Fig. 4.

Schematic of ultrafiltration-based exosome isolation. A Tandem-configured ultrafiltration. When biofluids pass through the two membranes, large vesicles, including cell debris, apoptotic bodies, and cells, are trapped in the 200-nm membrane, while vesicles with diameter in the range of 20–200 nm are retained on the lower 20-nm filter. B Sequential ultrafiltration. Larger particles (e.g., cells or cell debris) are first removed via a 1000-nm filter; then the filtrate is passed through a second filter with 500-kD cut-off to remove free proteins; finally, exosomes with diameters in the range of 50–200 nm are collected from the filtrate via a 200-nm filter. C Tangential flow filtration