@article{PinyouRuffPoelleretal.2016, author = {Pinyou, Piyanut and Ruff, Adrian and Poeller, Sascha and Alsaoub, Sabine and Leimk{\"u}hler, Silke and Wollenberger, Ursula and Schuhmann, Wolfgang}, title = {Wiring of the aldehyde oxidoreductase PaoABC to electrode surfaces via entrapment in low potential phenothiazine-modified redox polymers}, series = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society}, volume = {109}, journal = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society}, publisher = {Elsevier}, address = {Lausanne}, issn = {1567-5394}, doi = {10.1016/j.bioelechem.2015.12.005}, pages = {24 -- 30}, year = {2016}, abstract = {Phenothiazine-modified redox hydrogels were synthesized and used for the wiring of the aldehyde oxidoreductase PaoABC to electrode surfaces. The effects of the pH value and electrode surface modification on the biocatalytic activity of the layers were studied in the presence of vanillin as the substrate. The enzyme electrodes were successfully employed as bioanodes in vanillin/O-2 biofuel cells in combination with a high potential bilirubin oxidase biocathode. Open circuit voltages of around 700 mV could be obtained in a two compartment biofuel cell setup. Moreover, the use of a rather hydrophobic polymer with a high degree of crosslinking sites ensures the formation of stable polymer/enzyme films which were successfully used as bioanode in membrane-less biofuel cells. (C) 2015 Elsevier B.V. All rights reserved.}, language = {en} } @article{BierEhrentreichFoersterSchelleretal.1996, author = {Bier, Frank Fabian and Ehrentreich-F{\"o}rster, Eva and Scheller, Frieder W. and Makower, Alexander and Eremenko, A. V. and Wollenberger, Ursula and Bauer, Christian G. and Pfeiffer, Dorothea and Micheel, Burkhard}, title = {Ultrasensitive biosensors}, year = {1996}, language = {en} } @article{SzeponikMoellerPfeifferetal.1997, author = {Szeponik, Jan and M{\"o}ller, B. and Pfeiffer, Dorothea and Lisdat, Fred and Wollenberger, Ursula and Makower, Alexander and Scheller, Frieder W.}, title = {Ultrasensitive bienzyme sensor for adrenaline}, year = {1997}, language = {en} } @article{MakowerEremenkoStrefferetal.1996, author = {Makower, Alexander and Eremenko, A. V. and Streffer, Katrin and Wollenberger, Ursula and Scheller, Frieder W.}, title = {Tyrosinase-glucose dehydrogenase substrate-recycling biosensor : a highly sensitive measurement of phenolic compounds}, year = {1996}, language = {en} } @article{SchellerBistolasLiuetal.2005, author = {Scheller, Frieder W. and Bistolas, Nikitas and Liu, Songqin and J{\"a}nchen, Michael and Katterle, Martin and Wollenberger, Ursula}, title = {Thirty years of haemoglobin electrochemistry}, year = {2005}, abstract = {Electrochemical investigations of the blood oxygen carrier protein include both mediated and direct electron transfer. The reaction of haemoglobin (Hb) with typical mediators, e.g., ferricyanide, can be quantified by measuring the produced ferrocyanide which is equivalent to the Hb concentration. Immobilization of the mediator within the electrode body allows reagentless electrochemical measuring of Hb. On the other hand, entrapment of the protein within layers of polyclectrolytes, lipids, nanoparticles of clay or gold leads to a fast heterogeneous electron exchange of the partially denatured Hb. (c) 2005 Elsevier B.V. All rights reserved}, language = {en} } @article{YarmanSchulzSygmundetal.2014, author = {Yarman, Aysu and Schulz, Christopher and Sygmund, Cristoph and Ludwig, Roland and Gorton, Lo and Wollenberger, Ursula and Scheller, Frieder W.