Reduced Graphene Oxide/Iron-Cobalt Bimetallic Spherical MOF Nanocomposite Based Sandwich Electrochemical Sensor for Highly Sensitive Detection of Carcinoembryonic Antigen

A FeCo-MOF (metal organic framework) was synthesized via the simple room-temperature stirring. Subsequently, rGO (reduced graphene oxide) was modified. The surface of FeCo-MOF contains free -COOH groups that enable covalent bridging capture antibodies (Ab1). Next, a sandwich-type bioelectrochemical sensing platform was constructed to detect carcinoembryonic antigen (CEA). Ferrocene (Fc) was selected as the electrochemical signal tag, conjugating secondary antibody (Ab2). After optimizing the conditions, the results showed that within the concentration range of 10−3 ng/mL to 0.1 mg/mL, the electrochemical signal of ferrocene was enhanced with the antigen concentration and the current exhibited a linear relationship with the logarithm of the concentration (ng/mL) with a limit of detection of 0.3 pg/mL. To validate the system, electrochemical measurements performed by spiking CEA into human serum; the relative standard deviation (RSD) was from 2.5% to 3.6%, demonstrating a suitable approach for biochemical analysis.