Co-reporter:Maria José González-Guerrero, F. Javier del Campo, Juan Pablo Esquivel, Dónal Leech, Neus Sabaté
Biosensors and Bioelectronics 2017 Volume 90(Volume 90) pp:
Publication Date(Web):15 April 2017
DOI:10.1016/j.bios.2016.09.062
•A compact paper-based biofuel cell that can be operated using a very limited sample volume is presented.•The system explores the energy generated by glucose at concentrations within physiological range.•The paper-based fuel cell has the potential of generating energy to power small biodevices.This work addresses the development of a compact paper-based enzymatic microfluidic glucose/O2 fuel cell that can operate using a very limited sample volume (≈35 µl) and explores the energy generated by glucose at concentrations typically found in blood samples at physiological conditions (pH 7.4). Carbon paper electrodes combined with a paper sample absorption substrate all contained within a plastic microfluidic casing are used to construct the paper-based fuel cell. The anode catalysts consist of glucose dehydrogenase and [Os(4,4′-dimethoxy-2,2′-bipyridine)2(poly-vinylimidazole)10Cl]+ as mediator, while the cathode catalysts were bilirubin oxidase and [Os(2,2′-bipyridine)2(poly-vinylimidazole)10Cl]+ as mediator.The fuel cell delivered a linear power output response to glucose over the range of 2.5–30 mM, with power densities ranging from 20 to 90 µW cm−2. The quantification of the available electrical power as well as the energy density extracted from small synthetic samples allows planning potential uses of this energy to power different sensors and analysis devices in a wide variety of in-vitro applications.Download high-res image (288KB)Download full-size image
Co-reporter:Peter Ó Conghaile, Magnus Falk, Domhnall MacAodha, Maria E. Yakovleva, Christoph Gonaus, Clemens K. Peterbauer, Lo Gorton, Sergey Shleev, and Dónal Leech
Analytical Chemistry 2016 Volume 88(Issue 4) pp:2156
Publication Date(Web):January 11, 2016
DOI:10.1021/acs.analchem.5b03745
Coimmobilization of pyranose dehydrogenase as an enzyme catalyst, osmium redox polymers [Os(4,4′-dimethoxy-2,2′-bipyridine)2(poly(vinylimidazole))10Cl]+ or [Os(4,4′-dimethyl-2,2′-bipyridine)2(poly(vinylimidazole))10Cl]+ as mediators, and carbon nanotube conductive scaffolds in films on graphite electrodes provides enzyme electrodes for glucose oxidation. The recombinant enzyme and a deglycosylated form, both expressed in Pichia pastoris, are investigated and compared as biocatalysts for glucose oxidation using flow injection amperometry and voltammetry. In the presence of 5 mM glucose in phosphate-buffered saline (PBS) (50 mM phosphate buffer solution, pH 7.4, with 150 mM NaCl), higher glucose oxidation current densities, 0.41 mA cm–2, are obtained from enzyme electrodes containing the deglycosylated form of the enzyme. The optimized glucose-oxidizing anode, prepared using deglycosylated enzyme coimmobilized with [Os(4,4′-dimethyl-2,2′-bipyridine)2(poly(vinylimidazole))10Cl]+ and carbon nanotubes, was coupled with an oxygen-reducing bilirubin oxidase on gold nanoparticle dispersed on gold electrode as a biocathode to provide a membraneless fully enzymatic fuel cell. A maximum power density of 275 μW cm–2 is obtained in 5 mM glucose in PBS, the highest to date under these conditions, providing sufficient power to enable wireless transmission of a signal to a data logger. When tested in whole human blood and unstimulated human saliva maximum power densities of 73 and 6 μW cm–2 are obtained for the same fuel cell configuration, respectively.
Co-reporter:Partha Sarathi Jana, Krishna Katuri, Paul Kavanagh, Amit Kumar and Dónal Leech
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 19) pp:9039-9046
Publication Date(Web):26 Mar 2014
DOI:10.1039/C4CP01023J
Harnessing, and understanding the mechanisms of growth and activity of, biofilms of electroactive bacteria (EAB) on solid electrodes is of increasing interest, for application to microbial fuel and electrolysis cells. Microbial electrochemical cell technology can be used to generate electricity, or higher value chemicals, from organic waste. The capability of biofilms of electroactive bacteria to transfer electrons to solid anodes is a key feature of this emerging technology, yet the electron transfer mechanism is not fully characterized as yet. Acetate oxidation current generated from biofilms of an EAB, Geobacter sulfurreducens, on graphite electrodes as a function of time does not correlate with film thickness. Values of film thickness, and the number and local concentration of electrically connected redox sites within Geobacter sulfurreducens biofilms as well as a charge transport diffusion co-efficient for the biofilm can be estimated from non-turnover voltammetry. The thicker biofilms, of 50 ± 9 μm, display higher charge transport diffusion co-efficient than that in thinner films, as increased film porosity of these films improves ion transport, required to maintain electro-neutrality upon electrolysis.
