Abstract
Electrically conductive polymers are promising materials for charge transfer from living cells to the anodes of electrochemical biosensors and biofuel cells. The modification of living cells by polypyrrole (PPy) causes shortened cell lifespan, burdens the replication process, and diminishes renewability in the long term. In this paper, the viability and morphology non-modified, inactivated, and PPy-modified yeasts were evaluated. The results displayed a reduction in cell size, an incremental increase in roughness parameters, and the formation of small structural clusters of polymers on the yeast cells with the increase in the pyrrole concentration used for modification. Yeast modified with the lowest pyrrole concentration showed minimal change; thus, a microbial fuel cell (MFC) was designed using yeast modified by a solution containing 0.05 M pyrrole and compared with the characteristics of an MFC based on non-modified yeast. The maximal generated power of the modified system was 47.12 mW/m2, which is 8.32 mW/m2 higher than that of the system based on non-modified yeast. The open-circuit potentials of the non-modified and PPy-modified yeast-based cells were 335 mV and 390 mV, respectively. Even though applying a PPy layer to yeast increases the charge-transfer efficiency towards the electrode, the damage done to the cells due to modification with a higher concentration of PPy diminishes the amount of charge transferred, as the current density drops by 846 μA/cm2. This decrease suggests that modification by PPy may have a cytotoxic effect that greatly hinders the metabolic activity of yeast.
Highlights
IntroductionMicrobial fuel cells (MFCs) convert chemical energy into electric power via microorganism-catalysed reactions [4,5]
Images obtained from the cells modified with different concentrations of PPy, it can be seen that when the concentration of pyrrole in the solution used for the modification of yeast increases, the cell size declines
Our results show that cell modification with a solution containing 0.05 M pyrrole causes minor changes in cells’ size, shape, form, and surface roughness parameters, making this concentration the most suitable for further use for yeast modification in biofuel cell anodes
Summary
Microbial fuel cells (MFCs) convert chemical energy into electric power via microorganism-catalysed reactions [4,5]. The electric charge from the ongoing substrate oxidation process during microorganisms’ metabolic processes is released and transferred towards the electrodes [5]. Microbial fuel cells require continuous electric charge release in the anode and consumption at the cathode in order to generate electrical power [6]. The MFC efficiency greatly depends on the flow of electric charge transfer from the microorganisms to the electrodes [7,8]. Many new materials applied for electrode modification are used to enhance cell performance by increasing electric charge transfer [5,9,10,11,12]
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