A Label-Free Immunosensor for CEA Based on Pd-Ir Bimetallic Nanoparticles

In this paper, a kind of label-free immunosensor for rapid detection of carcinoembryonic antigen (CEA) based on Pd-Ir bimetallic nanoparticles as a catalyst was prepared. CEA antibody (anti-CEA) was immobilized onto the surface of glassy carbon electrode through the adsorption effect of Pd-Ir bimetallic nanoparticles modified on the electrode using chitosan. When CEA antibody combines with CEA antigen, the formed immunocomplexs blocks the catalytic activity of Pd-Ir bimetal nanoparticles to the reduction of H2O2, leading to decrease in the current response signal. The decrease of the current response of the immunosensor has a linear relationship with the concentration of CEA ranging from 0.05 ng/mL to 50 ng/mL with a detection limit of 0.017 ng/mL at 3 sigma. The sensor provides a new simple method for the determination of CEA.