@article{WollenbergerScheller1993,
  author    = {Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Enzyme activation for activator and enzyme activity measurement},
  year      = {1993},
  language  = {en}
}
@article{WollenbergerNeumannScheller1993,
  author    = {Wollenberger, Ursula and Neumann, B. and Scheller, Frieder W.},
  title     = {Enzyme and microbial sensors for environmental Monitoring},
  year      = {1993},
  language  = {en}
}
@article{SchellerWollenbergerSchubertetal.1993,
  author    = {Scheller, Frieder W. and Wollenberger, Ursula and Schubert, Florian and Pfeiffer, Dorothea and Markower, Alexander and McNeil, C. J.},
  title     = {Multienzyme biosensors : coupled enzyme reactions and enzyme activation},
  year      = {1993},
  language  = {en}
}
@article{WollenbergerSchubertPfeifferetal.1993,
  author    = {Wollenberger, Ursula and Schubert, Florian and Pfeiffer, Dorothea and Scheller, Frieder W.},
  title     = {Enhancing biosensor performance using multienzyme systems},
  year      = {1993},
  language  = {en}
}
@article{WollenbergerNeumannRiedeletal.1994,
  author    = {Wollenberger, Ursula and Neumann, B. and Riedel, K. and Scheller, Frieder W.},
  title     = {Enzyme and microbial sensors for phosphate, phenols, pesticides and peroxides},
  year      = {1994},
  language  = {en}
}
@article{PaeschkeWollenbergerUhligetal.1995,
  author    = {Paeschke, Manfred and Wollenberger, Ursula and Uhlig, A. and Schnakenberg, Uwe and Wagner, B. and Hintsche, R.},
  title     = {A stacked multichannel amperometric detection system},
  year      = {1995},
  language  = {en}
}
@article{PaeschkeWollenbergerKoehleretal.1995,
  author    = {Paeschke, Manfred and Wollenberger, Ursula and K{\"o}hler, C. and Lisec, T. and Schnakenberg, Uwe and Wagner, B.},
  title     = {Properties of interdigital electrode arrays with different geometries},
  year      = {1995},
  language  = {en}
}
@article{PaeschkeHintscheWollenbergeretal.1995,
  author    = {Paeschke, Manfred and Hintsche, Rainer and Wollenberger, Ursula and Jin, Wen and Scheller, Frieder W.},
  title     = {Dynamic redox recycling of cytochrome c},
  issn      = {0022-0728},
  year      = {1995},
  language  = {en}
}
@article{WollenbergerHintscheScheller1995,
  author    = {Wollenberger, Ursula and Hintsche, R. and Scheller, Frieder W.},
  title     = {Biosensors for analytical microsystems},
  year      = {1995},
  language  = {en}
}
@article{Wollenberger1995,
  author    = {Wollenberger, Ursula},
  title     = {Electrochemical biosensors - ways to improve sensor performance},
  year      = {1995},
  language  = {en}
}
@article{SchellerMakowerGhindilisetal.1995,
  author    = {Scheller, Frieder W. and Makower, Alexander and Ghindilis, A. L. and Bier, Frank Fabian and Ehrentreich-F{\"o}rster, Eva and Wollenberger, Ursula and Bauer, Christian G. and Micheel, Burkhard and Pfeiffer, Dorothea and Szeponik, Jan and Michael, N. and Kaden, H.},
  title     = {Enzyme sensors for subnanomolar concentrations},
  year      = {1995},
  language  = {en}
}
@article{JinWollenbergerBieretal.1995,
  author    = {Jin, Wen and Wollenberger, Ursula and Bier, Frank Fabian and Scheller, Frieder W.},
  title     = {Construction and characterization of multi-layer-enzyme electrode : covalent binding of quinoprotein glucose dehydrogenase onto gold electrodes},
  year      = {1995},
  language  = {en}
}
@article{SchellerPfeifferSchubertetal.1995,
  author    = {Scheller, Frieder W. and Pfeiffer, Dorothea and Schubert, Florian and Wollenberger, Ursula},
  title     = {Enzyme - based electrodes},
  year      = {1995},
  language  = {en}
}
@article{WollenbergerDrungilieneStoeckleinetal.1996,
  author    = {Wollenberger, Ursula and Drungiliene, A. and St{\"o}cklein, Walter F. M. and Kulys, J. and Scheller, Frieder W.},
  title     = {Direct electrocatalytic determination of dissolved peroxidases},
  year      = {1996},
  language  = {en}
}
@article{KaishevaIlievKazarevaetal.1996,
  author    = {Kaisheva, A. and Iliev, I. and Kazareva, R. and Christov, S. and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Enzyme/gas diffusion electrodes for determination of phenol},
  year      = {1996},
  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{WelzelKossmehlEngelmannetal.1996,
  author    = {Welzel, H.-P. and Kossmehl, G. and Engelmann, G. and Neumann, B. and Wollenberger, Ursula and Scheller, Frieder W. and Schr{\"o}der, W.},
  title     = {Reactive groups on polymer covered electrodes, 4. Lactate-oxidase-biosensor based on electrodes modifies by polyphiophene},
  year      = {1996},
  language  = {en}
}
@article{PfeifferSchubertWollenbergeretal.1996,
  author    = {Pfeiffer, Dorothea and Schubert, Frank and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Electrochemical sensors : enzyme electrodes and field effect transistors},
  year      = {1996},
  language  = {en}
}
@article{JinWollenbergerBieretal.1996,
  author    = {Jin, Wen and Wollenberger, Ursula and Bier, Frank Fabian and Makower, Alexander and Schiller, Frieder W.},
  title     = {Electron transfer between cytochrome c and copper enzymes},
  year      = {1996},
  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{WollenbergerSchubertPfeifferetal.1996,
  author    = {Wollenberger, Ursula and Schubert, Florian and Pfeiffer, Dorothea and Scheller, Frieder W.},
  title     = {Recycling sensors based on kinases : proceedings of Mosbach Symposion on Biochemical Technology},
  year      = {1996},
  language  = {en}
}
@article{SchellerWollenbergerPfeifferetal.1996,
  author    = {Scheller, Frieder W. and Wollenberger, Ursula and Pfeiffer, Dorothea and Schubert, Florian},
  title     = {Overview of biosensor technology : proceedings of Mosbach Symposion on Biochemical Technology},
  year      = {1996},
  language  = {en}
}
@article{PeterWollenberger1997,
  author    = {Peter, Martin G. and Wollenberger, Ursula},
  title     = {Phenol-oxidizing enzymes : mechanisms and applications},
  year      = {1997},
  language  = {en}
}
@article{WollenbergerLisdatScheller1997,
  author    = {Wollenberger, Ursula and Lisdat, Fred and Scheller, Frieder W.},
  title     = {Enzymatic substrade recycling electrodes},
  year      = {1997},
  language  = {en}
}
@article{XieTangWollenbergeretal.1997,
  author    = {Xie, B. and Tang, X. and Wollenberger, Ursula and Johansson, G. and Gorton, Lo and Scheller, Frieder W. and Danielsson, B.},
  title     = {Hybrid biosensor for simultaneous electrochemical and thermal detection},
  year      = {1997},
  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{MarkowerWollenbergerHoertnageletal.1997,
  author    = {Markower, Alexander and Wollenberger, Ursula and H{\"o}rtnagel, H. and Pfeiffer, Dorothea and Scheller, Frieder W.},
  title     = {Catecholamine detection using enzymatic amplification},
  year      = {1997},
