TABLE 1.

Strategies for exosome separation.

Isolation strategy	Principle	Advantages	Disadvantages
Differential ultracentrifugation	Particles with different density, size and mass show different deposition rates under centrifugal force.	• Suitable for mass preparation • Low cost	• Centrifuge equipment needed • Time-consuming • Risk of contamination
Density-gradient separation	Exosomes further separated by density in density gradient media	• High purity	• More complex operations • Time-consuming
Ultrafiltration	Selective separation of exosomes with specific particle size by using a filter membrane with a specific molecular weight interception value	• Low cost • Fast procedure • High purity of products	• Exosome membrane blockage • Exosome deformation
Size exclusion chromatography	Particles are eluted if larger than pore size of the porous polymer	• High purity of products • Fast procedure • Suitable for blood plasma • Maintain the shape of exosome	• Low output • Limited in large samples.
Co-precipitation	The highly hydrophilic polymer interacts with the water molecules around the exosome to reduce the solubility of exosomes, resulting in precipitation	• Easy to use • Low equipment requirement • Fast procedure	• Protein pollution • Require complicated clean-up steps
Immunoaffinity capture	Based on the specific binding of exosome surface protein markers to the corresponding antibodies	• Isolation of exosomes from specific sources • High purity of products	• High-cost antibodies • Low output