Carbon-nanotube-caged microbial electrodes for bioelectrocatalysis.

A method to stably immobilize microbes on electrodes was developed. Resting cells of Methylobacterium extorquens AM1( Me AM1) were caged within multiwalled carbon nanotubes (MWNTs)by adding the cells to a water dispersion of MWNTs then allowing the resulting mixture to dry on electrodes. The Me AM1-MWCNTs electrode thus obtained displayed excellent activities in the bidirectional bioelectrocatalysis due to formate dehydrogenase(s) in the resting cells; formate oxidation and carbon dioxide reduction proceeded at steady-state catalytic current densities of 0.6 ± 0.1 and −0.8 ± 0.1 mA cm −2 , respectively, using methyl viologen as mediator under very mild conditions (pH 7.0, atmospheric pressure, and 37 °C). In addition, the catalytic signal was stable for more than one week under continuous operation. [ABSTRACT FROM AUTHOR]