Iron-Cobalt Ferrite Nanoparticles—Biocompatibility and Distribution After Intravenous Administration to Rat

The biocompatibility of iron-cobalt ferrite magnetic nanoparticles (MNP) in vitro and in vivo and their distribution under an external magnetic field after intravenous administration to tumor-bearing rats were studied. In vitro rat mesenchymal stem cells and human larynx carcinoma HEp-2 cells accumulated the magnetic material intracellularly. The proliferation of HEp-2 cells was inhibited moderately by the MNP containing ca. 1.5% Co (either uncoated or polysiloxane-coated) and effectively-by the MNP containing ca. 25% Co. In vivo the most MNP-accumulating organs were the spleen, the kidneys, and the liver. No accumulation of the MNP was observed in the brain. It was found that the differences in the MNP distribution caused by topical application of a magnet were more pronounced at 24 h post injection than at 0.5-3.0 h-while the expected plasma life of the MNP doesn´t exceed 10 min. E.g., application of the magnet caused a 2.4-fold MNP-attributed increase in iron concentration in M-1 sarcoma model at 24 h post injection. Similarities were found in lymph tissue tropism between our particles that readily agglutinate in plasma-containing media and nonagglutinating, long-circulating MNP reported by other authors.