Thanks, and I appreciate. Maybe there is a misunderstanding, actually my question for this one is 'How to adhere exosome tightly to a glass surface for immunostaining'. Thanks again.

That's not so easy, partly working is drying the sample. Take your exosomes in your buffer (e.g. PBS ore HEPES), put a little drop at the slide and dry it, afterwards a little mounting medium and maybe some are still attached to the surface. Matrix coated slides should work better. For confocal microscopy its enough to mix your exosomes with mounting medium and wait o.N. Normal confocal will not resolve exosomes, so you only see your signal of the antibody, this will not represent the exact size of the exosome.

Thanks, Alex. I feel only the flow cytometry should be applied for the exact size.