}, title = {Third generation ATP sensor with enzymatic analyte recycling}, series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, volume = {26}, journal = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, number = {9}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1040-0397}, doi = {10.1002/elan.201400231}, pages = {2043 -- 2048}, year = {2014}, abstract = {For the first time the direct electron transfer of an enzyme - cellobiose dehydrogenase, CDH - has been coupled with the hexokinase catalyzed competition for glucose in a sensor for ATP. To enhance the signal output for ATP, pyruvate kinase was coimmobilized to recycle ADP by the phosphoenolpyruvate driven reaction. The new sensor overcomes the limit of 1:1 stoichiometry of the sequential or competitive conversion of ATP by effective enzymatic recycling of the analyte. The anodic oxidation of the glucose converting CDH proceeds at electrode potentials below 0 mV vs. Ag vertical bar AgCl thus potentially interfering substances like ascorbic acid or catecholamines do not influence the measuring signal. The combination of direct electron transfer of CDH with the enzymatic recycling results in an interference-free and oxygen-independent measurement of ATP in the lower mu molar concentration range with a lower limit of detection of 63.3 nM (S/N=3).}, language = {en} } @article{SpricigoLeimkuehlerGortonetal.2015, author = {Spricigo, Roberto and Leimk{\"u}hler, Silke and Gorton, Lo and Scheller, Frieder W. and Wollenberger, Ursula}, title = {The Electrically Wired Molybdenum Domain of Human Sulfite Oxidase is Bioelectrocatalytically Active}, series = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, journal = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, number = {21}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1434-1948}, doi = {10.1002/ejic.201500034}, pages = {3526 -- 3531}, year = {2015}, abstract = {We report electron transfer between the catalytic molybdenum cofactor (Moco) domain of human sulfite oxidase (hSO) and electrodes through a poly(vinylpyridine)-bound [osmium(N,N'-methyl-2,2'-biimidazole)(3)](2+/3+) complex as the electron-transfer mediator. The biocatalyst was immobilized in this low-potential redox polymer on a carbon electrode. Upon the addition of sulfite to the immobilized separate Moco domain, the generation of a significant catalytic current demonstrated that the catalytic center is effectively wired and active. The bioelectrocatalytic current of the wired separate catalytic domain reached 25\% of the signal of the wired full molybdoheme enzyme hSO, in which the heme b(5) is involved in the electron-transfer pathway. This is the first report on a catalytically active wired molybdenum cofactor domain. The formal potential of this electrochemical mediator is between the potentials of the two cofactors of hSO, and as hSO can occupy several conformations in the polymer matrix, it is imaginable that electron transfer from the catalytic site to the electrode through the osmium center occurs for the hSO molecules in which the Moco domain is sufficiently accessible. The observation of catalytic oxidation currents at low potentials is favorable for applications in bioelectronic devices.}, language = {en} } @article{YarmanGroebeNeumannetal.2012, author = {Yarman, Aysu and Gr{\"o}be, Glenn and Neumann, Bettina and Kinne, Mathias and Gajovic-Eichelmann, Nenad and Wollenberger, Ursula and Hofrichter, Martin and Ullrich, Rene and Scheibner, Katrin and Scheller, Frieder W.}, title = {The aromatic peroxygenase from Marasmius rutola-a new enzyme for biosensor applications}, series = {Analytical \& bioanalytical chemistry}, volume = {402}, journal = {Analytical \& bioanalytical chemistry}, number = {1}, publisher = {Springer}, address = {Heidelberg}, issn = {1618-2642}, doi = {10.1007/s00216-011-5497-y}, pages = {405 -- 412}, year = {2012}, abstract = {The aromatic peroxygenase (APO; EC 1.11.2.1) from the agraric basidomycete Marasmius rotula (MroAPO) immobilized at the chitosan-capped gold-nanoparticle-modified glassy carbon electrode displayed a pair of redox peaks with a midpoint potential of -278.5 mV vs. AgCl/AgCl (1 M KCl) for the Fe(2+)/Fe(3+) redox couple of the heme-thiolate-containing protein. MroAPO oxidizes aromatic substrates such as aniline, p-aminophenol, hydroquinone, resorcinol, catechol, and paracetamol by means of hydrogen peroxide. The substrate spectrum overlaps with those of cytochrome P450s and plant peroxidases which are relevant in environmental analysis and drug monitoring. In M. rotula peroxygenase-based enzyme electrodes, the signal is generated by the reduction of electrode-active reaction products (e.g., p-benzoquinone and p-quinoneimine) with electro-enzymatic recycling of the analyte. In these enzyme electrodes, the signal reflects the conversion of all substrates thus representing an overall parameter in complex media. The performance of these sensors and their further development are discussed.