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In order to study the effect of MgO on the microstructure and macroscopic thermos-physical properties of calcium silicate melt, quantitative analysis of the various silicon-oxygen Qi species in magnesium-calcium silicate glasses and melts at a constant alkalinity has been performed by in-situ high temperature Raman spectroscopy, 29Si MAS NMR and DFT (Density Functional Theory) calculation. Several cluster models, probably existed in magnesium-calcium silicate glasses and melts, modified by Ca2+ or Mg2+ have been designed, their Raman vibrational modes and scattering activities were thus simulated and calculated. A function correlating the wavenumbers of Si-Onb (non-bridge oxygen) of various SiOTs (silicon-oxygen tetrahedrons) with their RSCS (Raman scattering cross sections) was constructed and used to calibrate the experimental Raman spectra. The abundance of each primary Qi species of various magnesium-calcium silicate glasses can be composed by all the deconvoluted hyperfine peaks within the same Qi species. The quantitative description for glasses was proven to be consistent with the result from 29Si MAS NMR. Thus, Qi species distributions for melts were also quantitatively derived. It demonstrated that the abundances of Q1 and Q3 species increased while Q2 species decreased with the increasing replacing amount of MgO. The relationship between the viscosity and Qi species distributions as well as different cations has been investigated and correlated. Q3 species was predominantly responsible for the contribution of viscosity of melt.

Electrical conductivity and structure of the CaO-SiO2-based mold flux melts with various Al2O3 contents were investigated. The results show that the electrical conductivity increases with the addition of Al2O3 from 2 wt% to 4 wt%, but decreases with the further increase of Al2O3 from 4 wt% to 8 wt%. Correspondingly, the apparent activation energy reduces firstly from 55.12 ± 1.20 kJ mol to 41.09± 0.38 kJ mol, and then increases from 41.09 ± 0.38 kJ mol to 98.99 ± 1.42 kJ mol. The structure analyses suggest that complex structural units, such as Si-O-Al, Al-O0, Si-O-Si and Q3(Si), reduce first, but increase with the further addition of Al2O3. Conversely, these simple structural units, such as Al-O-, Q0(Si), Q1(Si) and Q2(Si) vary in the opposite way with the change of Al2O3 content. From the variations of electrical conductivity, activation energy and structural units, it can be found that when Al2O3 works as network breaker to simplify the melt structure, the energy barrier for transportation of conducting ions/ionic reduce, which results in the increase of electrical conductivity; while when Al2O3 becomes into network former, the conductivity increases, correspondingly.

A type of strontium and amorphous calcium phosphate dipped premixed injectable tricalcium silicate-based dental root canal sealer was developed as the following protocols. A powder mixture containing tricalcium silicate, strontium carbonate (6, 8, 10, and 12 wt%), zirconia (20 wt%), calcium chloride (6 wt%), and amorphous calcium phosphate (ACP) (5 wt%) was mixed with liquid polyethylene glycol 400 (PEG 400) at a liquid-to-powder ratio of 0.5 mL/g and mechanically ground using a planetary ball to obtain the premixed injectable calcium silicate-based sealer. The sealer’s physicochemical property and cytocompatibility were evaluated in vitro. Quantitative data were expressed as mean ± standard deviation, and Student's t-test or a one-way analysis of variance (ANOVA) test were carried out at significant differences with P

In this study, porous calcium silicate (CS) ceramics with oriented arrangement of lamellar macropore structure were prepared by directional freeze casting method. The lamellar macropores were connected by the micropores on the pore wall, which had good pore interconnectivity. The effects of solid loading of the slurry, freezing temperature, sintering additive content, and sintering temperature on the microstructures and compressive strength of the synthesized porous materials were investigated systematically. The results showed that with the increase of solid loading (≤20 vol%) and sintering additive content, the sizes of lamellar pores and pore walls increased gradually, the open porosity decreased and the compressive strength increased. The sintering temperature had little effect on the pore size of the ceramics, but increasing the sintering temperature (≤1050 °C) promoted the densification of the pore wall, reduced the porosity, and improved the strength. The decrease of freezing temperature had little effect on porosity, but it reduced the size of lamellar pore and pore wall, so as to improve the strength. Finally, porous CS ceramics with lamellar macropores of about 300–600 μm and 2–10 μm micropores on the pore wall were obtained. The porous CS ceramics had high pore interconnectivity, an open porosity of 66.25% and a compressive strength of 5.47 MPa, which was expected to be used in bone tissue engineering.