Co-reporter:Isioma Osadebe ; Dónal Leech
ChemElectroChem 2014 Volume 1( Issue 11) pp:1988-1993
Publication Date(Web):
DOI:10.1002/celc.201402136
Abstract
The addition of multi-walled carbon nanotubes (MWCNTs) to enzymatic electrodes based on either glucose oxidase (GOx), or an oxygen-insensitive flavin adenine dinucleotide-dependent glucose dehydrogenase (FADGDH), increases the amount of {Os(4,4′-dimethyl-2,2′-bipyridine)2[poly(vinylimidazole)]10Cl}Cl redox polymer at the electrode surface, indicating that MWCNTs provide a surface for the immobilisation of film components. Glucose oxidation is highest for films with 68 % (w/w) MWCNTs, and a decrease is observed with larger amounts; this decrease is related to a decrease in retained enzyme activity. Enzymatic electrodes provide 4.2 mA cm−2 current density at 0.12 V versus Ag/AgCl, for GOx-based electrodes, compared to 2.7 mA cm−2 for FADGDH-based electrodes in 50 mM phosphate-buffered saline containing 150 mM NaCl at 37 °C. Current densities of 0.52 and 1.1 mA cm−2 are obtained for FADGDH and GOx-based electrodes, respectively, operating at physiologically relevant 5 mM glucose concentrations. These enzymatic electrodes, thus, show promise for application as anodes in enzymatic fuel cells for in vivo or ex vivo power generation.
Co-reporter:Amit Kumar, Peter Ó Conghaile, Krishna Katuri, Piet Lens and Dónal Leech
RSC Advances 2013 vol. 3(Issue 41) pp:18759-18761
Publication Date(Web):08 Aug 2013
DOI:10.1039/C3RA42953A
Introduction of arylamine functional groups to graphite electrodes results in improved initial catalysis for acetate oxidation by microbial biofilms over that observed on unmodified anodes. Arylamine modified anodes achieve a current density of 3.4 A m−2 whilst unmodified anodes achieve only 1.3 A m−2 during the first batch feed cycle. The surface functionalization strategy provides a route to enhancing microbial bioelectrochemical systems process performance and for studying the complex mechanisms involved in such systems.
Co-reporter:Peter Ó Conghaile, Sascha Pöller, Domhnall MacAodha, Wolfgang Schuhmann, Dónal Leech
Biosensors and Bioelectronics 2013 Volume 43() pp:30-37
Publication Date(Web):15 May 2013
DOI:10.1016/j.bios.2012.11.036
Newly synthesised osmium complex-modified redox polymers were tested for potential application as mediators in glucose oxidising enzyme electrodes for application to biosensors or biofuel cells. Coupling of osmium complexes containing amine functional groups to epoxy-functionalised polymers of variable composition provides a range of redox polymers with variation possible in redox potential and physicochemical properties. Properties of the redox polymers as mediators for glucose oxidation were investigated by co-immobilisation onto graphite with glucose oxidase or FAD-dependent glucose dehydrogenase using a range of crosslinkers and in the presence and absence of multiwalled carbon nanotubes. Electrodes prepared by immobilising [P20-Os(2,2′-bipyridine)2(4-aminomethylpyridine)Cl].PF6, carbon nanotubes and glucose oxidase exhibit glucose oxidation current densities as high as 560 μA cm−2 for PBS containing 100 mM glucose at 0.45 V vs. Ag/AgCl. Films prepared by crosslinking [P20-Os(4,4′-dimethoxy-2,2′-bipyridine)2(4-aminomethylpyridine)Cl].PF6, an FAD-dependent glucose dehydrogenase, and carbon nanotubes achieve current densities of 215 μA cm−2 in 5 mM glucose at 0.2 V vs. Ag/AgCl, showing some promise for application to glucose oxidising biosensors or biofuel cells.Graphical abstractHighlights► Novel osmium redox polymers prepared using covalent binding approach. ► Enzyme electrodes using redox polymers, enzymes and multiwalled carbon nanotubes provide high current density for glucose oxidation. ► J of 215 μA cm−2 for 5 mM glucose PBS solutions at 0.2 V vs. Ag/AgCl.
Co-reporter:Domhnall MacAodha;Peter Ó Conghaile;Brenda Egan;Dr. Paul Kavanagh ; Dónal Leech
ChemPhysChem 2013 Volume 14( Issue 10) pp:2302-2307
Publication Date(Web):
DOI:10.1002/cphc.201300239
Abstract
Co-immobilisation of three separate multiple blue copper oxygenases, a Myceliophthora thermophila laccase, a Streptomyces coelicolor laccase and a Myrothecium verrucaria bilirubin oxidase, with an [Os(2,2′-bipyridine)2(polyvinylimidazole)10Cl]+/2+ redox polymer in the presence of multi-walled carbon nanotubes (MWCNTs) on graphite electrodes results in enzyme electrodes that produce current densities above 0.5 mA cm−2 for oxygen reduction at an applied potential of 0 V versus Ag/AgCl. Fully enzymatic membraneless fuel cells are assembled with the oxygen-reducing enzyme electrodes connected to glucose-oxidising anodes based on co-immobilisation of glucose oxidase or a flavin adenine dinucleotide-dependent glucose dehydrogenase with an [Os(4,4′-dimethyl-2,2′-bipyridine)2(polyvinylimidazole)10Cl]+/2+ redox polymer in the presence of MWCNTs on graphite electrodes. These fuel cells can produce power densities of up to 145 μW cm−2 on operation in pH 7.4 phosphate buffer solution at 37 °C containing 150 mM NaCl, 5 mM glucose and 0.12 mM O2. The fuel cells based on Myceliophthora thermophila laccase enzyme electrodes produce the highest power density if combined with glucose oxidase-based anodes. Although the maximum power density of a fuel cell of glucose dehydrogenase and Myceliophthora thermophila laccase enzyme electrodes decreases from 110 μW cm−2 in buffer to 60 μW cm−2 on testing in artificial plasma, it provides the highest power output reported to date for a fully enzymatic glucose-oxidising, oxygen-reducing fuel cell in artificial plasma.
