Strong magnetic field effects on solid-liquid and particle-particle interactions during the processing of a conducting liquid containing non-conducting particles

Biocompatibility of magnetic Fe₃O₄ nanoparticles and their cytotoxic effect on MCF-7 cells

Background

The objective of this study was to evaluate the synthesis and biocompatibility of Fe₃O₄ nanoparticles and investigate their therapeutic effects when combined with magnetic fluid hyperthermia on cultured MCF-7 cancer cells.

Methods

Magnetic Fe₃O₄ nanoparticles were prepared using a coprecipitation method. The appearance, structure, phase composition, functional groups, surface charge, magnetic susceptibility, and release in vitro were characterized by transmission electron microscopy, x-ray diffraction, scanning electron microscopy-energy dispersive x-ray spectroscopy, and a vibrating sample magnetometer. Blood toxicity, in vitro toxicity, and genotoxicity were investigated. Therapeutic effects were evaluated by MTT [3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide] and flow cytometry assays.

Results

Transmission electron microscopy revealed that the shapes of the Fe₃O₄ nanoparticles were approximately spherical, with diameters of about 26.1 ± 5.2 nm. Only the spinel phase was indicated in a comparison of the x-ray diffraction data with Joint Corporation of Powder Diffraction Standards (JCPDS) X-ray powder diffraction files. The O-to-Fe ratio of the Fe₃O₄ was determined by scanning electron microscopy-energy dispersive x-ray spectroscopy elemental analysis, and approximated pure Fe₃O₄. The vibrating sample magnetometer hysteresis loop suggested that the Fe₃O₄ nanoparticles were superparamagnetic at room temperature. MTT experiments showed that the toxicity of the material in mouse fibroblast (L-929) cell lines was between Grade 0 to Grade 1, and that the material lacked hemolysis activity. The acute toxicity (LD₅₀) was 8.39 g/kg. Micronucleus testing showed no genotoxic effects. Pathomorphology and blood biochemistry testing demonstrated that the Fe₃O₄ nanoparticles had no effect on the main organs and blood biochemistry in a rabbit model. MTT and flow cytometry assays revealed that Fe₃O₄ nano magnetofluid thermotherapy inhibited MCF-7 cell proliferation, and its inhibitory effect was dose-dependent according to the Fe₃O₄ nano magnetofluid concentration.

Conclusion

The Fe₃O₄ nanoparticles prepared in this study have good biocompatibility and are suitable for further application in tumor hyperthermia.