Exosomes, nanovesicles secreted by most types of cells, exist in virtually all bodily fluids. Their rich nucleic acid and protein content make them potentially valuable biomarkers for noninvasive molecular diagnostics. They also show promise, after further development, to serve as a drug delivery system. Unfortunately, existing exosome separation technologies, such as ultracentrifugation and methods incorporating magnetic beads, are time-consuming, laborious and separate only exosomes of low purity. Thus, a more effective separation method is highly desirable. Microfluidic platforms are ideal tools for exosome separation, since they enable fast, cost-efficient, portable and precise processing of nanoparticles and small volumes of liquid samples. Recently, several microfluidic-based exosome separation technologies have been studied.
Researchers from Jilin University discuss the advantages of the most recent technologies, as well as their limitations, challenges and potential uses in novel microfluidic exosome separation and collection applications. They outline the uses of new powerful microfluidic exosome detection tools for biologists and clinicians, as well as exosome separation tools for microfluidic engineers. Current challenges of exosome separation methodologies are also described, in order to highlight areas for future research and development.
(A) Nanoparticles separation by Nano-DLD pillar array chips with gap G ranging from 25 to 235 nm and θmax = 5.7°. Smaller red particles follow a laminar flow in a zigzag mode, whereas larger blue colloids flow in a bumping mode. (B) Exosomes blocked by ”nanowire-on-micropillar“ structures and separated from cellular debris, proteins and other small particles (a) Nanowires; (b) Micropillars; (c) ”Nanowire-on-micropillar“ structures.