Nanoparticle-mediated photothermal and photodynamic antibacterial therapy for the treatment of periodontitis

Periodontitis is a bacteria-induced infectious disease that can lead to tooth loss and contribute to various systemic conditions. Current nonsurgical therapies, such as mechanical debridement with antibiotics administration, face significant challenges, including limited access to bacteria hard-to-reach areas and the risk of antibiotic resistance. To address these issues, we developed Zinc Phthalocyanine-loaded Mesoporous Polydopamine (ZnPc-MPDA) nanoparticles, which demonstrate excellent photothermal (PTT) and photodynamic (PDT) properties. ZnPc-MPDA nanoparticles penetrate deep into periodontal lesions, effectively eliminating dental biofilms and killing bacteria under light irradiation without inducing antibiotic resistance. In vitro , ZnPc-MPDA showed good biocompatibility with fibroblasts at an optimal concentration of 100 μg/mL. Antibacterial rates against periodontitis-associated bacteria Fusobacterium nucleatum ( F. nucleatum ) and Streptococcus gordonii ( S. gordonii ) were 99.96 % and 99.94 %, respectively, under successive irradiation with 808 nm and 635 nm lasers. Additionally, biofilm survival rates of F. nucleatum and S. gordonii after ZnPc-MPDA treated were 17.5 % and 13.7 %, respectively. The superior antibacterial efficacy of ZnPc-MPDA can be attributed to the synergistic effects of PTT and PDT. In a rat periodontitis model, ZnPc-MPDA demonstrated light-activated, safe, and efficient antibacterial activity with mild photothermal effects, reducing alveolar bone resorption, inflammation, and collagen degradation. Overall, this study presents a promising photothermal/photodynamic synergistic strategy for the treatment of periodontitis.