Novel mechanisms of strain energy dissipation in collagen polymers: their characterization, control, and application

胶原聚合物应变能耗散的新机制：其表征、控制和应用

• 批准号: RGPIN-2014-04967
• 负责人: Veres, Samuel
• 金额: $ 1.82万
• 依托单位: Saint Mary's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=638095
• 关键词: Novel; mechanisms; strain; energy; dissipation

Toughness is a highly desirable material property, combining both strength and fracture resistance. In addition to being very strong, tough materials can also undergo considerable deformation before breaking. Ongoing research to create tough materials has led to the development of a wide variety of metallic alloys and engineered composites. However, the toughness of these materials is achieved through a limited number of “toughening mechanisms”, most of which we have known about for decades. Because toughness is such a desirable material property, identifying new toughening mechanisms could drive the development of a wide range of new engineering materials. The aim of this research program is to identify new toughening mechanisms by studying a remarkable biomaterial: the collagen fibril. Collagen fibrils are the most common—and important—structural biomaterial within humans and almost all other animals. Collagen fibrils are biological cables that are nearly 1000 times smaller in diameter than a human hair. They are what gives strength to your tendons, ligaments, bones, skin, arteries, heart valves, cartilage, and more. In addition to being very strong, collagen fibrils are also very tough: approximately 10 times tougher than steel wire. Yet, despite their incredible material properties, the toughening mechanisms that function within collagen fibrils have not yet been identified.In the first part of this research program, the nanoscale structure of both collagen fibrils and the molecules that they are composed of will be studied before and after mechanical overload. Using tools such as transmission electron microscopy, with which magnifications of up to 300,000x are possible, we will attempt to determine what makes collagen fibrils tough. In the second part of the research program, we will study different types of collagen fibrils to try and determine: (i) if some fibrils are tougher than others, and (ii) if so, what structural characteristics account for this difference. We will also chemically modify collagen fibrils, artificially joining or breaking apart the collagen molecules contained within to see how these changes alter toughness. In the final part of this research program, we will use the information that we have gathered in parts one and two to build new, high-performance, biodegradable materials. We will work toward building new bandages and wound dressings that are soft and bendable when applied, but then harden giving superior protection to the healing tissue beneath. We will also work toward building new composite materials by impregnating collagen fibrils with minerals. We will use these new composite materials to develop new, resorbable surgical implants. For repairing a badly fractured bone, for example, a collagen-based implant could provide the structural support required during healing and then slowly disappear, being broken down and absorbed by the body.While this work will take many years to complete, the results, even from the project’s early stages, will be important to many people. Tissue engineers will be able to use our results to improve the mechanical performance of their laboratory-built tendons, ligaments, skin, and arteries. Discovering ways to make these engineered tissues tougher would help bring them to market, benefiting the thousands of Canadians each year who require surgeries involving artificial or allograft tissue. After learning what happens to collagen fibrils and their molecules when overloaded, doctors and surgeons may think of better ways to treat sprains and strains, or ways to accelerate connective tissue healing. And finally, material scientists may be able to use the unique toughening mechanisms that we discover to develop a whole range of new materials for everyday use.

韧性是一种非常理想的材料性能，兼具强度和抗断裂性能。除了非常坚固之外，坚韧的材料在断裂之前也会经历相当大的变形。正在进行的创造坚韧材料的研究已经导致了各种金属合金和工程复合材料的发展。然而，这些材料的韧性是通过有限数量的“增韧机制”实现的，其中大部分我们几十年前就知道了。由于韧性是一种非常理想的材料特性，因此，确定新的增韧机制可以推动一系列新工程材料的发展。这项研究计划的目的是通过研究一种非凡的生物材料：胶原纤维来确定新的增韧机制。胶原纤维是人类和几乎所有其他动物中最常见也是最重要的结构生物材料。胶原蛋白纤维是一种生物电缆，直径几乎是人类头发的1000倍。它们给你的肌腱、韧带、骨骼、皮肤、动脉、心脏瓣膜、软骨等提供力量。除了非常坚固，胶原纤维也非常坚韧：大约比钢丝坚韧10倍。然而，尽管它们具有令人难以置信的材料特性，但在胶原纤维中发挥作用的增韧机制尚未被识别。在本研究计划的第一部分，将研究机械过载前后胶原纤维及其组成分子的纳米结构。使用诸如透射式电子显微镜之类的工具，我们将尝试确定是什么使胶原纤维变得坚韧。在研究计划的第二部分，我们将研究不同类型的胶原纤维，试图确定：(I)某些纤维是否比其他纤维更坚韧，以及(Ii)如果是，是什么结构特征导致了这种差异。我们还将对胶原纤维进行化学修饰，人工连接或分离包含在其中的胶原分子，看看这些变化是如何改变韧性的。在这个研究计划的最后部分，我们将使用我们在第一部分和第二部分中收集的信息来构建新的、高性能的、可生物降解的材料。我们将致力于建造新的绷带和伤口敷料，这些绷带和伤口敷料在使用时是柔软和可弯曲的，但随后会变硬，为下面的愈合组织提供更好的保护。我们还将致力于通过在胶原纤维中浸渍矿物质来构建新的复合材料。我们将使用这些新的复合材料开发新的、可吸收的外科植入物。例如，对于严重骨折的骨骼的修复，基于胶原蛋白的植入物可以提供愈合过程中所需的结构支持，然后慢慢消失，被身体分解和吸收。虽然这项工作需要多年的时间才能完成，但结果，即使是在项目的早期阶段，对许多人来说也是重要的。组织工程师将能够利用我们的结果来改善他们实验室建造的肌腱、韧带、皮肤和动脉的机械性能。找到让这些工程组织变得更坚韧的方法，将有助于将它们推向市场，使每年数以千计的加拿大人受益，他们需要接受涉及人造或同种异体组织的手术。在了解了超负荷时胶原纤维及其分子会发生什么之后，医生和外科医生可能会想出更好的方法来治疗扭伤和拉伤，或者加速结缔组织的愈合。最后，材料科学家可能能够使用我们发现的独特的增韧机制来开发一系列日常使用的新材料。