In conjunction with other investigators from the Center for the Environmental Implications for NanoTechnology (CEINT), the Di Giulio lab has been investigating the ecotoxicity of various nanomaterials in fish and nematode models. Nanoparticles (two dimensions <100 nm) and nanomaterials (one dimension <100 nm) are becoming ubiquitous additions to everyday products because of the special optical, electrical, structural, or anti-microbial properties that their macro relatives do not possess. Most nanomaterials are either metal or metal oxide based (silver, titanium dioxide, cerium oxides, quantum dots) or are carbon based (fullerines, carbon nanotubes, carbon nanofibers).
Since nanotechnology is progressing at such a fast pace and nanomaterials are being incorportated into new products every day, it is important that we fully understand the implications for their ultimate and unavoidable release into the environment. Unfortunately, one of the take away messages from the last decade or so of nano research is that the vast array of different nanomaterials with different shapes, sizes, coatings, and dispersions act differently from each other making it difficult to extrapolate environmental consequences from studying just a few of them.
TiO2 Nanoparticles and PAH Mixtures
Titanium dioxide nanoparticles are commonly used as a photocatalyst and as a UV-attenuator in products such as sunscreens, plastics, and cleaning solutions due to their photo-reactive properties. They are also being heavily investigated for use as a remediation aid at sites contaminated with organic compounds such as pesticides, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), although no research to date has investigated whether TiO2 NPs actually reduce contaminant toxicity in vivo. Goals of this research are to use developing zebrafish and adult mosquitofish under environmentally relevant conditions to determine how TiO2 NPs affect the toxicity and the degradation of natural PAH mixtures under sunlight in the laboratory and using mesocosms.
Silver Nanoparticles in Environmental Media
The increasing use of silver nanoparticles (AgNPs) as antimicrobials in consumer products and industrial applications has raised concern over their inevitable release into the aquatic environment. In order to better understand the fate and toxicity of AgNPs in the context of release into aquatic ecosystems, the Di Giulio laboratory has participated in the CEINT-wide freshwater wetland mesocosm projects investigating the long-term ecosystem effects of AgNPs. In particular, we are interested in the uptake, maternal transfer, and effects of AgNPs on mosquitofish present in these mesocosms. In addition, we have employed a microcosm approach to incorporating more environmental variables into laboratory toxicity experiments.
Risk Assessment of Nanocomposites
Together with NIST, CPSC, and CEINT, we are performing a risk assessment of nanocomposites created as flame retardants. Nanocomposites, macro materials with embedded nanomaterials, are some of the most likely vectors for nanos into the consumer realm and therefore into the environment. We are studying the overall toxicity and release of the nanomaterial portion from various thermoplastics embedded with various nanomaterials (including CNF, left), as well as polyurethane foams coated with various nanomaterials. For this project we are using the model nematode, C. elegans, and the zebrafish, Danio rerio.