Two different samples of Aβ 1-40 fibrils were prepared. For sample 1 (Figure , S1b), 2 mg of Aβ 1-40 peptide (Genscript) was added to 1 mL of Milli-Q water and incubated for 1 h at room temperature (22 • C). The sample was vortexed for 1 min and an additional 500 µL of water was added, causing the solution to become turbid. The sample was then sonicated for 30 min, after which 1.5 mL of 1 M sodium chloride (NaCl) was then added to volume up the solution to 3 mL for a final concentration of 0.15 mM peptide, 0.01 % (v/v) NaN 3 , and 0.5 M NaCl. The sample was incubated at 37 • C for 54 days. For sample 2 (Figure , S1c), 1.3 mg of Aβ 1-40 peptide (GL Biochem) was dissolved in 500 µL of Milli-Q water and incubated for 10 min at room temperature (22 • C). PBS buffer (2×, pH 7.4) was then slowly added, after which aggregates could be visually oberved. The final concentration was 0.30 mM peptide and 0.01 % (v/v) NaN 3 in PBS. The sample was incubated at 37 • C for 69 days.