Synthesis, characterization and in vitro studies of zinc and carbonate co-substituted nano-hydroxyapatite for biomedical applications

Ionic substitutions have been proposed as a tool to improve the properties of hydroxyapatite (HA). Zinc and carbonate co-substituted HA have been synthesized by precipitation method and characterized by XRD, FT-IR, XRF, FESEM and TEM. Comparative studies were carried out with HA, zinc substituted HA and carbonate substituted HA. Zinc substituted HA exhibited less dissolution and apatite forming ability but more decomposition into TCP at 1400 °C when compared with carbonate substituted HA. When zinc is co-substituted with carbonate it exerted a control over the apatite forming ability of HA which was found to lie in between the individual substituted samples without compromising the dissolution behavior of CHA. Also, decomposition was reduced to a greater extent. Hence tailoring the properties of HA to the desired extent can be achieved by simultaneous substitution of zinc and carbonate.

► Co-substitution of Zn reduced the crystallite size of CO32− substituted HA further. ► Co-substitution of Zn regulated the apatite forming ability of CO32− substituted HA. ► Thermal stability of Zn-HA was increased when carbonate was co-substituted.