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Study Design. Experimental porcine anterior cervical discectomy and fusion (ACDF) model: a proof-of-concept study. Objective. The effect of monetite synthetic bone graft (SBG) containing calcium pyrophosphate and ß-tricalcium phosphate on cervical spinal fusion in a noninstrumented two-level large animal model. Summary of Background Data. ACDF is the gold standard surgical technique for the treatment of degenerative cervical spinal diseases. However, pseudarthrosis associated with increased patient morbidity occurs in ~2.6% of the surgeries. SBG may enhance bony fusion and subsequently decrease the risk of pseudarthrosis. Recent studies on monetite-based SBGs for use in large cranial defects in humans have shown promising bone healing results, necessitating further investigation of their use in cervical spinal fusion. Materials and Methods. Four adult female Danish Göttingen minipigs received partial cervical anterior discectomy and intervertebral defects at an upper and lower level. One defect was filled with SBG, and the other was left empty. Bony fusion was evaluated using computed tomography (CT) at three-month intervals for 12 months. Fifteen months postsurgery, the animals were euthanized for further ex vivo qualitative histopathologic and micro-CT evaluations. Fusion rates were compared using the Fisher exact test at each time point. Results. Increased interbody bony fusion rates were observed at SBG levels (4/4) compared with control levels (0/4) evaluated by CT at 6 and 9 months postsurgery (P=0.029). Fusion was observed at all SBG levels 12 months postsurgery and at only one control level. Histopathologic evaluation confirmed high-quality interbody bony fusion at all SBG levels and fusion by spondylosis at one control level. Conclusion. This proof-of-concept study provides preliminary evidence of a novel, calcium pyrophosphate-containing, and ß-tricalcium phosphate-containing monetite SBG that promotes bony fusion compared with a negative control in a clinically relevant porcine model of ACDF. [ABSTRACT FROM AUTHOR]

Ca-source of green mussel shells (Perna-Viridis) recovered into precipitated calcium carbonate (PCC) powders via a calcination-dissolution-precipitation pathway is a prospective feedstock for the rapid synthesis of monocalcium phosphate monohydrate (MCPM). In the study, a potential aqueous crystallization process was implemented for MCPM synthesis by blending PCC powders with vaterite (55.20 wt %) and calcite (44.80 wt%) in strongly phosphoric acid with a molarity of 85% (w/w) and varying amounts of water (2–6 mL), followed by rapid evaporation and drying. The resulting product contained at least 90 wt % MCPM and minor monetite according to XRD and FTIR analyses. The morphology of the MCPM product is a prismatic-like shape with grain sizes ranging from 3 to 9 μm, as observed using SEM techniques. DTA/DTG/TG analysis confirms the stability of MCPM products at temperatures up to 100 °C providing benefits for food industries and communities as a stable food additive commodity. • A green mussel shell calcination-dissolution-precipitation pathway for precipitated calcium carbonate (PCC) product. • Synthesis of monocalcium phosphate in a strong acidic phosphoric solution using PCC powders as feedstock. • Monocalcium phosphate and monetite were synthesized quickly and easily at room temperature. • High purity monocalcium phosphate with plate-like morphology was generated. [ABSTRACT FROM AUTHOR]

Composite cements containing brushite, monetite and newberyite as dominating phases were created and used as drug (vancomycin) carriers. Brushite-monetite-newberyite cement with variable composition was obtained by replacing Ca2+ ions with Mg2+ in the initial cement component. Starting powder mixtures for cement preparation synthesized via solid state reaction consisted of MgxCa(3-х)(PO4)2 (x = 0, 0.75, 1.5, 2.25, 3), monocalcium phosphate monohydrate Ca(H2PO4)2·H2O with and without vancomycin as antibacterial agent. 100 mg of powder of a pharmaceutical substance per 1 g of the dry cement powder was added before cement sample preparation. Mixing liquids used were water solutions containing sodium pyrophosphate hexahydrate Na4P2O7·10H2O and citric acid monohydrate C6H8O7·H2O as set-retarding additives. An increase in the concentration of Mg2+ ions entail an increase in pH during preparation and a decrease in porosity of cement sample. Incorporation of vancomycin at the stage of preparation of the cement mixture does not affect the strength characteristics, porosity and pH of the cement stone. The prolongation of the release of vancomycin depends on the composition and characteristics of the cement stone. The activity of vancomycin against Staphylloccoscus aureus and Escherichia coli the process of hydration of cement and its dissolution was confirmed by appropriate tests in vitro. In vivo studies confirm the biocompatibility, resorbability of cements, and the effectiveness of their use as carriers of vancomycin in the treatment of purulent-septic inflammation.

The design principle of osteogenic bone grafts has shifted from immunological inertness to limiting foreign body response to combined osteoimmunomodulatory activity to promote high-quality endogenous bone regeneration. Recently developed immunomodulatory mucin hydrogels have been shown to elicit very low complement activation and suppress macrophage release and activation after implantation in vivo. However, their immunoregulatory activity has not yet been studied in the context of tissue repair. Herein, we synthesized mucin-monetite composite materials and investigated their early osteoimmunomodulation using a critical-size rat bone defect model. We demonstrated that the composites can polarize macrophages towards the M2 phenotype at weeks 1 and 2. The early osteoimmunomodulation enhanced early osteogenesis and angiogenesis and ultimately promoted fracture healing and engraftment (revascularization of the host vasculature) at weeks 6 and 12. Overall, we demonstrated the applicability of mucin-based immunomodulatory biomaterials to enhance tissue repair in tissue engineering and regenerative medicine.

Ceramic materials in Na2O-CaO-P2O5 system were obtained by firing cement-salt stone made from pastes based on powder mixtures including calcium citrate tetrahydrate Ca3(C6H5O7)2∙4H2O, monocalcium phosphate monohydrate (MCPM) Ca(H2PO4)2∙H2O and/or sodium dihydrogen phosphate NaH2PO4. The phase composition of the obtained samples of cement-salt stone after adding water, hardening and drying included brushite CaHPO4∙2H2O, monetite CaHPO4 and also unreacted Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and/or NaH2PO4. The phase composition of ceramics in Na2O-CaO-P2O5 system obtained by firing cement-salt stone was formed due to thermal conversion of hydrated salt and heterophase reactions between components presented in samples during firing. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O and Ca(H2PO4)2∙H2O after firing at 900 °C included β-calcium pyrophosphate (CPP) β-Ca2P2O7. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, and NaH2PO4 after firing at 900 °C included β-sodium rhenanite β-CaNaPO4. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and NaH2PO4 after firing at 900 °C included β-Ca2P2O7, β-CaNaPO4, double calcium-sodium pyrophosphate Na2CaP2O7, and Na-substituted tricalcium phosphate Сa10Na(PO4)7. Obtained ceramic materials in Na2O-CaO-P2O5 system including biocompatible and biodegradable phases could be important for treatments of bone tissue defects by means of approaches of regenerative medicine.

