Flexible Paper-Based Immunosensor for the Detection of Specific Cancer-Derived Exosomes


 This study aims at an electrochemical paper-based device for the selective and sensitive detection of exosomes as an economical and flexible platform. Using a laser cutter, a three-electrode platform was patterned on a hydrophobic paper and then synthetic carbon and silver ink were screen-printed onto the paper. Anti-human CD9 antibody was covalently attached to the surface of a carbon ink electrode enriched with graphene oxide aerogel/CoFe2O4@chitosan nanocomposite. The immobilization, incubation, and binding time of the capture antibody were investigated as effective parameters. Under optimum conditions, the differential pulse voltammetry data were used to establish a calibration plot that covered 500 to 5×106 exosoms/µL with a detection limit of 100 exosome/µL. This method was implemented successfully for the detection of exosomes in a serum sample. As the results show, the fabricated biosensor is capable of detecting exosomes for the early diagnosis of cancers.