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1.
Polyvinylalcohol/chitosan (PVA/CS) is an excellent dual-network hydrogel material, but some significant challenges remain in fabricating composites with specific structures. In this study, 3D gel printing (3DGP) combined with a water-level controlled crosslinker bath was proposed for the rapid in-situ prototyping of PVA/CS/Fe 3O 4 magnetic hydrogel scaffolds. Specifically, the PVA/CS/Fe 3O 4 hydrogels were extruded into the crosslinker water to achieve rapid in-situ gelation, improving the printability of hydrogel scaffolds. The effect of the PVA/CS ratio on the rheological and mechanical properties of dual-network magnetic hydrogels was evaluated. The printing parameters were systematically optimized to facilitate the coordination between the crosslinking water bath and printer. The different crosslinking water baths were investigated to improve the printability of PVA/CS/Fe 3O 4 hydrogels. The results showed that the printability of the sodium hydroxide (NaOH) crosslinker was significantly better than that of sodium tripolyphosphate (TPP). The magnetic hydrogels (PVA: CS= 1: 1) crosslinked by NaOH had better compressive strength, swelling rate, and saturation magnetization of 1.17 MPa, 92.43%, and 22.19 emu/g, respectively. The MC3T3-E1 cell culture results showed that the PVA/CS/Fe 3O 4 scaffolds promoted cell adhesion and proliferation, and the scaffolds crosslinked by NaOH had superior cytocompatibility. 3DGP combined with a water-level controlled crosslinker bath offers a promising approach to preparing magnetic hydrogel materials. 相似文献
2.
The biodegradable ceramic scaffolds with desirable pore size, porosity and mechanical properties play a crucial role in bone tissue engineering and bone transplantation. A novel porous β-dicalcium silicate (β-Ca 2SiO 4) ceramic scaffold was prepared by sintering the green body consisting of CaCO 3 and SiO 2 at 1300 °C, which generated interconnected pore network with proper pore size of about 300 μm and high compressive strength (28.13±5.37–10.36±0.83 MPa) following the porosity from 53.54±5.37% to 71.44±0.83%. Porous β-Ca 2SiO 4 ceramic scaffolds displayed a good biocompatibility, since human osteoblast-like MG-63 cells and goat bone mesenchymal stem cells (BMSCs) proliferated continuously on the scaffolds after 7 d culture. The porous β-Ca 2SiO 4 ceramic scaffolds revealed well apatite-forming ability when incubated in the simulated body fluid (SBF). According to the histological test, the degradation of porous β-Ca 2SiO 4 ceramic scaffolds and the new bone tissue generation in vivo were observed following 9 weeks implantation in nude mice. These results suggested that the porous β-Ca 2SiO 4 ceramic scaffolds could be potentially applied in bone tissue engineering. 相似文献
3.
Nano SiO 2 and MgO particles were incorporated into β-tricalcium phosphate (β-TCP) scaffolds to improve the mechanical and biological properties. The porous cylindrical β-TCP scaffolds doped with 0.5 wt % SiO 2, 1.0 wt % MgO, 0.5 wt % SiO 2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped β-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the phase transformation from β-TCP to α-TCP was inhibited after the addition of MgO. The compressive strength of scaffold was improved from 3.12 ± 0.36 MPa (β-TCP) to 5.74 ± 0.62 MPa (β-TCP/SiO 2), 9.02 ± 0.55 MPa (β-TCP/MgO) and 10.43 ± 0.28 MPa (β-TCP/SiO 2/MgO), respectively. The weight loss and apatite-forming ability of the scaffolds were evaluated by soaking them in simulated body fluid. The results demonstrated that both SiO 2 and MgO dopings slowed down the degradation rate and improved the bioactivity of β-TCP scaffolds. In vitro cell culture studies indicated that SiO 2 and MgO dopings facilitated cell attachment and proliferation. Combined addition of SiO 2 and MgO were found optimal in enhancing both the mechanical and biological properties of β-TCP scaffold. 相似文献
4.