The scaffold of bone repair needs a variety of material combinations to meet its intended performance; a typical single material such as zirconia has excellent mechanical properties, while hydroxyapatite and calcium silicate are bioactive materials with different degradation rates. In this paper, porous zirconia scaffolds were fabricated using 3D printing technology. The surface of the scaffold was coated by dipping with different contents of calcium silicate and hydroxyapatite to improve the biological activity and mechanical properties. Mechanical tests show that the coating material can effectively fill the pores of the porous scaffold, increasing its compressive strength by an average of 55%. The simulated body fluid (SBF) test showed that the higher calcium silicate in the coating increased the degradation rate. Cell experiments showed that the coated scaffolds exhibited good cytocompatibility and were beneficial to the proliferation and differentiation of cells. In conclusion, coated scaffolds have potential applications in the field of bone repair.

One-dimensional conductive materials are of great significance to the construction of conductive network in the polymer matrix due to their large aspect ratio. In this work, a nickel-plated rod-like calcium silicate composite (Ni@RL-CS) with unique vermicular structure was successfully fabricated by an electroless plating method. The structure and property of as-prepared Ni@RL-CS were characterized, and its electromagnetic shielding ability was evaluated through mixing with thermoplastic polyurethane (TPU). Results indicate that the Ni@RL-CS shows good electrical conductivity, magnetic property and strong dielectric loss ability. The Ni@RL-CS with a one-dimensional vermicular structure is easier to construct a continuous conductive network in TPU matrix, which greatly improves the electromagnetic shielding effectiveness of the TPU resin. TPU/Ni@RL-CS binary composite with 20 vol% Ni@RL-CS achieves ultrahigh specific EMI SE/thickness of 92.6 dB/mm in the frequency of X-band. By further hybridizing Ni@RL-CS with GNPs, the TPU/Ni@RL-CS/GNPs trinary composite exhibits excellent electromagnetic shielding performance. When the contents of Ni@RL-CS and GNPs are 10 vol% and 1.5 vol%, respectively, the specific EMI SE/thickness of the corresponding trinary composite reaches 74.6 dB/mm in the X-band owe to the dense conductive network, which is 56.5% higher than that of the binary TPU/Ni@RL-CS composite with the same content of 10 vol% Ni@RL-CS.. The synergistic effects of dielectric loss, magnetic loss, and the interfacial polarization loss are the main shielding mechanism. This work provides a strategy to prepare a functional filler based on an insulating inorganic material for electromagnetic shielding. The as-prepared Ni@RL-CS with the unique vermicular structure and outstanding electromagnetic shielding performance can serves as a functional filler to modify polymers for electromagnetic shielding applications.

β-tricalcium phosphate bioceramics suffer from a drawback of poor mechanical strength and a scarcity of capacity to regulate biological performances. In the current study, the overall performances of β-tricalcium phosphate (TCP) bioceramics were improved by incorporating calcium silicate (CS) and magnesium-strontium phosphate (MSP). During the sintering process, the MSP stabilized the β phase of TCP, and the formation of MSP melt ensured effective liquid-sintering of TCP, thus conducing to lower porosity of TCP/MSP and TCP/CS/MSP bioceramics. In comparison with the TCP bioceramics, the TCP/CS and TCP/MSP bioceramics showed lower compressive strength, while the TCP/CS/MSP bioceramics attained noticeably higher compressive strength. Due to the sustained release of therapeutical ions, the TCP/CS bioceramics enhanced in vitro early-stage osteoblastic differentiation, but compromised cell proliferation; both the TCP/MSP and TCP/CS/MSP bioceramics enhanced cell proliferation and osteoblastic differentiation, and restrained osteoclastic activities. Collectively, the TCP/CS/MSP bioceramics with optimal overall performances are promising for efficaciously treating the defects of osteoporotic bone.

This paper reports on the synthesis and characterization of original sodium calcium silicate glass, with CaF2 as a nucleating agent, along with the successful transformation of the as-made matrix into glass-ceramic. Characteristic temperatures of thermal events were investigated by Differential Thermal Analysis. Volumetric density, refractive index, molar volume, and electronic polarizability of the newly developed glasses were determined and discussed as a function of Ca(O/F2) and Na2O content, fixing glass former SiO2 at 50 mol%. Transmittance and optical band gap energy were evaluated. Network structure was studied through Raman spectroscopy and X-Ray diffraction. Moreover, Eu3+ was used as a local structural probe in equivalent Eu2O3-doped samples. Luminescence properties (emission spectra and transition lifetimes) allowed us to investigate the local environment of precursor glass and glass-ceramic. Calcium fluoride nanostructured glass-ceramic, with 20 nm-sized crystals, was obtained with significant transparency (60–70% in VIS region). The refractive index of synthesized glasses was too close to that of precepted crystals, which is the requisite for high transmittance. The decay time of Eu3+ ions embedded into the matrix has shown that the glass-ceramics environment's phonon energy is lower than in as-made glass, making this matrix an excellent candidate for photonics applications.

