To test that the observed enhancement effect of the surface is not limited to Aβ peptides, we performed surface-aggregation experiments with α-synuclein (α-Syn) protein. Given that α-Syn is more than three times larger than Aβ-42 and the fact that we were previously able to image α-Syn monomers20, we anticipated being able to visualize the formation of oligomers starting with dimers. The surface-mediated aggregation experiment was carried out similarly to the analyses described above. Similar to the experiments with Aβ peptides, mica sheets were incubated in 10 nM α-Syn solution for different time-periods and imaged with AFM. Typical AFM images for samples corresponding to 0 h, 24 h and 48 h incubation times are shown in Fig. 3A. A few globular features were seen in the initial sample (plate (i)). To characterize their sizes, volume measurements as described in ref. 20 were performed. These measurements are shown in Fig. 3B(i) and they indicate that these features are monomers. After 24 hours (Fig. 3A, plate ii), the particles become brighter and larger in size; the volume measurements (Fig. 3B(ii)) are consistent with the formation of oligomers larger than dimers. Longer incubation (48 hours) leads to the formation of aggregates with a broad range of sizes as evidenced by images in plate (iii) and the corresponding volume distribution (Fig. 3B(iii)). Control experiments for α-Syn aggregation in the bulk solution (Fig. 3C) did not reveal such a pronounced aggregation. Even after a 24 h incubation, the bulk solution did not show aggregates (Fig. 3C, plate ii). The volume measurements for the 48 h sample reveal a major peak at 39 nm3 which is very close to the monomer volume (Fig. 3D)20. There is a secondary minor peak with a volume value of 66 nm3 that can be assigned to dimers-trimers.