Biomineral Displays Systematic Spatially Varying Crystallographic Properties in Fibrolamellar Bone As Revealed by Position Resolved X-ray Diffraction.

Bone contains diverse structures. In fast-growing large animals, fibrolamellar bone is formed first and is then gradually replaced by remodelled bone with secondary osteons. Using position-resolved X-ray diffraction and X-ray fluorescence as a 2D multimodal microscopy technique, the nature of biomineral nanocrystals is investigated in bovine bone. Systematic spatial variations are found, for example, with the crystallite size increasing with distance from the bone growth front. The growth front is found to be sharply enriched in Zn, which is speculated to be related to the presence of metal-containing enzymes. Upon remodelling, the formed secondary osteons have a lower degree of mineralization, different lattice constants, and smaller nanocrystal sizes than the primary bone. The results underline the need for spatially resolved techniques for understanding bone biomineralization.