Antibacterial effect of singlet oxygen depending on bacteria surface charge

• Bactericidal activity of superoxide anion and singlet oxygen was investigated. • Photofunctional polymer films were used to generate these reactive oxygen species. • The activity of singlet oxygen was independent of the bacterial surface charge. • The activity of superoxide anion was lower for negative bacterial surface charges. Here, we investigated the bactericidal effects of two types of photoinduced reactive oxygen species (ROS), superoxide anion and singlet oxygen, on bacteria with distinct surface charges. We fabricated photofunctional polymer films (PFPFs) capable of generating both types of ROS, and they were subjected to photodynamic inactivation tests for 12 various strains of Acinetobacter baumannii . The results showed that the type I ROS (superoxide anion) was significantly dependent on the surface charge of the bacteria owing to charge-charge repulsion, while the type II ROS (singlet oxygen) was independent of the surface charge of the bacteria. These results could be significant in enhancing treatment efficiency in the clinical field.