Fig. 5

A Intracellular ROS level indicated by DCFH-DA fluorescence staining after diverse treatments. B Scheme of the ROS overproduction induced by the Cu ions mediated Fenton-like reaction and the visible light mediated photocatalytic process. C SEM micrographs of E. coli and MRSA after different treatments. D Scheme of the interaction of the physical contact, ROS generation and photothermal effects, which collaboratively led to the damage of bacteria cell membrane. Group I: control group in the absence of NFs; Group II: NIR group with the irradiation of NIR laser (808 nm, 1.5 W cm⁻², 10 min) in the absence of NFs; Group III: Cu₃SnS₄ group with the treatment with Cu₃SnS₄ NFs under no laser irradiation; Group IV: Cu₃SnS₄ + NIR group with the treatment with Cu₃SnS₄ NFs plus NIR irradiation (808 nm, 1.5 W cm⁻², 10 min). All groups were exposed to visible light for 20 min