Chemotherapic cancer treatment has suffered from side effects and poor target specificity. pH-triggered drug delivery systems offer the opportunity to better deliver anticancer drugs to cancer cells in a more controllable manner. Herein, we reported a facile method to synthesize Mg-doped Ca2SiO4 (CaMgSiO4) nanospheres with highly porous structures as pH-responsive drug delivery. Material characterizations confirmed the uniform Mg doping within calcium silicates. After the Mg doping, the surface area of calcium silicates increased from 185.68 m2/g to 212.71 m2/g. When incorporated with PEG surface coating, the porous CaMgSiO4 nanoparticles displayed over 50% increased doxorubicin (DOX) loading capacity compared with Ca2SiO4 nanoparticles. The pH-triggered DOX release behaviors and cytotoxicity of porous CaMgSiO4 nanoparticles were investigated. As a result, porous CaMgSiO4 nanoparticles were highly sensitive to pH stimulus and exhibited high biocompatibility and strong cancer cell killing effect (over 75%).

Samarium doped calcium silicates ( C a 2 − x S i O 4 : x S m 3 + , (x(%) = 0.25, 0.50, 0.75, 1.00) are synthesized using cost effective natural resources such as rice husk ash and egg shell powder through solid-state reaction method. The structural, optical, and photoluminescent properties of the as-prepared samples are reported. X-ray diffraction and Rietveld refinement results confirm that monoclinic- C a 2 S i O 4 phase is stabilized at room temperature in agro-food waste derived phosphors. Differential thermal analysis data provides information about the phase transformations. Scanning electron microscope images show that the synthesized samples have spherical morphology. C a 2 S i O 4 related vibrational bands appear in the Fourier transform infrared spectrum. Optical band gap of these phosphors is found to lie in the range 3.56–3.67 eV. Agro-food wastes inherently contain titanium in trace amounts thus, the photoluminescence emission spectrum consists of bands linked to both samarium and titanium ions. Presence of titanium makes these phosphors inherently luminescent. CIE co-ordinates of these phosphors lie in the bluish-green region. These results suggest that agro-food wastes have excellent potential of being used as precursors for synthesizing visible light emitting phosphors. Moreover, present study paves the way for effectively utilizing agro-food wastes for synthesizing environment friendly and cost-effective phosphors.

The mineral formation-transition mechanism, microstructure morphology evolution, pulverization property and chemical reactivity of calcium sulpho-aluminate with sodium dopant are systematically studied with the molar ratio of CaO to Al2O3 is 0.8, the molar ratio of CaO to SiO2 is 1.5, the mass ratio of Al2O3 to SiO2 is 2.0, and the SO3 accounts for 4%. The results show that sodium dopant could promote 3CaO·3Al2O3·CaSO4, CaO·2Al2O3 and 2CaO·Al2O3·SiO2 transform into 2CaO·SiO2, CaO·Al2O3, 12CaO·7Al2O3 and 2Na2O·3CaO·5Al2O3, and it also can decrease the decomposition temperature of reactive materials and the initial phases formation temperature significantly. Sodium diffusion can destroy the clear grain boundary of calcium aluminate and calcium silicate phases, change the macro-microstructure morphology, improve the crystalline degree of the samples, and then improve the pulverization and alumina leaching property. However, excessive sodium dopant can decrease the melting temperature, inhibit the transformation process of 2CaO·SiO2 from β to γ, and then deteriorate the pulverization property significantly again.

In this study, porous calcium silicate (CaSiO3) scaffolds were prepared by 3D gel-printing (3DGP) method and Fe3O4 water-based magnetic fluids (WMFs) were prepared by phacoemulsification compound chemical coprecipitation method. Fe3O4 WMFs were coated on CaSiO3 scaffolds surface to prepare Fe3O4/CaSiO3 composite scaffolds. The effect of WMFs with different Fe3O4 concentrations on porous CaSiO3 scaffolds was studied. The composition and morphological characteristics of porous scaffolds were analyzed by using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis. The magnetic properties were tested by vibrating sample magnetometer (VSM). The stability of Fe3O4 WMFs coatings and the degradability of composite scaffolds were tested by immersing them in simulated body fluid (SBF). The results show that when Fe3O4 concentration was 5.4% (w/v), the composite scaffolds had the highest saturation magnetization of 69.6 emu/g and the best stability in dynamic SBF. It is obviously that Fe3O4 WMFs coatings can be used for bone tissue engineering scaffolds repairing.

