A disposable amperometric enzyme immunosensor for rapid detection of Vibrio parahaemolyticus in food based on agarose/Nano-Au membrane and screen-printed electrode

Recent outbreaks of foodborne illnesses continue to support the need for rapid and sensitive methods for detection of foodborne pathogens. A disposable electrochemical immunosensor for detection of Vibrio parahaemolyticus (VP) based on the screen-printed electrode (SPE) coated with agarose/Nano-Au membrane and horseradish peroxidase (HRP) labeled VP antibody (HRP-anti-VP) has been developed in this paper. Then, the immunosensor was characterized by cyclic voltammetry (CV) and laser scanning confocal microscope (LSCM). The immunosensor was incubated with the one-step immunoassay format involving VP for 30 min at room temperature (25 0.5 degrees C). The access of the active center of HRP catalyzing the oxidation reaction of thionine by H2O2 was partly inhibited by VP, which connected on the surface of the immunosensor by immunoreaction. VP could be quantificationally detected according to the shift of reduction current while CV was used as electrochemical means to detect the products of the enzymatic reaction. Under the optimum conditions of immunoreaction and electrochemical detection, VP was rapidly detectable by sigmoidal curve method and form a linear calibration between 10(5) and 10(9) cfu/ml with an associated detection limit of 7.374 x 10(4) cfu/ml (S/N = 3). The immunosensor had acceptable specificity, reproducibility, stability and accuracy, indicating that the immunosensor could satisfy the need of practical sample detection. (c) 2007 Elsevier B.V. All rights reserved.