. Rheological data also show a sticky Rouse-like relaxation at long times due to collective relaxation of large groups of proteins, suggesting mobility of associated molecules. This study experimentally demonstrates a hierarchy of relaxation processes in associating polymer networks, and it is anticipated that the results can be generalized to other associative systems to better understand the relationship of dynamics among sticky bonds, single molecules, and the entire network.

中文翻译：

缔合蛋白水凝胶中的异常自扩散和粘滞动力学

基于缔合聚合物的天然和合成材料具有不同的机械行为、传输特性和对外部刺激的响应能力。尽管在分子和宏观层面上对它们的动力学了解很多，但对网络形成成分的自扩散动力学的了解仍然有限。使用强制瑞利散射，在模型关联蛋白质水凝胶中观察到异常自扩散，该模型源自以分子状态和相关状态扩散的物种之间的相互转化。可以使用凝胶中聚合物的双态模型对扩散进行定量建模，其中相关态的扩散率对超扩散行为至关重要。体积流变测量的解离时间比扩散测量的解离时间小 2-3 个数量级，因为前者表征亚分子解离动力学，而后者描绘了完全脱离网络的单个蛋白质分子。由于大量蛋白质的集体松弛，流变学数据还显示了长时间的粘性 Rouse 样松弛，这表明相关分子的流动性。这项研究通过实验证明了关联聚合物网络中的弛豫过程层次结构，预计结果可以推广到其他关联系统，以更好地理解粘键、单分子和整个网络之间的动力学关系。由于大量蛋白质的集体松弛，流变学数据还显示了长时间的粘性 Rouse 样松弛，这表明相关分子的流动性。这项研究通过实验证明了关联聚合物网络的松弛过程层次结构，预计结果可以推广到其他关联系统，以更好地理解粘键、单分子和整个网络之间的动力学关系。由于大量蛋白质的集体松弛，流变学数据还显示了长时间的粘性 Rouse 样松弛，这表明相关分子的流动性。这项研究通过实验证明了关联聚合物网络中的弛豫过程层次结构，预计结果可以推广到其他关联系统，以更好地理解粘键、单分子和整个网络之间的动力学关系。

更新日期：2015-03-12

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