Identifying the Irreversible Mechanical Behaviour of Individual Mineralised Collagen Fibril Assemblies
Lead Research Organisation:
Heriot-Watt University
Department Name: Sch of Engineering and Physical Science
Abstract
Osteoporosis and osteoarthritis affect millions of patients around the world and are eventually characterised by a reduction of bone strength that results in increased rates of fractures. Life expectancy continues to rise but patient specific treatment solutions to optimally manage those patients are sill not available. Such solutions could consist of tailored medication strategies and, at a later stage, tailored implant solutions which require a thorough understanding of the mechancial competence of structural tissue. While the mechanical behaviour of bone is currently well characterised at the upper level of tissue organisation, the underlying nonlinear mechanical properties of mineralised collagen fibre assemblies, however, remain obscured by structural features such as cellular porosity, lamellar organisation, cement lines, cracks and other interfaces. Starting from preliminary pilot experiments, this proposal aims at performing simultaneous uniaxial micropillar strength tests and structural measurements using small-angle X-ray scattering and wide-angle X-ray diffraction on micron-sized volumes of the extra-cellular matrix (ECM) and, thus, on mineralised collagen fibre assemblies only. This project will result in a versatile and powerful experimental framework that will be used to understand the structure-mechanics relation of ECM with an unprecedented spatial resolution of the mechanical experiment. The results of this project will inform the engineering of patient-specific material solutions in silico through all relevant length scales starting from the ECM level. This, in turn, will foster the development and realisation of production technologies for manufacturing patient-specific "implants on demand" which could be offered as a service or embedded in a hospital. The novel experimental techniques may be useful for testing and developing functional thin films such as implant coatings, investigating the impact of pathological changes on the ECM, or even to reduce, refine, and replace animal experiments.
Planned Impact
Society: As an ageing society UK is highly affected since over 11 million (approximately 17 %) inhabitants suffer from osteoporosis or osteoarthritis. Osteoporosis itself is associated with a dramatic increase in mortality and it causes women beyond menopause to spend more days in hospital than due to diabetes, heart attack or breast cancer. The diseases would be highly manageable if diagnostics, treatments, and compliance could be improved. A corner stone could be the development of patient specific diagnoses and treatment strategies. Those strategies necessarily rely on a thorough understanding of structure-mechanics relationships of the affected tissues at the extra-cellular matrix level. The present project makes a major contribution to this end.
Science: Simultaneous uniaxial strength tests and X-ray diffraction measurements on micron-sized volumes of the extra-cellular matrix are a breakthrough to understand biological hard tissues. The proposed experiments are a new technical challenge that could be extended to a much broader class of biological, biomimetic and non-biological composites and nanostructured materials. It will lead directly to novel questions and challenges on different tissue types both healthy and subject to pathological changes.
Specifically targeting bone in such a challenging project will help to understand the mechanical behaviour of the fundamental building blocks of bone and the scale transition of bone mechanical properties beyond the elastic loading regime in general. This is a prerequisite to develop optimal strategies for diagnosis, treatment, and the management of patients with musculoskeletal diseases. The results will have a direct and substantial impact in my field of research and will inform a broad audience of researchers ranging from theoretical and experimental biomechanics, through tissue engineering and synthetic biology, to pre-clinical and clinical orthopaedics.
Technology: The versatile and powerful experimental framework developed at the core of this project will be of use for a wide range of researchers crossing disciplines from geoscience, to biomedical and energy engineering, materials science, to functional coatings and optical materials. This will be realised through the collaborations within this project and then by making the novel experimental framework available for new scientific and industrial collaborations.
Science: Simultaneous uniaxial strength tests and X-ray diffraction measurements on micron-sized volumes of the extra-cellular matrix are a breakthrough to understand biological hard tissues. The proposed experiments are a new technical challenge that could be extended to a much broader class of biological, biomimetic and non-biological composites and nanostructured materials. It will lead directly to novel questions and challenges on different tissue types both healthy and subject to pathological changes.
Specifically targeting bone in such a challenging project will help to understand the mechanical behaviour of the fundamental building blocks of bone and the scale transition of bone mechanical properties beyond the elastic loading regime in general. This is a prerequisite to develop optimal strategies for diagnosis, treatment, and the management of patients with musculoskeletal diseases. The results will have a direct and substantial impact in my field of research and will inform a broad audience of researchers ranging from theoretical and experimental biomechanics, through tissue engineering and synthetic biology, to pre-clinical and clinical orthopaedics.