}, language = {en} } @article{PengUteschYarmanetal.2015, author = {Peng, Lei and Utesch, Tillmann and Yarman, Aysu and Jeoung, Jae-Hun and Steinborn, Silke and Dobbek, Holger and Mroginski, Maria Andrea and Tanne, Johannes and Wollenberger, Ursula and Scheller, Frieder W.}, title = {Surface-Tuned Electron Transfer and Electrocatalysis of Hexameric Tyrosine-Coordinated Heme Protein}, series = {Chemistry - a European journal}, volume = {21}, journal = {Chemistry - a European journal}, number = {20}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201405932}, pages = {7596 -- 7602}, year = {2015}, abstract = {Molecular modeling, electrochemical methods, and quartz crystal microbalance were used to characterize immobilized hexameric tyrosine-coordinated heme protein (HTHP) on bare carbon or on gold electrodes modified with positively and negatively charged self-assembled monolayers (SAMs), respectively. HTHP binds to the positively charged surface but no direct electron transfer (DET) is found due to the long distance of the active sites from the electrode surfaces. At carboxyl-terminated surfaces, the neutrally charged bottom of HTHP can bind to the SAM. For this "disc" orientation all six hemes are close to the electrode and their direct electron transfer should be efficient. HTHP on all negatively charged SAMs showed a quasi-reversible redox behavior with rate constant k(s) values between 0.93 and 2.86 s(-1) and apparent formal potentials E-app(0)' between -131.1 and -249.1 mV. On the MUA/MU-modified electrode, the maximum surface concentration corresponds to a complete monolayer of the hexameric HTHP in the disc orientation. HTHP electrostatically immobilized on negatively charged SAMs shows electrocatalysis of peroxide reduction and enzymatic oxidation of NADH.}, language = {en} } @article{ChenWollenbergerLisdatetal.2000, author = {Chen, Jian and Wollenberger, Ursula and Lisdat, Fred and Ge, Bixia and Scheller, Frieder W.}, title = {Superoxide sensor based on hemin modified electrode}, year = {2000}, language = {en} } @article{SpricigoRichterLeimkuehleretal.2010, author = {Spricigo, Roberto and Richter, Claudia and Leimk{\"u}hler, Silke and Gorton, Lo and Scheller, Frieder W. and Wollenberger, Ursula}, title = {Sulfite biosensor based on osmium redox polymer wired sulfite oxidase}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2009.09.001}, year = {2010}, abstract = {A biosensor, based on a redoxactive osmium polymer and sulfite oxidase on screen-printed electrodes, is presented here as a promising method for the detection of sulfite. A catalytic oxidative current was generated when a sample containing sulfite was pumped over the carbon screen-printed electrode modified with osmium redox polymer wired sulfite oxidase. A stationary value was reached after approximately 50 s and a complete measurement lasted no more than 3 min. The electrode polarized at -0.1 V (vs. Ag vertical bar AgCl 1M KCl) permits minimizing the influence of interfering substances, since these compounds can be unspecific oxidized at higher potentials. Because of the good stability of the protein film on the electrode surface, a well functioning biosensor-flow system was possible to construct. The working stability and reproducibility were further enhanced by the addition of bovine serum albumin generating a more long-term stable and biocompatible protein environment. The optimized biosensor showed a stable signal for more than a week of operation and a coefficient of variation of 4.8\% for 12 successive measurements. The lower limit of detection of the sensor was 0.5 mu M sulfite and the response was linear until 100 mu M. The high sensitivity permitted a 1:500 dilution of wine samples. The immobilization procedure and the operational conditions granted minimized interferences. Additionally, repeating the immobilization procedure to form several layers of wired SO further increased the sensitivity of such a sensor. Finally. the applicability of the developed sulfite biosensor was tested on real samples, such as white and red wines.