Calcium silicate (CS) composite bone tissue engineering scaffolds were three-dimensionally printed using titanium metallic powders as the second strengthening phase for overcoming the inherent brittleness and fast degradability. In order to promote the sintering process of all composite scaffolds, mesoporous structure was further introduced into sol-gel-derived CS powders obtaining mesoporous CS (MCS) with larger surface area. The influences of mesoporous structure, sintering temperature and Ti content have been investigated through comparisons of the final scaffold composition, microstructure, compressive strength and in vitro stability. Results showed that CS matrix materials reacted with Ti could form less degradable CaTiO3 and TiC ceramic phases under 1200 °C sintering. The MCS-Ti scaffolds presented significantly improved density and homogeneity compared to CS-Ti. Therefore, MCS-Ti3 scaffolds with the highest 30% Ti addition, possessed the biggest compressive strength of 4.11 ± 0.39 MPa. Moreover, in vitro degradation analyzations demonstrated that MCS-Ti scaffolds enhanced ability of control over the weight losses and pH values of surrounding medium, indicating promising use as an alternative composite for bone repair.

Bioceramic materials currently applied in bone repairing mainly base on calcium phosphate compounds like hydroxyapatite (HA), however, issues including slow degradation rate and insufficient bioactivity limit their efficiency in promoting bone regeneration. Calcium silicate (CS) is a promising alternative for the purpose thanks to its degradability and bioactive Si4+ release ability, while its fast degradation rate will cause pH problem and does not match the rhythm of osteogenesis. Herein, 3D composite bioceramic scaffolds were fabricated by blending different weight fractions (1:0, 3:1, 1:1, 1:3 or 0:1) of CS nanofibers (CSNFs) and HA nanowires (HANWs) via steps of fiber-dispersing, freeze-drying and sintering. With subsequent polymer coating, the porous structure and mechanical properties of the CSNF/HANW scaffolds were improved and scaffold performances were further regulated in dependence on the hydrophobicity/hydrophilicity and degradation rates of the polymers. Poly( l -lactide) (PLLA), poly(lactide-co-caprolactone) (PLCL) and gelatin were applied as the polymer coating. It was found that PLLA- and PLCL-coating would slow down the scaffold degradation and ion release rate compared to the gelatin-coating, while the increasing fraction of CSNFs would accelerate these events to increase medium pH due to the alkalinity of the bioceramic material. Finally, proliferation and osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs) achieved desirable outcomes on gelatin-coated CSNF/HANW scaffolds with their fractions of 1:1 and 1:3, strongly suggesting the potential of these scaffolds for bone regeneration.

To assess the impact of changes in slag type on the degradation of refractory linings of secondary copper smelters, the degradation behavior of direct-bonded and fused grain magnesia–chromite refractories in ZnO-containing ferrous calcium silicate slags was studied via dynamic refractory finger and static refractory crucible tests at 1200 °C under Ar atmosphere. The effect of ZnO level in the slag and refractory type on the degradation behavior was determined. A combination of microstructural and compositional characterizations of tested refractories, and thermodynamic calculations leads to comprehensive understanding of the degradation mechanism of the refractories. Based on the degradation mechanism, conclusions can be given about the prediction of lifetime of refractory lining when the slag type changes from fayalite-based to ferrous calcium silicate-based slags for secondary copper smelting.

Titanium and its alloys are widely used for medical implant applications, but their corrosion in the physiological environment leads to the discharge of metal ions, which can trigger severe health issues. In the present study, calcium silicate reinforced hydroxyapatite (HA-CS) coatings were deposited on the Ti6Al4V substrate by using atmospheric plasma spray (APS) process with an aim to improve the corrosion resistance and bioactivity. The coatings were prepared by varying the weight percentage (wt %) of calcium silicate (CS) reinforcement in hydroxyapatite (HA) as Ha/x CS (x = 0, 10, 20 wt %). The SEM analysis of the pure HA coating revealed the presence of surface microcracks, whereas HA-CS coatings displayed the crack-free surface morphology. The corrosion investigation revealed that with the progressive increment of CS content in HA coating, the corrosion resistance of HA-CS coatings improved. In addition, surface roughness, porosity, microhardness and crystallinity increased with the increase of CS content in HA. The findings of this study indicate that the development of plasma sprayed HA-CS coatings is a promising approach to improve the performance of Ti6Al4V alloy for medical implant applications.

