Photothermal-Immunomodulatory Nanohydrogel Eradicates Infection and Accelerates Bone Regeneration in Infected Defects

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Nanotechnology

Background:

• Infected bone defects present significant clinical challenges due to persistent infection and poor bone regeneration.
• Existing treatments often struggle to simultaneously address bacterial infection and promote osteogenesis.

Purpose of the Study:

• To develop a multifunctional nanocomposite hydrogel for treating infected bone defects.
• To investigate the combined antibacterial and osteogenic potential of the hydrogel system.

Main Methods:

• Fabrication of a nanocomposite hydrogel (PNPs@RuO2@HAP@Gel) integrating photothermal/antioxidant-responsive polymer nanoparticles (PNPs@RuO2) and nano-hydroxyapatite (HAP).
• Evaluation of photothermal antibacterial efficacy using near-infrared (NIR-II) laser irradiation.
• Assessment of antioxidant properties and biocompatibility as a bioactive scaffold.
• In vivo testing in a rat model of infected bone defects to evaluate antimicrobial activity, immune modulation, and bone regeneration.

Main Results:

• The hydrogel demonstrated potent photothermal antibacterial activity against bacterial membranes and metabolic functions upon NIR-II laser exposure.
• Ruthenium oxide (RuO2) effectively scavenged reactive oxygen species, modulating the immune microenvironment.
• The hydrogel scaffold promoted osteoblast adhesion, growth, osteogenic differentiation, and new bone and blood vessel formation in vivo.
• The system significantly reduced pro-inflammatory cytokines in the infected bone defect model.

Conclusions:

• The multifunctional nanocomposite hydrogel offers a dual-action therapeutic strategy for infected bone defects.
• It effectively eliminates bacteria via photothermal therapy and supports bone regeneration through its bioactive scaffold properties.
• This innovative material presents a promising approach for enhanced treatment outcomes in challenging bone defect scenarios.