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Towards a model of the mineral–organic interface in bone: NMR of the structure of synthetic glycosaminoglycan‐ and polyaspartate‐calcium phosphate composites
Author(s) -
Best Serena M.,
Duer Melinda J.,
Reid David G.,
Wise Erica R.,
Zou Shuo
Publication year - 2008
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2168
Subject(s) - chemistry , magic angle spinning , mineral , crystallography , phosphate , molecule , nuclear magnetic resonance spectroscopy , nmr spectra database , stereochemistry , organic chemistry , spectral line , physics , astronomy
We have synthesised three materials–chondroitin sulphate (ChS, a commercial product derived from shark cartilage and predominantly chondroitin‐6‐sulphate (Ch‐6‐S)) bound to pre‐formed hydroxyapatite (HA, Ca 10 (PO 4 ) 6 (OH) 2 ), HA formed in the presence of ChS and poly‐Asp bound to pre‐formed HA–to generate models for the mineral–organic interface in bone. The three materials have been investigated by 13 C cross polarisation magic‐angle spinning (CPMAS) NMR, 13 C{ 31 P} rotational echo double resonance (REDOR) and powder x‐ray diffraction (XRD) in order to verify their composition and to determine the nature of their binding to HA. Our results show that for HA formed in the presence of Ch‐6‐S, all carbon atoms in the Ch‐6‐S having contact with mineral phosphate. We propose that HA in this case forms all around the Ch‐6‐S polymer rather than along one face of it as is more commonly supposed in cases of templating by organic molecules. However, Ch‐6‐S binding to pre‐formed HA probably occurs via a surface layer of water on the mineral rather than to the mineral directly. In contrast, poly‐Asp binds closely to the pre‐formed HA surface and so is clearly able to displace at least some of the surface‐bound water. Copyright © 2008 John Wiley & Sons, Ltd.