Maintaining the same D-L-L stereoconfiguration in the tripeptide design resulted in hydrogels with G' = 35.3 ± 2.9 kPa that withstood an applied stress up to 70 Pa (Fig. ), demonstrating that addition of Dff to Hff surprisingly did not significantly alter either its elastic modulus (Fig. ) or its kinetics (see ESI). Instead, when Dff was added to the other enantiomer, hFF, the co-assembled hydrogel reached a lower elastic modulus of G' = 15.0 ± 0.4 kPa, it displayed increased resistance to applied stress up to 100 Pa, but also significantly slower gelation kinetics (Fig. and). We inferred that the differences in the viscoelastic properties of the coassemblies could be ascribed to more heterogeneity and defects in the supramolecular packing of Dff and hFF, which are two peptides that differ not only in the N-terminal sidechain, but also in stereoconfiguration. To verify this hypothesis, we thus undertook microscopic analysis of the coassemblies to ascertain whether the viscoelastic differences could be correlated to nanomorphology.