Multiple incorporation of copper and iron ions into the channel of hydroxyapatite

Abstract

As a way of tuning the composition of hydroxyapatite (Ca10(PO4)6(OH)2), metal ion incorporation into the hexagonal channel has been studied less than conventional isomorphous substitutions. In the present study, we successfully incorporated multiple metal ions into the hexagonal channel of hydroxyapatite by loading an aqueous solution containing Cu and Fe and subsequent heat treatment. The incorporation of multiple metal ions was confirmed by infrared spectroscopy, Raman spectroscopy and X-ray diffraction analysis combined with the Rietveld refinement. The composition of synthesized hydroxyapatite with the maximum content of multiple metal ions in the channel was Ca10(PO4)6Cu0.3Fe0.3OzHa. The location of Cu in the channel was revealed to be not affected by Fe in the channel and vice versa. In addition, deposition of the metal ions from the channel by heat treatment was examined for possible decoration of the hydroxyapatite by double-oxide nanoparticles.