Co-doping of hydroxyapatite with zinc and fluoride improves mechanical and biological properties of hydroxyapatite

Hydroxyapatite (HA) co-doped with Zn 2+ and F − ions was synthesized by precipitation method for the first time in this study. FTIR spectroscopy revealed Zn 2+ and F − ions incorporation into HA structure. Co-doping of Zn 2+ and F − ions decreased unit cell volume of HA and decreased grain sizes. Zn 2+ or 5 mol% F − addition into HA significantly improved its density. Microhardness was increased with Zn 2+ addition and further increase was detected with F − co-doping. Zn 2+ and F − co-doped samples had higher fracture toughness than pure HA. Zn 2+ incorporation to the structure resulted in an increase in cell proliferation and ALP activity of cells, and further increase was observed with 1 mol% F − addition. With superior mechanical properties and biological response 2Zn1F is a good candidate for biomedical applications.