Papers by Keyword: Superparamagnetic

Abstract: Local hyperthermia therapy is one of the cancer treatments by implementing heat from a temperature of 41-45°C on cancer cells. This method is believed to reduce the risk of normal cells around the cancer cells from dying. The form of hyperthermia therapy itself is in ferrofluid. During its development, superparamagnetic nanoparticles of iron oxide have attracted various studies because of their good magnetic properties and good biocompatibility. However, the poor particle interactions and their tendency to aggregation make coatings on superparamagnetic necessary. Therefore, silica coating on the superparamagnetic surface is carried out to reduce the risk of aggregation and increase the biocompatibility of the material. Polyethylene glycol functionalization was also applied to improve the biocompatibility of the material, as well as being a carrier for ferrofluid. The test was carried out using the magnetite co-precipitation synthesis method and the formation of a sol-gel silica coating. Variations applied in this experiment are the effects of TEOS concentration as a source of silica and the ratio of particles to PEG. The addition of silica was proven to increase the value of the magnetic moment to 51.55 emu/g. The addition of TEOS as a source of silica in iron (III) nanoparticles has an effect on increasing the magnetic attraction, decreasing the surface tension value, reducing particle size, and decreasing the SAR value. Functionalization of polyethylene glycol has the effect of reducing the magnetic moment, increasing and decreasing hydrophobicity, increasing the surface tension value, and reducing the particle size of iron (III) oxide nanoparticles. This shows that magnetic nanoparticles coated with silica with polyethylene glycol functionalization are proven to generate heat when given AC current with the SAR value and the highest temperature is found in iron (III) oxide which gets 3ml silica coating with a PEG ratio of 2:5 at a temperature of 32.2°C. and SAR value of 87.63 W/mg

Abstract: The Mn_0.3Fe_2.7O₄/PEO/PMMA/AC nanocomposites were synthesized using co-precipitation and solid-state reaction methods. The Mn_0.3Fe_2.7O₄/PEO/PMMA/AC nanocomposites were success formed. This was confirmed by characterization using FTIR instrument. The Fe-O, C-O, and C-H₂ functional groups were the representation of Mn_0.3Fe_2.7O₄, PEO/PMMA, and AC respectively. Investigation of crystal structure was characterized using XRD instrument. According to X-Ray Diffraction analysis, the crystal size was 10.82 nanometers and the peak of AC was detected on 2θ around 24.85^o. In addition, the investigation of magnetic properties was characterized using VSM instrument. This result showed that the Mn_0.3Fe_2.7O₄/PEO/PMMA/AC nanocomposites behave as a superparamagnetic material with a saturation magnetization value was around 12.55 emu/gram.

Abstract: The recent development of the using the magnetic nanoparticles for hyperthermia treatments emphasizes the needed of smart materials to become a safety for heat therapy. Self-regulate magnetic nanoparticles of MnZnFe₂O₄ may be proper for thermal treatments. Structure and magnetic properties of the synthesis Mn_1-xZn_x Fe₂O₄ with x=0- 0.5 by step 0.1were studied. Superparamagnetic nanoparticles of MnZnFe₂O₄ were prepared by co-precipitation method, followed that heat treatment in the autoclave reactor. XRD results showed that is difficult to prepare MnZnFe₂O₄ directly using the co-precipitation method. Preparation method yield nanoparticles with spherical shape and there is a slight change in the particle size distribution, also observed shrinkage occurs in the particle size after heat treatments, the average particle size was estimated about 20nm as confirmed by FESEM images. FTIR spectra of samples showed two distinct absorption peaks in the range ~ 617 – 426 (cm^-1) related to stretching vibrations of the (Fe-O) in the tetrahedral and octahedral side respectively. Magnetic measurements were carried out using (VSM), M-H curves indicate typical soft magnetic materials and particles so small to be identical superparamagnetic nanoparticles. Heating ability of water based colloidal dispersions of samples were studied under magnetic field strength 6.5kA/m and the frequency 190 kHz, and the results showed when increasing Zn²⁺ to x=0.3 or more the samples not heated up. Depending on the heating curve susceptibility, effective relaxation time 𝜏 and Néel relaxation time , were determined.

Abstract: Magnetite nanoparticles have been successfully prepared by hydrothermal method from FeCl₃ as starting material. The properties and morphology of the products with different synthesis time and FeCl₃ concentration were investigated. Firstly, the FeCl₃ with concentration of 0.05 – 0.15 M and 0.10 M sodium citrate as well as 0.15 M were mixed with distilled water containing 0.1 g polyethylene glycol. Subsequenly, the solution was transferred into a Teflon-lined autoclave and it heated into an oven at 210°C for 12 hours. The black precipitate that formed was separated by a bar magnet, then washed with water and ethanol, and dried at 60°C overnight. The magnetite formation begun at 3.5 hours synthesis time with crystal diameter in range of 9.4-30 nm. The crystallinity and crystal size of magnetite increased with reaction time and concentration of FeCl₃. The magnetite nanoparticles had a mesoporous structure and bigger pores at higher concentration. The saturation magnetization (Ms) of magnetite was in the range of 59 – 81 Emu/g with coercivity value was near to zero showing that magnetite nanoparticle had superparamagnetic properties.

