Table 1 Extractions of small extracellular vesicles

Ultracentrifugation

Separation is carried out alternately by low-speed and high-speed centrifugation.

1.Gold standard.

2.The extractable sample size is large.

1.Time consuming.

2.High-speed will damage sEVs.

[29]

Density gradient centrifugation

Ultracentrifugation makes sEV gather in a specific density class.

High purity.

1.Time consuming.

2.Repeated centrifugation will damage sEVs.

[30]

Polymer sedimentation

The solubility and dispersibility of sEVs are changed by hydrophobic polymer, so that sEVs can be precipitated under relatively low centrifugal force.

1.Easy to use.

2.Low cost.

1.Miscellaneous protein pollution is much.

2.Mechanical force or chemical additives can damage sEVs.

[31]

Ultrafiltration

Solvents and small molecular substances are filtered, while relatively large molecular substances are trapped on the ultrafiltration membrane.

1.Simple and fast.

2.Low cost.

3.Good portability.

1.Impurities of the same size are difficult to distinguish.

2.Low separation efficiency.

3.The purity is low.

[32]

Immunoaffinity

Separation of sEVs with magnetic beads coated with anti-marker antibodies.

1.High specificity.

2.High purity.

1.The efficiency and the recovery rate are low.

2.The biological activity of sEVs is susceptible to pH and salt concentration.

[33]

Microfluidic Platform

Particles with different characteristics are separated by different degrees of stress in different force fields.

1.Fast.

2.Low cost.

3.Easy automation.

1.Lack of standardization of technology.

2.Lack of large-scale clinical sample testing.

[34, 35]