Invertebrate cutting and piercing structures are highlighted by their lightweight construction, robust mechanical properties, and novel hardening mechanisms. The mechanical properties of these structures often surpass those of synthetic polymers and can be comparable to mineralized composite tissues found in higher organisms, underscoring their potential as models for advanced polymer systems. Our group has in particular investigated proteins isolated from the sclerotized jaw structures of the marine worm, <i>Nereis virens</i> (Nvjp-1) and the giant squid sucker ring teeth assembly (suckerin-12). We have achieved gram scale expression and column-less purification of these proteins enabling investigation of hierarchical ion exposure on sclerotization of these proteins. Interestingly, while both proteins shows a dramatic increase in modulus, the mechanism required for sclerotization are drastically different. With Nvjp-1, it was found that a hierarchical sequence of ion treatments was capable of modulating the mechanical properties of the hydrogels. The sequential exposure of Nvjp-1 hydrogels to certain anions and cations was found to yield dramatic increases (&gt;100 fold) in elastic modulus.  As with Nvjp-1 hydrogels, exposure of the suckerin-12 hydrogels to salts induced a significant decrease in hydrogel size where bulk water was driven out and condensation of the protein hydrogel occurred. Interestingly, the contraction rate as well as the mechanical properties of the condensed hydrogels were greatly dependent on the type of anion present in the salt. The differences observed in the mechanical properties of suckerin-12 hydrogels did not seem to be explained by changes in secondary structure or an increase in crystallinity, but correlated with the presence or absence of microstructures as measured by SEM. Therefore, the ability to dramatically tailor the mechanical properties of polymers through the incorporation of an ionic “dopant” allows for the potential to create structures and materials with graded and reconfigurable mechanical properties.<br/>

Tuning mechanical properties of marine biopolymers

254th National Meeting (2017)

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