#weekendusers Getting to the bottom of bones with new instrument


Osteoporosis affects millions of patients around the world and is characterised by a reduction of bone strength that results in increased rates of fractures. The irreversible mechanical behaviour of bone is currently well characterised at the organ level. The behaviour of mineralised collagen fibres, bone’s fundamental building block, remains a challenge for researchers. This weekend, scientists from Heriot-Watt University (United Kingdom), University of Bern, Empa (both in Switzerland), the CNRS and University Grenoble Alpes (France) and the ESRF will try to unveil those properties.

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I arrive at the beamline to find five scientists glued to the screens, in a passionate discussion in three different languages, French, English and German. One of the screens shows the beam, while another one shows the in situ microindentation instrument developed by the team and the ESRF to study the samples, in this case mineralised collagen fibrils (which make up fibre in bones). It is Friday morning and there is a long weekend ahead of a hopefully successful experiment. This is only the beginning.


The team. First row next to the desk, from bottom up: Jakob Schwiedrzik, Michael Sztucki, Aurelien Gourrier. Back row, from bottom up, Alexander Groetsch, Uwe Wolfram.

“It is the very first time we use this indenter in a diffraction beamline, so we need some time to set it all up and the samples are quite costly”, explains Uwe Wolfram, leader of the group, from Heriot-Watt University in Edinburgh (UK). Each specimen, originating from tendon and 6 times 12 µm in size,  is priceless due to the expensive preparation techniques and the long preparation time. No one has previously managed to provide insight into the irreversible mechanical properties of mineralised collagen fibrils with such a unique experimental setup because there was no way of studying them without having interference on to the results due to porosity, cracks, and other existing heterogenities in bone’s structure-mechanics hierarchy.


The indenter.


The indenter combined with the unique capabilities of ID13 overcomes this difficulty and allows the study of fibrils of 100 nanometres diametre. It applies load to the samples to study the stiffness and strength of an individual fibre. Combining this with Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Diffraction (WAXD) measurements on ID13 should show the deformations in the collagen network (SAXS) and in the mineral platelets (SAXS/WAXD). The indenter has been specifically developed through a European collaboration of the four institutes in the UK, Switzerland and France, as well as the ESRF. “It would not have been possible to be here today if we hadn´t worked all together in the last year, it has been a very important joint effort”, explains Wolfram.

The team intends to study the fibrils with the indenter. Ultimately, the researchers expect to be able to contribute to the development of personalised treatment and diagnoses strategies for bone-related illnesses or even engineering of bones artificially.

Text by Montserrat Capellas Espuny

Top image: Image taken with a light microscope during the preparation process. Credits: Alexander Groetsch