To monitor the effect of surface on aggregation of Aβ42, Aβ(14-23) and α-Syn, 1-(3-aminopropyl) silatrane (APS)-functionalized mica surfaces were used. APS-functionalized mica surfaces were prepared by incubating freshly cleaved mica into 167 μM of APS solution for 30 min, then rinsed with deionized water and dried properly with Argon stream37. The small pieces of surfaces were put inside the eppendorf tube (low protein binding tubes) containing 100 nM of protein solution [Aβ42 and Aβ(14-23)] in 10 mM sodium phosphate buffer, pH 7.0. The substrates were taken out at desired time periods and rinsed thoroughly with deionized water and dried under Argon flow for imaging in ambient condition. To compare the on-surface aggregation propensity with that of in bulk solution, a tube containing the same stock of 100 nM protein was incubated along with the tubes with surfaces. 5 μl solution was taken out from this tube and deposited onto the APS-mica at the same time periods to that of surfaces to monitor the aggregation in bulk solution. For α-Syn, a similar method as described above was adopted. The protein concentration used was 10 nM.