Today the use of magnetic nanoparticles (MNPs) is widely investigated because of their biocompatibility and nontoxicity. The objective of this study was to synthesis a uniform superparamagnetic Fe3O4, the core–shell structures of chitosan-coated Fe3O4 (cc/Fe3O4) and polyacrylic acid-coated Fe3O4 (pc/Fe3O4) nanoparticles using an in situ co-precipitation process for evaluation of biomedical applications. To structurally characterize the synthesized nanoparticles, morphological and magnetic properties, Fourier transform infrared, X-ray diffraction, transmission electron microscopy, dynamic light scattering and vibrating sample magnetometry studies were employed. Our results showed that Fe3O4, cc/Fe3O4 and pc/Fe3O4 nanoparticles possess an average mean diameter of 10, 15 and 11 nm (dry samples) per Scherrer's equation in a dry state with saturation magnetization (MS) values of 70.64, 38.65 and 23.53 emu/g, respectively. The cytotoxicity of nanoparticles was evaluated by MTT assay using breast cancer (MCF7) and human normal skin (fibroblast) cell lines. Both of the two core–shell structures did not show toxicity on the fibroblast cell line even after 24 and 48 h. The viability rate of the bare Fe3O4 MNPs on the MCF7 cell line was significantly less than two the coated nanoparticles. MTT assays demonstrated that core–shell nanoparticles have less cytotoxicity than bare Fe3O4 MNPs (in 100 μg/ml during 24 h, the viability of bare Fe3O4 MNPs, cc/Fe3O4 and pc/Fe3O4 nanoparticles was 68.01%, 85.91%, and 88.13%, respectively). Moreover, hemolysis assay was performed to measure cytotoxicity of the nanoparticles on red blood cells (RBCs). The cc/Fe3O4 structure at all concentrations had less hemolysis percentage than the pc/Fe3O4 structure. The chitosan-coated Fe3O4 nanoparticle showed the highest biocompatibility.