  language  = {en}
}
@article{WelzelKossmehlEngelmannetal.1997,
  author    = {Welzel, H.-P. and Kossmehl, G. and Engelmann, G. and Neumann, B. and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Electrochemical polymerization of functionalized thiohene derivatives for immobilization of proteins},
  year      = {1997},
  language  = {en}
}
@article{WollenbergerNeumann1997,
  author    = {Wollenberger, Ursula and Neumann, B.},
  title     = {Quinoprotein glucose dehydrogenase modified carbon paste electrode for detection of phenolic compounds},
  year      = {1997},
  language  = {en}
}
@article{KatterleWollenbergerScheller1997,
  author    = {Katterle, Martin and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Electrochemistry of hemoglobin at modified silver electrodes is not a redox-process of iron protoporhyrin IX},
  year      = {1997},
  language  = {en}
}
@article{KulysDrungilieneWollenbergeretal.1997,
  author    = {Kulys, J. and Drungiliene, A. and Wollenberger, Ursula and Krikstopaitis, K. and Scheller, Frieder W.},
  title     = {Electroanalytical determination of peroxidases and laccases on carbon paste electrodes},
  year      = {1997},
  language  = {en}
}
@article{JinWollenbergerKaergeletal.1997,
  author    = {Jin, Wen and Wollenberger, Ursula and K{\"a}rgel, E. and Schunck, W.-H. and Scheller, Frieder W.},
  title     = {Electrochemical investigation of the intermolecular electron transfer between cytochrome c and NADPH-cytochrome P450-reductase},
  year      = {1997},
  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{KulysDrungilieneWollenbergeretal.1998,
  author    = {Kulys, J. and Drungiliene, A. and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Membrane covered carbon paste electrode for the electrochemical determination of perioxidase and microperoxidase in a flow system},
  year      = {1998},
  language  = {en}
}
@article{WollenbergerNeumannScheller1998,
  author    = {Wollenberger, Ursula and Neumann, B. and Scheller, Frieder W.},
  title     = {Development of a biomimetic alkane sensor f},
  year      = {1998},
  language  = {en}
}
@article{LehmannWollenbergerBrigeliusFloheetal.1998,
  author    = {Lehmann, Claudia and Wollenberger, Ursula and Brigelius-Floh{\´e}, Regina and Scheller, Frieder W.},
  title     = {Bioelectrocatalysis by a selenoenzyme},
  year      = {1998},
  language  = {en}
}
@article{JinWollenbergerScheller1998,
  author    = {Jin, Wen and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {PQQ as redox shuttle for quinoprotein glucose dehydrogenase},
  year      = {1998},
  language  = {en}
}
@article{StrefferKaatzBaueretal.1998,
  author    = {Streffer, Katrin and Kaatz, Helvi and Bauer, Christian G. and Makower, Alexander and Schulmeister, Thomas and Scheller, Frieder W. and Peter, Martin G. and Wollenberger, Ursula},
  title     = {Application of a sensitive catechol detector for determination of tyrosinase inhibitors},
  year      = {1998},
  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}
}
@article{SchellerKleinjungBieretal.1998,
  author    = {Scheller, Frieder W. and Kleinjung, Frank and Bier, Frank Fabian and Markower, Alexander and Neumann, Barbara and Wollenberger, Ursula and Kurochkin, Iliya N. and Eremenko, Arkadi V. and Barmin, Anatoli V. and Klußmann, Sven and F{\"u}rste, Jens-Peter and Erdmann, Volker A. and Mansuy, D.},
  title     = {New recognition elements in biosensing},
  year      = {1998},
  language  = {en}
}
@article{KaatzStrefferWollenbergeretal.1999,
  author    = {Kaatz, Helvi and Streffer, Katrin and Wollenberger, Ursula and Peter, Martin G.},
  title     = {Inhibition of mushroom tyrosinase by kojic acid octanoates},
  year      = {1999},
  language  = {en}
}
@article{SchellerJinEhrentreichFoersteretal.1999,
  author    = {Scheller, Frieder W. and Jin, Wen and Ehrentreich-F{\"o}rster, Eva and Ge, Bixia and Lisdat, Fred and B{\"u}ttemeyer, R. and Wollenberger, Ursula},
  title     = {Cytochrome c based superoxide sensor for in vivo application},
  year      = {1999},
  language  = {en}
}
@article{LeiLisdatWollenbergeretal.1999,
  author    = {Lei, Chenghong and Lisdat, Fred and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Cytochrome c : Clay-modified electrode},
  year      = {1999},
  language  = {en}
}
@article{FridmanWollenbergerBogdanovskayaetal.2000,
  author    = {Fridman, Vadim and Wollenberger, Ursula and Bogdanovskaya, V. A. and Lisdat, Fred and Ruzgas, T. and Lindgren, A. and Gorton, Lo and Scheller, Frieder W.},
  title     = {Electrochemical investigation of cellobiose oxidation by cellobiose dehydrogenase in the presence of cytochrome c as mediator},
  year      = {2000},
  language  = {en}
}
@article{LeiWollenbergerScheller2000,
  author    = {Lei, Chenghong and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Clay based direct electrochemistry of myoglobin},
  year      = {2000},
  language  = {en}
}
@article{LeiWollenbergerJungetal.2000,
  author    = {Lei, Chenghong and Wollenberger, Ursula and Jung, Christiane and Scheller, Frieder W.},
  title     = {Clay-bridged electron transfer between cytochrome P450(cam) and electrode},
  year      = {2000},
  language  = {en}
}
@article{GeMeyerSchoeningetal.2000,
  author    = {Ge, Bixia and Meyer, T. and Sch{\"o}ning, M. J. and Wollenberger, Ursula and Lisdat, Fred},
  title     = {Cytochrome c from chromatium vinosum on gold electrodes},
  year      = {2000},
  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{VijgenboomVijgenboomTeppneretal.2001,
  author    = {Vijgenboom, E. and Vijgenboom, E. and Teppner, A. W. J. W. and Makower, Alexander and Scheller, Frieder W. and Canters, Gerard W. and Wollenberger, Ursula},
  title     = {Determination of phenolic compounds using recombinant tyrosinanse from Streptomyces antibioticus},
  year      = {2001},
  language  = {en}
}
@article{RosePfeifferSchelleretal.2001,
  author    = {Rose, Andreas and Pfeiffer, Dorothea and Scheller, Frieder W. and Wollenberger, Ursula},
  title     = {Quinoprotein glucose dehydrogenasemodified thick-film electrodes for the amperometric detection of phenolic compounds in flow injection analysis},
  year      = {2001},
  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{LehmannWollenbergerBrigeliusFloheetal.2001,
  author    = {Lehmann, Claudia and Wollenberger, Ursula and Brigelius-Floh{\´e}, Regina and Scheller, Frieder W.},
  title     = {Modified gold electrodes for electrochemical studies of the reaction phospholipid hydroperoxide glutathione peroxidas with glutathione and glutathione disulfide},
  year      = {2001},
  language  = {en}
}
@article{SchellerBauerMarkoweretal.2001,
  author    = {Scheller, Frieder W. and Bauer, Christian G. and Markower, Alexander and Wollenberger, Ursula and Warsinke, Axel and Bier, Frank Fabian},
  title     = {Coupling of immunoassays with enzymatic recycling electrodes},
