Figure 2.

Toxicity of Co₃O₄ particles on BEAS-2B and NHBE primary cells. CellTiter-Glo assay (ATP measurement) (A). BEAS-2B cells were exposed to Co₃O₄ particles (0 – 1000 μg.mL⁻¹ Co), latex beads LB-3 (0 – 1000 μg.mL⁻¹) as a negative control, or soluble cobalt (CoCl₂) for 72 h (0 – 50 μg.mL⁻¹ Co). The cellular ATP content was then evaluated (RLU, Relative Light Unit). Results were obtained from a minimum of three independent experiments, each performed in quadruplicate. Clonogenic assay (proliferation) (B). Example of Co₃O₄ particle effects on colony formation of BEAS-2B cells (μg.mL⁻¹ Co). Colony numbers were determined following a 24 h exposure to Co₃O₄ particles and LB-3 (0 – 1000 μg.mL⁻¹ Co and LB-3, respectively) and ten days of culture (time period needed to form colonies). Results were obtained from three to six biological replicates. IC50 (μg.mL⁻¹ Co and LB-3, respectively) values obtained after exposure of BEAS-2B and NHBE cells to Co₃O₄ particles and latex beads (C).