Bioinspired and Biological Chitin and Chitosan Based Composites -- Chemistry, Microstructure and Mineralization

Thesis (Ph.D.)--University of Washington, 2017-06From the stiffness span of squid beaks to the toughness of seashells and the hardness of chiton teeth, natural biological materials have a broad range of exceptional mechanical properties. Tanning induced protein cross-linking dictates the transition from the stiff rostrum to the compliant wing of a squid beak. A highly ordered microstructural organization of chitin nanofiber network embedded within a protein matrix facilitates the toughness of seashells. Nano-crystalline magnetite minerals embedded within chitin nanofiber network gives the ultra hardness of chiton tooth. Inspired by these biological strategies for improved mechanical properties, my Ph.D. research has been focusing on engineering chitin and chitosan based composites with improved mechanical properties from chemistry, microstructure and mineralization. Projects include a squid beak mimics with stiffness span dictated by the degree of cross-linking, methods to control chitin-silk molecular morphology including an electric-field assisted gelation method and a water vapor annealing method as well as a proof-of-concept chitin-GelMA hydrogel for tissue engineering applications, and using banana slug radula as a model to explore correlations from teeth morphology, chemical composition and mineralization, to mechanical behavior and functionalities