Investigation of Cr3+ doped Zn-Co nanoferrites as potential candidate for self-regulated magnetic hyperthermia applications

Abstract

Controlling the Curie temperature (TC) in the range from 42 °C–46 °C in magnetic hyperthermia (MH) therapy is an essential research topic because overheating can cause irreversible damage to healthy tissue. When TC is in the above temperature range, the magnetic nanoparticles reach a paramagnetic state, effectively turning off the MH treatment. In this work, we synthesized Zn-Co nanoparticles of representative composition Zn0.54Co0.46CrxFe2-xO4, where the Fe3+ cations are carefully replaced by Cr3+ ions, which allow a precise tuning of TC and hence the self-regulation of MH. The x-ray diffraction analysis of the prepared nanoparticles confirms the formation of a single-phase cubic spinel structure. The average crystallite of the nanoparticles increases with Cr3+ doping, while the Tc and saturation magnetization decrease considerably from 78 °C (x = 0.1) to 27 °C (x = 0.6) and 46.6 emu g−1 (x = 0.1) to 15.3 emu g−1 (x = 0.6), respectively. Besides MH potential of the investigated samples as revealed from specific absorption rate (SAR) assays and the maximum temperature reach (Tmax), vary from 7 W g−1 and 37.3 °C, for x = 0.6, to 38 W g−1 and 62.9 °C, for x = 0.1, we found that the composition Zn0.54Co0.46Cr0.4Fe1.6O4 is more promising with SAR of 22 W g−1 and Tmax = 42.3 °C, which is precisely lies in the safe temperature range to automatically activate the self-regulation during the magnetic hyperthermia treatment. The results reveal an excellent combination between size distribution and Cr3+ content in Zn-Co-based ferrite, which has a great potential for self-regulated magnetic hyperthermia applications.