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This study focuses on the relationship between porosity, surface roughness, microstructure, strength, and thermal properties, as well as their effect on the bioactivity and biodegradability of fabricated akermanite (AK; Ca 2 MgSi 2 O 7) bioceramic scaffolds. Firstly, we prepared the AK nanopowders using the mechanical activation method, mixed them with varying proportions of space-holder agent (NaCl), specifically 15, 20, 30, 40, and 50 vol%, and sintered them at 1200 °C to create porous scaffolds. We investigated the physical properties and microstructure using the Archimedes method and field emission scanning electron microscopy (FE-SEM), respectively. The mechanical properties in terms of microhardness, compressive strength, longitudinal modulus, Young's modulus, bulk modulus, and shear modulus were measured. The bioactivity and biodegradability of prepared scaffolds were assessed after soaking in simulated body fluid (SBF) for 10 days by FE-SEM and inductively coupled plasma-atomic emission spectroscopy (ICP-AES), respectively. The results revealed that porous scaffolds with suitable mechanical properties, bioactivity, and biodegradability were prepared. The porosity had a significant impact on the mechanical and biodegradability of the investigated scaffolds. It reduced mechanical properties slightly while improving bioactivity and biodegradability. The microstructure study displayed that all scaffolds formed apatite layer on their surfaces. This is because of good bioactivity and the suitable porosity level of AK. The obtained findings provide promising prospects for the future use of AK in bone tissue engineering. [ABSTRACT FROM AUTHOR]

The preparation of di-calcium magnesium silicate Ca2MgSi2O7 doped with 0.5, 1.0, 1.5, 2.0 and 2.5 mol.% of erbium (III) using a solid state reaction method is reported. An X-ray diffraction pattern obtained from the sample at optimum photoluminescence (PL) emission intensity exhibits a quite prominent resemblance with the crystallographic open database (COD) with entry 96-900-6449. This confirms the valid preparation of tetragonal akermanite with a P-4 21 m (113) space group. A 980 nm laser source is used as an excitation radiation for recording the PL emission spectra. The emission spectra exhibit two distinguished prominent peaks centered at 534 and 623 nm. These peaks are attributed to the 2H11/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of erbium (III) ions respectively. The sample with 2.0 mol.% of erbium (III) exhibits an optimum PL intensity, and beyond this the concentration quenching occurs. The thermoluminescence studies of the same sample suggest an existence of the near second order kinetics. Therefore, the sample could be a very good candidate in LED applications. [ABSTRACT FROM AUTHOR]

This study investigated the incorporation of akermanite into a polylactic acid (PLA) matrix using the solution casting method, with akermanite ratios ranging from 0.05% to 2% w/w. To facilitate even distribution of akermanite, 5 wt% triacetin was used as a plasticizer. The resultant PLA/akermanite composite films were evaluated and compared against neat PLA and plasticized PLA films in terms of color, optical, physical, mechanical, thermal and structural properties. Fourier-transform infrared spectroscopy (FT-IR) revealed structural formations attributed to the added plasticizers and akermanite in the PLA matrix. The films containing akermanite showed reduced transparency compared to neat PLA. Differential Scanning Calorimetry (DSC) results indicated an enhancement in crystallinity with the addition of akermanite to the PLA matrix, which suggests improved thermal properties. Mechanical testing showed that the inclusion of triacetin decreased the tensile strength of the PLA films from 31.01 MPa to 29.19 MPa, while the Young's modulus increased from 1.23 GPa to 1.33 GPa. The elongation at break also improved significantly, rising from 5.60% to 8.26%. These changes indicate an overall enhancement in the ductility and stiffness of the films. Additionally, the water solubility and moisture content of the composite films decreased, whereas their water absorption increased compared to neat PLA. These results suggest that the PLA/akermanite composites, with altered physical and mechanical properties, have significant potential for use as biocomposite materials in food packaging applications, offering a sustainable alternative with enhanced performance characteristics. [ABSTRACT FROM AUTHOR]

The mechanical properties of 3D-printed scaffolds for load-bearing implantation are crucial. Although the addition of nanoparticles to polymeric scaffolds can improve their mechanical and biological properties, due to certain limitations in printability, high amounts of reinforcement cannot be used. Therefore, in this study, an attempt was made to use ultrasonic vibration to inhibit nozzle clogging during fused filament fabrication (FFF) of polylactic acid (PLA) scaffolds containing 0, 20, and 40 wt% akermanite (Ak). Nozzle clogging happened during the conventional 3D printing of PLA-40 wt%Ak, while that did not occur during ultrasonic-assisted 3D printing of PLA-40 wt%Ak. Results of X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) indicated that applying ultrasonic vibration had no negative effect on the phases and morphology of the scaffolds. The results obtained by the compression test indicated that applying ultrasonic during 3D printing resulted in almost 27 % increment of elastic modulus and almost 25 % increase of the compressive strength of the scaffolds. As the conclusion, this study highlights the effectiveness of ultrasonic-assisted 3D printing in producing nanocomposite scaffolds with significantly higher nanoparticle loadings, as compared to conventional printing methods. By utilizing ultrasonic vibration during the printing process, the study showcases the possibility of overcoming viscosity limitations and optimizing the mechanical performance of scaffolds for various biomedical applications, including bone tissue engineering.

Porous bioceramic scaffolds were obtained by the 3D printing technique starting from a mixture of hydroxypropyl methyl cellulose and a powder obtained by sol-gel method which contains merwinite, monticellite, pseudowolastonie and periclase.The scaffolds were thermally treated at 1370 °C for 3 h and the main mineralogical compound assessed by XRD was akermanite. The obtained scaffolds have adequate mechanical and biological properties thus a great potential for applications in hard tissue engineering. The positive results obtained for this type of scaffolds are due to the precision of 3D printing technique, i.e. ability to control shape and size of both scaffolds and pores, as well as the high reproducibility. The porous bioactive ceramic scaffolds have adequate compressive strength (up to 3.5 MPa) and exhibit mineralization capacity and potential in stimulating cell adhesion and proliferation as well as bacteriostatic properties. [ABSTRACT FROM AUTHOR]

