| Title | Structural analysis of Si-substituted hydroxyapatite: Zeta potential and X-ray photoelectron spectroscopy |
| Publication Type | Journal Article |
| 2002 |
| Authors | Botelho, CM, Lopes, MA, Gibson, IR, Best, SM, Santos, JD |
| Journal | Journal of Materials Science: Materials in MedicineJ. Mater. Sci. Mater. Med. |
| Volume | 13 |
| Issue | 12 |
| Pagination | 1123 - 1127 |
| Date Published | 2002/// |
| 09574530 (ISSN) |
| calcium oxide, calcium phosphate, Chemical modification, conference paper, crystal structure, Dissolution, Electric Potential, electricity, hydroxyapatite, in vitro study, isoelectric point, Lime, molecular dynamics, pH, pH measurement, phase transition, phosphate, Phosphorus Compounds, priority journal, reaction analysis, Silicon, Silicon compounds, silicon derivative, structure analysis, surface property, X ray photoelectron spectroscopy, Zeta potential |
| The aim of this study was to determine the effect of the incorporation of silicon on the surface charge of hydroxyapatite (HA) and to assess surface structural changes of HA and Si-HA induced by dissolution in both static and dynamic systems. X-ray photoelectron spectroscopy (XPS) analysis showed that SiO 4
4- groups were substituted for PO
4
3- groups in the silicon-hydroxyapatite (Si-HA) lattice according to a previously proposed substitution mechanism without the formation of other crystalline phases, such as tricalcium phosphate or calcium oxide. The substituted silicon induced a decrease in the net surface charge and the isoelectric point of HA as determined by zeta potential (ZP) measurements. At physiological pH = 7.4 the surface charge of Si-HA was significantly lowered compared to unmodified HA, i.e. -50 ±5 to - 71 ± 5 eV, caused by the presence of silicate groups in the HA lattice, which may account for a faster in vitro apatite formation using SBF testing. XPS results indicated that silicon seems to be preferentially leached out from Si-HA surface compared to other ionic species after dissolution studies in tris-buffer using a dynamic system. © 2002 Kluwer Academic Publishers.
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