Mesoporous Iron(III)-Doped Hydroxyapatite Nanopowders Obtained via Iron Oxalate.

Mesoporous hydroxyapatite (HA) and iron(III)-doped HA (Fe-HA) are attractive materials for biomedical, catalytic, and environmental applications. In the present study, the nanopowders of HA and Fe-HA with a specific surface area up to 194.5 m ² /g were synthesized by a simple precipitation route using iron oxalate as a source of Fe ³⁺ cations. The influence of Fe ³⁺ amount on the phase composition, powders morphology, Brunauer-Emmett-Teller (BET) specific surface area (S), and pore size distribution were investigated, as well as electron paramagnetic resonance and Mössbauer spectroscopy analysis were performed. According to obtained data, the Fe ³⁺ ions were incorporated in the HA lattice, and also amorphous Fe oxides were formed contributed to the gradual increase in the S and pore volume of the powders. The Density Functional Theory calculations supported these findings and revealed Fe ³⁺ inclusion in the crystalline region with the hybridization among Fe-3d and O-2p orbitals and a partly covalent bond formation, whilst the inclusion of Fe oxides assumed crystallinity damage and rather occurred in amorphous regions of HA nanomaterial. In vitro tests based on the MG-63 cell line demonstrated that the introduction of Fe ³⁺ does not cause cytotoxicity and led to the enhanced cytocompatibility of HA.