1
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Guberman-Pfeffer MJ. To be or not to be a cytochrome: electrical characterizations are inconsistent with Geobacter cytochrome 'nanowires'. Front Microbiol 2024; 15:1397124. [PMID: 38633696 PMCID: PMC11021709 DOI: 10.3389/fmicb.2024.1397124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 03/21/2024] [Indexed: 04/19/2024] Open
Abstract
Geobacter sulfurreducens profoundly shapes Earth's biogeochemistry by discharging respiratory electrons to minerals and other microbes through filaments of a two-decades-long debated identity. Cryogenic electron microscopy has revealed filaments of redox-active cytochromes, but the same filaments have exhibited hallmarks of organic metal-like conductivity under cytochrome denaturing/inhibiting conditions. Prior structure-based calculations and kinetic analyses on multi-heme proteins are synthesized herein to propose that a minimum of ~7 cytochrome 'nanowires' can carry the respiratory flux of a Geobacter cell, which is known to express somewhat more (≥20) filaments to increase the likelihood of productive contacts. By contrast, prior electrical and spectroscopic structural characterizations are argued to be physiologically irrelevant or physically implausible for the known cytochrome filaments because of experimental artifacts and sample impurities. This perspective clarifies our mechanistic understanding of physiological metal-microbe interactions and advances synthetic biology efforts to optimize those interactions for bioremediation and energy or chemical production.
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2
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Guberman-Pfeffer MJ. Assessing Thermal Response of Redox Conduction for Anti-Arrhenius Kinetics in a Microbial Cytochrome Nanowire. J Phys Chem B 2022; 126:10083-10097. [PMID: 36417757 PMCID: PMC9743091 DOI: 10.1021/acs.jpcb.2c06822] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A micrometers-long helical homopolymer of the outer-membrane cytochrome type S (OmcS) from Geobacter sulfurreducens is proposed to transport electrons to extracellular acceptors in an ancient respiratory strategy of biogeochemical and technological significance. OmcS surprisingly exhibits higher conductivity upon cooling (anti-Arrhenius kinetics), an effect previously attributed to H-bond restructuring and heme redox potential shifts. Herein, the temperature sensitivity of redox conductivity is more thoroughly examined with conventional and constant-redox and -pH molecular dynamics and quantum mechanics/molecular mechanics. A 30 K drop in temperature constituted a weak perturbation to electron transfer energetics, changing electronic couplings (⟨Hmn⟩), reaction free energies (ΔGmn), reorganization energies (λmn), and activation energies (Ea) by at most |0.002|, |0.050|, |0.120|, and |0.045| eV, respectively. Changes in ΔGmn reflected -0.07 ± 0.03 V shifts in redox potentials that were caused in roughly equal measure by altered electrostatic interactions with the solvent and protein. Changes in intraprotein H-bonding reproduced the earlier observations. Single-particle diffusion and multiparticle steady-state flux models, parametrized with Marcus theory rates, showed that biologically relevant incoherent hopping cannot qualitatively or quantitatively describe electrical conductivity measured by atomic force microscopy in filamentous OmcS. The discrepancy is attributed to differences between solution-phase simulations and solid-state measurements and the need to model intra- and intermolecular vibrations explicitly.
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Affiliation(s)
- Matthew J. Guberman-Pfeffer
- Department
of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar St., New Haven, Connecticut06510, United States,Microbial
Sciences Institute, Yale University, 840 West Campus Drive, West Haven, Connecticut06516, United States,
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3
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Lee HS, Xin W, Katakojwala R, Venkata Mohan S, Tabish NMD. Microbial electrolysis cells for the production of biohydrogen in dark fermentation - A review. BIORESOURCE TECHNOLOGY 2022; 363:127934. [PMID: 36100184 DOI: 10.1016/j.biortech.2022.127934] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 09/01/2022] [Accepted: 09/06/2022] [Indexed: 06/15/2023]
Abstract
To assess biohydrogen for future green energy, this review revisited dark fermentation and microbial electrolysis cells (MECs). Hydrogen evolution rate in mesophilic dark fermentation is as high as 192 m3 H2/m3-d, however hydrogen yield is limited. MECs are ideal for improving hydrogen yield from carboxylate accumulated from dark fermentation, whereas hydrogen production rate is too slow in MECs. Hence, improving anode kinetic is very important for realizing MEC biohydrogen. Intracellular electron transfer (IET) and extracellular electron transfer (EET) can limit current density in MECs, which is proportional to hydrogen evolution rate. EET does not limit current density once electrically conductive biofilms are formed on anodes, potentially producing 300 A/m2. Hence, IET kinetics mainly govern current density in MECs. Among parameters associated with IET kinetic, population of anode-respiring bacteria in anode biofilms, biofilm density of active microorganisms, biofilm thickness, and alkalinity are critical for current density.
