Co-exposure of silver nanoparticles and chiral herbicide imazethapyr to Arabidopsis thaliana: Enantioselective effects

In this study, we investigated the possible combined exposure effects of silver nanoparticles (Ag-NPs) and chiral herbicide imazethapyr (IM) on Arabidopsis thaliana. Herein, we show that co-exposure of AgNPs and chiral herbicide IM to A. thaliana can amplify the enantioselective ecotoxicity. It was found that after co-exposure of the herbicidally active 0.2 mu M (R)-IM and 100 mu M Ag-NPs, the silver concentration in roots was 1.40-fold higher than the co-exposure of Ag-NPs and (S)-enantiomer, as well as occurring in shoots that Ag-NPs combined with (R)-IM increased the Ag+ concentration 77.78% than that with (S)-IM, suggesting an (R)-enantiomer preferential silver uptake. Increase of Ag+ release under co-exposure of Ag-NPs and (R)-enantiomer was also observed. Our experiments indicated that under co-exposure of AgNPs and (R)-enantiomers, more accumulated amino acids can form more adducts with Ag+, resulting in more Ag+ release from Ag-NPs and higher ecotoxicity. (C) 2015 Elsevier Ltd. All rights reserved.