Fig. 2.

In vitro antibacterial activities against MRSA and the antimicrobial mechanisms. (A) Schematic illustration of antibacterial test by agar plate counting method. (B–D) Quantitative bacterial viability by lg (CFU/mL) after various treatments with or without NIR laser irradiation for 10 min (808 nm, 1.0 W/cm²). Data are presented as mean ± SD (n = 3), and # represented that no colonies were observed. (E) CLSM images of Live/Dead bacteria staining assay (scale bar: 30 μm). The concentrations of PL and ICG were all 20 μg/mL. (F) Biological SEM images of MRSA after different treatments. The arrows signified the morphological damage (scale bar: 500 nm). (G) Quantified bacterial ATP activity relative to the control (n = 3). (H) Relative intracellular protein leakage from treated MRSA (n = 3). (I) The absorbance at 260 nm of released nucleic acids from MRSA (n = 3). Note: ns signified no significant difference vs control, ∗∗p < 0.01 vs control, ∗∗∗∗p < 0.0001 vs control. The concentrations of PL and ICG in (F-I) were all 30 μg/mL.