}, language = {en} } @article{KielbSezerKatzetal.2015, author = {Kielb, Patrycja and Sezer, Murat and Katz, Sagie and Lopez, Francesca and Schulz, Christopher and Gorton, Lo and Ludwig, Roland and Wollenberger, Ursula and Zebger, Ingo and Weidinger, Inez M.}, title = {Spectroscopic Observation of Calcium-Induced Reorientation of Cellobiose Dehydrogenase Immobilized on Electrodes and its Effect on Electrocatalytic Activity}, series = {ChemPhysChem : a European journal of chemical physics and physical chemistry}, volume = {16}, journal = {ChemPhysChem : a European journal of chemical physics and physical chemistry}, number = {9}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1439-4235}, doi = {10.1002/cphc.201500112}, pages = {1960 -- 1968}, year = {2015}, abstract = {Cellobiose dehydrogenase catalyzes the oxidation of various carbohydrates and is considered as a possible anode catalyst in biofuel cells. It has been shown that the catalytic performance of this enzyme immobilized on electrodes can be increased by presence of calcium ions. To get insight into the Ca2+-induced changes in the immobilized enzyme we employ surface-enhanced vibrational (SERR and SEIRA) spectroscopy together with electrochemistry. Upon addition of Ca2+ ions electrochemical measurements show a shift of the catalytic turnover signal to more negative potentials while SERR measurements reveal an offset between the potential of heme reduction and catalytic current. Comparing SERR and SEIRA data we propose that binding of Ca2+ to the heme induces protein reorientation in a way that the electron transfer pathway of the catalytic FAD center to the electrode can bypass the heme cofactor, resulting in catalytic activity at more negative potentials.}, language = {en} } @article{BistolasChristensonRuzgasetal.2004, author = {Bistolas, Nikitas and Christenson, A. and Ruzgas, T. and Jung, Christiane and Scheller, Frieder W. and Wollenberger, Ursula}, title = {Spectroelectrochemistry of cytochrome P450cam}, year = {2004}, abstract = {The spectroelectrochemistry of camphor-bound cytochrome P450cam (P450cam) using gold electrodes is described. The electrodes were modified with either 4,4'-dithiodipyridin or sodium dithionite. Electrolysis of P450cam was carried out when the enzyme was in solution, while at the same time UV visible absorption spectra were recorded. Reversible oxidation and reduction could be observed with both 4,4'-dithiodipyridin and dithionite modified electrodes. A formal potential (E-0') of -373 mV vs Ag/AgCl 1 M KCl was determined. The spectra of P450cam complexed with either carbon monoxide or metyrapone, both being inhibitors of P450 catalysis, clearly indicated that the protein retained its native state in the electrochemical cell during electrolysis. (C) 2003 Elsevier Inc. All rights reserved}, language = {en} } @article{HalamekWollenbergerStoeckleinetal.2007, author = {Hal{\´a}mek, Jan and Wollenberger, Ursula and St{\"o}cklein, Walter F. M. and Warsinke, Axel and Scheller, Frieder W.}, title = {Signal amplification in immunoassays using labeling via boronic acid binding to the sugar moiety of immunoglobulin G : proof of concept for glycated hemoglobin}, issn = {0003-2719}, doi = {10.1080/00032710701327096}, year = {2007}, abstract = {A novel electrochemical immunoassay based on the multiple affinity labeling of the indicator antibody with an electro-active tag is presented. The concept is illustrated for the determination of the glycated hemoglobin HbA1c in hemoglobin samples. Hemoglobin is adsorbed to the surfactant-modified surface of a piezoelectric quartz crystal. Whereas the quartz crystal nanobalance is used to validate the total Hb binding, the HbA1c on the sensor surface is recognized by an antibody and quantified electrochemically after the sugar moieties of the antibody have been labeled in-situ with ferroceneboronic acid. The sensitivity of this sensor is about threefold higher than the sensitivity of a hemoglobin sensor, where the ferroceneboronic acid is bound directly to HbA1c.}, language = {en} } @article{LisdatWollenbergerPaeschkeetal.1998, author = {Lisdat, Fred and Wollenberger, Ursula and Paeschke, Manfred and Scheller, Frieder W.