that is expected for the ν(C --O) of ss-DNA. Based on this observation the local spectra were grouped by the relative richness in aptamer molecules, i.e. their absorbance around 1700 cm -1 . It is noted that grouping of the spectra by the topography of the location of spectrum recording did not yield homogenous groups, which is attributed to the fact that the observed domains are in the lateral dimensions of the resolution limit of AFM-IR and the fact that a slight drift is always present during spectral recordings.