appears in all spectra with mild intensity for aptamer-rich domains and very strong intensity in protein spectra. This could be associated with the higher contribution of these groups in the molecular structure. Also, water may remain among molecules with hydrophilic moieties, forming strong hydrogen bonds within the complex and not being removed by the drying of the sample. Nano-IR mapping at the maximum of 1660 cm -1 shows high intensity on a protein complex (figure ). Imaging of the surface-bound S protein succeeded at the amid I maximum at 1660 cm -1 as well as with the other laser at the ν(OH) at 3350 cm -1