A pH-sensitive CuHP composite hydrogel featuring antibacterial, antioxidant and osteogenic properties for treating diabetic periodontitis

Periodontitis, a chronic inflammatory disorder primarily induced by bacterial infection and exacerbated by excessive oxidative stress, leads to the destruction of alveolar bone. Diabetes mellitus intensifies this oxidative stress in periodontal tissues and disrupts the oral microbiome, thereby aggravating periodontal conditions and complicating the management of periodontitis. The development of materials that possess comprehensive therapeutic effects, including antibacterial, antioxidant and osteogenic properties, for the treatment of diabetic periodontitis (DP) remains at the forefront of research. In this study, we introduced a copper hydrogen phosphate (CuHP) composite hydrogel, which exhibited multi-enzymatic activities at varying pH levels. This hydrogel was synthesized by encapsulating CuHP within a commercially available sodium alginate (SA) matrix. <i>In vitro</i> analyses explored the pH-responsive enzymatic activities, biocompatibility and the antioxidant, osteogenic and antibacterial properties of the resultant SA/CuHP composite hydrogel. At neutral pH, the hydrogel primarily exhibited catalase-like activity, providing it with antioxidant capabilities that reduced the inhibitory effects of oxidative stress on osteogenesis in bone marrow mesenchymal stem cells. In mildly acidic conditions, the hydrogel displayed peroxidase-like activity, catalysing the production of more potent reactive oxygen species and exhibiting significant antibacterial efficacy against <i>Aggregatibacter actinomycetemcomitans</i>. Furthermore, the SA/CuHP hydrogel continuously released copper ions, which synergistically enhance its osteogenic and antimicrobial efficacies. <i>In vivo</i> studies demonstrated that this composite hydrogel significantly inhibited bacterial growth and promoted bone regeneration in a rat model of DP. These findings suggest that the SA/CuHP hydrogel holds substantial potential for the treatment of periodontitis in patients with diabetes.