Grant: Discovery Grants Program - Individual

Polymer fibres are used in a wide range of applications from fabrics to composites for construction, filtering devices, batteries, drug delivery devices and wound care. These fibres are generally produced from petrochemicals and tend to degrade very slowly, if at all, accumulating in our environment at an alarming rate. The long-term goal of my research program is to develop fibres with mechanical properties comparable to synthetic polymers by unlocking the use of naturally occurring biopolymers, especially protein waste from agricultural and food industries. We will focus on zein, a corn protein deficient in essential amino acids for human nutrition, and collagen, the main structural protein of animals found in their skin and a main waste of the meat and fish processing industry. Currently these proteins can be processed into fibres using standard approaches such as wet-spinning or electrospinning. Both techniques are limited in term of scalability and yield fibres with structural and mechanical properties of low quality that are often unsuitable for industrial or medical applications. This research program will explore one potential alternative, contact drawing. This method is inspired by the way caterpillars spin silk, one of the strongest natural fibres with mechanical properties superior to the strongest synthetic fibres. By inserting a pin into a viscous concentrated solution of large molecules, typically a polymer, and quickly removing it, one can form a long and thin liquid bridge that dries into a fibre. For concentrated polymer solutions, we have shown that polymer chains entanglement is a key requirement for fibre formation even in the presence of a protein additive like collagen. For collagen/polymer fibres, polymer removal leads to collagen self-assembly into fibres with tunable mechanical properties and potential for tissue engineering applications. We recently characterized the structure of these fibres but the mechanism controlling their assembly is currently unknown. For concentrated protein solutions such as zein, contact drawing was just recently demonstrated in our lab for the first time and is simply not understood at all. Our goal is to fill these knowledge gaps by exploring how protein-protein and protein-polymer interactions in the liquid state couple with contact-drawing parameters such as pulling speed to produce fibres with unique molecular structure and exceptional mechanical properties. Our approach combines a broad range of structural techniques across length scales such as electron microscopy, atomic force microscopy, vibrational spectroscopy and X-ray scattering along with mechanical testing and computer simulations. Overall, our findings have a great potential to lead to the design and production of biodegradable, high performance, protein fibres for a broad range of applications including new scaffolds for tendon repair.