Sharif Digital Repository

TiO2 nanostructures with different morphologies (spherical, tube, leaf-like and flower-like particles) were synthesized via a facile hydrothermal process. Polycaprolactone (PCL)/10 vol.% TiO2 nanocomposites were prepared by solvent casting methods. In vitro bioactivity of the nanocomposite films was examined by immersion in the simulated body fluid (SBF) for up to 28 days. It was found that the morphology of titania nanostructures significantly influence the in vitro bioactivity of PCL/TiO 2 nanocomposites. This observation was attributed to the amount of anatase phase and the specific surface area of the TiO2 nanostructures, which provide high surface exposure to SBF  

The effects of six synthetic imidazolium-based ionic liquids (ILs) on the CuII-catalyzed chemiluminescence of lucigenin (Luc-CL) in the pH range 6.0-11 were investigated. Preliminary experiments found that the CL emission was strongly enhanced or inhibited in the presence of the ILs. The degree of enhancement or inhibition of the CL intensity in the presence of each IL was related to the molecular structure of the IL, the medium used, and the pH. The maximum enhancement of the CL intensity was observed at pH 9.0 (amplification factor=443). This decrease in the pH at which maximum CL enhancement occurred and the substantial signal amplification of the Luc-CL may be related to a strong... 

Ultrafiltration membranes were prepared from blend of the poly(vinylidene fluoride) (PVDF) with polyacrylonitrile (PAN) via phase inversion method induced by immersion precipitation. N,N-dimethylacetamide (DMAc) and water were used as solvent and coagulant (non-solvent), respectively. The effect of blending ratio on the morphology and antifouling behavior of the prepared membranes was investigated. The performance of the membranes was evaluated by using cross flow filtration of pure water and buffered bovine serum albumin (BSA) solution as feed. Contact angle measurements indicated that the hydrophilicities of the PVDF/PAN membranes increased by increasing PAN concentration in the casting... 

We present a universal model of brain tissue microstructure that dynamically links osmosis and diffusion with geometrical parameters of brain extracellular space (ECS). Our model robustly describes and predicts the nonlinear time dependency of tortuosity (λ=D/D∗) changes with very high precision in various media with uniform and nonuniform osmolarity distribution, as demonstrated by previously published experimental data (D = free diffusion coefficient, D∗ = effective diffusion coefficient). To construct this model, we first developed a multiscale technique for computationally effective modeling of osmolarity in the brain tissue. Osmolarity differences across cell membranes lead to changes... 

Two non-ionic and hydrophilic surfactant additives, Tetronic-1107 and Triton X-100, were added to poly(vinyl chloride)/NMP polymeric solution to prepare ultrafiltration membranes via immersion precipitation. Surfactants at three different weight percentages up to 6 wt% were added, and the fabricated membranes were characterized and their performance for water treatment in the presence of bovine serum albumin (BSA) as a foulant was assessed. The scanning electron microscopy images indicated remarkable changes in morphology due to higher thermodynamic instability after surfactant addition. The membranes are more porous with more macro-voids in the sub-layer. Plus, the membranes become more... 

Ultrafiltration membranes were prepared from blend of the poly(vinylidene fluoride) (PVDF) with polyacrylonitrile (PAN) via phase inversion method induced by immersion precipitation. N,N-dimethylacetamide (DMAc) and water were used as solvent and coagulant (non-solvent), respectively. The effect of blending ratio on the morphology and antifouling behavior of the prepared membranes was investigated. The performance of the membranes was evaluated by using cross flow filtration of pure water and buffered bovine serum albumin (BSA) solution as feed. Contact angle measurements indicated that the hydrophilicities of the PVDF/PAN membranes increased by increasing PAN concentration in the casting... 

In theory, diffusion and perfusion information in MRI maps can be combined to yield morphological information, such as capillary density, volume and possibly capillary plasma velocity. This paper suggests a new method for determination of mean radius, length and capillary density in normal regions using diffusion and perfusion MRI. Mean Transit Time (MTT), Cerebral Blood Volume (CBV), Apparent Diffusion Coefficient (ADC), pseudo-diffusion coefficient (D*) and ΔR2 and ΔR2* values were utilized to calculate mean radius, length and capillary density. To verify the proposed theory, a special protocol was designed and tested on normal regions of a male Wistar rat using obtained functions. Mean... 

Convenient medical diagnostics and treatments can replace conventional healthcare procedures because of their fast and profitable applications with reduced infection risk. Meanwhile, early diagnosis of cancer is a leading research subject due to the high fatality rate of the disease and being a vital precursor in the treatment effectiveness. Electrochemical-based micro-biosensors are the best candidates for measuring particular biomarker concentrations in body fluids. To address this need, we used a simple fabrication approach to develop an effective immunosensor for the early detection of cancer, in particular prostate cancer. The carbon fibers, obtained from the electrospinning technique,... 

Finite element analysis is an effective tool to evaluate the material properties of living tissue. For an interactive optimization procedure, the finite element analysis usually needs many simulations to reach a reasonable solution. The metamodel analysis of finite element simulation can be used to reduce the computation of a structure with complex geometry or a material with composite constitutive equations. The intervertebral disc is a complex, heterogeneous, and hydrated porous structure. A poroelastic finite element model can be used to observe the fluid transferring, pressure deviation, and other properties within the disc. Defining reasonable poroelastic material properties of the... 

