Biogenic hydroxyapatite (BHA) is a promising material of natural origin for bone tissue replacement due to its good biocompatibility and close similarity to the mineral component of bone. The combination of hydroxyapatite with bioactive glass enhances both its bioactivity and mechanical properties. Carbon fibers (CFs), which are nanostructured materials prepared from hydrated cellulose fiber cloth, also have a natural origin and can be used in biomedical applications. This study investigates the structure, physicochemical properties, immersion behavior, and cytotoxicity of BHA/glass/CFs composites containing 10, 30, and 50 wt% activated CFs, prepared by closed sintering at 800 degrees C. The phase composition was analyzed using X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR), indicating the preservation of CFs in the composite structures. As the CFs content increases, the fibrous phase becomes more dominant, forming an interconnected network that contributes to the development of a hierarchical porous structure. Microstructural studies also confirmed the presence of CFs in the composite structures. The composite skeleton density ranges from 2.44 to 2.83 g/cm3 and decreases with increasing CFs content. Immersion tests in saline demonstrated that higher CFs content leads to increased pH variation and solubility, attributed to the significant increase in the specific surface area. Postimmersion characterization of the composites after immersion in saline was examined to simulate their interaction with biological media, including XRD and microstructural analysis, was performed to simulate their interaction with biological media and confirmed the stability of the phase composition. Cytotoxicity evaluation using the MTT assay with MDCK and MDBK cell lines revealed no toxic effects for any of the compositions.

The development of effective non-invasive surgical materials for treating bone tissue injuries and diseases remains a pressing issue, necessitating the search for novel biomaterials. In this study, new injectable hydrogel composites based on sodium alginate with different types of calcium phosphates were synthesized via crosslinking and characterized. Three different calcium phosphate (CaPs) powders, as synthetic hydroxyapatite (SHA), biogenic hydroxyapatite (BHA), and J3-tricalcium phosphate (J3-TCP), were prepared and used as starting materials for composite hydrogels. Sodium alginate hydrogel (AlgNa hydrogel) was prepared at 2 wt% concentration as the starting material. The prepared hydrogel composites contained calcium phosphate phases at concentrations of 1, 2, and 3 wt% in a constant AlgNa hydrogel matrix. X-ray studies showed the preservation of the phase composition of calcium phosphate materials in the composite structure. Fourier transform infrared spectroscopy also confirmed the presence of functional groups of AlgNa and CaPs in the composite structure. The microstructure of prepared composites was investigated. Skeleton density, injectability, adsorption activity and swelling behavior of the composites were analyzed. An injectability study (the force to initiate extrusion and the force to sustain the extrusion) was conducted, which is necessary when using hydrogels as injectable materials. The adsorption activity of the composites was examined using methylene blue as a model compound. The cytotoxicity of the composites, as assessed by the MTT method, depended on the type of CPs, as well as the eluate concentration. The results demonstrated a significant structural and property variation depending on the type of calcium phosphate used.

A biomimetic composite based on biogenic hydroxyapatite (BHA) and chitosan (CS) with a weight ratio of 70:30, corresponding to the mineral-to-organic ratio of native bone tissue, was successfully prepared in injectable and scaffold forms. The phase composition, microstructure, specific surface area, skeleton density, rheological behavior, injectability, suspension stability, resorption behavior, and cytocompatibility of the composite were investigated. Structural characterization by XRD, FTIR, and SEM confirmed the preservation of the crystalline hydroxyapatite phase, the absence of secondary phases, and a homogeneous distribution of BHA particles within the chitosan matrix. Rheological studies revealed non-Newtonian shear-thinning behavior with an apparent yield stress of ~250 Pa and a multistage hysteretic flow response associated with shear-induced structural rearrangements within the CS–BHA network. Following shear cessation, the viscosity recovered to approximately 80% of its initial value, confirming satisfactory injectability and suitability for minimally invasive administration. Turbiscan analysis demonstrated good physical stability of the injectable suspension and improved stability after 30 days of storage. The material exhibited controlled resorption in physiological saline while maintaining its structural integrity. Cytotoxicity studies demonstrated satisfactory cytocompatibility, with the observed biological response being concentration-dependent. Overall, the developed BHA/CS composite combines structural stability, controlled resorption, favorable rheological properties, injectability, suspension stability, and cytocompatibility, making it a promising biomimetic material for bone tissue regeneration applications.

