Physicochemical surface and bulk properties of metal and metal oxide nanomaterials in gaseous and liquid phases: Implications of fate, transport and pulmonary toxicity

Metal and metal oxide nanomaterials have been shown to possess superior properties to their bulk counterparts and are being used in a myriad of applications. There has been continual growth of commercial and industrial products that incorporate metal and metal oxide nanomaterials because of their unique electronic, magnetic or thermodynamic properties. The growing integration of nanomaterials into products makes it necessary to understand the risks associated with the fate, processing, transport and toxicity of these materials. The nanoparticle size can affect both physical and chemical properties of the materials, especially < 10 nm, and we surmised that the change in physicochemical properties would also change their impact on biological and natural systems. The work reported herein has been aimed at characterizing metal and metal oxides nanoparticles and examining the differences in reactivity. Fate and processing of metal and metal oxide nanomaterials was examined in simulated biological and natural systems with collaborators studying the pulmonary inflammatory responses in mouse models. Both goals were specifically designed to examine how physicochemical properties (focusing on surface reactivity and structure) change as a function of size. The toxicity studies were pioneering because expertise in nanoparticle characterization was combined with expertise in toxicity. The collaboration allowed physicochemical properties to be related to biological markers to make more detailed assessments.;The examination of the size dependent nature of nanomaterials in natural environments with different FTIR techniques was used as a main analytical tool for examining the surface interactions on nanomaterials in both gaseous and liquid phases. Macroscopic studies were also conducted on the dissolution of the metal and metal oxide nanomaterials as function of pH, ionic strength, types and concentration of ligands. These factors strongly correlate to the state of the nanomaterial, i.e. are the nanoparticles isolated, aggregated or dissolved into metal ions? The effects of aggregation can have a large impact on their physicochemical properties. The research adds to the scientific understanding of the fate and processing of nanomaterials in different environmental and biologically relevant systems which can be used to make model predictions for future nanomaterials about risk of exposure.