Preparation of α-Synuclein Aggregates

Recombinant human α-syn protein aggregates were purchased from Abcam (ab218819). These aggregates are advertised as preformed fibrils (PFFs) which was confirmed using negative-stain electron microscopy. Since we wanted to introduce smaller oligomeric species of α-syn into neurons, the PFFs were first broken down into smaller aggregates before recordings were made. PFF samples were sonicated (as in Polinski et al., 2018 (link)) for 15 min (50–60 Hz) at room temperature using a Grant Ultrasonic XUBA1 bath. Recombinant human α-syn protein in monomeric form (ab218818) was used as a control and negative-stain electron microscopy was used to confirm it was not aggregated.