Element distributions and crystallographic properties of human bone at <140 nm resolution in 2D and 3D
Notice bibliographique
Résumé
Biomineralized tissue such as bone or shells often have a complex hierarchical 3D structure ranging over several length scales. To understand their structure, a method for probing the nanoscale structure in 3D is needed. Bone is particularly challenging due to its' many layers of hierarchical structure in combination with the complex system of osteocyte cells interconnected by canaliculi. Recent developments in synchrotron x-ray focusing optics afford minute x-ray beams, which open opportunities for probing structures at length scales smaller than ever before. Herein, we present how we probe the elemental distribution and crystallographic properties of human bone in 2D and 3D using combined fluorescence and diffraction scattering computed tomography (F-CT and DSCT) [1] with a 50 nm pencil X-ray beam. PURPOSE: This study aims to develop nanoscale 3D multimodal X-ray imaging with the purpose of studying the local chemistry around the mineralization front where new bone is formed, and around canaliculi. METHODS: We conducted multimodal tomography using a nanofocused <50 nm diameter X-ray beam. A 2.6x3.1 µm2 cross section rod-shaped sample was FIB-cut from human iliac crest bone. The sample was cut from an area close to an osteocyte and thus presents several canaliculi. We recorded 2D diffraction patterns and fluorescence spectra at each point in a 50 nm raster scan grid pattern. This was repeated for each of 92 projection angles covering 0-182°. This allowed us to reconstruct tomographically both x-ray diffraction patterns and the elemental composition in a ~5x5x3 µm3 volume encompassing the sample. We determined an upper estimate of the achieved resolution by fitting sharp features within the specimen. Secondly, we measured several 2D scans with the same beam size on several-micron thick human bone encompassing the mineralization front to shed light on the biomineralization process. RESULTS: We show that tomographic reconstruction of x-ray diffraction and fluorescence information is possible with these minute X-ray beams. The resolution was <140 nm estimated from features in reconstructed images indicating that the true resolution is in the 50-140 nm range. With this resolution we were able to clearly distinguish between canaliculi and solid bone based both on calcium fluorescence and mineral diffraction signals. On the 2D sample, we could follow the mineralization process and the spatial distribution of oligoelements such as zinc in relation thereto. CONCLUSIONS: This work show that biomineral crystalline structure and elemental composition can be studied in 3D at length scales an order of magnitude smaller than hitherto available in sample volumes of biological relevance. This method will allow studying biominerals in more detail than ever before especially around distinct structural features like osteocytes. [1] M. E. Birkbak, H. Leemreize, S. Frolich, S. R. Stock, H. Birkedal, Nanoscale 2015, 7, 18402.eon
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».