Topology-Controlled Relaxation Dynamics of Single Branched Polymers
Topology-Controlled Relaxation Dynamics of Single Branched Polymers
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DOI：
10.1021/acsmacrolett.5b00140
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发表时间：
2015-04-01
影响因子：
7.015
通讯作者：
Schroeder, Charles M.
中科院分区：
文献类型：
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作者：
Mai, Danielle J.;Marciel, Amanda B.;Schroeder, Charles M.
在这项工作中，我们报告的合成和直接观察的分支DNA聚合物使用单分子技术。聚合物拓扑结构在决定先进材料的性能方面起着重要作用，但理解这些复杂大分子的动力学一直具有挑战性。在这里，我们研究了单表面束缚梳形聚合物在微流体装置中从高拉伸的构象弛豫动力学。我们的研究结果表明，单个支化聚合物的分子拓扑结构对具有复杂结构的聚合物的弛豫动力学起着直接的作用。首先使用混合酶促合成方法合成大分子DNA梳，其中在单独的聚合酶链式反应中产生化学修饰的DNA分支和DNA主链，然后通过应变促进的[3 + 2]叠氮化物-炔环加成进行“接枝”反应。该方法允许合成具有几乎单分散主链和分支分子量的支化聚合物。然后使用单分子荧光显微镜直接可视化支化聚合物，使得可以使用单色或双色荧光标记独立地跟踪主链和侧支。使用这种方法，我们表征支化聚合物的分子性质，包括表观轮廓长度和分支接枝分布。最后，我们研究了单梳形聚合物在流体流动停止后的高拉伸松弛动力学，发现聚合物的松弛依赖于分支接枝密度和分支点沿着主链的位置。总的来说，这项工作有效地扩展了单聚合物动力学的分支聚合物，这使得动态，分子尺度的观察聚合物与复杂的拓扑结构。
In this work, we report the synthesis and direct observation of branched DNA polymers using single molecule techniques. Polymer topology plays a major role in determining the properties of advanced materials, yet understanding the dynamics of these complex macromolecules has been challenging. Here, we study the conformational relaxation dynamics of single surface-tethered comb polymers from high stretch in a microfluidic device. Our results show that the molecular topology of individual branched polymers plays a direct role on the relaxation dynamics of polymers with complex architectures. Macromolecular DNA combs are first synthesized using a hybrid enzymatic-synthetic approach, wherein chemically modified DNA branches and DNA backbones are generated in separate polymerase chain reactions, followed by a "graft-onto" reaction via strain-promoted [3 + 2] azide-alkyne cycloaddition. This method allows for the synthesis of branched polymers with nearly monodisperse backbone and branch molecular weights. Single molecule fluorescence microscopy is then used to directly visualize branched polymers, such that the backbone and side branches can be tracked independently using single- or dual-color fluorescence labeling. Using this approach, we characterize the molecular properties of branched polymers, including apparent contour length and branch grafting distributions. Finally, we study the relaxation dynamics of single comb polymers from high stretch following the cessation of fluid flow, and we find that polymer relaxation depends on branch grafting density and position of branch point along the main chain backbone. Overall, this work effectively extends single polymer dynamics to branched polymers, which allows for dynamic, molecular-scale observation of polymers with complex topologies.