A Novel Z‐Scheme Heterostructured Bi2S3/Cu‐TCPP Nanocomposite with Synergistically Enhanced Therapeutics against Bacterial Biofilm Infections in Periodontitis

Abstract Porphyrin‐based antibacterial photodynamic therapy (aPDT) has found widespread applications in treating periodontitis. However, its clinical use is limited by poor energy absorption, resulting in limited reactive oxygen species (ROS) generation. To overcome this challenge, a novel Z‐scheme heterostructured nanocomposite of Bi2S3/Cu‐TCPP is developed. This nanocomposite exhibits highly efficient light absorption and effective electron–hole separation, thanks to the presence of heterostructures. The enhanced photocatalytic properties of the nanocomposite facilitate effective biofilm removal. Theoretical calculations confirm that the interface of the Bi2S3/Cu‐TCPP nanocomposite readily adsorbs oxygen molecules and hydroxyl radicals, thereby improving ROS production rates. Additionally, the photothermal treatment (PTT) using Bi2S3 nanoparticles promotes the release of Cu2+ ions, enhancing the chemodynamic therapy (CDT) effect and facilitating the eradication of dense biofilms. Furthermore, the released Cu2+ ions deplete glutathione in bacterial cells, weakening their antioxidant defense mechanisms. The synergistic effect of aPDT/PTT/CDT demonstrates potent antibacterial activity against periodontal pathogens, particularly in animal models of periodontitis, resulting in significant therapeutic effects, including inflammation alleviation and bone preservation. Therefore, this design of semiconductor‐sensitized energy transfer represents an important advancement in improving aPDT efficacy and the treatment of periodontal inflammation.