  year      = {2001},
  language  = {en}
}
@article{NistorOsvikDavidssonetal.2002,
  author    = {Nistor, C. and Osvik, A. and Davidsson, R. and Rose, Andreas and Wollenberger, Ursula and Pfeiffer, Dorothea and Emneus, J. and Fiksdal, L.},
  title     = {Detection of escherichia coli water by culture-based amperometric and luminometric methods},
  year      = {2002},
  language  = {en}
}
@article{NistorRoseFarreetal.2002,
  author    = {Nistor, C. and Rose, Andreas and Farre, M. and Stoica, L. and Wollenberger, Ursula and Ruzgas, T. and Pfeiffer, Dorothea and Barcelo, Damia and Gorton, Lo and Emneus, J.},
  title     = {In-field monitoring of cleaning efficiency in waste water treatment plants using two phenolsensitive biosensors},
  year      = {2002},
  language  = {en}
}
@article{LeiWollenbergerBistolasetal.2002,
  author    = {Lei, Chenghong and Wollenberger, Ursula and Bistolas, Nikitas and Guiseppi-Eli, A. and Scheller, Frieder W.},
  title     = {Electron transfer of hemoglobin at electrodes modified with colloidal clay nanoparticles},
  year      = {2002},
  language  = {en}
}
@article{SchellerWollenbergerLeietal.2002,
  author    = {Scheller, Frieder W. and Wollenberger, Ursula and Lei, Chenghong and Jin, Wen and Ge, Bixia and Lehmann, Claudia and Lisdat, Fred and Fridman, Vadim},
  title     = {Bioelectrocatalysis by redox enzymes at modified electrodes},
  year      = {2002},
  language  = {en}
}
@article{SchellerBauerMakoweretal.2002,
  author    = {Scheller, Frieder W. and Bauer, Christian G. and Makower, Alexander and Wollenberger, Ursula and Warsinke, Axel and Bier, Frank Fabian},
  title     = {Immunoassays using enzymatic amplification electrodes},
  isbn      = {0-7484-0791-X},
  year      = {2002},
  language  = {en}
}
@article{RohnRawelWollenbergeretal.2003,
  author    = {Rohn, Sascha and Rawel, Harshadrai Manilal and Wollenberger, Ursula and Kroll, J{\"u}rgen},
  title     = {Enzyme acitivity of alpha-chymotrypsin after derivatization with phenolic compounds},
  year      = {2003},
  language  = {en}
}
@article{MakWollenbergerSchelleretal.2003,
  author    = {Mak, Karen K. W. and Wollenberger, Ursula and Scheller, Frieder W. and Renneberg, Reinhard},
  title     = {An amperometric bi-enzyme sensor for determination of formate using cofactor regeneration},
  year      = {2003},
  language  = {en}
}
@article{SchellerWollenberger2003,
  author    = {Scheller, Frieder W. and Wollenberger, Ursula},
  title     = {Enzyme Electrodes},
  isbn      = {3-527-30401-0},
  year      = {2003},
  language  = {en}
}
@article{ChenStoeckleinSchelleretal.2003,
  author    = {Chen, Jian and St{\"o}cklein, Walter F. M. and Scheller, Frieder W. and Wollenberger, Ursula},
  title     = {Electrochemical determination of human hemoglobin by using ferrocene carboxylic acid modified carbon powder microelectrode},
  year      = {2003},
  language  = {en}
}
@article{KroeningSchellerWollenbergeretal.2004,
  author    = {Kr{\"o}ning, Steffen and Scheller, Frieder W. and Wollenberger, Ursula and Lisdat, Fred},
  title     = {Myoglobin-Clay Electrode for Nitric Oxide (NO) Detection in Solution},
  year      = {2004},
  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{KulysKrikstopaitisSchelleretal.2004,
  author    = {Kulys, J. and Krikstopaitis, K. and Scheller, Frieder W. and Wollenberger, Ursula},
  title     = {Electrochemical parameters of phenoxazine derivatives in solution and at monolayer-modified gold electrodes},
  year      = {2004},
  abstract  = {Electrochemical properties of beta-(10-phenoxazinyl) propylamine (APPX) and beta-(10-phenoxazinyl) propionic acid (PPX) have been studied in solution, and in immobilized state on gold electrodes modified with monolayers of cystamine and mercaptoundecanoic acid. A reversible diffusion-controlled process of APPX and PPX was observed at a bare gold electrode. The electrochemical conversion of both compounds at modified gold electrodes was a quasireversible diffusion-controlled process. The redox potential of immobilized APPX (443 mV) was similar to the potential in solution, while the value of the immobilized PPX was 131 mV higher than in solution. The immobilized mediators were electrocatalytically active in the fungal peroxidase-catalyzed hydrogen peroxide reduction},
  language  = {en}
}
@article{LoewSchellerWollenberger2004,
  author    = {Loew, Noya and Scheller, Frieder W. and Wollenberger, Ursula},
  title     = {Characterization of self-assembling of glucose dehydrogenase in mono- and multilayers on gold electrodes},
  year      = {2004},
  abstract  = {Glucose dehydrogenase (GDH) was assembled electrostatically onto QCM-gold electrodes by their sequential deposition with anionic polyelectrolytes such as PSS and PASA. For the layer-by-layer arrangements both the microgravimetric and the electrochemical sensor signal were followed. Increasing amounts of GDH were deposited by stepwise formation of alternating layers of GDH and PSS or PASA. The mass increase was about 1.88 mug/cm(2) for one GDH/ PASA bilayer and 2.4 mug/cm(2) for a GDH/PSS bilayer. The addition of phenolic compounds resulted in an oxidation current, which could be catalytically increased by the GDH catalysed reaction in the presence of glucose. The system functions as glucose sensor when quinones are present in nonlimiting amount. The amperometric response was already diffusion limited when a single layer of GDH was adsorbed. The sensor sensitivity increased by a factor of 10 when MSA was used instead of MUA as initial electrode modifier},
  language  = {en}
}
@article{ShumyantsevaIvanovBistolasetal.2004,
  author    = {Shumyantseva, V. V. and Ivanov, Y. D. and Bistolas, Nikitas and Scheller, Frieder W. and Archakov, Alexander I. and Wollenberger, Ursula},
  title     = {Direct electron transfer of cytochrome P450 2B4 at electrodes modified with non-ionic detergent and colloidal clay nanoparticles},
  year      = {2004},
  abstract  = {A method for construction of biosensors with membranous cytochrome P450 isoenzymes was developed based on clay/ detergent/protein mixed films. Thin films of sodium montmorillonite colloid with incorporated cytochrome P450 2134 (CYP2B4) with nonionic detergent were prepared on glassy carbon electrodes. The modified electrodes were electrochemically characterized, and bio-electrocatalytic reactions were followed. CYP2B4 can be reduced fast on clay- modified glassy carbon electrodes in the presence of the nonionic detergent Tween 80. In anaerobic solutions, reversible oxidation and reduction is obtained with a formal potential between -0.292 and - 0.305 V vs Ag/AgCl 1 M KCl depending on the preparation of the biosensor. In air-saturated solution, bio-electrocatalytic reduction currents can be obtained with the CYP2B4-modified electrode on addition of typical substrates such as aminopyrine and benzphetamine. This reaction was suppressed when methyrapone, an inhibitor of P450 reactions, was present. Measurement of product formation also indicates the bioelectrocatialysis by CYP2B4},
