Signal amplification strategy of label-free ultrasenstive electrochemical immunosensor based ternary Ag/TiO2/rGO nanocomposites for detecting breast cancer biomarker CA 15-3

Cancer Antigen 15-3 (CA 15-3) is a fast, non-invasive and reproducible significant biomarker diagnostic tool. More reliable, easy, and precise approaches for the detection of CA 15-3 are still urgently required. This study suggested a new label-free electrochemical immunosensor for the quantitative determination of the breast cancer antigen CA 15-3. Ternary silver/titanium dioxide/reduced graphene oxides (Ag/TiO2/rGO) nanocomposites were employed as a signal amplification platform for the developed immunosensor. A possible signal amplification mechanism of the amperometric detection was investigated by measuring the reduction of hydrogen peroxide and evaluating the electrocatalytic current response via the immunoreaction between CA 15-3 antibody-antigen on the surface of the developed Ag/TiO2/rGO nanocomposite immunosensor. The change in current response of the tested antigen in the presence of other interfering elements was lower than 5% revealing great selectivity in determining the breast cancer CA 15-3 antigen. Furthermore, a linear concentration 0.1-300 UmL(-1) with a correlation coefficient of 0.9996 was achieved with a very low limit of detection (0.07 UmL(-1)) in human serum samples. The outcomes ensured that the development of such type of immunosensors can open the gate to fabricate many others suitable for the early detection of tumor markers with more accuracy and convenience.