Mechanochemical Synthesis and Biological Properties of Bi-Substituted Hydroxyapatite

The mechanochemical synthesis and study of the structure of hydroxyapatite compounds with the substitution of calcium(II) cation for bismuth(III) cation has been carried out. Bismuth oxide and bismuth nitrate pentahydrate were used as a source of bismuth. It has been shown for the first time that, when using bismuth nitrate, the synthesis product contains a nitrate group, resulting in a multiphase system, whereas when using bismuth oxide, a monophase material with an apatite structure is synthesized, where the degree of substitution of calcium by bismuth can be increased up to 40 mol %. A chemical formula for the obtained substitution series is proposed. It was found that, at low concentrations of bismuth, the material stimulates the proliferation of osteoblast-like MG-63 cells; therefore, it is recommended for use in bone tissue regeneration.