Although yttria‐stabilized tetragonal zirconia polycrystals (Y‐TZP) ceramics have been widely used as restorative materials due to their high mechanical strength, unique esthetic effect, and good biocompatibility, their general application to implant materials is still limited by their biological inertness and hydrothermal aging phenomenon. Existing studies have attempted to investigate how to enhance the bioactivity or hydrothermal aging resistance of Y‐TZP. Still, more studies need to be done on the modification that combines these two aspects. In this study, Y‐TZP was prepared by 77S bioactive glass (BG) sol and akermanite (AKT) sol infiltration and microwave sintering, which provided Y‐TZP with high bioactivity while maintaining resistance to hydrothermal aging. Results of phase composition evaluation, microstructural characteristics, and mechanical property tests showed that modified Y‐TZP specimens exhibited little or no tetragonal‐to‐monoclinic (t → m) transformation and maintained relatively high mechanical properties after accelerated hydrothermal aging treatment. The in vitro biological behaviors showed that the introduction of 77S BG and AKT significantly promoted cell adhesion, spreading, viability, and proliferation on the surface of modified Y‐TZP ceramics. Therefore, this modification could effectively enhance the bioactivity and hydrothermal aging resistance of Y‐TZP ceramics for its application in dental implant materials. [ABSTRACT FROM AUTHOR]

Psoriasis is a noncontagious, long‐lasting skin infection that affects many people around the world. Numerous therapeutic artificial treatments are available for the treatment of psoriasis, such as photodynamic therapy using broadband ultraviolet (UV) lamps, which have harmful effects on human skin. Similarly, the natural healing systems such as sunlight have a higher risk of sunburn and can cause dangerous forms of skin cancer. Significant light emission of a specific wavelength (in the UV range), and phosphor‐based devices demonstrate the effectiveness of treating psoriasis without damaging the skin. Gd3+‐doped calcium magnesium silicate [Ca2MgSi2O7:Gd3+,(CMS:Gd3+)] phosphor is one of the ideal phosphors that emit specific narrow UV wavelengths for curing psoriasis and is in great demand in the field of dermatology. Photoluminescence analysis at room temperature (~25°C) shows that the synthesized CMS:Gd3+ phosphor emits narrowband UV‐B light with a peak intensity at 314 nm. Comparative studies of the standard action spectrum of psoriasis with the emission spectrum of the CMS:Gd3+ phosphor show that the synthesized phosphor was the most suitable material for treating a variety of diseases, including psoriasis, vitiligo, type‐1 diabetes, dental disease, sleep and mood disorders, and other skin diseases. [ABSTRACT FROM AUTHOR]

Reticulated åkermanite (Ca2MgSi2O7) 3D scaffolds were fabricated by direct ink writing of pastes based on a commercial silicone resin and fillers, such as calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)2) microparticles, followed by heat treatment at 1100 °C in air. To form liquid phase upon firing and thus promote the ionic interdiffusion, borax (Na2B4O7·10H2O) or hydrated sodium phosphate (Na2HPO4·12H2O) were considered as alternative additives. Although leading to scaffolds with different strength-to-density ratio, the two additives did not lead to substantial differences in terms of biological response. All fabricated ceramics exhibited acellular in-vitro bioactivity upon immersion in simulated-body-fluid (SBF) as well as antibacterial activity against S. aureus and E. coli. Direct contact cell viability test, performed with a stromal-cell line from mouse bone marrow (ST-2 cells), indicated no cytotoxicity of both samples determined by the WST-8 assay.

Tissue engineering requires new materials that can be used to replace damaged bone parts. Since hydroxyapatite, currently widely used, has low mechanical resistance, silicate ceramics can represent an alternative. The aim of this study was to obtain porous ceramics based on diopside (CaMgSi2O6) and akermanite (Ca2MgSi2O7) obtained at low sintering temperatures. The powder synthesized by the sol-gel method was pressed in the presence of a porogenic agent represented by commercial sucrose in order to create the desired porosity. The ceramic bodies obtained after sintering thermal treatment at 1050 °C and 1250 °C, respectively, were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) to determine the chemical composition. The open porosity was situated between 32.5 and 34.6%, and the compressive strength had a maximum value of 11.4 MPa for the samples sintered at 1250 °C in the presence of a 20% wt porogenic agent. A cell viability above 70% and the rapid development of an apatitic phase layer make these materials good candidates for use in hard tissue engineering. [ABSTRACT FROM AUTHOR]

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The development of biodegradable Fe-based bone implants has rapidly progressed in recent years. Most of the challenges encountered in developing such implants have been tackled individually or in combination using additive manufacturing technologies. Yet not all the challenges have been overcome. Herein, we present porous FeMn-akermanite composite scaffolds fabricated by extrusion-based 3D printing to address the unmet clinical needs associated with Fe-based biomaterials for bone regeneration, including low biodegradation rate, MRI-incompatibility, mechanical properties, and limited bioactivity. In this research, we developed inks containing Fe, 35 wt% Mn, and 20 or 30 vol% akermanite powder mixtures. 3D printing was optimized together with the debinding and sintering steps to obtain scaffolds with interconnected porosity of 69%. The Fe-matrix in the composites contained the γ-FeMn phase as well as nesosilicate phases. The former made the composites paramagnetic and, thus, MRI-friendly. The in vitro biodegradation rates of the composites with 20 and 30 vol% akermanite were respectively 0.24 and 0.27 mm/y, falling within the ideal range of biodegradation rates for bone substitution. The yield strengths of the porous composites stayed within the range of the values of the trabecular bone, despite in vitro biodegradation for 28 d. All the composite scaffolds favored the adhesion, proliferation, and osteogenic differentiation of preosteoblasts, as revealed by Runx2 assay. Moreover, osteopontin was detected in the extracellular matrix of cells on the scaffolds. Altogether, these results demonstrate the remarkable potential of these composites in fulfilling the requirements of porous biodegradable bone substitutes, motivating future in vivo research. We developed FeMn-akermanite composite scaffolds by taking advantage of the multi-material capacity of extrusion-based 3D printing. Our results demonstrated that the FeMn-akermanite scaffolds showed an exceptional performance in fulfilling all the requirements for bone substitution in vitro, i.e. , a sufficient biodegradation rate, having mechanical properties in the range of trabecular bone even after 4 weeks biodegradation, paramagnetic, cytocompatible and most importantly osteogenic. Our results encourage further research on Fe-based bone implants in in vivo. [Display omitted] [ABSTRACT FROM AUTHOR]

