Wet Adhesion Characterization of Hydrogel Sealants

Hydrogels – crosslinked polymer networks – are attractive candidates for medical applications such as wound dressing. Gelatin methacryloyl (GelMA) is a model biopolymer employed as a bioadhesive due to its similarity to native extracellular matrices, and it can be covalently crosslinked upon exposure to ultraviolet light, which results in robust mechanical stiffness. However, GelMA has weak mechanical strength before crosslinking, leading to undesired flows and dilution. We propose to overcome the low mechanical strength of GelMA by incorporating oppositely charged block polyelectrolytes (bPE) that self-assemble ionically when mixed, resulting in higher mechanical robustness prior to photocuring. To quantify the adhesive properties of the system, a burst pressure apparatus used to measure the maximum pressure that the hydrogel can sustain. We employ versatile testing in dry and underwater environments to study the adhesion in physiological conditions. The incorporation of bPE prevents dilution and enables wet adhesives that can withstand burst pressures up to 8 kPa. This work combines the fabrication of model interpenetrating polymer networks and bioadhesion testing protocol, which provides a model study for other polymers relevant in wet adhesion.