MS17-P03 Multi-scale characterization of bone mineral composition and structural organizationBone is a complex biocomposite material constituted by carbonated apatite nanocrystals deposited in an oriented fashion and integrated within an organic matrix, mostly collagen fibrils. To define how bone compositional and structural characteristics in different bone types (i.e. cortical and trabecular bone) affect relevant bone properties (i.e., mechanical properties), we have applied complementary analytical techniques such as electron microscopy, computed tomography, infrared spectroscopy and X ray diffraction. These techniques provide detailed information about the mineral and organic components of bone tissue and allow the determination of its porosity, degree of mineralization, carbonate content, mineral crystallinity and collagen cross-linking. Bone compositional parameters determined by infrared spectroscopy (e.g. degree of mineralization (PO4/Amide I), the total carbonate (CO4_1415/Amide I) are important parameters to define bone material quality and are useful to detect possible metabolic alterations associated to specific bone pathological conditions (osteoporosis, osteomalicia). BSE-SEM images of cross-section at mid-diaphysis showed notable differences in the organization of different bone types (cortical and trabecular bone) and bone structures at different scales. Analyses by means 2D X-ray diffraction showed differences between types of bone related to mineral organization and its crystallinity. The degree of alignment of the c-axis of apatite crystals can be determined from the intensity profile along Debye-Scherrer ring associated with the 002 reflection. The preferential orientation of the apatite crystals is due to an aligned arrangement of collagen fibers in cortical organization while the crystals showed randomly orientation at trabecular level. The information obtained allowed us to determine the influence of chemical composition and microstructural organization on cortical and trabecular regions in the overall bone material properties.
Keywords: bone, organization, microstructure