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Affiliation(s)
- Hyung-Sool Lee
- KENTECH Institute for Environmental and Climate Technology, Korea Institute of Energy Technology (KENTECH) 200 Hyeoksin-ro, Naju-si, Jeollanam-do, Republic of Korea.
| | - Wang Xin
- MOE Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Ranaprathap Katakojwala
- Bioengineering and Environmental Engineering Lab, Department of Energy and Environmental Engineering, Indian Institute of Chemical Technology, Hyderabad 500007, India
| | - S Venkata Mohan
- Bioengineering and Environmental Engineering Lab, Department of Energy and Environmental Engineering, Indian Institute of Chemical Technology, Hyderabad 500007, India
| | - Noori M D Tabish
- Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcala, Alcala De Henares, Madrid 28801, Spain
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4
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McCuskey SR, Chatsirisupachai J, Zeglio E, Parlak O, Panoy P, Herland A, Bazan GC, Nguyen TQ. Current Progress of Interfacing Organic Semiconducting Materials with Bacteria. Chem Rev 2021; 122:4791-4825. [PMID: 34714064 DOI: 10.1021/acs.chemrev.1c00487] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microbial bioelectronics require interfacing microorganisms with electrodes. The resulting abiotic/biotic platforms provide the basis of a range of technologies, including energy conversion and diagnostic assays. Organic semiconductors (OSCs) provide a unique strategy to modulate the interfaces between microbial systems and external electrodes, thereby improving the performance of these incipient technologies. In this review, we explore recent progress in the field on how OSCs, and related materials capable of charge transport, are being used within the context of microbial systems, and more specifically bacteria. We begin by examining the electrochemical communication modes in bacteria and the biological basis for charge transport. Different types of synthetic organic materials that have been designed and synthesized for interfacing and interrogating bacteria are discussed next, followed by the most commonly used characterization techniques for evaluating transport in microbial, synthetic, and hybrid systems. A range of applications is subsequently examined, including biological sensors and energy conversion systems. The review concludes by summarizing what has been accomplished so far and suggests future design approaches for OSC bioelectronics materials and technologies that hybridize characteristic properties of microbial and OSC systems.
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Affiliation(s)
- Samantha R McCuskey
- Department of Chemistry, National University of Singapore, Singapore 119077, Singapore
| | - Jirat Chatsirisupachai
- Center for Polymers and Organic Solids & Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.,Department of Materials Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong 21210, Thailand
| | - Erica Zeglio
- Division of Micro and Nanosystems, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, Stockholm 17177, Sweden
| | - Onur Parlak
- Dermatology and Venereology Division, Department of Medicine(Solna), Karolinska Institute, Stockholm 17177, Sweden.,AIMES Center of Integrated Medical and Engineering Sciences, Department of Neuroscience, Karolinska Institute, Stockholm 17177, Sweden
| | - Patchareepond Panoy
- Center for Polymers and Organic Solids & Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.,Department of Materials Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong 21210, Thailand
| | - Anna Herland
- Division of Micro and Nanosystems, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, Stockholm 17177, Sweden.,AIMES Center of Integrated Medical and Engineering Sciences, Department of Neuroscience, Karolinska Institute, Stockholm 17177, Sweden
| | - Guillermo C Bazan
- Department of Chemistry, National University of Singapore, Singapore 119077, Singapore
| | - Thuc-Quyen Nguyen
- Center for Polymers and Organic Solids & Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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5
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Controls on Interspecies Electron Transport and Size Limitation of Anaerobically Methane-Oxidizing Microbial Consortia. mBio 2021; 12:mBio.03620-20. [PMID: 33975943 PMCID: PMC8263020 DOI: 10.1128/mbio.03620-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
About 382 Tg yr−1 of methane rising through the seafloor is oxidized anaerobically (W. S. Reeburgh, Chem Rev 107:486–513, 2007, https://doi.org/10.1021/cr050362v), preventing it from reaching the atmosphere, where it acts as a strong greenhouse gas. Microbial consortia composed of anaerobic methanotrophic archaea and sulfate-reducing bacteria couple the oxidation of methane to the reduction of sulfate under anaerobic conditions via a syntrophic process. Recent experimental studies and modeling efforts indicate that direct interspecies electron transfer (DIET) is involved in this syntrophy. Here, we explore a fluorescent in situ hybridization-nanoscale secondary ion mass spectrometry data set of large, segregated anaerobic oxidation of methane (AOM) consortia that reveal a decline in metabolic activity away from the archaeal-bacterial interface and use a process-based model to identify the physiological controls on rates of AOM. Simulations reproducing the observational data reveal that ohmic resistance and activation loss are the two main factors causing the declining metabolic activity, where activation loss dominated at a distance of <8 μm. These voltage losses limit the maximum spatial distance between syntrophic partners with model simulations, indicating that sulfate-reducing bacterial cells can remain metabolically active up to ∼30 μm away from the archaeal-bacterial interface. Model simulations further predict that a hybrid metabolism that combines DIET with a small contribution of diffusive exchange of electron donors can offer energetic advantages for syntrophic consortia.
