An ultrasensitive squamous cell carcinoma antigen biosensing platform utilizing double-antibody single-channel amplification strategy

• A double-antibody signal-channel amplification immunosensor was fabricated for the first time.
• Pd icosahedron was first used in the biosensor as a connecter.
• The modified mercapto-graphene sheets exhibited excellent physical and chemical property.
• The novel immunosensor possessed good sensitivity.

A novel electrochemical immunosensor was developed for ultrasensitive detection of squamous cell carcinoma antigen (SCCA), which was based on the double-antibody single-channel amplification strategy. For the first time, human immunoglobulin antibody (anti-HIgG) was used as the supporting framework to amplify the loading quantity of SCCA antibody (anti-SCCA). In this strategy, SCCA can be detected without using mesoporous nanometers to amplify the signal. In addition, Pd icosahedrons were first used as the connecter to immobilize the antibodies and strengthen the sensitivity. Only one touch point exists under the limited condition between a sphere and another shape in geometry, thus the Pd icosahedron is an excellent candidate as the role of connecter. Gold nanoparticles (Au NPs) decorated with mercapto-functionalized graphene sheets (Au@GS) were synthesized as the transducing materials. The fabricated immunosensor exhibited an excellent detection limit of 2.8 pg/mL and wide linear range of 0.01–5 ng/mL. This kind of immunosensor would provide a potential application in clinical diagnosis.