Biomimetic transformations of amorphous calcium phosphate: kinetic and thermodynamic studies
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The biomimetic synthesis and phase transformation of XRD amorphous calcium phosphate were studied by application of kinetic, chemical and spectral (XRD and IR) methods and thermodynamic simulations. Two SBFs (SBFc and SBFr), differing in their HCO3 − and Cl− ion contents, were used in the maturation studies. It has been proven that the biomimetic maturation accelerated the phase transformation of less thermodynamically stable amorphous calcium phosphate to poorly crystalline hydroxyapatite. Several regularities have been found: (i) kinetic reasons determined the biomimetic precipitation of XRD-amorphous calcium deficient phosphate (ACP); (ii) the precipitated ACP always contained impurities due to co-precipitation, ion substitution and incorporation phenomena; (iii) the increased content of HCO3 − ions in the surrounding microenvironments increased the rate of phase transformation and the concentration of MeHCO3 + (Me = Ca, Mg) species in the solution, but the solubility of CaCO3 has only been decreased and its precipitation accelerated, thus playing a crucial role in the process under study.
KeywordsHCO3 Calcium Phosphate Simulated Body Fluid Amorphous Calcium Phosphate MgCO3
This work is financially supported by the Bulgarian Ministry of Education, Youth and Science under Projects DO-02-82/2008 and X-1509.
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