Transformation of Engineered Nanomaterials Under Simulated Environmental Conditions.

Once released into the environment, engineered nanomaterials may be transformed by microbially mediated redox processes altering their toxicity and fate. Little information is currently available on engineered nanomaterial transformation under environmentally relevant conditions. We have developed chemical models of important environmental redox processes to investigate nanomaterial transformation (“weathering”) under simulated environmental conditions. One such system is based on the extracellular hydroquinone-driven Fenton chemistry produced by lignolytic fungi. We demonstrate the utility of the assay using functionalized CdSe quantum dots as prototypical nanoparticles. Quantum dot transformation was assessed by UV-Visible spectroscopy, infrared spectroscopy, inductively-coupled plasma-optical emission spectroscopy, dynamic light scattering, transmission electron microscopy, and energy dispersive x-ray spectroscopy. We examined the toxicity to zebrafish embryos of quantum dots before and after simulated environmental “weathering”. Quantum dot transformation under oxidative environmental conditions and concomitant changes in toxicity will be discussed.