The present work focused on the preparation of CEL2 bioactive glass (SiO 2–P 2O 5–CaO–MgO–K 2O–Na 2O) scaffolds loaded with chitosan microspheres. Chitosan microspheres, with a mean particle size of 0.55 μm ± 0.25 μm and loaded with acetaminophen, were obtained through the water-in-oil single emulsion solvent evaporation method and were adhered to the surface of the scaffolds by a simple dip-coating technique. The characterization of the microsphere-loaded scaffolds, before and after immersion in simulated body fluid (SBF), was performed by scanning electron microscopy, X-ray diffraction, and infrared spectroscopy. In vitro bioactivity was performed for 21 days. The glass-ceramic microsphere-loaded scaffolds showed more than 70% interconnected porosity and an average compressive strength of 1.2 ± 0.43 MPa after immersion in SBF. They also showed the formation of a hydroxyapatite layer from the first day of immersion in SBF, demonstrating their high bioactivity. The microspheres were shown to be homogeneously dispersed on the scaffold surfaces. After 120 hours, the biologic tests showed good fibroblast cell proliferation onto the scaffolds. The encapsulated drug in the microspheres was released by diffusion in a sustained manner (90% and 99% in 200 hours). The results suggest that scaffolds have a promising role in applications of bone tissue engineering. 相似文献
5.
Chopped quartz fiber-reinforced fused silica (SiO 2f/SiO 2) composites were fabricated by stereolithography. The fiber orientation characteristics and crack distributions after the debinding process of the green bodies were investigated. The results showed that the distribution of fibers presented orientation characteristics; additionally, the number of cracks after debinding decreased as the fiber content increased and the cracks oriented along the fiber orientation. The mechanical properties of SiO 2f/SiO 2 ceramics with different fiber contents were also considered. As a result, a compressive strength of 51.2 MPa and flexural strength of 24.3 MPa were achieved for the SiO 2f/SiO 2 ceramic with 4 wt% fiber, and a sintered cambered structure with a size over 150 mm × 150 mm × 3 mm was fabricated successfully without cracking and deformation for the SiO 2f/SiO 2 composites with a fiber content of 4 wt% and 6 wt%. 相似文献
6.
The incorporation of a bioactive inorganic phase in polymeric scaffolds is a good strategy for the improvement of the bioactivity and the mechanical properties, which represent crucial features in the field of bone tissue engineering. In this study, spray-dried mesoporous bioactive glass particles (SD-MBG), belonging to the binary system of SiO 2-CaO (80:20 mol%), were used to prepare composite scaffolds by freeze-drying technique, using a silk fibroin matrix. The physico-chemical and biological properties of the scaffolds were extensively studied. The scaffolds showed a highly interconnected porosity with a mean pore size in the range of 150 µm for both pure silk and silk/SD-MBG scaffolds. The elastic moduli of the silk and silk/SD-MBG scaffolds were 1.1±0.2 MPa and 6.9±1.0 MPa and compressive strength were 0.5±0.05 MPa and 0.9±0.2 MPa, respectively, showing a noticeable increase of the mechanical properties of the composite scaffolds compared to the silk ones. The contact angle value decreased from 105.3° to 71.2° with the incorporation of SD-MBG particles. Moreover, the SD-MBG incorporation countered the lack of bioactivity of the silk scaffolds inducing the precipitation of hydroxyapatite layer on their surface already after 1 day of incubation in simulated body fluid. The composite scaffolds showed good biocompatibility and a good alkaline phosphatase activity toward human mesenchymal stromal cells, showing the ability for their use as three-dimensional constructs for bone tissue engineering. 相似文献
7.
The beta- and gamma-dicalcium silicate (β- and γ-Ca 2SiO 4) ceramics were prepared by sintering β-Ca 2SiO 4 greens at 1100, 1300, and 1450 °C, respectively, after compacting with cold isostatic pressure. The phase transition from β- to γ-phase of polymorphic ceramics occurred at 1100–1300 °C. Bending strength and Vickers hardness of β-Ca 2SiO 4 ceramic sintered at 1100 °C were only 25.6 ± 3.8 MPa and 0.41 ± 0.05 GPa. In contrast, the mechanical properties of the γ-Ca 2SiO 4 were improved remarkably when the ceramics were sintered at 1450 °C, corresponding to bending strength, 97.1 ± 6.7 MPa; Vickers hardness, 4.34 ± 0.35 GPa, respectively. The ceramics were soaked in the simulated body fluid (SBF) for various periods were characterized by SEM, XRD, FTIR, and EDS analysis, and the results indicated that the carbonated hydroxyapatite (CHA) was formed on the surface of the ceramics within 3 days. In addition, cell attachment assay showed that the ceramics supported the mesenchymal stem cells adhesion and spreading, and the cells established close contacts with the ceramics after 1 day of culture. These findings indicate that the γ-Ca 2SiO 4 ceramic possesses good bioactivity, biocompatibility and mechanical properties, and might be a promising bone implant material. 相似文献
8.
