Nguyen Chi Thuan

Magnetic fluid based on Fe3O4 nanoparticles: Preparation and hyperthermia application

The paper presents results of research on preparing the magnetic fluid based on Fe3O4 nanoparticles and its potential hyperthermia application. Magnetic fluids were manufactured by dissolving superparamagnetic nanoparticles coated by suitable biocompatible starch layer during the co-precipitation processing. The coated particle size changes in range of 15÷17 nm were characterized by FESEM images. At room temperature, the samples exhibit super-paramagnetic behaviour with a saturation moment of 65 emu/g. The concentration of magnetic nanoparticles contained in carried liquid reach to 15 mg/ml. The magnetic fluid was used as a mediator for heating by an AC magnetic field with the frequency of 184 kHz and field strength of 12 kA/m. The dependence of heating on nanoparticle concentration was observed and it implied that the magnetic fluid is a suitable mediator for cancer treatment by hyperthermia application with appropriate controlling the heating temperature ranges from 45 to 50°C.

Invitro toxicity test and searching the possibility of cancer cell line extermination by magnetic heating with using Fe3O4 magnetic fluid

A Fe3O4 based magnetic fluid with different concentrations ranged between 0.15 ng/cell to 10 ng/cell (nano gram/cell) was used in the in vitro toxicity test on several cancer cell lines, Sarcoma 180, HeLa and H358. It shows that the fluid with a concentration of Fe3O4 below 1.2 ng/cell is completely non-toxic for these cell lines. Even through in the presence of the highest concentration of 10 ng/cell, the cell viability still reaches more than 60%. The magnetic fluid with Fe3O4 concentration of about 0.1 ng/cell was also used to search ex-vivo the possibility of Sarcoma 180 extermination by magnetic heating with an AC field of 120Oe and 184 KHz. The result shows that after a heat treatment for 30 min., 40% of Sarcoma 180 cells was killed.

Magnetic memory effect in a strong phase competition system La0.7Ca0.3Mn0.925Ti0.075O3

A magnetic memory effect was observed by means of zero-field-cooled magnetization measurements in a temperature range below TC. The magnitude of magnetic memory effect, determined by the difference between the magnetization curve with a pause of temperature during the cooling process and its reference curve without the pause, showed that it is independent of the number of pauses. The memory effect is supposed to be related to the isolated states with an infinite degeneration, which is associated with the presence of magnetic frustration in a system with a strong magnetic phase competition. Besides, a resistance memory effect was concomitantly observed at the same pause temperatures.

TiO2/Co nanomaterials: synthesis and properties

The formation of anatase phase of TiO2 was observed and evaluated by using X-ray diffraction and Raman scattering spectra. It was found that the annealing temperature, its temperature rate and Co doping strongly increase the formation velocity of the anatase phase and size of TiO2 nanoparticles. The creation of Co cluster in TiO2 thin film was also estimated by using X-ray diffraction and magnetic characterisation in a combinative study. It was found that the annealing temperature remarkably affects the creation of the Co cluster in TiO2 thin films.

CIP spin torque effect in the spin valve pinned with an oxide antiferromagnetic layer

Spin valve Ni0.85Co0.15O/Co85Fe15/Cu/Co85Fe15 was manufactured by a RF magnetron sputtering system. M(H) and R(H) characteristics of the spin valve were measured in CIP configuration at room temperature has a magnetoresistance ratio of about 8% and a high exchange bias at room temperature. The current density and angle between the applied magnetic field and injection current were changed in an aim to observe their effects on MR and exchange bias of the spin valve. The current density and angle strongly affect MR and exchange bias. Both MR and exchange bias clearly decrease in dependence of the current density and direction of the magnetic field. It is supposed to be related with a current-induced spin torque in device.