New Ultrasensitive Sandwich-Type Immunoassay of Dendritic Tri-Fan Blade-like PdAuCu Nanoparticles/Amine-Functionalized Graphene Oxide for Label-Free Detection of Carcinoembryonic Antigen

The early detection of tumor markers has an effective role in the treatment of cancer. Here, a new sandwich-type electrochemical immunosensor for early label-free detection of the cancer biomarker carcinoembryonic antigen (CEA) was developed. Dendritic tri-fan blade-like PdAuCu nanoparticles (PdAuCu NPs)/amine functionalized graphene oxide (NH(2)-GO) were the label of secondary antibodies (Ab(2)), and Au nanoparticle-decorated polydopamines (Au/PDA) were immobilized on a screen-printed carbon electrode (SPCE) as the substrate materials. Dendritic tri-fan blade-like PdAuCu NPs/NH(2)-GO was synthesized according to a simple hydrothermal procedure and used to immobilize antibodies (Ab(2)) with large surfaces areas, increased catalytic properties and good adsorption to amplify the current signals. Subsequently, Ab(2)/PdAuCu NPs/NH(2)-GO catalyzed the reduction of H(2)O(2) in the sandwich-type immunoreactions. Under optimal conditions, the immunosensor exhibited a satisfactory response to CEA with a limit detection of 0.07 pg mL(−1) and a linear detection range from 0.1 pg mL(−1) to 200 ng mL(−1). The proposed immunosensor could be suitable enough for a real sample analysis of CEA, and has clinical value in the early diagnosis of cancer.