SSNMR confirms silicate ion substitution in the apatitic structure of 0.8wt% Si hydroxyapatite
This study investigates the structural location of silicon present in ‘silicate-substituted’ apatite. It has been hypothesized that silicon is present in the form of silicate groups site-specifically substituted in the hydroxyapatite lattice for phosphate groups, or that there may be an a...
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Academia.edu Journals
2023-11-01
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| Series: | Academia Materials Science |
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| author | Marc-Krystelle Mafina Rory M. Wilson Gregory J. Rees Peter Gierth Alice C. Sullivan Karin A. Hing |
| author_facet | Marc-Krystelle Mafina Rory M. Wilson Gregory J. Rees Peter Gierth Alice C. Sullivan Karin A. Hing |
| author_sort | Marc-Krystelle Mafina |
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This study investigates the structural location of silicon present in ‘silicate-substituted’ apatite. It has been hypothesized that silicon is present in the form of silicate groups site-specifically substituted in the hydroxyapatite lattice for phosphate groups, or that there may be an amorphous silicon-rich phase in the vicinity of the grain boundaries. Solid-state nuclear magnetic resonance (SSNMR) spectroscopy was carried out to view the elemental interactions using phosphorus (31P) and silicon (29Si) probes to confirm or refute the presence of silicate groups in relation to phosphate groups in the bulk material structure. The analysis was performed on stoichiometric hydroxyapatite (HA) and silicate-substituted hydroxyapatite (SA) with a nominal silicon content of 0.8wt%, in as-precipitated, calcined (700°C), and sintered (1,250 and 1,300°C, respectively) powder forms. XRD confirmed all forms of powder were phase pure. FTIR confirmed both hydroxyl and phosphate group functionalities in all forms of HA and SA, while silicate group functionality was only observed in all forms of SA. SSNMR using 31P- and 29Si-coupled probes demonstrated that as the crystallinity of the powders increased from the precipitate to the sintered form, the signal associated with the presence of a silicate group in the phosphate environment developed as the crystal structure became more ordered. These results support the hypothesis that in SA containing 0.8wt% silicon, silicate groups are site-specifically substituted in the hydroxyapatite lattice for phosphate groups. This observation may be key to understanding the mechanisms by which the introduction of 0.8wt% silicon enhances bone regeneration in apatitic bone graft substitute materials. |
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| institution | Kabale University |
| issn | 2997-2027 |
| language | English |
| publishDate | 2023-11-01 |
| publisher | Academia.edu Journals |
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| series | Academia Materials Science |
| spelling | doaj-art-2659b0d4ae7d41b091d0b0e5c1af871f2025-02-11T21:54:44ZengAcademia.edu JournalsAcademia Materials Science2997-20272023-11-011110.20935/AcadMatSci6121SSNMR confirms silicate ion substitution in the apatitic structure of 0.8wt% Si hydroxyapatiteMarc-Krystelle Mafina0Rory M. Wilson1Gregory J. Rees2Peter Gierth3Alice C. Sullivan4Karin A. Hing5PerkinElmer AES (UK) Ltd, Buckinghamshire HP9 2FX, United Kingdom.X-ray Diffraction Facility, Centre for Materials Research, Queen Mary University of London, London E1 4NS, United Kingdom.Materials NMR/MRI, University of Oxford, Oxfordshire OX1 2JD, United Kingdom.Bruker Biospin, NMR Centre, Coventry CV4 9GH, United Kingdom.School of Biological and Chemical Science, Queen Mary University of London, London E1 4NS, United Kingdom.School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, United Kingdom. This study investigates the structural location of silicon present in ‘silicate-substituted’ apatite. It has been hypothesized that silicon is present in the form of silicate groups site-specifically substituted in the hydroxyapatite lattice for phosphate groups, or that there may be an amorphous silicon-rich phase in the vicinity of the grain boundaries. Solid-state nuclear magnetic resonance (SSNMR) spectroscopy was carried out to view the elemental interactions using phosphorus (31P) and silicon (29Si) probes to confirm or refute the presence of silicate groups in relation to phosphate groups in the bulk material structure. The analysis was performed on stoichiometric hydroxyapatite (HA) and silicate-substituted hydroxyapatite (SA) with a nominal silicon content of 0.8wt%, in as-precipitated, calcined (700°C), and sintered (1,250 and 1,300°C, respectively) powder forms. XRD confirmed all forms of powder were phase pure. FTIR confirmed both hydroxyl and phosphate group functionalities in all forms of HA and SA, while silicate group functionality was only observed in all forms of SA. SSNMR using 31P- and 29Si-coupled probes demonstrated that as the crystallinity of the powders increased from the precipitate to the sintered form, the signal associated with the presence of a silicate group in the phosphate environment developed as the crystal structure became more ordered. These results support the hypothesis that in SA containing 0.8wt% silicon, silicate groups are site-specifically substituted in the hydroxyapatite lattice for phosphate groups. This observation may be key to understanding the mechanisms by which the introduction of 0.8wt% silicon enhances bone regeneration in apatitic bone graft substitute materials.https://www.academia.edu/108926570/SSNMR_confirms_silicate_ion_substitution_in_the_apatitic_structure_of_0_8wt_Si_hydroxyapatite |
| spellingShingle | Marc-Krystelle Mafina Rory M. Wilson Gregory J. Rees Peter Gierth Alice C. Sullivan Karin A. Hing SSNMR confirms silicate ion substitution in the apatitic structure of 0.8wt% Si hydroxyapatite Academia Materials Science |
| title | SSNMR confirms silicate ion substitution in the apatitic structure of 0.8wt% Si hydroxyapatite |
| title_full | SSNMR confirms silicate ion substitution in the apatitic structure of 0.8wt% Si hydroxyapatite |
| title_fullStr | SSNMR confirms silicate ion substitution in the apatitic structure of 0.8wt% Si hydroxyapatite |
| title_full_unstemmed | SSNMR confirms silicate ion substitution in the apatitic structure of 0.8wt% Si hydroxyapatite |
| title_short | SSNMR confirms silicate ion substitution in the apatitic structure of 0.8wt% Si hydroxyapatite |
| title_sort | ssnmr confirms silicate ion substitution in the apatitic structure of 0 8wt si hydroxyapatite |
| url | https://www.academia.edu/108926570/SSNMR_confirms_silicate_ion_substitution_in_the_apatitic_structure_of_0_8wt_Si_hydroxyapatite |
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