Hierarchical chitinous matrices byssus-inspired with mechanical properties tunable by Fe(III) and oxidation

In this study the multi-scale hierarchical structure of the β-chitin matrix from squid pen of Loligo vulgaris was used as substrate to synthesize new bio-inspired materials. Aiming to mimic the byssus peculiar mechanical properties, we chemically functionalized the β-chitin matrix with catechols, one of the main functional groups of the byssus. The obtained matrix preserved its multi-scale structural organization and was able to chelate reversibly Fe(III). Thus, it behaved as the byssus, acting as a metal cross-linkable matrix that upon metalation increased its Young's modulus, E (>10 times). The functionalized matrix was also cross-linked by oxidation provoking an increase of the E (>10 times) and first failure stress (>5 times). The oxidation of the functionalized matrix followed by metalation slightly increased the material mechanical properties. In conclusion, we added specific bio-functionalities in a natural matrix tuning its mechanical properties without altering its multi-scale organization.