Synthesis of hydroxyapatite on silica gel surface by using glycerin as a drying control chemical additive

Synthetic hydroxyapatite (HAP) was grown on surface of silica gels by immersing silica monoliths in a simulated body fluid at room temperature (37 °C). The gels were prepared by the sol-gel method and the drying process was controlled by using different organic additives (mono- and diethylene glycol, formamide and glycerin) to obtain large monoliths. Ca/P molar ratios were estimated, X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR) were performed to determine the phase analysis and functional group composition, respectively. Further, the surface morphology of the silica gels was studied by scanning electron microscopy (SEM). The formation of HAP competes with the formation of crystalline calcium carbonate, but the results indicate optimisation of conditions for the growth of the former as a function of the type and concentration of the additive.