Disposable label-free electrochemical immunosensor based on prussian blue nanocubes for four breast cancer tumor markers

A compact and low-cost multi-electrode array (MEA) is presented, comprising four working electrodes with shared reference and auxiliary electrodes. Prussian blue was electrodeposited on the MEA using chronoamperometry with a positive potential of 0.3 V. Prussian blue nanocubes (PBNCs) were formed, which were observed using scanning electron microscopy. The precision of the four working electrodes was demonstrated using ferric/ferro cyanide (RSD <5.8%). The surface roughness of the working electrodes of the fabricated MEA was investigated by atomic force microscopy and compared with that of a commercial MEA. The PBNCs were the platform for a label-free immunosensor that detected four breast cancer tumor markers (CEA, CA125, CA153, and CA199) using specific antibodies. The processes of antibody immobilization were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The immunosensor was evaluated using real human serum samples, yielding acceptable recoveries (95.1-104.1%, RSD < 3.9) for the four tumor markers. These findings confirmed that our label-free immunosensor based on PBNCs could be a promising device for point-of-care testing and could pave the way for the establishment of new platforms for the screening of various breast cancer tumor markers.