Monitoring of E. coli Immobilization on Modified Gold Electrode: A New Bacteria-based Glucose Sensor

Electrochemical impedance spectroscopy (EIS) technique has proved to be an effective method for monitoring the immobilization of various bioactive species such as enzymes, DNA, whole cells, and so forth. In this work we describe the development of an electrochemical whole cell based biosensor. Biotinylated fluorescent E. coli are immobilized onto a cysteamine, Sulfo-NHS-LC-biotin, and avidin modified gold electrodes. Immobilized bacteria are clearly observed using confocal microscopy. Electrochemical measurements are based on the charge-transfer kinetics of [Fe (CN)(6)](3-/4-) redox couple. The experimental impedance data were modelised with a computer. SAM assembly and the subsequent immobilization of bacteria on the gold bare electrodes greatly increased the electron-transfer resistance (Re,) and reduced the constant phase element (CPE). It's interesting to note, the hard immobilization of bacteria on the surface of electrode and do not remove during measurements. The effect of glucose addition was studied in the range of 10(-7) mu M to 10 mu M. The relation between the evolution of Re, and D-glucose concentration was found to be linear for values ranging from 10(-5) mu M to 10(-1) mu M and reached saturation for higher concentrations. Such biosensor could be applied to a more fundamental study of cell metabolism and drugs effect.