Co-reporter:Dónal Leech, Paul Kavanagh, Wolfgang Schuhmann
Electrochimica Acta 2012 Volume 84() pp:223-234
Publication Date(Web):1 December 2012
DOI:10.1016/j.electacta.2012.02.087
There is an increasing interest in replacing non-selective metal catalysts, currently used in low temperature fuel cells, with enzymes as catalysts. Specific oxidation of fuel and oxidant by enzymes as catalysts yields enzymatic fuel cells. If the catalysts can be immobilised at otherwise inert anode and cathode materials, this specificity of catalysis obviates the requirement for fuel cell casings and membranes permitting fuel cell configurations amenable to miniaturisation to be adopted. Such configurations have been proposed for application to niche areas of power generation: powering remotely located portable electronic devices, or implanted biomedical devices, for example. We focus in this review on recent efforts to improve electron transfer between the enzymes and electrodes, in the presence or absence of mediators, with most attention on research aimed at implantable or semi-implantable enzymatic fuel cells that harvest the body's own fuel, glucose, coupled to oxygen reduction, to provide power to biomedical devices. This ambitious goal is still at an early stage, with device power output and stability representing major challenges. A comparison of performance of enzymatic fuel cell electrodes and assembled fuel cells is attempted in this review, but is hampered in general by lack of availability of, and conformity to, standardised testing and reporting protocols for electrodes and cells. We therefore highlight reports that focus on this requirement. Ultimately, insight gained from enzymatic fuel cell research will lead to improved biomimetics of enzyme catalysts for fuel cell electrodes. These biomimetics will mimic enzyme catalytic sites and the structural flexibility of the protein assembly surrounding the catalytic site.
Co-reporter:Domhnall MacAodha, Maria Luisa Ferrer, Peter Ó Conghaile, Paul Kavanagh and Dónal Leech
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 42) pp:14667-14672
Publication Date(Web):24 Aug 2012
DOI:10.1039/C2CP42089A
Co-immobilisation approaches for preparation of glucose-oxidising films of [Os(2,2′-bipyridine)2(poly-vinylimidazole)10Cl] and glucose oxidase on glassy carbon electrodes are compared. Electrodes prepared by crosslinking using glutaraldehyde vapour, without and with a NaBH4 reduction, provide higher glucose oxidation current than those prepared using a well-established diepoxide method. Addition of multi walled carbon nanotubes to the film deposition solutions produces an enhanced glucose oxidation current density of 5 mA cm−2 at 0.35 V vs. Ag/AgCl, whilst improving the operational stability of the current signal. Carbon nanotube, glutaraldehyde vapour crosslinked, films on electrodes, reduced by NaBH4, retain 77% of initial catalytic current over 24 hours of continuous amperometric testing in a 37 °C, 50 mM phosphate buffer solution containing 150 mM NaCl and 100 mM glucose. Potential application of this approach to implantable enzymatic biofuel cells is demonstrated by production of glucose oxidation currents, under pseudo-physiological conditions, using mediating films with lower redox potentials.
Co-reporter:Susan Boland and Dónal Leech
Analyst 2012 vol. 137(Issue 1) pp:113-117
Publication Date(Web):21 Oct 2011
DOI:10.1039/C1AN15537G
Highly ordered macroporous electrodes are prepared by electro-deposition of gold through a polystyrene sphere template. Drop-coating redox polymer and either glucose oxidase, for the anode, or Melanocarpus albomyceslaccase, for the cathode on the macroporous gold provides film-coated electrodes for assembly of membrane-less glucose/oxygen enzymatic fuel cells (EFC) in pH 7.4 buffer containing 10 mM glucose and 0.15 M NaCl. Under these conditions the maximum power density of 17 μWcm−2 for EFCs using films adsorbed to planar gold electrodes increased to 38 μWcm−2 for films adsorbed to 2½ sphere gold macroporous electrodes.
