Figure 4.

Material properties of GelMA/NC hydrogel composite. a) A swelling assay demonstrated similar absorption characteristics of GelMA and GelMA/NC discs in DPBS. Hydrogel mass was increased for 1 day and then was retained for up to 7 days. b) An accelerated degradation assay in a 2 U/mL collagenase solution yielded similar degradation profiles of GelMA and GelMA/NC hydrogels. Total degradation in both conditions was observed after 27 h. c) SEM micrographs of GelMA and GelMA/NC demonstrated similar porous morphologies at 1,000X and 5,000X (scale bars of 100 μm and 20 μm, respectively). Pore sizes were of the same order of magnitude. The GelMA/NC group did display powdered clusters of NC (yellow arrow) in between GelMA layers as demonstrated at 5,000x. d) During muscle contraction, implanted scaffolds undergo compressive strengths, so to evaluate the ability of the scaffold to withstand compressive loading, GelMA, and GelMA/NC discs were evaluated for compressive modulus. The addition of NC in the 4% GelMA hydrogel did not statistically increase the stiffness of the hydrogel. The 4% GelMA hydrogels were significantly less stiff than the 5%, 6%, and 7% samples.