The cancerous bone may be treated using magnetite nanoparticles (MNPs) coupled with hyperthermia treatment technology. During the last three decades, calcium-silicate (CS) based bioceramics have been investigated as a proper choice due to their bioactivity, biocompatibility, magnetization property, and ability to form suitable apatite for hard tissue engineering approaches. For this purpose, three-dimensional bio-nanocomposite scaffolds utilizing bioactive wollastonite (WS) and bioglass (BG) as composed based materials with 0 wt% (S1), 5 wt% (S2), 10 wt% (S3), and 15 wt% (S4) of Zr–Fe3O4 are considered in this study. These materials with two various space-agents such as sodium chloride (NaCl) and sodium bicarbonate (NaHCO3) particles containing ball mill with high energy and pressing under 150 MPa, and sintered at 850 °C are analyzed. Additionally, X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating-sample magnetometer (VSM), and mechanical tests include of toughness and compressive strength are investigated. The powder's and scaffold's crystals size are measured between 30 and 50 nm, and the pores and porosity size are measured from 70 to 180 μm and 25%–40%. The VSM curves illustrate that the zirconium-ferrite has a soft magnetic property, which is easily magnetized by applying a small amount of magnetic field, and it rapidly loses its magnetic moment by cutting off the field. The low coercive force, as well as high magnetic saturation with low residue, are represented for the S2 and S3. The obtained outcomes indicate that the best amounts of mechanical properties amongst the specimens are related to the specimen with 15 wt%, 7.9 ± 1 MPa of compressive strength, and 203.3 ± 10 MPa of elastic modulus. Likewise, the biological assessment shows that the sample containing 10 wt% MNPs provides a better apatite creation on porous scaffolds after 28 days. The gained outcomes represent that those specimens containing 10 and 15 wt% MNPs provide proper biological and mechanical replies.

Samarium (Sm3+) doped sodium calcium silicate (Na2CaSiO4: NCS) phosphors have been synthesized by employing a sol-gel technique. The structural, morphological, excitation and emission spectral studies have been carried out for the as-prepared phosphors. The phase purity in synthesized NCS phosphor with cubic structure has been confirmed by X-ray diffraction (XRD) pattern. The scanning electron microscopic images depict the irregular morphology and non-uniform microcrystalline particles in synthesized phosphor. The excitation spectra of NCS: Sm3+ phosphors disclose strong absorption in UV (ultraviolet), n-UV (near UV) and blue spectral regions. The emission spectra recorded under 402 nm excitation exhibit peaks at 565, 602 and 649 nm attributed to characteristic 4f-4f transitions of Sm3+ ions. The Sm3+ concentration optimized for NCS host as 1.0 mol%, and concentration quenching phenomenon has been discussed in detail. The chromaticity coordinates (0.579, 0.419) for optimized NCS: Sm3+ phosphor lie in the pure orange region. The temperature-dependent photoluminescence studies demonstrate that luminescence intensity even at 423 and 463 K persists up to 85.4 and 79.6% of the intensity at room temperature, respectively. Above mentioned results substantiate the potentiality of NCS: Sm3+ phosphor to use as a thermally stable orange emitting component in photonic devices.

Calcium silicate (CS) bioceramic is a promising candidate in bone tissue engineering due to its excellent bioactivity and biodegradability. However, the deficient mechanical properties make it challengeable in hard bone tissue replacement. In this work, high-strength β-CS bioceramics were prepared with low melting-point B2O3–SiO2 sintering additives using liquid phase sintering mechanism via a versatile milling-pressing-pressureless sintering route. The results showed that the addition of B2O3–SiO2 could significantly promote densification and induce the in-situ growth of β-CS rod-like grains. β-CS ceramics with 5 wt% addition of B2O3/SiO2 with mass ratio of 92.5:7.5 sintered at 1000 °C for 2 h exhibited a relatively high flexural strength of 228.14 MPa, increased by 340% compared to that of pure β-CS ceramic (52.08 MPa) prepared under the same conditions. The elevated strength fully qualified the strength requirement of cortical bone (135–193 MPa), indicating β-CS ceramic reinforced with B2O3–SiO2 additives had great potential in load-bearing bone repair.

Bioceramics have been widely used for many years to restore and replace hard tissues including bones, teeth and mineralized matrices such as calcified cartilages at osteochondral interfaces, mainly because of their physicochemical similarity with these tissues. Calcium silicate based bioceramics have been shown to possess high bioactivity due to having high apatite-forming ability and stimulating cell proliferation, as well as biodegradability at rates appropriate to hard tissue regeneration. The outstanding biological properties of these ceramics have made them the most studied hard tissue engineering biomaterials along with calcium phosphates and bioactive glasses. Baghdadite is a calcium silicate containing zirconium ions which promotes the proliferation and differentiation of human osteoblasts and consequently increases mineral metabolism and ossification. Recently, it has attracted considerable attention in academic community and widely studied in the form of porous scaffolds, coatings, bone cement and void fillers, microspheres and nanoparticles mostly in orthopedic, dental and maxillofacial applications. This review paper is aimed to summarize and discuss the most relevant studies on the mechanical properties, apatite formation ability, dissolution behavior, and in vitro and in vivo biological properties of baghdadite as a biomaterial for hard tissue regeneration applications.

