The analysis of cargo proteins in exosome subpopulations
has considerable
value in diagnostics but a translatable impact has been limited by
lengthy or complex exosome extraction protocols. We describe herein
a scalable, fast, and low-cost exosome extraction using an alternating
(AC) magnetic field to support the dynamic mixing of antibody-coated
magnetic beads (MBs) with serum samples within 3D-printed microfluidic
chips. Zwitterionic polymer-coated MBs are, specifically, magnetically
agitated and support ultraclean exosome capture efficiencies >70%
from <50 μL of neat serum in 30 min. Applied herein to the
immunocapture of neuronal exosomes using anti-L1CAM antibodies, prior
to the array-based assaying of α-synuclein (α-syn) content
by a standard duplex electrochemical sandwich ELISA, sub pg/mL detection
was possible with an excellent coefficient of variation and a sample-to-answer
time of ∼75 min. The high performance and semiautomation of
this approach hold promise in underpinning low-cost Parkinson’s
disease diagnostics and is of value in exosomal biomarker analyses
more generally.