Co-reporter:Krishna P. Katuri, Ann-Marie Enright, Vincent O'Flaherty, Dónal Leech
Bioelectrochemistry 2012 Volume 87() pp:164-171
Publication Date(Web):October 2012
DOI:10.1016/j.bioelechem.2011.12.002
The ability of dual-chambered microbial fuel cell, fed with slaughterhouse wastewater with an anaerobic mixed-sludge as initial source of bacteria, to generate power is investigated. MFC voltage generation across a fixed 100 Ω load indicates power generation capability, with power production correlated to changes in anolyte VFA content. A maximum MFC power density of 578 mW/m2 is obtained for an MFC developed under 100 Ω load, compared to a maximum power density of 277 mW/m2 for an MFC developed under higher resistance (1 MΩ) control conditions. Voltammetry of the biofilm developed under 100 Ω load displays a current–voltage signal indicative of bioelectrocatalytic oxidation of feed at a potential of − 0.35 V vs. Ag/AgCl, compared to negligible signals for biofilms developed under control conditions. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA gene fragments reveals that the anodic bacterial communities in reactors operated under 100 Ω load result in communities of lower diversity than for the control condition, with Geovibrio ferrireducens dominant in the anodic biofilm community. These results indicate that in MFC reactors, functionally stable electroactive bacteria are enriched under 100 Ω load compared to high resistance control conditions, and were able to sustain higher power in MFCs.Highlights► A two-chambered microbial fuel cell generates electricity from slaughterhouse wastewater. ► Fuel cell voltage-time profile correlates with production of anolyte VFA content. ► Biofilm developed under 100 Ω load yields increased power compared to that developed under 1 MΩ. ► Bacterial community analysis indicates external load induces bacterial diversity.
Co-reporter:Peter Jenkins, Saara Tuurala, Anu Vaari, Matti Valkiainen, Maria Smolander, Dónal Leech
Bioelectrochemistry 2012 Volume 87() pp:172-177
Publication Date(Web):October 2012
DOI:10.1016/j.bioelechem.2011.11.011
Current generation by mediated enzyme electron transfer at electrode surfaces can be harnessed to provide biosensors and redox reactions in enzymatic fuel cells. A glucose/oxygen enzymatic fuel cell can provide power for portable and implantable electronic devices. High volume production of enzymatic fuel cell prototypes will likely require printing of electrode and catalytic materials. Here we report on preparation and performance of, completely enzymatic, printed glucose/oxygen biofuel cells. The cells are based on filter paper coated with conducting carbon inks, enzyme and mediator. A comparison of cell performance using a range of mediators for either glucose oxidase (GOx) or aldose dehydrogenase (ALDH) oxidation of glucose at the anode and ABTS and a fungal laccase, for reduction of oxygen at the cathode, is reported. Highest power output, although of limited stability, is observed for ALDH anodes mediated by an osmium complex, providing a maximum power density of 3.5 μW cm− 2 at 0.34 V, when coupled to a laccase/ABTS cathode. The stability of cell voltage in a biobattery format, above a threshold of 200 mV under a moderate 75 kΩ load, is used to benchmark printed fuel cell performance. Highest stability is obtained for printed fuel cells using ALDH, providing cell voltages over the threshold for up to 74 h, compared to only 2 h for cells with anodes using GOx. These results provide promising directions for further development of mass-producible, completely enzymatic, printed biofuel cells.Highlights► Enzymatic fuel cells prepared by printing enzyme, mediator and carbon onto filter paper. ► Mediated glucose oxidase or aldose dehydrogenase anodes are coupled to a laccase/ABTS cathode. ► Highest power from cells based on aldose dehydrogenase using osmium complex as mediator. ► Best cell voltage stability using aldose dehyrogenase anodes with a TMPD mediator.
Co-reporter:Krishna P. Katuri, Saravanan Rengaraj, Paul Kavanagh, Vincent O’Flaherty, and Dónal Leech
Langmuir 2012 Volume 28(Issue 20) pp:7904-7913
Publication Date(Web):April 23, 2012
DOI:10.1021/la2047036
Biofilms of the electroactive bacterium Geobacter sulfurreducens were induced to grow on graphite-rod electrodes under a potential of 0 V (vs Ag/AgCl) in the presence of acetate as an electron donor. Increased anodic currents for bioelectrocatalytic oxidation of acetate were obtained when the electrodes were incubated for longer periods with periodic electron-donor feeding. The maximum current density for acetate oxidation increased 2.8-fold, and the biofilm thickness increased by 4.25-fold, over a time period of 83–147 h. Cyclic voltammetry in the presence of acetate supports a model of heterogeneous electron transfer, one electron at time, from biofilm to electrode through a dominant redox species centered at −0.41 V vs Ag/AgCl. Voltammetry performed under nonturnover conditions provided an estimate of the surface coverage of the redox species of 25 nmol/cm2. This value was used to estimate a redox species concentration of 7.3 mM within the 34-μm-thick biofilm and a charge-transport diffusion coefficient of 3.6 × 10–7 cm2/s. This value of diffusion coefficient is greater than that observed in traditional thin-film voltammetric studies with redox polymer films containing much higher surface concentrations of redox species and might be associated with proton transport to ensure electroneutrality within the biofilm upon electrolysis.