The formation and transition of calcium aluminate and calcium silicate compounds from pre-synthesized mullite in low-calcium system were systematically studied by solid-state reaction at 1350–1500 °C using XRF, XRD, FTIR, SEM and PSD methods. Ca3Al2O6, Ca12Al14O33, CaAl2O4, Ca2SiO4 and Ca2Al2SiO7 can form via direct reaction of mullite with CaO at the beginning of the reactions, then Ca12Al14O33 and Ca3Al2O6 react with mullite to form CaAl2O4 and Ca2SiO4, and finally Ca2Al2SiO7 reacts with CaO to generate Ca2SiO4 and calcium aluminate compounds as the sintering process proceeds. Elevating the sintering temperature is in favor of the formation of Ca12Al14O33, Ca3Al2O6 and Ca2Al2SiO7 at the initial reaction stage, but Ca2Al2SiO7 cannot totally transform to calcium silicate and calcium aluminate compounds in the low-calcium system, which deteriorates the pulverization performance of the final products. Increasing the calcium dosage accelerates the transformation of Ca2Al2SiO7 to Ca12Al14O33, CaAl2O4 and Ca2SiO4, which enhances the pulverization performance. If the CaO/Al2O3 molar ratio exceeds 1.4, Ca3Al2O6 will generate by the reactions of pre-formed CaAl2O4 and Ca12Al14O33 with excessive CaO.

Ceramic layers based on calcium silicate non-substituted and substituted by Zn with different thickness, were developed by immersing porous Y-TZP disks into SiO2–CaO–ZnO–P2O5 glass suspensions with ZnO contents in the range of 0–20 mol%. The effect of the disk surface porosity and the slip solid loading on the formation of the dip coated layer was investigated. Special emphasis was given to the ZnO content of the dip coating slurries and its influence on the thickness and composition of the sintered layer. The greater chemical stability of the 20 mol% ZnO-substituted glass powder during aqueous colloidal processing resulted in slips with low viscosity values; whereas the high dissolution rate of the glass having 10 mol% ZnO significantly increased the slip viscosity. The liquid entrainment mechanism at the initial stage was accelerated either by using 10 mol% ZnO-substituted glass slips or by increasing the slip solid loading. The casting rate for longer immersion times markedly increased by increasing the surface porosity of Y-TZP disks. Sintered layers with thickness ~30–70% lower were produced using the glass dip coating slip with 20 mol% ZnO in comparison to 10 mol% ZnO. The main crystalline phase of the coated sintered layers was Ca3Si3O9, Ca2ZnSi2O7 and ZnSiO4 for the glasses with 0, 10 and 20 mol% ZnO, respectively.

Porous CaSiO3 composite scaffolds with different dopants, such as MgSiO3, MgCl2 and CaSO4, were successfully prepared by 3D gel-printing (3DGP). (m, n) is proposed to describe the filament geometry features. The results show that doping can improve the strength of porous composite scaffolds and MgCl2-doped composite scaffolds had the highest modulus of elasticity of 1241 MPa. The shrinkage rate range of the composite scaffolds was 11.44–13.16%, and their porosity was all about 60%. When porous composite scaffolds were soaked in SBF for 28 days at 37°С, the degradation rate was 2.7% (pure), 0.3% (MgSiO3), 0.2% (MgCl2), 5.27% (CaSO4), respectively. It explains that MgSiO3 and MgCl2 inhibited the in vitro degradation of CaSiO3, while CaSO4 promoted. It is obviously that doped MgCl2 can improve the mechanical properties of porous scaffolds, and doped CaSO4 can improve the degradation of scaffolds, which play an important role in bone repair engineering.

The goal of this work is to develop multilayer scaffolds with a high durability core and bioactive external layers. Different ceramics were analysed by Scanning Electron Microscope fitted with Energy-Dispersive X-Ray Spectroscopy, X-Ray Diffraction and they were subjected to in vitro testing using simulated body fluid. A non-bioactive porous ceramic scaffold, composed fundamentally of calcium pyrophosphate and tricalcium phosphate, constituted the core of the final multilayer ceramic. Otherwise, a highly bioactive ceramic, composed fundamentally of a major amorphous calcium silicate phase with traces of Zn in its composition, constituted the external layers of the final multilayer ceramic. When the multilayer ceramic was analysed, the mineralogical phases changed compared with core ceramic individually, and it was demonstrated that bioactive external layers provided this capacity to the core ceramic, constituted by a material that was initially non-bioactive.

