Fig. 4

a The viability of 7702 and HUVEC cells incubated with CaO₂@Co-Fc with varied concentrations. b Viability of 4T1 tumor cells treated with different concentrations of CaO₂@Co-Fc. c Fluorescence images of calcein-AM and propidium iodide (PI) stained 4T1 cells treated with different concentrations of CaO₂@Co-Fc. d Intracellular H₂O₂ content in 4T1 cells after being treated with CaO₂@Co-Fc. Fluorescence images of (e) ROS level and (f) Ca²⁺ ions in 4T1 cells with different treatments. g The expression of PMCA4, TRPA1, BAX, BCl-2 and caspace-3 in 4T1 cells after treated with CaO₂@Co-Fc. h Schematic illustration for the intracellular functioning mechanism of CaO₂@Co-Fc