3 hexafluoroisopropanol

The scaffolds were produced using an NF-103 (MESS, Fukuoka, Japan) electrospinning device under the conditions previously described [24 (link)]. PU-gelatin scaffolds were made at a collector rotation speed of 300 rpm, a voltage of 18.5–19 kV, and a solution flow rate of 1.1–1.2 mL/h. The electrospinning solution was composed of 3% Tecoflex EG-80A polyurethane (batch 01016300734, Lubrizol Advanced Materials, Beveren, Belgium) (w/v) and 15% gelatin from porcine skin (Sigma № G2500, Saint Louis, MI, USA) (w (gelatin)/w (PU)) in 1,1,1,3,3,3-hexafluoroisopropanol (Sigma, Saint Louis, MI, USA). After preparation, scaffolds were dried in a fore vacuum for at least 3 h to remove residual solvent before being stored in sealed zip-lock bags.
Flat films (100–120 µm thick) were obtained by casting a glass slide with 3% Tecoflex EG-80A polyurethane solution (w/v) in 1,1,1,3,3,3-hexafluoroisopropanol at room temperature (23–25 °C). After 3 days of incubation, fabricated flat films at room temperature were additionally dried using a fore vacuum to remove the residual solvent and stored in sealed zip-lock containers.

Aβ aliquots were prepared by dissolving 1 mg peptide (Bachem, Bubendorf, Switzerland, no. 4014447.1000) in 700 μL 1,1,1,3,3,3-hexafluoroisopropanol (Sigma-Aldrich) overnight at room temperature without agitation. Consequently, 1,1,1,3,3,3-hexafluoroisopropanol was removed in a vacuum concentrator. Dried peptide films were stored at −20°C until use. Any dissolution of such prepared Aβ42 aliquots started with the addition of less than 10% final volume of 10 mM NaOH before adjusting final solvent conditions. The quality of the peptide was examined by SV analysis of peptide dissolved in 10 mM NaOH, revealing $\ge$ 95% monomeric Aβ peptide (this experiment was performed in titanium cells because of their higher chemical resistance). Structures of the used fluorescence dyes are shown in Fig. S1, and a list of the dyes together with the solvent used to prepare the stock solutions is in Table S1.