Water-soluble PANI:PSS designed for spontaneous non-disruptive membrane penetration and direct intracellular photothermal damage on bacteria

The major challenge in the field of antibacterial agents is to overcome the low-permeability of bacteria cell membranes that protects the cells against diverse drugs. In this work, water-soluble polyaniline (PANI)-poly (p-styrenesulfonic acid) (PSS) (PANI:PSS) is found to spontaneously penetrate bacteria cellular membranes in a non-disruptive way, leaving no evidence of membrane poration/disturbance or cell death, thus avoiding side effects caused by cationic ammonia groups in traditional ammonia-containing antibacterial agents. For aqueous synthesis, which is important for biocompatibility, the polymer is synthesized via an enzyme-mimetic route relying on the catalysis of a nanozyme. Owing to its fluorescent properties, the localization of as-prepared PANI:PSS is determined by the confocal microscope, and the results confirm its rapid entry into bacteria. Under 808 nm near-infrared (NIR) irradiation, the internalized PANI:PSS generates local hyperthermia and destroys bacteria highly efficiently from inside the cells due to its excellent photothermal effects. Staphylococcus aureus (S. aureus), Methicillin-resistantStaphylococcus aureus (MRSA) and Escherichia coli (E. coli) could be effectively eliminated as well as the corresponding bacterial biofilms. Results of in vivo antibacterial experiments demonstrate excellent antibacterial activities of the water-soluble PANI:PSS without side effects. Therefore, the prepared water-soluble polymer in this study has great potential in the treatment of various bacterial infections.