}, title = {Sensitive catecholamine measurement using a monoenzymatic recycling system}, year = {1998}, language = {en} } @article{SarauliRiedelWettsteinetal.2012, author = {Sarauli, David and Riedel, Marc and Wettstein, Christoph and Hahn, Robert and Stiba, Konstanze and Wollenberger, Ursula and Leimk{\"u}hler, Silke and Schmuki, Patrik and Lisdat, Fred}, title = {Semimetallic TiO2 nanotubes new interfaces for bioelectrochemical enzymatic catalysis}, series = {Journal of materials chemistry}, volume = {22}, journal = {Journal of materials chemistry}, number = {11}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {0959-9428}, doi = {10.1039/c2jm16427b}, pages = {4615 -- 4618}, year = {2012}, abstract = {Different self-organized TiO2 nanotube structures are shown to represent new interfaces for the achievement of bioelectrochemical enzymatic catalysis involving redox proteins and enzymes without further surface modification or the presence of mediators.}, language = {en} } @article{ZengFrascaRumschoetteletal.2016, author = {Zeng, Ting and Frasca, Stefano and Rumsch{\"o}ttel, Jens and Koetz, Joachim and Leimk{\"u}hler, Silke and Wollenberger, Ursula}, title = {Role of Conductive Nanoparticles in the Direct Unmediated Bioelectrocatalysis of Immobilized Sulfite Oxidase}, series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, volume = {28}, journal = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1040-0397}, doi = {10.1002/elan.201600246}, pages = {2303 -- 2310}, year = {2016}, language = {en} } @article{SchellerWollenbergerWarsinkeetal.2001, author = {Scheller, Frieder W. and Wollenberger, Ursula and Warsinke, Axel and Lisdat, Fred}, title = {Research and development in biosensors}, year = {2001}, language = {en} } @article{SezerSpricigoUteschetal.2010, author = {Sezer, Murat and Spricigo, Roberto and Utesch, Tillmann and Millo, Diego and Leimk{\"u}hler, Silke and Mroginski, Maria A. and Wollenberger, Ursula and Hildebrandt, Peter and Weidinger, Inez M.}, title = {Redox properties and catalytic activity of surface-bound human sulfite oxidase studied by a combined surface enhanced resonance Raman spectroscopic and electrochemical approach}, issn = {1463-9076}, doi = {10.1039/B927226g}, year = {2010}, abstract = {Human sulfite oxidase (hSO) was immobilised on SAM-coated silver electrodes under preservation of the native heme pocket structure of the cytochrome b5 (Cyt b5) domain and the functionality of the enzyme. The redox properties and catalytic activity of the entire enzyme were studied by surface enhanced resonance Raman (SERR) spectroscopy and cyclic voltammetry (CV) and compared to the isolated heme domain when possible. It is shown that heterogeneous electron transfer and catalytic activity of hSO sensitively depend on the local environment of the enzyme. Increasing the ionic strength of the buffer solution leads to an increase of the heterogeneous electron transfer rate from 17 s(-1) to 440 s(- 1) for hSO as determined by SERR spectroscopy. CV measurements demonstrate an increase of the apparent turnover rate for the immobilised hSO from 0.85 s(-1) in 100 mM buffer to 5.26 s(-1) in 750 mM buffer. We suggest that both effects originate from the increased mobility of the surface-bound enzyme with increasing ionic strength. In agreement with surface potential calculations we propose that at high ionic strength the enzyme is immobilised via the dimerisation domain to the SAM surface. The flexible loop region connecting the Moco and the Cyt b5 domain allows alternating contact with the Moco interaction site and the SAM surface, thereby promoting the sequential intramolecular and heterogeneous electron transfer from Moco via Cyt b5 to the electrode. At lower ionic strength, the contact time of the Cyt b5 domain with the SAM surface is longer, corresponding to a slower overall electron transfer process.}, language = {en} } @article{LisdatHoWollenbergeretal.1998, author = {Lisdat, Fred and Ho, Wah O. and Wollenberger, Ursula and Scheller, Frieder W. and Richter, Torsten and Bilitewski, Ursula}, title = {Recycling systems based on screen-printed electrodes}, year = {1998}, language = {en} }