Studies of nanoparticle (NP) toxicity to the environment often come up with contradictory results. For example, nanoparticles (NPs) have demonstrable negative impact on aquatic organisms, but divergent results have been reported on the role of NP size on their toxicity. The PI and Co-PIs hypothesize that such contradictory evidence is most likely due to the heterogeneity and polydispersity of the NPs themselves. They hypothesize that polydispersity can cause incorrect measurement of NP properties and lead to an underestimation of NP dose, particularly if the toxic effects are only due to a sub-fraction of the polydisperse suspensions. The proposal will specifically investigate the effect of NP dispersity on their properties and on their toxicities, investigating such NP properties as size, dispersity, morphology, and facet exposure, and their effect in nanotoxicity. The results of this project will help improve the design of NPs by identifying features that can induce deleterious effects, and also help Understand the fate, behavior, uptake, and toxicity of NPs. Progress in this area will aid a sustainable development of nanotechnology and its benefits. Under this proposal's plan, the PIs will work directly with K-12 institutions and underrepresented minorities (URMs) in South Carolina and produce distance-learning materials for wider outreach. The PIs have a strong track record of ensuring inclusion of under-represented groups in training and outreach activities and will recruit for the PhD candidate with outreach principles in mind. The University of South Carolina has one of the highest numbers of African American students for a Carnegie One research intensive university (13%).
To achieve their goals, the PIs must first rigorously characterize the NPs they synthesize and then correlate the various properties of the NPs with their observed toxicities. To that end, the PIs will seek to establish a reproducible protocol for the synthesis of poly- and mono-dispersed NPs and their separation into a set of monodisperse subfractions. They will then characterize the NPs (e.g., size, dispersity, morphology, facets) using a multi-method approach and quantify the uptake and toxicity of polydisperse versus monodisperse subfractions of NPs using the standardized polyhaline estuarine copepod model, Amphiascus tenuiremis.
With this approach, the PI and Co-PIs seek to provide a methodology that can be widely used by the scientific community for similar and other studies, as well as in other fields such as drug delivery, where NP size dispersity has been realized as an issue of confounding results in the literature.
