The concentration of RNA in serum samples are very low and it is quite usual to see nothing by nanodrop or GE. The suggested method is cDNA synthesis using your extracted material. If your extraction is successful, nanodrop will show a high amount of cDNA.

Good luck in your research

I wouldn't expect you to see anything on a nanodrop. Maybe try an RNA Pico agilent bioanalyser chip. Exosomal RNA should have little to no ribosomal RNA so you wouldn't see your usual bands on a gel.

Thanks for your answers. 

Prabu, I have already seen those papers.

Siamak, I will synthesize cDNA and check it out.

Navind, do you take 1 microliter RNA for RNA pico chip like nano chip? For nano chip you need to load at least 50 ng. How about pico kit?

@ Alireza,

Yep, pico chips take 1ul volume, very similar to a RNA Nano chip. From memory, pico chips have a range from 5 to 5000pg.

Having done both pico chip and small RNA chips on same samples, one can get interesting answers about their sample from both. Pico chip will demonstrate little to no rRNA and small RNA chip will give better insight as to the spectrum of small RNA species in sample.

Thank you Prabu for those great papers.

Hi, I am working on mRNA extracted from Extracellular Vesicles (including vesicles less than 220 nm in size). These vesicles are enriched from HCC plasma samples and I've got an average of 1500 ng/ul through Nanodrop. This extraction in done via Trizol method. I get the right OD between 1.8-2.2 but is this concentration from cancer patients okay??