This paper reports first on the very promising self-heating and temperature rising characteristics of solid-state NiFe $_2$ O $_4$ nanoparticles for hyperthermia applications. NiFe $_2$ O $_4$ nanoparticles were prepared by using both the “high temperature thermal decomposition method (HTTD)” and the “newly modified sol-gel” methods. The magnetic properties and cell-cytotoxic properties of the synthesized NiFe $_2$ O $_4$ nanoparticles were investigated to consider these nanoparticles for in vivo hyperthermia applications. The saturation magnetic moments measured by a high sensitive SQUID were between 43.0 and 47.6 emu/g. The cell survival rates of NiFe $_2$ O $_4$ and chitosan coated NiFe $_2$ O $_4$ , which were determined by MTT assay, around 85 % and 98.8 %, respectively. The maximum self-heating temperature induced by our specially designed RF-MRI modified L-C circuit was 47.3 $^circ$ C and the frequency and magnetic field product, $H_0f$ was 1.07 $times$ 10 $^9$ Am $^-1$ s $^-1$ .

S.W. Lee

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