Publications (9)28.52 Total impact
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Article: Optimization of a Membraneless Glucose/Oxygen Enzymatic Fuel Cell Based on a Bioanode with High Coulombic Efficiency and Current Density.
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ABSTRACT: After initial testing and optimization of anode biocatalysts, a membraneless glucose/oxygen enzymatic biofuel cell possessing high coulombic efficiency and power output was fabricated and characterized. Two sugar oxidizing enzymes, namely, pyranose dehydrogenase from Agaricus meleagris (AmPDH) and flavodehydrogenase domains of various cellobiose dehydrogenases (DHCDH ) were tested during the pre-screening. The enzymes were mixed, "wired" and entrapped in a low-potential Os-complex-modified redox-polymer hydrogel immobilized on graphite. This anode was used in combination with a cathode based on bilirubin oxidase from Myrothecium verrucaria adsorbed on graphite. Optimization showed that the current density for the mixed enzyme electrode could be further improved by using a genetically engineered variant of the non-glycosylated flavodehydrogenase domain of cellobiose dehydrogenase from Corynascus thermophilus expressed in E. coli (ngDHCtCDHC310Y ) with a high glucose-turnover rate in combination with an Os-complex-modified redox polymer with a high concentration of Os complexes as well as a low-density graphite electrode. The optimized biofuel cell with the AmPDH/ngDHCtCDHC310Y anode showed not only a similar maximum voltage as with the biofuel cell based only on the ngDHCtCDHC310Y anode (0.55 V) but also a substantially improved maximum power output (20 μW cm(-2) ) at 300 mV cell voltage in air-saturated physiological buffer. Most importantly, the estimated half-life of the mixed biofuel cell can reach up to 12 h, which is apparently longer than that of a biofuel cell in which the bioanode is based on only one single enzyme.ChemPhysChem 04/2013; · 3.41 Impact Factor -
Article: Mutual enhancement of the current density and the coulombic efficiency for a bioanode by entrapping bi-enzymes with Os-complex modified electrodeposition paints
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ABSTRACT: A bioanode with high current density and coulombic efficiency was developed by co-immobilization of pyranose dehydrogenase from Agaricus meleagris (AmPDH) with the dehydrogenase domain of cellobiose dehydrogenase from Corynascus thermophiles (recDHCtCDH) expressed recombinantly in Escherichia coli. The two enzymes were entrapped in Os-complex modified electrodeposition polymers (Os-EDPs) with specifically adapted redox potential by means of chemical co-deposition. AmPDH oxidizes glucose at both the C2 and C3 positions whereas recDHCtCDH oxidizes glucose only at the C1 position. Electrochemical measurements reveal that maximally 6 electrons can be harvested from one glucose molecule at the two-enzyme anode via a cascade reaction, as AmPDH oxidizes the products formed from of the recDHCtCDH catalyzed substrate oxidation and vice versa. Furthermore, a significant increase in current density can be obtained by combining AmPDH and recDHCtCDH in a single modified electrode. We propose the use of this bioanode in biofuel cells with increased current density and coulombic efficiency. Keywords Cellobiose dehydrogenase (CDH); Coulombic efficiency; Pyranose dehydrogenase (PDH); Os-complex modified polymer; Redox polymer; Electron transferBiosensors and Bioelectronics 02/2013; 40(1):308-314. · 5.60 Impact Factor -
Article: Carbon Cloth/Carbon Nanotube Electrodes for Biofuel Cells Development
Electroanalysis 10/2012; · 2.87 Impact Factor -
Article: A new synthesis route for Os-complex modified redox polymers for potential biofuel cell applications.
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ABSTRACT: A new synthesis route for Os-complex modified redox polymers was developed. Instead of ligand exchange reactions for coordinative binding of suitable precursor Os-complexes at the polymer, Os-complexes already exhibiting the final ligand shell containing a suitable functional group were bound to the polymer via an epoxide opening reaction. By separation of the polymer synthesis from the ligand exchange reaction at the Os-complex, the modification of the same polymer backbone with different Os-complexes or the binding of the same Os-complex to a number of different polymer backbones becomes feasible. In addition, the Os-complex can be purified and characterized prior to its binding to the polymer. In order to further understand and optimize suitable enzyme/redox polymer systems concerning their potential application in biosensors or biofuel cells, a series of redox polymers was synthesized and used as immobilization matrix for Trametes hirsuta laccase. The properties of the obtained biofuel cell cathodes were compared with similar biocatalytic interfaces derived from redox polymers obtained via ligand exchange reaction of the parent Os-complex with a ligand integrated into the polymer backbone during the polymer synthesis.Bioelectrochemistry (Amsterdam, Netherlands) 12/2011; 87:178-84. · 2.65 Impact Factor -
Article: Electron transfer between genetically modified Hansenula polymorpha yeast cells and electrode surfaces via Os-complex modified redox polymers.
