A redox hydrogel protects hydrogenase from high-potential deactivation and oxygen damage



Hydrogenases are nature's efficient catalysts for both the generation of energy via oxidation of molecular hydrogen and the production of hydrogen via the reduction of protons. However, their O2 sensitivity and deactivation at high potential limit their applications in practical devices, such as fuel cells. Here, we show that the integration of an O2-sensitive hydrogenase into a specifically designed viologen-based redox polymer protects the enzyme from O2 damage and high-potential deactivation. Electron transfer between the polymer-bound viologen moieties controls the potential applied to the active site of the hydrogenase and thus insulates the enzyme from excessive oxidative stress. Under catalytic turnover, electrons provided from the hydrogen oxidation reaction induce viologen-catalysed O2 reduction at the polymer surface, thus providing self-activated protection from O2. The advantages of this tandem protection are demonstrated using a single-compartment biofuel cell based on an O2-sensitive hydrogenase and H2/O2 mixed feed under anode-limiting conditions.

Figure 1: Inactivation pathways of a [NiFe] hydrogenase and reaction layers inside a hydrogenase/viologen hydrogel.
Figure 2: Electrochemical and spectroelectrochemical experiments demonstrating protection of the hydrogenase from high potential and O2 by the redox hydrogel.
Figure 3: Biofuel cell performance test.


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The authors thank J. Henig and S. Stapf for help with synthetic aspects, P. Malkowski for purifying the [NiFe] hydrogenase from DvMF, C. Léger for discussions concerning reaction-diffusion layers, as well as the Cluster of Excellence RESOLV (EXC 1069) funded by the Deutsche Forschungsgemeinschaft for financial support.

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N.P., O.R., W.S. and W.L. conceived the study and co-wrote the paper. N.P. designed and supervised the monomer and polymer synthesis. O.R. designed, executed and interpreted all spectroelectrochemical and direct electrochemistry experiments as well as some mediated electrochemistry experiments. A.A.O. performed polymer synthesis, hydrogel film formation, mediated electrochemistry and biofuel cell experiments. N.P., O.R., A.A.O. and W.S. designed and interpreted mediated electrochemistry and biofuel cell experiments. R.W. executed monomer synthesis. S.P. contributed to polymer synthesis and characterization. J.V. prepared the biocathode for the biofuel cell.

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Correspondence to Wolfgang Schuhmann or Wolfgang Lubitz.

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The authors declare no competing financial interests.

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Plumeré, N., Rüdiger, O., Oughli, A. et al. A redox hydrogel protects hydrogenase from high-potential deactivation and oxygen damage. Nature Chem 6, 822–827 (2014). https://doi.org/10.1038/nchem.2022

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