Controllable 5-sulfosalicylic acid assisted solvothermal synthesis of monodispersed superparamagnetic Fe_3O_4 nanoclusters with tunable size

摘要

Monodispersed Fe_3O_4 nanoclusters were synthesized in a one-pot solvothermal route with 5-sulfosalicylic acid (SSA) as the functional ligand in a mixed-solvent system of diethylene glycol/ethylene glycol (DEG/EG). Nucleation and aggregation growth model was responsible for the formation of secondary structure of the clusters. In the process, the size of the clusters can be effectively controlled by varying the amounts of SSA and the volume ratio of DEG/EG. The nanoclusters exhibited superparamagnetic properties with high saturation magnetization value of about 68.7 emu g~(-1) at room temperature. The water-soluble small-molecule SSA grafted on the surface of Fe_3O_4 nanocrystals rendered the superparamagnetic clusters dispersible in water, which is crucial for potential applications in biomedical fields.