A shape-adaptive hydrogel with dual antibacterial and osteogenic properties for alveolar bone defect repair

Alveolar bone defects are often irregular in shape and can severely affect patients' physical and psychological well-being, posing significant challenges in treatment, particularly in cases complicated by systemic diseases. This study presents a shape-adaptive hydrogel with sequential antibacterial and osteogenic functions designed to repair irregular bone defects associated with osteoporosis. Naringin, an estrogen analogue, was conjugated to the hydrogel via disulfide bonds and then uniformly mixed with nano-hydroxyapatite (nano-HAP) to create microspheres. These microspheres were uniformly dispersed within the naringin-loaded hydrogel, forming an injectable and photocurable suspension. Upon implantation, naringin is rapidly released due to diffusion along the concentration gradient and initial hydrogel degradation, providing antibacterial effects and preventing infection. As bone repair progresses, the hydrogel undergoes further degradation and the disulfide bonds break, so that naringin is continuously released, which enhances osteoblast differentiation and inhibits osteoclast differentiation. Material characterization confirmed the presence of disulfide bonds and the sustained release profile of naringin. Both in vitro and in vivo experiments demonstrated the hydrogel's excellent biocompatibility and its effectiveness in repairing regular mandibular defects as well as irregular alveolar bone defects associated with osteoporosis. This hydrogel provides a promising strategy for the development of advanced biomaterials tailored to the complex requirements of irregular bone defect repair under osteoporotic conditions.