Comparative biomechanics of intermediate filaments

仿生学是一个不断发展的科学领域，它从生物结构和过程中获得灵感来设计新的产品。最著名的仿生成功故事是魔术贴，它的灵感来自于微小的钩子，可以让毛刺搭乘动物毛皮。在我的实验室里进行的仿生研究集中在由生物体制造的结构材料上，这种材料可能会激发具有独特和有用特性的新合成材料的发明。在我的博士研究中，我从事的是一种纤维材料，这种材料出现在八目鳗的防御性粘液中，八目鳗是一种生活在海底的海洋食腐动物。我发现，这些纤维虽然在天然状态下柔软而有弹性，但可以很容易地加工成具有类似蜘蛛丝的性能的纤维，蜘蛛丝以其卓越的强度和韧性而闻名。这些实验导致了一项专利申请(目前正在审查中)，并打开了一扇窗，让人们了解一组被称为“中间纤维”(或IF)的纤维蛋白质的结构和性质。这些纳米级的蛋白质细丝存在于粘液线中，构成了大多数动物细胞细胞骨架的重要组成部分。它们也构成了哺乳动物制造的更常见的被称为角蛋白的物质的主体，包括柔软的皮肤外层和更坚硬的结构，如头发、指甲和角。通过使用由几乎纯净的IF束组成的鳗鱼粘液线，我能够制定一个详细的模型，可以解释动物使用IF制造的材料的巨大多样性。这个模型对细胞和角质蛋白中的IF的行为做出了几个预测。这里提出的这项研究的短期目标是通过检查模型中一些最关键的预测来测试和改进模型。要做到这一点，我们将使用基于IF的各种方便的材料，包括八目鳗粘液线、神经、马蹄和鲸须。这项研究的长期目标是提炼出基于IF的材料的一些设计原则，并将它们应用于提供生态可持续性和优越性能的工业材料的设计。

Biomimetics is a growing scientific field that takes inspiration from biological structures and processes for the design of novel products. The most famous biomimetic success story is Velcro®, which was inspired by the tiny hooks that allow burrs to hitch a ride on animal fur. The biomimetic research carried out in my lab focuses on structural materials made by organisms that could potentially inspire the invention of new synthetic materials with unique and useful properties. For my Ph.D. research, I worked on a fibrous material that occurs within the defensive slime of the hagfish, a bottom-dwelling marine scavenger. I discovered that these fibres, although soft and stretchy in their native state, could be easily processed into fibres with properties similar to spider silk, which is renowned for its superior strength and toughness. These experiments led to a patent application (which is currently under examination), and also opened a window into the structure and properties of a group of fibrous proteins called "intermediate filaments" (or IFs). These nano-scale protein filaments occur in slime threads and make up an important part of the cytoskeleton of most animal cells. They also form the bulk of the more familiar materials made by mammals called "keratins," which include the soft outer layer of skin and harder structures like hair, nail, and horn. Working with hagfish slime threads, which consist of nearly pure bundles of IFs,  I was able to formulate a detailed model that can explain the large diversity of materials that animals make using IFs. This model makes several predictions about the behavior of IFs in cells and keratins. The short-term goal of the research proposed here is to test and refine the model by examining some of its most critical predictions. To do this, we will use a variety of convenient materials that are based on IFs, including hagfish slime threads, nerves, horse hoof, and whale baleen. The long-term aim of this research is to distill out some of the design principles of IF-based materials, and apply them to the design of industrial materials that deliver both ecological sustainability and superior performance.