Fig. 4

In vitro biocompatibility and antioxidant effect of hydrogels and PB nanozymes. (A) NIH-3T3 cells were stained with calcein-AM (green) and propidium iodide (PI, red) after different treatments for 24 h. Bars represent 75 μm. (B) Cell viability of NIH-3T3 cells evaluated by the MTT assay after different treatments for 24 h. (C) ROS fluorescence images of NIH-3T3 cells after different treatments. Bars represent 75 μm. D) Cell viability of NIH-3T3 cells evaluated by the MTT assay after different treatments. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. RL (red light) indicates 730 nm red light irradiation. Data are presented as the means ± SDs (n = 3)