Quantifying the adsorption of ionic silver and functionalized nanoparticles during ecotoxicity testing: Test...

Area of Science:

• Environmental Science
• Nanotoxicology
• Ecotoxicology

Background:

• Silver nanoparticles (Ag-NPs) are widely used, raising environmental safety concerns.
• Differentiating Ag-NP toxicity from released ionic silver (Ag) toxicity is challenging due to silver's reactivity.
• Silver's adsorption and photoreduction in solutions complicate accurate toxicity assessments.

Purpose of the Study:

• To quantify silver loss during ecotoxicity testing of Ag-NPs and dissolved Ag.
• To assess the impact of container materials and geometries on silver loss.
• To evaluate Ag-NP loss from solutions and its dependence on surface functionality.

Main Methods:

• Utilized a sensitive (110m)Ag isotope tracing method to quantify silver loss.
• Conducted standard ecotoxicity tests with the green alga Pseudokirchneriella subcapitata.
• Investigated silver loss using various test container materials and geometries.
• Examined surface-functionalized Ag-NPs under standard algal growth inhibition test conditions.

Main Results:

• Substantial underestimation of dissolved Ag toxicity to Pseudokirchneriella subcapitata when based solely on initial concentrations.
• Significant Ag-NP loss from test solutions due to adsorption onto container walls.
• Ag-NP loss was dependent on the specific surface-functionality of the nanoparticles.
• Losses occurred across different test container materials and geometries.

Conclusions:

• Standard ecotoxicity testing protocols may significantly underestimate Ag-NP and dissolved Ag toxicity.
• Experimental design must account for silver loss via adsorption and other mechanisms.
• Findings are crucial for accurate nanotoxicology assessments of Ag-NPs and other nanoparticles.