  language  = {en}
}
@article{BistolasWollenbergerJungetal.2005,
  author    = {Bistolas, Nikitas and Wollenberger, Ursula and Jung, Christiane and Scheller, Frieder W.},
  title     = {Cytochrome P450 biosensors : a review},
  year      = {2005},
  abstract  = {Cytochrome P450 (CYP) is a large family of enzymes containing heme as the active site. Since their discovery and the elucidation of their structure, they have attracted the interest of scientist for many years, particularly due to their catalytic abilities. Since the late 1970s attempts have concentrated on the construction and development of electrochemical sensors. Although sensors based on mediated electron transfer have also been constructed, the direct electron transfer approach has attracted most of the interest. This has enabled the investigation of the electrochemical properties of the various isoforms of CYP. Furthermore, CYP utilized to construct biosensors for the determination of substrates important in environmental monitoring, pharmaceutical industry and clinical practice. (c) 2004 Elsevier B. V. All rights reserved},
  language  = {en}
}
@article{SchellerLisdatWollenberger2005,
  author    = {Scheller, Frieder W. and Lisdat, Fred and Wollenberger, Ursula},
  title     = {Application of electrically contacted enzymes for biosensors},
  isbn      = {3-527- 30690-0},
  year      = {2005},
  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{LiuWollenbergerHalameketal.2005,
  author    = {Liu, Songqin and Wollenberger, Ursula and Halamek, Jan and Leupold, Eik and St{\"o}cklein, Walter F. M. and Warsinke, Axel and Scheller, Frieder W.},
  title     = {Affinity interaction betwen phenylboronic acid-carrying self-assembled monolayers and FAD or HRP},
  year      = {2005},
  abstract  = {A method is provided for the recognition of glycated molecules based on their binding affinities to boronate- carrying monolayers. The affinity interaction of flavin adenine dinucleotide (FAD) and horseradish peroxidase (HRP) with phenylboronic acid monolayers on gold was investigated by using voltammetric and microgravimetric methods. Conjugates of 3-aminopherrylboronic acid and 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) or 11-mercaptoundecanoic acid were prepared and self-assembled on gold surfaces to generate monolayers. FAD is bound to this modified sur-face and recognized by a pair of redox peaks with a formal potential of -0.433 V in a 0.1 m phosphate buffer solution, pH 6.5. Upon addition of a sugar to the buffer, the bound FAD could be replaced, indicating that the binding is reversible. Voltammetric, mass measurements, and photometric activity assays show that the HRP can also be bound to the interface. This binding is reversible, and HRP can be replaced by sorbitol or removed in acidic solution. The effects of pH, incubation time, and concentration of H2O2 were studied by comparing the catalytic reduction of H2O2 in the presence of the electron-donor thionine. The catalytic current of the HRP-loaded electrode was proportional to HRP concentrations in the incubation solution in the range between 5 mu g mL(-1) and 0.4 mg mL(-1) with a linear slope of 3.34 mu A mL mg(-1) and a correlation coefficient of 0.9945},
  language  = {en}
}
@article{LiuWollenbergerKatterleetal.2006,
  author    = {Liu, Songqin and Wollenberger, Ursula and Katterle, Martin and Scheller, Frieder W.},
  title     = {Ferroceneboronic acid-based amperometric biosensor for glycated hemoglobin},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2005.07.011},
  year      = {2006},
  abstract  = {An amperometric biosensor for the determination of glycated hemoglobin in human whole blood is proposed. The principle is based on the electrochemical measurement of ferroceneboronic acid (FcBA) that has been specifically bound to the glycated N-terminus. Hemoglobin is immobilized on a zirconium dioxide nanoparticle modified pyrolytic graphite electrode (PGE) in the presence of didodecyldimethylammonium bromide (DDAB). The incubation of this sensor in FcBA solution leads to the formation of an FcBA-modified surface due to the affinity interaction between boronate and the glycated sites of the hemoglobin. The binding of FcBA results in well-defined redox peaks with an E-0' of 0.299 V versus Ag/AgCl (1 M KCl). The square wave voltammetric response of the bound FcBA reflects the amount of glycated hemoglobin at the surface. This signal increases linearily with the degree of glycated hemoglobin from 6.8 to 14.0\% of total immobilized hemoglobin. The scheme was applied to the determination of the fraction of glycated hemoglobin in whole blood samples.},
  language  = {en}
}
@article{LoewBogdanoffHerrmannetal.2006,
  author    = {Loew, Noya and Bogdanoff, Peter and Herrmann, Iris and Wollenberger, Ursula and Scheller, Frieder W. and Katterle, Martin},
  title     = {Influence of modifications on the efficiency of pyrolysed CoTMPP as electrode material for horseradish peroxidase and the reduction of hydrogen peroxide},
  series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis},
  volume    = {18},
  journal   = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis},
  number    = {23},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1040-0397},
  doi       = {10.1002/elan.200603664},
  pages     = {2324 -- 2330},
  year      = {2006},
  abstract  = {A tailor-made horseradish peroxidase (HRP) bulk composite electrode was developed on the basis of pyrolyzed cobalt tetramethoxyphenylporphyrin (CoTMPP) by modifying pore size and surface area of the porous carbon material through varying amounts of iron oxalate and sulfur prior to pyrolyzation. The materials were used to immobilize horseradish peroxidase (HRP). These electrodes were characterized in terms of their efficiency to reduce hydrogen peroxide. The heterogeneous electron transfer rate constants of different materials were determined with the rotating disk electrode method and a k(S) (401 +/- 61 s(-1)) exceeding previously reported values for native HRP was found.},
  language  = {en}
}
@article{HalamekWollenbergerStoeckleinetal.2007,
  author    = {Hal{\´a}mek, Jan and Wollenberger, Ursula and St{\"o}cklein, Walter F. M. and Scheller, Frieder W.},
  title     = {Development of a biosensor for glycated hemoglobin},
  issn      = {0013-4686},
  doi       = {10.1016/j.electacta.2007.03.059},
  year      = {2007},
