Doctor of Philosophy (PhD)
Environmentally persistent free radicals (EPFRs)—a newly discovered pollutant associated with particulate matter (PM)—form during combustion and thermal processes, such as the incineration of hazardous waste. Various chlorine- and hydroxy-substituted benzenes chemisorb on the surface of metal oxides (e.g., NiO, CuO, and Fe2O3) and then form EPFRs, stabilized radical species, as the result of the transfer of electrons between the adsorbate and the metal ion of the metal oxide. Previous studies have shown direct correlations between ultra-fine (d < 0.1 mm) particulate matter (PM0.1) exposure and adverse pulmonary health effects. PM0.1 has the potential to reach deep into the alveoli of the lungs, and it is hypothesized that uptake of EPFR/PM by or its interaction with cells is the probable cause of such health effects. To investigate the effect of EPFR/PM on pulmonary epithelial cells, highly fluorescent surrogate EPFR probe-based upconverting nanoparticles (UCNPs) were synthesized based on NaYbGdF4:Er. The latter are unique photo-luminescent materials, because of their ability to be excited with near-infrared (NIR) radiation, with subsequent emission of visible light. UCNPs show great potential for cellular imaging due to their NIR excitation, which allows for higher penetration depth of the excitation radiation, minimal interfering absorption and fluorescence from the biological environment, and fewer adverse effects on cells. These emissive materials have been transformed via several surface modifications to yield a ~100-nm first-generation fluorescent EPFR/PM0.1 surrogate. Current research focuses on exploring the final destination of these fluorescent EPFR/PM0.1 surrogates upon their exposure to human BEAS-2B lung cells and understanding how the trackable surrogates alter cellular function. Presented here is work on the synthesis, characterization, and investigation of EPFR surrogates and their ability to affect cellular oxidative stress, their cytotoxicity, and the final fate of such materials in the cellular environment.
Badgett, Ansonia, "Toward the Impact of Particulate Matter in Human Health: Evaluation of Fluorescent Environmentally Persistent Free Radical (EPFR) Surrogates" (2019). LSU Doctoral Dissertations. 4790.
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