Oxyhemoglobin-Based Nanophotosensitizer for Specific and Synergistic Photothermal and Photodynamic Therapies against Oral Infection

Photothermal therapy (PTT) and photodynamic therapy (PDT) are emerging alternative antibacterial approaches. However, due to the lack of selectivity of photosensitizers for pathogenic bacteria, these methods often show more or less different degrees of in vivo toxicity. Moreover, it is difficult for PDT to exert effective antibacterial effects against anaerobic infections due to the oxygen deficiency. As one of the major anaerobic pathogens in oral infections, Porphyromonas gingivalis (P. gingivalis) acquires iron and porphyrin mainly from hemoglobin in the host. Hence, we developed a nanophotosensitizer named as oxyHb@ IR820 through stable complexation between oxyhemoglobin and IR820, which is a photosensitizer possessing both PTT and PDT performance, for fighting P. gingivalis oral infection specifically and efficiently. Owing to hydrophobic interaction, oxyHb@IR820 had much stronger photoabsorption at 808 nm than free IR820, and thus exhibited significantly enhanced photothermal conversion efficiency. As an oxygen donor, oxyHb played an important role in enhancing the photodynamic efficiency of oxyHb@IR820. More importantly, oxyHb@IR820 showed efficient and specific uptake in P. gingivalis and exerted synergistic PTT/PDT performance against P. gingivalis and oral infection in golden hamsters. In summary, this study provides an efficient strategy for delivering photosensitizers specifically to P. gingivalis and augmenting antibacterial PDT against anaerobic infections.