Using a 36Cl radioactive label, we study the behavior of chloride ions during the adsorption interaction of hydroxyapatite (HA) with an aqueous solution of magnesium chloride at high concentrations. The kinetics of transfer of the label from the solution to the solid phase is investigated by liquid scintillation spectrometry, and the boundary concentrations of magnesium chloride at which this effect manifests itself are determined. At a concentration of the chloride ions above 0.6 mol/L, a topochemical reaction may occur with the incorporation of Cl– into the hydroxyapatite structure and the formation of an extraneous phase (whitlockite) or mixed Ca–Mg apatites with the partial replacement of OH by Cl.

We have studied Mg2+ adsorption on hydroxyapatite (HAp) nanocrystals and constructed its isotherm at equilibrium cation concentrations in the range 0–0.35 mol/L. For a number of samples, corresponding to characteristic points in the adsorption isotherm, the composition and the oxidation state of the elements present on the surface of the sorbent have been determined by X-ray photoelectron spectroscopy (XPS). The surface magnesium concentration determined by XPS, which detects only ions in a surface layer a few nanometers in thickness, has been found to be considerably lower than the total amount of cations in the solid phase, evaluated from the experimentally determined adsorption isotherm. We assume that, during the sorption process, some of the magnesium ions substitute for calcium ions in the bulk of the HAp and some adsorb in the form of MgCl2. The results obtained in this study constitute a fundamental basis for practical solutions in designing integrated medications based on HAp with magnesium.

Characteristic features of the sorption interaction of magnesium(II) ions in aqueous solutions with hydroxyapatite nanoparticles used as the sorbent were elucidated. The process kinetics was found to be adequately described by a pseudo-second order model. The sorption isotherm reflects consecutive changes in the mechanisms of sorbate and sorbent interaction with increasing sorbent concentration. Two main regions in the sorption isotherm were identified. Ion exchange is the major mechanism in the first region, while in the second region it is supplemented by physical adsorption. Formally, each region can separately be described by the Langmuir model with the following parameters: adsorption coefficient K = 33.7 and 32.1 L/mol and maximum adsorption Г∞ = 2.2 and 8.5 mol Mg/mol hydroxyapatite for the first and second regions, respectively. At high Mg2+ concentrations, morphological and structural changes of the sorbent were detected, which may be attributable to a chemical reaction between the components giving a new phase.

The size control of materials is of great importance in research and technology because materials of different size and shape have different properties and applications. This paper focuses on the synthesis of hydroxyapatite in ultrasound fields of different frequencies and intensities with the aim to find the conditions which allow control of the particles size. The results are evaluated by X-ray diffraction, Transmission Electron Microscopy, morphological and sedimentation analyses. It is shown that the hydroxyapatite particles synthesized at low intensity non-cavitation regime of ultrasound have smaller size than those prepared at high intensity cavitation regime. The explanation of observed results is based on the idea of formation of vortices at the interface between phosphoric acid and calcium hydroxide solution where the nucleation of hydroxyapatite particles is taken place. Smaller vortices formed at high frequency non-cavitation ultrasound regime provide smaller nucleation sites and smaller resulting particles, compared to vortices and particles obtained without ultrasound. Discovered method has a potential of industrial application of ultrasound for the controlled synthesis of nanoparticles.

A kinetic model for the precipitation of a dispersed compound from solutions is formulated, based on a description of the evolution in the function of its particle distribution according to its states during precipitation. A boundary problem about the precipitation of a compound during the evaporation of a solvent from a solution under conditions in which the rate of aggregate formation is high is considered. The solution to this boundary problem can be used to describe the formation of a film of polystyrene during the evaporation of its solution in toluene and o-xylene deposited onto a substrate.

The problem of the formation of a microrelief on the surfaces of polymeric bodies has been considered. The basis for a mesokinetic model of the formation of macromolecules, their aggregates, and polymeric bodies in a device filled with a monomeric solution has been reported. An equation for changes in the function of the distribution of structural elements of the body microrelief over states in the process of its formation is formulated. Experimental data have been reported on the microrelief of polymeric bodies that confirm the prevalence of morphological memory phenomena among polymers and can be used to create new materials.