Co-reporter:Krishna Katuri, M. Luisa Ferrer, María C. Gutiérrez, Ricardo Jiménez, Francisco del Monte and Dónal Leech
Energy & Environmental Science 2011 vol. 4(Issue 10) pp:4201-4210
Publication Date(Web):06 Sep 2011
DOI:10.1039/C1EE01477C
Three-dimensional microchannelled nanocomposite electrodes fabricated by ice-segregation induced self-assembly of chitosan-dispersed multiwall carbon nanotubes are shown to provide a scaffold for growth of electroactive bacteria for use as acetate-oxidizing bioanodes in bioelectrochemical systems. The hierarchical structure provides a conductive surface area available for G. sulfurreducens colonization, with a flow through configuration along the electrode providing a substrate for bacterial colonization and bio-electrochemical processes. This configuration, whilst resulting in sub-monolayer biofilm coverage over the three-dimensional surface, is capable of providing acetate oxidation current densities of up to 24.5 A m−2, equating to a volumetric current density of 19 kA m−3, in the flow-through configuration. Such bioanodes, when operated in non-optimized flow-through microbial fuel cell configuration, provide a maximum power density of 2.87 W m−2, which is equivalent to 2.0 kW m−3 volumetric power density.
Co-reporter:Saravanan Rengaraj, Vigneshwaran Mani, Paul Kavanagh, James Rusling and Dónal Leech
Chemical Communications 2011 vol. 47(Issue 43) pp:11861-11863
Publication Date(Web):06 Oct 2011
DOI:10.1039/C1CC15002B
Layer-by-layer (LBL) assembly of alternate osmium redox polymers and glucose oxidase, at anode, and laccase, at cathode, using graphite electrodes form a membrane-less glucose/O2 enzymatic fuel cell providing a power density of 103 μW cm−2 at pH 5.5.
Co-reporter:Tunc Catal, Paul Kavanagh, Vincent O’Flaherty, Dónal Leech
Journal of Power Sources 2011 Volume 196(Issue 5) pp:2676-2681
Publication Date(Web):1 March 2011
DOI:10.1016/j.jpowsour.2010.11.031
Direct generation of electricity from a mixture of carbon sources was examined using single chamber mediator-less air cathode microbial fuel cells (MFCs) at sub-ambient temperatures. Electricity was directly generated from a carbon source mixture of d-glucose, d-galactose, d-xylose, d-glucuronic acid and sodium acetate at 30 °C and <20 °C (down to 4 °C). Anodic biofilms enriched at different temperatures using carbon source mixtures were examined using epi-fluorescent, scanning electron microscopy, and cyclic voltammetry for electrochemical evaluation. The maximum power density obtained at different temperatures ranged from 486 ± 68 mW m−2 to 602 ± 38 mW m−2 at current density range of 0.31 mA cm−2 to 0.41 mA cm−2 (14 °C and 30 °C, respectively). Coulombic efficiency increased with decreasing temperature, and ranged from 24 ± 3 to 38 ± 1% (20 °C and 4 °C, respectively). Chemical oxygen demand (COD) removal was over 68% for all carbon sources tested. Our results demonstrate adaptation, by gradual increase of cold-stress, to electricity production in MFCs at sub-ambient temperatures.
Co-reporter:Saravanan Rengaraj, Paul Kavanagh, Dónal Leech
Biosensors and Bioelectronics 2011 30(1) pp: 294-299
Publication Date(Web):
DOI:10.1016/j.bios.2011.09.032
Co-reporter:Krishna P. Katuri, Paul Kavanagh, Saravanan Rengaraj and Dónal Leech
Chemical Communications 2010 vol. 46(Issue 26) pp:4758-4760
Publication Date(Web):20 May 2010
DOI:10.1039/C003342A
Growth of biofilms of G. sulfurreducens on glassy carbon that yield a bioelectrocatalytic response to acetate oxidation is achieved using a fixed applied potential, with current density for acetate oxidation scaling with applied potential. In contrast biofilms grown under electron acceptor-limiting conditions display redox signals shifted to lower potentials and do not oxidise acetate.
Co-reporter:Joanna Hajdukiewicz, Susan Boland, Paul Kavanagh, Dónal Leech
Biosensors and Bioelectronics 2010 Volume 25(Issue 5) pp:1037-1042
Publication Date(Web):15 January 2010
DOI:10.1016/j.bios.2009.09.020
This report describes a simple methodology for preparation of an enzyme-amplified amperometric DNA hybridisation assay using solution-phase ferrocenemethanol mediation of glucose oxidase oxidation of glucose. The recognition layer consists of amine-terminated ssDNA (designed for binding of the sequence ssrA gene of Listeria monocytogenes) bound within a carboxymethylated dextran film that is anchored to a graphite electrode. Anchoring sites are provided by electrochemical grafting of an arylamine to the carbon surface following in situ diazotisation of p-phenylenediamine. Hybridisation between the immobilised probe ssDNA and a biotin-labelled target ssDNA sequence is detected by following the oxidation of glucose upon addition of a glucose oxidase–avidinD conjugate and ferrocenemethanol. The stability of the anchored film permits washing and blocking steps to discriminate between hybridisation and non-specific binding. The signal current, measured by cyclic voltammetry and constant potential amperometry, scales with biotin-complementary DNA concentration, from 2.5 × 10−6 M to 3 × 10−7 M and a detection limit of 0.2 nmol in the 500 μL sample at the 3-mm diameter graphite electrode is estimated. Approaches to improve upon the analytical performance of this simple assay are highlighted.
