Exosome Quantitation

Exosome quantitation assays and ELISA kits for AChE and tetraspanin-based EV measurement

You can measure extracellular vesicles by acetylcholinesterase (AChE) activity on a standard plate reader, without a nanoparticle tracking instrument, with calibration against particle standards giving kit-calibrated particle equivalents in compatible samples. AChE is not a universal EV marker and its activity does not directly equal particle number across all sample types, so pairing it with orthogonal methods such as NTA/TRPS, protein markers or contaminant analysis supports publication-quality quantification, and fluorescent substrate variants offer higher sensitivity for low-concentration samples such as urine or CSF. Surface-marker exosome ELISA kits use sandwich capture assays that immobilise EVs on tetraspanin-coated plates, then a detection antibody measures the bound particles, with tetraspanin capture-surface variants allowing selective quantification of EV subpopulations by surface marker expression. Formats span plate-reader enzymatic assays, fluorescence assays and sandwich ELISA kits.

Pick by what you need to measure.

1. Surface-marker-positive count. Choose tetraspanin sandwich ELISA.
2. Total particle count. Choose nanoparticle tracking analysis (NTA).
3. Total exosome protein. Choose BCA on the isolated pellet.
4. Caveat. The methods do not give comparable numbers. Pick one and stick with it across the study.
5. Sample matrix. Match to kit specifications.

SBI System Biosciences supplies ExoCount and tetraspanin-based quantification.