Biological light-weight cutting devices: Structure investigations on worm jaws using X-ray scattering, X-ray spectroscopy and AFM techniques

The optimization of biological materials on particular functions like water conduction, load bearing and enzymatic functions etc. has made researchers think of mimicking nature to produce smaller electronic devices, more efficient signal transmission, more lightweight constructions etc. The main objective of the present post-doctoral project is to investigate the structure of a very strong and tough biological lightweight material of peculiar composition: the jaws of clam worms (Nereis) that contain a few percent of zinc (Zn). Although the jaw is not mineralized and, apart from Zn, consists of mainly protein, the material exhibits an extraordinarily high fracture energy. The main question is how the low proportion of Zn is organized within the jaw structure so that it results in considerably improving the hardness and toughness of the material. The first step towards an understanding of the structure of Nereis jaws will be attempted using position resolved X- ray scattering techniques. The experiments will be started in the X-ray laboratory of the host institution and, if a higher position resolution is required, be continued with synchrotron radiation. The spectroscopic techniques of Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near-Edge Structure (XANES) will be used on extracted proteins to determine whether Zn actually binds to one of the jaw proteins and in which way. Nanoindentation will be performed on Nereis jaws to study the correlation between local Zn concentration and local hardness. The project is designed for one year and will be entirely dedicated to the study of the biological material. However, the long term goal of these investigations is to go further and use the knowledge obtained to produce a biomimetic analogue of Nereis jaws material via self assembly of extracted and recombined proteins and Zn. The group of Galen D. Stucky at the Department of Chemistry and Biochemistry, University of California Santa Barbara (UCSB), has an excellent international reputation in the field biomimetic materials. Extensive use will be made of experimental facilities at the host institute as well as the synchrotron radiation facilites at Argonne National Laboratory (ANL). Biological and biomimetic materials have become of increasing interest in recent years also in Austria. The scientific and technical potential of such materials, however, is still hardly explored. The present project shall contribute to the advancement of research in this field and help to keep science in Austria up to date with recent developments.