| This research investigated impedance biosensor for detection of Escherichia coli O157:H7. One conventional three-electrode system with a planar indium tin oxide (ITO) working electrode was developed for the detection of Escherichia coli O157:H7 through the surface immobilization of monoclonal antibody onto ITO electrode. The electrochemical behavior of the modified electrodes in the electrolyte is obtained by cyclic voltammetry and electrochemical impedance spectroscopy. Resistance and capacitance components in the frequency range from 1 Hz to 1 OOK Hz were analyzed based on validated equivalent circuits. [Fe(CN)6]3/4- redox pair is used to get the Faradaic electron impedance of the adsorbed layer.Good correlations were obtained between the concentrations of the target bacteria and the electron transfer impedance. The biosensor could detect the target bacteria with a detection limit of 4×103 CFU/mL which is competitive to most of other rapid methods, such as ELISA and DNA-based methods. A linear response in the electron-transfer resistance for the concentration of E. coli cells was found between 4×103 and 4×106 CFU/mL. The biosensor characterizes with high sensitivity, simple operation, enabling relatively rapid and reliable analysis. The result proved the prospect of EIS biosensors on application to biomedical and environmental detection of Escherichia coli O157:H7.
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