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

PI: McKenna, Gregory B. / Schroeder, Charles / Anderson， rae提案号：1603943/ 1604038 / 1603925本提案的目标是探索聚合物分子形成大环的行为，而不是通常的线性聚合物分子。这种聚合物，例如DNA分子，在加工过程中或在溶液中流动时的行为方式与线性分子不同，因为链上没有末端。这项工作的结果可能会导致改进聚合物材料，详细了解生物分子的行为，以及DNA测序的新技术。圆形聚合物是一种迷人的材料，几十年来一直激发着聚合物理论家和实验家的灵感。由于没有链端，圆链的动力学与线性链的动力学有根本的不同。然而，尽管最近取得了进展，圆形拓扑结构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。在这个提议中，pi准备通过制备单分散和高拓扑纯度的圆形和线性DNA分子，在我们的理解方面取得重大进展。组建的团队具有合成和表征圆形和线性DNA的专业知识，并将研究这些材料在比以前更大的浓度和分子量范围内的流变行为。提出了一种综合的方法，包括宏观和微观流变学，单分子聚合物动力学和DNA合成，以提供关于线性和圆形DNA动力学的新信息。除了为理解它们的圆形对应体提供一个起点之外，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样本直接测试从重复理论预测，例如在极高纠缠密度下的交叉到重复行为。除了研究生的参与外，所有三个合作机构都提出了教育活动，从德克萨斯理工大学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（主要是本科生机构）的本科生参与。

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 rings, instead of the usual linear polymer molecules. Such polymers, an 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 no 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.