A Sandwich-Type Electrochemical Immunosensor based on Pd Nanocubes Functionalized MoO 2 Nanospheres for Highly Sensitive Detection of CEA

In this study, a sandwich-type electrochemical immunosensor was developed for detecting carcinoembryonic antigen (CEA) effectively. The proposed electrochemical immunosensor was based on gold nanocrystals (Au NDs) as the substrate material for capturing primary antibodies and using palladium nanoscale cubics (Pd NCs) loaded on amino-functionalized MoO 2 nanospheres (Pd NCs/NH 2 -MoO 2 NSs) as a secondary antibody label. Au NDs had dendritic structures that were more conducive to capturing Ab 1 and can accelerate electron transfer. MoO 2 had the good catalytic capacity for reduction of H 2 O 2 and favourable electrical conductivity. Similarly, Pd NCs had excellent catalytic performance for hydrogen peroxide reduction. Hence, the obtained Pd NCs/NH 2 -MoO 2 NSs were more effective than Pd NCs and NH 2 -MoO 2 NSs in catalytic reduction of hydrogen attribute to a synergistic effect, showing excellent catalysis. The proposed electrochemical immunosensor had a lower detection limit of 3.3 fg ml −1 jand a wider detection range from 10 fg ml −1 to 100 ng ml −1 (S/N = 3) for the detection of CEA under optimal experimental conditions. The proposed electrochemical immunosensor showed good sensitivity, stability, selectivity, reproducibility and its good detection performance of the immunosensor indicated that it had a broad application prospect in clinical detection.