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6
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Long-distance electron transfer in a filamentous Gram-positive bacterium. Nat Commun 2021; 12:1709. [PMID: 33731718 PMCID: PMC7969598 DOI: 10.1038/s41467-021-21709-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 02/05/2021] [Indexed: 01/31/2023] Open
Abstract
Long-distance extracellular electron transfer has been observed in Gram-negative bacteria and plays roles in both natural and engineering processes. The electron transfer can be mediated by conductive protein appendages (in short unicellular bacteria such as Geobacter species) or by conductive cell envelopes (in filamentous multicellular cable bacteria). Here we show that Lysinibacillus varians GY32, a filamentous unicellular Gram-positive bacterium, is capable of bidirectional extracellular electron transfer. In microbial fuel cells, L. varians can form centimetre-range conductive cellular networks and, when grown on graphite electrodes, the cells can reach a remarkable length of 1.08 mm. Atomic force microscopy and microelectrode analyses suggest that the conductivity is linked to pili-like protein appendages. Our results show that long-distance electron transfer is not limited to Gram-negative bacteria.
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7
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He X, Chadwick G, Jiménez Otero F, Orphan V, Meile C. Spatially Resolved Electron Transport through Anode‐Respiring
Geobacter sulfurreducens
Biofilms: Controls and Constraints. ChemElectroChem 2021. [DOI: 10.1002/celc.202100111] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Xiaojia He
- Department of Marine Sciences University of Georgia Athens GA USA
| | - Grayson Chadwick
- Division of Geological and Planetary Sciences California Institute of Technology Pasadena CA USA
| | | | - Victoria Orphan
- Division of Geological and Planetary Sciences California Institute of Technology Pasadena CA USA
| | - Christof Meile
- Department of Marine Sciences University of Georgia Athens GA USA
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8
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Cao DX, Yan H, Brus VV, Wong MS, Bazan GC, Nguyen TQ. Visualization of Charge Transfer from Bacteria to a Self-Doped Conjugated Polymer Electrode Surface Using Conductive Atomic Force Microscopy. ACS APPLIED MATERIALS & INTERFACES 2020; 12:40778-40785. [PMID: 32794728 DOI: 10.1021/acsami.0c10795] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this work, we aim to provide a better understanding of the reasons behind electron transfer inefficiencies between electrogenic bacteria and the electrode in microbial fuel cells. We do so using a self-doped conjugated polyelectrolyte (CPE) as the electrode surface, onto which Geobacter sulfurreducens is placed, then using conductive atomic force microscopy (C-AFM) to directly visualize and quantify the electrons that are transferring from each bacterium to the electrode, thereby helping us gain a better understanding for the overpotential losses in MFCs. In doing so, we obtain images that show G. sulfurreducens can directly transfer electrons to an electrode surface without the use of pili, and that overpotential losses are likely due to cell death and poor distribution or performance of individual bacterium's OmcB cytochromes. This unique combination of CPEs with C-AFM can also be used for other studies where electron transfer loss mechanisms need to be understood on the nanoscale, allowing for direct visualization of potential issues in these systems.
