Stimuli-responsive protein hydrogels: From dynamic tuning of hydrogel mechanics to shape morphing

Protein hydrogels represent a rapidly evolving class of biomaterials with significant potential in biomedicine, soft robotics, and tissue engineering. These hydrogels are uniquely engineered from natural or recombinant proteins, endowing them with biocompatibility, biodegradability, and precise molecular programmability. By integrating dynamic cross-linking mechanisms and responsive moieties, protein hydrogels can be engineered to respond to external stimuli such as temperature, pH, light, or ligands, and undergo reversible or irreversible changes in shape, volume, or mechanical properties. This review critically summarizes recent advances in the design and fabrication of stimuli-responsive protein hydrogels. Emphasis is placed on the molecular design strategies that are used to dynamically tune the mechanical properties and shape-morphing behaviors of protein hydrogels. Challenges and opportunities related to the rational engineering of next-generation stimuli-responsive protein hydrogels are also discussed.