Table 3.
Comparison of different exosome isolation methods
| Method | Time | Advantages | Disadvantages | |
|---|---|---|---|---|
| Density based methods | Ultracentrifugation [107] | 130 min | Relative high purity, allowing exosome isolation in large volume sample | Time consuming, bulk instruments, high speed rotation may cause deformation of exosomes. |
| Density gradient centrifugation [108, 109] | 250 min | Relative higher purity, can exclude some other EVs. | high requirement for the control of centrifugal time, centrifugal medium preparation is complex. | |
| Precipitation methods | ExoQuick™ and Total Exosome Isolation™ [110–112] | 14–16 h | Simple protocol, compatible with a variety of specimens. | time-consuming, low purity, co-precipitation of impurities such as soluble protein |
| Size based methods | Ultrafiltration [73, 113] | 140 min | Simple protocol and time-saving | Exosomes’ blocking or adherence to the filter membrane holes may cause the loss of yield. The force applied to promote the filtration may lead exosome damage, out of shape. |
| Gel exclusion chromatography [69, 110] | 6–12 h | Simple operation, preserve integrity of exosomes | bulk instrument, relatively low scalable | |
| Deterministic lateral displacement (DLD) pillar arrays [74] | 12 nL/h | High resolution, flexible particle size separation range, no particle labelling, small sample volumes | Complex parameter settings, low operability, pre-purification needed, relative high risk of clogging | |
| MicrofluidicViscoelastic Flows [75] | 200 μL/h | High purity (> 90%) and recovery (> 80%), field-free, label-free, fast, low cost, cutoff size is regulatable. | PEO is hard to remove and may influence subsequent analysis | |
| Acoustofluidic [114] | ∼25 min | Direct separation from biological fluids label-free, high yield and purity, cutoff size is flexible, automation, high reproducibility, | Aggregation of lipids in blood may greatly reduce separation efficiency. | |
| Affinity isolation methods | Immune affinity capture [89] | 240 min | high purity, milder manner for exosome isolation, preserve structure integrity of exosome. | overlook the subpopulation without affinity marker, non-specific binding, not suit for large scale exosome purification |
| EpiVeta [79] | >10 h | Peptide aptamer is versatile and easier to prepare. This coating layer can be combined with a variety of solid phase carriers. | Specimens require pre-processing and the process takes a long time, lacking verification of body fluid exosome. | |
| Lipid nanoprobe (LNP) [98] | 15 min | Fast, high yield, compatible various downstream analyses of DNA, RNA and proteins. | lack specificity, other lipid and albumin in blood could be co-purification, magnetic bead separation may cause the shrinkage of nEVs | |
| TIM4-Fc-conjugated beads [101, 115] | 4 h | high purity, preserve function of exosome. | purification efficiency decreases when the volume of the sample is over 1 mL and TIM4. inhibitors (EDTA and citric acid) existed, The separation step is complicated and requires pretreatment, yields vary greatly among different sample. | |
| Charge properties based methods | Alternating current electrokinetic microarray chip [104] | <30 min | Direct separation from plasma, label-free, in situ detection, fast | possible contamination of protein polymers with similar charging properties |
| anion-exchange (AE)-based isolation method [106] | 30 min | direct separation from plasma, high recovery efficiency (> 90%), fast, high purity. | Varying salt ion concentration may affect the structure and function of vesicles while elution, possible contamination of protein polymers with similar charging properties | |