Tuning Redox Potential of Anthraquinone-2-Sulfonate (AQS) by Chemical Modification to Facilitate Electron Transfer From Electrodes in Shewanella oneidensis

Abstract

Bioelectrochemical systems (BESs) are emerging as attractive routes for sustainable energy generation, environmental remediation, bio-based chemical production and beyond. Electron shuttles (ESs) can be reversibly oxidized and reduced among multiple redox reactions, thereby assisting extracellular electron transfer (EET) process in BESs. Here, we explored the effects of 14 ESs on EET in Shewanella oneidensis MR-1, and found that anthraquinone-2-sulfonate (AQS) led to the highest cathodic current density, total charge production and reduction product formation. Subsequently, we showed that the introduction of -OH or -NH2 group into AQS at position one obviously affected redox potentials. The AQS-1-NH2 exhibited a lower redox potential and a higher Coulombic efficiency compared to AQS, revealing that the ESs with a more negative potential are conducive to minimize energy losses and improve the reduction of electron acceptor. Additionally, the cytochromes MtrA and MtrB were required for optimal AQS-mediated EET of S. oneidensis MR-1. This study will provide new clues for rational design of efficient ESs in microbial electrosynthesis.

Anthraquinone-2-Sulfonate as a Microbial Photosensitizer and Capacitor Drives Solar-to-N2O Production with a Quantum Efficiency of Almost Unity

“…denitrificans (Figure S3) (from 95 to 94%) and the morphology features of bacteria (Figure S4) did not significantly change after mixing with 2.0 mM AQS solution for 10 days, indicating the biocompatibility of AQS to T. denitrificans . A recovery experiment shows that AQS was not absorbed or taken up by T.…”

“…The ratio of live to dead T. denitrificans (Figure S3) (from 95 to 94%) and the morphology features of bacteria (Figure S4) did not significantly change after mixing with 2.0 mM AQS solution for 10 days, indicating the biocompatibility of AQS to T. denitrificans. 20 A recovery experiment shows that AQS was not absorbed or taken up by T. denitrificans because the recovered concentration of AQS ([AQS]) from the AQS/T. denitrificans mixture was consistent with the input [AQS] (Figure 1B).…”

“…Anthraquinone (AQ) molecule is a high-energy pseudocapacitive material via storing electrons in the form of the reductive state (H-AQ) . It is a well-known electron shuttle and the H-AQ is a bioavailable electron donor for electroactive bacteria. , Interestingly, AQ is of photochemical activity and H-AQ can be formed via the direct irradiation of AQ with a substrate . Upon irradiation, AQ can induce the electron transfer of 3 AQ* with an electron donor molecule (D–H), forming an AQ radical anion (AQ •– ).…”

Three-Stage Conversion of Chemically Inert n-Heptane to α-Hydrazino Aldehyde Based on Bioelectrocatalytic C–H Bond Oxyfunctionalization

“…First, the reductive potential of alkG (−0.24 V vs SCE) is within the range of many AQ moieties, rendering sequential electron transfer from AQ mediator to alkB via alkG, and thermodynamically feasible. ,, Second, AQ moieties undergo extremely rapid and reversible two-proton-coupled two-electron transfer mechanisms especially in aqueous media (Scheme S1). , Resultantly, the rich redox chemistry of AQs extends to microbial fuel cells, redox flow batteries, solar cell devices, redox-dyes, antioxidants, antitumor agents, molecular electronics, wastewater treatment, and other energy storage systems. ,− Third, quinones, as natural electron acceptors/donors in key biological processes (e.g., photosynthesis, neurotransmission, and cellular signaling), are typically biocompatible and nontoxic to most biocatalysts. , Quinones have good biocatalytic redox active site accessibility because the quinone/hydroquinone redox function occurs across membranes or interfaces . Finally, AQs are relatively small, prototypically hydrophobic, and aromatic polyketide rings .…”