Regulation of Crosslinker Concentration on the Degradation Behavior of Pluronic F-127/Carboxymethyl Chitosan/ZnO Hydrogel and Its Evaluation in Vivo and in Vitro

In order to precisely control the degradation rate of injectable thermosensitive hydrogels to match the process of tissue regeneration, Pluronic F-127/carboxymethyl chitosan/ZnO thermosensitive hydrogels with four concentration gradients of 0.5wt.% to 2.0wt.% were prepared using glutaraldehyde as the crosslinking agent. The results showed that the gel time was shortened from 120 s to 60 s, the equilibrium swelling rate was reduced from 55.16% to 23.85%, and the degradation half-life was extended from 4.40 days to 9.31 days with the increase of crosslinking agent concentration. The subcutaneous implantation experiment showed a highly consistent degradation trend both in vivo and in vitro. The antibacterial rate of the hydrogel against Staphylococcus aureus and Escherichia coli was more than 95%, and the cell activity was more than 90%. H&E staining verified good histocompatibility. Mechanism analysis reveals that the concentration of crosslinking agents synergistically determines degradation behavior by regulating three dimensions: the number of crosslinking bonds, molecular diffusion resistance, and segment degradation sensitivity. This study provides a quantitative experimental basis for the customized regulation of the degradation behavior of injectable hydrogels.