Preparation of adhesive and degradable hydrogels with adjustable viscosity by photo controlled RAFT polymerization

Injectable photo-crosslinkable adhesive hydrogels represent an effective strategy for achieving in vivo wound hemostasis and promoting healing. However, developing adhesive gel dressings that simultaneously possess strong tissue adhesion, injectability, photo-curability, inherent antimicrobial properties, and excellent biocompatibility remains a significant challenge. Herein, by employing photo-controlled reversible addition–fragmentation chain transfer (RAFT) polymerization, in which the polymerization process can be “turned on” and “suspend” by regulating the light source, a spatiotemporally controllable hydrogel was prepared using the photo-RAFT agent (InZ), acrylic acid (AA), and acryloyl chitosan (AeCS).Benefiting from the properties of photoinitiator InZ, the photopolymerization process can be precisely regulated under ambient conditions, allowing for in situ gel formation directly at wound sites. The obtained hydrogel exhibited excellent mechanical properties, swelling behavior, and biocompatibility (>80%). It showed strong adhesion (>11.8kpa) and repeatable adhesiveness to skin tissue and also adhered well to various substrates. Moreover, it displayed good inherent antimicrobial capability against Escherichia coli (73.4%∼89.96%) and Staphylococcus aureus (72.7%∼87.04%). By introducing a natural macromolecular crosslinker, the hydrogel was endowed with degradability. Notably, based on the characteristics of photo-controlled RAFT polymerization, a prepolymer solution with tunable viscosity was obtained, endowing the hydrogel with injectability. Taken together, these results indicate that the constructed hydrogel holds great potential as a biomedical material.