The used nanodiamonds (NDs) were of high pressure high temperature (HPHT) origin, produced by milling of HPHT-grown diamond single crystals. The NDs were purchased from Pureon (Switzerland), grade: MSY, size range: 0-100 nm, median size: 50 nm. Before use, the surface of the NDs was purified from any sp2-C residuals and the surface chemistry homogenized by annealing in air at 450 °C for 5 hours. This resulted in ND surface rich of oxygen-containing surface functional groups. Nanocomposite hydrogel formation Nanocomposite hydrogels were obtained by applying a pH switch. Firstly, Lff (5 mg) was dissolved in an alkaline sodium phosphate solution (1 ml, 0.1 M, pH 11.8) with ultrasonication for 5 minutes using a Branson Ultrasonic 3800 cleaning bath (Milan, Italy). Next, 1 ml of mildly acidic sodium phosphate buffer (0.1 M, pH 5.8) was added to reach pH neutrality and yield the peptide hydrogel that was used as a control. In the case of nanocomposites, the same protocol was modified by including the amounts indicated in the text of NDs in the alkaline sodium phosphate buffer, and sonicating for 15 min. to obtain homogeneous dispersions.