Sandwich-Like Electrochemical Immunosensing of Squamous Cell Carcinoma Antigen Based on Gold Nanoparticles/Reduced Graphene and Toluidine Blue/UIO-66-NH2

Squamous cell carcinoma antigen (SCCA) is an important biomarker in the diagnose of cancer, so developing effective methods for its detection is of great significance. In the present work, a novel sandwich-like electrochemical immunosensing assay (STEM) of SCCA was constructed by preparing gold nanoparticle/reduced graphene-oxide (Au NPs/rGO) to immobilize primary antibody (PAb) of SCCA and UIO-66-NH2 MOFs structure to immobilize second antibody (SAb) and electroactive toluidine blue (Tb) probe. In this designed STEM assay, the prepared Au NPs/rGO nanohybrid offers the advantages in large surface area and conductivity as carrier, and UIO-66-NH2 provided an ideal platform to accommodate SAb and a large number of Tb molecules as signal amplifier. In the existence of SCCA, the current peaks of Tb from the formed STEM structure increase with the increase of SCCA level. After optimizing the related control factors, a wide linear range (0.01 pg ml−1 and 15.0 ng ml−1) and very low detection limit (0.003 pg ml−1) of SCCA was achieved, it's thus expected the designed STEM strategy has important applications for the detection of SCCA.