Hello Richard.

There are many discussions on exosomal protein assays in both pro- and against sides. Have a good read at link. https://www.researchgate.net/post/How_can_I_quantify_exosomes_ug_ml_after_purification_without_performing_protein_extraction10

Regards.

Is your question that you want to quantify a specific exosomal protein?

This should be possible but Western Blot to do it is a bit tricky.

As a prerequisite you need samples of the purified rotein of known concentration for calibration on the same blot together with your samples. For calibration at least 3 different amounts of protein should be applied.The quality of the used antibody is then important. Next, the method for detection has to be standardized (for example luminescence). The signals obtained by your samples should be within the range of your calibration curve. Be sure that you are not at the upper limit of detection.

Peter

Traditionally quantification of exosomes has been carried out by NTA, but it is not a very common device in life sciences laboratories.

It could be possible to set up a semi-quantitative protocol for WB, but in my humble opinion, with a highly sensitive kit, it would be a better alternative (more sensitivity, smaller amount of sample, specific detection by double labeling, etc.) set up detection and quantification exosome protocol by Flow Cytometry. http://www.immunostep.com/content/34-protocols

Ricardo

Thank you everyone for your valuable suggestions and the informative link. As Peter suggested, i will do western with samples and known concentration of protein followed by calibration curve and quantification. Few kits like ExoElisa can be used but it can only quantify the exosome content but not the desired protein in the exosome.