EAGER: Slick Yet Stuck? Using Adhesion to Expose the Conditions of the Buried Cartilage Interface

EAGER：光滑但卡住？

• 批准号: 1937493
• 负责人: David Burris
• 金额: $ 28.95万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-12-01 至 2022-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1937493&HistoricalAwards=false
• 关键词: EAGER; Slick; Yet; Stuck; Using

Remarkable adhesive mechanisms have evolved across the animal kingdom to help jumping spiders stick a landing, octopi catch prey, geckos locomote on vertical surfaces, and clingfish grip slippery, bio-fouled rocks. In each of these distinct and well-studied cases, there were strong connections between adhesion and survival to drive the evolutionary process. This research team has recently discovered that cartilage, a material well-known for exceptionally low adhesive friction, generates exceptionally strong adhesive stresses -- comparable to those of the gecko, octopus, and clingfish. This finding is paradoxical, because friction and adhesion are fundamentally linked. Additionally, unlike other natural examples of strong adhesion, there is no obvious evolutionary pressure for strong joint adhesion. The fact that cartilage simultaneously exhibits both "super-lubricity" and "super-adhesion" violates long-standing assumptions about cartilage lubrication while exposing critical clues about the unusual underlying mechanics. This EArly-Concept Grant for Exploratory Research (EAGER) project seeks to resolve this "cartilage lubrication-adhesion" paradox. The results will: (1) clarify how tensile forces are generated in the joint and what that implies about joint lubrication; (2) provide original insights into bio-adhesion while exposing new directions for bio-inspiration and materials discovery; (3) lend insight into the causes and consequences of "joint cracking", a common, clinically important, and poorly understood phenomenon. If the understanding of cartilage functional mechanics are condensed into a single framework, it will inform substantially improved strategies to protect, treat, or replace compromised joints.The project will use novel interfacial tension measurements to quantify interfacial permeability, experimentally separate the contributions from adhesion (seen in the gecko) and suction (seen in the clingfish) mechanisms, and systematically assess the intersection between cartilage friction and adhesion across length scales. Using micro force microscopy, beam displacements from normal and friction forces will be quantified on an experimental indenter. Cartilage samples (osteochondral cores) will be obtained from bovine joints. Three aims have been developed. The first will isolate the effect of exudation on adhesion, suction, and interfacial gaps by varying the dwell time prior to pull-off to systematically vary interstitial fluid loss. The second aim will isolate and quantify adhesive forces by eliminating the contribution of suction, using quasistatic rates for the pull-off tests. The third aim will quantify the interfacial properties (e.g. sliding friction, effective contact modulus, equilibrium modulus, and fluid load fraction) across length scales by using varying probe radii, which will have varying effects on suction forces (dependent on radius) and adhesion forces (independent of radius).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

整个动物界都进化出了非凡的粘合机制，帮助跳跃的蜘蛛坚持着陆，章鱼捕捉猎物，壁虎在垂直表面移动，粘鱼抓住光滑的、被生物污染的岩石。在这些不同和研究充分的案例中，粘附性和存活率之间存在着强烈的联系，推动了进化过程。这个研究小组最近发现，软骨是一种以极低的粘合摩擦而闻名的材料，它会产生非常强的粘合应力--与壁虎、章鱼和粘鱼的粘附力相当。这一发现是矛盾的，因为摩擦和粘着从根本上是联系在一起的。此外，与其他强粘连的自然例子不同，关节强粘连没有明显的进化压力。软骨同时表现出“超润滑性”和“超粘附性”的事实违反了长期以来关于软骨润滑的假设，同时揭示了关于不寻常的潜在机制的关键线索。这个探索性研究的早期概念拨款(AGERGE)项目试图解决这一“软骨润滑-粘连”悖论。结果将：(1)阐明关节中张力是如何产生的，以及关节润滑意味着什么；(2)提供对生物粘连的原创性见解，同时揭示生物灵感和材料发现的新方向；(3)深入了解“关节破裂”的原因和后果，这是一种常见的、临床上重要的、但知之甚少的现象。如果将软骨功能力学的理解浓缩到一个单一的框架中，它将为保护、治疗或替换受损关节提供实质性改进的策略。该项目将使用新的界面张力测量来量化界面渗透性，通过实验分离粘连(在壁虎中看到)和吸力(在钳鱼中看到)机制的贡献，并系统地评估软骨摩擦和跨长度尺度的粘连之间的交集。利用微力显微镜，将在实验压头上量化来自法向力和摩擦力的梁的位移。软骨样本(骨软骨核)将从牛关节获得。已经制定了三个目标。第一种是通过改变拔出前的停留时间来系统地改变间质液体损失，从而隔离渗出对粘连、吸力和界面间隙的影响。第二个目标将通过消除吸力的贡献来分离和量化粘附力，使用准静态拉力测试。第三个目标将通过使用不同的探头半径来量化长度范围内的界面属性(例如滑动摩擦、有效接触模数、平衡模数和流体载荷分数)，这将对吸力(取决于半径)和附着力(与半径无关)产生不同的影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

The modes and competing rates of cartilage fluid loss and recovery

软骨液丢失和恢复的模式和竞争率

• DOI: 10.1016/j.actbio.2021.11.014
• 发表时间: 2021
• 期刊: Acta Biomaterialia
• 影响因子: 9.7
• 作者: Voinier, S.;Moore, A.C.;Benson, J.M.;Price, C.;Burris, D.L.
• 通讯作者: Burris, D.L.

Range-of-motion affects cartilage fluid load support: functional implications for prolonged inactivity

• DOI: 10.1016/j.joca.2020.11.005
• 发表时间: 2021-01-01
• 期刊: OSTEOARTHRITIS AND CARTILAGE
• 影响因子: 7
• 作者: Benson, J. M.;Kook, C.;Burris, D. L.
• 通讯作者: Burris, D. L.