Light-activated antibacterial surfaces comprise photosensitizers

Antibacterial surfaces were prepared using a base polyethylene sheet topped with a layer containing a mixed powder of poly (vinylidene fluoride) and photosensitizers (PSs). A crimpled stamp was placed on the mixed powder, and then it was passed through a heating and pressing device. The three chosen PSs were rose bengal, toluidine blue O and methylene blue. Scanning electron microscope analysis showed that the PS surface texture was coarse and highly developed. Measurement of the apparent contact angles of the droplets deposited on the PS surfaces using goniometry showed that all three surfaces were hydrophobic. Photodynamic analysis of the surfaces into which the PSs were incorporated indicated significant reactive oxygen species formation after illumination with light fluency rate of 1.46 mW cm ^-2 for 30 min. Photodynamic inactivation assays performed in nutrient broth demonstrated more than 4 log reduction of the attached Escherichia coli after illumination (1.46 mW cm ^-2) for 24 h when the inoculum was 10 ³ CFU mL ^-1. However, more than 4 log reduction of Staphylococcus aureus occurred even when the cultures were illuminated for only 6 h. Our results provide an inexpensive, simple, state-of-the-art method for preparing antibacterial surfaces that may help prevent infections in hospital surroundings and in some medical devices. Antibacterial surfaces were prepared using a base polyethylene sheet topped with a layer composed of a mixed powder of polyvilydene fluoride and photosensitizers. Photodynamic inactivation assays using the surface, including rose bengal (RBPVDF), toluidine blue O (TBOPVDF) and methylene blue (MBPVDF), demonstrated about 4 log reduction of the attached Escherichia coli after illumination (1.46 mW cm ^-2) for 24 h, while for Staphylococcus aureus it occurred after only 6 h. Bacterial cells attached to the PS surfaces, E. coli (A) and S. aureus (B), with illumination for 3, 6 and 24 h (white bars) and without illumination (black bars).