Figure 3

Figure 3

Effects of ZnO-NPs on the production of reactive oxygen species (ROS) and superoxide in human GSCC cells. (a,b) Ca9-22 cells were incubated with ZnO-NPs for short-term (30–60 min) and long-term (24 h) treatments. Then, the production of ROS and superoxide was examined by ROS/superoxide detection kit. H₂O₂ was used as a positive control. (c) Ca9-22 cells were treated with ZnO-NPs for the indicated times to determine the intracellular ROS by flow cytometry analysis. Representative flow cytometry-based ROS patterns are shown. The quantification of ROS intensity was analyzed using CellQuest software. (d,e) Ca9-22 and OECM-1 cells were treated with the indicated concentrations of ZnO-NPs with or without N-acetyl-L-cysteine (NAC) (5 mM) for 24 h. Then, the cell viability was determined using MTT assay. Data are expressed as mean ± SEM of four independent experiments. * p < 0.05 compared with control group; # p < 0.05 compared with ZnO-NP-treated group.