Bioresorbability Evaluation of Hydroxyapatite Nanopowders in a Stimulated Body Fluid Medium

The bone mineral consists of tiny hydroxyapatite (HA) crystals in the nanoregime. Nanostructured HA is also expected to have better bioactivity than coarser crystals. This paper reports on the in vitro evaluation of bone like HA nanopowders. The prepared HA nanopowder was characterized for its phase purity, chemical homogeneity and bioactivity. Fourier transform infrared (FT-IR) spectroscopy was used to identify the functional groups. X-ray diffraction analysis was carried out to study the phase composition. The in vitro test was performed in a stimulated body fluid medium. The changes in the pH of SBF medium were measured at predetermined time intervals using a pH meter. The dissolution of calcium ions in the SBF medium was determined by an atomic absorption spectrometer. FT-IR spectroscopy result combined with the X-ray diffraction exhibited single phase of HA with carbonate peaks in the FT-IR spectrum. Results indicated that increasing the sintering temperature increases the crystallinity and the crystallite size of HA nanopowders. HA nanopowders ionic dissolution rate was found to be quite higher than conventional HA and closer to biological apatite owing to its nanostructure dimensions.