Next, Raman microspectroscopy (Figure ) was employed to further verify the distribution of NDs in the nanocomposite that TEM micrographs suggested to be absent within the peptide fibers. In particular, Raman spectra were characterized by an evident background fluorescence due to the presence of the NDs, and the characteristic intense signals at 1003 cm.1 due to the peptide phenylalanine (Phe) ring vibration, and the first-order Raman line of diamond at 1332 cm-1 corresponding to the vibrations of the diamond lattice (Figure ), which was the only signal present in the spectra of NDs alone (see ESI, Figure ). Mapping of the intensity ratio between the two main signals due to the peptide (1003 cm-1) and the NDs (1332 cm-1) confirmed absence of the NDs in the inner core of the peptide fiber (Figure 4B), in agreement with TEM micrographs. Interestingly, presence of NDs shifted other characteristic signals found in the peptide fibers, similarly to what previously observed for nanocomposites with CNOs, and suggesting non-covalent interactions between the two components. In particular, the peak attributed to the Phe aromatic ring that is normally present at 1037 cm-1 was shifted to 1034 cm-1. The amide III region, where signals arising from C-N stretching and N-H bending are found, featured a signal at 1204 cm-1 while it is found at 1207 cm-1 in the absence of NDs. We thus inferred variations in the Hbonding pattern of the peptide stacks due to non-covalent interactions with neighboring NDs. Finally, the peak at 949 cm-1 that arises from the vibrational mode of the peptide skeleton, is normally found at 952 cm-1, indicative of variations in the peptide conformation upon interaction with the NDs. Fouriertransformed infrared (FT-IR) spectroscopy further confirmed changes in the amide III region, with the main signal of the peptide gel at 1377 cm-1 being shifted to 1392 cm-1 in the ND-nanocomposite gels (Figure ).