Mixed Solvent-Based Low Temperature Synthesis of Functionalized Cubic FeCo Theranostic Nanoparticles

FeCo alloy nanoparticles were rapidly synthesized by a salt-mediated mixed-polyol process without surfactants at a low reaction temperature (50 °C–100 °C) and its influence on particle size, shape, and composition were investigated. The presence of mixed polyols increase the viscosity of the solution, reducing the migration rate of cations, alter the diameter of FeCo nanoparticles and nucleation rate, and control particle morphology without the use of surfactants. Cubic FeCo nanoparticles were synthesized without surfactants even at a reaction temperature as low as 50 °C. X-ray diffractometry, scanning electron microscopy and transmission electron microscopy showed that as-synthesized FeCo nanoparticles had a body-centered cubic (BCC) crystal structure with a particle size ranging from 25 to 75 nm in effective diameter, respectively. The maximum saturation magnetization of about 207 emu/g and a coercivity of ~100 Oe were achieved at room temperature for samples synthesized at 90 °C. These soft magnetic FeCo nanoparticles can be applied in preparing conjugated nanoparticles for both diagnostic and therapeutic biomedical applications.