Highly sensitive electrochemical detection of cancer biomarker based on anti-EpCAM conjugated molybdenum disulfide grafted reduced graphene oxide nanohybrid.

An ultrasensitive, electrochemical biosensor has been fabricated by utilizing molybdenum disulfide (MoS2) grafted reduced graphene oxide (MoS2@rGO) nanohybrid as a sensing platform. Biomolecular-assisted synthetic method was adopted to synthesize MoS2@rGO nanohybrid, where L-cys was used to reduce GO. The MoS2@rGO nanohybrid exhibits improved electrochemical performance when it has been electrophoretically deposited onto the indium tin oxide (ITO) coated glass substrate. Further, epithelialcell adhesion moleculeantibodies (anti-EpCAM) specific to cancer biomarker has been covalently immobilized on the MoS2@rGO/ITO electrodes for label-free detection of EpCAM. Electrochemical results confirm that anti-EpCAM/MoS2@rGO/ITO based biosensor can detect EpCAM in the concentration range of 0.001-20 ng mL-1 with a detection limit of 44.22 fg mL-1 (S/N = 3). The biosensor's excellent analytical performance has been attributed to the efficient immobilization of EpCAM antibodies on the MoS2@rGO surface, which results in high specificity for EpCAM antigen. The fabricated biosensor showed good selectivity, reproducibility, and stability. The successful detection of EpCAM antigen in spiked samples (human saliva, serum and urine) makes this platform an alternative method for early screening of cancer biomarker.

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.