Mass-spectrometry based metabolomics has recently emerged as a valuable technique in understanding the ecotoxicity and mode of action of a wide range of xenobiotics in the environment, including engineered nanomaterials (ENMs). However, the applications of metabolomics in elucidating the biochemical pathways affected by xenobiotics have been mostly performed using targeted analysis. In this study, the effects of copper oxide nanoparticles (CuO NPs) on Arabidopsis thaliana, a model plant, was investigated using untargeted metabolite profiling based on two platforms of high-resolution mass spectrometry (MS): (1) liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) and (2) LC Q Exactive™ Hybrid Quadrupole-Orbitrap™-MS (LC-Orbitrap-MS). This approach was performed to identify specific features (mass-to-charge ratios, m/z's) that are significantly changed in a reproducible manner regardless of the MS platform used in metabolomics. In addition, the total copper concentrations taken up in plant tissues were quantified using inductively coupled plasma mass spectrometry (ICP-MS), which provided evidence of translocation of CuO NPs from roots to leaves and flowering shoots. Results from untargeted metabolomics showed that there were 65 plant metabolites that were altered commonly in both LC/MS platforms resulting from CuO NPs exposure of Arabidopsis thaliana. These metabolites belong to the jasmonic acid and glucosinolates pathways, suggesting the stress response induced by CuO NPs in Arabidopsis. This study demonstrated the effectiveness of high-resolution LC/MS in providing insight on the mechanism of nanotoxicity of CuO NPs in plants.
Keywords: Arabidopsis thaliana; CuO NPs; Jasmonates; LC-Q Exactive Orbitrap; LC-QToF; Metabolomics.
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