Centimetre- to nanometre-scale exploration of biomineral structure

Speaker: Dr Jeremy Shaw –  CMCA@Physics, University of Western Australia

Venue   : Thu 28 April 2016 – 4pm (Murdoch University, Senate Conference Room)

The iron biomineralised teeth of marine chitons are organic/inorganic composite structures that are built using hierarchically ordered components that span multiple length scales. Understanding the mechanisms governing the highly controlled bio-fabrication of these natural structures is necessary for inspiring the design of novel advanced materials. This study utilises a range of imaging techniques to journey from the level of the whole organism down to the nanoscale structural components that underpin the material properties of these remarkable structures.

Whole tooth anatomy was explored using a combination of optical microscopy and X-ray micro-computed tomography, which provide a means to digitally examine structure/function relationships at the centimetre- to micrometre-scale. The composite organic and mineral sub-structure of the teeth was observed using a combination of SEM-based serial sectioning (3-view and focused ion beam milling) and electron tomography, which reveal micrometre- to nanometre-scale detail of hierarchical components.

The teeth are shown to be comprised of a network of organic fibres that are arranged in a comparable orientation to the final mineralised product. These fibres are also shown to persist throughout the mineralisation process, but may be displaced or fragmented by the growing mineral phase. Fibres are also shown to pass through multiple mineral phases, which may impart structural and functional properties superior to the mineral in isolation. The fibre network and mineral architecture of the tooth as a whole are arranged in a manner that matches the feeding mechanics proposed for this species of chiton.

The multi-scale data generated by these various imaging modalities has revealed insights into the growth and design of these hierarchically structured biominerals. The provision of a final blueprint of the entire fibre network that underlies chiton tooth structure will facilitate the interpretation of fibre/mineral structure across a range of lengths scales in future studies.