Dumbbell-like Au-Fe3O4 nanoparticles as label for the preparation of electrochemical immunosensors.

In this work, we developed a novel kind of label based on dumbbell-like Au-Fe3O4 nanoparticles (NPs) for the preparation of electrochemical immunosensor for the detection of cancer biomarker prostate specific antigen (PSA). The signal amplification strategy, using the synergetic effect present in Au-Fe3O4 to increase the reduction ability of the NPs toward H2O2, improves the sensitivity and detection limit of the immunosensor. With primary anti-PSA antibody (Ab1) immobilized onto graphene surface and secondary anti-PSA antibody (Ab2) adsorbed onto the Au of the Au-Fe3O4 NPs, the immunosensor prepared through a sandwich structure displays a wide linear range (0.01-10 ng/mL), low detection limit (5 pg/mL), good reproducibility and stability. These labels for immunosensors may provide many potential applications for the detection of different biomolecules.