Spectroscopic Measurements of Oxide Nanoparticles in Aqueous Environments as a Probe of Nano-Bio Interactions and Nanoconfinement
Nanoparticles are commonly found in everyday life ranging from additives in consumer products to naturally occurring minerals. Despite being either engineered or naturally occurring, these nanoparticles often interact with environmental aqueous systems that are rich in biomolecules or can be internalized into the human body to encounter biological fluids. Adsorption of biomolecules onto nanoparticle surfaces often changes physicochemical properties, reflecting properties of adsorbed components rather than the nanoparticle. These property changes can influence intermolecular interactions and reduce the number of free molecules in solution, restricting bioavailability. Moreover, the adsorption process can change protein and DNA conformation where misfolded structures can lead to diseases such as, Alzheimer’s and Creutzfeldt-Jakob disease. As these nanoparticle-biological complexes move through different biomes, variations in pH and temperature or exposure to nanoscale confinement can occur. The changes to surrounding conditions can further alter the adsorbed composition, biomolecule structure, and nanoparticle physicochemical properties. To predict the fate of these dynamic processes in a multicomponent system, it is necessary to understand the detailed surface chemistry occurring at the nano-bio interface. This dissertation aims to probe the effects of environmental conditions on the stability and persistence of biomolecules and small organic acids on metal oxide nanoparticles and within metal oxide nanoscale pores. These interactions are probed using vibrational spectroscopy as well as other complementary spectroscopic and microscopic techniques. The results from this dissertation provide insights into metal oxide nanoparticle surface chemistry and nanoscale confinement to better understand nano-bio interactions over a range of environmental conditions.