Table 1.

Principles and characteristics of isolation methods of EVs.

Type	Method	Principle	Advantage	Disadvantage
By density	Ultracentrifugation	Different centrifugal processes to isolate EVs based on density and mass	Easy to operate; Low cost	Low purity; Low throughput; Time-consuming
By size	Ultrafiltration	Using the filter membrane to remove large bioparticles	High purity; Time-saving	Clogging the nanopores; Damaging the structure and dissoluting EVs;
	Size exclusion chromatography	Large particles such as EVs are unable to pass through column thus rapidly eluting	High purity; Preserving the structure	The contaminations co-eluting with EVs
By solubility	Polymer precipitation	Changing the solubility of the solution	Easy to operate; Low-cost; Getting concentrated and high-yield EVs	Poor specificity; The contaminations co-precipitating with EVs
By immunoaffinity	Immunoaffinity magnetic beads; Immunoaffinity chromatography; Plate-mounted immunoaffinity	The surface markers of EVs interacting with antibody	High specificity; High purity	High-cost; Low throughput; Relying on reliable markers
Emerging methods	Microfluidics	Using various methods achieve microscale isolation based on their physical and biochemical properties	High purity; Low sample consumption; Low cost	Lack of standardization; Clogging the probe
	Asymmetric flow field-flow fractionation	Based on the particles density and hydrodynamic properties	Label-free; Gentle; Getting EVs subpopulations	Complex processes; Low throughput
	Nano-flow cytometry (nano-FCM)	Based on the particles of polydispersity, charge characteristics and surface markers	High throughput; High resolution	High cost; Professional personnel