Sonodynamic therapy in combination with antitumor drugs and sonosensitizers (theraphthal and its derivatives) was studied in preclinical testing against malignant tumors. The use of this therapy scheme enhances the destructive effect of ultrasound on tumors, promotes no metastasis, and make therapeutic drugs more bioavailable. The scheme was recommended for clinical use. A solid-phase sonosensitization mechanism was proposed. A possible system of laboratory and in vitro testing for selection of efficient sonosensitizers was outlined.

Morphological features of the formation of nanodisperse hydroxyapatite (HA) in the presence of different concentrations of collagen have been revealed by means of optical and electron microscopy. The possibility of nanoHA morphological modification with the formation of crystals whose geometric characteristics are close to those of native HA crystals has been shown. It has been examined how HA aggregates and forms together with collagen different hierarchical textures. By varying the collagen concentration, it is possible to control physical-chemical and mechanical properties of such textures. This makes them promising materials for medical applications. Structural studies performed by X-ray phase analysis and NMR spectroscopy have shown that though the phase composition of the obtained samples does not change, a chemical bond is formed between collagen and hydroxyapatite with further formation of an organo-mineral complex.

Morphological features of the formation of nanodisperse hydroxyapatite (HA) in the presence of different concentrations of collagen have been revealed by means of optical and electron microscopy. The possibility of nanoHA morphological modification with the formation of crystals whose geometric characteristics are close to those of native HA crystals has been shown. It has been examined how HA aggregates and forms together with collagen different hierarchical textures. By varying the collagen concentration, it is possible to control physical-chemical and mechanical properties of such textures. This makes them promising materials for medical applications. Structural studies performed by X-ray phase analysis and NMR spectroscopy have shown that though the phase composition of the obtained samples does not change, a chemical bond is formed between collagen and hydroxyapatite with further formation of an organo-mineral complex.

The work analyzes the possibility of treating the production of a functional material as the realization of the stage of separation of the substance forming the material from a supersaturated medium and the stages of physical and chemical modification of the separated substance. The key kinetic equation of variation of the distribution function of states of the particles of the substance at each stage is formulated, considering the discrete nature of the nucleation, growth, and aggregation of particles. Solutions to continuous versions of the kinetic equation with regard to each stage are given. The conception of the path \(\vec Z(\vec g)\) of obtaining the material is introduced in the form of the coupling function of the target properties \(\vec Z\) of the compound with characteristics \(\vec g\)} of the reactors where the material is produced. The conditions are considered under which the path can be regarded as optimal at each stage, and the optimality criteria of the routes are introduced.

Specific features of sorption of sodium [ 3 H]succinate on nanohydroxyapatite (HAP) and its hierarchic textures were studied by radionuclide-microscopic diagnostics. Chemisorption of sodium succinate leads to structural-morphological modification of HAP, manifested, in particular, in changes in the habit of individual nanocrystals and in the internal texture of HAP macrospheroids. The dynamics of sorption penetration of sodium succinate into macrospherical HAP granules was monitored by autoradiogarphy. The results obtained suggest that nanohydroxyapatite and textured products based on it can be used for the development of materials for drug transport and of complex succinic acid containing preparations for medical purpose.

It was shown by electron microscopy and X-ray diffraction that a polystyrene solid with a three-level hierarchical structure was formed when the solvent was evaporated from a solution of polystyrene in o -xylene (polystyrene molecules stuck together united to form a framework). The kinetics of the transformation of formerly dissolved molecules into aggregates could be described by a Fokker-Planck-type equation. Fullerenes introduced into a solution of polystyrene in amounts less than 0.1 wt % transformed aggregated polystyrene molecules into nanocrystals and accelerated the formation of aggregates. The influence of fullerenes on the kinetics of the processes could be correctly described in the continuum approximation taking into account aggregation rate fluctuations.