The complexity of real-world Particulate Matter (PM) has been challenging the toxicity evaluation. To address these difficulties, this thesis introduces a feasible approach: the generation of artificial ultrafine PM (PM0.1) for application toward cytotoxicity investigation. Three distinct types of PM0.1 were generated which represented three sources: (1) Exhaust, (2) Non-exhaust, and (3) atmospheric nanoplastics (NPs).
First, the research focused on selecting carbon-based materials to synthesize artificial Black Carbon (aBC), a predominant constituent of atmospheric PM primarily originating from exhaust emissions. The controllable surface oxidation state of aBC reveals the correlation of the oxygenated functional group with the ROS-producing level of the A549 cell.
Second, due to the increase of non-exhaust emission fraction to total PM emission, Tire Wear Particles (TWP) are generated by mechanical abrasion as non-exhaust PM. Beyond the environmental implications of microplastic contributions, our findings revealed the potential release of ZnO-CB nanoparticles from TWP to the environment. Therefore, to simulate the leachate originated from TWP, ZnO-CB nanoparticles were synthesized and aerosolized for Air Liquid Interface exposure.
Third, the attention of TWP links our research to airborne NPs. Adopting the condensation mechanism of particle formation via the thermal process of plastic, the plastic extruder method was selected for NPs generation. The existence of NPs, was confirmed by surface-enhanced Raman spectroscopy, was then applied to Air Liquid Interface experiment with co-cell culture techniques. The increase in cytotoxicity and inflammatory response suggests the potential acute toxicity of the generated ABS NPs.