Efficient electrochemical immunosensor for detection of bovine interferon gamma-based gold nanoparticles/chitosan composite

Interferon gamma (IFN-γ) released by T lymphocytes, plays an important role in immune regulation and is also an important biomarker for the early diagnosis of bovine tuberculosis. In this work, an electrochemical immunosensor based on gold nanoparticles (AuNPs)/chitosan composite was developed for highly sensitive determination of bovine IFN-γ. AuNPs/chitosan composite shows high surface area and good hydrophilicity. The bovine IFN-γ immunosensor was prepared by immobilizing IFN-γ antibody on AuNPs/chitosan composite-modified glassy carbon electrode. The immunosensors were characterized by scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry (CV). Using horseradish peroxidase (HRP)-labeled IFN-γ antibody as amplification probe, the concentration of bovine IFN-γ can be monitored via the increasing current signal, which can be attributed to the specific immune binding between bovine IFN-γ antigen and HRP-labeled IFN-γ antibody, as well as the efficient catalysis reaction between thionine and HRP with the presence of H₂O₂. The developed electrochemical immunosensor exhibited a wide linear range of 0.01 to 30 ng/mL, and low detection limit of 0.003 ng/mL with good specificity and stability. This study provides a simple and promising method for diagnosis of bovine tuberculosis, which can be expanded to determine other biomarkers.