Surface-Functionalized PEDOT:PSS Interfaces for Improved Adhesion, Viability, and Extracellular Charge Transfer of Shewanella oneidensis MR-1

Abstract

Shewanella oneidensis MR-1 is an electroactive bacterium commonly employed in the design of microbial fuel cells (MFCs) due to its ability to convert organic matter to electricity. Its applicability is limited by low adhesion to the surface of the electrode, which decreases the efficiency of charge transfer and reduces the available power outputs. In this study, we aimed to improve the adhesion, viability, and extracellular charge transfer ability of S. oneidensis on the surface of electrodes modified with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), which is a conducting polymer frequently used to enhance the performance of MFCs. PEDOT:PSS-coated glass surface was modified with organic moieties, namely, glucose, sucrose, maltose, cellulose, chitosan, poly(vinyl alcohol), poly-l-lysine, and laminin. The modified surfaces were then analyzed using Fourier-transform infrared spectroscopy, energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, scanning electron microscopy, and fluorescence microscopy, and the results demonstrated an overall improvement in their chemical composition, substantial roughness, and moderate wettability. Biofilm formation was found to be significantly improved on PEDOT:PSS surface coated with glucose, resulting in 54.8 ± 1.2% increase in the amount of biomass. LIVE/DEAD analysis indicated a significantly higher percentage of live bacteria (97.5 ± 1.5%) on the PEDOT:PSS surface coated with glucose when compared to bare PEDOT:PSS (42.1 ± 2.1%). The improved adhesion of S. oneidensis on the glucose-functionalized PEDOT:PSS surface resulted in enhanced charge transfer characteristics, leading to significant decrease in charge transfer resistance at the electrode interface. Our approach shows promise in the further development of efficient renewable energy technology for bioelectricity generation.