The idea of this work is to reduce the negative effect of ordinary Portland cement (OPC) manufacture on the environment by decreasing clinker production temperature and developing an alternative rankinite binder that hardens in the CO2 atmosphere. The common OPC raw materials, limestone and mica clay, if they contain a higher MgO content, have been found to be unsuitable for the synthesis of CO2-curing low-lime binders. X-ray diffraction analysis (ex-situ and in-situ in the temperature range of 25–1150 °C) showed that akermanite Ca2Mg(Si2O7) begins to form at a temperature of 900 °C. According to Rietveld refinement, the interlayer distances of the resulting curve are more accurately described by the compound, which contains intercalated Fe2+ and Al3+ ions and has the chemical formula Ca2(MgO0.495·FeO0.202·AlO0.303)·(FeO0.248·AlO·Si1.536·O7). Stoichiometric calculations showed that FeO and Al2O3 have replaced about half of the MgO content in the akermanite structure. All this means that only ~4 wt% MgO content in the raw materials determines that ~60 wt% calcium magnesium silicates are formed in the synthesis product. Moreover, it was found that the formed akermanite practically does not react with CO2. Within 24 h of interaction with 99.9 wt% of CO2 gas (15 bar), the intensity of the akermanite peaks does not practically change at 25 °C; no changes are observed at 45 °C, either, which means that the chemical reaction does not take place. As a result, the compressive strength of the samples compressed from the synthesized product and CEN Standard sand EN 196-1 (1:3), and hardened at 15 bar CO2, 45 °C for 24 h, was only 14.45 MPa, while the analogous samples made from OPC clinker obtained from the same raw materials yielded 67.5 MPa. [ABSTRACT FROM AUTHOR]

BACKGROUND: With the continuous development of three-dimensional (3D) printing technology and bone tissue engineering, more and more 3D printed scaffolds have applied in study of bone tissue engineering. The 3D printed scaffold with hollow pipe structure has the advantages of vascular growth and nutrient delivery, which is worthy of further study. OBJECTIVE: To investigate the effect of ionic components released by akermanite on osteogenic differentiation of rat bone marrow mesenchymal stem cells and migration of human umbilical vein endothelial cells and fabricate the 3D-printed akermanite scaffold with hollow-pipe structure with coaxial 3D printing technology. METHODS: The rat bone marrow mesenchymal stem cells and human umbilical vein endothelial cells were cultured with different concentrations of akermanite extracts (1/4, 1/8 and 1/16). The proliferation of rat bone marrow mesenchymal stem cells was detected by CCK-8 assay. Osteogenic differentiation of human umbilical vein endothelial cells was investigated by alkaline phosphatase staining and RT-qPCR. Transwell assay was used to observe the migration of human umbilical vein endothelial cells in response to different concentrations of akermanite extracts. The akermanite scaffold with hollow-pipe structure was prepared using a modified printer nozzle with a core/shell structure with the printing system. The scaffolds were immersed into deionized water and the extracts were collected at set time points. The concentration of ionic products was detected with inductively coupled plasma atomic emission spectrometry. RESULTS AND CONCLUSIOIN: (1) CCK-8 assay indicated that the akermanite extracts had a concentration and time-related effect on promoting the proliferation of bone marrow mesenchymal stem cells. (2) Alkaline phosphatase staining showed that the akermanite extracts had a concentration-related effect on the alkaline phosphatase activity of rat bone marrow mesenchymal stem cells. RT-qPCR indicated that the extracts had a concentration-related effect on the mRNA expression of alkaline phosphatase, collagen-1 and Runx2 of bone marrow mesenchymal stem cells. (3) The akermanite extracts had a concentration-related effect on the migration of human umbilical vein endothelial cells. (4) The scaffolds would continuously release the Ca, Mg and Si ions during immersion into deionized water for 30 days. The akermanite scaffold with hollow pipes was conducive to the release of biologically active ions and had high concentration. (5) The result showed that the akermanite scaffolds with hollow pipes were successfully prepared with the modified 3D printer. The ionic products released by scaffolds had an obvious effect on osteogenesis of rat bone marrow mesenchymal stem cells and promoted migration of human umbilical vein endothelial cells, thereby accelerating vascular regeneration. [ABSTRACT FROM AUTHOR]

[Display omitted] • The optimal temperature for thermochemical reactions of IOTs is 1230–1260 °C. • Diopside and akermanite are the main constituents in the synthesized materials. • Adjusting the constituents of IOTs affects the composition of the synthesized product. • A material rich in diopside or akermanite can be formed by adding SiO 2 /MgO to IOTs. • The synthesized materials exhibit suitability for various potential beneficial applications. Iron ore tailings (IOTs), the residue materials generated during iron ore processing, pose environmental challenges due to their massive volume and potential impact on ecosystems. This study proposes a sustainable approach to manage and utilize this solid waste by converting it into value-added composite materials through high-temperature thermochemical reactions. Experiments are conducted in a tubular reactor at various reaction temperatures and times, and the resulting product samples are comprehensively characterized to elucidate their chemical compositional, physical, microstructural, thermal, and electrical properties. The results reveal that at optimal reaction temperatures (1230–1260 °C) and reaction times (20–120 min), the synthesized product is predominantly composed of diopside (CaMgSi 2 O 6) and akermanite (Ca 2 MgSi 2 O 7). Additionally, we demonstrate that the product can be diopside-rich or akermanite-rich when blending silica and MgO powders into the IOTs to control the starting material composition, opening a promising avenue for large-scale sustainable utilization of industrial solid waste. [ABSTRACT FROM AUTHOR]

The effects of cobalt (Co) substitution on the structural, physico-mechanical properties, as well as the in vitro bioactivity and biodegradability of akermanite (Ca2MgSi2O7) are studied. The XRD patterns showed that the Co substitution did not change the Ca2MgSi2O7 phase. The FESEM micrographs revealed that the partial substitution of Co increased the shrinkage and density of Ca2MgSi2O7 and reduced the grain size. The Co substitution showing the highest mechanical response was 2 mol%. However, the mechanical properties decreased beyond 2 mol% due to the larger grain size. The in vitro degradation test showed that Co substitution altered the degradation profile of Ca2MgSi2O7. However, the degradation rate of Co-substituted Ca2MgSi2O7 was found to be low (1.2%) compared to that of Ca2MgSi2O7 (18%) and led to an alkaline microenvironment. Additionally, an in vitro bioactivity assessment supported the apatite-forming ability of Co-substituted Ca2MgSi2O7 disks after soaking in a SBF solution for 7 and 14 days. Finally, the concentration of Co2+ ions released from the 2 mol% disks was found to be in the non-toxic range. However, a further in vitro and in vivo test needs to be conducted.

