Recent studies of estuary environments show that engineered nanoparticles are much more concentrated in films of bacteria, or biofilms, within estuaries than in the surrounding environment. Engineered nanoparticles, when exposed to complex ecosystems, have the potential to cause unintended ecological effects. Many of the predictive models currently used to quantify nanoparticle accumulation in these biofilms fail to account for the effects that charged nanoparticles have on the charged outer matrices of biofilms. To account for charge interactions, a model was developed to predict the mass-transfer rate of nanoparticles into hydrogels, which effectively function as uncharged biofilms, as well as charged biofilms. This model builds on previous models by accounting for nanoparticle diffusivity through hydrogels as well as the binding of species to the external fiber matrix of the hydrogel. In order to verify this model, quantum dot tracers were observed as they diffused into both uncharged hydrogels and charged biofilms. The data was then fit to determine the mass-transfer rate. Knowing the mass transfer rate will allow us to quantify nanoparticle accumulation and ultimately determine the impact of particle diffusivity and surface charge on nanoparticle accumulation in estuarine biofilms. Current research on quantifying nanoparticle ecotoxicity is sparse and the current regulations on nanoparticle disposal are limited, so the results of this investigation could potentially inform new regulations regarding the release of engineered nanoparticles into the environment.
Team Members: Joshua Prince (Team Lead), Daniel Tento