Preparation of Copper-Doped Hydroxyapatite with Varying x in the Composition Ca10(PO4)6CuxOyHz

The pro-angiogenic potential of copper ions could increase the viability of bone forming cells within a bone substitute scaffold, and so hasten healing, by stimulating infiltration of blood vessels into the scaffold. Copper-doped hydroxyapatite with x = 0, 0.5, 0.75 and 1 in the nominal formula Ca10(PO4)6CuxOyHz was prepared by solid state synthesis. Lattice parameters increased as x was increased, consistent with formation of Cu-O species on hydroxyl sites. In FT-IR spectra, the OH stretch (3572 cm-1) and the OH libration (631 cm-1) decreased in intensity as x was increased, and a band at 771-778 cm-1 was assignable to a Cu-O stretch, characteristic of Cu+ bands between 3140 and 3450 cm-1 related to copper-disturbed OH stretching vibrations. In UV visible spectra, bands between 400 and 800 nm were assignable to d-d transitions of Cu2+. Therefore we propose that Cu is present in these materials both as Cu+ and Cu2+.