Revisiting silicate substituted hydroxyapatite by solid-state NMR

• Published in: Magnetic resonance in chemistry 2008-04, Vol.46 (4), p.342-346
• Main Authors: Gasquères, G., Bonhomme, C., Maquet, J., Babonneau, F., Hayakawa, S., Kanaya, T., Osaka, A.
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Durapatite - chemistry; hydroxyapatite; Inorganic chemistry; Isotopes; Magnetic Resonance Spectroscopy - methods; Magnetic Resonance Spectroscopy - standards; Models, Molecular; Powder Diffraction; Protons; Reference Standards; Silicates - chemistry; Silicon - chemistry; silicon-substituted HAp; solid-state NMR; Spectrophotometry, Infrared - methods; T1ρ(1H) edited 1H → 29Si CP MAS experiments
• ISSN: 0749-1581; 1097-458X
• DOI: 10.1002/mrc.2109

Silicon‐substituted hydroxyapatite (Si‐HAp) has shown promising properties such as high‐bone remodeling around implants. So far, the techniques used for the structural characterization of the Si‐HAp have given indirect evidence of the presence of silicon inside the structure (by X‐ray and neutron diffraction). In this paper, we focus on Si‐HAp derivatives obtained by a precipitation method (widely described in the literature). We demonstrate here by solid‐state NMR spectroscopy that only a fraction of the silicon atoms are incorporated into the HAp lattice in the form of Q0 (SiO44−) species, for 4.6 wt% Si‐HAp. A large amount of silicate units are located outside the HAp structure and correspond to silica‐gel units. All results were established through 29Si MAS, 1H →29Si CP MAS and T1ρ(1H) edited 1H →29Si CP MAS experiments. This last pulse scheme acted as a powerful editing sequence, leading to unambiguous spectroscopic conclusions, concerning the location of the SiO44− moieties. Copyright © 2008 John Wiley & Sons, Ltd.