Cover Feature: Magnetic Relaxation and Modification of Thiol Groups on Co‐Mg Ferrite Nanoparticles for Theranostics (ChemNanoMat 10/2022)

Magnetic nanoparticles (MNPs) have been actively researched for biomedical applications. This work reports the magnetic and thermal properties of various types of MNPs and confirms a significant hyperthermia effect of Mn-Zn ferrite nanoparticles in human breast cancer cells. Doping with Co ions with larger anisotropy is a possible approach to obtain higher magnetization. However, Co-ferrite particles exhibit hysteresis in their magnetization curves, hindering the maintenance of the superparamagnetic behavior. In contrast, Mg-ferrite micro-order clusters have remarkable heat generation properties for hyperthermia treatment in external magnetic fields. Thus, new properties can be expected from the synergistic effect of Co and Mg ions. Co1-xMgxFe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) nanoparticles embedded in amorphous SiO2 with particle sizes of approximately 4.5 nm were prepared using an original wet chemical method. Spin-echo magnetic resonance imaging measurements were performed for Co1-xMgxFe2O4 nanoparticles using a 0.3-T MRI system. The particles exhibited a significant T2 shortening effect compared with that of agarose, depending on the composition. All particles exhibited effective relaxivity, R2, and a significant contrast was observed in the phantom image. More information can be found in the Research Article by Yuko Ichiyanagi et al.