Hybrid Amyloid-Based Redox Hydrogel for Bioelectrocatalytic H₂ Oxidation

Area of Science:

• Biomaterials Science
• Electrochemistry
• Protein Engineering

Background:

• Efficient electron transfer is crucial for bioelectrochemical systems.
• Developing stable and effective immobilization matrices for enzymes like hydrogenase is challenging.
• Amyloid self-assembly offers a promising route for creating ordered biomaterials.

Purpose of the Study:

• To design an artificial amyloid-based redox hydrogel for mediating electron transfer between [NiFeSe] hydrogenase and electrodes.
• To create self-assembling redox-active protein nanofibrils for bioelectrode fabrication.
• To evaluate the performance of the fabricated bioelectrodes for hydrogen oxidation.

Main Methods:

• Synthesis of a hybrid redox protein by incorporating a benzyl methyl viologen moiety into a mutated HET-s prion protein domain.
• Self-assembly of the hybrid protein into structurally homogenous nanofibrils.
• Fabrication of bioelectrodes by immobilizing [NiFeSe] hydrogenase within the redox hydrogel on carbon electrodes via a pH jump.
• Electrochemical characterization of the bioelectrodes for hydrogen (H2) electrocatalytic oxidation.

Main Results:

• Structurally homogenous amyloid nanofibrils with aligned redox groups were successfully synthesized.
• The redox hydrogel effectively immobilized hydrogenase under mild conditions.
• Fabricated bioelectrodes achieved catalytic current densities up to 270 μA cm⁻² for H2 oxidation.
• An overpotential of 0.33 V was observed at 45°C under quiescent conditions.

Conclusions:

• An artificial amyloid-based redox hydrogel is a viable material for enzyme immobilization and electron transfer mediation.
• The developed bioelectrodes demonstrate efficient electrocatalytic activity for hydrogen oxidation.
• This approach offers a promising strategy for constructing advanced bioelectrochemical devices.