BioFiles Volume 5, Number 5 — Enzymes and Reagents for Alternative Energy

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Advancements in Enzyme-Based Fuel Cell Batteries, Sensors and Emissions Reduction Strategies

Dr. Shelley Minteer, Ph.D.
Dr. Shelley
Minteer, Ph.D.

Sigma Life Science® and Aldrich® Materials Science merge to help researchers completely rethink tomorrow's immobilized enzyme technologies.

Today's fuel cells and batteries lack the ability to produce electrical power for the long periods of time we desire and commonly incorporate toxic or precious metals to produce and store their energy.

Enzyme-based fuel cells have potentially higher energy density than traditional batteries using much more environmentally compatible materials. While the idea of enzyme-based biofuel cells is not a new concept, recent developments have captured the interests of the research community. Dr. Shelley Minteer at Saint Louis University Department of Chemistry is one of the pioneers in this area. Dr. Minteer and her team have developed a new enzyme immobilization technology that has begun to revolutionize the way we think about using enzymes for long-term catalytic applications.

Dr. Minteer's enzyme immobilization strategy encapsulates and stabilizes Sigma® enzymes in modified Nafion® polymer matrices from Aldrich. The efficacy of Dr. Minteer's immobilized enzymes can be measured in years compared to days for other biofuel cell technologies. Dr. Minteer has successfully demonstrated the use of several metabolic fuels such as glycerol, fatty acids, ethanol and other alcohols, pyruvate and glucose to provide the fuel source, while a wide variety of enzymes and coupled multienzyme systems provide the catalytic power to convert the fuel to electrical current.

In addition to synthetic polymer supports, Dr. Minteer and her collaborator, Dr. Michael Cooney of the University of Hawaii, have immobilized dehydrogenases on macroporous chitosan scaffolds. The scaffolds were fabricated from solutions of native and hydrophobically modified chitosan polymers through the process of thermally induced phase separation. The hydrophobically modified chitosan is proposed to possess amphiphilic micelles into which the enzyme can be encapsulated and retained.

One of Dr. Minteer's basic biofuel cell batteries employs an ethanol/alcohol dehydrogenase system to generate a proton gradient across the conductive membrane. They have also refined these dehydrogenase systems by replacing traditional NAD(H) cofactor-dependent dehydrogenases with pyrroloquinoline quinone(PQQ)-dependent dehydrogenases to improve efficiency. Other multienzyme coupled systems use classical glycolytic and Krebs cycle enzyme systems and corresponding metabolic substrates to generate power.

Dr. Minteer's lab has also utilized mitochondria to generate current by metabolism of classic cellular energy sources. The resulting electrons are shuffled through the electron transport chain where they reduce oxygen at cytochrome c oxidase and combine with the protons from oxidation to form water. During this metabolic process it is possible for cytochrome c to undergo direct electron transfer to a carbon electrode and complete oxygen reduction at a platinum cathode.

Taking advantage of the fact that nitroaromatics can decouple the inhibition of pyruvate metabolism, mitochondriamodified electrodes have also been used to electrochemically sense the presence of nitroaromatic explosive compounds. These oligomycin inhibited mitochondria-modified electrodes were employed as the bioanode in a pyruvate/air biofuel cell. This concept could be used as a traditional electrochemical sensor or as a self-powered sensor.

Dr. Minteer's Nafion-based immobilization technology is also addressing the reduction of fluegas emissions from coal-fired power plants using carbonic anhydrase to sequester CO2.

 

Enzymes immobilized in Nafion® membrane are encapsulated in the polymer resulting in increased stability while retaining active site availability and optimized orientation.




An an example of one of Dr Minteer's fuel cells; utilizing pyruvate as the initial fuel source, this fuel cell incorporates a multi-enzyme coupled system that generates a proton gradient source of energy analogous to that produced in vivo in the Kreb's Cycle.

