Biological mechanism of cell oxidative stress and death during short-term exposure to nano CuO

Abstract

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 1 h and 3 h at 10, 25, 50 and 100 µg/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. The results show that 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 was visible inside the lysosomal compartment and no effects were produced by extracellularly dissolved copper ions. In conclusion, a specific NP surface-dependent oxidative cell injury was demonstrated. More detailed studies are required to understand which targets precociously react with CuO NPs, but these results introduce new paradigms for the toxicity of the metal-based NPs, beyond the Lysosomal-Enhanced Trojan horse-related mechanism, and open-up new opportunities to investigate the interactions and effects at the bio-interface for designing safer as well as more effective CuO-based biocides.

A network toxicology approach for mechanistic modelling of nanomaterial hazard and adverse outcomes

“…This is in line with the other findings that report a toxicity mechanism mainly based on oxidative insults [43]. Similar results were also observed in the A549 cell line, revealing an acute genotoxicity of nano-sized CuO, which is well captured by our framework [43][44][45].…”

“…Interestingly, the predicted MIEs included alteration of the oxidative status in all the test systems, and alteration of ion pumps and receptors in both lung and BEAS-2B. This is in line with the other findings that report a toxicity mechanism mainly based on oxidative insults [43]. Similar results were also observed in the A549 cell line, revealing an acute genotoxicity of nano-sized CuO, which is well captured by our framework [43][44][45].…”

Acute exposure to copper oxide nanoparticles impairs testicular function and sperm quality in adult male albino rats

“…Recent studies have demonstrated that testes are susceptible to oxidative stress because of exposure to copper oxide nanoparticles. Reactive oxygen species (ROS) generation and the body's capacity to detoxify them are out of balance, which causes oxidative stress and cellular damage (Moschini et al, 2023).Even though metal ion dissolution may ultimately contribute to the cytotoxicity caused by CuO NPs, most research tends to blame the harmful impact on the particle's reactivity. Numerous articles have noted that less than half of the overall impact of CuO NPs cytotoxicity is attributable to the extracellularly dispersed copper ions confirming that oxidative stress is a significant factor in cell death (Hanagata et al, 2011;(Wang et al, 2012).…”

“…Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report). Pure and Applied Chemistry, 87 (9)(10)…”

Cellular journey of nanomaterials: Theories, trafficking, and kinetics

“…Cu 2 O and CuO NPs would release ions in the endosomal compartment as they were soluble in the culture medium. [82,83] In the following trafficking, NMs in the endosome were released into the extracellular environment through endosome recycling, or accumulated in multivesicular endosomes followed by transport to lysosomes. [30,84] The latter trafficking is always along with progressive acidification and degradation.…”