Nanofibrous biocomposite scaffolds of chitosan (CS), PVA, and hydroxyapatite (HA) were prepared by electrospinning. The scaffolds were characterized by FTIR, SEM, TEM, and XRD techniques. Tensile testing was used for the characterization of mechanical properties. Mouse fibroblasts (L929) attachment and proliferation on the nanofibrous scaffold were investigated by MTT assay and SEM observation. FTIR, TEM, and XRD results showed the presence of nanoHA in the scaffolds. The scaffolds have porous nanofibrous morphology with random fibers in the range of 100–700 nm diameters. The CS/PVA (90/10) fibrous matrix (without HA) showed a tensile strength of 3.1 ± 0.2 MPa and a tensile modulus 10 ± 1 MPa with a strain at failure of 21.1 ± 0.6%. Increase the content of HA up to 2% increased the ultimate tensile strength and tensile modulus, but further increase HA up to 5–10% caused the decrease of tensile strength and tensile modulus. The attachment and growth of mouse fibroblast was on the surface of nanofibrous structure, and cells' morphology characteristics and viability were unaffected. A combination of nanofibrous CS/PVA and HA that mimics the nanoscale features of the extra cellular matrix could be promising for application as scaffolds for tissue regeneration, especially in low or nonload bearing areas. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
9.
Monodisperse SrFe 12O 19 (SrM) nanoflakes were successfully fabricated via a modified hydrothermal method. The effects of Fe 3+/Sr 2+ ( RF/S) and OH −/NO 3− ( RO/N) molar ratio on phase, structure and morphology of the products were investigated by XRD, FT-IR, FESEM, and TEM. Meanwhile, the magnetic properties of the product were investigated via vibrating sample magnetisem (VSM). Results demonstrated that when the RF/S=5 and RO/N=2, the single phase SrFe 12O 19 particles were obtained. The as-obtained SrFe 12O 19 particles had monodisperse nanoflake structure and nano-micro scale in vertical and horizontal direction of SrM ferrite particle. The magnetic property results showed that such structure SrM ferrite particle had prospective saturation magnetization and coercivity, the largest values of Ms and Hc were 62.96 emu/g and 94.83 kA/m, respectively, which make it have a potential application as magnetic recording media and magneto-optical devices material. 相似文献
10.
In order to improve the bonding property of joint between SiC modified carbon/carbon (C/C) composites and Li 2O–Al 2O 3–SiO 2 (LAS) glass ceramics, SiC nanowires were attempted as the reinforcement materials in the interface region of SiC transition layer and Li 2O–MgO–Al 2O 3–SiO 2 (LMAS) gradient joining interlayer. The C/C–LAS joint with SiC nanowire-reinforced interface layer was prepared by a three-step technique of pack cementation, in situ reaction and hot-pressing. The microstructure and thermal shock resistance of the as-prepared joints were examined. The average shear strength of the joined samples with SiC nanowires increased from 24.9 MPa to 31.6 MPa after 40 thermal cycles between 1000 °C and room temperature, while that of the joined samples without SiC nanowires dropped from 21.4 MPa to 8.3 MPa. The increase of thermal shock resistance of the C/C–LAS joints was mainly attributed to the toughening mechanism of SiC nanowires by pullout, bridging and crack deflection. 相似文献
11.
The study on the magnetocrystalline anisotropy (MA) of La–Co co-substituted strontium hexaferrite (La–Co SrM) shows a joint effect of Fe 2+ and Co 2+ ions in the enhancement of MA. Since the role of Fe 2+ single ion has been studied with La-substituted strontium ferrite, in this work, Co-substituted strontium hexaferrite SrFe 12-xCo xO 19 (Co-SrM) single crystals were successfully grown for 0 ≤ x ≤ 0.31 by the Na 2CO 3 flux method to elucidate the anisotropy of Co 2+ single ions. Co-substitution in this preparation condition has a limit solubility of 0.31 and enhances uniaxial magnetic anisotropy field HA by 19% for 0.03 = x ≤ 0.11, with a mere loss of 7% of saturation magnetization MS at 5 K. The enhanced HA of Co-SrM is reported for the first time, even higher than that of La–Co SrM, which is suitable to be used as permanent magnets in this concentration range. But with the further substitution of Co, the planar anisotropy of x = 0.31 was observed at 5 K. The potential nonlinear magnetic structure of Co-SrM remains to be discovered for magnetoelectric effects. This work is also of great significance as a complement to the magnetocrystalline anisotropy study of La–Co SrM. 相似文献
12.
