Erm cz100

FD (ERM-CZ100)—a road dust originating from the Wislostor ada road tunnel in Warsaw, Poland—was purchased from Sigma-Aldrich (St. Louis, MO, USA). It is the dust collected from a tunnel in Warsaw, Poland. It is certified for the mass fraction of selected polycyclic aromatic hydrocarbons and contains different particle sizes. A stock solution of FD was prepared in dimethyl sulfoxide (DMSO). A working concentration of FD was prepared by further diluting a stock solution of FD in medium. The concentration of FD was always maintained equivalently throughout the experiment.

The airborne FDPs reference material ERM-CZ100 (smaller than 10 μm) and the pure catechin compounds EGCG, epigallocatechin (EGC), epicatechin (EC), and epicatechin gallate (ECG) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Phenolic compounds, quercetin, kaempferol, and myricetin were also obtained from Sigma-Aldrich. Dried green tea leaves (Osulloc Farm, Jeju Island, Korea) were obtained, extracted, and purified for the preparation of GTE, FLGs, and CTPs. All other chemicals used in this study were of analytical grade.
ERM-CZ100 was suspended in serum-free DMEM and homogenized by sonication to make a 10 mg/ml stock solution. Phosphate-buffered saline (PBS), dimethyl sulfoxide (DMSO), and the fluorescent probe 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) were purchased from Sigma-Aldrich. MitoSOX Red (M36008) was obtained from Thermo Fisher Scientific (Indianapolis, IN, USA), and an MTT assay kit and a Cell Counting Kit-8 were purchased from Dojindo (Kumamoto, Japan).

PM_2.5 was obtained by separating PM₁₀ certified reference material (i.e., ERM-CZ100) using a modified sedimentation method [40 (link)]. First, 500 mg of ERM-CZ100 (Sigma-Aldrich, St. Louis, MO, USA) was dispersed in 100 mL of 99.9% anhydrous ethanol (Samchun Chemicals, Seoul, Republic of Korea) and sonicated (DH.WUC. A03H, Daihan Scientific, Daegu, Republic of Korea) for 15 min. The sonicated PM₁₀ solution was sedimented at room temperature for 30 min. To separate PM_2.5 and solvent, 50 mL of the supernatant was centrifuged at 3220 x g for 5 min (Centrifuge 5810, Eppendorf, Hamburg, Germany). After removing the supernatant, the PM_2.5 was collected in a glass vial and dried at 80 °C in a vacuum oven to remove residual ethanol.
CSE was prepared as described previously [41 (link)]. Briefly, the smoke from 4 cigarettes (Camel, R. J. Reynolds Tobacco Company) was drawn into a glass syringe containing 50 ml serum-free RPMI 1640 medium (Welgene, Gyeongsan, Republic of Korea). The preparation was deemed 100% CSE. A 3% working solution was prepared by diluting the stock with culture medium and the remaining stock was stored at -80 ℃.