, respectively. In the CTPR8Y 16 -C 60 A co-assembly, however, the A g (2) mode was shifted towards lower frequencies at 1457 cm -1 (Fig. ). This significant downshift of the Raman A g peak for the CTPR8Y 16 -C 60 A hybrid material suggests possible electronic interactions between the protein and the electron-acceptor C 60 , which is in agreement with previous findings for the non-covalent modification of fullerene with electron donor units. In the current case the presence of electron donor aromatic residues in the protein favour the interaction with the fullerene surface through - and OH••• interactions. Cryo-electron microscopy was employed to gain structural insights into the protein-fullerene assemblies. Well-defined structures with highly distinct features were visible in the micrographs of the CTPR8Y 16 -C 60 A assembly (Fig. ). 3D analysis of the structures revealed that the protein-fullerene hybrids assemble into thin 2D sheets of irregular shape, that are mostly flat, but may have a small twist (Fig. ). The sheets are ca. 2 nm thick, with dimensions of 20 nm  20 nm on average, although reaching up to 50 nm (more precise measurements are not possible, as it is impossible to determine the precise orientation of the objects in vitrified drops). From a side view, the sheets appear made up of two parallel high contrast bands of ca. 0.7 nm, with a low contrast band of similar thickness between. The thickness of the film is consistent with a monolayer of CTPR protein, and the high contrast bands suggest the fullerenes are (predominantly) assembling on the surfaces of the protein monolayers. From face view, the plaques have very low contrast due to their thickness, but they are identifiable due to a very strong diffraction pattern, which indicates that the assemblies are ordered on the molecular level. As the particles are dispersed in the vitrified fluid, diffraction patterns from individual aggregates can be studied (Fig. ). The observed interplanar spacing can be divided into two groups, localized in the 0.85-0.79 nm region and the region between 0.50 nm and 0.40 nm. The observed interplanar distances are consistent with the diffraction signal from ordered fullerenes, as the distances are far too big for salt crystals, but far too small to originate from crystallised protein. The observed variability of diffraction distances could be a consequence of differing orientations of the ordered assemblies within the vitrified fluid, exposing diffraction patterns from different planes, or could signify that slightly different arrangements are possible for the fullerenes.