Small Extracellular Vesicles Detection by Dielectrophoresis-Based Microfluidic Chip Filled with Transparent Antibody-Conjugated Microbeads for Breast Cancer Diagnosis.

Small extracellular vesicles (sEVs) are ideal biomarkers for early diagnosis of tumors, but their low density and small size make them difficult to enrich and detect in body fluid samples. This study combined dielectrophoresis (DEP) with immunoaffinity methods and proposed a novel, fast, and efficient acDEP-sEV immunochip, in which by filling the chip reaction chamber with antibody-conjugated microbeads, a nonuniform electric field can be constructed, laminar flow can be disrupted, mass transfer efficiency can be improved, and fluorescence signals can be focused, ultimately achieving rapid, sensitive, and adjustable sEVs capture and detection. This method only requires 20-50 μL of plasma sample for liquid biopsy in less than 35 min. We analyzed total sEVs, EpCAM, and MUC1 positive sEVs in clinical plasma samples, and found that the combined evaluation of multiple sEVs biomarkers has extremely high sensitivity, accuracy, and specificity. Meanwhile, the chip also achieved a low limit of detection of 54 sEV/μL. This hybrid approach provides a new strategy for achieving rapid and sensitive liquid biopsy of cancer and other diseases based on sEVs.