Two types of hydroxyapatite powders different origin (biogenic and synthetic) were coated by graphene oxide using LPCVD method and studied by SEM, XRD, FTIR, BET and DLS. Biogenic and synthetic hydroxyapatites remained phase-pure after LPCVD modification, showing no secondary phases formation. The adsorption capacity for methylene blue increased by 50% for coated hydroxyapatites, despite the thinness of the layer and the decrease in specific surface area of powders. Moreover, graphene oxide allows to keep moderately negative zeta potential of both modified hydroxyapatites during 6 months in comparison to pure powders that could promising influence on bone regeneration.

Alginate-based injectable hydrogels have held the attention of researchers due to their significant biomedical potential and unique properties. In this study, Si-modified biogenic hydroxyapatite/alginate hydrogel composites (AlgNa/Si-BHA) were prepared by ionic crosslinking with different amounts of the inorganic component (1%, 2% and 3%), which contain 2 and 5 wt.% silicon. The composites were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), differential thermogravimetric analysis (DTGA), scanning electron microscopy (SEM), helium pycnometry, and swelling behavior analysis. XRD and FTIR analyses confirmed the presence of AlgNa hydrogel and hydroxyapatite phases as well as silica bands. The DTGA results demonstrated that the presence of silicon in composites increases thermal stability at high temperatures. SEM imaging showed the formation of specific porous relief structures for all types of composites. SEM/EDS analysis confirms the presence of all main elements of the composite, such as calcium, phosphorus, oxygen, silicon, sodium, and carbon. For AlgNa/2Si-BHA and AlgNa/5Si-BHA composites with different ratios of components, the skeleton density was in the range of 1.14-1.66 g/cm3. Swelling studies demonstrated a significant effect of silicon on equilibrium swelling degree; namely, it is increasing for AlgNa/Si-BHA compared to AlgNa/BHA and allows obtaining composites with swelling higher by 30% in contrast to a pure hydrogel, which confirms the feasibility of creating this type of hydrogels.

Highly porous bioceramics (porosity equal to 93–94 %) based on biogenic hydroxyapatite and sodiumborosilicate glass (40wt% of glass) was prepared by foam replication method at 700 °C and coated by graphene oxide using CVD method. Obtained bioceramics samples were studied by SEM, XRD and Raman spectroscopy. Phase composition, morphology, skeleton density, porosity and compression strength were evaluated. It was shown that biogenic hydroxyapatite in highly-porous bioceramics composition is stable and keeps hydroxyapatite phase without secondary phase formation after sintering with sodiumborosilicate glass as well as after application of CVD method for graphene oxide coating. Formation of graphene oxide for coated bioceramics was confirmed by XRD, SEM and Raman spectroscopy. Significant effect of graphene oxide coating on the porosity and skeleton density was not detected due to thin layer and low content of graphene oxide, but it allows 30 % increasing the compression strength of highly porous bioceramics.

The work is devoted to the investigation of the long-term resorption of BHA/magnetite/chitosan composites with a magnetite content of 1, 5, 25, and 50 wt.% in physiological solution for different periods of time (2, 10, 16, and 31 days) and their adsorption activity toward methylene blue. It was shown that the content of magnetite significantly affects the rate of resorption of materials, in particular at the initial stages; the highest rate of resorption is observed during the first 2 days. In the next 8-10 days, a sharp decrease in the rate of resorption of all composites is observed, followed by stabilization on the 15th day of the in vitro experiment. At the same time, the most significant weight loss of test samples occurs when added more than 5 wt. % of magnetite. The dynamics of the dissolution process is also confirmed by the presence of Ca, P and Fe in physiological solution, a change in the pH of the saline, a decrease in the size and smoothing of composite particles, and an increase in the specific surface area. The adsorption activity for methylene blue increases with increasing amounts of chitosan and magnetite in the composites up to 168 mg/g for 25% magnetite (2.5% chitosan) compared to 108 mg/g for pure BHA. The obtained results confirmed the controlled resorption and high adsorption properties of BHA/magnetite/chitosan composites, which provides prospects for their medical application.

