This work stemmed from the findings that peptide self-assembly is compatible with graphitic nanostructures and demonstrated that the concept can be extended to sp3-hybridized nanocarbons too. Oxidized NDs were embedded in self-assembled peptide hydrogels at physiological pH, also at remarkable loadings as high as 80% w/w relative to the peptide, although not completely avoiding ND aggregation. At lower loadings, up to 1 mg/ml NDs (40% w/w relative to the peptide), NDs dispersibility is improved by the amphiphilic biomolecule, opening the way to the potential use of these carbon nanostructures within soft biomaterials for applications. Interestingly, peptide self-assembly is not impeded by the presence of NDs, which enable modulation of the nanocomposite viscoelastic properties, with an overall increase in stiffness. Depending on the amount of NDs present in the nanocomposite, it is also possible to increase the gel resistance against applied stress, likely because of the presence of a more interconnected fibrillary network. Microscopy and spectroscopy analyses point to non-covalent interactions between peptide fibers and NDs on their surface, with shifts in the amide signals suggestive of variations in the H-bonding network when NDs are present. Overall, this work lays the basis for the future development of nanocomposite hydrogels whereby ND properties, such as NIRresponsiveness, can be used for advanced biological applications in biosensing, imaging, targeted drug delivery and tissue engineering. Experimental Section