Construction of D-A-Conjugated Covalent Organic Frameworks with Enhanced Photodynamic, Photothermal, and Nanozymatic Activities for Efficient Bacterial Inhibition

Bacterial infection causes serious threats to human life, especially with the appearance of antibiotic-resistant bacteria. Phototherapeutic approaches have become promising due to their noninvasiveness, few adverse effects, and high efficiency. Herein, a covalent organic framework (TAPP-BDP) with a conjugated donor-acceptor (D-A) structure has been constructed for efficient photoinduced bacteriostasis. Under the irradiation with a single near-infrared (NIR) light (lambda = 808 nm), TAPP-BDP alone involves triple and synergistic bacterial inhibition based on the integration of photodynamic, photothermal, and peroxidase-like enzymatic activities. The unique D-A structure endows TAPP-BDP with a narrow energy band gap, improving its photodynamic and nanozyme activities to generate reactive oxygen species (ROS) to realize the broad-spectrum bactericidal activity. The extended pi-conjugated skeleton of TAPP-BDP results in enhanced absorption in NIR, and the remarkable photothermal activity can increase the temperature up to 65 degrees C to cause efficient bacterial degeneration. TAPP-BDP shows excellent antibacterial efficiency against both Gram-negative and Gram-positive bacteria. Animal experiments further suggest that TAPP-BDP can effectively heal wounds infected with Staphylococcus aureus in living systems.