Fig. 4

In vitro antibacterial effects of nanomaterials toward laboratory bacteria strains of S. mutans and E. coli. a The growth curve of bacteria after treatment with 200 µg mL⁻¹ nanomaterials for 15 min. b Antibacterial ratios of 200 µg mL⁻¹ nanomaterials against bacteria for 15 min. c Plate photographs of 200 µg mL⁻¹ nanomaterials against bacteria for 15 min. d Live/dead staining images of bacteria after treatment with 200 µg mL⁻¹ nanomaterials under 15 min of irradiation. Scale bars are 20 μm. e SEM images of bacteria after treatment with 200 µg mL⁻¹ nanomaterials under 15 min of irradiation. Scale bars are 1 μm. f TEM images of bacteria after treatment with 200 µg mL⁻¹ nanomaterials under 15 min of irradiation. Scale bars are 300 μm. g, h Photographs of crystal-violet-stained S. mutans biofilms with different treatments and its quantitative analysis. i Live/dead staining images of S. mutans biofilms after treatment with 200 µg mL⁻¹ nanomaterials under 15 min of irradiation. Scale bars are 20 μm. The data are presented as mean ± SD (n = 3). Statistical significance: *P < 0.05; **P < 0.01; ***P < 0.001 and ****P < 0.0001