Near Infrared Responsive Injectable Hydrogel with Bioactive Glass and Copper Nanostructures for Photothermal Antibacterial and Periodontitis Treatment

The treatment of periodontitis remains challenging because it requires both infection control and tissue repair. In this study, a multifunctional injectable hydrogel is based on oxidized sodium alginate (Alg‐OX) and gelatin, incorporating copper–tannic acid (CuT) and bioactive glass (BG), with the intention of synergistically addressing infection control and treating periodontal defects are designed. The hydrogel demonstrate inherent antibacterial activity, while the presence of BG has the potential to release osteoconductive ions, promoting tissue mineralization. Upon near‐infrared (NIR) irradiation, the hydrogel exhibited photothermal conversion, thereby demonstrating an antibacterial effect against Aggregatibacter actinomycetemcomitans through localized mild hyperthermia. The hydrogels also exhibit an antibacterial effect against Gram‐positive bacteria, although this effect was less robust against them. Selectively targeting Gram‐negative species minimizes disruption to beneficial Gram‐positive commensals, preserving the oral microbial balance and reducing the risk of secondary dysbiosis. Additionally, the hydrogel demonstrates favorable injectability, biocompatibility, and the ability to support cell viability and migration. These integrated functions enable the hydrogel to effectively suppress bacterial colonization and accelerate periodontal tissue regeneration. Altogether, this composite hydrogel represents has the potential to be used for treating periodontitis, offering biocompatibility, antibacterial, and potential regenerative characteristics.