DNA topology dictates emergent bulk elasticity and hindered macromolecular diffusion in DNA-dextran composites
DNA topology dictates emergent bulk elasticity and hindered macromolecular diffusion in DNA-dextran composites
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DOI：
10.1122/8.0000447
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发表时间：
2022-07
影响因子：
3.3
通讯作者：
Pawan Khanal;K. Peddireddy;Juexin Marfai;R. McGorty;R. Robertson-Anderson
中科院分区：
文献类型：
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作者：
Pawan Khanal;K. Peddireddy;Juexin Marfai;R. McGorty;R. Robertson-Anderson
聚合物结构在缠结聚合物溶液和复合材料的本体流变性质以及微观大分子动力学方面都起着关键作用。特别是环形聚合物，由于著名的 reptation模型无法描述其观测到的动力学，一直是众多争论的焦点。宏观流变学和差示动态显微镜（DDM）是确定不同尺度下缠结聚合物动力学的有力方法；然而，它们通常需要在不同条件下的不同样品，这阻碍了本体流变性质与潜在大分子动力学的直接关联。在此，我们对高度重叠的DNA和葡聚糖聚合物的复合材料进行宏观流变学研究，重点关注DNA拓扑结构（环形与线性链）以及DNA和葡聚糖的相对体积分数的作用。在相同条件下的相同样品上，我们在本体测量前后立即对嵌入的荧光标记DNA分子进行DDM和单分子追踪。我们表明DNA - 葡聚糖复合材料在本体粘弹性和分子水平传输性质上对构成复合材料的DNA分数呈现出意想不到的非单调依赖性，其特性强烈依赖于DNA拓扑结构。我们将我们的结果合理地解释为线性DNA的拉伸和聚集，与环形DNA在葡聚糖介导的排空相互作用驱动下的压缩、膨胀和穿线作用相对比而产生的结果。
Polymer architecture plays critical roles in both bulk rheological properties and microscale macromolecular dynamics in entangled polymer solutions and composites. Ring polymers, in particular, have been the topic of much debate due to the inability of the celebrated reptation model to capture their observed dynamics. Macrorheology and differential dynamic microscopy (DDM) are powerful methods to determine entangled polymer dynamics across scales; yet, they typically require different samples under different conditions, preventing direct coupling of bulk rheological properties to the underlying macromolecular dynamics. Here, we perform macrorheology on composites of highly overlapping DNA and dextran polymers, focusing on the role of DNA topology (rings versus linear chains) as well as the relative volume fractions of DNA and dextran. On the same samples under the same conditions, we perform DDM and single-molecule tracking on embedded fluorescent-labeled DNA molecules immediately before and after bulk measurements. We show DNA-dextran composites exhibit unexpected nonmonotonic dependences of bulk viscoelasticity and molecular-level transport properties on the fraction of DNA comprising the composites, with characteristics that are strongly dependent on the DNA topology. We rationalize our results as arising from stretching and bundling of linear DNA versus compaction, swelling, and threading of rings driven by dextran-mediated depletion interactions.