  abstract  = {The development of an electrochemical piezoelectric sensor for the detection of glycated hemoglobin is presented. The total hemoglobin (Hb) content is monitored with a mass-sensitive quartz crystal modified with surfactants, and the glycated fraction of the immobilized Hb is determined by subsequent voltarnmetric measurement of the coupled ferroceneboronic acid. Different modifications of the sensor were tested for their hemoglobin binding ability. Deoxycholate (DOCA) was found to be the most suitable among the examined modifiers. Piezoelectric quartz crystals with gold electrodes were modified with DOCA by covalent binding to a pre-formatted 4-aminothiophenol monolayer. The properties of the Hb binding to DOCA and the pH effect on this interaction were studied. In the proposed assay for glycated hemoglobin at first an Hb sample is incubated with ferroceneboronic acid (FcBA), which binds to the fructosyl residue of the glycated Hb. Then this preincubated Hb sample is allowed to interact with the DOCA-modified piezoelectric quartz crystal. The binding is monitored by quartz crystal nanobalance QCN). The amount of FcBA present on the sensor surface is determined by square wave voltammetry. The binding of FcBA results in well-defined peaks with an EO' of +200 mV versus Ag/AgC1 (1 M KC1). The peak height depends on the degree of glycated Hb in the sample ranging from 0\% to 20\% of total Hb. The regeneration of the sensing surface is achieved by pepsin digestion of the deposited Hb. Thus the sensor can be re-used more than 30 times.},
  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{LoewWollenbergerSchelleretal.2009,
  author    = {Loew, Noya and Wollenberger, Ursula and Scheller, Frieder W. and Katterle, Martin},
  title     = {Direct electrochemistry and spectroelectrochemistry of osmium substituted horseradish peroxidase},
  issn      = {1567-5394},
  doi       = {10.1016/j.bioelechem.2009.03.015},
  year      = {2009},
  abstract  = {In this contribution the substitution of the central protoporphyrin IX iron complex of horseradish peroxidase by the respective osmium porphyrin complex is described. The direct electrochemical reduction of the Os containing horseradish peroxidase (OsHRP) was achieved at ITO and modified glassy carbon electrodes and in combination with spectroscopy revealed the three redox couples (OsHRP)-H-III/(OsHRP)-H-IV, (OsHRP)-H-IV/(OsHRP)-H-V and (OsHRP)-H-V/ (OsHRP)-H-VI. The midpoint potentials differ dependent on the electrode material used with E-1/2 (Os-III/IV) of -0.4 V (ITO) and -0.25 V (GC), E-1/2 (Os-IV/V) of -0.16 V (ITO) and +0.10 V (GC), and E-1/2 (Os-V/VI)of +018 V (ITO), respectively Moreover, with immobilised OsHRP the direct electrocatalytic reduction of hydrogen peroxide and tert-butyl hydroperoxide was observed. In comparison to electrodes modified with native HRP the sensitivity of the OsHRP-electrode for tert-butyl hydroperoxide is higher.},
  language  = {en}
}
@article{SpricigoDronovLisdatetal.2009,
  author    = {Spricigo, Roberto and Dronov, Roman and Lisdat, Fred and Leimk{\"u}hler, Silke and Scheller, Frieder W. and Wollenberger, Ursula},
  title     = {Electrocatalytic sulfite biosensor with human sulfite oxidase co-immobilized with cytochrome c in a polyelectrolyte-containing multilayer},
  issn      = {1618-2642},
  doi       = {10.1007/s00216-008-2432-y},
  year      = {2009},
  abstract  = {An efficient electrocatalytic biosensor for sulfite detection was developed by co-immobilizing sulfite oxidase and cytochrome c with polyaniline sulfonic acid in a layer-by-layer assembly. QCM, UV-Vis spectroscopy and cyclic voltammetry revealed increasing loading of electrochemically active protein with the formation of multilayers. The sensor operates reagentless at low working potential. A catalytic oxidation current was detected in the presence of sulfite at the modified gold electrode, polarized at +0.1 V ( vs. Ag/AgCl 1 M KCl). The stability of the biosensor performance was characterized and optimized. A 17-bilayer electrode has a linear range between 1 and 60 mu M sulfite with a sensitivity of 2.19 mA M-1 sulfite and a response time of 2 min. The electrode retained a stable response for 3 days with a serial reproducibility of 3.8\% and lost 20\% of sensitivity after 5 days of operation. It is possible to store the sensor in a dry state for more than 2 months. The multilayer electrode was used for determination of sulfite in unspiked and spiked samples of red and white wine. The recovery and the specificity of the signals were evaluated for each sample.},
  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{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{FrascavonGrabergFengetal.2010,
  author    = {Frasca, Stefano and von Graberg, Till and Feng, Jiu-Ju and Thomas, Arne and Smarsly, Bernd M. and Weidinger, Inez M. and Scheller, Frieder W. and Hildebrandt, Peter and Wollenberger, Ursula},
  title     = {Mesoporous indium tin oxide as a novel platform for bioelectronics},
  issn      = {1867-3880},
  doi       = {10.1002/cctc.201000047},
  year      = {2010},
  abstract  = {Stable immobilization and reversible electrochemistry of cytochrome c in a tranparent indium tin oxide film with a well-defined mesoporosity (mpITO) is demonstrated. the transparency and good conductivity, in combination with the large surface area of mpITO, allow the incorporation of a high amount of elelctroactive biomolecules and their electrochemical and spectroscopic investigation. UV/Vis and resonance Raman spectroscopy, in combination with direct protein voltammetry are employed for the characterization of cytochrome c immobilized in the mpITO and reveal no perturbant of the structural of the integrity of the redox protein. The potential of this modified material as a biosensor detection of superoxide anions is also demonstrated.},
  language  = {en}
}
@article{KepplingerLisdatWollenberger2011,
  author    = {Kepplinger, Christian and Lisdat, Fred and Wollenberger, Ursula},
  title     = {Cytochrome c/polyelectrolyte multilayers investigated by E-QCM-D - effect of temperature on the assembly structure},
  series = {Langmuir},
  volume    = {27},
  journal   = {Langmuir},
  number    = {13},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/la200860p},
  pages     = {8309 -- 8315},
  year      = {2011},
  abstract  = {Protein multilayers, consisting of cytochrome c (cyt c) and poly(aniline sulfonic acid) (PASA), are investigated by electrochemical quartz crystal microbalance with dissipation monitoring (E-QCM-D). This technique reveals that a four-bilayer assembly has rather rigid properties. A thickness of 16.3 +/- 0.8 nm is calculated with the Sauerbrey equation and is found to be in good agreement with a viscoelastic model. The electroactive amount of cyt c is estimated by the deposited mass under the assumption of 50\% coupled water. Temperature-induced stabilization of the multilayer assembly has been investigated in the temperature range between 30 and 45 degrees C. The treatment results in a loss of material and a contraction of the film. The electroactive amount of cyt c also decreases during heating and remains constant after the cooling period. The contraction of the film is accompanied by the enhanced stability of the assembly. In addition, it is found that cyt c and PASA can be assembled at higher temperatures, resulting in the formation of multilayer systems with less dissipation.},
