Raman spectroscopy reveals differences in collagen secondary structure which relate to the levels of mineralisation in bones that have evolved for different functions

Authors

  • Kevin Buckley,

    1. UCL Institute of Orthopaedics and Musculoskeletal Science, Stanmore Campus, Royal National Orthopaedic Hospital, Middlesex, UK
    2. Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Oxfordshire, UK
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  • Pavel Matousek,

    1. Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Oxfordshire, UK
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  • Anthony W. Parker,

    1. Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Oxfordshire, UK
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  • Allen E. Goodship

    Corresponding author
    • UCL Institute of Orthopaedics and Musculoskeletal Science, Stanmore Campus, Royal National Orthopaedic Hospital, Middlesex, UK
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Allen Goodship, UCL Institute of Orthopaedics and Musculoskeletal Science, Stanmore Campus, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, UK.

E-mail: a.goodship@ucl.ac.uk

Abstract

Bone is a composite material comprising a collagen fibril scaffold surrounded by crystals of carbonated-hydroxyapatite mineral. It is well established that the relative proportions of mineral and collagen in mature bone are not definite and are adapted in order to ‘tune’ its mechanical properties. It is not known, however, how the mineral to collagen ratio is controlled. This paper uses Raman spectroscopy (which permits the probing of both the mineral and the collagen phases of bone) to explore the hypothesis that the control mechanism is related to the nature of the collagen and that bones with different levels of mineralisation have qualitatively different collagen. Raman spectra of functionally adapted bones with varying levels of mineralisation are presented and features that indicate the differences in the collagen's secondary structure (amide I band profiles) and post-translational modification (hydroxyproline/proline ratios) are highlighted. The study demonstrates that Raman spectroscopy can provide a means to investigate the mechanisms that control the mineral to collagen ratio of bone. Understanding these mechanisms could pave the way towards the therapeutic alteration of the mineral to collagen ratio and, thus, the control of the mechanical properties of bone. Copyright © 2012 John Wiley & Sons, Ltd.

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