Biyomedikal Uygulamalar için Yüksek Verimli CoFe Nanoparçacıkları

Abstract

One of the most common diseases of our era, cancer, is treated using methods such as chemotherapy, radiation therapy and surgery. However, these conventional methods also cause damage to healthy tissues along with tumor tissue. This challenge has increased interest in alternative treatment approaches for cancer. Magnetic hyperthermia is a method that can enhance the effectiveness of chemotherapy and radiation therapy in cancer treatment. Superparamagnetic iron oxides are frequently preferred for magnetic hyperthermia applications. However, the low saturation magnetization of superparamagnetic iron oxides limits their efficiency in magnetic hyperthermia applications. CoFe nanoparticles, with their high saturation magnetization, low coercivity, and high Curie temperatures are suitable materials for efficient use in magnetic hyperthermia applications. However at the nano scale, CoFe nanoparticles are not stable and oxidize rapidly. Additionally, CoFe nanoparticles can exhibit toxic effects in the body. These problems can be solved by coating the nanoparticles with a suitable material. In this context, this thesis study aimed to produce graphitic shell-coated CoFe nanoparticles that can be used with high efficiency in magnetic hyperthermia applications. CoFe nanoparticles were synthesized by alloying Co and Fe powders in equiatomic ratios through mechanical milling. The mechanical milling process was carried out for different durations ranging from 2 to 40 hours to obtain CoFe nanocrystals of different particle sizes. The produced powders were then milled again with graphite powder and subjected to heat treatment in a vacuum environment at 600 °C to produce graphitic shell-coated powders. Structural analysis of the samples was performed using X-ray diffraction, scanning electron microscope and Raman spectroscopy. The magnetization measurements of the samples were carried out at room temperature using a vibrating sample magnetometer with an applied external magnetic field of ±3 T. The synthesized samples were found to have high saturation magnetization (~200 emu/g) and low coercivity (<80 Oe), indicating soft ferromagnetic properties. The magnetic hyperthermia efficiencies of the as-produced samples were investigated by specific absorption rates calculated from the magneto-thermal measurements. The highest specific absorbtion rate for CoFe nanocrystals was calculated as 271±16 W/g for powders with an average crystalline size of 12.4 nm. The highest SAR for the graphitic shell-coated CoFe nanocrystals was calculated as 125±3 W/g for powders with an average crystalline size of 28.1 nm. These results demonstrate that graphitic shell-coated CoFe nanocrystals are efficient candidates for magnetic hyperthermia applications.