Figure 17.

Engineering the viscoelasticity of hydrogels to mimic that of living tissues. (A) Viscoelastic behaviors of some living tissues and hydrogels. (B) Schematic of designing alginate hydrogels with varying stress-relaxation rates by the combinatorial use of different molecular weight alginate macromers, ionic cross-linking densities, and short PEG spacers covalently linked to the alginate backbone. (C) Stress-relaxation behaviors of alginate hydrogels. (D) The stress-relaxation time scale (a), initial elastic modulus (b), and initial elastic modulus after 1-day and 7-day cultures (c), and the dry mass (d) of alginate hydrogels. Reprinted with permission from ref 37. Copyright 2016 Nature Publishing Group.