Solid-State NMR Study of the Transformation of Octacalcium Phosphate to Hydroxyapatite: A Mechanistic Model for Central Dark Line Formation.
For many years, octacalcium phosphate (OCP) has been postulated as the precursor phase of biological apatite in bones and teeth. In this work, we study the molecular mechanism of OCP to hydroxyapatite (HAp) transformation in vitro by several physical techniques, with particular emphasis on solid-sta...
| Publicado en: | Journal of the American Chemical Society Vol. 128; no. 21; pp. 6909 - 6919 |
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| Autores principales: | , , |
| Formato: | Artículo |
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American Chemical Society
5/31/2006
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=21306316&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 21306316 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 5/31/2006 vid: 128 iid: 21 pid: 997 pub: American Chemical Society artinfo: ui: 21306316 10.1021/ja060336u ppf: 6909 ppct: 10 formats: tig: atl: Solid-State NMR Study of the Transformation of Octacalcium Phosphate to Hydroxyapatite: A Mechanistic Model for Central Dark Line Formation. aug: au: Yao-Hung Tseng Chung-Yuan Mou Chan, Jerry C. C. affil: Department of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei, Taiwan Center of Condensed Matter, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei, Taiwan su: Hydroxyapatite Apatite Phosphates Nuclear magnetic resonance Solid state chemistry Physical & theoretical chemistry sug: subj: Hydroxyapatite Apatite Phosphates Nuclear magnetic resonance Solid state chemistry Physical & theoretical chemistry ab: For many years, octacalcium phosphate (OCP) has been postulated as the precursor phase of biological apatite in bones and teeth. In this work, we study the molecular mechanism of OCP to hydroxyapatite (HAp) transformation in vitro by several physical techniques, with particular emphasis on solid-state P homonuclear double-quantum (DQ) NMR spectroscopy. The in vitro system is prepared by mixing urea, sodium phosphate monobasic dehydrate, and calcium nitrate tetrahydrate at 100 °C. The images obtained by scanning electron microscopy and transmission electron microscopy show that the bladelike OCP crystals will transform into hexagonal rod-shaped HAp crystals as the pH of the reaction mixture increases slowly from 4.35 to 6.69 in 12 h. Powder X-ray diffraction patterns indicate that a trace amount of monetite was also precipitated when the pH was around 5. Together with computer-assisted lattice matching, our DQ NMR data reveal that OCP crystals transform to HAp topotaxially, where the [0001] and [2110] axes are along the same directions as the [001] and [010] axes, respectively. On the basis of our in vitro results, the formation of the central dark line commonly found in biological hard tissues could be explained by the inherent lattice mismatch between OCP and HAp. Furthermore, the data of the P{1H} cross-polarization NMR suggest that water molecules enter the hydration layers of OCP crystals via the hydrolysis reaction HPO + OH = PO + HO, which also accounts for the deprotonation of the HPO ions during the transformation. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2006 holdings: @attributes: islocal: N |
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