Fig. 2 | Scientific Reports

Fig. 2

From: Phosphorylated tau in cerebrospinal fluid-derived extracellular vesicles in Alzheimer’s disease: a pilot study

Fig. 2

Illustration of the acoustic trapping process for extracellular vesicles (EVs). (a) Image of the setup (AcouTrap 2, AcouSort AB) under CC BY 4.0 (b) Schematic of the acoustic trapping capillary, with a rectangular cross-section of 2 mm in width and 200 μm in height. The acoustic field is generated through a piezoelectric transducer operating at 4 MHz, 10 Peak-to-peak voltage which produces a pressure node in the center of the capillary above the transducer. The generated acoustic field orchestrates particle alignment in the z direction via the pressure field gradient and the velocity field gradient (shaded in orange) retains the particles against the fluid flow in the x direction. (c) The depicted protocol outlines the steps for isolating EV using silica seed particles. Initially, the ultrasound is activated with frequency tracking to sustain the resonant frequency for the duration of the trapping procedure. The following steps are detailed: (c1) Stirring of silica seed particles (10 μm diameter) suspended in PBS for 60 s using a magnetic mixer, followed by the aspiration of 75 µl at a flow rate of 50 µl/min. (c2) Formation of a trapped particle cluster above the transducer by washing with 100 µl of PBS at 100 µl/min. (c3) Aspiration of CSF at 30 µl/min. (c4) Subsequent aspiration of 25 µl of PBS at the same flow rate. (c5) Non-trapped entities were removed by dispensing 200 µl of PBS at 100 µl/min. (c6) Release of the trapped EVs along with the seed particle cluster by deactivating the ultrasound and dispensing 75 µl. (inspired - Adapted from51 with permission from the journal Physical Review Applied.

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