Ion-Doped Iron-Based nanoparticles with enhanced magnetic properties: Synthesis and formation mechanism via coprecipitation

Iron-based magnetic nanoparticles have gained significant attention in biomedicine. However, the magnetic properties of iron-based nanoparticles prepared through coprecipitation methods often do not meet application requirements. This study aims to enhance the performance of iron-based magnetic nanoparticles by synthesizing them via the coprecipitation method and doping them with Mn²⁺, Zn²⁺, and Co²⁺ ions in various ratios. Among these, Zn-doped nanoparticles with a 0.6 ratio (ZION-6) exhibits the highest saturation magnetization intensity of 98 emu/g sample and the highest r₂ values of 165.2 mM⁻¹·s⁻¹, making them an effective T₂ MRI contrast agent. Our investigation into the coprecipitation process revealed a formation mechanism for ion-doped magnetic iron-based nanoparticles. This mechanism involves the formation of an intermediate phase, α-FeOOH, followed by phase transformation, ion doping, and the aggregation of small particles to yield the final magnetic nanoparticles. This research could pave the way for developing magnetic nanoparticles with improved properties for biomedical applications.