Redox-active antioxidants enable highly stable bio-electrochemical systems

Area of Science:

• Biotechnology
• Electrochemistry
• Environmental Science

Background:

• Efficient interfacial electron transfer is crucial for bio-electrochemical systems (BES) in energy, environmental, and bioelectronic applications.
• Oxygen infiltration severely impairs BES performance by disrupting electron transfer processes.

Purpose of the Study:

• To investigate plant-sourced antioxidants as stable electron shuttles for BES.
• To assess the efficacy of fraxetin in maintaining electron transfer under oxygen exposure.

Main Methods:

• Electrochemical analysis was performed to evaluate electron transfer efficiency.
• Density functional theory (DFT) was used to understand the thermodynamic stability and redox properties of electron shuttles.
• Comparative studies were conducted using Shewanella oneidensis MR-1 with flavin mononucleotide and fraxetin as electron mediators under varying oxygen conditions.

Main Results:

• Fraxetin demonstrated high thermodynamic stability and resistance to oxygen oxidation, unlike flavin mononucleotide.
• Electron transfer mediated by fraxetin showed only an 18% current decrease under saturated dissolved oxygen.
• In contrast, flavin mononucleotide-mediated electron transfer saw a 75% current decrease under similar conditions.

Conclusions:

• Fraxetin serves as a robust, oxygen-tolerant electron shuttle, enabling sustained interfacial electron transfer in BES.
• This antioxidant-based strategy offers a practical alternative to physical oxygen-exclusion methods for real-world BES applications.