High intrinsic loss power of multicore magnetic nanoparticles with blood-pooling property for hyperthermia

Magnetic hyperthermia is a promising application of magnetic nanoparticles (MNPs) in cancer therapy. It is important to consider and optimize the parameters that affect heat dissipation, such as particle diameters, structures, and surface coatings. In this study, we measured the magnetic properties of two superparamagnetic nanoparticles under DC and AC magnetic fields. Resovist is approved to be used as a magnetic resonance imaging contrast agent. CMEADM-033-02, with the blood-pooling property and biocompatibility, exhibits high magnetization. The blood-pooling property makes it easier for MNPs to accumulate in tumors and tissue. While preparing samples, we aligned the easy axis of the samples using a DC magnetic field to enhance heat dissipation. We discussed the magnetic property in terms of magnetic relaxation associated with anisotropy energy. We observed that the peak frequency of Néel relaxation was considerably shifted owing to effectively changed anisotropy by the alignment of the easy axis. However, the change in the peak frequency of Néel relaxation could not be directly confirmed. Furthermore, we calculated the intrinsic loss power (ILP) and specific loss power (SLP) for heat dissipation from the areas of AC magnetization curves and estimated the SLP at 1 MHz to compare with the high heating characteristic of ILP that has been reported in a conventional study. We achieved equivalent ILP for heat dissipation as that reported in the study by aligning the easy axis of the MNPs with the blood-pooling property under a therapeutic condition.