Experimantal and Theoretcal Study of Magnetic Hyperthermia

Localized magnetic particle hyperthermia heating treatment using ferromagnetic and superparamagnetic nanoparticles continue to be an active area of cancer research. Magnetic hyperthermia is a promising therapeutic method for treatment of cancer. It's based on the intratumoral deposition of biocompatible magnetic nanoparticles followed by exposure to a high-frequency electromagnetic field. The dissipation of energy connected especially with magnetic hysteresis losses, Neel and Brown relaxations results in a local heating of the active particles and consequently leads to the destruction of the cancer cells. Magnetic nanoparticle materials used has to have high specific power loss and a suitable temperature dependence of power loss allowed by an adjustment of the Curie temperature to about 315 K (43 °C). Overheating is ruled out due to a decrease of the magnetic hysteresis losses in the vicinity of the Curie temperature. One way to solve this task is the use of magnetic nanoparticles with the magnetic properties suitably modified by compositional variations. This dissertation, reports on localized magnetic hyperthermia studies using newly fabricated, as-synthesized, self-heating magnetic nanoparticles. Exposed to an alternating magnetic field, these nanoparticles act as localized heat sources at certain target regions inside the human body. Superparamagnetic nanoparticles provide attractive biotechnical and physiological advantages such as: direct injection through blood vessel due to ease of control of particle size, remote controlling of transport to tumor cells by externally applied magnetic field gradients, and resonant response to a time varying magnetic field resulting in heating up nanoparticles. In this dissertation, a report of the very promising and successful self-heating temperature rising characteristics of MnZn-ferrite, ZnGd-ferrite, GdZnCe-ferrite and ZnNd-ferrite nanoparticles obtained by chemical methods, mainly, co-precipitation process and under different applied magnetic fields and frequencies to confirm the effectiveness as hyperthermia agents. Magnetic and structural properties of these nanoparticles were analyzed in order to study the physical nature of self-heating characteristics and to investigate the effectiveness as hyperthermia agents in biomedicine. All four types of nanoparticle systems showed both superparamagnetic and ferromagnetic behaviors depending on particle sizes. Dominant magnetic heating mechanisms were studied and qualitatively identified, and a newly developed mathematical model to calculate the magnetic heating power was derived. The derived model proved to be in good agreement with the experimental results.