Collaborative Research: Dynamics of Circular Macromolecules (DNA): From Single Molecules to Highly Entangled States

PI：麦肯纳，格雷戈里·B/施罗德，查尔斯/安德森，雷建议编号：1603943/1604038/1603925这项提议的目标是探索形成大环的聚合物分子的行为，而不是通常的线性聚合物分子。这种聚合物，例如DNA分子，在加工时或在溶液中流动时，其行为方式与线性分子不同，因为链上没有末端。这项工作的结果可以带来改进的聚合物材料，详细了解生物分子的行为，以及DNA测序的新技术。环形聚合物是令人着迷的材料，几十年来一直激励着聚合物理论家和实验者。由于没有链端，环链的动力学从根本上不同于它们的线性链。然而，尽管最近取得了进展，但环形拓扑对聚合物动力学的影响仍然是该领域尚未解决的关键问题。在这项提议中，PI准备通过制备单分散和高拓扑纯度的环状和线状DNA分子来在我们的理解上取得重大进展。组建的团队拥有合成和表征环状和线状DNA的专业知识，并将在比以前更广泛的浓度和分子量范围内研究这些材料的流变行为。提出了一种包括宏观和微观流变学、单分子聚合物动力学和DNA合成的综合方法，以提供关于线形和环状DNA动力学的新信息。除了为理解圆形纠缠DNA提供一个出发点之外，对线性纠缠DNA的平行研究将提供前所未有的数据，使用完美的单分散DNA样本来直接测试翻转理论的预测，例如在极高的纠缠密度下的交叉到翻转行为。除了研究生参与，所有三所合作机构都计划开展教育活动，从德克萨斯理工大学代表人数不足的少数族裔学生参与，到伊利诺伊州的高中教师参与，以及圣地亚哥大学的本科生参与。圣地亚哥大学是一所以本科为主的院校。

PI: McKenna, Gregory B. / Schroeder, Charles / Anderson, RaeProposal Number: 1603943/ 1604038 / 1603925 The goal of this proposal is to explore the behavior of polymer molecules that form large ring, instead of the usual linear polymer molecules. Such polymers, example of which can be the DNA molecule, behave in a different way than linear molecules when processed or when they flow in a solution, because there are not ends in the chains. Results of this work can lead to improved polymer materials, to understanding in detail the behavior of bio-molecules and to new technologies for DNA sequencing. Circular polymers are fascinating materials that have inspired polymer theorists and experimentalists for decades. The dynamics of circular chains differ fundamentally from their linear counterparts due to the absence of chain ends. Despite recent progress, however, the effects of circular topology on polymer dynamics remain a key unresolved problem in the field. In this proposal, the PIs are poised to make major progress in our understanding by preparing circular and linear DNA molecules that are monodisperse and of high topological purity. The assembled team has the expertise to synthesize and characterize circular and linear DNA, and will study the rheological behavior of these materials over a wider range of concentrations and molecular weights than previously achieved. A comprehensive approach is proposed that will include macroscopic and micro-rheology, single molecule polymer dynamics, and DNA synthesis, to provide new information regarding the dynamics of linear and circular DNA. Beyond providing a point of departure for understanding their circular counterparts, the parallel study of linear entangled DNA will provide unprecedented data using perfectly monodisperse DNA samples to directly test predictions from reptation theory, such as the cross-over to reptative behavior at extremely high entanglement densities. In addition to graduate student participation, educational activities are proposed in all three collaborating institutions, ranging from underrepresented minority student involvement at Texas Tech, to high school teacher engagement at Illinois and undergraduate student participation at the U of San Diego, a mainly undergraduate institution.