Sharif Digital Repository

A biocompatible ferrofluid have been prepared by co-precipitation of FeCl2.4H2O and FeCl3.6H2O under ultrasonic irradiation and with NaOH as alkaline agent. Also cystein was used as capping agent in the solution. Magnetic properties of the produced ferrofluid then determined by VSM test and magnetite nanoparticles were characterized by XRD and TEM techniques. Results indicate the presence of a biocompatible superparamagnetic ferrofluid including magnetite nanoparticles with particle size ranging under 15 nm. The effect of ultrasonic irradiation on presence of a sharp particle size distribution then denoted by comparing the condition with production without ultrasonic irradiation  

In this study magnetite nanoparticles were synthesized by microemulsion and were coated with TiO2 by a precipitation technique. The synthesize process were done under fixed molar ratio of various constituents of microemulsion and molar ratio of water to oil. Results of X-ray diffraction spectroscopy (XRD) showed that the uncoated nanoparticles were consisted of magnetite as the major phase and no other detectable phases such as pure iron or hematite were found. Field emission scanning electron microscopy (FE-SEM) results showed that the synthesized nanoparticles small size and narrow particle size distribution. For TiO2 coating process the effect of TBOT concentration, water concentration,... 

Heavy metals, present in many industrial wastewaters, are considered as major pollutants of environment. Various methods to removal heavy metals effectively from effluents have been used in industry, yet more efficient and economical methods are required. Magnetic iron nanoparticles are known for their superior adsorption, ion exchange and electro-static forces characteristics.The aim of this study was to evaluate the efficiency of magnetic nanoparticles for removal of hexavalent chromium (VI) and Divalent nickel from wastewater and the parameters that influence the removal.The magnetite nanoparticles were prepared by co-precipitation method where produced Fe3O4 nanoparticle’s average size... 

Ferrofluids are special stable suspensions of magnetic nanoparticles dispersed in liquid phase. These materials have numerous biological applications such as drug delivery, magnetic hyperthermia and magnetic resonance imaging due to their special magnetic properties and fluidity. Particle size and magnetic properties of ferrofluids have an important role in these applications. In this work, magnetite-based ferrofluids have been synthesized via coprecipitation and hydrothermal methods. In the coprecipitation process, cysteine and dextran surfactants have been used as ferrofluid stabilizer and effect of synthesize temperature, time, pH and surfactant concentration have been investigated on... 

In this research Fe3O4 magnetic nanoparticles were prepared. To protect against oxidation, a shell of SiO2 was deposited on Fe3O4. Graphene oxide was prepared by the modified Hummer method and supported on the Fe3O4@SiO2 core-shell. Then, ionic liquid layer was impregnated on it. Afterward, PtAu nano alloy were synthesized on the surface of nanocomposite with the different molar ration including 100:0, 75:25, 50:50, 25:75 and 0:100. The as-prepared nanocomposite was characterized by SEM, XRD, and FT-IR analytical methods.For investigation of kinetically activity of catalysts, reduction of 4-nitrophenol with NaBH4 as reducer was used. The adsorption in different times was obtained by UV-vis... 

Superparamagnetic core/shell nonporous (S1) and core/shell/shell mesoporous (S2 and S3) nanocomposite magnetite/silica particles with a magnetite cluster core of 130±30 nm, a nonporous silica shell of 90±10 nm thickness, and a mesoporous silica shell of 70±15 nm thickness were prepared thorough a simple method. Mesoporous particles were prepared with two BJH pore sizes (2.44 for S2 and 3.76 nm for S3 particles, respectively). The fabricated S1, S2 and S3 particles present high saturation magnetization values of 20, 13 and 17 emu/g, respectively. As a biological application, the lipase from Pseudomonas cepacia was successfully immobilized onto the amino-functionalized nanocomposite particles... 

In this research, immobilization method was employed to increase the thermal stability of Chondroitinase ABC I (cABC I) enzyme. In first step, magnetite nanoparticle (Fe3O4) was selected as a support and cABC I enzyme was attached via the adsorption method. The results showed that pH=6.5, temperature 15 ˚C, enzyme-to-support mass ratio 0.75, and incubation time 4.5 hr were the appropriate conditions for immobilizing cABC I enzyme on Fe3O4 nanoparticle. It was also found that the optimum pH for free and immobilized enzymes was 7.6 and 8.0, respectively. The maximum activity of free enzyme was obtained at 25 ˚C, whereas the activity of immobilized enzyme was almost constant in the temperature... 

In this research, a facile, two-step synthesis was reported for 34-LCysteine- nanocomposites. The first step comprises the preparation of LCysteine functionalized magnetic nanoparticles (MNPs) core-shell structures via co-precipitation method. In the second step, graphene quantum dots (GQDs), which were synthesized by citric acid carbonization, added to the functionalized MNPs and finally refluxed at the appropriate time and temperature. LCysteine as a biocompatible, natural amino acid were used to link MNPs with GQDs. This nanocomposite was characterized by various techniques. XRD and FT-IR were used to investigate the formation of MNPs and LCysteine existence on the MNPs surface. XPS... 

The use of magnetic nanoparticles modified with proper surface agent and the ability of controlling by magnetic field, that can induce colloidal stability, is considered as a vector to transfer DNA plasmid, or pDNA in short, in the field of gene therapy. In thiss research, pH-responsive dextran-based magnetic nanogels (dextMNGs) were synthesized via inverse mini-emulsion method. Fourier transformation infrared spectroscopy (FTIR) showed that magnetite nanoparticles (MNPs) were successfully modified with arginine and had amine terminals. FTIR, also, proved that aldehyded dextran was crosslinked by arginine modified magnetite nanoparticles (RMNPs) via pH sensitive imine bonds. X-ray...