Features of physicochemical properties of the hydroxyapatite—ruthenium system depending on the stage of metal ion introduction into the cocrystallization process

The influence of small amounts of ruthenium(iii) ions on the morphology, phase composition, and structure of the products formed under the conditions of hydroxyapatite (HAP) synthesis was studied by electron microscopy (including high resolution), energy dispersive analysis, and XRD. The introduction of doping ruthenium(iii) ions into the reaction medium at various stages of HAP formation affects the degree of aggregation of primary HAP—Ru nanoparticles. In the case of introducing Ru at the final stage of HAP synthesis, the formation of individual thread-like HAP—Ru nanoparticles is observed, but no formation of the intrinsic ruthenium phase is observed. The Ru^III ions are distributed predominantly uniformly over the nanoparticle surface. The cocrystallization method for preparing composites of HAP with ruthenium radionuclides is promising for the development of new radiopharmaceuticals.