What is the principle of the ultracentrifugation-based exosome isolation techniques?

Ultracentrifugation-based exosome isolation techniques work on the principle of using centrifugal force to separate exosomes from other particles in a biological fluid based on size and density.

One advantage of this exosome-isolation technique is that it yields a purer exosome sample that is suitable for use in clinical studies. Another advantage is that the procedure can be scaled up to isolate exosomes from larger sample volumes, making it suitable for both small-scale as well as larger clinical assays. 

The relatively complex and time-consuming process as well as the higher potential of exosome damage due to very high centrifugal forces are downsides of this technique.