A label-free amperometric immunosenor based on multi-layer assembly of polymerized o-phenylenediamine and gold nanoparticles for determination of Japanese B encephalitis vaccine

A label-free amperometric immunosensor for fast and sensitive assay of Japanese B encephalitis vaccine is presented. Antiserum of Japanese B encephalitis were immobilized on bilayer nano-Au/o-phenylenediamine polymer film with deposited Prussian blue as an electronic mediator on the Pt electrode. The electrochemical behavior of the biosensor was studied with Fe^2+/3+ as probe on the Pt surface using cyclic voltammetry technique. The variation of amperometric response to the concentration of Japanese B encephalitis vaccine, the target antigen, was evaluated by cyclic voltammetry in PBS. The immunosensor showed a specific response to Japanese B encephalitis vaccine in the range 1.1 × 10⁻⁸ to 1.9 × 10⁻⁶ lg pfu/ml (pfu/ml is plaque forming unit and lg is common logarithm) with a detection limit of 6 × 10⁻⁹ lg pfu/ml. The correlation coefficient is 0.9955. The incubation time, incubation temperature, pH, reproducibility and stability of the immunosensor were also studied. The present work supplied a promising test method for biological products.