Dynamic regulable sodium alginate/poly(γ-glutamic acid) hybrid hydrogels promoted chondrogenic differentiation of stem cells.

Traditional hydrogels often fail to match the dynamic interactions between mechanical and cellular behaviors exhibited by the natural cartilage extracellular matrix. In this research, we constructed a novel hybrid hydrogels system based on sodium alginate and polyglutamic acid. By controlling the grafting rate and concentration of polymer, the gelation time and mechanical strength can be adjusted between range of 8-28 s and 60-144 kPa. By adding microcrystalline cellulose into the system, so that the degradation time was prolonged (125%) and the swelling rate was reduced (470%). Additionally, the presence of hydrazone bonds gives the system some dynamic response characteristics, and the hydrogel exhibits excellent self healing and injectable ability. It was found that the system had positive cytocompatibility (80%), which accelerated regulatory gene expression in cartilage tissue. In conclusion, this injectable hydrogel with self-healing and customizable mechanical strength will have broad application prospects in future biomedical engineering.