New bone cement type that combines Sr2 + /Mg2 + or Sr2 + /Zn2 + co-substituted nano-hydroxyapatite (n-HAs) with calcium phosphate dibasic and chitosan/gelatin polymers was developed to increase adhesion and cellular response. The cements were physicochemically described and tested in vitro using cell cultures. All cements exhibited quite hydrophilic and had high washout resistance. Cement releases Ca2 + , Mg2 + , Sr2 + , and Zn2 + in concentrations that are suitable for osteoblast proliferation and development. All of the cements stimulated cell proliferation in fibroblasts, endothelial cells, and osteoblasts, were non-cytotoxic, and produced apatite. Cements containing co-substituted n-HAs had excellent cytocompatibility, which improved osteoblast adhesion and cell proliferation. These cements had osteoinductive potential, stimulating extracellular matrix (ECM) mineralization and differentiation of MC3T3-E1 cells by increasing ALP and NO production. The ions Ca2 + , Mg2 + , Zn2 + , and Sr2 + appear to cooperate in promoting osteoblast function. The C3 cement (HA-SrMg5%), which was made up of n-HA co-substituted with 5 mol% Sr and 5 mol% Mg, showed exceptional osteoinductive capacity in terms of bone regeneration, indicating that this new bone cement could be a promising material for bone replacement. [ABSTRACT FROM AUTHOR]

Brushite coatings were obtained on titanium by the method of electrochemical deposition from Ca(NO3)2/NH4H2PO4 electrolyte at Ca/P = 1.67, pH 4, and a constant voltage of 15 V or a current density of 20 mA/cm2 for 20 min. In a medium of 0.01–0.10% polyvinyl alcohol at a constant voltage of 15 V, single-phase brushite or monetite coatings are deposited. The addition of 0.01–0.10% polyvinyl alcohol to the electrolyte during deposition at a constant current density of 20 mA/cm2 leads to the formation of composite calcium phosphate coatings containing brushite, calcium hydroxide, and calcium phosphate of the apatite structure. The bioactivity of calcium phosphate coatings was confirmed by the formation of apatites during their soaking in the Simulated Body Fluid (SBF). Amorphized apatite that formed on brushite coatings during soaking for 2 weeks in SBF crystallizes into β-tricalcium phosphate after heat treatment. The apatite that formed on the composite coating in the SBF crystallizes into a composition of hydroxyapatite and β-tricalcium phosphate. The resulting bioactive calcium phosphate coatings can be used as biocoatings to enhance osseointegration of titanium implants. [ABSTRACT FROM AUTHOR]

Calcium phosphates (CaP) represent an important class of osteoconductive and osteoinductive biomaterials. As proof-of-concept, we show how a multi-component CaP formulation (monetite, beta-tricalcium phosphate, and calcium pyrophosphate) guides osteogenesis beyond the physiological envelope. In a sheep model, hollow dome-shaped constructs were placed directly over the occipital bone. At 12 months, large amounts of bone (∼75%) occupy the hollow space with strong evidence of ongoing remodelling. Features of both compact bone (osteonal/osteon-like arrangements) and spongy bone (trabeculae separated by marrow cavities) reveal insights into function/need-driven microstructural adaptation. Pores within the CaP also contain both woven bone and vascularised lamellar bone. Osteoclasts actively contribute to CaP degradation/removal. Of the constituent phases, only calcium pyrophosphate persists within osseous (cutting cones) and non-osseous (macrophages) sites. From a translational perspective, this multi-component CaP opens up exciting new avenues for osteotomy-free and minimally-invasive repair of large bone defects and augmentation of the dental alveolar ridge.

Microporous ceramic material, based on β-tricalcium phosphate β-Ca3(PO4)2 with grain size 2–5 μm, pore size smaller than 10 mm, and density 1.22 g/cm3 corresponding to ~40% of the theoretical density (3.07 g/cm3) of β-Ca3(PO4)2, was obtained from a powder mixture with a given molar ratio Ca/P = 1.5 after firing at 1100 °C. A homogenized powder mixture of synthetic dicalcium hydrogen phosphates with the molar ratio Ca/P = 1 and calcium citrate tetrahydrate Ca3(C6H5O7)2·4H2O with the molar ratio Ca/P = ∞ was used for microporous ceramic preparation. The phase composition of calcium phosphate powder, synthesized from an aqueous solution of phosphoric acid H3PO4 and calcium carbonate CaCO3 powder, included brushite CaHPO4·2H2O as the predominant phase. Formation of β-tricalcium phosphate β-Ca3(PO4)2 during firing occurred due to the heterophase interaction of the products of thermal decomposition of the components of the starting powder mixture, namely, calcium pyrophosphate Ca2P2O7 and calcium oxide CaO. The formation of arch-like structures from β-tricalcium phosphate β-Ca3(PO4)2 grains, which were tightly sintered together, hindered the shrinkage of ceramics. The microporous ceramics obtained, based on β-tricalcium phosphate β-Ca3(PO4)2, can be recommended as a biocompatible and biodegradable material for treatment of bone defects and as a substrate for bone-cell cultivation.

Objective: A triphasic bone graft block composed of gypsum, brushite, and monetite is expected to be better for regenerating bone than a gypsum-hydroxyapatite-tricalcium phosphate block. Therefore, the aim of this study was to fabricate and evaluate the mechanical properties of a newly developed triphasic block composed of gypsum, brushite, and monetite. Materials and method: Triphasic blocks were prepared by mixing calcium sulfate hemihydrate, brushite, and monetite powders with distilled water at a powder-to-liquid ratio of 0.5. The content of calcium sulfate hemihydrate was fixed at 50%, and the contents of brushite and monetite powders were varied. After molding and setting, the obtained blocks were characterized, and their mechanical properties were evaluated. Results: The triphasic blocks were prepared and could maintain their shape without collapsing. The XRD characterization of the obtained triphasic blocks showed that only three phases existed in the block. Calcium sulfate hemihydrate was transformed into its dihydrate form and provided mechanical strength to the block through a setting mechanism. The transformation of calcium sulfate hemihydrate into its dihydrate crystals formed an interlocked structure that was disrupted in triphasic blocks, as observed in SEM images. The disruption of the interlocked structure resulted in lower mechanical strength of the obtained triphasic blocks compared to the set gypsum control. The variation in brushite and monetite composition did not affect the mechanical properties of the triphasic blocks. Conclusion: The triphasic gypsum-brushite-monetite block was successfully prepared, and no other crystal phases were found. The triphasic blocks could maintain their shape after setting. The addition of brushite and monetite powders disrupted the interlocked structure of the set gypsum crystal, resulting in a decrease in mechanical strength. Furthermore, the variation in brushite and monetite powders did not affect the mechanical properties of the triphasic blocks.

Biocompatibility of ceramic materials in Ca2P2O7-Ca(PO3)2 system was investigated using different methods, including in vitro and in vivo tests. Ceramic materials in the Ca2P2O7-Ca(PO3)2 system were obtained by annealing cement-salt stone based on powder mixtures of calcium citrate tet-rahydrate Ca3(C6H5O7)2·4H2O and monocalcium phosphate monohydrate (MCPM) Ca(H2PO4)2·H2O. The phase composition of cement-salt stone included brushite, monetite as a result of chemical reaction of starting components after adding of water. The presence of citric acid as by-product of chemical reaction, leads to increase the setting time of the cement-salt stone. Highly concentrated aqueous suspensions based on calcium citrate and MCPM powders providing content of calcium polyphosphate Ca(PO3)2 up to 20 wt % in ceramics were used for designing bioresorbable materials. The presence of an excess of monocalcium phosphate monohydrate makes it possible to reduce the annealing temperature of ceramics, which is associated with the formation of a lower melting phase of Ca(PO3)2. In vivo tests shown that obtained ceramic materials can be recommended for regenerative treatments for bone defects.

