Max-Planck-Institut for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany.
Dalton Trans. 2018 Aug 7;47(31):10685-10691. doi: 10.1039/c8dt00955d.
In this work we present a viologen-modified electrode providing protection for hydrogenases against high potential inactivation. Hydrogenases, including O2-tolerant classes, suffer from reversible inactivation upon applying high potentials, which limits their use in biofuel cells to certain conditions. Our previously reported protection strategy based on the integration of hydrogenase into redox matrices enabled the use of these biocatalysts in biofuel cells even under anode limiting conditions. However, mediated catalysis required application of an overpotential to drive the reaction, and this translates into a power loss in a biofuel cell. In the present work, the enzyme is adsorbed on top of a covalently-attached viologen layer which leads to mixed, direct and mediated, electron transfer processes; at low overpotentials, the direct electron transfer process generates a catalytic current, while the mediated electron transfer through the viologens at higher potentials generates a redox buffer that prevents oxidative inactivation of the enzyme. Consequently, the enzyme starts the catalysis at no overpotential with viologen self-activated protection at high potentials.
在这项工作中，我们提出了一种二茂铁修饰电极，为氢酶提供了免受高电势失活的保护。氢酶，包括耐氧类，在施加高电势时会发生可逆失活，这限制了它们在生物燃料电池中的应用条件。我们之前报道的基于将氢酶整合到氧化还原基质中的保护策略，使得这些生物催化剂即使在阳极限制条件下也能在生物燃料电池中使用。然而，介导催化需要施加过电势来驱动反应，这会导致生物燃料电池中的功率损失。在本工作中，酶被吸附在共价附着的二茂铁层的顶部，这导致了混合的、直接的和介导的电子转移过程；在低过电势下，直接电子转移过程产生催化电流，而在更高电势下通过二茂铁的介导电子转移产生氧化还原缓冲，防止酶的氧化失活。因此，在没有外加过电势的情况下，酶开始催化，而二茂铁在高电势下自我激活保护。
