title: Anaerobic toxicity of cationic silver nanoparticles.
abstract: The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag(+) under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged polyvinylpyrrolidone coated AgNPs (PVP-AgNPs) and (3) positively charged branched polyethyleneimine coated AgNPs (BPEI-AgNPs). The AgNPs investigated in this experiment were similar in size (10-15nm), spherical in shape, but varied in surface charge which ranged from highly negative to highly positive. While, at AgNPs concentrations lower than 5mgL(-1), the anaerobic decomposition process was not influenced by the presence of the nanoparticles, there was an observed impact on the diversity of the microbial community. At elevated concentrations (100mgL(-1) as silver), only the cationic BPEI-AgNPs demonstrated toxicity similar in magnitude to that of Ag(+). Both citrate and PVP-AgNPs did not exhibit toxicity at the 100mgL(-1) as measured by biogas evolution. These findings further indicate the varying modes of action for nanoparticle toxicity and represent one of the few studies that evaluate end-of-life management concerns with regards to the increasing use of nanomaterials in our everyday life. These findings also highlight some of the concerns with a one size fits all approach to the evaluation of environmental health and safety concerns associated with the use of nanoparticles.
authors.affiliation: Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH, United States.
authors.forename: Alireza
authors.initials: A
authors.lastname: Gitipour
authors.affiliation: Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH, United States.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Thiel
authors.affiliation: USEPA, Office of Research and Development, Cincinnati, OH, United States.
authors.forename: Kirk G
authors.initials: KG
authors.lastname: Scheckel
authors.affiliation: USEPA, Office of Research and Development, Cincinnati, OH, United States. Electronic address: tolaymat.thabet@epa.gov.
authors.forename: Thabet
authors.initials: T
authors.lastname: Tolaymat
mesh_terms: D000693:Anaerobiosis / Q000187:drug effects*; D001421:Bacteria, Anaerobic; D019343:Citric Acid; D053768:Metal Nanoparticles / Q000633:toxicity*; D010316:Particle Size; D011205:Povidone / Q000737:chemistry; D012834:Silver / Q000633:toxicity*; D013499:Surface Properties; D018675:Toxicity Tests
chemical_list: D019343:Citric Acid; D012834:Silver; D011205:Povidone
keywords: Anaerobic digestion; Anaerobic toxicity; Dissolution; Silver nanoparticles; Stabilization mechanism