Coating-dependent induction of cytotoxicity and genotoxicity of iron oxide nanoparticles

Abstract

Surface coatings of nanoparticles (NPs) are known to influence advantageous features of NPs as well as potential toxicity. Iron oxide (Fe₃O₄) NPs are applied for both medical diagnostics and targeted drug delivery. We investigated the potential cytotoxicity and genotoxicity of uncoated iron oxide (U-Fe₃O₄) NPs in comparison with oleate-coated iron oxide (OC-Fe₃O₄) NPs. Testing was performed in vitro in human lymphoblastoid TK6 cells and in primary human blood cells. For cytotoxicity testing, relative growth activity, trypan blue exclusion, ³H-thymidine incorporation and cytokinesis-block proliferation index were assessed. Genotoxicity was evaluated by the alkaline comet assay for detection of strand breaks and oxidized purines. Particle characterization was performed in the culture medium. Cellular uptake, morphology and pathology were evaluated by electron microscopy. U-Fe₃O₄ NPs were found not to be cytotoxic (considering interference of NPs with proliferation test) or genotoxic under our experimental conditions. In contrast, OC-Fe₃O₄ NPs were cytotoxic in a dose-dependent manner, and also induced DNA damage, indicating genotoxic potential. Intrinsic properties of sodium oleate were excluded as a cause of the toxic effect. Electron microscopy data were consistent with the cytotoxicity results. Coating clearly changed the behaviour and cellular uptake of the NPs, inducing pathological morphological changes in the cells.

• Coating
• cytotoxicity
• DNA damage
• genotoxicity
• human lymphoblastoid TK6 cells
• human peripheral lymphocytes
• iron oxide
• nanoparticles

Acknowledgements

The authors would also like to thank D. Cristofori and V. Trevisan (Department of Molecular Sciences and Nanosystems; University Ca' Foscari Venice, Italy), F. Spizzo (Department of Physics, University of Ferrara, Italy), H. Nagyova, E. Mrvikova and K. Gavalova (Slovak Medical University, Bratislava, Slovakia) and F. Bjørklid (NILU, Kjeller, Norway) for their technical support during characterization of the nanomaterials and TEM images. We also are grateful for brilliant assistance with preparation of sections for electron microscopy analysis by Jorunn Knutsen and Bjørg Riber, TEM expertise offered by B. Hakim and access to TEM facilities at Department of Anatomy, University of Oslo, Norway.

Declaration of interest

The authors declare that there is no conflict of interest. The work was supported by EC FP7 NanoTEST [Health-2007-1.3-4], Contract no: 201335, EC FP7 QualityNano [INFRA-2010-1.131], Contract No: 214547-2, EC FP7 NANoREG, [NMP.2012.1.3-3] contract no: 310584, by the ITMS project no. 2424012033, Operational research and development program financed from the European Regional Development Fund and by NILU internal projects 106179 and 106170.