  language  = {en}
}
@article{WuWollenbergerHofrichteretal.2011,
  author    = {Wu, Yunhua and Wollenberger, Ursula and Hofrichter, Martin and Ullrich, Rene and Scheibner, Katrin and Scheller, Frieder W.},
  title     = {Direct electron transfer of Agrocybe aegerita peroxygenase at electrodes modified with chitosan-capped Au nanoparticles and its bioelectrocatalysis to aniline},
  series = {Sensors and actuators : B, Chemical},
  volume    = {160},
  journal   = {Sensors and actuators : B, Chemical},
  number    = {1},
  publisher = {Elsevier},
  address   = {Lausanne},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2011.09.090},
  pages     = {1419 -- 1426},
  year      = {2011},
  abstract  = {Three different sizes of chitosan-capped Au nanoparticles were synthesized and were used to incorporate Agrocybe aegerita peroxygenase (AaeAPO) onto the surface of glassy carbon electrode. The direct electron transfer of AaeAPO was achieved in all films. The highest amount of electroactive enzyme and highest electron transfer rate constant k(s) of AaeAPO were obtained in the film with the smallest size of chitosan-capped Au nanoparticles. In anaerobic solutions, quasi-reversible oxidation and reduction are obtained with a formal potential of -0.280V vs. Ag/AgCl 1 M KCl in 100 mM (pH 7.0) PBS at scan rate of 1 V s(-1). Bioelectrocatalytic reduction currents can be obtained with the AaeAPO-modified electrode on addition of hydrogen peroxide. This reaction was suppressed when sodium azide, an inhibitor of AaeAPO, was present. Furthermore, the peroxide-dependent conversion of aniline was characterized and it was found that a polymer product via p-aminophenol is formed. And the AaeAPO biosensor was applied to determine aniline and p-aminophenol.},
  language  = {en}
}
@article{YarmanBadalyanGajovicEichelmannetal.2011,
  author    = {Yarman, Aysu and Badalyan, Artavazd and Gajovic-Eichelmann, Nenad and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Enzyme electrode for aromatic compounds exploiting the catalytic activities of microperoxidase-11},
  series = {Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics},
  volume    = {30},
  journal   = {Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics},
  number    = {1},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0956-5663},
  doi       = {10.1016/j.bios.2011.09.004},
  pages     = {320 -- 323},
  year      = {2011},
  abstract  = {Microperoxidase-11 (MR-11) which has been immobilised in a matrix of chitosan-embedded gold nanoparticles on the surface of a glassy carbon electrode catalyzes the conversion of aromatic substances. This peroxide-dependent catalysis of microperoxidase has been applied in an enzyme electrode for the first time to indicate aromatic compounds such as aniline. 4-fluoroaniline, catechol and p-aminophenol. The electrode signal is generated by the cathodic reduction of the quinone or quinoneimine which is formed in the presence of both MP-II and peroxide from the substrate. The same sensor principle will be extended to aromatic drugs.},
  language  = {en}
}
@article{FrascaRichtervonGrabergetal.2011,
  author    = {Frasca, Stefano and Richter, Claudia and von Graberg, Till and Smarsly, Bernd M. and Wollenberger, Ursula},
  title     = {Electrochemical switchable protein-based optical device},
  series = {Engineering in life sciences : Industry, Environment, Plant, Food},
  volume    = {11},
  journal   = {Engineering in life sciences : Industry, Environment, Plant, Food},
  number    = {6},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {1618-0240},
  doi       = {10.1002/elsc.201100079},
  pages     = {554 -- 558},
  year      = {2011},
  abstract  = {The present work contributes to the development of reusable sensing systems with a visual evaluation of the detection process related to an analyte. An electrochemical switchable protein-based optical device was designed with the core part composed of cytochrome c immobilized in a mesoporous indium tin oxide film. A color-developing redox-sensitive dye was used as switchable component of the system. The cytochrome c-catalyzed oxidation of the dye by hydrogen peroxide is spectroscopically investigated. When the dye is co-immobilized with the protein, its redox state is easily controlled by application of an electrical potential at the supporting material. This enables to electrochemically reset the system to the initial state and repetitive signal generation. The implemented reset function of the color forming reaction will make calibration of small test devices possible. The principle can be extended to other color forming redox reactions and to coupled enzyme systems, such as rapid food testing and indication of critical concentrations of metabolites for health care.},
  language  = {en}
}
@article{AksuFrascaWollenbergeretal.2011,
  author    = {Aksu, Yilmaz and Frasca, Stefano and Wollenberger, Ursula and Driess, Matthias and Thomas, Arne},
  title     = {A molecular precursor approach to tunable porous tin-rich indium tin oxide with durable high electrical conductivity for bioelectronic devices},
  series = {Chemistry of materials : a publication of the American Chemical Society},
  volume    = {23},
  journal   = {Chemistry of materials : a publication of the American Chemical Society},
  number    = {7},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0897-4756},
  doi       = {10.1021/cm103087p},
  pages     = {1798 -- 1804},
  year      = {2011},
  abstract  = {The preparation of porous, i.e., high surface area electrodes from transparent conducting oxides, is a valuable goal in materials chemistry as such electrodes can enable further development of optoelectronic, electrocatalytic, or bioelectronic devices. In this work the first tin-rich mesoporous indium tin oxide is prepared using the molecular heterobimetallic single-source precursor, indium tin tris-tert-butoxide, together with an appropriate structure-directing template, yielding materials with high surface areas and tailorable pore size. The resulting mesoporous tin-rich ITO films show a high and durable electrical conductivity and transparency, making them interesting materials for hosting electroactive biomolecules such as proteins. In fact, its unique performance in bioelectronic applications has been demonstrated by immobilization of high amounts of cytochrome c into the mesoporous film which undergo redox processes directly with the conductive electrode material.},