Co-reporter:Susan Boland, Kevin Foster, Dónal Leech
Electrochimica Acta 2009 Volume 54(Issue 7) pp:1986-1991
Publication Date(Web):28 February 2009
DOI:10.1016/j.electacta.2008.09.066
The production of stable redox active layers on electrode surfaces is a key factor for the development of practical electronic and electrochemical devices. Here, we report on a comparison of the stability of redox layers formed by covalently coupling an osmium redox complex to pre-functionalized gold and graphite electrode surfaces. Pre-treatment of gold and graphite electrodes to provide surface carboxylic acid groups is achieved via classical thiolate self-assembled monolayer formation on gold surfaces and the electro-reduction of an in situ generated aryldiazonium salt from 4-aminobenzoic acid on gold, glassy carbon and graphite surfaces. These surfaces have been characterized by AFM and electrochemical blocking studies. The surface carboxylate is then used to tether an osmium complex, [Os(2,2′-bipyridyl)2(4-aminomethylpyridine)Cl]PF6, to provide a covalently bound redox active layer, E0′E0′ of 0.29 V (vs. Ag/AgCl in phosphate buffer, pH 7.4), on the pre-treated electrodes. The aryldiazonium salt-treated carbon-based surfaces showed the greatest stability, represented by a decrease of <5% in the peak current for the Os(II/III) redox transition of the immobilized complex over a 3-day period, compared to a decrease of 19% and 14% for the aryldiazonium salt treated and thiolate treated gold surfaces, respectively, over the same period.
Co-reporter:Susan Boland, Peter Jenkins, Paul Kavanagh, Dónal Leech
Journal of Electroanalytical Chemistry 2009 Volume 626(1–2) pp:111-115
Publication Date(Web):15 February 2009
DOI:10.1016/j.jelechem.2008.11.010
Films of redox hydrogels containing co-immobilized biocatalysts on electrodes show promise as biosensors and in biocatalytic fuel cells, provided issues of film stability can be addressed. Here we evaluate the stability of these systems chemically tethered, using a diepoxide crosslinker, to electrodes previously pre-treated to introduce surface amine groups. An osmium-based redox polymer, alone or combined with glucose oxidase or bilirubin oxidase, is tethered to gold substrates pre-treated with cysteamine or to graphite surfaces pre-treated by in situ generation and reduction of the diazonium salt from 1,4-phenylenediamine. After 48 h, graphite electrodes pre-treated to introduce the anchoring amine group retained up to 90 ± 3% of the original redox signal, whereas cysteamine pre-treated redox polymer modified electrodes retained only 31 ± 5% redox signal. Incorporation of biocatalysts into the redox active hydrogels gives rise to similar trends, as hydrogels containing glucose oxidase on pre-treated graphite retain 54 ± 6% of catalytic response after 48 h compared to only 23 ± 5% for gold electrodes pre-treated with cysteamine, a trend also reflected when the oxygen reducing bilirubin oxidase enzyme is employed. The chemical tethering to graphite pre-treated using diazonium salt chemistry provides a promising approach for stabilization of biosensor and biocatalytic fuel cells systems.
Co-reporter:Frédéric Barrière, Paul Kavanagh, Dónal Leech
Electrochimica Acta 2006 Volume 51(Issue 24) pp:5187-5192
Publication Date(Web):15 July 2006
DOI:10.1016/j.electacta.2006.03.050
Here we report on the design and study of a biofuel cell consisting of a glucose oxidase-based anode (Aspergillus niger) and a laccase-based cathode (Trametes versicolor) using osmium-based redox polymers as mediators of the biocatalysts’ electron transfer at graphite electrode surfaces. The graphite electrodes of the device are modified with the deposition and immobilization of the appropriate enzyme and the osmium redox polymer mediator. A redox polymer [Os(4,4′-diamino-2,2′bipyridine)2(poly{N-vinylimidazole})-(poly{N-vinylimidazole})9Cl]Cl (E0′ = −0.110 V versus Ag/AgCl) of moderately low redox potential is used for the glucose oxidizing anode and a redox polymer [Os(phenanthroline)2(poly{N-vinylimidazole})2-(poly{N-vinylimidazole})8]Cl2 (E0′ = 0.49 V versus Ag/AgCl) of moderately high redox potential is used at the dioxygen reducing cathode. The enzyme and redox polymer are cross-linked with polyoxyethylene bis(glycidyl ether). The working biofuel cell was studied under air at 37 °C in a 0.1 M phosphate buffer solution of pH range 4.4–7.4, containing 0.1 M sodium chloride and 10 mM glucose. Under physiological conditions (pH 7.4) maximum power density, evaluated from the geometric area of the electrode, reached 16 μW/cm2 at a cell voltage of 0.25 V. At lower pH values maximum power density was 40 μW/cm2 at 0.4 V (pH 5.5) and 10 μW/cm2 at 0.3 V (pH 4.4).
