An injectable and thermosensitive hydrogel with nano-aided NIR-II phototherapeutic and chemical effects for periodontal antibacteria and bone regeneration

Abstract Periodontitis is a common public health problem worldwide and an inflammatory disease caused by periodontal pathogens. Porphyromonas gingivalis ( P. gingivalis ) is the most dominant bacteria in periodontitis and cause irregular defect of periodontal tissue. Both antibacterial therapy and bone regeneration are of great importance in the treatment of periodontitis. In this study, injectable and thermosensitive hydrogels with 3D networks were used as carriers for controlled release of osteo-inductive agent (BMP-2) and Near Infrared Region-II (NIR-II) phototherapy agents (T8IC nano-particles). T8IC nano-particles were prepared by reprecipitation and acted as photosensitizer and crosslinkers of the hydrogel under 808 nm laser irradiation. Besides, we promoted photodynamic therapy (PDT) through adding H 2 O 2 to generate more radical oxygen singlet (ROS) and facilitate the antibacterial effect instead of increasing the temperature of photothermal therapy (PTT). Hydrogel + T8IC + Laser + BMP-2 + H 2 O 2 incorporated with mild PTT (45°C), enhanced PDT and sustained release of BMP-2. It was present with excellent bactericidal effect, osteogenic induction and biosafety in vitro and in vivo . Besides, it was confirmed that PTT and PDT could promote bone regeneration through alleviating inflammation state. Altogether, this novel approach with synergistic antibacterial effect, anti-inflammation and bone regeneration has a great potential for the treatment of periodontitis in the future.