Mass spectrometry-based metabolomics to assess uptake of silver nanoparticles by Arabidopsis thaliana

Abstract

Silver nanoparticles (AgNPs) are one of the most commonly utilized engineered nanomaterials in consumer products due to their antimicrobial properties. AgNPs can be introduced into the environment when products containing AgNPs are disposed of in landfills, or leach out from products during washing, eventually reaching wastewater treatment plants. Hence, the usage of reclaimed water can lead to the unintentional exposure of different biological organisms to AgNPs. In addition, biosolids from wastewater treatment plants may contain AgNPs that can end up in the environment when the biosolids are land-applied to fertilize fields. In this study, the impact of citrate- and polyvinylpyrolidone-coated AgNPs on a model plant, Arabidopsis thaliana, was investigated using hydroponic cultures to quantitatively evaluate plant uptake of AgNPs, and to demonstrate the use of a metabolomics approach in assessing sub-lethal effects of AgNPs on plants. Analysis of AgNPs was performed using inductively coupled plasma mass spectrometry (ICP-MS) to quantify total silver concentrations in plant tissues, and metabolite profiling was achieved using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF/MS). Results show silver translocation from roots of Arabidopsis thaliana to leaves and flowering shoots in all plants treated with AgNPs. Furthermore, untargeted and targeted metabolomics results show alterations in the metabolome after treatment, as well as the accumulation of specific phytosphingosines and N-acylethanolamines in silver treated Arabidopsis thaliana. Correlating the silver concentrations in Arabidopsis thaliana and the changes in metabolite profile may provide insights on the mechanism and interactions between nanomaterials and biological organisms. This study lays the groundwork and provides a proof-of-concept on the utilization of mass spectrometry-based metabolomics as a tool for determining the biochemical effects of nanoparticles at sub-lethal concentrations in Arabidopsis thaliana.