Precipitation of hydroxyapatite film under dynamic conditions

Hydroxyapatite was synthesized by reacting Ca(HCO₃)₂ with (NH)₂HPO₄ at 25°C. It was demonstrated that, for the crystallization of hydroxyapatite on a substrate as a coating, it is important to suppress the homogeneous nucleation in the bulk volume of the precursor solution. Heterogeneous nucleation on a sol-gel derived SiO₂ surface was advantageous for the deposition of film on a substrate under dynamic conditions. This approach led to the formation of a homogeneous, transparent coating (approx. 1 μm) of hydroxyapatite on the sol-gel derived SiO₂ surface on the glass.