Prolonged heating of Fe3O4–Au hybrid nanoparticles in a radiofrequency solenoid coil

Abstract

We report the hyperthermia properties of Fe3O4–Au hybrid nanoparticles (HNPs) under a biocompatible alternating magnetic field (AMF) of 1.5 kAm−1 and 200kHz. The HNPs were prepared by growing Au nanoparticles (AuNPs) with an average diameter of 3nm on the surface of Fe3O4 magnetic nanoparticles (MNPs) with an average diameter of 10nm. The structural properties were determined by transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD). Under the AMF, the initial heating rate of the HNPs solution was lower than that of the MNPs solution because HNPs have a reduced saturation magnetization (Ms) value compared to MNPs. The continued AMF application increased the temperature of the HNPs solution steadily while the MNPs solution reached a thermal equilibrium. The heating effect of AuNPs conjugated to diamagnetic and non-conductive SiO2 nanoparticles (SiO2-AuNPs) was demonstrated under the same AMF condition, which suggests that the prolonged heating of HNPs can be attributed to the additional heating of AuNPs in the radiofrequency (RF) solenoid coil.