Thiol-functionalized mesoporous poly (vinyl alcohol)/SiO 2 composite nanofiber membranes and pure PVA nanofiber membranes were synthesized by electrospinning. The results of Fourier transform infrared (FTIR) indicated that the PVA/SiO 2 composite nanofibers were functionalized by mercapto groups via the hydrolysis polycondensation. The surface areas of the PVA/SiO 2 composite nanofiber membranes were >290 m 2/g. The surface areas, pore diameters and pore volumes of PVA/SiO 2 composite nanofibers decreased as the PVA content increased. The adsorption capacities of the thiol-functionalized mesoporous PVA/SiO 2 composite nanofiber membranes were greater than the pure PVA nanofiber membranes. The largest adsorption capacity was 489.12 mg/g at 303 K. The mesoporous PVA/SiO 2 composite nanofiber membranes exhibited higher Cu 2+ ion adsorption capacity than other reported nanofiber membranes. Furthermore, the adsorption capacity of the PVA/SiO 2 composite nanofiber membranes was maintained through six recycling processes. Consequently, these membranes can be promising materials for removing, and recovering, heavy metal ions in water. 相似文献
13.
In this work, h-BN based composites containing amorphous silica and ytterbium silicate glass phases were successfully fabricated by in situ hot pressing process. The powder mixtures of h-BN, Yb 2O 3, SiO 2 and sintering additive (Al 2O 3) were hot pressed at 1880?°C for 1?h under 30?MPa in Ar atmosphere. In the composites, β-Yb 2Si 2O 7 phase produced from the reaction between Yb 2O 3 and SiO 2 disappears completely and transforms to Yb-Si-Al-O glass when the amount of Al 2O 3 is ≥1.5?wt.%. The Vickers hardness, flexural strength, and compressive strength reached the maximum values of 2.38?±?0.08?GPa, 337?±?22?MPa and 950?±?34?MPa, respectively, as 1.5?wt.% Al 2O 3 was added. The strengthening effects were attributed to the fine spherical microstructure of Yb-Si-Al-O glass particles, strong [AlO 4] coordination state, and residual compressive stress in glass phases. 相似文献
14.
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–Fe 3O 4 are considered in this study. These materials with two various space-agents such as sodium chloride (NaCl) and sodium bicarbonate (NaHCO 3) 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. 相似文献
15.
Poly(vinyl alcohol)/nano‐silica (PVA/nano‐SiO 2) films were prepared through extrusion blowing with the addition of water and glycerin as plasticizer. The characteristic properties of PVA/nano‐SiO 2 films were investigated by differential scanning calorimetry, dynamic mechanical analysis, Haake torque rheometry, and atomic force microscopy (AFM). The results showed that the mechanical properties of PVA/nano‐SiO 2 were improved dramatically. The tensile strength of the nanofilms increased from 62 MPa to 104 MPa with loading 0.3 wt % nano‐SiO 2 and the tear strength was improved from 222 KN/m to 580 KN/m. The crystallinity of the films loaded with 0.4 wt. % nano‐SiO 2 decreased from 32.2% to 21.0% and the AFM images indicated that the amorphous region of nanofilms increased with increasing nano‐SiO 2 content. The storage modulus and loss modulus increased to two and nearly three times with 0.3 wt % nano‐SiO 2 loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
16.
In this study, the carbon nanotubes (CNTs) are successively coated via sol-gel method with SiO 2 (SiO 2@CNTs), followed by grafting with 3-merraptnpropyltrimethnxysilane and oxidation with hydrogen peroxide to yield dual-modified CNTs (SSiO 2@CNTs). The SSiO 2@CNTs material is applied to prepared chitosan (CS) based composite proton exchange membranes by the incorporation of various content of SSiO 2@CNTs, the structure and properties of as-prepared composite membranes are fully investigated. Compared to pristine CS membrane, the SSiO 2@CNTs-filled composite membranes show improved thermal stability, mechanical stability, and methanol resistance, owing to the effective interface interaction and good compatibility between SSiO 2@CNTs and CS matrix. Additionally, the doping of SSiO 2@CNTs also generates a positive effect on the electrochemistry performance, due to the construction of abundant transport channel and providing more proton sources or proton sites. Particularly, the CS/SSiO 2@CNTs-7 membrane exhibits tensile strength of about 40.1 MPa and proton conductivity of 35.8 mS cm −1 at 80 °C, which is almost 1.6 and 2.0 times higher than pure CS membrane, and lower methanol permeability of 0.9 × 10 −6 cm 2 s −1. The direct methanol fuel cell performance (DMFC) of CS/SSiO 2@CNTs-7 membrane is also improved with open circuit voltage of 0.67 V and maximum power density of 60.7 mW cm −2 at 70 °C. 相似文献
17.
