الوصف: |
Background:It is well known that copper oxide nanoparticles (CuO NPs) are heavily toxic on in vitro systems. In human alveolar epithelial cells, the mechanism of toxicity is mostly related to oxidative insults, coming from intracellularly dissolved copper ions, finally leading to apoptotic or autophagic cell death.Our hypothesis is based on possible early oxidative events coming from specific NP surface reactivity able to undermine the cell integrity and to drive cell to death, independently from lysosomal-enhanced Trojan horse mechanism. Two types of CuO NPs, with different oxidative potential, were selected and tested on A549 cells for 1h and 3h at 10, 25, 50 and 100 mg/mL. Cells were then analyzed for viability and oxidative change of the proteome. Oxidative by-products were localized by immunocytochemistry and cell-NP interactions characterized by confocal and electron microscopy techniques.Results:CuO NPs induced oxidative changes soon after 1 h exposure as revealed by the increase in protein carbonylation and reduced-protein-thiol oxidation. In parallel, cell viability significantly decreased, as shown by MTT assay. Such effects were higher for CuO NPs with more crystalline defects and with higher ROS production than for fully crystalline NPs. At these exposure times, although NPs efficiently interacted with cell surface and were taken up by small endocytic vesicles, no ion dissolution is visible inside endo-lysosomal compartment and no effects were produced by extracellularly dissolved copper ions.Conclusions:A specific NP surface-dependent oxidative cell injury was demonstrated. More detailed studies are required to understand which targets precociously react to CuO NPs, but these results introduce new paradigms for the toxicity of the metal-based NPs, beyond the Trojan horse-related mechanism, and opens-up new opportunities to investigate the interactions and effects at the bio-interface for designing safer as well as more effective CuO-based biocides. |