The present work reports the synthesis and characterization of polycaprolactone fibers loaded with particulate calcium magnesium silicates, to form composite materials with bioresorbable and bioactive properties. The inorganic powders were achieved through a sol–gel method, starting from the compositions of diopside, akermanite, and merwinite, three mineral phases with suitable features for the field of hard tissue engineering. The fibrous composites were fabricated by electrospinning polymeric solutions with a content of 16% polycaprolactone and 5 or 10% inorganic powder. The physico-chemical evaluation from compositional and morphological points of view was followed by the biological assessment of powder bioactivity and scaffold biocompatibility. SEM investigation highlighted a significant reduction in fiber diameter, from around 3 μm to less than 100 nm after the loading stage, while EDX and FTIR spectra confirmed the existence of embedded mineral entities. The silicate phases were found be highly bioactive after 4 weeks of immersion in SBF, enriching the potential of the polymeric host that provides only biocompatibility and bioresorbability. Moreover, the cellular tests indicated a slight decrease in cell viability over the short-term, a compromise that can be accepted if the overall benefits of such multifunctional composites are considered. [ABSTRACT FROM AUTHOR]

In this work, calcium magnesium silicate ceramics were processed through the sol–gel method in order to study the crystalline and morphological properties of the resulting materials in correlation with the compositional and thermal parameters. Tetraethyl orthosilicate and calcium/magnesium nitrates were employed as sources of cations, in ratios specific to diopside, akermanite and merwinite; they were further subjected to gelation, calcination (600 °C) and thermal treatments at different temperatures (800, 1000 and 1300 °C). The properties of the intermediate and final materials were investigated by thermal analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction and Rietveld refinement. Such ceramics represent suitable candidates for tissue engineering applications that require porosity and bioactivity. [ABSTRACT FROM AUTHOR]

Based on the good osteogenic and angiogenic effects of silicon and magnesium elements, three types of micro-nano magnesium-containing silicates (MS), including akermanite (Ake, Ca 2 MgSi 2 O 7), diopside (Dio, CaMgSi 2 O 6) and forsterite (For, Mg 2 SiO 4), were incorporated into calcium phosphate cement (CPC) to improve its osteogenic and angiogenic performances for clinical application. In this present work, the physicochemical properties, osteogenesis and angiogenesis of MS/CPCs (Ake/CPCs, Dio/CPCs and For/CPCs) were investigated systematically and comparatively. The results showed that all MS/CPCs had good biomineralization and significantly stimulated the osteogenic differentiation of mBMSCs and angiogenic differentiation of HUVECs, respectively. Besides, the stimulating effects were related to not only the category of MS, but also the content of MS. The For/CPCs had a good angiogenic property but their initial setting times were beyond 60 min. The Dio/CPCs showed the lowest biological performance among the three groups of MS/CPCs due to the lower ion release (Si and Mg). The Ake was the ideal modifier that could provide CPC with appropriate physicochemical properties, better osteogenesis and angiogenesis. Simultaneously, a higher addition (10 wt%) of akermanite resulted in the best potential to bone regeneration. Taken together, this research provides an effective approach to improve the overall performance of CPC, and 10Ake/CPC is of great promising prospect in bone repair. [Display omitted] [ABSTRACT FROM AUTHOR]

This report aimed to evaluate the mechanical behavior, bioactivity, and cytotoxicity of novel chitosan/akermanite-TiO 2 (CS/AK/Ti) composite scaffolds fabricated using the 3D-printing method. The morphological and structural properties of these scaffolds were characterized by Fourier transform spectroscopy (FTIR) and scanning electron microscopy (SEM). The mechanical behavior was examined by measuring the compressive strength, while the bioactivity was estimated in the simulated body fluid (SBF), and also the cytotoxicity of the scaffolds was assessed by conducting cell culturing experiments in vitro. It was found that the mechanical properties were considerably affected by the amount of TiO 2. The scaffolds had the possessed bone-like apatite forming ability, which indicated high bioactivity. Furthermore, L929 cells spread well on the surface, proliferated, and had good viability regarding the cell behaviors. The outcomes confirmed that the morphological, biological, and mechanical properties of developed 3D-composite scaffolds nearly mimicked the features of natural bone tissue. In summary, these findings showed that the 3D-printed scaffolds with an interconnected pore structure and improved mechanical properties were a potential candidate for bone tissue applications. [ABSTRACT FROM AUTHOR]

Advanced additive manufacturing techniques have been recently used to tackle the two fundamental challenges of biodegradable Fe-based bone-substituting materials, namely low rate of biodegradation and insufficient bioactivity. While additively manufactured porous iron has been somewhat successful in addressing the first challenge, the limited bioactivity of these biomaterials hinder their progress towards clinical application. Herein, we used extrusion-based 3D printing for additive manufacturing of iron-matrix composites containing silicate-based bioceramic particles (akermanite), thereby addressing both of the abovementioned challenges. We developed inks that carried iron and 5, 10, 15, or 20 vol% of akermanite powder mixtures for the 3D printing process and optimized the debinding and sintering steps to produce geometrically-ordered iron-akermanite composites with an open porosity of 69–71%. The composite scaffolds preserved the designed geometry and the original α-Fe and akermanite phases. The in vitro biodegradation rates of the composites were improved as much as 2.6 times the biodegradation rate of geometrically identical pure iron. The yield strengths and elastic moduli of the scaffolds remained within the range of the mechanical properties of the cancellous bone, even after 28 days of biodegradation. The composite scaffolds (10–20 vol% akermanite) demonstrated improved MC3T3-E1 cell adhesion and higher levels of cell proliferation. The cellular secretion of collagen type-1 and the alkaline phosphatase activity on the composite scaffolds (10–20 vol% akermanite) were, respectively higher than and comparable to Ti6Al4V in osteogenic medium. Taken together, these results clearly show the potential of 3D printed porous iron-akermanite composites for further development as promising bone substitutes. Porous iron matrix composites containing akermanite particles were produced by means of multi-material additive manufacturing to address the two fundamental challenges associated with biodegradable iron-based biomaterials, namely very low rate of biodegradation and insufficient bioactivity. Our porous iron-akermanite composites exhibited enhanced biodegradability and superior bioactivity compared to porous monolithic iron scaffolds. The murine bone cells proliferated on the composite scaffolds, and secreted the collagen type-1 matrix that stimulated bony-like mineralization. The results show the exceptional potential of the developed porous iron-based composite scaffolds for application as bone substitutes. [Display omitted] [ABSTRACT FROM AUTHOR]

