Synthesis, crystal structure and biological activity of bismuth-sodium-oxoapatite

Abstract

In this work, a comprehensive physicochemical analysis of a promising bismuth-sodium-oxoapatite obtained by solid-state method was conducted using X-ray and spectroscopic methods. The true composition of the compound can be described by the formula Ca7.8BiNa0.8(PO4)5.4O1.6, with the non-stoichiometry attributed to the formation of secondary phases that are absent in the final substance due to their melting during the synthesis. The refinement of the crystal structure showed that sodium ions are located in the 4f position, while bismuth ions occupy the 6h position. An IR spectroscopic analysis provided independent confirmation of the compositional group of the substance under study, in particular, the absence of pyrophosphate and hydroxyl groups. A comprehensive study of the phase stability of the substance in water, phosphate buffer, and trypsin revealed no changes in the phase and elemental composition of the material for up to 24 h. The standard MTT test demonstrated the absence of cytotoxicity of the compound. In experiments with S. aureus and E. coli cultures, the apatite under investigation did not exhibit any antibacterial activity.