Technology: The versatile and powerful experimental framework developed at the core of this project will be of use for a wide range of researchers crossing disciplines from geoscience, to biomedical and energy engineering, materials science, to functional coatings and optical materials. This will be realised through the collaborations within this project and then by making the novel experimental framework available for new scientific and industrial collaborations.
Organisations
- Heriot-Watt University (Lead Research Organisation)
- European Synchrotron Radiation Facility (Collaboration)
- University of Bern (Collaboration)
- University of Grenoble (Collaboration)
- Joseph Fourier University (Project Partner)
- Danaher (Sweden) (Project Partner)
- University of Bern (Project Partner)
- NHS GREATER GLASGOW AND CLYDE (Project Partner)
Publications
Alexander Groetsch
(2020)
The micro- and nanoscale compressive behaviour of rehydrated mineralised collagen fibres
Groetsch A
(2019)
Compressive behaviour of uniaxially aligned individual mineralised collagen fibres at the micro- and nanoscale.
in Acta biomaterialia
Groetsch A
(2023)
The elasto-plastic nano- and microscale compressive behaviour of rehydrated mineralised collagen fibres.
in Acta biomaterialia
Groetsch A
(2021)
An experimentally informed statistical elasto-plastic mineralised collagen fibre model at the micrometre and nanometre lengthscale.
in Scientific reports
Hennige S
(2020)
Crumbling Reefs and Cold-Water Coral Habitat Loss in a Future Ocean: Evidence of "Coralporosis" as an Indicator of Habitat Integrity
in Frontiers in Marine Science
McPhee S
(2021)
Heat impact during laser ablation extraction of mineralised tissue micropillars.
in Scientific reports
McPhee S
(2023)
QCT-based computational bone strength assessment updated with MRI-derived 'hidden' microporosity.
in Journal of the mechanical behavior of biomedical materials
Samuel McPhee
(2021)
Heat impact during laser 1 ablation extraction of mineralised tissue 2 micropillars
in Scientific Reports
Schwiedrizk JJ
(2018)
Nanoscale deformation mechanisms and yield properties of hydrated lamellar bone.
Speed A
(2020)
Extrafibrillar matrix yield stress and failure envelopes for mineralised collagen fibril arrays.
in Journal of the mechanical behavior of biomedical materials
Wolfram U
(2022)
Multiscale mechanical consequences of ocean acidification for cold-water corals.
in Scientific reports
Title | Life as a Coral |
Description | See also narrative impact. This product is a science and engineering-inspired drama workshop for 3-7 year olds called Life as a Coral. This workshop takes approximately one and a half hours to complete and requires a clear space for children to move around such as a gym hall. Using drama exercises this workshop explores the topics of the coral reefs of Scotland, the scientists and engineers helping them and what they can do themselves to help the environment. By using story and drama as a format the children act out the information as they process it using imaginative play, movement and group-work. Life as a Coral is part of a wider project called Let's Do Engineering through Heriot-Watt University and is designed to get young children to learn about the jobs that engineers play in our world. This workshop is based on research by Heriot-Watt researcher Dr. Uwe Wolfram and was created by theatremaker and science communicator Lisa Wilson |
Type Of Art | Performance (Music, Dance, Drama, etc) |
Year Produced | 2021 |
Impact | Product has been provided to pre-schools as teaching material within a wider project called Let's Do Engineering through Heriot-Watt University and is designed to get young children to learn about the jobs that engineers play in our world. |
Description | We successfully implemented novel experimental techniques combining micropillar compression testing with simultaneous X-ray diffraction techniques. This allows to probe micron-sized volumes in a uniaxial fashion and supplement such measurements with deformation measurements on the nanometre length scale. In the course of the project this setup will be used to investigate scale transitions of the strains in mineralised tissues such as bone. Using a uniaxial model system, i.e. mineralised turkey leg tendon, we aim at unravelling the irreversible behaviour of mineralised collagen fibrils. In addition, we developed imaging methods to image tested micropillars in 3D at a spatial resolution of up to 10 nm. We have developed a novel constitutive model that explains the micro- and nanomechanical behaviour of mineralised collagen fibres. We used both the developed experimental techniques and the model to investigate this behaviour under wet, quasi-phyisologic conditions. |
Exploitation Route | The whole setup is portable and can be implemented in diffraction beamlines at synchrotrons other than the European Synchrotron Radiation Facility. Furthermore, it is an integral part of our own hierarchical material mechanics laboratory. Currently, the results form critical data for two larger proposals. One in the environmental sciences and one in engineering. The developed model together with the identified data are freely available and pave the way to formulate a unified model for bone tissue. |
