title: High-throughput screening of silver nanoparticle stability and bacterial inactivation in aquatic media: influence of specific ions.
abstract: Although silver nanoparticles are being exploited widely in antimicrobial applications, the mechanisms underlying silver nanoparticle antimicrobial properties in environmentally relevant media are not fully understood. The latter point is critical for understanding potential environmental impacts of silver nanoparticles. The aim of this study was to elucidate the influence of inorganic aquatic chemistry on silver nanoparticle stability (aggregation, dissolution, reprecipitation) and bacterial viability. A synthetic "fresh water" matrix was prepared comprising various combinations of cations and anions while maintaining a fixed ionic strength. Aggregation and dissolution of silver nanoparticles was influenced by electrolyte composition; experimentally determined ionic silver concentrations were about half that predicted from a thermodynamic model and about 1000 times lower than the maximum dispersed silver nanoparticle concentration. Antibacterial activity of silver nanoparticles was much lower than Ag(+) ions when compared on the basis of total mass added; however, the actual concentrations of dissolved silver were the same regardless of how silver was introduced. Bacterial inactivation also depended on bacteria cell type (Gram-positive/negative) as well as the hardness and alkalinity of the suspending media. These simple, but systematic studies--enabled by high-throughput screening--reveal the inherent complexity associated with understanding silver nanoparticle antibacterial efficacy as well as potential environmental impacts of silver nanoparticles.
authors.affiliation: Department of Civil and Environmental Engineering, California NanoSystems Institute, and Molecular Screening Shared Resource, University of California, Los Angeles, California 90095, USA.
authors.forename: Xue
authors.initials: X
authors.lastname: Jin
authors.forename: Minghua
authors.initials: M
authors.lastname: Li
authors.forename: Jinwen
authors.initials: J
authors.lastname: Wang
authors.forename: Catalina
authors.initials: C
authors.lastname: Marambio-Jones
authors.forename: Fubing
authors.initials: F
authors.lastname: Peng
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Huang
authors.forename: Robert
authors.initials: R
authors.lastname: Damoiseaux
authors.forename: Eric M V
authors.initials: EM
authors.lastname: Hoek
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects*; D020128:Inhibitory Concentration 50; D053768:Metal Nanoparticles; D009994:Osmolar Concentration; D012834:Silver / Q000737:chemistry*; D012995:Solubility; D013816:Thermodynamics
chemical_list: D000900:Anti-Bacterial Agents; D012834:Silver