Oxygen‐Free Polycationic Photosensitizers for Treatment of Periodontal Inflammation

Abstract Periodontal tissue infection is a chronic destructive inflammatory disease caused by bacteria including anaerobes and facultative anaerobes. Traditional mechanical debridement and antibiotic treatments are not effective at removing biofilm from the root surface, resulting in recurrent disease. Antimicrobial photodynamic therapy (aPDT) is a promising bactericidal method, but it is limited by oxygen content. Here, an oxygen‐free cationic polymer (HQRB‐SS‐Dex) containing the photosensitizer rose bengal (RB) and dextran is proposed. It releases both 1 O 2 and HO•, and it exhibits strong antibacterial efficiency against periodontal pathogenic bacteria under irradiation. The positively charged quaternary ammonium polymer and dextran of HQRB‐SS‐Dex facilitate adherence to the bacterial surface and penetration of the bacterial biofilm to permit efficient use of reactive oxygen species. Disulfide bonds make the complex biodegradable, which improves biosafety. This work presents a unique branched cationic polymer for oxygen‐free aPDT, with potential application to the treatment of periodontal infection.