Characterization of Zinc-Doped Cobalt Ferrite Nanoparticles for Application as Heat Generators in Magnetic Hyperthermia and MRI Contrast Agents

摘要

Co0.6Zn0.4Fe2O4 nanoparticles were synthesized using a one-step hydrothermal technique. Then, the particles were encapsulated with a silica shell to obtain a highly stable and nontoxic aqueous suspension. The average diameter of the particles was 90 nm, with a core-shell structure in which multiple particles constitute the core. We characterized the particles to check whether they could be used as both heat generators in magnetic hyperthermia and enhancers of the relaxation process in magnetic resonance imaging (MRI). The particles' heat-generating capability was confirmed by measuring the saturation temperature of a dispersion of particles in an alternating magnetic field with an intensity of 4.4 kA/m at 260 kHz. The saturation temperature of a dispersion with a particle concentration as low as 6 mg/mL was larger than 42 degrees C, which is the therapeutic temperature of magnetic hyperthermia. An enhancement of the hydrogen proton's relaxation process in the aqueous solution of particles was observed using a 4.7 T MRI scanner. The T-2 relaxivity was found to be 126.86 mM(-1)s(-1), much higher than that reported for corresponding particles. From these measurements, we can conclude that our particles are suitable for application to both magnetic hyperthermia and MRI.