Platinum–zinc oxide as a super signal amplifier for ultrasensitive electrochemical immunodetection of CEA

Electrochemical immunosensors are essential for disease screening, diagnosis, treatment and monitoring. In this study, a novel sandwich-type electrochemical immunosensor has been constructed for the sensitive detection of tumor marker carcinoembryonic antigen (CEA) based on platinum‑zinc oxide (Pt-ZnO) nanoparticles as a signal amplification platform. Pt-ZnO has outstanding peroxidase-like activity that enables efficient catalysis of the H 2 O 2 reaction, leading to effective amplification of the current signal through numerous electron transfers. Its high specific surface area and excellent dispersion allow for immobilization with secondary antibodies through the Pt N bond. Moreover, graphene quantum dots–chitosan possesses outstanding electrical conductivity and biocompatibility, enabling it to improve interfacial electron transfer and capture more primary antibodies on its surface. The Pt-ZnO signal amplification system has achieved a wide linear range for the CEA detection, which spanned from 10 fg mL −1 to 100 ng mL −1 with the limit of detection (LOD) of 1.02 fg mL −1 . The LOD of the electrochemical immunosensor was seven orders of magnitude lower than that of the traditional enzyme-linked immunosorbent assay. Furthermore, it has viable reproducibility, stability and practicality. Hence the Pt-ZnO electrochemical immunosensor has great potential for the clinical identification of CEA.