Label-free electrochemical immunosensors for the detection of zeranol using graphene sheets and nickel hexacyanoferrate nanocomposites

In this study, a novel label-free electrochemical immunosensor has been developed by immobilizing graphene sheets (GS) and nickel hexacyanoferrate nanocomposites (NiNPs) for the detection of zeranol (ZER). NiNPs were used as electron transfer mediators, and electroactivity was greatly enhanced in the presence of GS, which was ascribed to the good electron-transfer ability of GS. The modification procedure was characterized by cyclic voltammetry (CV). The detection is based on the current change of the modified electrode before and after the antigen-antibody reaction. Under optimum conditions, the detection of ZER demonstrated that the immunosensor exhibited a wide linear range of 0.05-10.0 ng mL(-1) with a low detection limit of 6 pg mL(-1). The proposed immunosensor also showed good performances such as high sensitivity, good selectivity and stability. The reliability of the developed immunosensor has been proved by the detection of ZER in river water samples with satisfactory results.