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Affiliation(s)
- David Xi Cao
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Hengjing Yan
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Viktor V Brus
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Matthew S Wong
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Guillermo C Bazan
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Thuc-Quyen Nguyen
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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9
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Roy S, Xie O, Dorval Courchesne N. Challenges in engineering conductive protein fibres: Disentangling the knowledge. CAN J CHEM ENG 2020. [DOI: 10.1002/cjce.23836] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Sophia Roy
- Department of Chemical Engineering McGill University Montréal Québec Canada
| | - Oliver Xie
- Department of Chemical Engineering McGill University Montréal Québec Canada
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10
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Caizán-Juanarena L, ter Heijne A, Weijma J, Yntema D, Suárez-Zuluaga DA, Buisman CJ. Screening for electrical conductivity in anaerobic granular sludge from full-scale wastewater treatment reactors. Biochem Eng J 2020. [DOI: 10.1016/j.bej.2020.107575] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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11
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Ru X, Zhang P, Beratan DN. Assessing Possible Mechanisms of Micrometer-Scale Electron Transfer in Heme-Free Geobacter sulfurreducens Pili. J Phys Chem B 2019; 123:5035-5047. [PMID: 31095388 DOI: 10.1021/acs.jpcb.9b01086] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The electrically conductive pili of Geobacter sulfurreducens are of both fundamental and practical interest. They facilitate extracellular and interspecies electron transfer (ET) and also provide an electrical interface between living and nonliving systems. We examine the possible mechanisms of G. sulfurreducens electron transfer in regimes ranging from incoherent to coherent transport. For plausible ET parameters, electron transfer in G. sulfurreducens bacterial nanowires mediated only by the protein is predicted to be dominated by incoherent hopping between phenylalanine (Phe) and tyrosine (Tyr) residues that are 3 to 4 Å apart, where Phe residues in the hopping pathways may create delocalized "islands." This mechanism could be accessible in the presence of strong oxidants that are capable of oxidizing Phe and Tyr residues. We also examine the physical requirements needed to sustain biological respiration via nanowires. We find that the hopping regimes with ET rates on the order of 108 s-1 between Phe islands and Tyr residues, and conductivities on the order of mS/cm, can support ET fluxes that are compatible with cellular respiration rates, although sustaining this delocalization in the heterogeneous protein environment may be challenging. Computed values of fully coherent electron fluxes through the pili are orders of magnitude too low to support microbial respiration. We suggest experimental probes of the transport mechanism based on mutant studies to examine the roles of aromatic amino acids and yet to be identified redox cofactors.
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Affiliation(s)
- Xuyan Ru
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - Peng Zhang
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - David N Beratan
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States.,Department of Biochemistry , Duke University , Durham , North Carolina 27710 , United States.,Department of Physics , Duke University , Durham , North Carolina 27708 , United States
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12
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Wang Q, Jones AAD, Gralnick JA, Lin L, Buie CR. Microfluidic dielectrophoresis illuminates the relationship between microbial cell envelope polarizability and electrochemical activity. SCIENCE ADVANCES 2019; 5:eaat5664. [PMID: 30746438 PMCID: PMC6357865 DOI: 10.1126/sciadv.aat5664] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 11/30/2018] [Indexed: 05/28/2023]
Abstract
Electrons can be transported from microbes to external insoluble electron acceptors (e.g., metal oxides or electrodes in an electrochemical cell). This process is known as extracellular electron transfer (EET) and has received considerable attention due to its applications in environmental remediation and energy conversion. However, the paucity of rapid and noninvasive phenotyping techniques hinders a detailed understanding of microbial EET mechanisms. Most EET phenotyping techniques assess microorganisms based on their metabolism and growth in various conditions and/or performance in electrochemical systems, which requires large sample volumes and cumbersome experimentation. Here, we use microfluidic dielectrophoresis to show a strong correlation between bacterial EET and surface polarizability. We analyzed surface polarizabilities for wild-type strains and cytochrome-deletion mutants of two model EET microbes, Geobacter sulfurreducens and Shewanella oneidensis, and for Escherichia coli strains heterologously expressing S. oneidensis EET pathways in various growth conditions. Dielectrophoretic phenotyping is achieved with small cell culture volumes (~100 μl) in a short amount of time (1 to 2 min per strain). Our work demonstrates that cell polarizability is diminished in response to deletions of crucial outer-membrane cytochromes and enhanced due to additions of EET pathways. Results of this work hold exciting promise for rapid screening of direct EET or other cell envelope phenotypes using cell polarizability as a proxy, especially for microbes difficult to cultivate in laboratory conditions.
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Affiliation(s)
- Qianru Wang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - A.-Andrew D. Jones
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Jeffrey A. Gralnick
- Department of Plant and Microbial Biology, BioTechnology Institute, University of Minnesota Twin Cities, 1479 Gortner Avenue, St. Paul, MN 55108, USA
| | - Liwei Lin
- Department of Mechanical Engineering, University of California, Berkeley, 1113 Etcheverry Hall #1740, Berkeley, CA 94720-1740, USA
| | - Cullen R. Buie
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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13
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Electron transfer and transport through multi-heme proteins: recent progress and future directions. Curr Opin Chem Biol 2018; 47:24-31. [DOI: 10.1016/j.cbpa.2018.06.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 06/24/2018] [Indexed: 12/20/2022]
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14
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Golden J, Yates MD, Halsted M, Tender L. Application of electrochemical surface plasmon resonance (ESPR) to the study of electroactive microbial biofilms. Phys Chem Chem Phys 2018; 20:25648-25656. [PMID: 30289415 DOI: 10.1039/c8cp03898h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Electrochemical surface plasmon resonance (ESPR) monitors faradaic processes optically by the change in refractive index that occurs with a change in redox state at the electrode surface. Here we apply ESPR to investigate the anode-grown Geobacter sulfurreducens biofilm (GSB), a model system used to study electroactive microbial biofilms (EABFs) which perform electrochemical reactions using electrodes as metabolic electron acceptors or donors. A substantial body of evidence indicates that electron transfer reactions among hemes of c-type cytochromes (c-Cyt) play major roles in the extracellular electron transfer (EET) pathways that connect intracellular metabolic processes of cells in an EABF to the electrode surface. The results reported here reveal that when the potential of the electrode is changed from relatively oxidizing (0.40 V vs. SHE) to reducing (-0.55 V vs. SHE) and then back to oxidizing, 70% of c-Cyt residing closest to the biofilm/electrode (within hundreds of nm from the electrode surface) appear to remain trapped in the reduced state, requiring as long as 12 hours to be re-oxidized. c-Cyt storing electrons cannot contribute to EET, yet turnover current resulting from cellular oxidation of acetate coupled with EET to the electrode surface is unaffected. This suggests that a relatively small fraction of c-Cyt residing closest to the biofilm/electrode interface is involved in EET while the majority store electrons. The results also reveal that biomass density at the biofilm/electrode interface increases rapidly during lag phase, reaching its maximum value at the onset of exponential biofilm growth when turnover current begins to rapidly increase.
