(315d) Double Network Hydrogel Bioadhesives with Tunable Adhesive and Cohesive Properties

Gelatin Methacryoloyl (GelMA) has emerged as a promising material for biomedical applications such as bioadhesives and cell scaffolds for tissue engineering owing to the optimal adhesive strength, biocompatibility, and mechanical properties of its photocrosslinked hydrogels. However, solutions of uncrosslinked GelMA precursors exhibit low viscosity at 37 °C, resulting in material loss and dilution upon extrusion in wet environments prior to photocrosslinking, leading to GelMA deactivation and dilution and limiting its biomedical utility. Overcoming these challenges is an essential step to pave the way for application of GelMA hydrogels as versatile biomaterials in wet environments.

In this study, we introduce a strategy to incorporate polyelectrolyte complex (PEC) networks with GelMA to create double network (DN) hydrogels that overcome the current limitations of dilution and material loss associated with GelMA hydrogels. Mixing of oppositely charged ABA triblock polyelectrolytes and GelMA precursors results in swift formation of the PEC network comprising the oppositely charged polyelectrolytes. Block B consists of neutral polyethylene glycol (PEG), and block A is either guanidinium or sulfonate functionalized poly(allyl glycidyl ether). This self-assembled PEC network hydrogel significantly enhances the mechanical properties of GelMA precursor solution and provides a protective environment that mitigates dilution and material loss in a wet environment. Photocrosslinking of the GelMA precursors in the PEC hydrogels results in DN hydrogels that exhibit improved cohesive properties, such as superior shear moduli, Young’s moduli, toughness, and anti-fatigue characteristics. Our DN hydrogels also exhibit remarkable improvements in adhesion with tissue surfaces as compared to GelMA hydrogels, as characterized through ex vivo burst pressure tests. Both GelMA hydrogels and DN hydrogels have higher adhesion strengths than commercial PEG-based sealant. The superior mechanical properties, biocompatibility, and biodegradability of DN hydrogel make them a promising material platform for development of robust bioadhesives.