An Ultrasmall Strontium‐Loaded Polydopamine Nanoformulation for Near‐Infrared‐Enhanced Periodontitis Therapy via Photodynamic Gas‐Promoted Antibacterial and Bone Repair

ABSTRACT Periodontitis is a chronic infectious oral disease triggered by periodontopathogenic bacteria, resulting in the progressive inflammation and destruction of the tissues surrounding teeth. To achieve reprogramming of the infectious microenvironment for periodontitis therapy, a nanoformulation was proposed by loading polydopamine (PDA) with ultrasmall strontium through in situ reduction and arginine by Michael addition, defined as PA. Combined with near infrared (NIR) irradiation, it could efficiently scavenge reactive oxygen species (ROS), and downregulate inflammatory factors expression through inhibiting NF‐κB pathway. In addition, it also confirmed the effective bacteria killing in NIR stimulated PA by photothermal effects and nitric oxide (NO) generation. Significantly, PA + NIR was also verified to promote alveolar bone tissue repair through strontium ions (Sr 2+ ) and NO induced angiogenesis, together with Sr 2+ mediated osteogenesis. The administration strategy was finally verified to alleviate the oxidative stress derived inflammation, suppress bacterial growth and biofilm formation, as well as promote bone regeneration with high efficacy and biosafety in the periodontitis rat models. All the above findings contributed to the NIR enhanced synergistic treatment of periodontitis, and it may serve as a promising strategy for the treatment of other inflammation related diseases.