Bradford kit

The preparation of Aβ1_− 42 synthetic oligomers was performed according to a previously described protocol [32 (link)]. The supernatant with Aβ_1–42 oligomers was assayed for protein content using the Bradford kit (Sigma-Aldrich). The oligomerization of Aβ_1–42 was checked by dot blotting using two different antibodies: 6E10 (beta amyloid antibody; #SIG-39320, Covance) and A11 (anti-oligomer antibody; #AHB0052, Invitrogen). 0.1 to 1 μg of each oligomeric preparation were applied on a nitrocellulose membrane and allowed to air dry. The membrane was then washed with TBS for 5 min and blocked with Odyssey Blocking Buffer (Li-Cor, #FE3092750000) for 1 h at room temperature. The membranes were then incubated overnight at 4 °C with 6E10 (1:2000) or the conformation dependent antibody A11 (1:500) in Odyssey Blocking Buffer with 0.1% Tween-20. Following 3 10-min washes, the blot was incubated with secondary antibody (anti-mouse IRDye 800, 1:2500 (Li-Cor) or anti-rabbit Alexa Flour 680, 1:5000 (Invitrogen)) for 1 h at room temperature, washed again and scanned on Odyssey Imaging System (Li-Cor).

The concentration of proteins in EVs was determined using a Bradford kit (Sigma-Aldrich) with bovine serum albumin (BSA, Sigma-Aldrich) as a standard. Lysates to be analyzed were prepared using equal amounts of Laemmli buffer lacking bromophenol blue and were further diluted during the assay (1:31) to prevent buffer constituents to be incompatible with the quantification. The assay was carried out according to the instructions of the manufacturer and samples were measured at a wavelength of 545 nm after an incubation time of 40 min at room temperature.