Sodium polystyrene sulfonate template assisted hydrothermal synthesis of hydroxyapatite nanorods

Abstract

Hydroxyapatite nanoparticles (nHAp) have been synthesized by benign hydrothermal reaction from the aqueous mixture of Ca(NO₃)₂·4H₂O and (NH₄)₂HPO₄ solutions in the presence of non-toxic sodium polystyrene sulfonate (PSS) template. The <i>p</i>H of starting precursors has been adjusted to 10.5 before hydrothermal treatment at 100°C for 1, 2 and 3 h. The added PSS template generates the largely negative surface of dicalcium phosphate dihydrate (DCPD) precursor, resulting in minimization of precursor agglomeration and promoting the hydrothermal growth of nHAp along preferential <i>c</i>-axis as rod-shaped crystals. The crystallite sizes along 002-plane of nHAp synthesized with and without PSS template are 47.1 and 29.5 nm, respectively. With longer hydrothermal treatment time, larger crystallite size of nHAp is obtained. <i>In vitro</i> cytotoxicity of the synthesized nHAp has been evaluated by MTT assay using African green monkey kidney fibroblast cells, in which the nHAp exhibits low cytotoxicity. Antibacterial activities of the synthesized nHAp against <i>S.aureus</i> and <i>E.coli</i> have been tested. Due to the presence of largely negative surface, the nHAp could inhibit only the gram-positive<i> S.aureus</i>, creating a clear zone of about 9.5 mm.