Hydrophilic competent and enhanced wet-bond strength castor oil-based bioadhesive for bone repair

Bone adhesive has been proved to be a promising alternative in the clinical treatment of bone repairs. However, the problems of unsatisfying bone-bonding strength, especially the bonding of cortical bone in vivo, and blocked bone tissue recovery remain barriers to clinical reparation. Benefit from dopamine-modified castor oil synthesized by an epoxy-modification method, a porous and two-component polyurethane adhesive (PUA) was prepared to overcome the current challenges encountered. The tailored surface morphology and open porosity of the adhesive layer can be obtained to meet the requirements of bone repair by tuning the fraction of the formulation. Furthermore, the incorporation of nano-hydroxyapatite improved the mechanical properties and osteocompatibility of the material. Compared with PUA without catechol groups, the introduction of catechol groups not only increased the adhesive strength from 0.28 ± 0.05 MPa to 0.58 ± 0.06 MPa under wet conditions but also enabled the enrichment of Ca²⁺ on the adhesive surface to promote bone regeneration. Besides, the cell culture experiments also indicated that PUAs show good biocompatibility and excellent adhesion to stem cells. Given its excellent wet adhesive strength and biocompatibility, this system demonstrated potential applications in orthopedic treatment.