UBC Theses and Dissertations
The mystery of the whelk egg capsule protein : electrospinning, mechanical testing, and being outsmarted by an invertebrate Corbett, Carla M.
Whelks are carnivorous marine snails known for their elaborate and durable egg capsules. The mechanically complex capsules have been previously studied, and shown to have mechanical behaviour similar to keratin. The mature protein has an initial stiff linear elastic region at low strain, followed by a rubbery yield region with a fully repeatable order of magnitude decrease in stiffness. The material properties of the protein mature in distinct stages, with long-range elasticity developing first, followed by the development of the stiff Hookean region. As the capsule matures, it is massaged by a gland in the foot of the snail, which probably enables cross-linking. This study sought to mimic the development process using electrospinning to create fibres with charge-based assembly, then adding a cross-linking step to encourage the stiff spring behaviour to form. An electrospinning protocol was developed and parameters were optimized. The technique was applied successfully, and the resulting protein nanofibres could be cross-linked. The electrospun protein fibres were shown to have composition and secondary structures similar to the native protein. However, the mechanical properties of the cross-linked nanofibres were more similar to a transitional stage in the egg capsule’s maturation sequence than they were to the mature capsule. The fibres did not exhibit the bimodal behaviour seen in the native polymer.
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