Ceramic nanofibers prepared via precursor sol-gel electrospinning and calcination are widely reported, but few reports address the possible formation of core-shell structured ceramic nanofibers. In this study, core-shell structured calcium silicate (CS) nanofibers were obtained by changing the compositions of the precursor sol-gel solutions and the calcination temperatures to determine the mechanism leading to the core-shell structure during preparation. The sol-gel solutions used to produce CS nanofibers were prepared from calcium nitrate and tetraethyl orthosilicate, and it was found that CS nanofibers prepared from sol-gel solutions with a Ca/Si molar ratio of less than 1:1 displayed a distinguishable core-shell structure with calcination temperatures higher than 1000 °C. The fiber shell was identified as mainly silica with sparse calcium, and the fiber core was composed predominantly of calcium silicate. A tubular morphology was clearly observed with preferential degradation of the fiber core. The fiber shell became thinner or it disappeared if the precursor sol-gel solutions had Ca/Si molar ratios higher than 1:1 or if the applied calcination temperature was less than 1000 °C. After doping the CS fibers with zinc, it was confirmed that the zinc was also predominantly located in the fiber core, similar to calcium. It was proposed that the formation of CS nanofibers with a surface silica layer resulted from the migration of Si-O-Si precursor gel particles toward the fiber surface with solvent evaporation during electrospinning and transformed into a silica shell during calcination. Thus, the calcium (or zinc) elements were enriched inside the fiber to obtain a type of heterogeneous CS nanofiber. These materials are expected to serve as good biomaterials for bone regeneration by providing sustained release of bioactive ions.

α-alumina, hydroxyapatite (HA) and bioactive glass are all promising bioceramic materials with specific properties. However, there is a limited amount of work involving their composites. Therefore, this work focuses on preparation and characterization of alumina-HA-bioactive glass composites. HA, α-alumina and bioactive glass powders were prepared through wet chemical precipitation, sol-gel and conventional melting-quenching processes, respectively. Composite pellets were formed by pressing the bioceramic powder mixture and then sintering at 1250 °C for 1 h. Chemical phase analyses proved that α-alumina, whitlockite, anorthite and sodium calcium silicate phases were found in the sintered samples. Bioceramic composite pellets exhibited pretty low compression strength (∼28.50–47.3 MPa) due to high apparent porosity (∼28–30%). Microstructure observations showed that calcium phosphate (CaP) based precipitations with different morphologies were developed on the surface of the composites depending on the immersion time in phosphate buffered saline solution. This was attributed to the favorable bioactivity behavior of the material.

In the current investigation, the microarchitecture of bio-nanocomposite scaffold, which is fabricated by natural synthetic diopside and composed of magnetite nanoparticles (MNPs), is considered. The MNPs are tested with various weight fractions (0, 5, 10, and 15 wt%) and are manufactured by the freeze-drying technique using sodium alginate as base matrix for the first time. Due to the limitation of the mechanical properties of calcium phosphates (CaPs) and bioactive glasses (BG), clinical usage of calcium silicate ceramics (CSC) are greatly affected. Therefore, CSCs are produced with the incorporation of metal oxides into the base binary xCaO-ySiO2, as well as the substitution of calcium ions. Furthermore, mechanical and biological properties of CSCs are enhanced, which are a result of the ability to give out bioactive ions and their distinct compositions. After that, the porous bio-nanocomposite scaffolds are investigated for biological and mechanical properties corresponding to hardness versus elastic modulus, apatite formation versus biodegradation rate, wetting properties versus roughness and electrical conductivity of the sample. Then, the composition, microstructure, and physical characteristics are also examined using different techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) which is equipped with energy-dispersive X-ray spectroscopy (EDX). The obtained outcomes show that addition of diopside bioceramic enhances the mechanical and physical properties of the samples. It is shown that the prepared porous bio-nanocomposite scaffolds, containing 10 wt% MNPs, represents a better agreement in serving as a bone graft for the cancer disease treatment and hyperthermia term. The results indicate that the specimen with 10 wt% MNPs in the bio-nanocomposite release the celecoxib drug easier, however, its has better porosity and mechanical behavior that make it suitable candidate for bone implantations.

In this work the impact of Al2O3 amount on the synthesis (200 °C; 4–8 h) of calcium aluminium silicate hydrates (CSAH) samples and their influence on the early stage hydration of calcium aluminate cement (CAC) was examined. It was found that the amount of Al2O3 plays an important role in the formation of calcium aluminate hydrates (CAH) because in the mixtures with 2.7% Al2O3 only calcium silicate hydrates (CSH) intercalated with Al3+ ions were formed. While in the mixtures with a higher amount of Al2O3 (5.3–15.4%), calcium aluminate hydrate – C3AH6, is formed under all experimental conditions. It is worth noting that the largest quantity of mentioned compound was obtained after 4 h of hydrothermal treatment, in the mixtures with 15.4% of Al2O3. It was proved that synthesized C3AH6 remain stable up to 300 °C and at higher temperature (945 °C) recrystallized to mayenite (Ca12Al14O33), which reacted with the rest part of CaO and amorphous structure compound, resulting in the formation of gehlenite (Ca2Al2SiO7). Moreover, the synthesized C3AH6 addition induced the early stage of CAC hydration. Besides, in the samples with an addition, the induction period was effectively shortened: in a case of pure CAC (G70) paste, hydration takes about 6–6.5 h, while with addition – only 2–2.5 h. The synthesized and calcinated compounds was characterized by using XRD and STA analysis.

