Hybrid Amyloid‐Based Redox Hydrogel for Bioelectrocatalytic H₂ Oxidation

Abstract

An artificial amyloid‐based redox hydrogel was designed for mediating electron transfer between a [NiFeSe] hydrogenase and an electrode. Starting from a mutated prion‐forming domain of fungal protein HET‐s, a hybrid redox protein containing a single benzyl methyl viologen moiety was synthesized. This protein was able to self‐assemble into structurally homogenous nanofibrils. Molecular modeling confirmed that the redox groups are aligned along the fibril axis and are tethered to its core by a long, flexible polypeptide chain that allows close encounters between the fibril‐bound oxidized or reduced redox groups. Redox hydrogel films capable of immobilizing the hydrogenase under mild conditions at the surface of carbon electrodes were obtained by a simple pH jump. In this way, bioelectrodes for the electrocatalytic oxidation of H2 were fabricated that afforded catalytic current densities of up to 270 μA cm−2, with an overpotential of 0.33 V, under quiescent conditions at 45 °C.

Rational design of functional amyloid fibrillar assemblies

“…The PFD of HET-s was mutated with additional cystine at the N-terminus and the modification was achieved through a fast covalent bond formation with benzyl bromide derived methyl viologen, thus creating redox amyloid hydrogels to interact with hydrogenases for efficient electron transfer evidenced by H 2 oxidation. 137 Overall, through direct genetic fusion and indirect biological conjugation, various modified amyloid assemblies with enhanced or synergistic functions could be created for a broad range of applications.…”

“…The PFD of HET-s was mutated with additional cystine at the N-terminus and the modification was achieved through a fast covalent bond formation with benzyl bromide derived methyl viologen, thus creating redox amyloid hydrogels to interact with hydrogenases for efficient electron transfer evidenced by H 2 oxidation. 137…”