Co-reporter:D. Rochefort, D. Leech and R. Bourbonnais
Green Chemistry 2004 vol. 6(Issue 1) pp:14-24
Publication Date(Web):12 Dec 2003
DOI:10.1039/B311898N
The participation of biological agents in pulp bleaching systems has received a lot of attention from research teams around the world, driven by the environmental benefits that biobleaching could bring. Nature showed us the ability of some of its agents, such as wood-decaying fungi, to delignify and bleach wood and wood pulp. What we need to do is to enhance the efficiency of such agents to make them cope with the fast pace of our modern pulp mills. To do so, a profound understanding of the biobleaching system is required. Our efforts to discover new efficient mediators for the laccase-mediator system (LMS) brought us to use several techniques to analyse the reactions involved in mediated enzymatic delignification. Mostly based on electrochemistry, these techniques are reviewed in this paper, along with key results. Cyclic voltammetry was used to characterize electron transfer rates between each element of the LMS. We found, along with other authors, that the mediator redox potential has a great influence on its efficiency. We used bulk electrolysis to simulate the oxidative action of laccase on mediators and model compounds of lignin. Such electrolysis techniques allowed us to study mediated lignin oxidation outside of normal laccase working conditions. Finally, an electrolysis-based method for mediated pulp delignification that we developed, based upon our research on biobleaching, is presented.
Co-reporter:Frédéric Barrière, Yvonne Ferry, Dominic Rochefort, Dónal Leech
Electrochemistry Communications 2004 Volume 6(Issue 3) pp:237-241
Publication Date(Web):March 2004
DOI:10.1016/j.elecom.2003.12.006
Electrodes modified with co-immobilized redox enzymes and redox polymers can be used to form membrane-less biofuel cells. In this communication, we report on our initial studies of a membrane-less biofuel cell concept using an osmium-based redox polymer for laccase-mediated reduction of oxygen coupled to glucose oxidase-mediated oxidation of glucose. We then present a thermodynamic examination of mediators of laccase oxygen reduction, and stemming from this, target two redox polymers of potential use, an osmium-based redox polymer (E0′+0.40 V vs. Ag/AgCl) and a ruthenium-based redox polymer (E0′+0.63 V vs. Ag/AgCl). The former shows promise for use in membrane-less biofuel cell cathodes, whilst the latter’s redox potential is too high to be an effective mediator of oxygen reduction by the Trametes versicolor laccase used in this study.
Co-reporter:Dominic Rochefort, Robert Bourbonnais, Dónal Leech and Michael G. Paice
Chemical Communications 2002 (Issue 11) pp:1182-1183
Publication Date(Web):26 Apr 2002
DOI:10.1039/B202621J
We have studied the oxidation of lignin model compounds by organic and transition metal-based mediators using either an enzyme or an electrolysis cell as the mediator oxidizing agent. Electrolysis of inorganic mediator seems a promising technology for pulp delignification.
Co-reporter:Huangxian Ju, Dónal Leech
Journal of Electroanalytical Chemistry 2000 Volume 484(Issue 2) pp:150-156
Publication Date(Web):17 April 2000
DOI:10.1016/S0022-0728(00)00071-1
A novel protein monolayer modified electrode has been prepared by the self-assembly of metallothionein (MT) at a gold disk electrode. The properties of MT in Tris–HCl buffer and in the monolayer are studied by using cyclic voltammetry and differential pulse voltammetry with a gold disk electrode. In the negative sweep, the voltammogram of MT in buffer shows two small peaks and different electrochemical behaviour from that at a mercury electrode. Cd2+ complexed to the thionein can easily be replaced by Hg2+ ions, and Hg2+ ions can firmly adsorb in the MT monolayer with a saturation coverage of (2.78±0.29)×10−10 mol cm−2. This behaviour has been used to preconcentrate trace Hg2+ for its determination by cathodic stripping differential pulse voltammetry. The cathodic stripping peak current is proportional to Hg2+ concentration in the range of 0.15–3 μM and the detection limit is ca. 0.08 μM (16 ppb) with a 2 min open circuit accumulation step. The relative standard deviation is 7.2% at 0.4 μM Hg2+ concentration (n=4). At higher concentration the adsorption of Hg2+exhibits a response similar to that expected for a Langmuir adsorption isotherm with the stability constant of (4.0±0.2)×105 M−1.