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Affiliation(s)
- Joel Golden
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington DC, 20375, USA.
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15
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Enhanced redox conductivity and enriched Geobacteraceae of exoelectrogenic biofilms in response to static magnetic field. Appl Microbiol Biotechnol 2018; 102:7611-7621. [DOI: 10.1007/s00253-018-9158-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 05/01/2018] [Accepted: 06/05/2018] [Indexed: 12/26/2022]
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16
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Yates MD, Barr Engel S, Eddie BJ, Lebedev N, Malanoski AP, Tender LM. Redox-gradient driven electron transport in a mixed community anodic biofilm. FEMS Microbiol Ecol 2018; 94:4990946. [DOI: 10.1093/femsec/fiy081] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 05/01/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- Matthew D Yates
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC, 20375, USA
| | - Sarah Barr Engel
- Department of Civil and Environmental Engineering, Cornell University, 220 Hollister Hall, Ithaca, NY, 14853, USA
| | - Brian J Eddie
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC, 20375, USA
| | - Nikolai Lebedev
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC, 20375, USA
| | - Anthony P Malanoski
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC, 20375, USA
| | - Leonard M Tender
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC, 20375, USA
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17
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Lee HS. Electrokinetic analyses in biofilm anodes: Ohmic conduction of extracellular electron transfer. BIORESOURCE TECHNOLOGY 2018; 256:509-514. [PMID: 29478785 DOI: 10.1016/j.biortech.2018.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 06/08/2023]
Abstract
This review explores electron transfer kinetics from an electron donor to the anode in electrically conductive biofilm anodes. Intracellular electron transfer (IET) from the donor to the anode is well described with the Monod equation. In comparison, mechanisms of extracellular electron transfer (EET) conduction are unclear yet, complicating EET kinetics. However, in biofilm anodes where potential gradient to saturated current density is less than ∼300 mV, Ohmic conduction successfully describe conductive EET mainly with biofilm conductivity (Kbio) and biofilm thickness (Lf). High Kbio essential for production of high current density is found in Geobacter pure or enriched biofilm anodes, but other exoelectrogens could make biofilms electrically conductive. IET is rate-limiting for current density in conductive biofilms, and biofilm density of active exoelectrogens and Lf are operating parameters that can be optimized further to improve current density.
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Affiliation(s)
- Hyung-Sool Lee
- Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West Waterloo, Ontario N2L 3G, Canada.
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18
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Microbial nanowires - Electron transport and the role of synthetic analogues. Acta Biomater 2018; 69:1-30. [PMID: 29357319 DOI: 10.1016/j.actbio.2018.01.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 01/07/2018] [Accepted: 01/09/2018] [Indexed: 02/07/2023]
Abstract
Electron transfer is central to cellular life, from photosynthesis to respiration. In the case of anaerobic respiration, some microbes have extracellular appendages that can be utilised to transport electrons over great distances. Two model organisms heavily studied in this arena are Shewanella oneidensis and Geobacter sulfurreducens. There is some debate over how, in particular, the Geobacter sulfurreducens nanowires (formed from pilin nanofilaments) are capable of achieving the impressive feats of natural conductivity that they display. In this article, we outline the mechanisms of electron transfer through delocalised electron transport, quantum tunnelling, and hopping as they pertain to biomaterials. These are described along with existing examples of the different types of conductivity observed in natural systems such as DNA and proteins in order to provide context for understanding the complexities involved in studying the electron transport properties of these unique nanowires. We then introduce some synthetic analogues, made using peptides, which may assist in resolving this debate. Microbial nanowires and the synthetic analogues thereof are of particular interest, not just for biogeochemistry, but also for the exciting potential bioelectronic and clinical applications as covered in the final section of the review. STATEMENT OF SIGNIFICANCE Some microbes have extracellular appendages that transport electrons over vast distances in order to respire, such as the dissimilatory metal-reducing bacteria Geobacter sulfurreducens. There is significant debate over how G. sulfurreducens nanowires are capable of achieving the impressive feats of natural conductivity that they display: This mechanism is a fundamental scientific challenge, with important environmental and technological implications. Through outlining the techniques and outcomes of investigations into the mechanisms of such protein-based nanofibrils, we provide a platform for the general study of the electronic properties of biomaterials. The implications are broad-reaching, with fundamental investigations into electron transfer processes in natural and biomimetic materials underway. From these studies, applications in the medical, energy, and IT industries can be developed utilising bioelectronics.
