Table 2.

Comparison of different exosome characterization techniques.

Characterization method	Exosome property	Advantage	Disadvantage	Reference
Physical characterization
Electronic microscopy	Morphology, size distribution	Necessary process for nanosized exosome morphological feature characterization	Time-consuming, affected by human factors like visual sense	(64) (17)
Nanoparticle tracking analysis	Size distribution, concentration in solution	Fast and easy, in combination with microscopy for exosome physical property characterization	Unable to determine the phenotype of exosomes	(17) (65)
Biochemistry characterization
Western blotting	Presence and level of protein	Classic and standardized method for protein analysis	Low sensitivity, long preparation procedure, unable to exclude contaminants from exosomes	(71) (66)
ELISA	Presence and level of protein	Classic and standardized method for protein analysis	Expensive, unable to exclude contaminants from exosomes	(66)
Flow cytometry	Protein specificity and concentration in solution	Able to identify subpopulation of exosomes with specific protein markers	Resolution limit restricts the sensitivity, low amount of protein reduces the fluorescence signal for detection	(70)