Injectable composite hydrogels based on minocycline and NIR photothermal therapy for antimicrobial and bone regeneration.

Periodontitis is a chronic infectious disease caused by plaque microorganisms, leading to the destruction of collagen fibers and alveolar bone absorption. Advanced stages of periodontitis require surgical intervention to regenerate periodontal tissues. Traditional guided tissue regeneration (GTR) membranes have limitations in promoting tissue regeneration, primarily due to insufficient antibacterial properties and inability to conform to various bone defect shapes. This study introduces an injectable hydrogel (MH-TTB@CSA) combining carboxymethyl chitosan, sodium alginate, minocycline, and TTB nanoparticles, enhanced by near-infrared (NIR) photothermal therapy. The hydrogel offers precise defect matching and exhibits strong antibacterial effects under 808 nm irradiation (50 °C). Additionally, minocycline's properties and NIR-induced mild photothermal treatment (40 °C) stimulate bone growth by upregulating alkaline phosphatase (ALP) and promoting mineralization. By adjusting TTB nanoparticle concentration and laser power, the hydrogel effectively switches between antibacterial and osteogenic modes. This creates an optimal microenvironment for bone regeneration, making it a promising approach for treating bone defects.