In vitro synthesis of bioactive hydroxyapatite using sodium hyaluronate as a template

Being a biocompatible and bioactive material, hyaluronic acid has great potential as a template to regulate the mineralization of hydroxyapatite (HA) nanocrystals in vitro. Our present study investigates the effects of sodium hyaluronate (SH) concentrations and initial pH values on the chemical composition, morphology and biological properties of hydroxyapatite (HA) crystals prepared by the wet chemical approach. All purified products were studied by Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), X-ray photo-electronic spectroscopy (XPS), and transmission electron microscopy (TEM). This is the first time that bioactive carbonated apatites were synthesized using SH as a template. Biocompatibility of such apatites was gauged by cell vitality and alkaline phosphatase activity of MG-63 cells. The results suggested that carbonated apatites synthesized in the presence of SH were more favorable to the proliferation and differentiation of MG-63 cells compared to conventional apatites. In our study, we also found that SH temporarily stabilizes amorphous calcium phosphate (ACP) at the early stage of crystallization. The results imply that the initial pH value and the concentration of SH play a key role in affecting calcium vacancies, carbonate content and morphology of apatite crystals, as well as their effects on the proliferation and osteogenic differentiation of MG-63 cells. These synthesized carbonate-containing apatites are potentially attractive candidates for tissue engineering applications.