title: More than the ions: the effects of silver nanoparticles on Lolium multiflorum.
abstract: Silver nanoparticles (AgNPs) are increasingly used as antimicrobial additives in consumer products and may have adverse impacts on organisms when they inadvertently enter ecosystems. This study investigated the uptake and toxicity of AgNPs to the common grass, Lolium multiflorum. We found that root and shoot Ag content increased with increasing AgNP exposures. AgNPs inhibited seedling growth. While exposed to 40 mg L(-1) GA-coated AgNPs, seedlings failed to develop root hairs, had highly vacuolated and collapsed cortical cells and broken epidermis and rootcap. In contrast, seedlings exposed to identical concentrations of AgNO(3) or supernatants of ultracentrifuged AgNP solutions showed no such abnormalities. AgNP toxicity was influenced by total NP surface area with smaller AgNPs (6 nm) more strongly affecting growth than did similar concentrations of larger (25 nm) NPs for a given mass. Cysteine (which binds Ag(+)) mitigated the effects of AgNO(3) but did not reduce the toxicity of AgNP treatments. X-ray spectro-microscopy documented silver speciation within exposed roots and suggested that silver is oxidized within plant tissues. Collectively, this study suggests that growth inhibition and cell damage can be directly attributed either to the nanoparticles themselves or to the ability of AgNPs to deliver dissolved Ag to critical biotic receptors.
authors.affiliation: Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, People's Republic of China.
authors.forename: Liyan
authors.initials: L
authors.lastname: Yin
authors.forename: Yingwen
authors.initials: Y
authors.lastname: Cheng
authors.forename: Benjamin
authors.initials: B
authors.lastname: Espinasse
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Colman
authors.forename: Melanie
authors.initials: M
authors.lastname: Auffan
authors.forename: Mark
authors.initials: M
authors.lastname: Wiesner
authors.forename: Jerome
authors.initials: J
authors.lastname: Rose
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Emily S
authors.initials: ES
authors.lastname: Bernhardt
mesh_terms: D004305:Dose-Response Relationship, Drug; D008129:Lolium / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D012834:Silver / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity
chemical_list: D012989:Soil Pollutants; D012834:Silver