In this work, hydrogel composites based on sodium alginate (AlgNa) and biogenic hydroxyapatite (BHA) were obtained by physical crosslinking followed by lyophilization. BHA in amounts of 1, 2, 3 and 10 wt

In equine medicine, assisted bone regeneration, including use of biomaterial substitutes like hydroxyapatite (HAP), is crucial for addressing bone defects. To follow-up on the outcome of HAP-based bone defect treatment, the advancement in quantified diagnostic imaging protocols is needed. This study aimed to quantify and compare the radiological properties of the HAP graft and natural equine bone using Magnetic Resonance (MR) and Computed Tomography (CT), both Single (SECT) and Dual Energy (DECT). SECT and DECT, allow for the differentiation of three HAP grain sizes, by progressive increase in relative density (RD). SECT, DECT, and MR enable the differentiation between natural cortical bone and synthetic HAP graft by augmentation in Effective Z and material density (MD) in HAP/Water, Calcium/Water, and Water/Calcium reconstructions, alongside the reduction in T2 relaxation time. The proposed quantification provided valuable radiological insights into the composition of HAP grafts, which may be useful in follow-up bone defect treatment.

A comparative study of the structure and properties of composite materials produced from biogenic hydroxyapatite/glass/carbon fibers, depending on the type of carbon fibers (activated carbon nanostructured fibers or cellulose fibers), was conducted employing scanning electron microscopy, X-ray diffraction, infrared spectroscopy, Brunauer–Emmett–Teller method, helium pycnometry, and in vitro experiments. The potential to produce a biogenic hydroxyapatite/glass/carbon fiber composite by sintering at 800°C, involving the simultaneous formation of carbon nanostructures during thermal destruction and carbonization of cellulose fibers, was ascertained. This method allows preserving the hydroxyapatite phase in the newly formed biogenic hydroxyapatite/glass/carbon fiber composite and ensures the presence of carbon nanostructures. The microstructure of the composites produced with activated carbon nanostructured fibers is characterized by the presence of these fibers, contrastingly to the composite produced with cellulose fibers, which has more homogeneous microstructure. Moreover, as opposed to cellulose fibers, activated carbon nanostructured fibers in the composite significantly increase (by more than three times) the specific surface area of the material and significantly reduce the particle size. Regardless of the carbon fibers used, the biogenic hydroxyapatite/glass/carbon fiber composites are nanostructured and microporous (pores < 2 nm). The resorption rate of the biogenic hydroxyapatite/glass/carbon (activated nanostructured or hydrated cellulose) fiber composites in the physiological solution within the first two days is significantly higher than that of the starting biogenic hydroxyapatite/glass composites because of changes in the porous structure.

A comparative study of the morphology and physicochemical properties of magnetite synthesized by chemical precipitation for 5 min, 30 min, and 1 h and by thermolysis in nitrogen and hydrocarbon atmospheres was conducted. Regardless of the synthesis method, duration, and atmosphere, the powders were found to have spherical particles, uniform particle size distribution, and ability to agglomerate. The chemical precipitation method produced powders within a narrower size range, specifically up to 56 nm, in contrast to the thermolysis method, characterized by a particle size of up to 84 nm. Gravimetric analysis of the kinetic laws of water vapor adsorption on the synthesized powders in an air flow with a relative humidity ranging from 60 to 100

Today bone tissue engineering is one of the most used technologies for treat bones injure. Materials containing hydroxyapatite and graphene have received much attention recently. The aim of this study was preparation of biogenic hydroxyapatite bioceramics modified by graphene-like structures investigation effect of graphene on the structure and properties of material. Biogenic hydroxyapatite bioceramics modified by graphene-like structures were successfully prepared by chemical vapor deposition (CVD) method. Subsequently, microstructure, composition, specific surface area, skeleton density, resorption rate in physiological solution and cytotoxicity were evaluated. XRD, IR spectroscopy, micro-Raman spectroscopy and SEM proved graphene oxide’s formation on biogenic hydroxyapatite as well as on silica single crystal for comparison. Although the coating of graphene-like structures on biogenic hydroxyapatite bioceramics reduces the specific surface area, it allows to 4 times increase resorption rate of biogenic hydroxyapatite bioceramics in physiological solution and does not affect the overall assessment of the cytotoxicity. MTT assay established non-cytotoxic effect and indicated a high potential of biogenic hydroxyapatite bioceramics modified by graphene-like structures using CVD method for medical application.

