In-situ electrochemical polymerization of dopamine at cell-electrode interface enhances the extracellular electron transfer efficiency of Shewanella

Electrochemically active bacteria (EAB) show great prospects in biofuel and biochemical engineering. Shewanella is a common EAB genus, but the extracellular electron transfer (EET) efficiency requires improvement. Previous studies have indicated that Shewanella largely relies on indirect EET using redox mediators, suggesting that direct EET efficiency is insufficient. In this study, in-situ electrochemical polymerization of dopamine (DA) at cell-electrode interface was proposed to enhance direct EET efficiency. The results demonstrated that chronoamperometry is more suitable for poly-DA (PDA) formation, increasing polymerization efficiency and reducing PDA oxidation. PDA at cell-electrode interface enhanced the outward EET efficiency by more than 17 times for Shewanella cells attached on an electrode. The enhancement is primarily attributed to that PDA at the interface established a direct conductive connection between EAB cells and an electrode, promoting direct EET. This study provides a novel approach for improving the EET efficiency of EAB.