Sectors | Aerospace Defence and Marine Environment Healthcare Manufacturing including Industrial Biotechology Pharmaceuticals and Medical Biotechnology Other |
Description | The methods and tools have been instrumental to obtain data on cold-water coral skeletons and this data fed directly into the design of a drama workshop for pre-school children. The workshop is part of a wider project called Let's Do Engineering through Heriot-Watt University and is designed to get young children to learn about the jobs that engineers play in our world. The title of the drama workshop is 'Life as a Coral' and and the workshop strives to realise a science and engineering-inspired drama workshop for 3-7 year olds. Using drama exercises this workshop explores the topics of the coral reefs of Scotland, the scientists and engineers helping them and what they can do themselves to help the environment. By using story and drama as a format the children act out the information as they process it using imaginative play, movement and group-work. This workshop is based on research by Heriot-Watt researcher Dr. Uwe Wolfram and was created by theatremaker and science communicator Lisa Wilson. Without the methods and tools we have developed in this project, our cold-water coral research would not have materialised and this workshop as well as funding by the Leverhulme Trust (RPG-2020-215, PI Dr. Uwe Wolfram) and a number of exciting research manuscripts would not have been possible. |
Sector | Education,Environment,Healthcare,Culture, Heritage, Museums and Collections |
Impact Types | Societal |
Description | Standard beam time application |
Amount | € 43,000 (EUR) |
Funding ID | ME-1458 |
Organisation | European Synchrotron Radiation Facility |
Sector | Charity/Non Profit |
Country | France |
Start | 12/2017 |
End | 12/2017 |
Description | Standard beam time application |
Amount | € 43,000 (EUR) |
Funding ID | ME-1472 |
Organisation | European Synchrotron Radiation Facility |
Sector | Charity/Non Profit |
Country | France |
Start | 08/2017 |
End | 09/2017 |
Description | Standard beam time application |
Amount | € 43,000 (EUR) |
Funding ID | ME-1415 |
Organisation | European Synchrotron Radiation Facility |
Sector | Charity/Non Profit |
Country | France |
Start | 07/2016 |
End | 08/2016 |
Title | A statistical constitutive model for the micro- and nanomechanical behaviour of mineralised collagen fibres |
Description | Computational models could be a cornerstone in digital healthcare to tackle the socio-economic burden associated with bone-related diseases such as osteoporosis, osteoarthritis and bone cancer. This includes improved diagnoses, the manufacturing of custom implants and the monitoring of bone implant systems in personalised medicine. Such models strongly depend on understanding the complex characteristics of bone as a material on its different hierarchical levels. To address this, we need a comprehensive modelling framework that is able to simulate the nonlinear mechanical behaviour of bone tissue from the molecular up to the macroscopic length scale. There is, however, still limited knowledge on the mineralised collagen fibre. This fibre is a fibril-matrix reinforced composite and bone's mechanical building block at the microscale consisting of mineralised collagen fibrils and mineral particles. Here, we report an elasto-plastic statistical constitutive model that bridges the gap between the nano- and micrometre length scale and by quantifying average collagen deformations may connect continuum and molecular levels. By embedding two shear lag models, we can explain the mineralised collagen fibre behaviour and how load is transferred between its main mechanical components. We used experimental results at the fibre level from combining micropillar compression and X-ray scattering. Furthermore, synchrotron radiation X-ray phase-contrast nanometre computed tomography was used to quantify the ultrastructure of the fibril-matrix composite. The model outputs statistical distributions for micro- and nanomechanical responses including strain ratios between the fibre and its components, e.g. deformations of the mineralised collagen fibrils and mineral particles. As such, it directly simulates results from combined mechanical testing and X-ray scattering analyses of composite materials. Heterogeneous fibril deformation helps to explain small strain ratios independently reported for mineralised tissues in such experiments. The model achieves a mean accuracy of 96% compared to micro- and nanoscale experiments. To assess the generality of our model, we validated it against independent results for bone extracellular matrix. Our model explains bone's fundamental microscale mechanical unit and closes a gap between molecular and continuum levels. Our model helps to understand nonlinear bone mechanics and is generally applicable for fibril-reinforced composites that can be used in the design of bio-inspired materials. |
