Toxicology assessment of manganese oxide nanomaterials with enhanced electrochemical properties using human in vitro models representing different exposure routes

In the present study, a comparative human toxicity assessment between newly developed Mn3O4 nanoparticles with enhanced electrochemical properties (GNA35) and their precursor material (Mn3O4) was performed, employing different in vitro cellular models representing alveolar, oral and dermal exposure routes, namely the human alveolar carcinoma epithelial cell line (A549), the human colorectal adenocarcinoma cell line (HT29), and the reconstructed 3D human epidermal model EpiDerm (RhE). The obtained results showed that Mn3O4 and GNA35 harbour similar morphological characteristics, while differences were observed in relation to their thermal stability and electrochemical properties. In regard to their toxicological properties, both nanomaterials induced oxidative stress in the A549 and HT29 cell lines that have demonstrated that manganese oxide nanoparticles reduce the cell viability in A549 cells while they do not produce any negative effect on that of HT29 cells. On the other hand, it was observed that Mn3O4 and GNA35 induce oxidative stress in both cell lines. Finally, it was noticed that none of the nanoparticles caused a reduction of the viability on the skin tissue so that they could not be classified as irritants. Our findings demonstrate that the evaluation of the toxicity of nanoparticles using different models is a critical aspect to increase the knowledge on their potential impact on human health.