The Novel Immunobiosensors for Detection of Escherichia coli O157:H7 Using Electrochemical Impedance Spectroscopy

Immunobiosensors were developed for detection of Escherichia coli O157:H7 based on the surface immobilization of monoclone antibodies onto indium tin oxide (ITO) electrodes. The immobilization of antibodies onto ITO chips was carried out by silanization. The effects of epoxysilane monolayer, the antibody layer on the electrochemical properties of the electrode, and the combined target bacteria were analyzed through cyclic voltammetry and electrochemical impedance spectroscopy. By using Randles model as the equivalent circuit, the concentration of the target bacteria can be quantitatively analyzed in terms of the change of electron transfer resistance. The biosensor could detect the target bacteria with a detection limit of 4times10³ CFU/mL. A linear response was found between 4times10³4times10⁶ CFU/mL. This biosensor was characterized with high sensitivity, excellent selectivity, short detection time and easy operation. It has a promising application in clinical laboratory diagnoses, environmental detection and food safety