Figure 4.

Isolation and drug loading methods of EVs. The commonly used isolation methods mainly utilize the physical properties and biological specificity of EVs. For example, A) differential ultracentrifugation (DU) and density gradient flotation (DGF), B) polymer precipitation-based isolation, C) ultrafiltration, D) immunoaffinity chromatography, E) size exclusion chromatography (SEC), F) flow field-flow fractionation (FFFF), and G) microfluidic technology can realize the isolation of EVs. H) Drug loading methods can be divided into endogenous and exogenous. Endogenous drug loading enables the drug to be added into the source cells of EVs, while exogenous drug loading directly loads the drug into EVs. Specific methods include endogenous drug loading, incubation, electroporation, sonication, extrusion, and freeze-thaw cycles.