Ultrasensitive electrochemical immunosensor for SCCA detection based on ternary Pt/PdCu nanocube anchored on three-dimensional graphene framework for signal amplification

In this study, a novel and ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of squamous cell carcinoma antigen (SCCA) based on the β-cyclodextrin functionalized graphene nanosheet (CD-GN) and the ternary hollow Pt/PdCu nanocube anchored on three-dimensional graphene framework (Pt/PdCu-3DGF). CD-GN exhibited high specific surface area and good dispersibility and stability in water, which were beneficial to fix captured antibodies (Ab 1 ) through the supramolecular host-guest interaction between CD and Ab 1 . The abundant oxygen-containing functional groups on 3DGF provided binding sites for anchoring noble metal nanoparticles . Pt/PdCu-3DGF could capture detected antibodies via the interaction of Pd-NH 2 and Pt-NH 2 . Furthermore, the ternary metal nanoparticles exhibited high electrocatalytic activity toward the reduction of hydrogen peroxide. Under optimal conditions, the fabricated immunosensor showed a sensitive response to SCCA with two linear ranges. The linear ranges are 0.0001–1   ng/mL and 1–30   ng/mL with a detection limit of 25   fg/mL. Additionally, the proposed immunosensor showed good reproducibility and stability.