Artificial potassium silicate fertilizer (PSF) is a typical slow‐release potassium fertilizer. However, the exact minerals that are released by PSF and the nutrients that are made available to plants remain unclear. This study quantitatively investigated the behaviour of nutrients released from PSF by the batch‐release test and their supply to plants by the plant growth tests, respectively, to determine the quantitative relationship between nutrients released from PSF and taken up by the plant. X‐ray diffraction (XRD) analysis showed that kalsilite, åkermanite, and potassium–magnesium silicate were the most abundant crystalline minerals in PSF. The XRD peaks of åkermanite and potassium–magnesium silicate were absent after citric acid extraction at a liquid/solid ratio of 20 to 100 (CA20 and CA100). Magnesium‐use efficiencies in PSF (11%) and residue treatments after ammonium acetate extraction (AC, 10%) were higher than those in residue treatments after CA20 (1.8%) and CA100 (6.0%). Potassium (%) released by AC in the batch‐release test (4.5%) was compatible with the difference of potassium‐use efficiencies between the treatments of PSF (21%) and the AC‐residue (16%). Likewise, potassium (%) released by CA20 (8.8%) was lower than the difference of potassium‐use efficiencies between the treatments of PSF (21%) and CA20‐residue (7.9%). This study suggests that potassium is rapidly released from potassium–magnesium silicate in PSF and is readily available to plants. [ABSTRACT FROM AUTHOR]

The present paper focuses on the elaboration and characterization of akermanite-rich bioceramics from abundantly available local dolomite and perlite. Different mixtures have been prepared for low-cost ceramic manufacturing by uniaxial pressing method and firing at 1250 °C for 2 h. The obtained results showed that akermanite is the predominant crystalline phase through the addition of natural perlite for a maximum of 30% in weight, accompanied by some small traces of diopside and periclase. The experimental results indicated that the sample M2-B (25 wt% of perlite) is the optimized body from all the tested specimens. The optimized ceramic was subjected to an SBF test to evaluate the bioactivity of the sample, and experimentally the combination between the microstructural and the mineralogical composition of the obtained material after soaking in SBF solution has confirmed the quality of the developed bioceramic by the formation of apatite layer.

Pure nanocrystalline akermanite was successfully synthesized by mechanical activation and heat treatment of talc, calcium carbonate, and silicate. Powders were characterized by thermogravimetric analysis (TGA), x-ray diffractometry (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The formation mechanism was studied in depth. These results showed that akermanite was produced by the formation and consumption of transitionary compounds such as enstatite, wollastonite, larnite, and merwinite. Pure akermanite was synthesized with a crystalline size of 34 nm after ball milling for 20 h and subsequent heat treatment at 900 °C for 1 h.

The treatment of osteochondral defects remains a huge challenge in clinic. The thermotherapy in traditional Chinese medicine is widely used in treating joint disease because the mild heat stimulation can promote the nutrient circulation. Inspired by the function of thermotherapy, we design a new thermotherapy strategy by using black bioceramic scaffolds to build local mild hyperthermal environment for treating osteochondral defects. Herein, black akermanite (B-AKT) bioceramic scaffolds with micro/nano surface structure and excellent photothermal conversion property are successfully fabricated. The temperature of scaffolds can be precisely controlled by near infrared (NIR) irradiation to construct a mild hyperthermal environment (～41°C). The micro/nanostructure on the scaffolds surface well promoted the cell adhesion and nutrition absorption by activating integrins and focal adhesion kinase (FAK). Meanwhile, the mild hyperthermal environment constructed by B-AKT scaffolds can simultaneously induce the chondrogenesis and osteogenesis both in vitro and in vivo by activating the expression of cellular heat shock proteins (HSPs) and corresponding signaling pathways. Furthermore, in rabbit osteochondral defects, mild hyperthermal environment induced by B-AKT scaffolds exhibits stimulatory effects on the integrated regeneration of cartilage and bone. This study proposes a novel therapy strategy of constructing local mild hyperthermal environment by black bioceramic scaffolds to treat osteochondral defects and other joint diseases. [Display omitted] • The black bioceramic scaffolds with surface micro/nano structure and photothermal properties. • The micro/nano surface structure could promote the cells adhesion and nutrition adsorption. • The mild hyperthermal environment was proved to enhance cells differentiation in vitro and repair osteochondral defects in vivo. [ABSTRACT FROM AUTHOR]

The present study illustrates the manufacturing method of hierarchically porous 3D scaffolds based on åkermanite as a promising bioceramic for stereolithography. The macroporosity was designed by implementing 3D models corresponding to different lattice structures (cubic, diamond, Kelvin, and Kagome). To obtain micro-scale porosity, flame synthesized glass microbeads with 10 wt% of silicone resins were utilized to fabricate green scaffolds, later converted into targeted bioceramic phase by firing at 1100 °C in air. No chemical reaction between the glass microspheres, crystallizing into åkermanite, and silica deriving from silicone oxidation was observed upon heat treatment. Silica acted as a binder between the adjacent microspheres, enhancing the creation of microporosity, as documented by XRD, and SEM coupled with EDX analysis. The formation of 'spongy' struts was confirmed by infiltration with Rhodamine B solution. The compressive strength of the sintered porous scaffolds was up to 0.7 MPa with the porosity of 68–84%. [ABSTRACT FROM AUTHOR]

In recent years, amorphous bioglass is used to improve the bioactivity of HA (Ca 10 (PO 4) 6 (OH) 2). Nevertheless, bioglass crystallizes and reacts with the matrix to form a complex phase composition during sintering, resulting in an unclear mechanism for tailoring the properties of HA bioceramics. In this work, TPMS structural HA ceramics fabricated by digital light processing (DLP) were doped by akermanite (Ca 2 MgSi 2 O 7) to better tailor the porosity, bioactivity and mechanical strength. After sintering above 1000 °C, Mg2+ ions from akermanite substitute Ca2+ ions in HA, leading to the decomposition of HA into β-TCP. This process increases the porosity of bioceramics. Additionally, liquid phases sintering caused by akermanite gives rise to the densification and enhancement of grain bonding, thereby reinforcing the mechanical strength of scaffolds. For in vitro bioactivity, as the content of akermanite increases from 0 wt% to 20 wt%, carbonated hydroxyapatite firstly deposits onto the surfaces of scaffolds and then disappears, because excessive Mg2+ prevent the hydroxyapatite crystallization. Finally, bioceramics with 5 wt% and 10 wt% of akermanite and sintering at 1100 °C exhibit a high porosity of over 80% and an appropriate compressive strength of over 2 MPa, while achieving an enhanced in vitro bioactivity and good biocompatibility. After optimization, this kind of porous scaffolds can be well applied to the repair of cancellous bone defect. [ABSTRACT FROM AUTHOR]