In synthetic fabrication, the process parameters decide the growth nucleation, phase translation, and the evolution of morphological facets of nanostructured materials. This work demonstrates the formation of different crystallographic phases of calcium phosphate by the influence of pH from acidic to alkaline conditions and also investigated their bone regeneration, protein adsorption, and pro‐angiogenic properties. Present results illustrate that the alteration of pH is the crucial factor for the synthesis of calcium phosphate (CP) phases. The structural analysis reveals the monetite (CaHPO4) phase with a triclinic crystal system for pH 5, dual‐phase of monetite combined with hydroxyapatite at the neutral pH 7, and pure phase of hydroxyapatite (Ca10[PO4]6OH2) with hexagonal structure at pH 10. Microscopic analysis portrays the cubic and rod‐like morphologies by changing the pH values. FTIR and RAMAN spectroscopic analyses confirm the stretching, bending, and vibrational modes of dominant phosphate groups of different CP phases. Further, the biocompatibility of the prepared CP phases was examined by hemolysis assay, which showed less than 2% of lysis and enhanced cell viability. Moreover, the bioactivity study revealed rapid mineralization and a higher protein adsorption rate for the monetite CP phase (M‐CP). Subsequently, the chick embryo angiogenesis assay elucidated 33% higher neovascularization for M‐CP compared with the other two CP phases. The fabricated M‐CP nanostructure constitutes a promising candidate for biomedical applications. [ABSTRACT FROM AUTHOR]

Monetite (MC) is a type of calcium phosphate cement (CPC). It has various morphologies, continuous degradation and absorption properties; however, its high porosity will affect its mechanical properties. There is minimal research on MC is immature. Amorphous calcium phosphate (ACP) is widely used and exhibits good biocompatibility; however, it is unstable. In this study, MC was combined with ACP at different weight ratios to form new types of bone cements. The mechanical properties, biocompatibility, and inductive ability for osteogenesis and osteoclasts of different MC/ACP composite bone cements were evaluated. The biocompatibility and effects on osteogenic and osteoclast differentiation of MC/ACP composite bone cements were investigated in vitro using mouse bone marrow mesenchymal stem cells (mBMMSCs) and mouse monocyte/macrophage cell line RAW 264.7. RAW 264.7 cells can differentiate into osteoclasts by osteoclast differentiation. The results indicated that the overall performance of the MC/ACP composite bone cement was better than that of the MC or ACP alone. Compared to the other groups, the biocompatibility of MC75 (75 wt% MC and 25 wt% ACP) was optimal; it was able to induce mBMMSCs osteogenesis to a greater extent. MC75 was the least favorable for the proliferation, migration, and differentiation of osteoclasts. The mechanical properties, setting time and injectability of MC75 meet clinical application requirements. This study demonstrated that MC75 is a promising bone cement for repairing bone defects. [ABSTRACT FROM AUTHOR]

Ceramic materials in Na2O-CaO-P2O5 system were obtained by firing cement-salt stone made from pastes based on powder mixtures including calcium citrate tetrahydrate Ca3(C6H5O7)2∙4H2O, monocalcium phosphate monohydrate (MCPM) Ca(H2PO4)2∙H2O and/or sodium dihydrogen phosphate NaH2PO4. The phase composition of the obtained samples of cement-salt stone after adding water, hardening and drying included brushite CaHPO4∙2H2O, monetite CaHPO4 and also unreacted Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and/or NaH2PO4. The phase composition of ceramics in Na2O-CaO-P2O5 system obtained by firing cement-salt stone was formed due to thermal conversion of hydrated salt and heterophase reactions between components presented in samples during firing. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O and Ca(H2PO4)2∙H2O after firing at 900 °C included β-calcium pyrophosphate (CPP) β-Ca2P2O7. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, and NaH2PO4 after firing at 900 °C included β-sodium rhenanite β-CaNaPO4. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and NaH2PO4 after firing at 900 °C included β-Ca2P2O7, β-CaNaPO4, double calcium-sodium pyrophosphate Na2CaP2O7, and Na-substituted tricalcium phosphate Сa10Na(PO4)7. Obtained ceramic materials in Na2O-CaO-P2O5 system including biocompatible and biodegradable phases could be important for treatments of bone tissue defects by means of approaches of regenerative medicine. [ABSTRACT FROM AUTHOR]

Generally, the metallic implants do not exhibit any bio-integration properties in contact with bone tissues. To improve the interfacial properties of metallic implants in contact with bone, the coatings with thin biocompatible films are used. Two methods to coating titanium implants with hydroxyapatite are described. The first is a two phase method, where by cathodic polarization is deposed a monetite film followed by an alkaline treatment when the monetite is converted to hydroxyapatite. The second method is a biomimetic deposition on an alkaline activate titanium surface, using a five time more concentrated simulated body fluid (5xSBF). After deposition this samples was drying at 120℃ and was sintered at 700℃ for three hours. Optical microscopy, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray (EDX) were used to characterize structure, morphology and compositions of the deposed films. In this study, electrochemical deposition and biomimetic deposition of hydroxyapatite are compared.

Sodium-rich phosphate and silicate melt inclusions as well as chromite and schreibersite grains have been studied in the troilite nodule of the Darinskoe IIC iron meteorite. Sulfide association (K-sulfides, pentlandite, chalcopyrite, cubanite ?) commonly occurs around the inclusions. Many phosphate inclusions are altered and represented now by unidentified hydrated Сa–Fe–Mn–Mg-phosphates, which are the replacement products of unhydrated high-Na orthophosphates. Buchwaldite NaCa(PO4) was only found as primary phase of the inclusions; and monetite CaH(PO4) was determined among secondary phosphates. Silicate inclusions contain glass, sometimes Fe-rich serpentine (?), and phosphate. Silicate glasses have highly siliceous and high-Na alkaline composition (SiO2—60.8–74.4 wt %, Na2O + K2O—13.9–16.8 wt %), and are enriched in TiO2 (2.2–11.2 wt %) and Cr2O3 (1.5–3.4 wt %) and virtually free in Al2O3 (<0.2 wt %). It is suggested that the inclusions represent the latest crystallization products of the Darinskoe meteorite formed due to silicate–natrophosphate liquid immiscibility in a sulfide melt. The chemical compositions of the key meteorite minerals, as well as data on rare and potentially new minerals (Cl-free djerfisherite, "Cu-djerfisherite" K7(Cu,Fe)25S26, NiTe, Ni3Fe2, Os–Ir–Pt-rich Fe–Ni alloys, czochralskiite) are also given in the paper. Raman spectra for buchwaldite and monetite are presented. [ABSTRACT FROM AUTHOR]

A triphasic bone graft block composed of gypsum, brushite, and monetite is expected to be better for regenerating bone than a gypsum-hydroxyapatite-tricalcium phosphate block. Therefore, the aim of this study was to fabricate and evaluate the mechanical properties of a newly developed triphasic block composed of gypsum, brushite, and monetite. Triphasic blocks were prepared by mixing calcium sulfate hemihydrate, brushite, and monetite powders with distilled water at a powder-to-liquid ratio of 0.5. The content of calcium sulfate hemihydrate was fixed at 50%, and the contents of brushite and monetite powders were varied. After molding and setting, the obtained blocks were characterized, and their mechanical properties were evaluated. The triphasic blocks were prepared and could maintain their shape without collapsing. The XRD characterization of the obtained triphasic blocks showed that only three phases existed in the block. Calcium sulfate hemihydrate was transformed into its dihydrate form and provided mechanical strength to the block through a setting mechanism. The transformation of calcium sulfate hemihydrate into its dihydrate crystals formed an interlocked structure that was disrupted in triphasic blocks, as observed in SEM images. The disruption of the interlocked structure resulted in lower mechanical strength of the obtained triphasic blocks compared to the set gypsum control. The variation in brushite and monetite composition did not affect the mechanical properties of the triphasic blocks. The triphasic gypsum-brushite-monetite block was successfully prepared, and no other crystal phases were found. The triphasic blocks could maintain their shape after setting. The addition of brushite and monetite powders disrupted the interlocked structure of the set gypsum crystal, resulting in a decrease in mechanical strength. Furthermore, the variation in brushite and monetite powders did not affect the mechanical properties of the triphasic blocks. [ABSTRACT FROM AUTHOR]

