Journal of Advanced Materials in Engineering (Esteghlal)

The positive effect of Si and Zn ions on bone formation and metabolism has already been confirmed. The aim of this study was preparation and characterization of Willemite (Zn2SiO4) for the repair of bone defects. Willemite was prepared through solid state reaction. Phase analysis and chemical compositions were investigated. The zeta potential of the nanoparticles was determined in physiological saline, and compressive strength and Young's modulus of the samples were measured. The ability of hydroxyapatite formation was investigated in simulated body fluid (SBF) and cytotoxicity of the particles was evaluated in contact with human bone marrow stem cells. The results of this study showed that Willemite nanobioceramic is obtained with the expected chemical composition and negative zeta potential. The results also showed that the hydroxyapatite forming ability in SBF was not strong. MTT assay confirmed the cell proliferation and availability in contact with a specific concentration of Willemite nanoparticles. All these findings indicate that Willemite nanobioceramic with proper biocompatibility can be suggested as a novel biomaterial for the repair of bone defects.

In this study, the effect of nano-titania addition on the mechanical strength of mullite-bonded alumina-siliconcarbide nano-composites was investigated. To this end, the gel-casting process via nano-silica sol was used for shaping the nano-composite.The firing temperature of composition was determined by use of STA. The compressive and bending strengths of samples were measured after firing at 1300 °C. Besides, the physical properties, phase composition and microstructure of the composites were evaluated after firing. The results showed that the use of nano-titania up to 1 wt.% had a higher effect on improvement of nano-composite mechanical strength. The nano-titania addition led to increasing of mullite phase and higher growth of its needle-like grains. Enhancing of ceramic bonds between grains and the improvement of mechanical strength were obtained by increasing the mullite phase.

Bio-inspired silver nanoparticles were synthesized with the aid of a novel method, using leaves of the plant Nigella sativa. After drying the leaves in air, they were first sweltered in boiling distilled water and the liquid was filtered subsequently. The result was the brothused to reduce solutions including various concentrations of silver nitrate in a proper amount of pH. The displayed UV–visible spectra identified formation of silver nanoparticles whenever the colorless initial acclimated mixture turned brown. The centrifuged powder samples were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (FESEM) and energy dispersive X-ray diffraction analysis (EDX) methods. The results clearly revealed that the final particles of precipitated powder are high purity agglomerates of silver nanoparticles. Besides, the effects of various amounts of the silver salt on particle size of nano silver were studied, using a particle size analyzer. FTIR results also indicated the role of different functional groups in the synthetic process.

In this study, NBG was successfully achieved through a sol-gel technique, and to further improve its dispersibility, a crylate coupling agent was coupled onto the surface of the NBG. The 3-(Trimethoxysilyl)Propylmethacrylate coupling agent was used to the surface modification of the synthesized NBG by a wet-chemical method in a dynamic inert nitrogen atmosphere. The surface properties of the biomaterials before and after modification were characterized and compared using FTIR and AFM techniques. The characteristic peaks in FTIR spectra indicated that –CH2, –CH3 and C=O groups appeared on the surface of modified NBG, and also, AFM analysis revealed that the dispersibility of surface modified NBG was improved, significantly. The above results proved that the desired groups of 3-(Trimethoxysilyl)Propyl methacrylate had been covalently bonded onto the surface of NBG. Besides, a nanocomposite scaffold was synthesized using the synthesized NBG and polyurethane foam as raw materials. The morphology of pores, porosity contents, compress strength and bioactivity of the scaffold were studied. The results showed that the biological scaffolds for use in bone tissue engineering with the basic requirements (90% porosity and 200-600 μm pore diameter) were successfully prepared. The polymer component had no effect on the relationship between the scaffold pores and bioactivity of bioglass nanoparticles. Improvement of compressive strength and proper bioactivity of the resulted scaffold showed that it is an acceptable candidate for biomaterials applications.

The aim of the present study is to study the effects of adding  diopside (CaMgSi₂O₆) as well as silica sulfuric acid nanoparticles to ceramic part of glass ionomer cement (GIC) in order to improve its mechanical properties. To do this, firstly, diopside (DIO) nanoparticles with chemical formula of CaMgSi₂O₆ were synthesized using sol-gel process and then, the structural and morphological properties of synthesized diopside nanoparticles were investigated. The results of scanning electron microscopy (SEM) and particle size analyzing (PSA) confirmed that synthesized diopside are nanoparticles and agglomerated. Besides, the result of X-ray diffraction (XRD) analyses approved the purity of diopside nanoparticles compounds. Silica sulfuric acid (SSA) nanoparticles are also prepared by chemical modification of silica nanoparticles by means of chlorosulfonic acid. Fourier transform infrared spectroscopy (FTIR) technique was used to find about the presence of the (SO₃H) groups on the surface of silica sulfuric acid nanoparticles. Furthermore, various amounts (0.1, 3 and 5 wt.%) of diopside and silica sulfuric acid nanoparticles were added to the ceramic part of GIC (Fuji II GIC commercial type) to produce glass ionomer cement nanocomposites. The mechanical properties of the produced nanocomposites were measured using the compressive strength, three-point flexural strength and diametral tensile strength methods. Fourier transform infrared spectroscopy technique confirmed the presence of the (SO₃H) groups on the surface of silica nanoparticles. The compressive strength, three-point flexural strength and diametral tensile strength were 42.5, 15.4 and 6 MPa, respectively, without addition. Although adding 1% silica solfonic acid improved nanocomposite mchanical properties by almost 122%, but maximum increase in nanocomposite mechanical properties was observed in the nanocomposites with 3% diposid, in which 160% increase was seen in the mechanical properties.