In this study, Poly Lactic Acid (PLA) scaffolds containing different amounts of akermanite (Ak) particles were prepared using the fused filament fabrication (FFF) technology. Ak particles were fabricated using sol–gel method. Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) images revealed that the size of the synthesized Ak particles was 100 ± 20 nm. The structure of the 3D printed scaffolds was investigated by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). Distribution of the particles was characterized by Energy Dispersive Spectroscopy (EDS: map), showing the uniform distribution of particles through the PLA matrix. The results of the compression test showed that the strength (plateau stress) of the scaffolds was considerably improved by increasing the Ak particles from 27 ± 2 MPa for the neat polymer scaffold to 45 ± 3 MPa for PLA-30% Ak scaffold, which is near to the values of human cortical bone. The results of the bioactivity test (immersing the scaffolds in the Simulated Body Fluid (SBF) for 7, 14, 21 and 28 days) also indicated the enhanced formation of hydroxyapatite crystals on the scaffold surface upon increasing the immersion time and the Ak particles. While, the increment of Ak particles up to 20 wt.% had no significant effect on printability of scaffolds, and after that, reduced the scaffold printability, so the PLA-Ak 20 wt.% scaffold can be considered as a promising candidate for bone tissue engineering.

Significant interest has been inspired by the exceptional biological performance of akermanite bioceramic in tissue engineering. This exertion investigates effect of fuel on the biomineralisation using three different fuels viz., glycine, L-alanine, and urea. The materials were prepared through sol-gel combustion method by using Glycine, L Alanine and Urea as a fuel and encoded as AK-G, AK-AL, and AK-U. The mechanism associated in the synthesis of these bioceramic was examined by thermal analysis. The pure phase achieved at 900 °C was confirmed by powder XRD, the functional groups were identified by FTIR analysis. When glycine was employed as the fuel, the average crystallite size formed was 32–36 nm; however, for alanine and urea, shows increase in value of 34–40 and 37–43 nm, respectively. Surface morphology and elemental composition were confirmed by SEM/EDX. AFM analysis indicates that Glycine imparts higher surface roughness than other ceramic materials, which promotes nucleation of hydroxyapatite during biomineralization. Among the three samples, AK-Glycine exhibits considerable improvements in bioactivity with a Ca/P ratio of 1.60 which is closer to natural hydroxyapatite (1.67) and makes it an appropriate candidate for bone tissue engineering applications.

Owing to great biocompatibility and high capacity of apatite formation, bioceramics, especially calcium silicate‐based compounds, were extensively employed in orthopedic and dental uses concerning biomedical applications. Lately, akermanite (AK; Ca2MgSi2O7), as a bioceramic containing Ca‐, Mg‐ and Si, has gained an increased level of attention because of its more tunable mechanical characteristics and degradation rate. All studies indicate that this magnesium incorporating Ca‐silicate ceramic has a great capacity to use as a bone graft material to fulfill the necessity of bone reconstruction. Despite the rising interest in using these materials in biomedical fields, there has not yet been an extensive overview of this bioceramic property and its potential benefits. Thus, it has been speculated that this concept and the emergence of akermanite bioactive ceramics might lead to significant upcoming advancements in the field of bone tissue engineering (BTE). Definitely, the approach still requires additional advances to considerably better respond to the vital concerns regarding the clinical application. The review tackles the present research trends on akermanite ceramics for biomedical purposes such as bone scaffold, coating materials, bone cement, and treatment of osteoporotic bone defects, commencing with recent status and shifting to upcoming developments. [ABSTRACT FROM AUTHOR]

Glass microspheres with the exact stoichiometry of åkermanite (Ca2MgSi2O7), one of the most promising modern bioceramics, were produced by the flame synthesis method. The distinctive high cooling rate was found to prevent the crystallization; the size of amorphous microbeads could be correlated with the size of partially crystallized precursor powders, deriving from conventional melt quenching and milling. The glass microspheres were characterized in terms of crystallization and sintering behavior, in the perspective of applications in additive manufacturing of åkermanite‐based scaffolds. The results showed that merwinite (Ca3MgSi2O8) is the primary product of glass devitrification; only in a second stage, merwinite reacts with the residual glass and yields åkermanite. The rapid crystallization, implying limited viscous flow sintering, was tested as an opportunity to create components with complex porosity distribution. [ABSTRACT FROM AUTHOR]

In this work, calcium magnesium silicate ceramics were processed through the sol–gel method in order to study the crystalline and morphological properties of the resulting materials in correlation with the compositional and thermal parameters. Tetraethyl orthosilicate and calcium/magnesium nitrates were employed as sources of cations, in ratios specific to diopside, akermanite and merwinite; they were further subjected to gelation, calcination (600 °C) and thermal treatments at different temperatures (800, 1000 and 1300 °C). The properties of the intermediate and final materials were investigated by thermal analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction and Rietveld refinement. Such ceramics represent suitable candidates for tissue engineering applications that require porosity and bioactivity.

Density functional theory was used to calculate the nonresonance Raman spectra of forsterite (Mg2SiO4) and åkermanite (Ca2MgSi2O7). The Raman tensors are determined from electric polarizibility using finite difference scheme. The Raman reduced spectra (wavenumbers and intensities) are calculated for several typical polarized light scattering geometries for single crystal and polycrystals, demonstrating good agreement with existing published data. In åkermanite, special attention is paid to B2 and E symmetry phonon modes, which exhibit simultaneous infrared and Raman activities, labeled as mixed representations, and are involved in the longitudinal optic (LO)/transverse optic (TO) splitting. Close to zone‐center point, the phonon dispersion curves of mixed modes are analyzed in details, showing for example that mixed modes repulse each other. [ABSTRACT FROM AUTHOR]

In vitro activity is important when considering the choice of a multiphasic bioceramic scaffold as phases can dissolve or transform at different rates. The aim of this study is focused on the synthesis and in vitro analysis of multiphasic ceramics obtained from the melt by directional solidification. Depending on the growth rate of the new composition different bioactive phases coexist in the same sample: akermanite, monticellite, tricalcium phosphate and Nurse's A phase, all of them with potential in the medical area as implant for bone or dental repair. With the knowledge of what and how phases dissolve first, it was possible to design materials to get porous scaffolds or more stable ceramics. [ABSTRACT FROM AUTHOR]