Microporous ceramic material, based on β-tricalcium phosphate β-Ca3(PO4)2 with grain size 2–5 μm, pore size smaller than 10 mm, and density 1.22 g/cm3 corresponding to ~40% of the theoretical density (3.07 g/cm3) of β-Ca3(PO4)2, was obtained from a powder mixture with a given molar ratio Ca/P = 1.5 after firing at 1100 °C. A homogenized powder mixture of synthetic dicalcium hydrogen phosphates with the molar ratio Ca/P = 1 and calcium citrate tetrahydrate Ca3(C6H5O7)2·4H2O with the molar ratio Ca/P = ∞ was used for microporous ceramic preparation. The phase composition of calcium phosphate powder, synthesized from an aqueous solution of phosphoric acid H3PO4 and calcium carbonate CaCO3 powder, included brushite CaHPO4·2H2O as the predominant phase. Formation of β-tricalcium phosphate β-Ca3(PO4)2 during firing occurred due to the heterophase interaction of the products of thermal decomposition of the components of the starting powder mixture, namely, calcium pyrophosphate Ca2P2O7 and calcium oxide CaO. The formation of arch-like structures from β-tricalcium phosphate β-Ca3(PO4)2 grains, which were tightly sintered together, hindered the shrinkage of ceramics. The microporous ceramics obtained, based on β-tricalcium phosphate β-Ca3(PO4)2, can be recommended as a biocompatible and biodegradable material for treatment of bone defects and as a substrate for bone-cell cultivation. [ABSTRACT FROM AUTHOR]

Biocompatibility of ceramic materials in Ca2P2O7-Ca(PO3)2 system was investigated using different methods, including in vitro and in vivo tests. Ceramic materials in the Ca2P2O7-Ca(PO3)2 system were obtained by annealing cement-salt stone based on powder mixtures of calcium citrate tet-rahydrate Ca3(C6H5O7)2·4H2O and monocalcium phosphate monohydrate (MCPM) Ca(H2PO4)2·H2O. The phase composition of cement-salt stone included brushite, monetite as a result of chemical reaction of starting components after adding of water. The presence of citric acid as by-product of chemical reaction, leads to increase the setting time of the cement-salt stone. Highly concentrated aqueous suspensions based on calcium citrate and MCPM powders providing content of calcium polyphosphate Ca(PO3)2 up to 20 wt % in ceramics were used for designing bioresorbable materials. The presence of an excess of monocalcium phosphate monohydrate makes it possible to reduce the annealing temperature of ceramics, which is associated with the formation of a lower melting phase of Ca(PO3)2. In vivo tests shown that obtained ceramic materials can be recommended for regenerative treatments for bone defects. [ABSTRACT FROM AUTHOR]

Pendahuluan: Kerusakan tulang yang besar membutuhkan prosedur penambahan bone graft untuk membantu meregenerasi jaringan tulang. Monetite memiliki potensi yang sangat baik sebagai kandidat bone graft kedokteran gigi. Hidrotermal banyak digunakan dalam sintesis bone graft karena dapat mempercepat reaksi. Tujuan penelitian membuat monetite dari granul gipsum sebagai prekursor dengan menggunakan metode hidrotermal sebagai kandidat bone graft kedokteran gigi. Metode: Jenis penelitian ini merupakan eksperimental laboratoris. Granul gipsum dibuat dengan menggerus blok gypsum hasil reaksi setting kalsium sulfat hemihidrat dan aquadest dengan rasio serbuk terhadap liqud sebesar 2,5. Selanjutnya, granul gipsum dikonversi menjadi granul monetite dengan direndam di dalam larutan 2 mol/L NaH2PO4 pada suhu 150oC dalam kondisi hidrotermal selama 24 jam. Hasil: Berdasarkan hasil uji XRD, granul monetite dapat terbentuk. Hasil gambar optik granul monetite secara makroskopik menunjukkan tidak mengalami perubahan dibandingkan dengan granul gipsum. Simpulan: Granul monetite sebagai kandidat bone graft kedokteran gigi berhasil dibuat dengan metode hidrotermal melalui perendaman granul gipsum dalam larutan 2 mol/L NaH2PO4 pada suhu 150oC selama 24 jam. ABSTRACT Introduction: Massive bone damage requires a procedure of bone graft addition to helping regenerate the bone tissue. Monetite has excellent potential as a dental bone graft candidate. Hydrothermal is widely used in bone graft synthesis due to its catalyst property. The purpose of this research was to fabricate the monetite from gypsum granules as a precursor with the hydrothermal method as the dental bone graft candidate. Methods: This research was an experimental laboratory. Gypsum granules were made by grinding gypsum blocks resulting from the setting reaction of calcium sulfate hemihydrate and aquadest with a powder to liquid ratio of 2.5. Furthermore, the gypsum granules were converted into monetite granules by immersing them in a solution of 2 mol/L of NaH2PO4 at a temperature of 150°C under hydrothermal conditions for 24 hours. Results: Based on the XRD test results, monetite granules was able to be formed. The results of the macroscopic optical image of the monetite granules showed no change compared to the gypsum granules. Conclusions: Monetite granules as dental bone graft candidate are successfully prepared using the hydrothermal method by immersing gypsum granules in a solution of 2 mol/L of NaH2PO4 at 150oC for 24 hours.

Ceramic samples based on β-calcium pyrophosphate β-Ca2P2O7 were prepared from powders of γ-calcium pyrophosphate γ-Ca2P2O7 with preset molar ratios Ca/P = 1, 0.975 and 0.95 using firing at 900, 1000, and 1100 °C. Calcium lactate pentahydrate Ca(C3H5O3)2⋅5H2O and monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O were treated in an aqua medium in mechanical activation conditions to prepare powder mixtures with preset molar ratios Ca/P containing calcium hydrophosphates with Ca/P = 1 (precursors of calcium pyrophosphate Ca2P2O7). These powder mixtures containing calcium hydrophosphates with Ca/P = 1 and non-reacted starting salts were heat-treated at 600 °C after drying and disaggregation in acetone. Phase composition of all powder mixtures after heat treatment at 600 °C was presented by γ-calcium pyrophosphate γ-Ca2P2O7 according to the XRD data. The addition of more excess of monocalcium phosphate monohydrate Ca(H2PO4)2·H2O (with appropriate molar ratio of Ca/P = 1) to the mixture of starting components resulted in lower dimensions of γ-calcium pyrophosphate (γ-Ca2P2O7) individual particles. The grain size of ceramics increased both with the growth in firing temperature and with decreasing molar ratio Ca/P of powder mixtures. Calcium polyphosphate (t melt = 984 °C), formed from monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O, acted similar to a liquid phase sintering additive. It was confirmed by tests in vitro that prepared ceramic materials with preset molar ratios Ca/P = 1, 0.975, and 0.95 and phase composition presented by β-calcium pyrophosphate β-Ca2P2O7 were biocompatible and could maintain bone cells proliferation. [ABSTRACT FROM AUTHOR]

