@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} }