Multiscale characterization of bone mineral : new perspectives in structural imaging using X-ray and electron diffraction contrast

Orateur : Soutenance de Thèse de Mariana VEREZHAK (LIPHY)

Bone tissue is a biological composite material for which a fundamental understanding of how the mineral structure is organized at different hierarchical length scales is of high importance for the biomedical community. The potential of novel methods currently developed for materials science applications was tested for bone analysis, including : coherent X-ray diffraction (CXDI), automated crystal orientation transmission electron microscopy (ACOM-TEM) and X-ray diffraction pair distribution function (PDF) analysis. Using this multiscale combination of techniques, bone tissue was investigated from its sub-angstrom arrangement, taking into account chemical composition and interatomic bond lengths shifts, through individual crystal structure and morphology to their organization with respect to the collagen microfibrils organization. Using a model system of heated bones which mineral nanocrystal structure and dimensions can be finely tuned and which are of interest in archaeology, anthropology and forensic science, we established a first proof-of concept for all methods. A restric ted set of pathological bone tissue was also investigated, for which specific structural pathological signatures were identified at the sub-angstrom scale. Those results therefore provide new perspectives for ultrastructural studies of bone tissue and for biological materials and biomaterials in a broader senses.

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