AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Collection Methods Affect the Physicochemical Properties of Combustion Particles and Their Cellular Response in a Human Macrophage-Like Cell Line
KAMALJEET KAUR, Isabel C. Jaramillo, Raziye Mohammadpour, Anne Sturrock, Hamid Ghandehari, Chris Reilly, Robert Paine, Kerry Kelly, University of Utah
Abstract Number: 115 Working Group: Health-Related Aerosols
Abstract A vast majority of in vitro studies expose cells to combustion-derived particulate matter (cdPM) in a suspension, which requires a method to collect cdPM and subsequent resuspension in an aqueous media. The consequences of different particle collection methods on particle physiochemical properties and resulting cellular responses are not fully understood. This study compared the physicochemical properties and cellular response in human macrophage (THP-1) for cdPM collected by three different methods. These collection methods included two common approaches (collection on a 200-nm PTFE filter followed by resuspension in DI water, and collection on a cold plate followed by scraping and resuspension in DI water) and one relatively new (direct bubbling in DI water) approach. All approaches used cdPM produced from a jet-fuel surrogate burned in a flat-flame burner under constant combustion conditions. The three approaches yielded cdPM with differences in particle size distribution, surface area, the presence of dissolved species, and oxidative potential. Among the collection methods, only the directly bubbled sample retained the bimodal distribution observed in the gas-phase. The directly bubbled sample suspension had the smallest mean radius (root mean square, rms, of 48.7 nm), followed by filtered (57.4 nm) and scraped (85.0 nm) sample. The bubbled sample contained ~50 % of its total mass as dissolved species and lower molecular weight compounds that were not found in the other two samples. These differences in the cdPM physicochemical properties affected the biological responses in THP-1 cells. The bubbled sample showed greater oxidative potential and cellular reactive oxygen species. The scraped sample induced the greatest inflammatory response (TNFα secretion). These findings have important implications for in vitro studies of air pollution and for efforts to better understand the underlying mechanism.