Enzyme-Modified DOPA-Containing Silk Fibroin Bioadhesives with Dynamic Cross-Linking Properties

Silk fibroin (SF) hydrogels face long-standing challenges in simultaneously achieving rapid gelation, robust mechanical performance, dynamic self-healing, and universal adhesion for epidermal bioelectronics. These limitations stem from inefficient cross-linking strategies and the lack of active adhesive motifs. To address this, we developed an enzymatic dynamic cross-linking strategy to fabricate high-performance, all-silk bioadhesives. By engineering tyrosinase (TYR) selection, we identified a bacterial enzyme that outperforms its commercial counterpart, achieving a 6.8-fold higher DOPA conversion yield (2.7 mol%) in SF, attributed to its optimal size and favorable electrostatics. The incorporated DOPA residues enabled rapid, pH-triggered Fe³⁺ coordination, forming hydrogels with tunable mechanical properties (modulus: 3-13 kPa, strain >250%), high adhesion strength (18-40 kPa across diverse substrates), and excellent self-healing capabilities. The developed hydrogel also demonstrated biocompatibility and stable adhesion, as validated by in vitro cytocompatibility assays and successful integration as a conformal interface in a wearable microfluidic sweat sensor for real-time, multi-ion monitoring during exercise. This work establishes a generalizable strategy for designing pure protein-based dynamic hydrogels tailored for advanced biointerfaces.