Isolation of exosomes from whole blood by a new microfluidic device

Exosomes are endocytic-extracellular vesicles with a diameter around 100 nm that play an essential role on the communication between cells. In fact, they have been proposed as candidates for the diagnosis and the monitoring of different pathologies (such as Parkinson, Alzheimer, diabetes, cardiac damage, infection diseases or cancer).

Researchers from the University of Zaragoza functionalized magnetic nanoparticles (Fe₃O₄NPs) with an exosome-binding antibody (anti-CD9) to mediate the magnetic capture in a microdevice. This was carried out under flow in a 1.6 mm (outer diameter) microchannel whose wall was in contact with a set of NdFeB permanent magnets, giving a high magnetic field across the channel diameter that allowed exosome separation with a high yield. To show the usefulness of the method, the direct capture of exosomes from whole blood of patients with pancreatic cancer (PC) was performed, as a proof of concept. The captured exosomes were then subjected to analysis of CA19-9, a protein often used to monitor PC patients. The results show that, for the cases analyzed, the evaluation of CA19-9 in exosomes was highly sensitive, compared to serum samples.

Description of the microdevice

a Operation principle of the coaxial mixer. b ELISA analysis against CD63 and CA19-9 performed after exosome capture from whole blood. c Left: Image of setup. Right: The pipe is lifted from the magnets showing the NPs captured at the junctions between the alternate polarization magnets. d Simulation of the magnetic gradient created between each pair of NdFeB magnets. Nanoparticle accumulation coincides with the high intensity nodes. The tubing is represented with the solid and dashed blue lines