Electrochemical biosensor for the epithelial cancer biomarker EpCAM based on reduced graphene oxide modified with nanostructured titanium dioxide.

An electrochemical immunosensor has been fabricated for the early determination of epithelial cell adhesion molecules (EpCAM, tumor biomarker) antigen using reduced graphene oxide (rGO) modified with nanostructured titanium dioxide (TiO2). The hydrothermally synthesized rGO@TiO2 nanocomposite has been electrophoretically deposited on indium tin oxide (ITO) coated glass substrate, and the deposition was confirmed using various spectroscopic, microscopic, and electrochemical techniques. The fabricated rGO@TiO2/ITO electrode shows improved electron transfer kinetics with an electron transfer rate constant of 1.93 × 10-7 cm·s-1. Furthermore, the rGO@TiO2/ITO electrodes were used for the covalent immobilization of monoclonal EpCAM antibodies. Electrochemical determination of the EpCAM cancer biomarker is achieved using differential pulse voltammetry by scanning the potential from - 0.4 to 0.8 V with an amplitude of 50 mV. The rGO@TiO2-based biosensor shows high sensitivity (3.24 μA·mL·ng-1·cm-2), wide detection range (0.01 ng·mL-1 to 60 ng·mL-1), and low detection limit (0.0065 ng·mL-1, S/N = 3). The fabricated biosensor is highly stable and regenerable and has been successfully applied to the determination of EpCAM in spiked human serum samples. Graphical abstract.