We inferred that a lower ND level (i.e., 0.5 mg/ml) was not sufficient to exert a significant effect, whilst higher ND amounts (i.e., 2.0 mg/ml) were detrimental because of excessive ND aggregation (see Figure bottom panels). To verify this hypothesis, TEM analyses were performed on the nanocomposite hydrogels (Figure ). A network of peptide fibers surrounded by NDs was present in all cases (Figure ), although peptide fiber diameters' (Figure ) were significantly smaller for the Intermediate level of NDs (i.e., 1.0 mg/ml). Clearly, at this amount NDs interfered with the ability of peptide fibrils to bundle into larger fibers, while higher ND loading drove their aggregation, effectively resulting in a distribution of fiber diameters similar to the lowest ND loading. Considering that there is the same peptide concentration in all tested samples, the presence of thinner peptide fibers in the case of nanocomposites with 1.0 mg/ml NDs. likely results in more interconnection points within the network that would explain the observed higher resistance against applied stress.