Dynamic Protein-Metal Ion Networks: A Unique Approach to Injectable and Self-Healable Metal Sulfide/Protein Hybrid Hydrogels with High Photothermal Efficiency

A new strategy is proposed to fabricate adaptable protein-based hydrogel networks with both injectable and self-healable properties. By mixing proteins and metal ions under alkaline conditions, the metal ions can crosslink proteins into protein-metal ion dynamic networks. Subsequently, the metal ions can react with the cysteine residues of protein to in situ form corresponding metal sulfide NPs with ultra-small size, which leads to nanocomposite hydrogels with adaptable structures. This approach is general and a series of metal sulfide NP in situ embedded nanocomposite hydrogels were obtained. As an example, a Bi₂ S₃ -BSA hydrogel with tunable networks is shown to serve as an injectable, self-healable photothermal agent for the treatment of tumors. Our finding paves a new avenue for the preparation of injectable and self-healable hydrogels with potential applications in biomedicine.