Generally, the metallic implants do not exhibit any bio-integration properties in contact with bone tissues. To improve the interfacial properties of metallic implants in contact with bone, the coatings with thin biocompatible films are used. Two methods to coating titanium implants with hydroxyapatite are described. The first is a two phase method, where by cathodic polarization is deposed a monetite film followed by an alkaline treatment when the monetite is converted to hydroxyapatite. The second method is a biomimetic deposition on an alkaline activate titanium surface, using a five time more concentrated simulated body fluid (5xSBF). After deposition this samples was drying at 120°C and was sintered at 700°C for three hours. Optical microscopy, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray (EDX) were used to characterize structure, morphology and compositions of the deposed films. In this study, electrochemical deposition and biomimetic deposition of hydroxyapatite are compared. [ABSTRACT FROM AUTHOR]

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The ability of strontium ion to inhibit the abnormally high bone resorption, which occurs in pathologies characterized by loss of bone substance, has stimulated a number of research on strontium substituted/doped calcium phosphates. However, no information was available up to now on strontium substitution to calcium in the structure of α-CaHPO 4 , monetite, in spite of the involvement of this phosphate in the composition of biomaterials for hard tissue substitution/repair and although it is isomorphous with α-SrHPO 4. Herein, we investigated the substitution of strontium to calcium in the structure of α-CaHPO 4 , as well as the replacement of calcium for strontium in the structure of a further polymorph of SrHPO 4 , namely β-SrHPO 4. To this purpose, monetite at increasing degree of strontium substitution for calcium was synthesized by means of direct synthesis in aqueous solution, as well as through thermal treatment of strontium-substituted brushite; whereas the synthesis of β-SrHPO 4 was carried out at low temperature. The results of structural refinements, spectroscopic analysis and electron microscopy investigation indicate that the method of synthesis has a great influence on the range of strontium incorporation into α-CaHPO 4 , which can reach 100 at%. The morphology of the synthesized materials is also remarkably dependent on composition. The analysis of the products synthesized at low temperature shows that the upper limit of possible substitution of calcium to strontium in the structure of β-SrHPO 4 is much more limited, just up to about 20 at%. Moreover, powder X-ray analysis of β-SrHPO 4 states that it crystallizes with a monoclinic cell in the space group P2 1 /c. [ABSTRACT FROM AUTHOR]

This work aims to investigate the coexistence of the poly(phospho-siloxo) networks and calcium phosphates on the compressive strengths of the acid-based geopolymers obtained at room temperature. Waste fired brick and phosphoric acid were used as an aluminosilicate and chemical reagent, respectively. Calcium aluminate hydrate was prepared by mixing calcium hydroxide from the calcined eggshell and calcined bauxite. Calcium silicate hydrate was obtained by the mixture of rice husk ash and calcium hydroxide. The molar ratios CaO/Al2O3 and CaO/SiO2 in the calcium aluminate and calcium silicate hydrates are equals to 1.0. The X-ray patterns of the acid-based geopolymers indicate the broad hump structure between 18 and 38°(2θ). In addition to this broad band, those from the mixture of calcium sources show the reflection peaks of monetite and brushite. The compressive strength of the reference is 56.43 MPa. Those obtained with the addition of 10, 20, 40 and 50 g of calcined eggshell are 30.15, 22.85, 21.16 and 13.47 MPa, respectively. The ones from calcium aluminate hydrate are 32.62, 31.58, 17.83 and 16.33 MPa, respectively. Whereas those containing calcium silicate hydrate are 44.02, 42.71, 40.19 and 18.59 MPa, respectively. This work demonstrates that the formation of calcium phosphates in the structure of the acid-based geopolymers decreases the poly(phospho-siloxo) chains and therefore reduces their compressive strengths. The moderate addition of calcium silicate hydrate reduces slightly the compressive strengths of the acid-based geopolymers which can be comparable to the one of CEM II 42.5R. [ABSTRACT FROM AUTHOR]

Ceramics in the K2O–CaO–SO3–P2O5 system has been prepared from powder mixtures of potassium hydrogen sulfate KHSO4 and calcium hydroxyapatite Ca10(PO4)6(OH)2 at molar ratios KHSO4/Ca10(PO4)6(OH)2 = 2/1, 4/1, and 6/1. The powder mixtures were obtained in acetone under mechanical activation conditions using a planetary mill. After homogenization, the phase composition of powder mixtures included monetite CaHPO4, singenite K2Ca(SO4)2⋅H2O, and calcium hydroxyapatite Сa10(PO4)6(OH)2. After firing at 700–900°C the phase composition of ceramics manufactured from the powder mixtures included phases of potassium-substituted tricalcium phosphate Сa10K(PO4)7 and calciolangbeinite K2Ca2(SO4)3, as well as potassium sulfate K2SO4 at molar ratios KHSO4/Ca10(PO4)6(OH)2 = 4/1 and 6/1. Ceramic materials whose phase composition includes calciolangbeinite K2Ca2(SO4)3 and potassium-substituted tricalcium phosphate Сa10K(PO4)7 can be used as resorbable porous material for curing defects of bone tissue by regenerative medicine methods or as a matrix on designing luminescent/thermoluminescent materials. Ceramic materials in K2O–CaO–SO3–P2O5 system have been obtained for the first time, therefore, additional studies are necessary to determine the optimal phase ratio for the noted applications. [ABSTRACT FROM AUTHOR]

Powders of calcium pyrophosphate Ca2P2O7 of γ- and β-modifications have been obtained using the thermal conversion of brushite CaHPO4⋅2H2O synthesized from phosphoric acid H3PO4 and calcium carbonate CaCO3 at a molar ratio P/Ca = 1.1. The resulting powders can be used to create various functional materials, including biocompatible and bioresorbable materials for the treatment of bone defects. [ABSTRACT FROM AUTHOR]

This review recognizes a unique calcium phosphate (CaP) phase known as monetite or dicalcium phosphate anhydrous (DCPA, CaHPO 4), and presents an overview of its properties, processing, and applications in orthopedics. The motivation for the present effort is to highlight the state-of-the-art research and development of monetite and propel the research community to explore more of its potentials in orthopedics. After a brief introduction of monetite, we provide a summary of its various synthesis routes like dehydration, solvent-based, energy-assisted processes and also discuss the formation of different crystal structures with respect to the synthesis conditions. Subsequently, we discuss the material's noteworthy physico-chemical properties including the crystal structure, vibrational spectra, solubility, thermal decomposition, and conversion to other phases. Of note, we focus on the biological (in vitro and in vivo) properties of monetite, given its ever-increasing popularity as a biomaterial for medical implants. Appropriately, we discuss various orthopedic applications of monetite as bone cement, implant coatings, granules for defect fillers, and scaffolds. Many in vitro and in vivo studies confirmed the favorable osteointegration and osteoconduction properties of monetite products, along with a better balance between implant resorption and new bone formation as compared to other CaP phases. The review ends with translational aspects of monetite and presents thoughts about its possible future research directions. Further research may explore but not limited to improvements in mechanical strength of monetite-based scaffolds, using monetite particles as a therapeutic agent delivery, and tissue engineering strategies where monetite serves as the biomaterial. This is the first review that focusses on the favorable potential of monetite for hard tissue repair and regeneration. The article accurately covers the "Synthesis-Structure-Property-Applications" correlations elaborating on monetite's diverse material properties. Special focus is put on the in vitro and in vivo properties of the material highlighting monetite as an orthopedic material-of-choice. The synthesis techniques are discussed which provide important information about the different fabrication routes for monetite. Most importantly, the review provides comprehensive knowledge about the diverse biomedical applications of monetite as granules, defect--specific scaffolds, bone cements and implant coatings. This review will help to highlight monetite's potential as an effective regenerative medicine and catalyze the continuing translation of this bioceramic from the laboratory to clinics. [Display omitted] [ABSTRACT FROM AUTHOR]