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19
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Li C, Lesnik KL, Liu H. Conductive properties of methanogenic biofilms. Bioelectrochemistry 2018; 119:220-226. [DOI: 10.1016/j.bioelechem.2017.10.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 10/17/2017] [Accepted: 10/17/2017] [Indexed: 01/06/2023]
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20
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Yates MD, Eddie BJ, Lebedev N, Kotloski NJ, Strycharz-Glaven SM, Tender LM. On the relationship between long-distance and heterogeneous electron transfer in electrode-grown Geobacter sulfurreducens biofilms. Bioelectrochemistry 2018; 119:111-118. [DOI: 10.1016/j.bioelechem.2017.09.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 09/12/2017] [Accepted: 09/14/2017] [Indexed: 02/05/2023]
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21
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Grebenko A, Dremov V, Barzilovich P, Bubis A, Sidoruk K, Voeikova T, Gagkaeva Z, Chernov T, Korostylev E, Gorshunov B, Motovilov K. Impedance spectroscopy of single bacterial nanofilament reveals water-mediated charge transfer. PLoS One 2018; 13:e0191289. [PMID: 29351332 PMCID: PMC5774759 DOI: 10.1371/journal.pone.0191289] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 01/02/2018] [Indexed: 11/19/2022] Open
Abstract
For decades respiratory chain and photosystems were the main firing field of the studies devoted to mechanisms of electron transfer in proteins. The concept of conjugated lateral electron and transverse proton transport during cellular respiration and photosynthesis, which was formulated in the beginning of 1960-s, has been confirmed by thousands of experiments. However, charge transfer in recently discovered bacterial nanofilaments produced by various electrogenic bacteria is regarded currently outside of electron and proton conjugation concept. Here we report the new study of charge transfer within nanofilaments produced by Shewanella oneidensis MR-1 conducted in atmosphere of different relative humidity (RH). We utilize impedance spectroscopy and DC (direct current) transport measurements to find out the peculiarities of conductivity and Raman spectroscopy to analyze the nanofilaments' composition. Data analysis demonstrates that apparent conductivity of nanofilaments has crucial sensitivity to humidity and contains several components including one with unusual behavior which we assign to electron transport. We demonstrate that in the case of Shewanella oneidensis MR-1 charge transfer within these objects is strongly mediated by water. Basing on current data analysis of conductivity we conclude that the studied filaments of Shewanella oneidensis MR-1 are capable of hybrid (conjugated) electron and ion conductivity.
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Affiliation(s)
- Artem Grebenko
- Moscow Institute of Physics and Technology, Institute lane 9, Dolgoprudny, Russian Federation
- Institute of Solid State Physics (RAS), Academician Osipyana street 2, Chernogolovka, Russia
| | - Vyacheslav Dremov
- Moscow Institute of Physics and Technology, Institute lane 9, Dolgoprudny, Russian Federation
- Institute of Solid State Physics (RAS), Academician Osipyana street 2, Chernogolovka, Russia
| | - Petr Barzilovich
- Moscow Institute of Physics and Technology, Institute lane 9, Dolgoprudny, Russian Federation
- Institute of Problems of Chemical Physics (RAS), Academician Semenov avenue 1, Chernogolovka, Russia
| | - Anton Bubis
- Moscow Institute of Physics and Technology, Institute lane 9, Dolgoprudny, Russian Federation
- Institute of Solid State Physics (RAS), Academician Osipyana street 2, Chernogolovka, Russia
| | - Konstantin Sidoruk
- Scientific Center of Russian Federation Research Institute for Genetics and Selection of Industrial Microorganisms, 1-st Dorozhniy pr., 1, Moscow, Russia
| | - Tatiyana Voeikova
- Scientific Center of Russian Federation Research Institute for Genetics and Selection of Industrial Microorganisms, 1-st Dorozhniy pr., 1, Moscow, Russia
| | - Zarina Gagkaeva
- Moscow Institute of Physics and Technology, Institute lane 9, Dolgoprudny, Russian Federation
| | - Timur Chernov
- Moscow Institute of Physics and Technology, Institute lane 9, Dolgoprudny, Russian Federation
- Institute of Problems of Chemical Physics (RAS), Academician Semenov avenue 1, Chernogolovka, Russia
| | - Evgeny Korostylev
- Moscow Institute of Physics and Technology, Institute lane 9, Dolgoprudny, Russian Federation
| | - Boris Gorshunov
- Moscow Institute of Physics and Technology, Institute lane 9, Dolgoprudny, Russian Federation
| | - Konstantin Motovilov
- Moscow Institute of Physics and Technology, Institute lane 9, Dolgoprudny, Russian Federation
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22
