Evaluating PVP coated iron oxide particles for localized magnetic hyperthermia and MRI imaging

Ferrofluids based on magnetic iron oxide nanoparticles (IONPs) have been widely studied as multipurpose agents in various medical applications including magnetic hyperthermia, targeted drug delivery and magnetic resonance imaging (MRI). To increase their stability and compatibility with the living cells and thus improve their suitability for these purposes, the IONPs are often functionalized with different organic or inorganic molecules. In this work we report on the preparation of polyvinilpyrrolidone (PVP) functionalized IONPs through a simple co-precipitation method and investigated their suitability for magnetic hyperthermia and as a MRI contrast agent. Spherical PVP-coated IONPs, with an average particle size of approximate to 15 nm, showed superparamagnetic behavior and high saturation magnetization Ms = 80.7 emug-1, at room temperature. The specific absorption rate (SAR), a measure of the heating ability, ranged from 17 W/g to 721 W/g (evaluated for various combinations of AC magnetic field amplitudes and frequencies), while the intrinsic loss power (ILP) was in the range from 0.53 nHm2 kg-1 to 2.34 nHm2 kg-1. In addition to relatively good heating ability, high T2 relaxivity, r2 = 126 mM-1 s-1 and high r2/r1 ratio demonstrated that the preparation procedure used here can yield nanoparticles suitable for MRI guided localized magnetic hyperthermia.