The work is devoted to the investigation of the morphology and adsorption properties of powder composites based on biogenic hydroxyapatite modified by magnetite (1, 5, 25, 50 wt. %) of various types (synthesis methods) and chitosan. The morphology of the powders evaluated using SEM micrographs and AMIS software is characterized by a uniform distribution of particles size and shape. It was established that the use of magnetite synthesized by chemical precipitation in the amount of 1-5% allows to obtain composite materials with a particle size in a narrower size range. Analysis of the kinetics of adsorption-desorption processes showed that the adsorption of water vapor is directly related to the ratio of hydroxyapatite and magnetite, increasing with increasing magnetite content. In addition, it is shown that the adsorption process for composites modified by magnetite obtained by the chemical precipitation method proceeds uniformly, while for composites containing magnetite obtained by the thermal decomposition method, three consecutive stages of the adsorption process are characteristic: rapid linear increase in mass, gradual inhibition of the adsorption process and stabilization of the mass of the material. The evaluation of the increase in mass also indicates a connection with the ratio of hydroxyapatite and magnetite, increasing with increasing magnetite content, which confirms the presence of physicochemical processes of interaction of gas molecules with the active centers of the molecules of the studied materials. DTGA also shows that the type of magnetite in an amount of more than 25% significantly affects the mass loss of composites during heat treatment up to 1000 °C, which is related to the initial characteristics of the magnetite used. The presented results in combination with previously obtained physicomechanical and biochemical properties testify to the prospects of biogenic hydroxyapatite/magnetite/chitosan composite materials for medicine.

In the present work, a method of synthesis of biogenic hydroxyapatite-based composites modified by magnetite (1, 5, 25, 50 % by weight) and chitosan was developed. The composition and structure were studied by X-ray diffraction analysis (XRD), infrared (IR) spectroscopy and scanning electron microscopy (SEM). According to X-ray phase analysis, the particle size varies from 43.6 nm to 53.8 am for composites containing magnetite obtained by chemical precipitation and from 43.6 nm to 50.1 nm for composites containing magnetite obtained by thermal decomposition in a nitrogen environment. The investigation of morphology showed that composite materials, regardless of the ratio of BHA and magnetite and its type (method of production) are characterized by significant agglomeration of rounded particles.

This work is devoted to the investigation of interaction of BHA/magnetite/chitosan composites with a magnetite content of 1, 5, 25, and 50 wt.% with physiological solution and their cytotoxicity. It was established that increasing of magnetite content leads to increasing of composites resorption. Moreover, the use of magnetite obtained by chemical precipitation in amount of 5-50 % allows to achieve resorption rate equal to 2.55.3 wt.% /day,which in 3.5-7.5 times higher in comparison with "pure" biogenic hydroxyapatite and 1.2-2 times higher in comparison with composites with magnetite obtained by decomposition in nitrogen media. The process of resorption is also confirmed by change in pH,presence of Ca, P and Fe in physiological solution after experiments in vitro, decreasing of particles size and increasing of specific surface area of the composites powders. The results of cytotoxicity study confirmed that BHA/magnetite/chitosan composites have no cytotoxic effect. That is why prepared composites could be promising for use in medicine.

