We report the successful assembly of a tripeptide in the presence of nanodiamonds (NDs) into nanocomposite hydrogels. The presence of NDs does not hinder peptide self-assembly and gelation, whilst improving the viscoelastic properties of the hydrogels. Gelation kinetics are not affected by NDs, while the elastic moduli of the peptide hydrogels are significantly increased by the NDs. Increased resistance of the gels against applied stress can also be attained depending on the amount of NDs loaded in the nanocomposite. Raman micro-spectroscopy and TEM confirmed the presence of NDs on the surface, and not in the interior, of peptide nanofibers. Peptide-ND non-covalent interactions are also probed by Raman and Fourier-transformed infrared spectroscopies. Overall, this work enables the embedding of NDs into nanocomposite hydrogels formed through the self-assembly of a simple tripeptide at physiological pH, and it provides key insights to open the way for their future applications in biomaterials, for instance exploiting their luminescence and near-infrared responsiveness.