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Dhar BR, Sim J, Ryu H, Ren H, Santo Domingo JW, Chae J, Lee HS. Microbial activity influences electrical conductivity of biofilm anode. WATER RESEARCH 2017; 127:230-238. [PMID: 29055828 PMCID: PMC7321815 DOI: 10.1016/j.watres.2017.10.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 10/11/2017] [Accepted: 10/12/2017] [Indexed: 05/14/2023]
Abstract
This study assessed the conductivity of a Geobacter-enriched biofilm anode in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH gradient across the biofilm anode at 100 mM phosphate buffer (current density 2.38 A/m2) and biofilm conductivity (Kbio) was as high as 0.87 mS/cm. In comparison, an inner biofilm became acidic at 2.5 mM phosphate buffer in which dead cells were accumulated at ∼80 μm of the inner biofilm anode. At this low phosphate buffer, Kbio significantly decreased by 0.27 mS/cm, together with declined current density of 0.64 A/m2. This work demonstrates that biofilm conductivity depends on the composition of live and dead cells in the conductive biofilm anode.
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Affiliation(s)
- Bipro Ranjan Dhar
- Civil and Environmental Engineering, University of Alberta, 9211-116 Street NW, Edmonton, Alberta, T6G 1H9, Canada; Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada.
| | - Junyoung Sim
- Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada.
| | - Hodon Ryu
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Hao Ren
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA.
| | - Jorge W Santo Domingo
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Junseok Chae
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA.
| | - Hyung-Sool Lee
- Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada.
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23
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Abstract
Microbial electrochemistry has from the onset been recognized for its sensing potential due to the microbial ability to enhance signals through metabolic cascades, its relative selectivity toward substrates, and the higher stability conferred by the microbial ability to self-replicate. The greatest challenge has been to achieve stable and efficient transduction between a microorganism and an electrode surface. Over the past decades, a new kind of microbial architecture has been observed to spontaneously develop on polarized electrodes: the electroactive biofilm (EAB). The EAB conducts electrons over long distances and performs quasi-reversible electron transfer on conventional electrode surfaces. It also possesses self-regenerative properties. In only a few years, EABs have inspired considerable research interest for use as biosensors for environmental or bioprocess monitoring. Multiple challenges still need to be overcome before implementation at larger scale of this new kind of biosensors can be realized. This perspective first introduces the specific characteristics of the EAB with respect to other electrochemical biosensors. It summarizes the sensing applications currently proposed for EABs, stresses their limitations, and suggests strategies toward potential solutions. Conceptual prospects to engineer EABs for sensing purposes are also discussed.
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Affiliation(s)
- Antonin Prévoteau
- Center for Microbial Ecology
and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Korneel Rabaey
- Center for Microbial Ecology
and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
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24
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Li C, Lesnik KL, Liu H. Stay connected: Electrical conductivity of microbial aggregates. Biotechnol Adv 2017; 35:669-680. [PMID: 28768145 DOI: 10.1016/j.biotechadv.2017.07.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 07/25/2017] [Accepted: 07/27/2017] [Indexed: 01/01/2023]
Abstract
The discovery of direct extracellular electron transfer offers an alternative to the traditional understanding of diffusional electron exchange via small molecules. The establishment of electronic connections between electron donors and acceptors in microbial communities is critical to electron transfer via electrical currents. These connections are facilitated through conductivity associated with various microbial aggregates. However, examination of conductivity in microbial samples is still in its relative infancy and conceptual models in terms of conductive mechanisms are still being developed and debated. The present review summarizes the fundamental understanding of electrical conductivity in microbial aggregates (e.g. biofilms, granules, consortia, and multicellular filaments) highlighting recent findings and key discoveries. A greater understanding of electrical conductivity in microbial aggregates could facilitate the survey for additional microbial communities that rely on direct extracellular electron transfer for survival, inform rational design towards the aggregates-based production of bioenergy/bioproducts, and inspire the construction of new synthetic conductive polymers.