The phase composition and structure of biogenic hydroxyapatite/glass/carbon fiber composites were studied in the light of their potential medical applications. Calcium phosphate glass ceramics produced from biogenic hydroxyapatite and activated nanostructured carbon fibers were used as the starting materials. The starting glass ceramic, which is a bioactive material and can be used to replace defective parts of bone tissue, was prepared by sintering powder mixtures of biogenic hydroxyapatite and sodium borosilicate glass. The starting activated nanostructured carbon fiber material, which can be used as a drug delivery system due to its structure, surface morphology, and internal pore structure, was produced by controlled incremental pyrolysis of cellulose hydrate fibers. To prepare the composites, the activated nanostructured carbon fiber material was impregnated with glass-ceramic slurry, dried at up to 40°C, and incrementally heat-treated at 800°C. The phase composition of the prepared materials was monitored by X-ray diffraction (XRD) and IR spectroscopy. The structure was examined by scanning electron microscopy. According to XRD and IR spectroscopy, the prepared biogenic hydroxyapatite/glass/carbon fiber composite contained only the crystalline hydroxyapatite phase and amorphous sodium borosilicate glass and carbon nanostructures. The study of the microstructure and fracture morphology of the composites revealed a porous amorphous–crystalline microstructure with a complex specific relief, carbon fibers, and a developed micro- and macropore system. The biogenic hydroxyapatite/glass/carbon fiber composites retain the phase composition and nanostructure of the starting materials and are promising for medical applications.

In the present work magnetite nanopowders were synthesized by chemical precipitation using FeCl 3 ·6H 2 O and FeCl 2 ·4H 2 O (80 °C, maintaining 5 min–1 h) and decomposition of FeC 2 O 4 (470 °C, in hydrocarbon and nitrogen media maintaining 2 h) and investigated by X-ray diffraction analysis, IR spectroscopy and Scanning electron microscopy. Specific surface area and magnetic properties (specific saturation magnetization and coercive force) were also evaluated. It was shown that the time of synthesis did not influence on the phase composition and nanopowder with specific surface area equal to 141 m 2 /g could be prepared using chemical precipitation method for 5 min. Thermal decomposition method was found to allow obtaining of nanopowders with the higher degree crystallinity. It was established that increasing time of chemical precipitation causes decreasing the specific saturation magnetization from to 62 down to 53.5 emu/g and coercive force from 18.1 down to 3.0 Oe. Thermal decomposition method significantly improve magnetic properties and allow to obtain magnetite nanopowder with the specific saturation magnetization 135 emu/g.

Highly-porous bioceramic scaffolds based on biogenic hydroxyapatite with addition of 40 wt.% of glass (wt.%: 45.7 SiO 2 , 28.2 B 2 O 3 , 26.1 Na 2 O) were prepared by foam replication method at 700  С followed by coating of chitosan dissolved in 1% acetic acid solution and drying at 50  С. Bioceramic samples were studied by XRD, IR spectroscopy and SEM. Phase composition, morphology, skeleton density, porosity, compression strength and in vitro tests were evaluated. The results show that, during sintering, the biogenic hydroxyapatite in bioceramic composition is stable and keeps hydroxyapatite phase without secondary phase formation. Chitosan coating shows twofold increase in the compression strength in comparison with pure bioceramics. Moreover, chitosan coating significantly influences on the structure of highly-porous bioceramic scaffolds and dissolution rate in saline. Thus, balanced porosity and dissolution rate make the prepared materials promising for bone marrow stromal cell loading, drug delivery and bone tissue

Bioceramics based on biogenic hydroxyapatite and sodium-borosilicate glass modified with 0; 0.5, 1.0, and 2.0 wt. % copper was prepared by two-stage sintering (1100 and 750 degrees C). According to XRD results, it was established that the introduction of copper influences the volume of the unit crystalline cell of hydroxyapatite after both the first and second stages of sintering. After the latter, the formation of secondary phases (NaCaPO4, Ca2SiO4, Ca-3(SiO4)O and Na2Si3O7) was found for both copper-free and copper-modified composite materials. It was shown that the amount of copper does not affect the phase composition of samples after the final (second) sintering. It was established that copper addition decreases the total porosity of sintered samples (from 15.8 to 11.1 %) with forming an opener porous structure as compared with copper-free bioceramics and makes it possible to increase the compressive strength by 1.7 times.

Дослідження біоактивних властивостей матеріалів на основі гідроксіапатиту (ГА) у поєднанні з іонами міді, що останнім часом викликають зацікавленість сучасних науковців та є функціонально привабливими для широкого спектра медичних застосувань, показали певний рівень антибактеріальних властивостей таких матеріалів [1][2][3][4][5][6].Наприклад, автори роботи [1] перевіряли антимікробну активність мідь-заміщеного ГА (Ca 10