3D-Printable, Self-Stiffening (4D) and Shape Morphing Hydrogel through Single-Step Orthogonal Crosslinking of Phenolic Biopolymers for Dynamic Tissue Engineering.

Particularly for dynamic, shape-changing, or fibrillar tissues such as muscles and blood vessels, the development of innovative biomaterials is crucial for advancing tissue engineering and regenerative medicine. This study introduces a novel multicomponent hydrogel created from silk fibroin (SF), tyramine-modified hyaluronic acid (HA_Tyr), and tyramine-modified gelatin (G_Tyr). Using an enzymatic orthogonal covalent bonding between phenolic groups, i.e., tyrosine and tyramine moieties of SF, HA_Tyr, and G_Tyr, a dynamically stiffening SF/HA_Tyr/G_Tyr (SHG) multicomponent hydrogel is achieved with enhanced mechanical properties. Utilizing an extrusion-based 3D printing approach, the precise fabrication of constructs with tailored geometries and functionalities is demonstrated. The emerging 3D-printed hydrogels undergo morphologic changes (4D) under 37 °C/phosphate buffer saline (PBS) conditions. The observed morphological change results from the conformational change and folding of SF leading to fibrillation. These multicomponent hydrogels also show significant promise in creating bio-instructive materials that meet the mechanical and functional requirements necessary for in situ tissue engineering. The study highlights the potential of these self-stiffening biomaterials to recover dynamic and fibrillar tissues, supported by both in vitro and pre-clinical chorioallantoic membrane (CAM) model evaluations that underscore their biocompatibility and pro-angiogenic properties.