An electrochemical immunosensor based on an etched zeolitic imidazolate framework for detection of avian leukosis...

A novel sandwich-type electrochemical immunosensor for avian leukosis virus subgroup J (ALV-J) is described. The immunosensor was prepared by first modifying a glassy carbon electrode (GCE) with reduced graphene oxide that was functionalized with tannic acid and magnetite nanoparticles (rGO-TA-Fe₃O₄). Primary antibodies (Ab₁) were then deposited on the modified GCE. Hollow zeolitic imidazolate framework (eZIF) crystals functionalized with tannic acid and carrying secondary antibodies (Ab₂) and horseradish peroxidase (HRP) were used for signal amplification. The hollow eZIF crystals were found to be an excellent carrier for both Ab₂ and HRP, prompting the wider use of metal organic frameworks in electrochemical sensing. Under optimal conditions, the immunoassay afforded a detection range from 152 to 10,000 TCID₅₀ mL^-1 (where TCID₅₀ is the 50% tissue culture infective dose) and a low detection limit of 140 TCID₅₀ mL^-1 (at S/N = 3). The immunoassay is highly selective for ALV-J, and it demonstrates excellent reproducibility and operational stability. The practicability of the immunoassay for the fast detection of ALV-J was confirmed in experiments with spiked avian serum samples. Graphical abstract Schematic of a sandwich-type electrochemical immunosensor for avian leukosis virus subgroup J (ALV-J). It consists of reduced graphene oxide, tannic acid and magnetite as the sensing platform, and an etched zeolitic imidazolate framework carrying horseradish peroxidase for signal amplification.