Figure 17.

ROS measurement of bacterial strains treated with TiO₂ nanoparticles. (A) S. typhimurium and (B) E. coli treated for 0 and 4 h at low (50 μg/mL) and high (250 μg/mL) concentrations, as determined by flow cytometry. Fluorescent intensity of cells shifted toward left at immediate exposure, that is, 0 h as well as at 4 h exposure in accordance with the milling time. (a,b) represent the DCF fluorescent intensity and fold change DCF signal intensity of exposed bacterial cells at 50 μg/mL; (c,d) present the DCF fluorescent intensity and fold change DCF signal intensity of exposed bacterial cells at 250 μg/mL. DCF fold change was calculated with respect to cells with no exposure (control); the cells were stained with the DCFHDA dye to measure ROS, which fluoresce green when reacting with ROS. The value represents mean ± SD of three independent experiments. *P < 0.05 denotes the significant change from bulk particles and number of * represents the extent of significance.