Magnetic nanoparticles with low Curie temperature and high heating efficiency for self-regulating temperature hyperthermia

Both low Curie temperature (T-c) and high specific absorption rate (SAR) are desired for magnetic nanoparticles (MNPs) used in magnetic induction hyperthermia (MIH). Here, we report novel MNPs (Zn0.54Co0.46Cr0.6Fe1.4O4) with a T-c of 48.8 degrees C, which meets the requirement for the self-regulating of MIH therapeutic temperature. This low T-c can be attributed to the weak A-B super-exchange interactions caused by the substitution of Zn2+ and Cr3+. The SAR of the MNPs under clinical applied AC magnetic field (16 kA.m(-1), 100 kHz) is up to 6.53 W.g(-1), which is mainly contributed by the relaxation loss. The short relaxation time, caused by the low magnetocrystalline anisotropy, may take responsibility for the occurrence of the relaxation loss. While the low magnetocrystalline anisotropy is related to the low occupation ratio of Co2+ in B sites. The in vitro experiments indicate the self-regulating temperature nature and biocompatibility of the MNPs.