Chemistry Seminar: Dynamic Covalent Hydrogels for Cellular Applications
Abstract: Dynamic hydrogel platforms have recently emerged as a subject of intense interest with applications in bioprinting, injectable cell delivery vehicles, and viscoelastic tissue mimics or scaffolds. Dynamic covalent chemistries in particular present an opportunity to carefully control the rate of bond exchange kinetics, enabling decoupled control over material properties such as elastic modulus or stress relaxation lifetime. Within this context, we developed a poly(ethylene glycol) (PEG) hydrogel platform using a reversible thia-conjugate addition crosslinker. By controlling the aromatic substituents on the conjugate acceptor, we demonstrate that we can preferentially control the forward reaction kinetics, which alters the overall modulus of the hydrogel with minimal effect on the stress relaxation properties. Conversely, the stress relaxation properties are highly sensitive to pH. These properties lend multiple handles with which to tune the ease of injectability of these hydrogels through clinically-relevant syringes. Finally, we examined the cytocompatibility of our hydrogels with live mammalian cells, indicating promise for biomedical applications. Overall, this work suggests a strategy to decouple bulk hydrogel parameters using tunable bond exchange kinetics.