Comparative biomechanics of intermediate filaments

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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.