2.9. Dynamic Light Scattering

The size of TCP-25 oligomers and their relative concentrations in solution were determined using Multi-angle dynamic light scattering (MADLS^®) on a Zetasizer Ultra (Malvern Panalytical, Ltd, Malvern, UK) using a quartz cuvette (ZEN2112) with a final volume of 75 μL. The peptide was dissolved in 10 mM Tris at pH 7.4 or in 10 mM NaOAc at pH 5 at a concentration of 300 μM immediately before the first data acquisition. The oligomerization rate was monitored at different time points (0–24 h and after 1 week) and after storage at different temperatures (RT, 4 and −20 °C).

For the peptide stored at −20 °C, time 0 refers to the reading immediately after melting. All reads were taken at 25 °C. Data were processed using the software Zetasizer Ultra-Pro ZS Xplorer version 1.31. Based on the hydrodynamic diameters, the peptide oligomers/aggregates were classified into 4 different families: small (0.4–5 nm), medium (20–150 nm), large (200–950 nm), and giant (1–5×10³ nm). For each sample, spectra were recorded three times with 11 sub-runs using the multimodal mode. In the graphs, the concentration of the oligomers belonging to different families is reported as the average ± SD.