Presenter Information

Claire WalliFollow

Presentation Title

The Toxicity and Kinetics of Silver Nanoparticles in Toxicological Media

Presentation Type

Oral Presentation

Abstract

Silver nanoparticles (AgNPs) are increasing in presence in commercial and medical products due to their bactericidal properties. Aqueous silver (Ag+) toxicity to freshwater organisms has been well studied using the Biotic Ligand Model (BLM), a model that predicts metal toxicity at reactive biological surfaces of freshwater organisms in relation to their surrounding water chemistry. Although dissolved Ag+ from the AgNP surface is still being debated as the toxic mechanism of action of AgNPs, toxicity via ionic dissolution from AgNPs is not accurately predicted by the BLM, which suggests the existence of other or additional chemical or biological reactions in effect. The purpose of this research is to observe the effects of the major freshwater ions calcium (Ca2+), sodium (Na+), chloride (Cl-), and sulfate (SO42-) on the toxicity of AgNPs to the freshwater daphnid, Daphnia magna. These ions have been proven to change the kinetic behavior of the AgNPs by increasing freshwater concentrations of Ag+ via ionic dissolution of the particles or, contrarily, reducing the reactive surface area of the particles as they aggregate and sediment out of a water column. This study used 8 acute toxicity tests performed in ASTM moderately hard synthetic freshwater that had varying additions of Ca2+, Na+, Cl-, and SO42-. These tests have shown that both the mechanisms of the BLM and nanoparticle kinetics influence toxicity seen in significant differences between AgNP LC50s in experimental freshwaters with higher concentrations of higher valency ions. Factorial analysis is used to compare AgNP toxicity to the BLM predictions for Ag+ toxicity as well as different particle behaviors, measured using single particle inductively coupled plasma-mass spectrometry (spICP-MS), dynamic light scattering (DLS) and UV-Vis spectrophotometry. This research aims to further inform the debate about the toxic mechanism of action for AgNPs, as well as understand the impact of specific major ions in freshwater ecosystems on the environmental toxicity of AgNPs.

Start Date

10-5-2018 10:00 AM

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May 10th, 10:00 AM

The Toxicity and Kinetics of Silver Nanoparticles in Toxicological Media

Silver nanoparticles (AgNPs) are increasing in presence in commercial and medical products due to their bactericidal properties. Aqueous silver (Ag+) toxicity to freshwater organisms has been well studied using the Biotic Ligand Model (BLM), a model that predicts metal toxicity at reactive biological surfaces of freshwater organisms in relation to their surrounding water chemistry. Although dissolved Ag+ from the AgNP surface is still being debated as the toxic mechanism of action of AgNPs, toxicity via ionic dissolution from AgNPs is not accurately predicted by the BLM, which suggests the existence of other or additional chemical or biological reactions in effect. The purpose of this research is to observe the effects of the major freshwater ions calcium (Ca2+), sodium (Na+), chloride (Cl-), and sulfate (SO42-) on the toxicity of AgNPs to the freshwater daphnid, Daphnia magna. These ions have been proven to change the kinetic behavior of the AgNPs by increasing freshwater concentrations of Ag+ via ionic dissolution of the particles or, contrarily, reducing the reactive surface area of the particles as they aggregate and sediment out of a water column. This study used 8 acute toxicity tests performed in ASTM moderately hard synthetic freshwater that had varying additions of Ca2+, Na+, Cl-, and SO42-. These tests have shown that both the mechanisms of the BLM and nanoparticle kinetics influence toxicity seen in significant differences between AgNP LC50s in experimental freshwaters with higher concentrations of higher valency ions. Factorial analysis is used to compare AgNP toxicity to the BLM predictions for Ag+ toxicity as well as different particle behaviors, measured using single particle inductively coupled plasma-mass spectrometry (spICP-MS), dynamic light scattering (DLS) and UV-Vis spectrophotometry. This research aims to further inform the debate about the toxic mechanism of action for AgNPs, as well as understand the impact of specific major ions in freshwater ecosystems on the environmental toxicity of AgNPs.