The new era of science and technology signifies the control over the size and shape of materials. The size and shape variation plays a crucial role in determining the properties of the material and promises a potential application of these materials. The present study focuses on the fabrication of the most important inorganic biomaterial, namely, calcium hydroxyapatite (Ca10(PO4)6(OH)2) (HA) in a nano range having uniform morphology and high surface to volume ratio. HA particles were successfully synthesized by the hydrothermal homogenous precipitation, having whiskers and cubic shaped particle morphology with high crystallinity in size range of 6.1 nm and 9.7 nm, respectively. The morphological features of the particles were further analyzed by Scanning electron microscope (SEM), and the structural evolution was studied by Fourier transform infrared spectroscopy (FT-IR) and X-Ray diffraction analysis (XRD). Urea was used as a precipitating agent to raise pH and promote nucleation & rapid growth of HA crystals at low supersaturation. The effect of different reaction parameters on HA particle morphology was also investigated. Aging time showed a sensitive dependence on the morphological features of HA particles, and the pH of a solution had a vital role in the formation of various crystal phases of calcium phosphate, which served as a precursor in HA formation. [ABSTRACT FROM AUTHOR]

The implementation of a sustainable development strategy holds the potential to enhance productivity, profitability, and overall efficiency by leveraging by-products from other industries. In plaster manufacturing the substitution of natural gypsum with synthetic gypsum is worth exploring. Phosphogypsum (PG) represents a significant fraction of synthetic gypsum production, arising as a by-product of phosphoric acid manufacturing. However, the presence of impurities in PG, particularly phosphorus, poses challenges to its use as a plaster material. To identify the phases present in PG, quantify their occurrences and understand their effects on dehydration and hydration processes, our study aimed to examine simplified models. These models are specifically designed to provide insights into the underlying mechanisms governing the hydration reactivity of hemihydrate. Pure gypsum and brushite were synthesized, and mechanical mixing was carried out to explore how brushite affects the characteristics of gypsum. Additionally, a solid solution of Ca(SO 4) 1-x (HPO 4) x ·2H 2 O, where 0 < x < 1, was prepared to characterize and quantify the syncrystallized HPO 4 2− as well as the effects of this impurity on typical gypsum use cases. The synthesized materials underwent physical and chemical characterization using SEM, XRD, IR spectroscopy, DSC, pH and conductivity measurements, and ion chromatography. The results demonstrated that the HPO 4 2− ions can substitute for sulfate ions in gypsum to form solid solutions. The maximum quantity of HPO 4 2− ions in the gypsum lattice is approximately 10%, leading to the crystallization of gypsum into sand rose shape rather than needle crystals. As the concentration of HPO 4 2− ions increases, a new phase known as ardealite (Ca(SO 4) 1-x (HPO 4) x ·2H 2 O) with 0.42 < x < 0.54 emerges, followed by brushite (CaHPO 4 ·2H 2 O). During the calcination of brushite at 160 °C, a mixture of brushite and monetite formed that exhibits different properties compared to its natural counterpart. In the presence of syncrystallized HPO 4 2− ions, the transformation from anhydrite III to anhydrite II occurred at higher temperatures than for pure gypsum. The reactivity of calcined samples indicate that HPO 4 2− ions from the dehydration products of brushite caused a delay in hydration, with the maximum delay observed at a calcination temperature of 160 °C. At this temperature, monetite begins to crystallize, and it is characterized by its inert nature, exhibiting no reactivity with water. This explains the observed decrease in setting times as the calcination temperature rises. Moreover, syncrystallized HPO 4 2− ions induced a significant delay in the hydration process. Our research revealed that adjusting the calcination temperature can mitigate the retarding effect associated with this impurity, suggesting an industrial tendency to use the lowest possible temperature during the calcination process of PG containing syncrystallized phosphate impurity. In addition, we have observed that adjusting the pH of the mixing water to lower values can significantly accelerate setting times. [ABSTRACT FROM AUTHOR]

Ceramic samples based on β-calcium pyrophosphate β-Ca2P2O7 were prepared from powders of γ-calcium pyrophosphate γ-Ca2P2O7 with preset molar ratios Ca/P = 1, 0.975 and 0.95 using firing at 900, 1000, and 1100 °C. Calcium lactate pentahydrate Ca(C3H5O3)2⋅5H2O and monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O were treated in an aqua medium in mechanical activation conditions to prepare powder mixtures with preset molar ratios Ca/P containing calcium hydrophosphates with Ca/P = 1 (precursors of calcium pyrophosphate Ca2P2O7). These powder mixtures containing calcium hydrophosphates with Ca/P = 1 and non-reacted starting salts were heat-treated at 600 °C after drying and disaggregation in acetone. Phase composition of all powder mixtures after heat treatment at 600 °C was presented by γ-calcium pyrophosphate γ-Ca2P2O7 according to the XRD data. The addition of more excess of monocalcium phosphate monohydrate Ca(H2PO4)2·H2O (with appropriate molar ratio of Ca/P = 1) to the mixture of starting components resulted in lower dimensions of γ-calcium pyrophosphate (γ-Ca2P2O7) individual particles. The grain size of ceramics increased both with the growth in firing temperature and with decreasing molar ratio Ca/P of powder mixtures. Calcium polyphosphate (t melt = 984 °C), formed from monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O, acted similar to a liquid phase sintering additive. It was confirmed by tests in vitro that prepared ceramic materials with preset molar ratios Ca/P = 1, 0.975, and 0.95 and phase composition presented by β-calcium pyrophosphate β-Ca2P2O7 were biocompatible and could maintain bone cells proliferation.

Calcium phosphate powder were synthesized from aqueous solutions of calcium lactate Ca(C3H5O3)2 and ammonium hydrophosphate (NH4)2HPO4 at a Ca/P = 1 molar ratio. According to the XRD data, the phase composition of as-synthesized powder consisted of brushite CaHPO4 ⋅ 2H2O and hydroxyapatite Ca10(PO4)6(OH)2. After heat treatment at 350–600°C, the powder was colored dark brown owing to the destruction of the by-product of the reaction. The composition of the powder heat-treated at 350°C included monetite CaHPO4 and hydroxyapatite Ca10(PO4)6(OH)2, and the powder heat-treated at 600°C consists of hydroxyapatite Ca10(PO4)6(OH)2 and γ-calcium pyrophosphate γ-Ca2P2O7. The phase composition of ceramic obtained from the synthesized powder after sintering at 1100°C consisted of β-calcium pyrophosphate β-Ca2P2O7 and β‑tricalcium phosphate β-Ca3(PO4)2. The colored after the heat treatment in a range of 350–600°C powders can be used as a starting for the molding of porous biocompatible calcium phosphate composite materials with the given geometry of the porous space by stereolithographic printing. The synthesized powder can be recommended for the development of biocompatible and biodegradable both ceramic composite materials and composites with polymer or inorganic matrix for bone implants. [ABSTRACT FROM AUTHOR]

