Inorganic iron-sulfur clusters enhance electron transport when used for wiring the NAD-glucose dehydrogenase based redox system

Abstract

Wiring the active site of an enzyme directly to an electrode is the key to ensuring efficient electron transfer for the proper performance of enzyme-based bioelectronic systems. Iron-sulfur complexes, the first link between proteins and mediating molecules in the biological electron transport chain(s), possess an intrinsic electron transport capability. The authors demonstrate the application of inorganic iron-sulfur clusters (Fe-S) viz. FeS, FeS2, Fe2S3, and Fe3S4, as molecular wires to mediate electron transport between a glucose-selective redox enzyme and the gold electrode. It is shown that Fe-S can emulate the functionality of the natural electron transport chain. Voltammetric studies indicate a significant improvement in electron transport, surface coverage, and resilience achieved by the Fe-S-based glucose anodes when compared to a conventional pyrroloquinoline quinone (PQQ)-based electrode. The Fe-S-based glucose anodes showed glucose oxidation at a potential of +0.5 V vs. Ag/AgCl with Tris-HCl buffer (pH 8) acting as a carrier. The current densities positively correlated with the concentrations of glucose in the range 0.1–100 mM displaying detection limits of 0.77 mM (FeS), 1.22 mM (FeS2), 2.95 mM (Fe2S3), and 14.57 mM (Fe3S4). The metal-anchorable sulfur atom, the strong π-coordinating iron atom, the favorable redox properties, low cost, and natural abundance make Fe-S an excellent electron-mediating relay capable of wiring redox active sites to electrode surfaces. Graphical abstractSchematic representation of inorganic iron-sulfur clusters used as molecular wires to facilitate direct electron transfer between NAD-glucose dehydrogenase and the gold electrode. The iron-sulfur based glucose anodes improve current response to selectively sense glucose concentrations in the range 0.1–100 mM. Electronic supplementary materialThe online version of this article (10.1007/s00604-018-2871-x) contains supplementary material, which is available to authorized users.

Perspective—Challenges in Developing Wearable Electrochemical Sensors for Longitudinal Health Monitoring

“…Bioengineering strategies to realize artificial enzyme derivatives with exposed active sites have also been explored to create optimal recognition elements for electrochemical sensors. 43 In summary, enzymes are weak candidates for reusable sensors, even though they provide enviable chemo-specificity. Finding artificial substitutes that are cheaper and produced in bulk is desired, particularly for longterm health monitoring.…”

Interspecies interactions mediated by conductive minerals in the sediments of the Iron rich Meromictic Lake La Cruz, Spain

“…3), of which magnetite and iron sulfides have been documented to facilitate mineral mediated syntrophy (Liu et al, 2012(Liu et al, , 2015Zheng et al, 2017;Kato & Igarashi, 2018). Fe-sulfides, like pyrite have been also shown to aid long-range extracellular electron transfer from cells (Kondo et al, 2015) or enzymes (Mahadevan & Fernando, 2018) to electrodes. Moreover La Cruz sediments also contain coal particles (Romero-Viana et al, 2011), which are conductive (Fig.…”

Proteomic Analysis of Methanococcus voltae Grown in the Presence of Mineral and Nonmineral Sources of Iron and Sulfur

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