Fig. 3.

The effect of ZnO-NPs on cell viability. a Cytolysis of FE1-MML cells. Cell viability was measured using the Trypan blue dye exclusion method. A Concentration–dependent toxicity was observed after exposure for 24 h. However, there was no significant difference between Z-COTE, Z-COTE HP1 and fine ZnO in cell viability after exposure. b Metabolic activity of FE1-MML cells. The MTT assay results confirmed a concentration dependent cytotoxicity (*p < 0.05 vs. control cells; ^# p < 0.05 vs. 6.25 µg/mL; ^† p < 0.05 vs. 12.5 µg/mL; ^‡p < 0.01 vs. 25 µg/mL, n = 6), also indicated a slight difference in cellular metabolic activity between the Z-COTE and fine-ZnO and a significant difference in cellular metabolic activity between the Z-COTE and Z-COTE HP1. At a concentration of 12.5 µg/mL, the bioreduction from Z-COTE treatment was higher than that from fine ZnO (^{^} p < 0.05 vs. fine ZnO). At a concentration of 6.25, 12.5 or 25 µg/mL, the bioreduction from Z-COTE HP1 treatment was higher than that from Z-COTE (^§ p < 0.05 vs. Z-COTE)