(174a) Effect of Combustion Particle Morphology on the Cellular Response in Human Airway Epithelial Cells and Macrophage-like Cells

Atmospheric aging changes the morphology of newly formed (fresh) soot particles from a fiber-like to compact spherical aggregate. In addition, fresh soot is hydrophobic, but with atmospheric aging the surface of soot becomes more hydrophilic. This hydrophilic nature allows water uptake, which later exerts capillary forces between primary particles of the agglomerate, causing the structure to collapse and become more compact. The effect of this morphology change on cellular toxicity is unknown. This study aims to study the effect of the morphology on cellular behavior in airway epithelial cells (A549) and macrophage-like cells (THP-1). A method based on water condensation and evaporation was developed to change the morphology of agglomerates from fiber-like to compact spherical, without affecting the chemical composition. The particles with the two different morphologies are deposited directly on the cells using an electrostatic based air-liquid interface (ALI) exposure system. The mass deposition in the ALI system is monitored in real time using a quartz crystal microbalance. We hypothesize that the fiber-like particles will induce a greater reactive oxidation species, pro-inflammatory, and apoptotic response. The possible reason would be the higher surface area of these particles, which will allow a higher interaction with the cell membrane and better uptake.