فهرست مطالب b. aslibeiki

Spinel ferrites nanoparticles are among the most important magnetic materials and their applications in ‎different areas have increased significantly in the last two decades. The idea of using ferrites ‎nanoparticles in medical applications, caused attraction of attention of researchers in worldwide to this field ‎and increase number of studies on the subject. The increase of the magnetic resonance imaging (MRI) contrast is one ‎of the most important medical applications of spinel ferrite nanoparticles. The imaging results of ‎live organisms show that the spinel ferrite nanoparticles can increase the contrast of images of ‎cancerous cells and therefore help tumors diagnosis. Magnetic hyperthermia is another ‎application of spinel ferrite nanoparticles, in which several factors affect the specific adsorption ‎rate and efficiency of the method. However, this method has not yet been applied to human kind, ‎and it is being studied in laboratories on animals like mouse etc. Targeted drug delivery is the ‎third application of spinel ferrite nanoparticles in the field of medicine. This method is one of the ‎most advanced treatment routes. In this method, several parameters must be considered to ‎achieve the best results. Considering the importance of health and treatment, the main purpose of ‎this review is to give the latest results of studies on the three mentioned methods on using the ‎spinel ferrite nanoparticles for medical purposes‎.

Studies show that the size of magnetic nanoparticles has an important impact on their properties. So, the possibility of an optimal size for their use in medical applications has been reported. Therefore, in this study, cobalt ferrite nanoparticles were prepared using co-precipitation method  at 80°C; then the powder was annealed  in a furnace at 150, 200, 300, 400, 500 and 600°C to obtain nanoparticles with different sizes. The X-ray diffraction patterns confirmed the formation of a pure spinel phase in the nanoparticles, and the average size of the  crystalites of the samples was determined by Scherrer's formula  to be  8.18, 9.04 , 8.95, 9.55, 10.40 and 11.12 nm for synthesized samples at 150 to 600°C, respectively. Measurements of magnetic properties also indicated an increase in the field and the saturation magnetization by enhancing the size. The heat generation  efficiency of the nanoparticles suspension was measured by the application of an alternating magnetic field at 92 kHz and the temperature increase curve was calculated versus time. These experiments showed that the highest value of specific adsorption rate for nanoparticles of about 9 nm, and particles larger or smaller than that amount led to a smaller absorption rate. The results of this study, suggest an optimal size for hypertherma applications in which the highest thermal efficiency is achieved.