Variations in bone biomineral properties revealed by sub-micron resolution X-ray fluorescence and diffraction tomography

Publikation: KonferencebidragPosterForskning

The structure of biomineralized materials is often complex and their study calls for methods with sensitivity across several length scales that can probe structures in 3D. Synchrotron X-ray tomographies with different contrast mechanisms, each providing unique position-resolved information, are emerging as key tools in the study of complex materials [1]. Here we have applied X-ray fluorescence and diffraction computed tomography to investigate the variation of biomineral properties across human osteonal bone. Bone, a biological material of vital importance in vertebrates, is a hierarchical composite with essential structural features ranging from the nanoscale to the anatomical scale. These structures, and especially how the nanoscale structures relate to the whole bone properties, remain poorly understood. The osteon is a main building block in human long bones and contributes to highly anisotropic mechanical properties. The osteon is a cylindrical structure with lamellae of mineralized collagen fibrils arranged in a plywood-like manner around a central blood vessel canal. It has been shown that this arrangement gives rise to periodically varying indentation modulus that correlates with the Ca content [2]. It is unclear whether the mineral crystallographic properties vary across the osteon and to which degree, if any, such variations impact properties. Using X-ray fluorescence and diffraction computed tomography to obtain position-resolved X-ray fluorescence spectra and diffractograms, respectively, we have investigated the distribution of elements and variation of crystallographic properties across the osteon using a 400 nm diameter X-ray beam to provide sub-µm resolution for the first time. The fluorescence showed a distinct increase in Ca content in interstitial bone compared to osteonal bone and a higher level of Sr in interstitial bone compared to inside the osteon. The >3.5 million reconstructed diffractograms were Rietveld refined with MultiRef [3] and revealed interesting variations with distance from the osteon center, as well as in the cell-associated bone, of several crystallographic parameters. [1] Birkbak et al. (2015) Nanoscale 7, 18402-18410. [2] Gupta et al. (2006) J. Mater. Res. 21, 1913-1921 . [3] Frølich & Birkedal (2015) J. Appl. Cryst. 48, 2019-2025.
Udgivelsesår28 jul. 2018
StatusUdgivet - 28 jul. 2018
BegivenhedGRC Biomineralization - , USA
Varighed: 28 jul. 20183 aug. 2018


KonferenceGRC Biomineralization

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