Electrochemical immunoassay of benzo[a]pyrene based on dual amplification strategy of electron-accelerated Fe3O4/polyaniline platform and multi-enzyme-functionalized carbon sphere label

An electrochemical immunosensor, basing on a dual amplification strategy by employing a biocompatible Fe3O4/polyaniline/Nafion (Fe3O4/PANI/Nafion) layer as sensor platform and multi-enzyme-antibody functionalized highly-carbonized spheres (multi-HRP-HCS-Ab2) as label, was constructed for sensitive detection of benzo[a]pyrene (BaP). The stable film, Fe3O4/PANI/Nafion, can not only immobilize biomolecules, but also catalyze the reduction of hydrogen peroxide, indicating an accelerated electron transfer pathway of the platform. The experimental conditions, including the concentration of Nafion, concentration of Fe3O4/polyaniline (Fe3O4/PANI), pH of the detection solution and concentrations of biomolecules, were studied in detail. Basing on a competitive immunoassay, the current change was proportional to the logarithm of BaP concentration in the range of 8 pM and 2 nM with the detection limit of 4 pM. The proposed immunosensor exhibited acceptable reproducibility and stability. This new type of dual amplification strategy may provide potential applications for the detection of environmental pollutants.

Graphical abstractSchematic representation of Fe3O4/PANI/Nafion-based immunosensor using multi-HRP-HCS-Ab2 bioconjugates as labels.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► An electrochemical immunosensor for high sensitive detection of BaP. ► A dual amplification strategy by Fe3O4/PANI/Nafion film and multi-HRP-HCS-Ab2 label. ► An accelerated electron transfer pathway by the Fe3O4/PANI/Nafion film.