Fig. 5. Antibacterial mechanism investigation . (A) Representative CLSM images to assess intracellular ROS generation inK.pneumoniae cells. The samples included normal saline, HMPB(100 μg/mL), Ofloxacin(10 μg/mL), OHH NPs(100 μg/mL) and OHH NPs + NIR (100 μg/mL) (B) The corresponding statistical histogram showing the relative ROS level with Confocal images. (C) ATP level and (D) protein leakage of the K.pneumoniae suspensions treated with different group. (E) Drug resistance development profiles of K.pneumoniae during serial passaging in the presence of sub-MIC dosing of PBS, Ofloxacin, and OHH NPs. The y-axis indicates the folds of increased MIC compared to the initial ones.