Effect of the Electrostatic Interactions on Lubrication in Biological and Polymeric Systems

该奖项支持生物材料及其在哺乳动物关节润滑中的作用的理论和计算研究和教育。摩擦和润滑在日常生活中扮演着重要的角色。许多生物表面，如软骨、肺中的气道表层、眼睛中的粘蛋白层，都覆盖有由糖蛋白组成的刷状粘附层。这些刷层具有非常低的摩擦系数在0.001-0.03的范围内，可以承受的压力的顺序为ten atmospheres.The PI将使用的分子动力学模拟，自洽场计算和缩放分析的组合，以开发一个糖蛋白层的润滑模型。 这种方法是基于糖蛋白的粗粒度模型，其中它被表示为一个强电荷的分子bottlebrush组成的侧链接枝到主链骨架。研究将集中在两个瓶刷层之间的相互作用。理论和模拟将被用来计算刷层厚度，层的可压缩性，和链松弛动力学的盐浓度，溶液pH值，带电基团的分数，分子结构，和滑动速度的函数。分子动力学模拟将进行明确的溶剂，以阐明在滑动阻尼层的能量耗散的流体动力学耦合的效果。该模型将被应用于描述多层涂层的润滑。将模拟和理论结果与合成瓶刷层之间和两个多层涂层之间的摩擦系数的实验数据进行比较。这项研究可能有助于发现新的途径，开发具有优异的润滑性能的生物医学应用的聚合物涂层。 本研究项目将培养研究生掌握现代分析和计算技术。高中学生也将通过康州大学导师连接计划接触到研究。 这将拓宽学生的智力，并为每个人提供对未来问题和技术的独特见解。学生的辅导被纳入拟议研究的各个方面。 研究生将与本科物理，化学或化学工程专业的学生和有才华的高中生一起工作。这些经验将为他们未来的学术生涯做好准备。教育和科学研究中代表性不足的群体将通过荣誉计划和REU网站的现有基础设施参与。拟议研究的结果将被纳入“高分子物理”课程序列，和“高分子物理化学”以及新的专题课程“含离子聚合物”该奖项支持生物材料及其在生物系统中润滑作用的理论和计算研究和教育。摩擦和润滑是我们日常生活的一部分，从机械到生物有机体。许多结缔组织，如软骨，表现出优异的润滑和磨损特性。哺乳动物关节中的腕骨可以承受十倍于大气压的压力，并且在移动时摩擦力非常小。软骨表面覆盖着一层刷状的大分子，这些分子带有电荷。该刷层，其面对相对软骨上的类似层，在关节运动期间当两个表面滑动通过彼此时被剪切。PI将使用计算机模拟和理论方法来理解刷层之间的复杂相互作用，以及它如何导致生物和链状分子系统的润滑性能。这些知识将能够解释软骨滑动表面之间的低摩擦。这项研究将有助于进一步了解其他生物表面的润滑特性，例如肺中的气道表面层和胃肠道中的粘蛋白层，其中刷状分子形成保护界面层。这项研究项目将培养现代分析和计算技术的研究生。高中学生也将通过康州大学导师连接计划接触到研究。 这将拓宽学生的智力，并为每个人提供对未来问题和技术的独特见解。学生的辅导被纳入拟议研究的各个方面。 研究生将与本科物理，化学或化学工程专业的学生和有才华的高中生一起工作。这些经验将为他们未来的学术生涯做好准备。教育和科学研究中代表性不足的群体将通过荣誉计划和REU网站的现有基础设施参与。高分子物理学？然后呢？高分子物理化学以及新的专题课程？含离子聚合物？

TECHNICAL SUMMARYThis award supports theoretical and computational research and education in biomaterials and their role in mammalian joint lubrication. Friction and lubrication play an important role in everyday experience. Many biological surfaces such as such as cartilage, airway surface layers in the lungs, mucin layers in the eyes, are covered with a brush-like polyelectrolyte layer consisting of glycoproteins. These brush layers have remarkably low friction coefficient in the range 0.001-0.03 and can withstand pressures of the order of ten atmospheres.The PI will use a combination of the molecular dynamics simulations, self-consistent field calculations, and scaling analysis to develop a model of lubrication of glycoprotein layers. This approach is based on a coarse-grained model of glycoprotein in which it is represented as a strongly charged molecular bottlebrush consisting of side chains grafted to the main chain backbone. The research will focus on the interaction between two bottlebrush layers. Theory and simulation will be used to calculate the brush layer thickness, the layer compressibility, and the chain relaxation dynamics as a function of salt concentration, solution pH, fraction of charged groups, the molecular architecture, and the sliding velocity. Molecular dynamics simulations will be performed with explicit solvent to elucidate the effect of the hydrodynamic coupling on the energy dissipation in sliding polyelectrolyte layers. The developed model will be applied to describe lubrication in multilayered polyelectrolyte coatings. The simulation and theoretical results will be compared with experimental data for friction coefficient between synthetic bottlebrush layers and between two multilayer coatings. This study may help to discover new routes for developing polymeric coatings with excellent lubricating properties for biomedical applications. This research project will train graduate students in modern analytical and computational techniques. High school students will also be exposed to the research through the UConn Mentor Connection Program. This will broaden students intellectually and provide each with a unique insight into the problems and technology of the future. Mentoring of students is integrated into every aspect of the proposed research. Graduate students will work with undergraduate physics, chemistry or chemical engineering students and with talented high school students. This experience will prepare them for future academic careers. Underrepresented groups in education and scientific research will be involved through the Honors Program and existing infrastructure of the REU sites.The results of the proposed research will be incorporated into the course sequences on "Polymer Physics", and "Polymer Physical Chemistry" as well as into a new special topics course "Ion-containing polymers".NONTECHNICAL SUMMARYThis award supports theoretical and computational research and education in biomaterials and their role in lubrication in biological systems. Friction and lubrication are a part of our everyday experience ranging from machinery to biological organisms. Many connective tissues, such as cartilage, demonstrate excellent lubrication and wear characteristics. Cartilage in the joints of mammals can withstand pressures ten times atmospheric pressure and move with remarkably little friction. The surface of the cartilage is covered with a brush-like layer of large chain-like molecules that have electrical charges. This brush layer, which faces a similar layer on the opposing cartilage, is sheared as two surfaces slide passing each other during joint motion. The PI will use computer simulations and theoretical methods to understand the complex interaction between brush layers and how it leads to the lubricating properties of biological and chain-like molecular systems. This knowledge will enable the explanation of the low friction between sliding surfaces of the cartilage. This research will help advance understanding of lubrication properties of other biological surfaces, such as airways surface layer in lungs and the mucin layer in gastrointestinal tract, where brush-like molecules form protective interfacial layers.This research project will train graduate students in modern analytical and computational techniques. High school students will also be exposed to the research through the UConn Mentor Connection Program. This will broaden students intellectually and provide each with a unique insight into the problems and technology of the future. Mentoring of students is integrated into every aspect of the proposed research. Graduate students will work with undergraduate physics, chemistry or chemical engineering students and with talented high school students. This experience will prepare them for future academic careers. Underrepresented groups in education and scientific research will be involved through the Honors Program and existing infrastructure of the REU sites.The results of the proposed research will be incorporated into the course sequences on ?Polymer Physics?, and ?Polymer Physical Chemistry? as well as into a new special topics course ?Ion-containing polymers?.