  language  = {en}
}
@article{YarmanNagelGajovicEichelmannetal.2011,
  author    = {Yarman, Aysu and Nagel, Thomas and Gajovic-Eichelmann, Nenad and Fischer, Anna and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Bioelectrocatalysis by Microperoxidase-11 in a Multilayer Architecture of Chitosan Embedded Gold Nanoparticles},
  series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis},
  volume    = {23},
  journal   = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis},
  number    = {3},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {1040-0397},
  doi       = {10.1002/elan.201000535},
  pages     = {611 -- 618},
  year      = {2011},
  abstract  = {We report on the redox behaviour of the microperoxidase-11 (MP-11) which has been electrostatically immobilized in a matrix of chitosan-embedded gold nanoparticles on the surface of a glassy carbon electrode. MP-11 contains a covalently bound heme c as the redox active group that exchanges electrons with the electrode via the gold nanoparticles. Electroactive surface concentration of MP-11 at high scan rate is between 350+/-50 pmol cm(-2), which reflects a multilayer process. The formal potential (E degrees') of MP-11 in the gold nanoparticles-chitosan film was estimated to be -(267.7+/-2.9) mV at pH 7.0. The heterogeneous electron transfer rate constant (k(s)) starts at 1.21 s(-1) and levels off at 6.45 s(-1) in the scan rate range from 0.1 to 2.0 V s(-1). Oxidation and reduction of MP-11 by hydrogen peroxide and superoxide, respectively have been coupled to the direct electron transfer of MP-11.},
  language  = {en}
}
@article{FrascaRojasSalewskietal.2012,
  author    = {Frasca, Stefano and Rojas, Oscar and Salewski, Johannes and Neumann, Bettina and Stiba, Konstanze and Weidinger, Inez M. and Tiersch, Brigitte and Leimk{\"u}hler, Silke and Koetz, Joachim and Wollenberger, Ursula},
  title     = {Human sulfite oxidase electrochemistry on gold nanoparticles modified electrode},
  series = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society},
  volume    = {87},
  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.2011.11.012},
  pages     = {33 -- 41},
  year      = {2012},
  abstract  = {The present study reports a facile approach for sulfite biosensing, based on enhanced direct electron transfer of a human sulfite oxidase (hSO) immobilized on a gold nanoparticles modified electrode. The spherical core shell AuNPs were prepared via a new method by reduction of HAuCl4 with branched poly(ethyleneimine) in an ionic liquids resulting particles with a diameter less than 10 nm. These nanoparticles were covalently attached to a mercaptoundecanoic acid modified Au-electrode where then hSO was adsorbed and an enhanced interfacial electron transfer and electrocatalysis was achieved. UV/Vis and resonance Raman spectroscopy, in combination with direct protein voltammetry, are employed for the characterization of the system and reveal no perturbation of the structural integrity of the redox protein. The proposed biosensor exhibited a quick steady-state current response, within 2 s, a linear detection range between 0.5 and 5.4 mu M with a high sensitivity (1.85 nA mu M-1). The investigated system provides remarkable advantages in the possibility to work at low applied potential and at very high ionic strength. Therefore these properties could make the proposed system useful in the development of bioelectronic devices and its application in real samples.},
  language  = {en}
}
@article{VerganiCarminatiFerrarietal.2012,
  author    = {Vergani, Marco and Carminati, Marco and Ferrari, Giorgio and Landini, Ettore and Caviglia, Claudia and Heiskanen, Arto and Comminges, Clement and Zor, Kinga and Sabourin, David and Dufva, Martin and Dimaki, Maria and Raiteri, Roberto and Wollenberger, Ursula and Emneus, Jenny and Sampietro, Marco},
  title     = {Multichannel bipotentiostat integrated with a microfluidic platform for electrochemical real-time monitoring of cell cultures},
  series = {IEEE Transactions on biomedical circuits and systems},
  volume    = {6},
  journal   = {IEEE Transactions on biomedical circuits and systems},
  number    = {5},
  publisher = {Inst. of Electr. and Electronics Engineers},
  address   = {Piscataway},
  issn      = {1932-4545},
  doi       = {10.1109/TBCAS.2012.2187783},
  pages     = {498 -- 507},
  year      = {2012},
  abstract  = {An electrochemical detection system specifically designed for multi-parameter real-time monitoring of stem cell culturing/differentiation in a microfluidic system is presented. It is composed of a very compact 24-channel electronic board, compatible with arrays of microelectrodes and coupled to a microfluidic cell culture system. A versatile data acquisition software enables performing amperometry, cyclic voltammetry and impedance spectroscopy in each of the 12 independent chambers over a 100 kHz bandwidth with current resolution down to 5 pA for 100 ms measuring time. The design of the platform, its realization and experimental characterization are reported, with emphasis on the analysis of impact of input capacitance (i.e., microelectrode size) and microfluidic pump operation on current noise. Programmable sequences of successive injections of analytes (ferricyanide and dopamine) and rinsing buffer solution as well as the impedimetric continuous tracking for seven days of the proliferation of a colony of PC12 cells are successfully demonstrated.},
  language  = {en}
}
@article{ColasEwenHannemannetal.2012,
  author    = {Colas, Helene and Ewen, Kerstin M. and Hannemann, Frank and Bistolas, Nikitas and Wollenberger, Ursula and Bernhardt, Rita and de Oliveira, Pedro},
  title     = {Direct and mediated electrochemical response of the cytochrome P450 106A2 from Bacillus megaterium ATCC 13368},
  series = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society},
  volume    = {87},
  journal   = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society},
  number    = {5},
  publisher = {Elsevier},
  address   = {Lausanne},
  issn      = {1567-5394},
  doi       = {10.1016/j.bioelechem.2012.01.006},
  pages     = {71 -- 77},
  year      = {2012},
