title: Silver nanoparticles induced accumulation of reactive oxygen species and alteration of antioxidant systems in the aquatic plant Spirodela polyrhiza.
abstract: 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. The authors used Spirodela polyrhiza to investigate whether AgNPs can induce oxidative stress in higher plants. Results showed that there was a dose-dependent increase in levels of reactive oxygen species, superoxide dismutase and peroxidase activity, and the antioxidant glutathione content in 6-nm AgNP treatments. Catalase activity and malondialdehyde content in 6-nm AgNP treatments was significantly higher than the control at silver concentrations of 5 mg L(-1) . Superoxide dismutase and catalase activity and antioxidant glutathione and malondialdehyde content were not significantly different at 10 mg L(-1) of AgNPs (6 nm and 20 nm). Treatment with 20 µg L(-1) Ag(+) (the amount almost equal to 10 mg L(-1) AgNPs released) did not change the reactive oxygen species level or antioxidant enzymes activity. Micron-sized Ag particles had no effect on S. polyrhiza. Transmission electron microscopy showed that, compared with the control, chloroplasts in S. polyrhiza treated with 6-nm and 20-nm AgNPs accumulated starch grains and had reduced intergranal thylakoids. These results clearly indicate that AgNPs are able to cause oxidative stress and affect the chloroplast structure and function of S. polyrhiza, and this effect was not caused by Ag(+) released from particles.
authors.affiliation: Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China; Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Hainan University, HaiKou, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Hong-Sheng
authors.initials: HS
authors.lastname: Jiang
authors.forename: Xiao-Ni
authors.initials: XN
authors.lastname: Qiu
authors.forename: Gen-Bao
authors.initials: GB
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Li-Yan
authors.initials: LY
authors.lastname: Yin
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D029064:Araceae / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D005978:Glutathione / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D053768:Metal Nanoparticles / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects; D010316:Particle Size; D010940:Plant Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012834:Silver / Q000737:chemistry* / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D003470:Culture Media; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D012834:Silver; D008315:Malondialdehyde; D005978:Glutathione
keywords: Aquatic plant; Nanotoxicology; Oxidative stress; Silver nanoparticles; Ultrastructure