A study of uncoated and coated nickel-zinc ferrite nanoparticles for magnetic hyperthermia

Abstract

The paper describes how to arrive at the required characteristics suitable for the study of magnetic hyperthermia in a nanoferrite. The composition selected for the study, Ni0.60Zn0.35Fe2.05O4 was synthesized by sol-gel process with an adequate control on its particle size using a chelating agent, polyethylene glycol (PEG). Nanoparticles with mean particle sizes in the range 3.6–8.2 nm were obtained by annealing the as-prepared powder at different temperatures. Identification of single phase spinel structure, particle size determination and magnetic properties of all the samples were made available with X-ray diffraction, Transmission electron microscopy, and Vibration sample magnetometer. The single domain nature of the nanoparticles was established from the particle size dependence of the coercivity. The superparamagnetic behaviour of two annealed samples having a mean particle sizes 3.6 nm and 4.4 nm was established from the temperature dependence of the field cooling and zero field cooling magnetization curves. The observed higher blocking temperature (below room temperature) for smaller particles was attributed to interactions between the particles in the powder samples. The effect of interparticle interactions on heating efficiency was examined by comparing the specific absorption rate (SAR) of nanoparticles dispersed in water at different concentrations. The higher zeta potential values of citric acid coated nanoparticles were pronouncing their long time stability in water with increased SAR and cell viability as compared to their uncoated counterparts. Interestingly, the results of water based citric acid coated nanoparticles assure that the material would be suitable as magnetic mediator for magnetic hyperthermia application.