Fig. 3

 A UV-vis-NIR absorption spectra of MB aqueous solutions containing H₂O₂ and Au@Cu_2−xSe NPs after treatments at different temperatures. The inset photograph shows the corresponding color changes of MB solutions. Au@Cu_2−xSe: 100 µg mL⁻¹. MB: 10 µg mL⁻¹. H₂O₂: 10 mM. B ESR spectra of Au@Cu_2−xSe NPs recorded at different temperatures. The spin trap was DMPO. Au@Cu_2−xSe: 50 µg mL⁻¹. DMPO: 50 mM. H₂O₂: 100 µM. C CLSM images of 4T1 tumor cells after different treatments, where Hoechst 33,342 (blue) and OH580 (red) were used to observe the cell nucleus and ·OH generation, respectively. Scale bar = 50 μm. Au@Cu_2−xSe: 50 µg mL⁻¹. H₂O₂: 100 µM. NIR: 808 nm laser, 1.0 W cm⁻² for 5 min