Background The quest for an ideal bone grafting material has been ongoing for decades. Calcium phosphate, alone or in combination with other materials in natural bone, has been shown to aid in bone regeneration effectively. Monetite exhibits superior solubility and resorption rates among calcium phosphates, rendering it an optimal choice for bone regeneration applications. However, the degradation rate of the Monetite is much faster than that of all the other calcium phosphates. Hence, we have added Europium onto the matrix to alter the degradation profile and enhance the osteogenic ability of the prepared matrix. Materials and methods An exclusive Europium-Monetite composite was synthesized employing eco-friendly techniques involving Cissus quadrangularis.  The osteogenic potential was gauged using the MG-63 cell line through a calcium mineralization assay employing an Alizarin Red solution, collagen estimation, and an alkaline phosphatase (ALP) assay. The composite's cytocompatibility was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay across different concentrations ranging from 12.5 µg to 100 µg. Results Scanning electron microscopy (SEM) analysis of the Europium-Monetite composite revealed a sheet-like arrangement in stacks, and the ATR-IR confirmed the presence of elements Ca, P, and Eu. The osteogenic potential, analyzed by ALP activity, calcium mineralization, and collagen staining, was 10% higher than that of the control (Monetite).  Conclusion The prepared novel Europium-Monetite calcium phosphate complex can enhance the osteogenic potential and could be a promising material for bone regeneration/tissue engineering. The newly created Europium-Monetite calcium phosphate complex holds promise for various bone grafting applications, including integration into scaffolds and as a coating for implants., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Suresh et al.)

The capacity of a nanostructured multicomponent material composed of Zn-substituted monetite, amorphous calcium phosphate, hydroxyapatite and silica gel (MSi) to promote vertical bone augmentation was compared with anorganic bovine bone (ABB) and synthetic β-tricalcium phosphate (β-TCP). The relation between biological behavior and physicochemical properties of the materials was also studied. The in vivo study was conducted in a vertical bone augmentation model in rabbit calvaria for 10 weeks. Significant differences in the biological behavior of the materials were observed. MSi showed significantly higher bone regeneration (39%) than ABB and β-TCP (24%). The filled cylinder volume was similar in MSi (92%) and ABB (91%) and significantly lower in β-TCP (81%) implants. In addition, β-TCP showed the highest amount of non-osteointegrated particles (17%). MSi was superior to the control materials because it maintains the volume of the defect almost full, with the highest bone formation, the lowest number of remaining particles, which are almost fully osteointegrated and having the lowest amount of connective tissue. Besides, the bone formed was mature, with broad trabeculae, high vascularization and osteogenic activity. MSi resorbs gradually over time with an evident increment of the porosity and simultaneous colonization for vascularized new bone. In addition, the osteoinductive behavior of MSi material was evidenced.

Bone grafting procedures are commonly used to manage bone defects in the craniofacial region. Monetite is an excellent biomaterial option for bone grafting, however, it is limited by lack of osteoinduction. Several molecules can be incorporated within the monetite matrix to promote bone regeneration. The aim was to investigate whether incorporating bone forming drug conjugates (C3 and C6) within monetite can improve their ability to regenerate bone in bone defects. Bilateral bone defects were created in the mandible of 24 Sprague–Dawley rats and were then packed with monetite control, monetite+C3 or monetite+C6. After 2 and 4 weeks, post‐mortem samples were analyzed using microcomputed tomography, histology and back‐scattered electron microscopy to calculate the percentages of bone formation and remaining graft material. At 2 and 4 weeks, monetite with C3 and C6 demonstrated higher bone formation than monetite control, while monetite+C6 had the highest bone formation percentage at 4 weeks. There were no significant differences in the remaining graft material between the groups at 2 or 4 weeks. Incorporating these anabolic drug conjugates within the degradable matrix of monetite present a promising bone graft alternative for bone regeneration and repair in orthopedic as well as oral and maxillofacial applications. [ABSTRACT FROM AUTHOR]

Calcium phosphate ceramics, with the phase composition represented by β-calcium pyrophosphate β-Ca2P2O7, was obtained from a powder mixture of calcium hydroxyapatite Ca10(PO4)6(OH)2, monocalcium phosphate monohydrate Ca(H2PO4)2 · H2O, and sodium hydrogen phosphate Na2HPO4. The powder mixture was preliminarily homogenized in acetone using a planetary mill. This treatment resulted in the chemical reaction between the starting components to form monetite, calcium hydrogen phosphate CaHPO4 (precursor of calcium pyrophosphate Ca2P2O7). According to the XRD data, sodium hydrogen phosphate Na2HPO4 when present in an amount of 5 wt % in the starting mixture had no effect on the phase composition of the powder after homogenization and of the ceramics after annealing. Sodium pyrophosphate Na4P2O7 formed from sodium hydrogen phosphate Na2HPO4 as a result of thermal conversion had a significant effect on sintering mechanism and the microstructure of the ceramics. A ceramics with a low sintering temperature based on β-calcium pyrophosphate β-Ca2P2O7 was obtained for the first time from a powder system, upon preparation of which under mechanical activation conditions homogenization of components and synthesis of the main crystal phase precursor were combined. [ABSTRACT FROM AUTHOR]

Calcium phosphate ceramics in the Ca2P2O7–Ca(PO3)2 system was obtained by annealing of hardened samples formed from highly loaded suspensions (HLS). HLSs included water and a homogenized powder mixture of calcium citrate tetrahydrate Ca3(C6H5O7)2 ⋅ 4H2O and monocalcium phosphate monohydrate Ca(H2PO4)2 ⋅ H2O. The latter was taken in the amount providing the molar ratio of Ca/P = 1 in the powder mixture, as well as at a molar ratio of Ca/P < 1 so that the excess of monocalcium phosphate monohydrate Ca(H2PO4)2 ⋅ H2O provided the formation of the calcium polyphosphate Ca(PO3)2 phase upon annealing. The samples were molded by extrusion of the HLS through a die with a diameter of 2 mm by sandwiching powder cords. After hardening and drying, the phase composition of all obtained samples included brushite CaHPO4 ⋅ 2H2O, monetite CaHPO4, monocalcium phosphate monohydrate Ca(H2PO4)2 · H2O, and octacalcium phosphate Ca8(HPO4)2(PO4)4H2O. According to the XRD data, the phase composition of all ceramic samples after annealing in a range of 800–1000°C included calcium β-pyrophosphate β-Ca2P2O7, and a ceramic sample obtained from a powder mixture with the highest excess of monocalcium phosphate monohydrate Ca(H2PO4)2 · H2O additionally included tromelite Ca4P6O19. Hardening HLSs containing water and a homogenized powder mixture of calcium citrate Ca3(C6H5O7)2 · 4H2O and monocalcium phosphate monohydrate Ca(H2PO4)2 · H2O can be used for layer-by-layer extrusion molding. The resulting calcium phosphate ceramics with lowered sintering temperature can be used for the design of a resorbable matrices of tissue engineering constructs. [ABSTRACT FROM AUTHOR]

