Induction and morphology of hydroxyapatite, precipitated from metastable simulated body fluids on sol-gel prepared silica.
Hydroxyapatite crystallization is induced at 37 degrees C by sol-gel prepared silica from metastable calcium phosphate solutions. The morphology of the apatite forming on the silica surface depends on the nature of the solutions. For example, apatite grew in a flake-like form at pH 7.4. The morphology changed to plate-like when the pH was adjusted to pH 7.2. At this lower pH, the apatite plate even exhibited a hexagonal feature, reflecting the unique hexagonal structure of hydroxyapatite. An increase in either Mg or P ion concentration of the fluid can cause apatite to grow in a rod-like shape while addition of F ions to the fluid leads to a perfect needle pattern. The flake geometry of apatite was not altered by increasing Ca concentration from 2.5 to 3.8 mM in the solution. From this we conclude that sol-gel prepared silica is an efficient apatite inducer and the morphology of the hydroxyapatite deposit is determined by factors of the fluid such as pH, Ca/P molar ratio, Mg and F concentrations.
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Department of Biomaterials, School of Medicine, University of Leiden, The Netherlands.
Nakanishi
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Kokubo
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de Groot
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D001826:Body Fluids / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010758:Phosphorus / Q000737:chemistry; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D013696:Temperature
D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; D010758:Phosphorus; D058428:Silica Gel; C485838:calcium phosphate, monobasic, anhydrous; D012822:Silicon Dioxide; D017886:Durapatite; C020243:calcium phosphate; D008274:Magnesium; C485829:calcium phosphate, dibasic, anhydrous