Biomedical Application of Hybrid Protein-based Hydrogel

The urgent need for internal bio-adhesives capable of maintaining robust performance in physiological environments has driven the development of novel biomaterials that combine strong wet adhesion, biocompatibility, and mechanical resilience. Such adhesives are essential in diverse clinical contexts, including bone tissue fixation and vascular sealing. However, conventional materials often fall short under physiological conditions due to their limited adhesion strength, long curing times, or insufficient compatibility with biological tissues. This dissertation addresses these limitations by presenting a systematic investigation into the rational design, synthesis, and performance evaluation of recombinant hybrid hydrogels composed of silk, amyloid, and mussel foot protein (SAM) domains. In Aim 1, the sequence–structure–property relationship of SAM hydrogels was elucidated through controlled variation of their β-sheet-forming amyloid components and amorphous mussel foot protein domains. By tuning the ratio of crystalline to amorphous regions, we demonstrate that β-sheet-rich domains significantly enhance cohesive strength, while extended mussel foot protein regions promote interfacial adhesion under wet conditions—key features for successful tissue integration and durability in vivo. In Aim 2, to address the challenge of insufficient mechanical strength, nanocomposite hydrogels were developed by integrating polydopamine-functionalized cellulose nanocrystals (CNCPDA) into the SAM matrix. These rod-like nanoparticles, known for their high stiffness and modifiable surface chemistry, were chosen to improve the hydrogel’s mechanical integrity without compromising flexibility. The catechol functionalities in polydopamine enhanced the interaction between the nanofillers and protein matrix, thereby reinforcing the hydrogel network and expanding its potential use in load-bearing applications such as orthopedic repair. In Aim 3, we focused on optimizing adhesion kinetics and usability under clinically relevant conditions. A composite hydrogel system was formulated by combining SAM proteins with polyacrylic acid (PAA), a biocompatible polyelectrolyte with strong water absorption capacity. The resulting SAM–PAA hydrogels exhibited rapid adhesion to moist biological tissues at low contact pressure (<17 kPa) and short incubation time (<15 minutes), making them promising candidates for vascular repair and other surgical procedures requiring fast, effective sealing with minimal handling. Altogether, this dissertation provides new insights into how molecular-level protein design and nanocomposite strategies that can be leveraged to fine-tune the adhesive and mechanical properties of hydrogels. The results presented here establish a framework for the development of next-generation recombinant protein-based materials tailored for complex biomedical applications. By integrating principles from synthetic biology, protein engineering, and materials science, this research contributes to the advancement of programmable bioadhesives for internal use in regenerative medicine and soft tissue repair.