Hydrogels Stabilized Via Novel Click Chemistry-Enabled Secondary Interactions for Cell Culture

Hydrogels, water-imbibing crosslinked polymer networks, are useful for 3D cell culture because of their tissue-like mechanical properties and high water content. A variety of “click chemistry” reactions have been utilized to crosslink (covalently bond) the polymer network and incorporate different bio-instructive peptides. Until now, there has been an assumption that the click reaction used does not significantly alter the overall hydrogel properties. However, our lab has found that the tetrazine-norbornene click reaction results in additional non-covalent supramolecular interactions, which increase gel stiffness and decrease enzymatic degradability. Our project aims to leverage these novel non-covalent intermolecular interactions resulting from the Inverse Electron Demand Diels-Alder tetrazine-norbornene click cycloaddition products to develop a user-controlled, dynamically stiffening hydrogel platform that could more accurately recapitulate mechanical characteristics of fibrotic diseases or cancerous conditions in vitro. Although there has been previous research done using thiol-ene reactions to form hydrogel networks and the use of tetrazine-functionalized poly(ethylene glycol) molecules within hydrogels to incorporate bio-instructive materials into the gels, there is limited literature utilizing pendant groups on polymers to control secondary interactions. Therefore, this project aims to explore how different concentrations of pendant tetrazine-norbornene cycloaddition products (TNCPs) influence the mechanical properties of PEG hydrogels