To directly test the hypothesis that surface interactions facilitate the self-assembly of amyloidogenic polypeptides, we performed systematic AFM studies of the on-surface aggregation of full size Aβ-42, Aβ(14-23) peptide and α-Syn protein at the nanomolar range. The on-surface aggregation schematically is shown in Fig. 1A. The mica sheets functionalized with 1-(3-aminopropyl) silatrane (APS) were immersed in a 100 nM solution of Aβ-42 in 10 mM sodium phosphate buffer (pH 7.4). After a certain incubation time, a mica sheet was removed from the solution, rinsed with water, dried and imaged with AFM. The samples were prepared for incubation times 0 h, 24 h, 48 h and 72 h, and typical images are shown in Fig. 1B, plates i-iv, respectively. The surface for the initial sample (0 h, plate (i)) is clean, but globular aggregates appear after a 24 h incubation time (plate (ii)), and the surface is quite densely coated with aggregates after 48 h (plate (iii)). The aggregate sizes are larger for the 72 h sample (plate (iv)). In parallel with the on-surface aggregation, aggregation of the same solution of the protein in the absence of a mica surface (aggregation in the bulk solution) was performed. A set of typical images is shown in Fig. 1C. No aggregation was detected for these samples. Only after 72 h of incubation in the bulk solution, a few globular features are noticeable (Fig. 1C, plate viii).