Droplet microfluidic platform for extracellular vesicle isolation based on magnetic bead handling

Extracellular vesicles (EVs) are rapidly gaining in popularity as biomarkers of various diseases, acting as cargoes of valuable information from the cell of origin. Despite their important value, their current use in clinical practice is still limited. Among the limiting factors, one of the most critical are the challenges regarding their isolation. In fact, conventional approaches are characterized by low purity and throughput, or poor reproducibility. Here, we present a droplet microfluidic platform specifically developed for EV isolation by affinity capture with magnetic beads. This platform is capable of processing large sample volumes (2 mL) in a relatively short time (4.5 hours), with considerable automation. In detail, EVs and magnetic beads are co-encapsulated within the same droplet, which acts promoting their mixing due to the spontaneous recirculation; this continuous agitation prevents any loss usually caused by bead sedimentation and promotes the EV capturing. Our droplet microfluidic protocol is compared to a commercially available method, showing a shorter required incubation time (about 2.5 times) and a higher capture efficiency (2.5-folds). The microfluidic approach is therefore positively evaluated in terms of protein content, EV quantification and microRNA cargo analysis.