Microfluidic\nDielectrophoretic Purification of Extracellular\nVesicles from Plasma Lipoproteins

Extracellular vesicles (EVs) are small lipid vesicles\nshed by cells,\ncarrying proteins, nucleic acids, and other molecular fingerprints.\nEVs have emerged as crucial mediators of cell-to-cell communication\nand hold great promise as biomarkers for liquid biopsies, enabling\ndisease screening, diagnosis, prognosis, and monitoring. However,\nconventional EV separation methods are hampered by the presence of\nlipoproteins (LPs) in plasma samples, which have comparable characteristics\nand significantly outnumber EVs. These LPs contaminants complicate\ndownstream analysis, compromising the accuracy of EV-based liquid\nbiopsies. In this study, we present a lab-on-a-chip device that utilizes\ndielectrophoretic (DEP) separation principles to achieve efficient\nseparation of EVs from LPs. Our method starts with a lab-on-a-disc\nfiltration of human blood plasma gathering similar-sized EVs and LPs,\nfollowed by on-disc buffer exchange and subsequent injection into\na microfluidic chip containing slanted interdigitated microelectrodes.\nThe DEP force is negative for all EV sizes and positive for all LP\nsizes at 10<sup>4</sup> Hz and thus EVs are pushed away and collected\nat the collection outlet, whereas LPs are flowed down to the waste\noutlet. This two-step EVs isolation method, size-based filtration\nfollowed by DEP-based purification, offers a promising solution for\nenhancing the quality and accuracy of EV-based liquid biopsies.