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

ABSTRACT 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.