Silver nanoparticles are extensively used for their antimicrobial properties in an increasing number of consumer and commercial products as well as in wastewater treatment. Understanding the potential toxicity and environmental impacts of silver nanoparticles is challenging. Because silver nanoparticles undergo ionic dissolution, discrepancies exist over the relative contribution of silver ions or the nanoparticles themselves in toxicity. This project will increase understanding of how silver nanoparticle properties affect bio-uptake, nanoparticle-biological interactions, and ecotoxicity. Effects of particle surface oxidation and ionic dissolution, which have complicated toxicity studies in the past, will be eliminated. This study will identify properties of silver nanoparticles that make them ecologically disruptive leading to adverse environmental outcomes. All data will be shared through the open-source knowledge base of Nanomaterial-Biological Interactions (NBI) globally for modeling efforts and will support the development of safety protocols, exposure guidelines, and regulations that protect human and ecosystem health. Furthermore, this research will provide design rules for the assembly of new classes of silver nanoparticles that could be commercialized without concern regarding rapid particle degradation and release into the environment. In addition, this project is designed to incorporate students from diverse backgrounds and will help build future science, technology, engineering and math (STEM) talent.
The researcher's overall aim is to improve our understanding of the specific physiochemical features that dictate nanoparticle-biological interactions. First, they will design a series of lipid-coated silver nanoparticles that are differentially shielded from ion dissolution. Differentially shielded silver nanoparticles will be prepared by encapsulating silver nanoparticles of varying size and shape with a hybrid lipid-membrane to protect the surface from oxidation and ionic dissolution. Changes in the localized surface plasmon resonance (LSPR), thermal electron microscope (TEM), and (Inductively-coupled plasma mass spectrometer (ICP-MS) will be employed to monitor silver ion dissolution from the suite of nanoparticles. Second, they will identify features of lipid-coated nanoparticles that lead to particle instability. The agglomeration kinetics of the hybrid lipid-coated silver nanoparticles will be assessed using dynamic light scattering and nanoparticle tracking analysis. Third, since the goal is to ultimately relate these material features with nanoparticle-biological interactions, the researchers will determine the uptake and toxicity of the silver nanoparticle suite. Based on preliminary investigations, the hybrid lipid-coated silver nanoparticles with a robust coating should elicit minimal toxicity and a decrease in surface coverage should lead to a respective increase in toxicity. A well-established embryonic zebrafish assay will be used to identify vertebrate morbidity and mortality resulting from exposure and hyperspectral imaging (HSI) will be used to visualize nanoparticle uptake in whole animals. Finally, the researchers will assess the potential ecotoxicity of the suite using a novel nanocosm assay. Hyperspectral imaging will be used to visualize nanoparticle biodistribution among bacteria, algae, crustaceans, and fish in the small-scale freshwater assay. Collectively, the use of well-characterized silver nanoparticles tuned for ion release will allow the PIs to tease apart the relative contribution of the nanoparticle and ion to biouptake, toxicity, and potential for environmental impacts.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
