Dual gold nanostructure-based electrochemical immunosensor for CA125 detection

Abstract

With an aim to develop a sensitive immunoassay for ovarian cancer detection that has linearity over a broad range, we hereby report a dual gold nanostructure-based electrochemical immunosensor to detect ovarian cancer biomarker carcinoma antigen 125 (CA125) in serum. Gold nanorods (GNRs) are coated on indium tin oxide (ITO) and used as working electrode after immobilizing capture anti-CA125 on it. Second, gold nanoparticles (GNPs) tagged with cadmium ion (Cd2+) and another CA125 antibody is used as a probe for signal generation. A sandwich between gold nanorod-modified working electrode and GNP-based probe is formed through CA125 antigen. Direct detection of probe bound on the surface of immunosensor was done by differential pulse voltammetry (DPV) and the peak signals were directly proportional to the CA125 antigen concentration. The developed sensor has shown a detection limit of 3.4 U mL−1 with a broad linear detection range of 20–100 U mL−1. The immunosensor is stable, reproducible and has a good correlation coefficient of 0.97 for the clinical serum samples tested with the developed immunosensor and enzyme-linked immunosorbent assay (ELISA). It has the potential to detect CA125 in clinical samples which show abnormally high or low levels of CA125 in serum.