References

  1. S.D. Minteer, B.Y. Liaw, and M.J. Cooney, "Enzyme-based biofuel cells," Current Opinions in Biotechnology, 2007, 18, 228–234.
  2. C.M. Moore, N.L. Akers, and S.D. Minteer, "Improving the Environment for Immobilized Dehydrogenase Enzymes by Modifying Nafion with Tetraalkylammonium Bromides," Biomacromolecules, 5, 2004, 1241–1247.
  3. M.J. Cooney, M. Windmeisser, B.Y. Liaw, C. Lau, T. Klotzbach, and S.D. Minteer, "Design of Chitosan Gel Pore Structure: Towards Enzyme Catalyzed Flow-Through Electrodes," Journal of Materials Chemistry, 2008, 18, 667–674.
  4. P. Atanassov, C. Apblett, S. Banta, S. Brozik, S. Calabrese Barton, M. Cooney, B.Y. Liaw, S. Mukerjee, and S.D. Minteer, "Enzymatic Biofuel Cells," Electrochemical Society Interface, 16, 2007, 28–31.
  5. T.L. Klotzbach, M. Watt, Y. Ansari, and S.D. Minteer, "Improving the microenvironment for enzyme immobilization at electrodes by hydrophobically modifying chitosan and Nafion polymers," Journal of Membrane Science, 2008, 311, 81–88.
  6. V. Svoboda, M. Cooney, B.Y. Liaw, S. Minteer, E. Piles, D. Lehnert, S.C. Barton, R. Rincon, and P. Atanassov, "Standardized characterization of biocatalytic electrodes," Electroanalysis, 2008, 20, 1099–1109.
  7. B.L. Treu, R. Arechederra, and S.D. Minteer, "Bioelectrocatalysis of Ethanol via PQQ-Dependent Dehydrogenases Utilizing Carbon Nanomaterial Supports," Journal of Nanoscience and Nanotechnology, 2009, 9, 2374–2380.
  8. B.L. Treu and S.D. Minteer, "Isolation and Purification of PQQ-dependent Lactate Dehydrogenase from Gluconobacter and Use for Direct Electron Transfer at Carbon and Gold Electrodes," Bioelectrochemistry, 2008, 74, 71–77.
  9. D. Sokic-Lazic and S.D. Minteer, "Citric acid cycle biomimic on a carbon electrode," Biosensors and Bioelectronics, 2008, 24, 945–950.
  10. A.E. Blackwell, M.J. Moehlenbrock, J.R. Worsham, and S.D. Minteer, "Comparison of Electropolymerized Thiazine Dyes as an Electrocatalyst in Enzymatic Biofuel Cells and Self Powered Sensors," Journal of Nanoscience and Nanotechnology, 2009, 9, 1719–1726.
  11. M. Cooney, V. Svoboda, C. Lau, G. Martin, and S.D. Minteer, "Enzymatic Biofuel Cells," Energy and Environmental Science, 2008, 1, 320–337.
  12. M.J. Cooney, J. Petermann, C. Lau, S.D. Minteer, "Characterization and Evaluation of Hydrophobically Modified Chitosan Scaffolds: towards design of enzyme immobilized flow-through electrodes," Carbohydrate Polymers, 2009, 75, 428–435.
  13. G. Martin, S. Minteer, and M.J. Cooney, "Spatial distribution of malate dehydrogenase in amphiphilic chitosan scaffolds," Applied Materials and Interfaces, 2009, 1(2) 367–372.
  14. C. Hettige, S.D. Minteer, and S. Calabrese Barton, "Simulation of Multi-Step Enzyme Electrodes," ECS Transactions, 2008, 13/21, 99–109.
  15. K. Sjoholm, M.J. Cooney, and S.D. Minteer, "Effects of Degree of Deacetylation on Enzyme Immobilization in Hydrophobically Modified Chitosan," Carbohydrate Polymers, 2009, 77, 420–424.
  16. G. Martin, S.D. Minteer, and M.J. Cooney, "Fluorescence characterization of chemical microenvironments in hydrophobically modified chitosan," Carbohydrate Polymers, 2009, 77, 695–702.
  17. D. Sokic-Lazic and S.D. Minteer, "Pyruvate/air enzymatic biofuel cell capable of complete oxidation," Electrochemical and Solid-State Letters, 2009, 12(9), F26–F28.
  18. M.C. Beilke, T.L. Klotzbach, B.L. Treu, D. Sokic-Lazic, J. Wildrick, E.R. Amend, L.M. Gebhart, R.L. Arechederra, M.N. Germain, M.J. Moehlenbrock, Sudhanshu, and S.D. Minteer, "Enzymatic Biofuel Cells," in Micro-Fuel Cells: Principles and Applications, Elsevier, 2009, 179–241.
  19. M. J. Moehlenbrock, R. L. Arechederra, K. H. Sjoholm, and S.D. Minteer, "Analytical Techniques for Characterizing Enzymatic Biofuel Cells," Analytical Chemistry, 2009, 81(23), 9538–9545.
  20. P. Addo, R. Arechederra, and S. D. Minteer, "Evaluating Enzyme Cascades for Methanol/Air Biofuel Cells Based on NAD-dependent Enzymes," Electroanalysis, 2010, 22(7-8), 807–812.
  21. R. Rincoln, M. Germain, K. Artyushkova, M. Mojica, M. Germaine, P. Atanassov, and S.D. Minteer, "Structure and Electrochemical Properties of Electrocatalysts for NADH Oxidation," Electroanalysis, 2010, 22(7–8), 799–806.
  22. W. Gellett, M. Kesmez, J. Schumacher, N. Akers, and S.D. Minteer, "Biofuel Cells for Portable Power," Electroanalysis, 2010, 22(7–8), 727–731.
  23. D. Sokic-Lazic, R.L. Arechederra, B.L. Treu, and S.D. Minteer, "Oxidation of Biofuels: Fuel Diversity and Effectiveness of Fuel Oxidation through Multiple Enzyme Cascades," Electroanalysis, 2010, 22(7–8), 757–764.
  24. C. Lau, G. Martin, S.D. Minteer, and M.J. Cooney, "Development of a Chitosan Scaffold Electrode for Fuel Cell Applications," Electroanalysis, 2010, 22(7–8), 793–798.
  25. R. Arechederra, B.L. Treu, and S.D. Minteer, "Development of Glycerol/Oxygen Biofuel Cells," Journal of Power Sources, 173, 2007, 156–161.
  26. R. Arechederra and S.D. Minteer, "Organelle-Based Biofuel Cells: Immobilized Mitochondria at Carbon Paper Electrodes," Electrochimica Acta, 2008, 53, 6698–6703.
  27. M. Germain, R. Arechederra, and S.D. Minteer, "Nitroaromatic Actuation of Mitochondrial Bioelectrocatalysis for Self Powered Explosive Sensors," Journal of the American Chemical Society, 2008, 130(46), 15272–15273.
  28. R. Arechederra, K. Boehm, and S.D. Minteer, "Mitochondrial Bioelectrocatalysis for Biofuel Cell Applications," Electrochimica Acta, 2009, 54, 7268–7273.

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