Co-reporter:Peter Jenkins, Saara Tuurala, Anu Vaari, Matti Valkiainen, Maria Smolander, Dónal Leech
Enzyme and Microbial Technology (10 March 2012) Volume 50(Issue 3) pp:181-187
Publication Date(Web):10 March 2012
DOI:10.1016/j.enzmictec.2011.12.002
Enzyme electrodes show great potential for many applications, as biosensors and more recently as anodes and cathodes in biocatalytic fuel cells for power generation. Enzymes have advantages over metal catalysts, as they provide high specificity and reaction rates, while operating under mild conditions. Here we report on studies related to development of mass-producible, completely enzymatic printed glucose/oxygen biofuel cells. The cells are based on filter paper coated with conducting carbon inks containing mediators and laccase, for reduction of oxygen, or aldose dehydrogenase, for oxidation of glucose. Mediator performance in these printed formats is compared to relative rate constants for the enzyme–mediator reaction in solution, for a range of anode and cathode mediators. The power output and stability of fuels cells using an acidophilic laccase isolated from Trametes hirsuta is greater, at pH 5, than that for cells based on Melanocarpus albomyces laccase, that shows optimal activity closer to neutral pH, at pH 6. Highest power output, although of limited stability, was observed for ThL/ABTS cathodes, providing a maximum power density of 3.5 μW cm−2 at 0.34 V, when coupled to an ALDH glucose anode mediated by an osmium complex. The stability of cell voltage above a threshold of 200 mV under a moderate 75 kΩ load is used to benchmark printed fuel cell performance. Highest stability was obtained for a printed fuel cell using osmium complexes as mediators of glucose oxidation by aldose dehydrogenase, and oxygen reduction by T. hirsuta laccase, maintaining cell voltage above 200 mV for 137 h at pH 5. These results provide promising directions for further development of mass-producible, completely enzymatic, printed biofuel cells.Download full-size image
Co-reporter:Saravanan Rengaraj, Vigneshwaran Mani, Paul Kavanagh, James Rusling and Dónal Leech
Chemical Communications 2011 - vol. 47(Issue 43) pp:NaN11863-11863
Publication Date(Web):2011/10/06
DOI:10.1039/C1CC15002B
Layer-by-layer (LBL) assembly of alternate osmium redox polymers and glucose oxidase, at anode, and laccase, at cathode, using graphite electrodes form a membrane-less glucose/O2 enzymatic fuel cell providing a power density of 103 μW cm−2 at pH 5.5.
Co-reporter:Partha Sarathi Jana, Krishna Katuri, Paul Kavanagh, Amit Kumar and Dónal Leech
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 19) pp:NaN9046-9046
Publication Date(Web):2014/03/26
DOI:10.1039/C4CP01023J
Harnessing, and understanding the mechanisms of growth and activity of, biofilms of electroactive bacteria (EAB) on solid electrodes is of increasing interest, for application to microbial fuel and electrolysis cells. Microbial electrochemical cell technology can be used to generate electricity, or higher value chemicals, from organic waste. The capability of biofilms of electroactive bacteria to transfer electrons to solid anodes is a key feature of this emerging technology, yet the electron transfer mechanism is not fully characterized as yet. Acetate oxidation current generated from biofilms of an EAB, Geobacter sulfurreducens, on graphite electrodes as a function of time does not correlate with film thickness. Values of film thickness, and the number and local concentration of electrically connected redox sites within Geobacter sulfurreducens biofilms as well as a charge transport diffusion co-efficient for the biofilm can be estimated from non-turnover voltammetry. The thicker biofilms, of 50 ± 9 μm, display higher charge transport diffusion co-efficient than that in thinner films, as increased film porosity of these films improves ion transport, required to maintain electro-neutrality upon electrolysis.
Co-reporter:Domhnall MacAodha, Maria Luisa Ferrer, Peter Ó Conghaile, Paul Kavanagh and Dónal Leech
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 42) pp:NaN14672-14672
Publication Date(Web):2012/08/24
DOI:10.1039/C2CP42089A
Co-immobilisation approaches for preparation of glucose-oxidising films of [Os(2,2′-bipyridine)2(poly-vinylimidazole)10Cl] and glucose oxidase on glassy carbon electrodes are compared. Electrodes prepared by crosslinking using glutaraldehyde vapour, without and with a NaBH4 reduction, provide higher glucose oxidation current than those prepared using a well-established diepoxide method. Addition of multi walled carbon nanotubes to the film deposition solutions produces an enhanced glucose oxidation current density of 5 mA cm−2 at 0.35 V vs. Ag/AgCl, whilst improving the operational stability of the current signal. Carbon nanotube, glutaraldehyde vapour crosslinked, films on electrodes, reduced by NaBH4, retain 77% of initial catalytic current over 24 hours of continuous amperometric testing in a 37 °C, 50 mM phosphate buffer solution containing 150 mM NaCl and 100 mM glucose. Potential application of this approach to implantable enzymatic biofuel cells is demonstrated by production of glucose oxidation currents, under pseudo-physiological conditions, using mediating films with lower redox potentials.
Co-reporter:Krishna P. Katuri, Paul Kavanagh, Saravanan Rengaraj and Dónal Leech
Chemical Communications 2010 - vol. 46(Issue 26) pp:NaN4760-4760
Publication Date(Web):2010/05/20
DOI:10.1039/C003342A
Growth of biofilms of G. sulfurreducens on glassy carbon that yield a bioelectrocatalytic response to acetate oxidation is achieved using a fixed applied potential, with current density for acetate oxidation scaling with applied potential. In contrast biofilms grown under electron acceptor-limiting conditions display redox signals shifted to lower potentials and do not oxidise acetate.
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