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Updated: Apr 12, 2026

Characterizing Electron Transport through Living Biofilms
Published on: June 1, 2018
High current density PQQ-dependent alcohol and aldehyde dehydrogenase bioanodes
Sidney Aquino Neto1, David P Hickey2, Ross D Milton3
1Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil; Departments of Chemistry and Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112, United States.
Pyrroloquinoline quinone (PQQ)-dependent enzymes show promise for biofuel cells. Mediated electron transfer (MET) bioanodes using ferrocene-modified polymers offer efficient energy conversion for ethanol oxidation.
Area of Science:
- Biotechnology
- Electrochemistry
- Renewable Energy
Background:
- Biofuel cells offer a sustainable energy alternative.
- Pyrroloquinoline quinone (PQQ)-dependent enzymes are crucial for ethanol oxidation.
- Efficient electron transfer is key for bioanode performance.
Purpose of the Study:
- To investigate PQQ-dependent alcohol and aldehyde dehydrogenase (ADH and AldDH) for ethanol bio-oxidation in biofuel cells.
- To compare direct electron transfer (DET) and mediated electron transfer (MET) bioanode architectures.
- To optimize bioanode materials and immobilization techniques for enhanced performance.
Main Methods:
- Enzyme immobilization on multi-walled carbon nanotubes (MWCNTs) and MWCNT-decorated gold nanoparticles.
- Testing of polymeric matrices (Nafion, polyethyleneimine, cellulose) for DET.
- Evaluation of ferrocene redox polymers for MET.
- Electrochemical characterization including cyclic voltammetry and chronoamperometry.
Main Results:
- Modified Nafion showed the best DET performance with catalytic currents of 16.8 ± 2.1 µA cm(-2).
- 1,1'-dimethylferrocene-modified linear polyethyleneimine (FcMe2-C3-LPEI) demonstrated superior MET performance.
- MET bioanodes with MWCNTs and MWCNTs-Au achieved maximum current densities (Jmax) of 781 ± 59 µA cm(-2) and 925 ± 68 µA cm(-2), respectively.
- DET showed limitations in achieving high current densities.
Conclusions:
- MET bioanodes employing ferrocene-modified LPEI exhibit significant potential for efficient energy conversion in ethanol/air biofuel cells.
- DET strategies require further development to enhance current densities for practical applications.
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