Superparamagnetic α-Fe₂O₃/Fe₃O₄ Heterogeneous Nanoparticles with Enhanced Biocompatibility

A novel type of magnetic α-Fe₂O₃/Fe₃O₄ heterogeneous nanoparticles was prepared via a facile solution combustion process with ferric nitrate and urea as raw materials, and they were characterized by XRD, SEM, TEM, and VSM techniques. The effects of the calcination temperature, the calcination time, the ratio of ferric nitrate and urea, and the heating rate on the relative content of Fe₃O₄ in the heterogeneous nanoparticles were investigated. The toxicity of α-Fe₂O₃/Fe₃O₄ heterogeneous nanoparticles to human hepatocytes L-02, the blood routine, and the histopathological section observation of mice were explored. The results showed that the ratio of ferric nitrate and urea was a key factor to affect the relative content of Fe₃O₄ in the heterogeneous nanoparticles. The calcination temperature and the calcination time had similar influences, and the corresponding calcination temperature and the calcination time were selected according to their own needs. The CCK8 results initially revealed that α-Fe₂O₃/Fe₃O₄ heterogeneous nanoparticles had no effect on cell viability when the concentration of the heterogeneous nanoparticles was less than 100 ng/mL, which suggested their excellent biocompatibility. At the same time, the tail vein administration concentration of 0.9 mg/kg had good biological safety.