Nanostructured copper-doped uorapatite (Cux.Ca(10X).(PO4)6.F2) having crystallite sizes of 19, 29, and 34 nm at x = 0:9, 0.4, and 0.0, respectively, was synthesized by planetary ball milling of CaO, P2O5, CaF2, and CuO powders. Specifications of the products were determined by Fourier-transform infrared spectroscopy, eld emission scanning electron microscopy, transmission electron microscopy, and X-ray di raction analyses. In-vitro studies and Mossman's Tetrazole Test (MTT) assays were also conducted by incubating Cux.Ca(10X).(PO6).F2 powder into Kokubo's Simulated Body Fluid (SBF) and against BT-20 cell, respectively, to determine bioactivity and biocompatibility of the materials.... 

Thermoplastic starch (TPS), as a natural based polymer, is known to have the capability to be used in biological applications due to its biocompatibility and biodegradability. In this study, mechanical properties of TPS are enhanced by incorporating bioactive β-tricalcium phosphate (β-TCP) particles for bone tissue engineering applications. Starch-based nanocomposites containing 3, 5, and 10 wt% of β-TCP nanoparticles (TT3, TT5, TT10) were made using a co-rotating twin-screw extruder. Dynamic light scattering (DLS) and X-ray diffraction (XRD) techniques were employed to analyze the nanocomposites. Moreover, degradability, swelling degree, and biomineralization in a simulated body fluid (SBF)... 

To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid... 

To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid... 

To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid... 

Poly (lactate-co-glycolate) (PLGA) is a typical biocompatible and biodegradable synthetic polymer. The addition of TiO2 nanoparticles has shown to improve compressive modulus of PLGA scaffolds and reduced fast degradation. A novel method has been applied to fabricate PLGA/TiO2 scaffolds without using any inorganic solvent, with aim of improving the biocompatibility, macroscale morphology, and well inter-connected pores efficacy: Air–Liquid Foaming. Field Emission Scanning Electron Microscopy (FESEM) revealed an increase in interconnected porosity of up to 98%. As well the compressive testing showed enhancement in modulus. Bioactivity and in vitro degradation were studied with immersion of... 

In this study, different concentrations of ascorbic acid (50, 100 and 200 μg/mL) were added to the liquid phase of a calcium phosphate cement (CPC). The cements were immersed in simulated body fluid (SBF) for different intervals and physical, physicochemical and mechanical properties of them were evaluated. The release of added ascorbic acid from CPCs into the SBF solution was also studied. From the results, both setting time and injectability of CPC decreased by adding ascorbic acid, however the compressive strength was sharply increased before soaking in SBF solution. But, the compressive strength values of all cements (with or without ascorbic acid) soaked in SBF solution for more than 7... 

In the first stage, chitosan (CH)-hydroxyapatite (HA)-multiwalled carbon nanotube (MWCNT) composite coatings were synthesized by electrophoretic deposition technique (EPD) on 316L stainless steel substrates at different levels of pH and characterized by X-ray diffraction (XRD), Raman spectroscopy, FTIR and field emission scanning electron microscopy (FESEM). A smooth distribution of HA and MWCNT particles in a chitosan matrix with strong interfacial bonding was obtained. In the next stage, effects of pH and MWCNT content of the suspension on the corrosion behavior and deposition mechanism were studied. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) curves... 

The present work studied bioactive coatings on the surface of ceramic biomaterials. Zirconia toughened alumina (ZTA) composites containing 15 mol.-%. Partially stabilised zirconia was prepared after 1 h sintering at 1550°C. Apatite layers were then coated onto the surfaces of composites by the biomimetic method using 1·5-2 multiply concentrations of simulated body fluid (SBF). Before treatment in SBFs, a sodium silicate layer was employed as nucleating agent to induce the formation of a calcium phosphate layer. The effect of immersion time on the morphology of the precipitate was monitored with a scanning electron microscope. X dot maps revealed that there is a relationship between... 

Hydroxyapatite (HA) is the most substantial mineral constituent of a bone which displays splendid biocompatibility and bioactivity properties. Nevertheless, its mechanical property is not utmost appropriate for a bone substitution. Therefore, a composite consist of HA and a biodegradable polymer is usually prepared to generate an apt bone scaffold. In the present work polycaprolactone (PCL) was employed as a matrix and hydroxyapatite nanorods were used as a reinforcement element of the composite. HA/PCL nanocomposites were synthesized by a new in-situ sol-gel process using low cost chemicals. Chemical and physical characteristics of the nanocomposite were studied by X-ray diffraction (XRD),... 

The low erosion resistance of titanium and its alloys has prevented their widespread application as joint implants. In addition, one essential requirement for the implants to bond with the living bone is the formation of a bone-like apatite on their surfaces in the host body. To enhance the erosion resistance of the surface, a diffused layer of TiB2 was formed at 1000uC on the commercial pure titanium. Hydroxyapatite was then coated on the boronised titanium by means of dip coating in a sol-gel solution. In order to confirm the biocompatibility of the specimens, they were soaked in a simulated body fluid for several days. The surface morphology of the specimens after exposure was studied by...