Bioinspired Mineral-Organic Bone Adhesives for Stable Fracture Fixation and Accelerated Bone Regeneration

The use of hydrogel-based bone adhesives has the potential to revolutionize the clinical treatment of bone repairs. However, severe deficiencies remain in current products, including cytotoxicity concerns, inappropriate mechanical strength, and poor fixation performance in wet biological environments. Inspired by the unique roles of glue molecules in the robust mechanical strength and fracture resistance of bone, a design strategy is proposed using novel mineral-organic bone adhesives for strong water-resistant fixation and guided bone tissue regeneration. The system leveraged tannic acid (TA) as a phenolic glue molecule to spontaneously co-assemble with silk fibroin (SF) and hydroxyapatite (HA) in order to fabricate the inorganic-organic hybrid hydrogel (named SF@TA@HA). The combination of the strong affinity between SF and TA along with sacrificial coordination bonds between TA and HA significantly improves the toughness and adhesion strength of the hydrogel by increasing the amount of energy dissipation at the nanoscale. This in turn facilitated adequate and stable fixation of bone fracture in wet biological environments. Furthermore, SF@TA@HA promotes the regeneration of bone defects at an early stage in vivo. This work presents a type of bioinspired bone adhesive that is able to provide stable fracture fixation and accelerated bone regeneration during the bone remodeling process.