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Affiliation(s)
- Cheng Li
- Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97333, USA
| | - Keaton Larson Lesnik
- Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97333, USA
| | - Hong Liu
- Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97333, USA.
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25
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Abstract
Descriptions of the changeable, striking colors associated with secreted natural products date back well over a century. These molecules can serve as extracellular electron shuttles (EESs) that permit microbes to access substrates at a distance. In this review, we argue that the colorful world of EESs has been too long neglected. Rather than simply serving as a diagnostic attribute of a particular microbial strain, redox-active natural products likely play fundamental, underappreciated roles in the biology of their producers, particularly those that inhabit biofilms. Here, we describe the chemical diversity and potential distribution of EES producers and users, discuss the costs associated with their biosynthesis, and critically evaluate strategies for their economical usage. We hope this review will inspire efforts to identify and explore the importance of EES cycling by a wide range of microorganisms so that their contributions to shaping microbial communities can be better assessed and exploited.
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Affiliation(s)
- Nathaniel R Glasser
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125; , ,
| | - Scott H Saunders
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125; , ,
| | - Dianne K Newman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125; , , .,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125
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26
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Zhang X, Philips J, Roume H, Guo K, Rabaey K, Prévoteau A. Rapid and Quantitative Assessment of Redox Conduction Across Electroactive Biofilms by using Double Potential Step Chronoamperometry. ChemElectroChem 2017. [DOI: 10.1002/celc.201600853] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Xu Zhang
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
| | - Jo Philips
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
| | - Hugo Roume
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
- MetaGenoPolis; INRA; Université Paris-Saclay Domaine de Vilvert; Bâtiment 325 78350 Jouy-en-Josas France
| | - Kun Guo
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
| | - Korneel Rabaey
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
| | - Antonin Prévoteau
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
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27
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Cytochrome OmcZ is essential for the current generation by Geobacter sulfurreducens under low electrode potential. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.01.091] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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28
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Dhar BR, Ryu H, Ren H, Domingo JWS, Chae J, Lee HS. High Biofilm Conductivity Maintained Despite Anode Potential Changes in a Geobacter-Enriched Biofilm. CHEMSUSCHEM 2016; 9:3485-3491. [PMID: 27870324 PMCID: PMC7377214 DOI: 10.1002/cssc.201601007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/25/2016] [Indexed: 05/25/2023]
Abstract
This study systematically assessed intracellular electron transfer (IET) and extracellular electron transfer (EET) kinetics with respect to anode potential (Eanode ) in a mixed-culture biofilm anode enriched with Geobacter spp. High biofilm conductivity (0.96-1.24 mS cm-1 ) was maintained during Eanode changes from -0.2 to +0.2 V versus the standard hydrogen electrode (SHE), although the steady-state current density significantly decreased from 2.05 to 0.35 A m-2 in a microbial electrochemical cell. Substantial increase of the Treponema population was observed in the biofilm anode at Eanode =+0.2 V, which reduced intracellular electron-transfer kinetics associated with the maximum specific substrate-utilization rate by a factor of ten. This result suggests that fast EET kinetics can be maintained under dynamic Eanode conditions in a highly conductive biofilm anode as a result of shift of main EET players in the biofilm anode, although Eanode changes can influence IET kinetics.
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Affiliation(s)
- Bipro Ranjan Dhar
- Civil and Environmental Engineering, University of Alberta, 9211-116 Street NW, Edmonton, Alberta, T6G 1H9, Canada
| | - Hodon Ryu
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH, 45268, USA
| | - Hao Ren
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA
| | - Jorge W Santo Domingo
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH, 45268, USA
| | - Junkseck Chae
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA
| | - Hyung-Sool Lee
- Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada
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29
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Yates MD, Strycharz-Glaven SM, Golden JP, Roy J, Tsoi S, Erickson JS, El-Naggar MY, Barton SC, Tender LM. Measuring conductivity of living Geobacter sulfurreducens biofilms. NATURE NANOTECHNOLOGY 2016; 11:910-913. [PMID: 27821847 DOI: 10.1038/nnano.2016.186] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Affiliation(s)
- Matthew D Yates
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington DC 20375, USA
- National Research Council, Washington DC 20418, USA
| | - Sarah M Strycharz-Glaven
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington DC 20375, USA
| | - Joel P Golden
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington DC 20375, USA
| | - Jared Roy
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington DC 20375, USA
- George Mason University, Fairfax, Virginia 22030, USA
| | - Stanislav Tsoi
- Chemistry Division, Naval Research Laboratory, Washington DC 20375, USA
| | - Jeffrey S Erickson
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington DC 20375, USA
| | - Mohamed Y El-Naggar
- Departments of Physics, Biological Sciences, and Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Scott Calabrese Barton
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA
| | - Leonard M Tender
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington DC 20375, USA
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