title: Characterization of silver nanoparticle aggregates using single particle-inductively coupled plasma-mass spectrometry (spICP-MS).
abstract: The single particle-inductively coupled plasma-mass spectrometry was applied to characterize the aggregates of AgNPs. was applied to characterize the aggregates of AgNPs. Two sizes of citrate-AgNPs and PVP-AgNPs were used at relatively high and predicted environmental concentrations under various ionic strengths. Citrate-AgNP aggregated with increases in the ionic strength, whereas PVP-AgNPs were sterically stable. The critical coagulation concentrations were 85 mM and 100 mM NaNO3for 60 nm and 100 nm citrate-AgNPs at 2 mg L-1as total Ag obtained by dynamic light scattering (DLS). At 2 mg L-1as total Ag, the mass of an aggregate gradually increased with increasing ionic strength for both citrate-AgNP during spICP-MS analyses. The average number of single particles derived from the mass in an aggregate was calculated to be 8.68 and 5.95 for 60 nm and 100 nm citrate-AgNPs at 85 mM and 100 mM NaNO3, respectively after 2 h. The mass fractal dimensions were determined to be 2.97 and 2.83, further implying that the aggregate structures were very rigid and compact. Only marginal increases in the average mass and number of single particles in the aggregate units were found during 24 h under environmentally relevant AgNP concentrations. The average number of single particles constituting an aggregate unit for 60 nm and 100 nm citrate-AgNPs was 1.24 and 1.37 after 24 h at a high ionic strength. These results indicate that under environmentally relevant conditions, the collision frequency is predominant in the aggregation and that NPs are likely to encounter natural colloids such as clay and organic matter to form hetero-aggregates.
authors.affiliation: School of Earth and Environmental Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, Republic of Korea.
authors.forename: Hyun-A
authors.initials: HA
authors.lastname: Kim
authors.affiliation: School of Earth and Environmental Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, Republic of Korea. Electronic address: btlee@gist.ac.kr.
authors.forename: Byung-Tae
authors.initials: BT
authors.lastname: Lee
authors.affiliation: School of Earth and Environmental Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, Republic of Korea.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Na
authors.affiliation: School of Earth and Environmental Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, Republic of Korea. Electronic address: kwkim@gist.ac.kr.
authors.forename: Kyoung-Woong
authors.initials: KW
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO, United States.
authors.forename: James F
authors.initials: JF
authors.lastname: Ranville
authors.affiliation: Department of Geology and Research Institute of Natural Science, Gyeongsang National University, Jinju, Republic of Korea.
authors.forename: Soon-Oh
authors.initials: SO
authors.lastname: Kim
authors.affiliation: Division of Risk Assessment, Department of Environmental Health Research, National Institute of Environmental Research, Incheon, Republic of Korea.
authors.forename: Eunhye
authors.initials: E
authors.lastname: Jo
authors.affiliation: Division of Risk Assessment, Department of Environmental Health Research, National Institute of Environmental Research, Incheon, Republic of Korea.
authors.forename: Ig-Chun
authors.initials: IC
authors.lastname: Eom
mesh_terms: D019343:Citric Acid / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods; D053768:Metal Nanoparticles / Q000737:chemistry*; D011205:Povidone / Q000737:chemistry; D012834:Silver / Q000737:chemistry*
chemical_list: D019343:Citric Acid; D012834:Silver; D011205:Povidone
keywords: Aggregate structure; Aggregation; Environmentally relevant concentrations; Silver nanoparticles (AgNPs); Single particle-ICP-MS (spICP-MS)