Almost 13% of all death in the world is related to cancer. One of the major reasons for failing cancer treatment is the late diagnosis of the tumors. Thus, diagnosis at the early stages could be vital for the treatment. Serum autoantibodies, as tumor markers, are becoming interesting targets due to their medical and biological relevance. Among them, anti-p53 autoantibody in human sera is found to be involved in a variety of cancers. Regarding this issue, a novel and sensitive electrochemical biosensor for detection of anti-p53 autoantibody has been developed. For this purpose, a nanocomposite including thionine (as an electron transfer mediator)/chitosan/nickel hydroxide nanoparticles/electrochemically reduced graphene oxide (Th-CS-Ni(OH)2NPs–ERGO) as a support platform was fabricated on the surface of glassy carbon electrode via a layer-by-layer manner and characterized through common electrochemical and imaging techniques. Then, p53-antigen was immobilized on the nanocomposite and used in an indirect immunoassay with horseradish peroxidase (HRP)-conjugated secondary antibody and H2O2 as the substrate, following the typical Michaelis–Menten kinetics. Under optimized condition, two techniques, including differential Pulse Voltammetry (DPV) and Electrochemical Impedance Spectroscopy (EIS) as a label free technique, applied for the biomarker detection. The linear ranges and LODs were obtained 0.1–500 pg mL 1 and 0.001 pg mL 1 using DPV and 5–150 pg mL 1 and 0.007 pg mL 1 using EIS, respectively. Furthermore, the proposed biosensor displayed satisfying stability, selectivity, and reproducibility. According to the results, the presented protocol is promising to develop other electrochemical biosensors.
