Microfluidic Dielectrophoretic Purification of Extracellular Vesicles from Plasma Lipoproteins

Extracellular vesicles (EVs) are small lipid vesicles shed by cells, carrying proteins, nucleic acids, and other molecular fingerprints. EVs have emerged as crucial mediators of cell-to-cell communication and hold great promise as biomarkers for liquid biopsies, enabling disease screening, diagnosis, prognosis, and monitoring. However, conventional EV separation methods are hampered by the presence of lipoproteins (LPs) in plasma samples, which have comparable characteristics and significantly outnumber EVs. These LPs contaminants complicate downstream analysis, compromising the accuracy of EV-based liquid biopsies. In this study, we present a lab-on-a-chip device that utilizes dielectrophoretic (DEP) separation principles to achieve efficient separation of EVs from LPs. Our method starts with a lab-on-a-disc filtration of human blood plasma gathering similar-sized EVs and LPs, followed by on-disc buffer exchange and subsequent injection into a microfluidic chip containing slanted interdigitated microelectrodes. The DEP force is negative for all EV sizes and positive for all LP sizes at 10⁴ Hz and thus EVs are pushed away and collected at the collection outlet, whereas LPs are flowed down to the waste outlet. This two-step EVs isolation method, size-based filtration followed by DEP-based purification, offers a promising solution for enhancing the quality and accuracy of EV-based liquid biopsies.