Fe³⁺ /SeO42^- dual doped nano hydroxyapatite: A novel material for biomedical applications

Dual ions substituted hydroxyapatite (HA) received attention from scientists and researchers in the biomedical field owing to their excellent biological properties. This paper presents a novel biomaterial, which holds potential for bone tissue applications. Herein, we have successfully incorporated ferric (Fe³⁺ )/selenate ( SeO42-) ions into the HA structure (Ca_10-x-y Fe_y (PO₄ )_6-x (SeO₄ )_x (OH)_2-x-y O_y ) (Fe-SeHA) through a microwave refluxing process. The Fe-SeHA materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FESEM). XRD and FTIR analyses revealed that Fe-SeHA samples were phase pure at 900°C. FESEM images showed that formation of rod-like shaped particles was inhibited dramatically with increasing Fe³⁺ amount. The Vickers hardness (HV) test showed that hardness values increased with increasing Fe³⁺ concentrations. Optical spectra of Fe-SeHA materials contained broadband over (200-600) nm. In vitro degradation and bioactivity tests were conducted in simulated body fluid (SBF). The incorporation of Fe³⁺ / SeO42- ions into the HA structure resulted in a remarkably higher degradation rate along with intense growth of apatite granules on the surface of the Fe-SeHA discs with Ca/P ratio of 1.35-1.47. In vitro protein adsorption assay was conducted in fetal bovine serum (FBS) and it was observed that the adsorption of serum proteins on Fe-SeHA samples significantly increased with increasing Fe³⁺ concentration. In vitro cytotoxicity tests were performed with human fetal osteoblast (hFOB) cell line and the results demonstrated that hFOB cells attached and proliferated faster on the Fe-SeHA materials compared to pure HA showing that Fe-SeHA materials were cytocompatible. ALP activity and intracellular calcium of hFOB cells on 1Fe-SeHA discs were statistically higher than pure HA, suggesting that presence of Fe³⁺ ion supported osteogenic differentiation of hFOB cells. Our results suggest that 1Fe-SeHA (0.2M Fe³⁺ /0.5M SeO42- co-doped HA) material could be considered as a promising candidate material for orthopedic applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 340-352, 2018.