Table 1.

Summary of common EV isolation approaches in PCa

Isolation Method	Mechanism	Advantage	Limitation	Reference
Ultracentrifugation and density gradient	Mass and density	Large sample capacity, low following cost, low background contamination (with density gradient-based approach)	Low efficiency for small sample volume, high capital cost, time-consuming, unexpected aggregation, protein lost	25, 31, 40-44
Precipitation	Surface charge or solubility change	Very easy handling, scalable, does not deform EVs	High background contamination for complex component sample (e.g. blood). Chemicals (polyethylene glycols or similar) used may impair downstream analysis	42, 45-51
Ultrafiltration	Size	Cut-off specific particle size, fast, less deformation of EVs	Limited filter lifetime, extra cleaning step, extra force, protein contamination	25, 52-54
Field-flow fractionation	Size and molecular weight	Continuous operation, fraction population for further analysis	Extra force applied to the field, protein contamination	55-57
Size-exclusion chromatography	Size and molecular weight	No extra force involved, does not deform EVs, can remove high-density lipoprotein (HDL)	Contamination from particles with similar size	58-62
Affinity interactions	Affinity binding	Specific interaction to the target, high purity	Pre-purification or combination steps may be needed, not for large scale	24, 63
Microfluid and microchips	Size, density or affinity binding	Low sample amount, fast, isolation and analysis can be integrated	Not suitable for large scale, specific design required, low EV yield	64-66