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Interaction between the systems containing cobalt(II) or nickel(II) chlorides and 2-thiobarbituric acid (C4H4N2O2S, H2L) was examined by spectrophotometry and pH-metry at pH < 4, I = 0.1 (NaCl) and T = 20°C. The compositions and the overall stability constants (log β11) of protonated complex species were determined: [CoHL]+ (3.69 ± 0.04), [NiHL]+ (3.68 ± 0.08), and [M(HL)2]. The compositions of the Co(C4H3N2O2S)2 · 4H2O and Ni(C4H3N2O2S)2 · 5H2O salts isolated from the studied systems were confirmed by different physicochemical methods; their solubility constants (log KS) were calculated to be –12.82 ± 0.22 and –12.30 ± 0.10, respectively. A spectrophotometric technique was developed for determining thiobarbiturate ion in aqueous solutions. This technique is based on the absorbance of iron(III) thiobarbiturate complex [FeL]+ and can be recommended for analytical chemists and pharmacists.

Hydroxyapatites modified with metal ions are the main inorganic components of bone tissue and are approved for use as components for biocomposites and coatings for surgical implants. This study examined prototypes of functional materials for bone implants based on hydroxyapatite modified with zinc ions. Zinc-modified hydroxyapatite was composed and synthesized. Using the XRD method, the phase composition was established. Using SEM, EPMA, and low-temperature nitrogen adsorption (BET) methods, surface properties were investigated. Antibacterial activity and biocompatibility have been established. The studied materials have antimicrobial activity, the samples did not cause significant changes in either the internal organs or the general condition of laboratory animals during the entire experiment.

The phase composition and unit cell parameters were determined for composites based on polylactide and hydroxyapatite with the polylactide/hydroxyapatite weight ratios of 90/10, 80/20, 70/30, and 60/40. As the polylactide content of the composites is increased, they become less hydrophilic, and the surface energy σS-G increases from 29.13 to 74.35 mJ m–2. The sample with the component weight ratio of 70/30 is characterized by the maximal roughness, and the Ca2+ and Mg2+ ions from simulated body fluid are actively adsorbed onto its surface, as proved by SEM examination of the composites.

Relevance of the work is due to the need for new materials that are used in medicine as a substitute for natural bone tissue injuries, fractures, etc. The aim of the work is to obtain composites with improved biocompatible properties based on poly-L-lactide (PLA) and hydroxyapatite (HA) and to perform pilot analysis of interaction PLA, HA, composite PLA-HA with primary human monocytes-derived macrophages in vitro. The pilot experiments using human primary monocytes cultivated on the surface of the samples demonstrated that PLA-HA can stimulate release of anti-inflammatory cytokines that indicates the presence of potential anti-inflammatory properties of the composites

Composites based on lactic acid oligomers, calcium hydrophosphate and hydroxyapatite synthesized under the action of microwave radiation were obtained in situ. The appearance of a new band associated with stretching vibrations of >C=O in spectra of the chloroform-insoluble fraction is indicative of the chemical interaction between lactic acid and hydroxyapatite. To determine whether a calcium phosphate layer can be formed on the surface of composite samples, biomimetic studies in a physiological SBF solution were carried out during 28 days at 37°C. It was found that all samples containing calcium phosphates promote active formation of a new calcium phosphate layer, whereas lactic acid oligomer in samples containing no inorganic component undergoes destruction in the SBF solution as a result of hydrolysis. The estimate of the resorption rate demonstrated that the solubility of calcium phosphates contained in the composites at 20°C in the physiological solution is 3–7 times that of pure hydroxyapatite.

Composite materials for the restoration of bone tissues based on hydroxyapatite and a copolymer of lactide and glycolide were obtained. The composition of materials at different stages of production is estimated by X-Ray diffraction method. It has been established that during the production of materials a new phase of chlorine-substituted hydroxyapatite (Ca9.7(P6O23.81)Cl2.35(OH)2.01) was formed, which promoted an increase of hydroxyapatite solubility in the composition of materials. The quantitative estimation of micro- and macroporosity of materials is given. It was found that the use of sodium chloride as the pore-forming agent delivers porosity of the composites required for use as bone substitutes.

