Collaborative Research: Biomimetic Lubricants: Gels based on Biomolecules and Nanoparticles with Ultralow Coefficients of Friction

从机械中的运动部件到关节的生物润滑，润滑剂在几项技术的运行和生物学中发挥着不可或缺的作用。润滑剂的主要用途是减少摩擦和表面磨损。我们提出了一个合作项目，其中包括杜兰大学的3名教员和马里兰大学的1名教员，每个人都拥有项目成功所需的独特专业知识。派(N·佩西卡)是一名二年级的初级教员，曾是加州大学洛杉矶分校接口实验室的博士后助理，在伊斯拉克维利博士的指导下工作。近年来，N·佩西卡为了解壁虎的粘着机理进行了理论和实验工作，并精通摩擦学和润滑剂的表征。约翰是一名高级教员，在表面和胶体科学领域拥有丰富的经验，特别是在胶体的合成和改性方面。阿什博的研究侧重于分子的多尺度模拟和自组装过程的理论，包括表面活性剂、聚合物熔体和生物聚合物凝胶。S.Raghavan是马里兰大学复杂流体和纳米材料小组的负责人，也是自组装软材料方面的权威。我们发现，容易合成的单分散硬碳亚微米球形颗粒(HCS)体系的摩擦系数开始接近滑膜流体的摩擦系数。当这些观察结果与S.Raghavan实验室的一项新发现相结合时，即一种经修饰的生物聚合物(壳聚糖)能够凝胶化小泡，我们能够实现一种独特的凝胶系统，该体系包含作为该生物聚合物网络节点的碳微球。这构成了我们提出的开发包含单分散颗粒或缓冲小泡的新型凝胶润滑剂的基础。我们的假设是，通过生物分子/生物聚合物的边界润滑和HCS颗粒所采用的滚动机制(类似于滚珠轴承)，这些复合材料将能够协同减少摩擦和最大限度地减少表面磨损。因此，我们建议开发具有超低摩擦系数的仿生润滑剂，这种润滑剂坚固耐用，易于合成。由磷脂基脂质体、生物聚合物和碳微球组成的几种配方将通过分子和颗粒设计来优化润滑性，包括低摩擦系数和最小的表面磨损。研究的广泛影响：虽然已经研制出几种类型的润滑剂，但模拟滑液的水基润滑剂仍然难以捉摸。一种具有超低摩擦系数的仿生润滑剂具有多种应用，包括在疾病或损伤的关节中作为滑液的潜在替代品，或在微流体或微型机电设备中的应用。潜在的科学影响非常广泛，影响到所有使用润滑油的行业。广泛的教育和推广努力：N.Pesika和H.Ashbaugh致力于改善当地的K-12教育，并在新奥尔良特许科学和数学(NOCSM)高中设立了服务学习课程。学校的人口结构与社区的人口结构非常相似，85%的学生来自被归类为经济困难的家庭，86%的学生人口属于少数群体(82%的非裔美国人)。该推广计划旨在通过杜兰大学学生的演讲展示科学方法的日常使用，并通过实验阐明所演示现象的性质，如生物聚合物的流变性和热机的操作。在过去的8年里，V.John一直是LAMP(路易斯安那州少数民族参与研究联盟)计划的始终如一的参与者，每年夏天都会监督一到两名学生，而N.Pesika将在夏天开始参与LAMP计划。这些少数族裔学生通常来自该州的少数族裔机构(泽维尔、南部、格拉姆布林州立大学)或来自包括杜兰在内的非少数族裔新奥尔良机构。我们计划申请REU补充剂，这将通过LAMP计划加以利用。

Lubricants play an integral role in the operation of several technologies and in biology, ranging from moving parts in machinery to the biolubrication of articular joints. The main purposes of a lubricant are to reduce friction and surface wear. We propose a collaborative project involving 3 faculty members fromTulane University and a faculty member from the University of Maryland, each bearing unique expertise required for the success of the project. The PI (N. Pesika) is a junior faculty in his 2nd year and was a postdoctoral associate in the Interface laboratory at UCSB working under the guidance of Dr. Israelachvili. In recent years, N. Pesika has done theoretical and experimental work to understand the adhesion mechanism of the gecko and has become proficient in tribology and the characterization of lubricants. V. John is a senior faculty member with experience in the field of surface and colloidal science, specifically in the synthesis and modification of colloids. H. Ashbaugh's research focuses on the multiscale simulation and the theory of self assembly processes of molecules including surfactants, polymer melts, and biopolymer gels. S. Raghavan heads the complex fluid and nanomaterials group at the University of Maryland, and is an authority on self-assembling soft materials. We have found that an easily synthesized system of monodisperse hard carbon submicron spherical particles (HCS) has frictional coefficients that start approaching those of synovial fluids. When these observations are coupled with a novel discovery in S. Raghavan's laboratory that a modified biopolymer (chitosan) is able to gel vesicles, we are able to realize a unique gel system containing the carbon microspheres serving as nodes in a network of this biopolymer. This forms the basis of our proposed work to develop novel gel based lubricants containing monodisperse particles or cushioning vesicles. Our hypothesis is that these composite materials will be able to reduce friction and minimize surface wear synergistically through the boundary lubrication of biomolecules/biopolymers and the rolling mechanism (similar to ball bearings) employed by HCS particles. We therefore propose to develop biomimetic lubricants with ultralow coefficients of friction that are robust and easy to synthesize. Several formulations composed of phospholipid based liposomes, biopolymers and carbon microspheres will be systematically explored to optimize the lubrication properties, including a low coefficient of friction and minimal surface wear, through molecular and particulate design.Broader Impacts of research: While several types of lubricants have been formulated water-based lubricants that mimic synovial fluid remain elusive. A biomimetic lubricant exhibiting ultralow coefficient of friction has several applications including potential substitutes for synovial fluid in diseased or damaged articular joints or in applications to microfluidics or microelectromechanical devices. The potential scientific impact is extremely broad, affecting all industries utilizing lubricants.Broader Educational and Outreach efforts: N. Pesika and H. Ashbaugh are committed to improving local K-12 education and have established a service learning course at the New Orleans Charter Science and Mathematics (NOCSM) High School. The demography of the school closely parallels that of the community, with 85% being from households classified as economically disadvantaged, and 86% of the student population belonging to a minority (82% African American). The outreach program was designed to present every day uses of the scientific method through presentation made by Tulane students followed up with experiments to illuminate the nature of the demonstrated phenomenon, like the rheological properties of biopolymers and the operation of heat engines. V. John has been a consistent participant of the LAMP (Louisiana Alliance for Minority Participation in Research) program for the last 8 years supervising one or two students every summer while N. Pesika will begin participation in the LAMP program over the summer. These minority students are typically from the minority institutions in the state (Xavier, Southern, Grambling State) or from non-minority New Orleans institutions including Tulane. We plan to apply for REU supplements which will be leveraged through the LAMP program.