The rapid growth of consumer products containing engineered nanoparticles requires timely research into the health and environmental impacts of these nanomaterials to ensure their sustainable manufacture, use, and disposal. We have evaluated the impacts of water suspensions of carbon-containing nC60, and metal-containing quantum dots on microorganisms. Our previous work showed that nC60 suspensions display antibacterial properties, and, in the past year, we determined that the antibacterial activity of nC60 was due to direct protein oxidation and not production of ROS as previously inferred by other researchers. In separate studies, quantum dots (QDs) were evaluated for antibacterial and antifungal activities. QDs consist of a heavy metal-containing reactive core, which is coated with organics to make QDs water-stable and biocompatible. We found that the organic coating could be easily degraded (i.e., weathered) at non-neutral pH, leading to the release of toxic metals, which caused bacterial and fungal mortality. Proteins, ligands, and natural organic matter (NOM) effectively decreased the toxicity of weathered QDs. We also investigated phytotoxicity of metal-oxide nanoparticles – aluminum oxide, silicon dioxide, zinc oxide, and iron oxides – on Arabidopsis thaliana, a model plant, showing that the adverse effect of these nanoparticles on A. thaliana growth and development are due only in part to their release of toxic ions. Future research directions include further assessment of relevant environmental-fullerene chemistries (specifically, biotransformation and bioaccumulation of fullerenes in environmental systems) and impacts of other metallic nanomaterials, such as quantum dots and Au/Sn nanoparticles, on microbial communities and ecosystem functions.
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