Toxicological assessment of multi-walled carbon nanotubes on A549 human lung epithelial cells

[Display omitted] •MWCNTs uptake is efficient and causes mechanical damages in cell compartments.•Lysosomal dysfunctions due to MWCNTs are inversely related to cell viability.•Genotoxicity of pristine MWCNTs could be due to aneugenic effects.•ROS overproduction is neutralized by chelating compound, highlighting the iron role.•Redox imbalance is probably due to intralysosomal low-molecular-mass iron. An in vitro model resembling the respiratory epithelium was used to investigate the biological response to laboratory-made pristine and functionalised multi-walled carbon nanotubes (pMWCNT and MWCNT-COOH). Cell uptake was analysed by MWCNT-COOH, FITC labelled and the effect of internalisation was evaluated on the endocytic apparatus, mitochondrial compartment and DNA integrity. In the dose range 12.5–100μgml−1, cytotoxicity and ROS generation were assayed, evaluating the role of iron (the catalyst used in MWCNTs synthesis). We observed a correlation between MWCNTs uptake and lysosomal dysfunction and an inverse relationship between these two parameters and cell viability (P