Polychaete worm jaws - protein and metal for hard material

The jaws of the polychaete worm species Glycera and Nereis consist of mainly protein with a few percent of metal, copper and zinc, respectively. Yet, nanoindentation experiments have shown that their resistance to wear (ratio hardness to stiffness) even exceeds that of heavily mineralized biomaterials such as enamel and dentin in vertebrates. Glycera jaws have been found to owe their hardness partially to reinforcement by copper containing mineral crystallites. Additional copper in Glycera jaws and the zinc in Nereis jaws, however, appear to be bound directly to the jaw protein. In the second year of this post-doctoral project, the structural and mechanical characterization of polychaete jaws will be continued and work on a biomimetic analogue that imitates their favourable mechanical properties will be started. Synchrotron techniques such as microdiffraction and anomalous small angle x-ray scattering shall be used to determine the crystallographic orientation (texture) and outer shape of the mineral crystallites in Glycera jaws. X-ray absorption experiments will be continued to investigate the chemical environment of the metal in Nereis and Glycera jaws, complemented by electron spin resonsance (ESR) and x-ray photoelectron spectroscopy (XPS). This information shall be used as a basis for biomimicking of the material at the Materials Research Lab, UCSB. Biomimetic films will be characterized by x-ray scattering and spectrosopic techniques. Mechanical characterization by nanoindentation will be done in the framework of an already started collaboration with the applicant`s home institution, the Erich Schmid Institute, Austrian Academy of Sciences.