Exosomes are cell-derived nanosized vesicles that have been recently recognized as new mediators for many cellular processes and potential biomarkers for non-invasive disease diagnosis and monitoring of treatment response. To better elucidate the biology and clinical value of exosomes, there is a pressing need of new analytical technologies capable of efficient isolation and sensitive analysis of such small and molecularly diverse vesicles.
Researchers at the University of Kansas have developed a microfluidic exosome analysis platform based on a new graphene oxide/polydopamine (GO/PDA) nano-interface. They report for the first time the GO-induced formation of 3D nanoporous PDA surface coating enabled by microfluidic layer-by-layer deposition of GO and PDA. It was demonstrated this nanostructured GO/PDA interface greatly improves the efficiency of exosome immuno-capture while effectively suppressing non-specific exosome adsorption. Based on this nano-interface, an ultrasensitive exosome ELISA assay was developed to afford a very low detection limit of 50 μL-1 with a 4-log dynamic range, which is substantially better than the existing methods.
The nano-interfaced microfluidic exosome platform (nano-IMEX)
(A) Schematic illustration of a single-channel PDMS/glass device with the exploded-view drawing highlighting the coated PDMS chip containing an array of Y-shaped microposts. (B) Surface of the channel and microposts is coated with graphene oxide (GO) and polydopamine (PDA) as a nanostructured interface for sandwich ELISA of exosomes with enzymatic fluorescence signal amplification. (C) The procedure for surface functionalization of the microfluidic chips.
As a proof of concept for clinical applications, the researchers adapted this platform to discriminate ovarian cancer patients from healthy controls by quantiative detection of exosomes directly from 2-μL plasma without sample processing. Thus, this platform could provide a useful tool to facilitate basic and clinical investigations of exosomes for non-invasive disease diagnosis and precision treatment.