Hierarchy-induced X-ray linear dichroism in cortical bone
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ORIGINAL ARTICLE
Hierarchy-induced X-ray linear dichroism in cortical bone Aleksei S. Konashuk 1 & Xenia O. Brykalova 1 & Nikolai N. Kornilov 2 & Elena O. Filatova 1 & Andrey A. Pavlychev 1 Received: 21 January 2020 / Accepted: 30 April 2020 # Qatar University and Springer Nature Switzerland AG 2020
Abstract The high-resolution X-ray absorption spectra of rat tibia cortex have been measured for two different orientations of the bone long axis in respect to the electric field vector of linear polarized synchrotron radiation. Our measurements performed near the Ca 2p and O 1s absorption edges have revealed the substantial element-specific orientation dependence of the X-ray absorption coefficient. Strong changes in intensity of core-to-valence transitions are detected near the Ca L2,3 absorption edges, whereas minor changes occur near the O K absorption edge. The specific behavior is attributed to the emergent properties of X-ray linear dichroism in cortex. This optical phenomenon is assigned with relationship between the chemical Ca–O bonds in bone and hierarchical organization of the skeleton. The hierarchy-induced X-ray linear dichroism is discussed in the framework of the 3D superlattice model and Wolff paradigm. Prospects for using this phenomenon for medical diagnosis are also being discussed. Keywords Emergent properties . Chemical bonds in hierarchical nanostructures . Ca 2p and O 1s NEXAFS of cortex . Linear dichroism in bone . Hierarchical organization of the skeleton
1 Introduction Material science and biological and medical investigations disclose a complicated hierarchy of skeleton designs from macro- to nanolevels [1–10]. The nanoscopic research of bone tissue encounters great difficulties mainly because of qualitative character of the basic morphological models used to describe the skeletal structure–functional properties. Molecular architecture and electronic and atomic structures of bone tissue are not completely studied. This gap prevents succeeding in solution of many fundamental and applied problems such as development of new methods of medical imaging of bone at the subcellular level and medical diagnosis of skeletal pathology in the early stage. To solve these problems, the emergent properties of electronic and atomic structures of bone tissue induced by hierarchical organization of the skeleton have to be investigated.
* Andrey A. Pavlychev [email protected] 1
Solid State Electronics Department, St-Petersburg State University, St. Petersburg, Russia 198504
2
Vreden Russian Research Institute of Traumatology and Orthopedics, St. Petersburg, Russia 195427
Recently, the three-dimensional superlattice (3DSL) model was suggested to understand the interplay of short-, long-, and super-range order parameters in electronic and atomic structures of mineralized bone. The model describes the specific properties of hierarchical nanostructures electronics, such as the so-called hydroxyapatite (HAP)-to-bone shift of valence states [10]. At present, the shift is confirmed by comparing the exp
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