Ferrite nanoparticles doped with nickel, zinc, and cobalt were synthesized and coated with triethylene glycol (TREG), polyethylene glycol (PEG), and silica for their applications to magnetic hyperthermia and MRI contrast agents. These particles were characterized by various analytical tools. The crystalline structure, shape and size distribution, coating status, and magnetic properties were investigated by using X-ray diffraction (XRD), transmission electrum microscope (TEM), Fourier transform infrared (FT-IR), and vibrating sample magnetometer (VSM), respectively. The heating capability of these particles in the aqueous solution was tested by using an induction heating system. Some nanoparticles’ ability to enhance the relaxation process of hydrogen protons in the aqueous solution were also tested by using an MRI scanner. In the heating measurements, we determined the optimum particle concentration in the aqueous solution and field intensity to satisfy the target temperature of 42oC for magnetic hyperthermia. We also estimated the SAR of the particles which is an important factor for the practical applications of nanoparticles to hyperthermia. The particles satisfied the criteria of the SAR value for magnetic hyperthermia applications. In the MR measurements, we observed that the particles showed the strong T2 relaxation effect. The T2 relaxivity of the particles was very large, which revealed that these particles can be used as high efficiency T2 contrast agents. We also synthesized the gadolinium-doped lanthanum strontium manganite nanoparticles to see if these particles can be applied to self-controlled hyperthermia. The Curie temperature of these particles was as low as 310 K. In the heating measurements of these particles, we could observe that these particles can be used as heat generators for self-controlled magnetic hyperthermia.
Thesis Advisor: Prof. Ilsu Rhee