Improved electrical wiring of microbes: anthraquinone-modified electrodes for biosensing of chlorinated hydrocarbons

The present study reports the development of a novel bioelectrochemical sensor for trichloroethene (TCE), a common subsurface contaminant, based on the measurement of the electrical current resulting from the microbially catalysed reduction of TCE at anthraquinone (AQ)-modified electrodes. Firstly, we describe the development and electrochemical characterisation of AQ-modified electrodes, prepared via spontaneous or electrochemical reduction of AQ diazonium derivatives. Finally, the proof-of-principle of the bioelectrochemical sensor for TCE was evaluated, using a TCE-dechlorinating microbial culture as the biosensing element. The response of the bioelectrochemical sensor was measured either as the peak current in cyclic voltammetry or the steady-state current in chronoamperometry; in both cases, it was found to be proportional to TCE concentrations in the range 0-100 mu mol/L. On the other hand, the microorganisms in contact with the electrode surface caused severe fouling problems which drastically reduced the life-time of the sensor.