Multifunctional injectable protein-based hydrogel for bone regeneration

Abstract Protein plays an important role in the maintenance of osmotic pressure and binding and transportation of nutrients to cells, which is essential for the rapid regeneration of bone tissues. Bovine serum albumin (BSA) is the most abundant plasma protein in the body. Here, theBSA-based hydrogel was first developed through the thiolated bovine serum albumin (sBSA) employing the robust and reversible -SAg coordination, which owns injectable, self-healing and antibacterial properties for the treatment of bone defect regeneration. First, the BSA was treated with Traut's reagent to replace the primary amine groups of the lysine residue in its primary structure with thiol groups. Then, the thiolated BSA (sBSA) was added with silver nitrate to be crosslinked. -SAg coordination took place immediately when sBSA and silver were mixed and a shear-thinning hydrogel was thus produced. By adjusting the proportion of BSA, the mechanical properties of the hydrogels can be adjusted. Moreover, this novel protein-based hydrogel is bio-degradable and can slowly release silver ions to generate an antibacterial effect for P. gingivalis and F. nucleatum bacterial. Moreover, the protein-based injectable hydrogel has very good biocompatibility and bioactivity on promoting bone regeneration. As shown in this study, the in vitro experiments showed that the hydrogel effectively enhanced the osteogenesis differentiation of osteogenic precursor cells. And the in vivo study showed faster and better bone repair outcomes in large cranial defect rabbit model, in comparison to the commercially used spongious bone substitutes (Bio-OSS). Therefore, protein-based hydrogel is a very good promising material for bone regeneration.