This study reports on microstructural, mechanical, and bioactive properties of the chitosan based composite scaffolds reinforced by akermanite. Firstly, the synthesis of akermanite powders was investigated by three different methods as sol-gel, ball-milling, and spray drying, with additional heat treatments. The morphological and microstructural characterizations revealed that the akermanite powders with the homogeneous and narrow particle size distributions were successfully obtained by spray drying and following heat treatment methods. Secondly, the chitosan/akermanite composite scaffolds were produced by the combination of 3D-bioprinting and lyophilization methods. SEM analyses of produced composite scaffolds indicated the interconnected and open-pore structures. The mechanical test results showed that the increasing akermanite addition enhanced the strength of composite scaffolds significantly. The bioactivity test results presented that the composite scaffolds had good in vitro bioactivity based on their good apatite-formation abilities on their surfaces and in simulated body fluid. According to the results, the bioactive 3D-printed scaffold with improved mechanical properties promises the good potential for bone tissue engineering applications. [ABSTRACT FROM AUTHOR]

Osteochondral regeneration is a major challenge due to the different composition of cartilage and subchondral bone and different biochemical, biomechanical and biological properties. For this reason, a biomimetic scaffold is necessary to provide different biological signals needed to allow for osteochondral regeneration [1]. This study aims to design novel biodegradable cross-linked composite hydrogels based on gelatin and polysaccharidic components (chondroitin-4-sulphate and hyaluronic acid), mixed with akermanite and enriched with small bioactive molecule (icariin). Akermanite was used as a better alternative to conventional ceramics due to its bone-like apatite formation ability and good bioactivity [2]. Icariin (Ica) flavonoid (from traditional Chinese medicine Epimedium herb) was used as substitute for growth factors to enhance cell proliferation and chondrogenic and osteogenic differentiation [3]. Variants of biodegradable cross-linked composite hydrogel based on gelatin, polysaccharidic components (chondroitin-4-sulphate and hyaluronic acid), in two ratios of 2:0.8:0.2 and 2:0.08:0.02 (w/w/w), were developed and mixed with akermanite, at a ratio of 2:1 (w/w). Subsequently, both composite hydrogel variants were cross-linked with (N,N-(3-dimethylaminopropyl)-N-ethyl carbodiimide (EDC) and enriched with small bioactive molecule (icariin). The obtained cross-linked composite hydrogel variants enriched with Ica were characterized related to enzymatic biodegradation (type I collagenase), swelling capacity, degree of cross-linking (TNBS assay), and morphology (SEM). Their cytocompatibility was evaluated by analyses of cell viability and cellular cycle (flow cytometry), cell proliferation (Neutral Red assay), and cell adhesion to composite hydrogels (SEM) using NCTC clone L929 cell line. The final results show that both cross-linked composite hydrogel variants enriched with Ica presented optimal physicochemical and structural properties to be used as a scaffold for osteochondral healing. Our data did not reveal any toxicity of composite hydrogels in the NCTC cell line within the tested range of concentrations (10–50 mg/mL). Additionally, cells were capable of spreading and proliferating on the surface of composite hydrogels. The designed biodegradable cross-linked composites enriched with Ica are recommended for further studies as natural temporary scaffolds, which can allow both cartilage and subchondral regeneration with implications for the management of osteochondral healing.

The present study illustrates the manufacturing method of hierarchically porous 3D scaffolds based on åkermanite as a promising bioceramic for stereolithography. The macroporosity was designed by implementing 3D models corresponding to different lattice structures (cubic, diamond, Kelvin, and Kagome). To obtain micro-scale porosity, flame synthesized glass microbeads with 10 wt% of silicone resins were utilized to fabricate green scaffolds, later converted into targeted bioceramic phase by firing at 1100 °C in air. No chemical reaction between the glass microspheres, crystallizing into åkermanite, and silica deriving from silicone oxidation was observed upon heat treatment. Silica acted as a binder between the adjacent microspheres, enhancing the creation of microporosity, as documented by XRD, and SEM coupled with EDX analysis. The formation of ‘spongy’ struts was confirmed by infiltration with Rhodamine B solution. The compressive strength of the sintered porous scaffolds was up to 0.7 MPa with the porosity of 68–84%.

This paper reports on the influence of substituting barium (Ba2+) ions on the structural, mechanical and in vitro biological properties of akermanite prepared via high-energy wet planetary ball milling and sintering. The results obtained showed that the properties of the prepared bioceramics are highly dependent on Ba2+ content. It was found that Ba2+ resulted in improved densification (≥90%), and better apatite-forming ability of akermanite ceramic, without altering phase composition. Herein, the enhancement in diametral tensile strength (DTS), Vickers microhardness (H V) and fracture toughness (K IC) for Ba2+-doped akermanite bioceramics are reported for the first time. It was also found that after 21 days of immersion in simulated body fluid (SBF) solution, the doped ceramic surface was completely covered with apatite crystals, indicating Ba2+ encouraged apatite crystals deposition. Therefore, Ba2+-doped akermanite bioceramic could be an attractive alternative bioresorbable material for bone tissue engineering applications. [ABSTRACT FROM AUTHOR]

Silicones mixed with oxide fillers are interesting precursors for several bioactive glass-ceramics. A key point is represented by the coupling of synthesis and shaping, since highly porous bodies, in form of foams or scaffolds, are first manufactured with silicones in the polymeric state, at low temperature, and later subjected to ceramic transformation. After successful application of direct ink writing, the present study illustrates the tuning of silicone-based mixtures in order to form åkermanite (Ca 2 MgSi 2 O 7) reticulated scaffolds by digital light processing. This implied the selection of commercial silicones, producing stable and homogeneous blends with a photocurable resin and enabling the manufacturing of defect-free printed scaffolds, before and after firing, without fillers. The blends were further refined with the introduction of fillers, followed by firing at 1100 °C, in air. Optimized samples (from H44 resin) and reactive fillers (including up to 4.5 wt.% borax additive), led to crack-free and phase-pure scaffolds with microporous struts. [ABSTRACT FROM AUTHOR]

