Figure 2.

Evaluation of NO diffusing capacity in MCTS model. a) Schematic illustration of NIR‐stimuli NO release from BNN‐Bi₂S₃ in 3D tumor spheroid model. b) The bright field and dark field images of the frozen sections of tumor spheroids with or without BNN‐Bi₂S₃ treatment. Arrows represent dark‐field signal of BNN‐Bi₂S₃ nanoparticles. The scale bars are 100 µm. c) Confocal images of tumor spheroid with different treatments. The cells were stained with Hoechst 33342 (blue) and DAF‐FM (green). The concentration of BNN‐Bi₂S₃ nanoparticles is 20 µg mL⁻¹. The irradiation power is 0.5 W cm⁻², for 10 min. d) Flow cytometry analysis of BEL‐7402 cells trypsinized from the tumor spheroids in different groups. The shadow curve is the unstained negative control.