Hybrid Hydrogels with Orthogonal Transient Cross-linking Exhibiting Highly Tunable Mechanical Properties

Compositional changes in the chemical makeup of hydrogels offer a powerful strategy for fine tuning of mechanical properties, enabling specific targeting for different applications. The chemical versatility exhibited by the tunable system introduced here can be leveraged to address a broad range of characteristics across the field of tissue engineering-from blood vessels to cartilage, for example-which demands materials with very different mechanical profiles. Furthermore, we rely exclusively on dynamic, non-covalent cross-linking to provide opportunities for 3D printing and injectability. This work describes a highly tunable system based on hydrogen bonding and ionic interactions. Single network hydrogels were made by exploiting various acrylic monomers including N-acryloyl glycinamide (NAGA) and acrylic acid (AAc). Additionally, hybrid hydrogels were explored by combining these acrylic networks with an ionically cross-linked alginate network. By combining orthogonal cross-linking strategies and altering the ratio between different components in these hybrid gels, a broad range of mechanical properties is demonstrated. The characteristics were extensively investigated using tensile testing, compression testing, and rheological measurements. The final scaffolds were also shown to be non-cytotoxic in preliminary cell viability studies for human dermal fibroblasts.