title: Comparative toxicity of silver nanoparticles on oxidative stress and DNA damage in the nematode, Caenorhabditis elegans.
abstract: This study examined the effects of polyvinylpyrrolidone (PVP) surface coating and size on the organismal and molecular toxicity of silver nanoparticles (AgNPs) on the nematode, Caenorhabditis elegans. The toxicity of bare AgNPs and 8 and 38 nm PVP-coated AgNPs (PVP8-AgNPs, PVP38-AgNPs) were compared. The toxicity of AgNO3 was also tested because ion dissolution and particle-specific effects are often important characteristics determining Ag nanotoxicity. Comparative toxicity across AgNO3 and the three different types of AgNPs was first evaluated using a C. elegans mortality test by a direct comparison of the LC50 values. Subsequently, mutant screening followed by oxidative stress, mitochondrial toxicity and DNA damage assays were carried out at equitoxic (LC10 and LC50) concentrations to further assess the toxicity mechanism of AgNO3 and AgNPs. AgNO3 and bare AgNPs had similar toxicities, whereas PVP coating reduced the toxicity of the AgNPs significantly. Of the PVP-AgNPs, the smaller NPs were more toxic. Different groups of mutants responded differently to AgNO3 and AgNPs, which indicates that their toxicity mechanism might be different. AgNO3 and bare AgNPs induced mitochondrial membrane damage. None of the silver materials tested caused detectable polymerase-inhibiting DNA lesions in either the nucleus or mitochondria as measured by a quantitative PCR assay, but AgNO3, bare AgNPs and PVP8-AgNPs induced oxidative DNA damage. These results show that coatings on the AgNPs surface and the particle size make a clear contribution to the toxicity of the AgNPs, and oxidative stress-related mitochondrial and DNA damage appear to be potential mechanisms of toxicity.
authors.affiliation: School of Environmental Engineering, University of Seoul, Seoul 130-743, Republic of Korea; Graduate School of Energy and Environmental system Engineering, University of Seoul, Seoul 130-743, Republic of Korea.
authors.forename: Jeong-Min
authors.initials: JM
authors.lastname: Ahn
authors.affiliation: School of Environmental Engineering, University of Seoul, Seoul 130-743, Republic of Korea; Graduate School of Energy and Environmental system Engineering, University of Seoul, Seoul 130-743, Republic of Korea.
authors.forename: Hyun-Jeong
authors.initials: HJ
authors.lastname: Eom
authors.affiliation: Nicholas School of the Environment and Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC, USA.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Yang
authors.affiliation: Nicholas School of the Environment and Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC, USA.
authors.forename: Joel N
authors.initials: JN
authors.lastname: Meyer
authors.affiliation: School of Environmental Engineering, University of Seoul, Seoul 130-743, Republic of Korea; Graduate School of Energy and Environmental system Engineering, University of Seoul, Seoul 130-743, Republic of Korea. Electronic address: jinhchoi@uos.ac.kr.
authors.forename: Jinhee
authors.initials: J
authors.lastname: Choi
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects*; D004272:DNA, Mitochondrial / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D010316:Particle Size; D011205:Povidone / Q000737:chemistry / Q000633:toxicity*; D012834:Silver / Q000737:chemistry / Q000633:toxicity*; D012835:Silver Nitrate / Q000737:chemistry / Q000633:toxicity*
chemical_list: D004272:DNA, Mitochondrial; D012834:Silver; D012835:Silver Nitrate; D011205:Povidone
keywords: Caenorhabditis elegans; Comparative toxicity; Mitochondrial toxicity; Oxidative DNA damage; Silver nanoparticles