Composite materials based on gels and hydroxyapatite could provide promising characteristics for biomedical materials because of biocompatibility, osteointegration, and easy implementation. In this research, enzymatic synthesis of hydroxyapatite was studied as a technique for tissue engineering and scaffolds creation. The hydroxyapatite crystals were synthesized using this method and characterized with X-ray diffraction, electron microscopy, IR and Raman spectroscopy and analytical methods. As a result, a material with assumed composition of Ca10−x(HPO4)x(PO4)6−x(OH)2−x/CaHPO4/CaCO3 was obtained by enzymatic synthesis. The dynamics of size evolution, texture and crystallinity of the solid phase as a function of deposition time were also investigated. Afterwards, this method was used for gel mineralization with hydrogels such as agarose, alginate, gelatin, and polyacrylamide. Hydroxyapatite crystals obtained inside and above the hydrogels were analyzed with X-ray diffraction and electron microscopy. The particle diameter distribution functions were used to evaluate the mineralization in different gels. The shape and size of mineral inclusions depend on the density of the hydrogel grid. The localization of the formed solid phase depends on the nature of the gel and the concentration of alkaline phosphatase inside it. The results provide an opportunity to control the morphology of calcium phosphate particles produced during mineralization, which is important for the creation of biomedical materials with specified and reproducible characteristics.

The parameters of the sorption of yttrium ions on hydroxyapatite samples of various textural organization, viz. , lamellar nanoparticles (HAP n ) and porous microparticles synthesized by the enzymatic method (HAP e ), were studied. The values of the maximum amount adsorbed are shown to be higher in the case of HAP e , while the sorption process is faster in the case of HAP n . The sorption kinetics is well described by a pseudo-second-order model. The kinetics of isotope exchange between sorbed and dissolved yttrium was studied by the method of radioactive indicators using the 90 Y label. The exchange proceeds in several stages, at the first of which the available yttrium is exchanged from the sorbent surface. In the case of HAP e , a slow stage of yttrium exchange is observed apparently related to the yttrium located in the pore space of microparticles.

The use of hydroxyapatite obtained by enzymatic synthesis (HAPE) as a carrier of radionuclides (yttrium-90, copper(II) as a prototype of 64Cu and 67Cu and ruthenium-103 as a prototype of 97Ru) is considered. The processes of sorption and desorption of ions in different solutions are compared. The sorption of copper and yttrium on HAPE is almost irreversible, in contrast to the sorption of ruthenium, for which the reverse process depends on the medium.

A new peptidomimetic conjugate of natural methionine and pyridine-2,6-dicarboxylate was synthesized and evaluated as a potential ligand for 97Ru radiopharmaceuticals. The distribution of this radiopharmaceutical in mice was investigated. A fundamental difference was found in the distribution and excretion of ruthenium complex and free ruthenium ion in the body, which suggests a difference in their transport pathways due to the stability of the complex in the body.

Modification of the cocrystallization method for producing hydroxyapatite (HAP) and an HAP-Cu combination to the enzymatic method using alkaline phosphatase leads to a change in the morphology, sizes, sorption capacity, type of particles, and conformity with the Langmuir and Freundlich models. A positive factor of the enzyme usage is an increase in the sorption capacity and the possibility to strictly control the particle sizes depending on the concentration of the enzyme used. The L 2 CuCl 4 complex was synthesized on the basis of 2-aminopyrimidine (L), which is the precursor of many anticancer drugs, and the possibilities of introducing L 2 CuCl 4 into the HAP composite were considered. The cytotoxicity data for various HAP and L 2 CuCl 4 composites with respect to various types of leukemic cells as compared to lymphocytes of healthy donors showed antileukemic activity of the copper complex and the absence of HAP cytotoxicity in a wide range of concentrations.