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Understanding the Interactions of Collagen with Mineral in Bone:
Working Towards Developing a Realistic CompositeF.J. Harden1, I.R. Gibson2, R.M. Aspden
3 and J.M.S. Skakle11Department of Physics, SUPA, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE2School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD
3 Musculoskeletal Programme, Institute of Medical Sciences, University of Aberdeen, Foresterhill, AB25 2ZD
Aims
• to review the existing literature on mineral-organic composites, focussing on the use of collagen;
• to study collagen in bone in situ to explore the mineral-collagen interaction;• to create and study new composite materials with similar features to bone.
What is bone and what are its functions?
� Bone is a light-weight, strong, living tissue.
� Bone contains its own cells and blood supply
surrounded by the interwoven bone structure.
� The bone extracellular matrix predominantly
consists of type I collagen (organic phase), and
hydroxyapatite (a mineral phase).
The main functions of bone are:
� to provide and maintain mechanical support
of the human body;
� to protect organs and vital tissues;
� to be a mineral reservoir around the body.
Bibliography• Ficai A. et al., Chem Eng. 2010;160:794-800.• Yin Hsu F., Chueh S, Jiin Wang Y. Biomaterials 1999; 20:1931-1936.• Williams D., Materials Today 2004;7:24-29.• Nam K. et al., Acta Biomaterialia 2010;6:409-417.• Wahl D.A., Czernuszka J.T., Eur. Cells Mater 2006;11:43-56.• Thian E.S. et al., Biomaterials 2005; 26:2947-2956.• Porter A.E. et al. 2003;24:4609-4620.• Hing K.A. et al., Biomaterials 2006;27:5014-5026.• Notingher I. et al., J Mol. Struct. 2005;744-747:179-185.
Figure 1: Raman spectra of bone alongside Raman spectra of HA and
substituted-HA, both heated at 1000oC for 2 hours
Requirements of a bone-substitute material:
� Biocompatible
� Osteoconductive
� Osteoinductive
� Bone regenerative
Why research bone replacement materials?
� Growth of elderly population as a percentage of
total population.
� Greater expectations of quality of life.
� Degenerative bone diseases.
� Bone graft demand exceeds available supply.
X-ray Powder Diffraction (XRD)
Used to determine if a sample is pure and provides
information on crystallinity and particle size. It is useful
for the analysis of the mineral component in bone and
the synthetic analogues.
Future Work
• Formulation and analysis of HA-based composites.
• Mini-project on bone nodule formation.
• Neutron scattering on whole bone.
• Analysis of bone explants using Raman spectroscopy.
Raman Spectroscopy
The Raman spectrum obtained can give valuable
information on a material’s chemical composition. It can be
used for determining specific chemical groups in a material
easily, quickly and with little material preparation.
Figure 3: Comparison of whale bone and as-prepared HA
(at room temperature)
Figure 2: XRD comparison of heated bone, HA and substituted-HA
Materials
Hydroxyapatite (HA) based materials are widely used in orthopaedics and dentistry. Bone is a multi-substituted
calcium-phosphate apatite with several ionic substitutions. Hence, substituted-HA improves the bioactivity and bone
apposition rate of a replacement material, as it provides a closer bone-like inorganic chemical composition with the
addition of substituted elements.
Type I collagen is effectively the main element in the ‘building blocks’ of the bone matrix and is used as a biomaterial
to mimic the extracellular matrix.
as-prepared HA
Whale bone
substituted-HA heated at 1000oC for 2 hours
HA heated at 1000oC for 2 hours
Whale bone heated at 1000oC for 2 hours
matrix
Techniques include:
Raman Spectroscopy and X-ray Powder Diffraction.
Email: [email protected]