Direct impedimetric detection of exosomes and practical application in urine

Exosomes are nanoscale vesicles released from tumor-derived cells. They are very popular cancer biomarkers in non-invasive liquid biopsy diagnosis and evaluation of therapeutic response. Rapid analysis of exosomes with proteins or other biomarkers requires complex methods and has a relatively high cost. We indicate the fabrication of a biosensor for the detection of exosomes at low concentrations using immunological recognition strategies. The implementation of the biosensor consists of two steps: (i) functionalization of screen-printed electrodes (SPEs) with tetraspanin anti-CD63 antibodies and (ii) capturing exosomes by the electrode surface. Label-free detection of exosomes was successful with the Nyquist diagram, one of the main demonstrations of electrochemical impedance spectroscopy (EIS). In addition, we increased the consistency of the results by including the Bode diagrams of the measurements in our study. The proposed biosensor as a sensitive and reliable impedimetric method for detecting exosomes was established in a working range of 3.7 × 10 3 to 3.7 × 10 8 particles mL −1 with a detection limit of 2.0 × 10 3 particles mL −1 . Graphical Abstract