Type Of Material | Model of mechanisms or symptoms - human |
Year Produced | 2019 |
Provided To Others? | Yes |
Impact | See description above |
Title | Facilitating micropillar testing under physiological conditions |
Description | After successfully combining micropillar testting, a method to probe micron sized volumes of extra-cellular matrix, with small- and wide angle X-ray diffraction, we extended the mehtod to allow for testing under quasi-physiological conditions. This allows to measure strains in the molecular network of a micron sized specimen of extra-cellular matrix closer to the actual properties of the living tissue. |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2018 |
Provided To Others? | Yes |
Impact | Novel experimental procedure established at beamline ID13 of the European Synchrotron Radiation Facility. As method and devices are portable, this can be used at, e.g., Diamond light source. |
Title | In situ micropillar compression test in SAXS/WAXD synchrotron beamline |
Description | We combined micropillar testting, a method to probe micron sized volumes of extra-cellular matrix, with small- and wide angle X-ray diffraction for the first time. This allows to measure strains in the molecular network of a micron sized specimen of extra-cellular matrix and extends the compression test on the micrometer length scale to deliver answers on the molecular level. |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2016 |
Provided To Others? | Yes |
Impact | Novel experimental procedure established at beamline ID13 of the European Synchrotron Radiation Facility. |
Title | Synchrotron nanoCT analyses for mineralised collagen fibrils |
Description | Developed novel scanning to resolve individual mineralised collagen fibres (~7 µm diameter 14 µm height) at 20 nm spatial resolution. Developed novel analyses protocols to estimate number of mineralised collagen fibrils in fibre. |
Type Of Material | Physiological assessment or outcome measure |
Year Produced | 2018 |
Provided To Others? | No |
Impact | novel ultra-high resolution imaging protocol to be used for mineralised tissues is generally accessible for synchrotron users Manuscript in preparation |
Description | Dry micropillar compression SAXS/WAXD experiments |
Organisation | European Synchrotron Radiation Facility |
Country | France |
Sector | Charity/Non Profit |
PI Contribution | We performed micropillar compression experiments on micron-sized samples combined with SAXS/WAXD measurements. This was possible |
Collaborator Contribution | The team of ID13 provided support in writing the beam time application. Do to its successful acceptance full hands on support of the whole team during our experiment was given. |
Impact | Novel experimental scheme (micropillar testing combined with SAXS/WAXD for the first time) 1st experimental report |
Start Year | 2015 |
Description | SAXS/WAXD evaluation |
Organisation | University of Grenoble |
Department | Laboratory for Interdisciplinary Physics |
Country | France |
Sector | Academic/University |
PI Contribution | A team member has been travelling to Grenoble to get training in the evaluation of SAXS/WAXD signals and to start the experimental evaluation. The successful experiment at ID13 of the European Synchrotron Radiation Facility (ESRF) has opened up new routes for testing and will foster additional experiments with this group. |
Collaborator Contribution | University of Grenoble provides full hands on training in the evaluation of SAXS and WAXD signals acquired in step-wise loading experiments conducted at ID13 (ESRF). |
Impact | step-wise loading experiment at ID13 of joint evaluation of mechanical, SAXS and WAXD data |
Start Year | 2016 |
Description | Sample preparation |
Organisation | University of Bern |
Country | Switzerland |
Sector | Academic/University |
PI Contribution | The team from Heriot-Watt travelled to Bern to prepare the necessary test specimens for the grant. This was necessary since the laboratory facilities at Heriot-Watt were under construction when the project started. A team member stayed for four weeks to accomplish the production of 200 specimens for the micromechanical tests. |
Collaborator Contribution | The team of the ISTB provided access to their preparation facility and stored the raw material. Most importantly their workshop produced 200 high precision sample holders that had a suitable accuracy to be used in synchrotron light nano-computed tomography that could not have been produced otherwise. |
Impact | 200 high-precision sample holders for SEM, FIB/SEM, and synchrotron light nano-computed tomography 200 pre-specimens for further preparation in SEM |
Start Year | 2016 |
Description | BBC Worldservices interviews |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Recorded an interview on 24/09/2017 giving brief background of the project and its aims. Live interview 25/09/2017 BBC breakfast radio giving brief background of the project and its aims. |
Year(s) Of Engagement Activity | 2017 |