Synthesis and characterization of niobium-doped fish scale-derived hydroxyapatite by physical ultrasound interference

Fish scales of the Arapaima gigas (pirarucu) species were heat-treated to obtain natural hydroxyapatite (HAp), and it was doped with niobium (Nb) by physical ultrasound interference to confirm an effective route to the production of Nb-doped HAp powders. The effect of ultrasound application on doping was investigated. The structure of the powders was elucidated using X-ray diffractometry (XRD), scanning electron microscopy, IR spectroscopy, and X-ray fluorescence spectroscopy (XRF). XRD results of Nb-doped HAp powders were compared with undoped natural hydroxyapatite and ICSD-26204 standard as controls. The crystallinity of Nb-doped HAp powders increased from 39% to 51% after the ultrasound application. IR spectroscopy confirmed hydroxyl, carbonate, and phosphate functional groups in the sample. Results obtained by XRF confirmed the ionic substitution of Ca for Nb with an average content of 1%. Therefore, the effectiveness of the synthesis route was confirmed to produce hydroxyapatite-niobium crystalline powder with physicochemical integrity as a potential biomaterial for bone implant application. (author)