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1 9 I H I G H L I G H T S 2 0 2 3

PRINCIPAL PUBLICATION AND AUTHORS

The elasto-plastic nano- and microscale compressive behaviour of rehydrated mineralised collagen fibres, A. Groetsch (a), A. Gourrier (b), D. Casari (c), J. Schwiedrzik (c), J.D. Shephard (d), J. Michler (c), P.K. Zysset (e), U. Wolfram (a), Acta Biomater. 164, 332-345 (2023); https:/doi.org/10.1016/j.actbio.2023.03.041 (a) Institute of Mechanical, Process & Energy Engineering, School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh (UK) (b) CNRS, LIPhy, Université Grenoble Alpes, Grenoble (France) (c) Empa, Swiss Federal Laboratories for Materials Science and Technology, Thun (Switzerland) (d) Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot- Watt University, Edinburgh (UK) (e) ARTORG Centre for Biomedical Engineering Research, University of Bern (Switzerland)

REFERENCES

[1] J. Schwiedrzik et al., Nat. Mater. 13, 740-747 (2014). [2] A. Groetsch et al., Acta Biomater. 89, 313-329 (2019). [3] A. Groetsch et al., Sci. Rep. 11, 15539 (2021). [4] A.G. Reisinger et al., Biomech. Model. Mechanobiol. 9, 499-510 (2010). [5] U. Wolfram & J. Schwiedrzik, BoneKEy Rep. 5, 1-10 (2016).

strength between mineralised tissues seem not to depend on rehydration. A lack of kink bands was observed, which supports the role of water as an elastic embedding that influences energy-absorption mechanisms.

Overall, these results suggest a high influence of hydration on ultrastructural interfaces and the role of water as an elastic embedding. This is concluded by outlining important differences between wet and dry elasto-plastic properties of mineral nanocrystals, fibrils and fibres. These results help to better understand the elasto-plastic behaviour of bone tissue at these small length scales. This work was supported by the UK Engineering and Physical Sciences Research Council and the Swiss National Science Foundation.

Fig. 7: Graphical abstract on methods and results: (a) illustrates how scattering experiment (top) and micromechanical testing (bottom) were combined. b) SAXS and XRD data (top) were interpreted using a statistical constitutive model

(bottom) that represented the micropillar specimens. c) This combination was used to investigate strain distributions (top) and conclude on mechanical properties such as yield strength, yield strain and stiffness (bottom).