John Wiley & Sons, Ltd.

Silver nanoparticles induced accumulation of reactive oxygen species and alteration of antioxidant systems in the aquatic plant Spirodela polyrhiza

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Silver nanoparticles (AgNPs) are widely used commercially because of their antibacterial properties. Oxidative stress is known to be involved in the toxicity of AgNPs to bacteria, animals and algae. Here we used Spirodela polyrhiza to investigate whether AgNPs can induce oxidative stress in higher plants. Results showed that there was a dose dependent increase of reactive oxygen species (ROS) levels, superoxide dismutase (SOD) and peroxidase (POD) activity and the antioxidant glutathione (GSH) content in 6 nm AgNPs treatments. Catalase (CAT) activity and malondialdehyde (MDA) content in 6 nm AgNPs treatments was significantly higher than the control at silver concentrations of 5 mg L−1. SOD, CAT activity and GSH, MDA content were not significantly different at 10 mg L−1 of AgNPs (6 and 20 nm) treatment. 20 µg L−1 Ag+ (the amount almost equals to 10 mg L−1 AgNPs released) has not changed ROS level and antioxidant enzymes activity. Micron‐sized Ag particles had no effect on S. polyrhiza. Transmission electron microscopy showed that compared to the control, chloroplasts in 6 nm and 20 nm AgNPs treated S. polyrhiza accumulated starch grains and had reduced intergranal thylakoids. These results clearly indicate that AgNPs are able to cause oxidative stress, affect the chloroplast structure and function of S. polyrhiza, and this effect was not caused by Ag+ released from particles. Environ Toxicol Chem © 2014 SETAC

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