Presentation Title

The Influence of Major Freshwater Ions on the Bioavailability of Silver Nanoparticles to Daphnia magna

Presentation Type

Poster

Abstract

Silver nanoparticles (AgNPs) are increasing in presence in commercial and medical products due to their bactericidal properties. When materials containing AgNPs are washed, traces of them are transported through wastewater treatment facilities and into the environment. Once there, they may have toxic effects on aquatic organisms. These organisms are extremely sensitive to the water chemistry of the environment in which they live. Chemicals present can react with sensitive areas on the organism where important biochemical reactions occur. In aquatic toxicology, these reactive areas are referred to as the biotic ligand and have been well studied as the locations where metals in solution bind to and cause toxicity. Major cations in freshwater, such as Na+ and Ca2+, compete with the metal ions for binding sites at the biotic ligand, reducing the concentration of metal at the site of toxicity and decreasing the toxic effect. The bioavailability of silver ions (Ag+) that have dissociated from AgNPs can be modeled using the biotic ligand model (BLM).

Freshwater ions have also been proven to strongly impact AgNP behavior by affecting the rates of Ag+ dissolution from the particle surface, or inducing aggregation of particles causing them to sediment. Changes in particle behavior have been proven to alter the toxicity of AgNPs. Dissolution of Ag+ from the AgNP surface is argued to be the toxic mechanism of action of AgNP, however, the toxicity of AgNPs is not entirely predictable by the BLM and the reason why is still being debated. The purpose of my research is to observe the effects of individual freshwater ions on the toxicity of AgNPs to the freshwater daphnid, Daphnia magna. By increasing ion concentrations to standardized synthetic freshwater, I will create 8 water types with measured ion concentrations. I will then compare AgNP toxicity to the daphnid to alterations in particle characteristics such as particle size and Ag+(aq) concentrations, and to the predictions of the BLM. My project design aims to explain whether differences in toxicity can be explained by changes in the behavior of the nanoparticles or are instead due to protection against or exacerbation of toxicity of dissolved Ag+ at the biotic ligand.

Start Date

6-5-2017 12:15 PM

End Date

6-5-2017 2:00 PM

Location

Miller Hall

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May 6th, 12:15 PM May 6th, 2:00 PM

The Influence of Major Freshwater Ions on the Bioavailability of Silver Nanoparticles to Daphnia magna

Miller Hall

Silver nanoparticles (AgNPs) are increasing in presence in commercial and medical products due to their bactericidal properties. When materials containing AgNPs are washed, traces of them are transported through wastewater treatment facilities and into the environment. Once there, they may have toxic effects on aquatic organisms. These organisms are extremely sensitive to the water chemistry of the environment in which they live. Chemicals present can react with sensitive areas on the organism where important biochemical reactions occur. In aquatic toxicology, these reactive areas are referred to as the biotic ligand and have been well studied as the locations where metals in solution bind to and cause toxicity. Major cations in freshwater, such as Na+ and Ca2+, compete with the metal ions for binding sites at the biotic ligand, reducing the concentration of metal at the site of toxicity and decreasing the toxic effect. The bioavailability of silver ions (Ag+) that have dissociated from AgNPs can be modeled using the biotic ligand model (BLM).

Freshwater ions have also been proven to strongly impact AgNP behavior by affecting the rates of Ag+ dissolution from the particle surface, or inducing aggregation of particles causing them to sediment. Changes in particle behavior have been proven to alter the toxicity of AgNPs. Dissolution of Ag+ from the AgNP surface is argued to be the toxic mechanism of action of AgNP, however, the toxicity of AgNPs is not entirely predictable by the BLM and the reason why is still being debated. The purpose of my research is to observe the effects of individual freshwater ions on the toxicity of AgNPs to the freshwater daphnid, Daphnia magna. By increasing ion concentrations to standardized synthetic freshwater, I will create 8 water types with measured ion concentrations. I will then compare AgNP toxicity to the daphnid to alterations in particle characteristics such as particle size and Ag+(aq) concentrations, and to the predictions of the BLM. My project design aims to explain whether differences in toxicity can be explained by changes in the behavior of the nanoparticles or are instead due to protection against or exacerbation of toxicity of dissolved Ag+ at the biotic ligand.