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Fe 3 O 4 nanoparticles coated with chito-oligosaccharides (COS) were prepared in situ by a simple co-precipitation method through a mixing of iron ions (Fe 3+ and Fe 2+ ) and COS aqueous solutions followed by precipitation with ammonia. The impact of COS with different degree of polymerization (DP 10, 24 and 45) and degree of Nacetylation (DA) ∼ 24 and 50 % (exhibiting high solubility) on the synthesis and physical properties of the coated magnetic nanoparticles was evaluated. Several advantages were found when the magnetic nanoparticles were prepared in the presence of the studied COSs, such as: preparation of functionalized magnetic nanoparticles with narrower size distributions and, consequently, higher saturation magnetization (an increase of up to 22%); and an expressive increasing in the concentration of COS-coated magnetic nanoparticles (up to twice) in the cell viability test in comparison with pure Fe 3 O 4 nanoparticles. Furthermore, among the analyzed samples, the magnetic nanoparticles coated by COS with DA ∼ 50 % present a higher cytocompatibility. Our results allow envisioning various biomedical applications, valorizing the use of coated-magnetic nanoparticles for magneticfield assisted drug delivery, enzyme or cell immobilization, or as a marker for specific cell tracking, among others.

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Cancer is one of the most common diseases nowadays and derives from the uncontrollable growth of a single cell. Magnetic nanoparticles (NpMag) offer various possibilities for use in the biomedical area, including drug delivery mediated by magnetic fields. In the current study, we evaluated the in vitro effects of iron-oxide magnetic nanoparticles conjugated with the antitumor drug doxorubicin (Dox) on human breast cancer cells. Our results revealed that magnetic nanoparticles with Dox (NpMag+Dox) induce cellular redox imbalance in MCF-7 cells. We also demonstrate that iron-oxide nanoparticles functionalized with Dox induce oxidative stress evidenced by DNA damage, lipid peroxidation, cell membrane disruption, and loss of mitochondria potential. As a result, NpMag+Dox drives MCF-7 cells to stop the cell cycle and decrease cell migration. The association of NpMg+Dox induced a better delivery of Dox to MCF cells, mainly in the presence of a magnetic field, increasing the death of MCF cells which might reduce the toxicity for healthy cells providing a better efficacy for the treatment. Thus, iron-oxide nanoparticles and doxorubicin conjugated may be candidate for anticancer therapy.

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