The samples of silica-modified hydroxyapatite (SHA) with various contents of silicate ions have been synthesized via liquid-phase precipitation with the use of microwave radiation. The composition of obtained solid-phase products has been determined according to X-ray phase analysis and IR spectroscopy. The micromorphologies of SHA powders and their water solubility have been studied at pH 7 and 20°C.

The authors obtained two-phase samples of silver- and zinc-modified hydroxyapatite (AgHA, ZnHA) by liquid-phase deposition under microwave exposure; the main phase for all samples was hydroxyapatite Ca5(PO4)3(OH) with hexagonal syngony. The parameters of the elementary lattice of HA were studied via X-ray phase analysis and confirmed the formation of solid substitutional solutions while modifying HA with silver and zinc ions. Solubility has been estimated at 20 ºC for a 0.9% NaCl solution; specific surface area and porosity have been estimated for ZnHA powders obtained in presence of aminoacids. Surface morphology and dispersiveness have been studied for AgHA and ZnHA powders. Hammett method helped to establish the presence of acidic and basic centers on the surface of ZnHA and AgHA. Koch biotesting showed HA, AgHA, and ZnHA acting as inhibitors thus affecting E. coli tested samples. HA, AgHA, and ZnHA powders can be recommended for medical purposes.

Method for microwave liquid-phase synthesis of hydroxyapatite samples was developed. The composition of the synthesis products obtained and natural hydroxyapatite was studied by X-ray phase and X-ray fluorescence microanalysis. IR spectra were measured and the dispersity of hydroxyapatite powders obtained, their solubility in water at 20°C, and structural parameters were determined in comparison with natural hydroxyapatite and that produced by the common (“classical”) liquid-phase technique. The microwave-synthesized hydroxyapatite compares well in its properties with the biological and “classical” hydroxyapatites.

The stability constants of 1: 1 and 1: 2 acidic copper(II) violurate complexes and the CuL complex, where L is the anion of violuric acid (H2L), were determined by pH-metry at ionic strength I = 0.1 at 20°C. The stability of the violurate complexes of triply charged cations [ML]+ and quadruply charged thorium [ThL]2+ increases in the sequence La3+, Gd3+, Y3+, Sc3+, Th4+, Fe3+. It was shown that violuric acid behaves as either mono- or dibasic, depending on the conditions, with respect to all of these cations.

The effect of silver adding to hydroxyapatite (HA) in its solubility in physiological solution and biological activity was investigated. Samples of HA containing silver (AgHA) obtained by liquid-phase method in the conditions of microwave exposure. Solubility (CCa2+·103, mol/l) of the powders AgHA was determined by chemical methods according trilonometric titration of the calcium ions in physiological solution at 25 and 37 °C. To investigate the biological activity of the samples, a series of experiments on the formation of the calcium-phosphate layer on the surface of the SBF-solution at 37 °C for 28 days. Electronic micrographs of samples taken at the end of each 7 days of the experiment, indicate the formation of calcium-phosphate layer (CPL) in the samples, the kinetics of which is shown as a function of cumulative concentrations of calcium and magnesium ions from time.

A new methodin situfor producing of biocompatible composites based on hydroxyapatite and oligomers of lactic and glycolic acid is described. Their thermo-mechanical, physical-chemical and biological properties are studied as well. The formation of bonds between hydroxyapatite with lactic and glycolic oligomers in composites are confirmed by IR spectroscopy of the samples, including those obtained in the Soxhlet apparatus. The formation of calcium-phosphate layer on the composite's surface containing hydroxyapatite was shown by SBF-investigation. The scaffolds based on lactic acid oligomer do not stimulate formation of a calcium-phosphate layer and they are subjected to destruction by the way of hydrolysis.