Abstract: The size effect of magnetic nanoparticles provides a various magnetic characteristic as a change of domain size. We report, synthesis of core-shell iron oxide and magnetic properties. Iron oxide particles were synthesized by co-precipitation method of iron (III) FeCl₃.6H₂O, iron (II) FeCl₂.4H₂O, in the mixture of with or without TEOS to investigated the physical properties. From XRD measurement, it was observed that all iron oxide particles with or without mixture of SiO₂ has a hematite phase of a-Fe₂O₃. From M-H loop measurement, it was observed that the iron oxide without SiO₂ has a ferromagnetic characteristic, while the iron oxide with SiO₂ showed a medium state as a contribution of superparamagnetic and ferromagnetic properties.

Abstract: Superparamagnetic iron oxide nanoparticles (SPION) were synthesized by one pot coprecipitation method at room temperature in the presence of Polyvinylpyrrolidone (PVP). X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Vibrating Sample Magnetometer (VSM) were used to analysis the physicochemical properties of PVP-SPION. The XRD patterns confirmed that the structure of as-synthesized sample is magnetite with cubic structure system. In TEM results, the image of PVP-SPION displayed that the size of particles was 14.05 nm with narrower size distribution and also the PVP played important role to minimize the agglomeration of SPION. Finally, the high saturation magnetization value of PVP-SPION (53.0 emu/g) indicate the as-synthesized sample has a great potential as a contrast agent for MRI.

Abstract: Monodisperse nanoparticles are materials that are not agglomerate. The good characteristic of these materials is the dispersity in water, so they can better react with target pollutants. Accordingly, in this work, the monodisperse magnetite nanoparticles with the superparamagnetic property were synthesized and characterized. The hydrothermal method with the iron compound and polymer as precursors was conducted. The magnetic nanoparticles were characterized by several techniques including X-ray diffraction, field emission scanning electron microscope, transmission electron microscope, and vibrating sample magnetometer. The saturation magnetization (Ms) value, the coercivity (Hc), and the retentivity (Mr) were measured to demonstrate the paramagnetic behavior of the monodisperse magnetite nanoparticles. The results showed that the Fe₃O₄ nanoparticle were obtained at 200 °C for 16 h. The particles are monodispersed with the size approximately in the range of 60 - 250 nm as confirmed by FE-SEM and TEM images. These are the single grain and had the spherical shape similar to a blackberry. The saturation magnetization of 17.287 emu/g and ratio of retentivity to saturation magnetization (Mr/Ms) characterized the squareness of the hysteresis loops was 0.03653. It can be indicated that the Fe₃O₄ nanoparticles had superparamagnetic behavior. This property of Fe₃O₄ nanoparticles can draw pollutants to absorb on the surface of these nanomaterials. Then adsorbed pollutants can be easily removed by separating the Fe₃O₄ materials from water. This technique can be applied further in water treatment and pollutant removal.

Abstract: It has been studied the fabrication of a sheet made of polyvinyl alcohol (PVA) fibers loaded with Fe₃O₄ nanomagnetic materials using an electrospinning technique. The solution for the electrospinner was prepared by stirring nano powder of Fe₃O₄ with a solution of 10% PVA in water at room temperature. The electrospinning process was done under fixed of 15 kV DC voltage, using 12 cm distance between the electrodes, and using a syringe needle having a diameter of 0.4 mm. The morphology of fibers was tested using scanning electron microscope (SEM), while the size of particles was tested using transmission electron microscope (TEM). Moreover, the crystallinity of fibers was tested using Laue and x-ray diffraction, while the magnetic moment was tested using a vibrating sample magnetometer (VSM). The result shows that the PVA sheet composing of fibers having a diameter in the range of 130 mm to 250 mm, accommodating Fe₃O₄ nano particles in the range of 15 mm to 25 mm, indicating a partial superparamagnetic property.

Abstract: Mesoporous maghemite γ-Fe₂O₃ was obtained by thermal decomposition of iron citrate xerogel hydrate. The influence of precursor molar concentration and calcination temperature on the material phase composition, morphology, crystalline and magnetic microstructure, surface condition and optical properties was studied. The model of mesoporous γ-Fe₂O₃ formation is proposed. Obtained maghemite was tested as cathode material for lithium power sources. Increase of lithium power sources specific capacity and energy with the samples specific surface area enlarging is determined. Two kinetic processes are observed during discharge processes: lithium accumulation at the cathode material/electrolyte interface and diffusion of lithium ions into the material crystal structure. The diffusion coefficients of lithium in the cathode material on the different stages of discharge process are calculated.

Abstract: The design, synthesis and characterization of magnetic-luminescent nanoparticles is now more and more studied since the last decade. However, optimizing the design of such materials requires a deep understanding of their physico-chemical properties. In this paper are reported extended investigations on luminescent and magnetic @SiO₂ Nps prepared by a water-in-oil microemulsion technique. The Cs₂[Mo₆Br₁₄] cluster compound is used as red-NIR phosphor and is prepared by solid state chemistry. We bring here new insights into the structure of such Nps and its interplay with their optical or magnetic properties.