The growing use of engineered nanoparticles (NPs) in industrial and medical applications is expected to increase unintended environmental or occupational exposures and intended medical or direct consumer exposures. The physical and chemical properties of the NPs engage and activate distinct proteins and cellular pathways that, in turn, govern the impact of the NPs on the cell and ultimately on human health. The relationship between particle properties and these complex cellular processes and responses are still unclear. The difficulty in identifying these relationships is partially due to the strong tendency of NPs to acquire different properties in different environments. To better understand these relationships in the intracellular environment, we employ approaches that allow us to determine physical and chemical properties of the NPs inside intact cells and organelles. Here we describe changes in properties of zinc oxide NPs (ZNPs) and ceria NPs (CNPs) inside the cytoplasm and organelles of intact alveolar epithelial cells, which present a vulnerable target for airborne inhaled NPs. Using a highly sensitive fluorescent indicator for zinc ions, we quantified the dissolution dynamics that airborne ZNPs, deposited intact at the cell surface-air interface, undergo inside distinct organelles. We show that the impact on the cell is highly dependent on the type of organelles in which the dissolution occurs. We also describe the development of a correlated x-ray (STXM) and super resolution fluorescence (SIM) microscopy to study the changes in the oxidation state of CNPs inside organelles in intact cells. We show a clear shift to a higher Ce3+ content in NPs that enter the cellular environment and point to possible interactions that might underlie the cellular response.

Changes in nanoparticle properties detected inside organelles using high resolution fluorescence and X-ray microscopy in intact hydrated cells

248th National Meeting (2014)

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