Chemically Triggered Hydrogel Transformations through Covalent Adaptable Networks and Applications in Cell Culture.

In this article, we report a "smart" hydrogel system, which can be remodeled into multiple architectures through dynamic covalent adaptable networks. The topological changes in hydrogel structures yield dynamically tunable properties through the reformation of covalent chemical linkages via amine-thiol scrambling, thiol-thiol exchange, decoupling reaction, and disulfide formation. The stiffness of the hydrogels can be regulated via dynamic covalent bonding, with some hydrogels displaying self-healing and shear thinning properties, as demonstrated by rheological measurements. Significantly, the dramatic structural transformations are achieved under neutral aqueous conditions at room temperature. These "smart" hydrogels show good biocompatibility, which can induce cell growth in two-dimensional cell culture and effectively serve as a scaffold for encapsulating and releasing human mesenchymal stem cells in three-dimensional cell culture. Thus, the developed "smart" hydrogel system holds great potential in biomedical applications such as tissue engineering and cell therapy.