A Nonenzymatic Electrochemical Immunosensor for Ultrasensitive Detection of Tumor Biomarkers Based on Palladium Nanoparticles Conjugated Reduced Graphene Nanosheets.

A nonenzymatic electrochemical immunosensor based on palladium nanoparticles conjugated reduced graphene nanosheets (Pd-GS) for sensitive detection of cancer biomarker a-fetoprotein (AFP) is described. Primary antibody-AFP (Ab1) was immobilized onto the surface of reduced graphene nanosheets (rGO) through an amidation reaction between the carboxylic acid group of the rGO and the available amine groups of Ab1. Pd-GS which was prepared by one-spot synthesis is employed to immobilize secondary antibody (Ab2). The resulting Pd-GS-Ab2 conjugate was used as a label for the immunosensor to detect AFP. The amplified immunoassay exhibits high sensitivity, wide linear rang (0.01-10 ng/mL), low detection limit (3.0 pg/mL), acceptable stability and reproducibility. And such immunosensor also shows good recovery in the assay results for AFP in human serum samples.