Adaptable to Mechanically Stable Hydrogels Based on the Dynamic Covalent Cross-Linking of Thiol-Aldehyde Addition.

We exploit the thiol-aldehyde addition (TAA) reaction to build a dynamic covalent cross-linking (DCC) hydrogel in the physiological-pH environment. Due to the rapid and reversible TAA reaction, the resulting hydrogels are readily adapted for convenient manipulation, for example, free molding, easy injection, and self-healing. Meanwhile, the labile hemithioacetal bonds within the DCC hydrogel can convert to thermodynamically stable bonds via spontaneous thiol transfer reactions, thereby realizing poststabilization as needed. The successful application as a long-term scaffold for repair of barely self-healed bone defect indicated the hydrogels with both adaptability and mechanical stability based on thiol-aldehyde addition reaction is significant for biomedical areas.