Biodegradable films are used in a variety of applications, including packaging. However, their use is limited due to their high moisture and water sensitivity. In this work, cassava starch (CS) was blended with poly(vinyl alcohol) (PVA). Silica particles (SiO2) were incorporated to increase the hydrophobicity of the blend by intermolecular interaction through hydrogen bonding between the three components. Instead of a plasticizer or crosslinker, a small amount of triethylamine was added to eliminate residual acetate groups in PVA. The miscibility of CS and PVA phases was confirmed by smooth fracture surfaces and a single glass transition temperature. When SiO2 content was below 5% (wt), the particles were well dispersed in a continuous phase of polymer matrix. At this loading of SiO2, the increase in tensile strength was as high as 170% and in elongation-at-break, 250%. All loadings of SiO2 increased thermal stability of the blend films because silanol groups on the surface of SiO2 particles formed effective interfacial interactions with hydroxyl groups of the polymers. These interactions also prevented the ingress of water molecules, significantly increasing the hydrophobicity of the films. The water contact angle increased as high as 113° and moisture absorbency and water solubility were low. These highly hydrophobic, photodegradable, biodegradable CS/PVA/SiO2 films show great potential as a low-cost, eco-friendly material. 相似文献
18.
Si 3N 4 based composites were successfully sintered by spark plasma sintering using low cost BaCO 3, SiO 2 and Al 2O 3 as additives. Powder mixtures were sintered at 1600–1800 °C for 5 and 10 min. Displacement-temperature-time (DTT) diagrams were used to evaluate the sintering behavior. Shrinkage curve revealed that densification was performed between 1100 and 1700 °C. The specimen sintered at 1700 °C showed the maximum relative density (99.8±0.1%), flexural strength (352±16 MPa), Vickers harness (11±0.1 GPa) and toughness (5.6±0.05 MPa m 1/2). 相似文献
19.
Silicate-bonded porous SiC scaffolds with lamellar structures were prepared by freeze casting and liquid-phase sintering. It was found that the viscosity and solidification velocity of SiC water-based slurries with 30 vol% solid loading decreased with increasing Al 2O 3–MgO (AM) addition. As the AM content increased from 10 to 30 wt%, the lamellae of the sintered scaffolds became denser and the porosity decreased from 69±0.5% to 62±0.5%, while the compressive strength improved from 25±2 to 51±2 MPa. The dynamics of pressureless infiltration for an Al–12 Si–10 Mg alloy on the SiC porous scaffold was measured and the composites with lamellar-interpenetrated structures were successfully produced. Both the compressive strength and the elastic modulus of the composites increased with increasing AM content. The maximum strength reached 952±24 MPa and the highest elastic modulus about 156 GPa, respectively, in a longitudinal direction, increasing about 32% and 11% as compared with those of the composites without AM. 相似文献
20.
The high performance Si 3N 4 ceramic was prepared firstly for TiO 2, Y 2O 3 and MgO as pressureless sintering additives. Si 3N 4 ceramic with relative density of 99.6% and flexural strength of 785 ± 23.3 MPa could be obtained with 3 mol% TiO 2 and sintered at 1800 °C for 2 h. After annealing at 1700 °C, the facture toughness of sample of 1 mol% TiO 2 increased from 8.31 ± 0.28 MPa m 1/2 to 9.84 ± 0.16 MPa m 1/2. The flexural strength of sample of 2 mol% TiO 2 increased from 707 ± 26 MPa to 981 ± 16 MPa, thermal conductivity increased from 57.8 W/(m·K) to 68.49 W/(m·K). The XRD results showed that the ratio of I101/ I210 and grain height reached to 1.84 and 5 μm of the sample of 3 mol% TiO 2, respectively. The present investigation revealed that the three-dimensional array of highly oriented crystalline Si 3N 4 micro rods could be prepared which array on the homogeneous substrates by using TiO 2 as agent. This phenomenon may propose a method that the mechanical properties the Si 3N 4 ceramics added TiO 2 can be improved significantly after annealing process. 相似文献
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