Parallel Mappings as a Key for Understanding the Bioinorganic Materials

Abstract

Important bioinorganic objects, both living and fossilized are as a rule characterized by a complex microscopic structure. For biological samples, the cell-like and laminar as well as growth ring structures are among most significant. Moreover, these objects belong to a now widely studied category of biominerals with composite, inorganic-organic structure. Such materials are composed of a limited number of inorganic compounds and several natural organic polymers. This apparently simple composition leads to an abnormal variety of constructions significant from the medical (repairs and implants), natural (ecological effectiveness) and material science (biomimetic synthesis) point of view. The analysis of an image obtained in an optical microscope, optionally in a scanning electron microscope is a topographical reference for further investigations. For the characterization of the distribution of chemical elements and compounds in a material, techniques such as X-ray, electronor proton microprobes are applied. Essentially, elemental mappings are collected in this stage. The need for the application of an X-ray diffraction microprobe is obvious and our experience indicates on the necessity of using the synchrotron-based devices due to their better spatial resolution and good X-ray intensity. To examine the presence of the organic compounds, the Raman microprobe measurements are good options. They deliver information about the spatial distribution of functional groups and oscillating fragments of molecules. For the comprehensive investigation of bioinorganic material structural and chemical features, we propose the following sequence of methods: optical imaging, elemental mapping, crystallographic mapping, organic mapping and micromechanical mapping. The examples of such an approach are given for: petrified wood, human teeth, and an ammonite shell.