Toxicity of iron-based nanoparticles to Nannochloropsis oculata: effects of Fe2O3-NPs on oxidative stress and fatty acid composition

چکیده مقاله

The growing application of nanotechnology has led to the release of nanoparticles in aquatic ecosystems. Thus, investigating the effect of nanoparticles on microalgae, as the primary producers of the food chain, is an important issue. The present study was conducted to examine the toxicity mechanisms of α- Fe₂O₃ nanoparticles (Fe₂O₃-NPs) dominated by oxidative stress in Nannochloropsis oculata. The accumulation of Fe₂O₃-NPs on the cell surface of N. oculata and in f2 medium was observed in SEM images and DLS analysis, respectively. EDX graph and TEM images also showed the presence of NPs in N. oculata. There was an increase of H₂O₂ and MDA content and growth inhibition was also elevated in N. oculata exposed to Fe₂O₃-NPs. Further, Fe₂O₃-NPs application caused a noticeable enhancement of non-enzymatic antioxidants (carotenoids, phenolic compounds and PUFAs) and APX activity, while the content of SFAs and MUFAs as well as the activity of CAT and PPO were reduced as a result of Fe₂O₃-NPs stress. Overall, the activation of defence mechanisms was not effective in N. oculata and treatment with concentrations of more than 50 mg l⁻¹ Fe₂O₃-NPs could induce oxidative stress in this microalga.