*2.5. Bacteria Adhesion*

Gram-positive bacteria (*S. aureus*) and Gram-negative bacteria (*E. coli* and *P. aeruginosa*) were selected to test the antibacterial activity of the films. A single pure colony was cultured in LB medium at 37 ◦C for 18 h. The supernatant was removed by centrifugation and the bacteria were diluted to 10<sup>8</sup> CFU/mL with PBS. The films were immersed in 1 mL bacterial solution and incubated at 37 ◦C with shaking for 24 h. Nonadherent bacteria on the film surface were removed by washing with PBS three times, and then the adherent bacteria were eluted into 1 mL PBS by sonication for 10 min. The amount of bacteria was measured by the flat colony counting method. Additionally, the adherent bacteria on film were studied by confocal laser scanning microscopy (CLSM, NIKON A1R, Tokyo, Japan) after fluorescein diacetate (FDA)/propidium iodide (PI) staining. PI stain selectively binds to the dead bacteria and stains them fluorescent red, whereas the FDA stain selectively binds to the live bacteria and stains them fluorescent green during CLSM imaging.