In this work the effect of Na 2 O on the synthesis of α-C 2 S hydrate (2CaO·SiO 2 ·H 2 O), named as α-C 2 SH, with different mineral composition and the stability of intermediate and final products were investigated. It is worth noting that new results was discovered by evaluating the mineral composition of hydrothermally synthesized α-C 2 SH samples (200 °C; 2–72 h). It was found that Na 2 O additive significantly influenced the formation and stability of intermediate and final products: within 12 h of hydrothermal treatment together with α-C 2 SH a new calcium silicate hydrate phase, killalaite, was obtained in the products. Besides, the mineral composition of formed compounds slightly varied by prolonging the duration of synthesis to 24 h. For the first time it was proved that Na + ions are not incorporated into the crystal structure of the main synthesis product, α-C 2 SH. On the contrary, the mentioned ions are intercalated into the crystal structure of other calcium silicate hydrates. Moreover, the investigated alkaline additive reduced the recrystallization temperature of the synthesis products to wollastonite by 50 °C and significantly decreased the values of both specific area and total pore volume of α-C 2 SH till 8.496 m 2 /g and 0.05084 cm 3 /g, respectively. The synthetic products were characterized by XRD, DSC, SEM/EDX and N 2 adsorption analysis.

Five nanocomposite samples containing different percentages of carbonated hydroxyapatite (CHA), selenium dioxide (SeO2) and inert glass (IG) have been prepared using high-energy ball milling method with the aim of improving the in vitro bioactivity of these nanocomposites. Fourier transform infrared (FTIR) spectroscopy along with X-ray diffraction (XRD) technique was applied on both nanopowders and the sintered nanocomposites to record the structural changes and examine the resultant sintered phases. Mechanical properties were measured by ultrasonic non-destructive technique. In order to assess the bioactivity of the sintered specimens, they were soaked in simulated body fluid for 14 days and then, they were investigated by FTIR and scanning electron microscopy (SEM). Both FTIR and XRD spectra showed that the glasses encouraged the partial HA decomposition to tricalcium phosphate (TCP) and calcium silicate (CaSiO3) phases. The formation of the latter phase along with the remainder HA contents was responsible for good bioactivity and appropriate mechanical properties of the investigated nanocomposites. The successive addition of selenium dioxide to these nanocomposites led to further improvement of their bioactivity without any recorded changes in the mechanical properties. Based on the abovementioned results, the prepared nanocomposites can be used in various tissue-engineering applications.

Injectable bioactive ceramics with excellent osteogenesis play important roles in bone regeneration field. In this study, we creatively fabricated the injectable nano-structured silicon-containing hydroxyapatite (Si-HAp) microspheres in diameter of 70–100 µm via hydrothermal treatment of calcium silicate (CaSiO3) microspheres in Na3PO4 aqueous solution. The fabricated Si-HAp microspheres were constructed by nano-rods with a diameter of 100 nm and length up to 1.5 µm. Comparing with the pure HAp microspheres, the obtained nano-structured Si-HAp microspheres exhibited excellent protein loading properties and sustained protein release capacities. Most importantly, the Si-substitution could apparently enhance the proliferation, osteogenic differentiation and the genes expression of angiogenic factors of rat bone marrow mesenchymal stem cells (rBMSCs). These all indicated that the nano-structured Si-HAp microspheres fabricated via hydrothermal transformation method might be used as promising injectable bioactive biomaterials and drug deliveries for bone regeneration.

Hydroxyapatite (HA, Ca5(PO4)3OH) has been extensively used for bone implantation due to its similarity to the mineral component of bone, which makes it strongly osteoconductive. However, HA has low resorbability, and it is difficult to replace by a newly regenerated bone. Si doping can enhance the resorbability of HA by modifying its crystal structure. Here, we developed a simple thermal technique for preparing Si-doped HA from silica (SiO2) and HA precursors, both of which are inexpensive and commercially available. This method included the physical binding of SiO2 and HA particles, followed by pressing and sintering the mixture at an elevated temperature, which enhanced the atomic diffusion of Si into HA unit cells. We also evaluated the simulated body fluid (SBF) activity of the Si-doped HA prepared by this technique and showed that it significantly had higher resorbability and mineralizing potential compared to the pure HA. Our experimental design including, the individual precipitation and resorption assays enabled us to explain the mechanism behind the improved activity of Si-doped HA in SBF. This was attributed to the formation of new phases, such as β-tricalcium phosphate (β-TCP) and calcium silicate (Ca2SiO4) with higher solubility than HA on the SiO2-contating HA during the sintering stage. This can provide some guidelines for designing new calcium phosphate-based materials for hard tissue engineering applications.