Tuning Elastic and Viscoelastic Mechanical Properties of Double-Network Alginate-Polyacrylamide Hydrogels for Scaffold Design Applications

Due to their soft consistency and unique physiochemical properties, synthetic hydrogel platforms are excellent candidates to construct 2D scaffolds for cell culture. However, the scope of hydrogel applications in tissue engineering is severely limited by poor mechanical properties and the lack of effective energy dissipation mechanisms. To overcome these limitations, double network hydrogels comprised of two interpenetrating gel networks offer remarkable fracture toughness and stretchability, whose properties can be exploited for rational scaffold designs. Here, we systematically study a series of alginate-polyacrylamide (Alg/PAM) double network gels with variable amounts of CaSO4 ionic crosslinker and cell adhesion molecule modifications. Based on both elastic (uniaxial tension) and viscoelastic (rheology, dynamic mechanical analysis) measurements, in combination with swelling experiments of the gels, we develop a unified model for understanding the molecular structure-property relationships to attain double network gels toward specific cell culture applications where such desired physical properties as elastic modulus, extensibility, and stress relaxation are required.