title: Challenges for physical characterization of silver nanoparticles under pristine and environmentally relevant conditions.
abstract: The reported size distribution of silver nanoparticles (AgNPs) is strongly affected by the underlying measurement method, agglomeration state, and dispersion conditions. A selection of AgNP materials with vendor-reported diameters ranging from 1 nm to 100 nm, various size distributions, and biocompatible capping agents including citrate, starch and polyvinylpyrrolidone were studied. AgNPs were diluted with either deionized water, moderately hard reconstituted water, or moderately hard reconstituted water containing natural organic matter. Rigorous physico-chemical characterization by consensus methods and protocols where available enables an understanding of how the underlying measurement method impacts the reported size measurements, which in turn provides a more complete understanding of the state (size, size distribution, agglomeration, etc.) of the AgNPs with respect to the dispersion conditions. An approach to developing routine screening is also presented.
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8520, USA. robert.maccuspie@nist.gov
authors.forename: Robert I
authors.initials: RI
authors.lastname: MacCuspie
authors.forename: Kim
authors.initials: K
authors.lastname: Rogers
authors.forename: Manomita
authors.initials: M
authors.lastname: Patra
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Suo
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Allen
authors.forename: Matthew N
authors.initials: MN
authors.lastname: Martin
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Hackley
mesh_terms: D000327:Adsorption; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000032:analysis / Q000737:chemistry*; D010316:Particle Size; D012834:Silver / Q000032:analysis / Q000737:chemistry*; D055814:Wilderness
chemical_list: D004785:Environmental Pollutants; D012834:Silver