In the present study, silk sericin–monetite microcomposites (SS–MM) were prepared using a simple and cost-effective method. Hemolytic assay was performed to determine the blood compatibility of SS–MM. MTT assay was carried out using MG-63 osteoblasts, to determine the cytocompatibility and proliferative efficacy of SS–MM. Alkaline phosphatase activity was studied to examine the osteogenic potency of the prepared microcomposites. The results obtained showed that the SS–MM can be effectively used as a bone graft for tissue engineering applications. [ABSTRACT FROM AUTHOR]

Calcium phosphate‐based biomaterials are extensively used for bone replacement and regeneration in orthopedic, dental, and maxillofacial surgical applications. The injury induced by surgical implantation of bone replacement graft materials initiates a cascade of host responses, starting with blood–biomaterial contact, protein adsorption on the material surface, blood coagulation, and leukocyte responses. During the initial acute inflammatory response, polymorphonuclear neutrophils (PMNs) and monocytes, abundant circulating leukocytes of the myeloid lineage, are recruited to the site of inflammation. In addition to responding to pathogenic challenges, these cells respond to particulate substances within the body including crystals of monosodium urate (MSU). Host responses toward grafts impact short‐ and long‐term success in tissue engineering and regenerative applications. Although multinucleated osteoclasts, formed by monocyte/macrophage fusion, are generally thought to be responsible for resorption of implant biomaterials, the ability of different biomaterials to trigger PMNs, which are invariably present at the early stages after implant surgery, and are abundant in the oral cavity, has never been tested. In this article, we present analysis of the response of human blood‐derived PMNs and monocytes toward brushite, monetite, and calcium polyphosphate (CPP) biomaterial substrates and compare this to the response to MSU crystals, the latter serving as a positive control. Employing multicolor flow cytometry to look at PMN and monocyte cell surface markers of activation to gauge the response to different biomaterials, we found that both types of myeloid cells are highly activated after exposure to brushite, monetite, and MSU but not CPP. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:253–262, 2020. [ABSTRACT FROM AUTHOR]

Absract: —On the basis of calcium phosphate compositions with a 30% polyvinyl alcohol content, three-dimensional mockups have been obtained using 3D bioprinting. It is shown that at a content of 7–14% of the polymer, calcium phosphate compositions are well extruded and exhibit the strength after hardening up to 4 MPa. Heating compositions Ca10(PO4)6 (OH)2/α-Ca3(PO4)2 up to 900°С in the presence of CaHPO4 promotes phase transformations mainly into β-Ca3(PO4)2 and β-Ca2P2O7. [ABSTRACT FROM AUTHOR]

The effect of phase composition, concentration of calcium phosphates suspensions and polymer binder on the physicochemical properties of calcium phosphate cements is found. It has been established that the introduction of monetite and polymers (polyvinyl alcohol, polyethylene glycol) in the composition of calcium phosphate cements makes it possible to increase their static strength up to 7,1 MPa varying the setting time from 1 min to 1,5 h.

Dicalcium phosphate was prepared by ethylenediaminetetraacetic acid as a calcium chelating agent, and further explored to remove the fluoride ions from aqueous solution. The as-prepared samples main existed in the monetite phase from the result of XRD. The dried sample consisted of small nanoparticles and displayed irregular particles with a size of ca. 3 μm due to the agglomeration. The fluoride removal ability was evaluated by batch adsorption experiments. The as-prepared adsorbent exhibited the enhanced fluoride removal behaviour with the maximum adsorption capacity of 66.72 mg/g from the Langmuir isotherm model, which was higher than that of other previously reported calcium phosphate. The adsorbent could be utilized in the wide pH range of 3–10. The adsorption kinetics could be better described by the pseudo-second-order model than first-second-order model. The co-existing anions had a negligible influence on the fluoride adsorption. The investigation of adsorption mechanism suggested that the chemical reaction and/or dissolution – precipitation mechanism should be dominant in the fluoride adsorption process, accompanying with electronic interaction and ions exchange, which enhanced the fluoride removal performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A nanocrystalline hydroxyapatite precipitated from the hydrothermal condition. • The hydrothermal method provides hexagonal and monoclinic hydroxyapatite. • Low temperature hydrothermal method provides high quantity of monoclinic hydroxyapatite. • The thermal stability of hexagonal and monoclinic hydroxyapatite hydroxyapatite was achieved during hydrothermal synthesis. This paper addresses the powder synthesis of nanocrystalline hydroxyapatite (HA) in a hydrothermal autoclave reactor using deionized water and the chemical reactants Ca(NO3)2 and (NH4)2HPO4 at varying pH values (7–11) and temperatures ranging from 50 to 130 °C. Analysis of the synthesized powder products included XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), SEM/EDX (scanning electron microscopy), and TG/DTG (thermogravimetry). Hexagonal and monoclinic hydroxyapatite crystallized mostly after 24-h hydrothermal processing at different initial pH values and temperatures (50–130 °C). When the temperature rose from 50 to 110 °C at a fixed pH of 10, the hexagonal phase became more prevalent while the monoclinic phase decreased proportionally. The monoclinic phase crystallite size reduced from 231.08 to 31.51 nm. Despite a constant temperature of 80 °C, pH levels ranging from 7 to 11 revealed substantial hexagonal and monoclinic hydroxyapatite with minimal monetite and brushite. FTIR spectroscopy confirmed the functional groups associated with hydroxyapatite spectra. The SEM method also revealed HA powder with spherules and anhedral agglomerates having Ca/P ratios (1.1–2.15). TG/DTG results confirmed that hydrothermal-derived HA nanosized powders are thermally stable microstructures for biomedical applications. [ABSTRACT FROM AUTHOR]

Abstract Background In vitro cell testing of degradable bioceramics such as brushite or monetite is often challenging due to the ion release into or adsorption from the culture medium. These ionic changes are then mostly responsible for cell proliferation and activity, which prohibits the investigation of effects originating from surface topography or further material modifications. Methods Here, we aimed to solve this problem by developing a pre-conditioning regime following the repeated immersion of brushite and monetite samples in various Ca2+, Mg2+ and PO4 3− containing electrolytes, followed by studying ion adsorption / release as well as changes in phase composition and in vitro cytocompatibility with MG63 cells. Results The results demonstrated that by using DMEM cell culture medium in a ratio of 10 ml/sample was sufficient to minimize changes of ionic composition after 7 d with a daily change of the medium. This leads to changes of the surface composition with dissolution of the brushite phase. In turn, this also positively influences the in vitro cytocompatibility with a 2–3 fold higher cell number and cell activity on the DMEM pretreated surfaces. Conclusions Controlled sample washing prior to cell testing using DMEM medium seems to be a valuable procedure not only to stabilize the pH during cell culture but also to maintain ion concentrations within a cell friendly range.

Zinc and its alloys seem to be promising candidates for biodegradable applications. Those materials are often modified by other elements or compounds in order to enhance their properties. The combination of zinc and apatites is challenging for several reasons. However, the advantages connected with the biological aspects suggest the need for further research into such materials. In this study, three zinc-based composites with 4 and 8 wt. % of nanohydroxyapatite or nanomonetite (Zn-4MO, Zn-4HA, Zn-8HA) were prepared by sintering and subsequent extrusion. Materials prepared in this way were characterized from the microstructural, mechanical and corrosion point of view. The obtained results showed a significant influence of particle character (amount and morphology) on the strength and ductility of the prepared materials. In case of Zn-4MO, the presence of monetite significantly increased the ductility compared with the other materials. In addition, the increment of the degradation rate caused by the presence of monetite was observed as well. All obtained results pointed out to significant advantages of monetite for the preparation of Zn-apatite composites compared with hydroxyapatite.