A metabolomic study on the responses of daphnia magna exposed to silver nitrate and coated silver nanoparticles

摘要

We examined the short-term toxicity of AgNPs and AgNO3 to Daphnia magna at sublethal levels using H-1 NMR-based metabolomics. Two sizes of polyvinylpyrrolidone-coated AgNPs (10 and 40 nm) were synthesized and characterized and their Ag+ release was studied using centrifugal ultrafiltration and inductively coupled plasma mass spectrometry. Multivariate statistical analysis of the H-1 NMR spectra showed significant changes in the D. magna metabolic profiles following 48 h exposure to both AgNP particle sizes and Ag+ exposure. Most of the metabolic biomarkers for AgNP exposure, including 3-hydroxybutyrate, arginine, lysine and phosphocholine, were identical to those of the Ag+-exposed groups, suggesting that the dominant effects of both AgNPs were due to released Ag+. The observed metabolic changes implied that the released Ag+ induced disturbance in energy metabolism and oxidative stress, a proposed mechanism of AgNP toxicity. Elevated levels of lactate in all AgNP-treated but not in Ag+-treated groups provided evidence for Ag-NP enhanced anaerobic metabolism. These findings show that H-1 NMR-based metabolomics provides a sensitive measure of D. magna response to AgNPs and that further targeted assays are needed to elucidate mechanisms of action of nanoparticle-induced toxicity. (C) 2015 Elsevier Inc. All rights reserved.