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ABSTRACT: Graphite electrodes modified with redox-polymer-entrapped yeast cells were investigated with respect to possible electron-transfer pathways between cytosolic redox enzymes and the electrode surface. Either wild-type or genetically modified Hansenula polymorpha yeast cells over-expressing flavocytochrome b2 (FC b(2) ) were integrated into Os-complex modified electrodeposition polymers. Upon increasing the L-lactate concentration, an increase in the current was only detected in the case of the genetically modified cells. The overexpression of FC b(2) and the related amplification of the FC b(2) /L-lactate reaction cycle was found to be necessary to provide sufficient charge to the electron-exchange network in order to facilitate sufficient electrochemical coupling between the cells, via the redox polymer, to the electrode. The close contact of the Os-complex modified polymer to the cell wall appeared to be a prerequisite for electrically wiring the cytosolic FC b(2) /L-lactate redox activity and suggests the critical involvement of a plasma membrane redox system. Insights in the functioning of whole-cell-based bioelectrochemical systems have to be considered for the successful design of whole-cell biosensors or microbial biofuel cells.ChemPhysChem 02/2011; 12(4):806-13. · 3.41 Impact Factor -
Article: Redox electrodeposition polymers: adaptation of the redox potential of polymer-bound Os complexes for bioanalytical applications.
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ABSTRACT: The design of polymers carrying suitable ligands for coordinating Os complexes in ligand exchange reactions against labile chloro ligands is a strategy for the synthesis of redox polymers with bound Os centers which exhibit a wide variation in their redox potential. This strategy is applied to polymers with an additional variation of the properties of the polymer backbone with respect to pH-dependent solubility, monomer composition, hydrophilicity etc. A library of Os-complex-modified electrodeposition polymers was synthesized and initially tested with respect to their electron-transfer ability in combination with enzymes such as glucose oxidase, cellobiose dehydrogenase, and PQQ-dependent glucose dehydrogenase entrapped during the pH-induced deposition process. The different polymer-bound Os complexes in a library containing 50 different redox polymers allowed the statistical evaluation of the impact of an individual ligand to the overall redox potential of an Os complex. Using a simple linear regression algorithm prediction of the redox potential of Os complexes becomes feasible. Thus, a redox polymer can now be designed to optimally interact in electron-transfer reactions with a selected enzyme.Analytical and Bioanalytical Chemistry 10/2010; 398(4):1661-73. · 3.78 Impact Factor -
Article: Parallel synthesis of libraries of anodic and cathodic functionalized electrodeposition paints as immobilization matrix for amperometric biosensors.
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ABSTRACT: The integration of flexible anchoring groups bearing imidazolyl or pyridyl substituents into the structure of electrodeposition paints (EDP) is the basis for the parallel synthesis of a library containing 107 members of different cathodic and anodic EDPs with a high variation in polymer properties. The obtained EDPs were used as immobilization matrix for biosensor fabrication using glucose oxidase as a model enzyme. Amperometric glucose sensors based on the different EDPs showed a wide variation in their sensor characteristics with respect to the apparent Michaelis-Menten constant (KM(app)) representing the linear measuring range and the maximum current (Imax(app)). Based on these results first assumptions concerning the impact of different side chains in the EDP on the expected biosensor properties could be obtained allowing for an improved rational optimization of EDPs used as immobilization matrix in amperometric biosensors.Bioelectrochemistry 10/2007; 71(1):81-90. · 3.76 Impact Factor -
Article: Phenol biosensor based on electrochemically controlled integration of tyrosinase in a redox polymer
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ABSTRACT: An amperometric biosensor for the detection of phenolic compounds was developed based on the immobilization of tyrosinase within an Os-complex functionalized electrodeposition polymer. Integration of tyrosinase within the redox polymer assures efficient catechol recycling between the enzyme and the polymer bound redox sites. The non-manual immobilization procedure improves the reproducibility of fabrication process, greatly reduces the desorption of the enzyme from the immobilization layer, and, most importantly prevents fast inactivation of the enzyme by its substrate due to fast redox cycling. A two-layer sensor architecture was developed involving ascorbic acid oxidase entrapped within an electrodeposition polymer in a second layer on top of the redox polymer=tyrosinase layer. Using this sensor architecture it was possible to eliminate the current interference arising from direct ascorbate oxidation up to a concentration of 630 mM ascorbic acid. The effects of the polymer thickness, the enzyme= polymer ratio, and the applied potential were evaluated with respect to optimal sensor properties. The sensitivity of the optimized sensors for catechol was 6.1 nA mM-1 with a detection limit of 10 nM, and for phenol 0.15 nA mM-1 with a detection limit of 100 nM.Microchimica Acta 05/2007; 159:27-34. · 3.03 Impact Factor -
Article: Redox polymer-based reagentless horseradish peroxidase biosensors: Influence of the molecular structure of the polymer
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ABSTRACT: Reagentless amperometric biosensors were prepared using a variety of nitrogen donor groups containing co-polymers. The polymers were coordinated with Os-bis-N,N-(2,2′-bipyridil)-dichloride via a ligand exchange reaction thus assuring an efficient electron-transfer pathway between the polymer-entrapped horseradish peroxidase and the electrode surface by means of a sequence of electron-hopping steps. The impact of structural features of the polymer such as spacer length between the Os-complex and the polymer backbone or the ratio of 4-vinylpyridine and butylmethacrylate in a co-polymer on the activity of the horseradish peroxidase biosensors was investigated.Electrochimica Acta.
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Institutions
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2007–2011
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Ruhr-Universität Bochum
Bochum, North Rhine-Westphalia, Germany
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