Electrochemical immunosensor for detecting carcinoembryonic antigen using hollow Pt nanospheres-labeled multiple enzyme-linked antibodies as labels for signal amplification

Herein, a sensitive and specific electrochemical immunosensor is constructed for the detection of carcinoembryonic antigen (CEA) using Au–TiO2 nanoparticles as the sensor platform and multiple horseradish peroxidase (HRP)-labeled antibodies (HRP-Ab2) functionalized hollow Pt nanospheres (HPtNPs) (abbreviated as HRP-Ab2–HPtNPs) as labels. Three-dimensional (3D) Au–TiO2 nanoparticles were uniformly assembled on a glass carbon electrode (GCE) for the immobilization of primary antibodies (Ab1), which provided a biocompatible immobilization surface and a facile pathway for the electron transfer. After capturing the target CEA, the HRP-Ab2–HPtNPs bioconjugates were bound to the electrode surface via the formation of a sandwich complex. The electrochemical signals were amplified by HPtNPs and the carried HRP toward the reduction of H2O2 using hydroquinone (H2Q) as the electron mediator. Under optimized conditions, the proposed immunosensor showed a high sensitivity and a wide linear range from 0.02 to 120 ng/mL with a low detection limit of 12 pg/mL.

► A new immunosensor for detecting CEA was constructed based on Au–TiO2 and HRP–Ab2–HPtNPs.
► The 3D Au–TiO2 with large surface area and good biocompatibility could efficiently carry proteins.
► HRP–Ab2 were labeling by HPtNPs, which could load numerous HRP–Ab2 and result in a synergy with HRP.
► The immunosensor showed a high sensitivity and a wide linear range from 0.02 to 120 ng/mL toward CEA.