In this study, a series of Er3+/Yb3+ co-doped Ca–Mg–Si glasses were prepared via the containerless processing. Phase composition and luminescent properties of the prepared materials were investigated through XRD and spectrometry, and bioactivity, biocompatibility and cytotoxicity were evaluated. The XRD patterns indicated that akermanite (AKT) ceramic powders were completely transformed into the glassy phase (AKT-G, EYA) through the containerless processing, which exhibit upconversion luminescence, and the luminescence intensity increased with the increase of the doping amount of Er3+ and Yb3+. High amount of Yb3+ doping and existence of Ca2+ in glasses resulted in more intensive red-light emission. The SEM observation, combined with EDS analysis, and cell culture experiments showed that the as-prepared glasses were nontoxic, biocompatible and bioactive. All these results demonstrated that the containerless processing is a facile method for preparing homogeneous luminescent bioactive glasses. Furthermore, this luminescent Ca–Mg–Si glasses may be used as bone implant materials to study the in vivo distribution of degradation products of bone implants, which may be of great significance for the development and clinical application of new bone grafting materials. [ABSTRACT FROM AUTHOR]

In osteoporosis scenario, tissue response to implants is greatly impaired by the deteriorated bone regeneration microenvironment. In the present study, a Mg-containing akermanite (Ak) ceramic was employed for the treatment of osteoporotic bone defect, based on the hypothesis that both beneficial ions (e.g. Mg2+ ect.) released by the implants and the weak alkaline microenvironment pH (μe-pH) it created may play distinct roles in recovering the abnormal bone regeneration by stimulating osteoblastic anabolic effects. The performance of Ak, β-tricalcium phosphate (β-TCP) and Hardystone (Har) in healing a 3 mm bone defect on the ovariectomized (OVX) osteoporotic rat model was evaluated. Our results indicated that, there's more new bone formed in Ak group than in β-TCP or Har group at week 9. The initial μe-pHs of Ak were significantly higher than that of the β-TCP and Blank group, and this weak alkaline condition was maintained till at least 9 weeks post-surgery. Increased osteoblastic activity which was indicated by higher osteoid secretion was observed in Ak group at week 4 to week 9. An intermediate layer which was rich in phosphorus minerals and bound directly to the new forming bone was developed on the surface of Ak. In a summary, our study demonstrates that Ak exhibits a superior bone regenerative performance under osteoporosis condition, and might be a promising candidate for the treatment of osteoporotic bone defect and fracture.

The present investigation is dedicated to the manufacturing of reticulated three-dimensional akermanite scaffolds, developed by direct reaction between silica, from the oxidation of a commercial silicone resin and oxide fillers, forming pastes for direct ink writing. Crack-free scaffolds, with dense and regular struts, were due to the use of CaCO 3 (micro) and MgO nano-particles as reactive fillers. An excellent phase purity was obtained, with the help of the liquid phase provided by anhydrous sodium borate (Na 2 B 4 O 7), upon firing. The structure of the scaffolds, finally, was successfully modified by using Mg(OH) 2 and hydrated sodium borate: besides macro-porosity from direct ink writing, the new scaffolds exhibited homogenous 'spongy' struts (owing to water vapor release in the heating step), with no crack. Both types of scaffolds (with dense or porous struts) exhibited remarkable strength-to-density ratios. [ABSTRACT FROM AUTHOR]

Scaffold assisted tissue engineering presents a promising approach to repair diseased and fractured bone. For successful bone repair, scaffolds need to be made of biomaterials that degrade with time and promote osteogenesis. Compared to the commonly used ß‐tricalcium phosphate scaffolds, Akermanite (AKM) scaffolds were found to degrade faster and promote more osteogenesis. The objective of this study is to synthesize AKM micro and nanoparticle reinforced poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate; PHBV) composite scaffolds using selective laser sintering (SLS). The synthesized composite scaffolds had an interconnected porous microstructure (61–64% relative porosity), large specific surface areas (31.1–64.2 mm−1) and pore sizes ranging from 303 to 366 and 279 to 357 μm in the normal and lateral direction, respectively, which are suitable for bone tissue repair. The observed hydrophilic nature of the scaffolds and the swift water uptake was due to the introduction of numerous carboxylic acid groups on the scaffold surface after SLS, circumventing the need for postprocessing. For the composite scaffolds, large amounts of AKM particles were exposed on the skeleton surface, which is a requirement for cell attachment. In addition, the particles embedded inside the skeleton helped to significantly reinforce the scaffold structure. The compressive strength and modulus of the composite scaffolds were up to 7.4 and 103 MPa, respectively, which are 149 and 197% of that of the pure PHBV scaffolds. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2596–2610, 2019. [ABSTRACT FROM AUTHOR]

Electrospinning, as an effective method for preparation of scaffolds for cell growth templates, has attracted great attention. In this study electrospinning was used to prepare poly (vinyl alcohol) (PVA)/chitosan scaffolds for bone tissue engineering. In order to improve the bioactivity and mechanical properties of the fibrous scaffolds, 0.5, 1 and 2 wt% akermanite, a calcium silicate based bioceramic, was added to the electrospinning solution. The morphology of the electrospun scaffolds was observed by using field emission-scanning electron microscopy and their mechanical strengths were analyzed by tension tests. The results showed that the formed scaffolds consisted of fibers with less than 100 nm diameter. In the case of the composite containing 1 wt% akermanite, the fibers were more homogeneous and no beads were formed during electrospinning, while in the composite containing 2 wt% akermanite a considerable number of beads were formed which we attribute to an improper viscosity of the electrospinning solution. Among the different compositions, the composite containing 1 wt% akermanite showed higher ultimate tensile strength (10.6 MPa) and fracture strain (9%). These values were increased by crosslinking the scaffold by reaction with glutaraldehyde, up to 13 MPa and 9.4%, respectively. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of Sr substitution on the structure, mechanical properties, bioactivity, and biodegradation of akermanite (Ca 2 MgSi 2 O 7). Samples were synthesized through solid-state synthesis followed by heat treatment at 1200 °C and 1250 °C. X-ray diffraction patterns showed that Sr substitution did not change the Ca 2 MgSi 2 O 7 phase. Fourier transform infrared spectra demonstrated that the silicate structure of Ca 2 MgSi 2 O 7 also remained unchanged. The field emission scanning electron microscopy revealed that partial Sr substitution enhanced the density of Ca 2 MgSi 2 O 7 and reduced the grain size. The optimum dopant with the highest mechanical properties was 0.05Sr. However, the mechanical properties decreased beyond 0.05Sr because of the large grain size. The mechanical properties of Sr-substituted samples sintered at 1250 °C were lower due to high liquid phase formation. Sr substitution supported apatite formation and controlled Ca 2 MgSi 2 O 7 degradation after the samples were soaked in simulated body fluid solution (SBF). [ABSTRACT FROM AUTHOR]