  abstract  = {CYP106A2 is one of only a few known steroid hydroxylases of bacterial origin, which might be interesting for biotechnological applications. Despite the enzyme having been studied for more than 30 years, its physiological function remains elusive. To date, there have been no reports of the redox potential of CYP106A2, which was supposed to be unusually low for a cytochrome P450. In this work we show that cyclic voltammetry is not only suitable to determine the redox potential of challenging proteins such as CYP106A2, measured at - 128 mV vs. NHE, but also to study molecular interactions of the enzyme with different interaction partners via the respective electrochemical responses. The effect of small ligands, such as carbon monoxide and cyanide, was observed on the cyclic voltammograms of CYP106A2. Furthermore, we found that Tween 80 caused a positive shift of the redox potential of immobilised CYP106A2 indicative for water expulsion from the haem environment. Moreover, electron transfer mediation phenomena with biological redox partners (e.g. ferredoxins) were studied. Finally, the influence of two different kinds of substrates on the electrochemical response of CYP106A2 was assessed, aligning observations from spectral and electrochemical studies.},
  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{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{YarmanWollenbergerScheller2013,
  author    = {Yarman, Aysu and Wollenberger, Ursula and Scheller, Frieder W.},
  title     = {Sensors based on cytochrome P450 and CYP mimicking systems},
  series = {ELECTROCHIMICA ACTA},
  volume    = {110},
  journal   = {ELECTROCHIMICA ACTA},
  publisher = {PERGAMON-ELSEVIER SCIENCE LTD},
  address   = {OXFORD},
  issn      = {0013-4686},
  doi       = {10.1016/j.electacta.2013.03.154},
  pages     = {63 -- 72},
  year      = {2013},
  abstract  = {Cytochrome P450 enzymes (CYPs) act on more than 90 percent of all drugs currently on the market. The catalytic cycle requires electron supply to the heme iron in the presence of oxygen. Electrochemistry allows to characterise the reaction mechanism of these redox enzymes by observing the electron transfer in real time. According to the number of publications on protein electrochemistry CYP has the third position after glucose oxidase and cytochrome c. CYP based enzyme electrodes for the quantification of drugs, metabolites or pesticides have been developed using different iso-enzymes. A crucial step in the sensor development is the efficiency of coupling the biocatalytic systems with the electrode is. In the 1970s the direct electron transfer of heme and heme peptides called microperoxidases (MPs) was used as model of oxidoreductases. They exhibit a broad substrate spectrum including hydroxylation of selected aromatic substrates, demethylation and epoxidation by means of hydrogen peroxide. It overlaps with that of P450 making heme and MPs to alternate recognition elements in biosensors for the detection of typical CYP substrates. In these enzyme electrodes the signal is generated by the conversion of all substrates thus representing in complex media an overall parameter. By combining the biocatalytic substrate conversion with selective binding to a molecularly imprinted polymer layer the specificity has been improved. Here we discuss different approaches of biosensors based on CYP, microperoxidases and catalytically active MIPs and discuss their potential as recognition elements in biosensors. The performance of these sensors and their further development are discussed. (C) 2013 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{FrascaMilanGuietetal.2013,
  author    = {Frasca, Stefano and Milan, Anabel Molero and Guiet, Amandine and Goebel, Caren and Perez-Caballero, Fernando and Stiba, Konstanze and Leimk{\"u}hler, Silke and Fischer, Anna and Wollenberger, Ursula},
  title     = {Bioelectrocatalysis at mesoporous antimony doped tin oxide electrodes-Electrochemical characterization and direct enzyme communication},
  series = {ELECTROCHIMICA ACTA},
  volume    = {110},
  journal   = {ELECTROCHIMICA ACTA},
  number    = {2},
  publisher = {PERGAMON-ELSEVIER SCIENCE LTD},
  address   = {OXFORD},
  issn      = {0013-4686},
  doi       = {10.1016/j.electacta.2013.03.144},
  pages     = {172 -- 180},
  year      = {2013},
  abstract  = {In this paper we report immobilization and bioelectrocatalysis of human sulfite oxidase (hSO) on nanostructured antimony doped tin oxide (ATO) thin film electrodes. Two types of ATO thin film electrodes were prepared via evaporation induced self-assembly of ATO nanoparticle sols. The use of a porogen results in different porosity and film thickness. Nevertheless both electrode types reveal similar quasi reversible electrochemical behavior for positive and negatively charged small mediators. Facile and durable immobilization of catalytically active enzyme in a direct electron transfer configuration was achieved without further chemical modification of the ATO surfaces. Interestingly, the binding of hSO onto the ATO surface seems to be not only of electrostatic nature, but also originates from a strong interaction between the histidine-tag of the enzyme and the supporting material. This is suggested from stable sulfite dependent bioelectrocatalytic signals at high ionic strength and imidazole desorption experiments. As such, ATO appears as a promising conductive platform for the immobilization of complex enzymes and their application in bioelectrocatalysis. (C) 2013 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{XuWollenbergerQianetal.2013,
  author    = {Xu, Xuan and Wollenberger, Ursula and Qian, Jing and Lettau, Katrin and Jung, Christiane and Liu, Songqin},
  title     = {Electrochemically driven biocatalysis of the oxygenase domain of neuronal nitric oxide synthase in indium tin oxide nanoparticles/polyvinyl alcohol nanocomposite},
  series = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society},
  volume    = {94},
  journal   = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society},
  number    = {47},
  publisher = {Elsevier},
  address   = {Lausanne},
  issn      = {1567-5394},
  doi       = {10.1016/j.bioelechem.2013.04.005},
  pages     = {7 -- 12},
  year      = {2013},
  abstract  = {Nitric oxide synthase (NOS) plays a critical role in a number of key physiological and pathological processes. Investigation of electron-transfer reactions in NOS would contribute to a better understanding of the nitric oxide (NO) synthesis mechanism. Herein, we describe an electrochemically driven catalytic strategy, using a nanocomposite that consisted of the oxygenase domain of neuronal NOS (D290nNOSoxy), indium tin oxide (ITO) nanopartides and polyvinyl alcohol (PVA). Fast direct electron transfer between electrodes and D290nNOSoxy was observed with the heterogeneous electron transfer rate constant (k(er)) of 154.8 +/- 0.1 s(-1) at the scan rate of 5 V s(-1). Moreover, the substrate IV-hydroxy-L-arginine (NHA) was used to prove the concept of electrochemically driven biocatalysis of D290nNOSoxy. In the presence of the oxygen cosubstrate and tetrahydrobiopterin (BH4) cofactor, the addition of NHA caused the decreases of both oxidation current at + 0.1 V and reduction current at potentials ranging from -0.149 V to -0.549 V vs Ag/AgCl. Thereafter, a series of control experiments such as in the absence of BH4 or D290nNOSoxy were performed. All the results demonstrated that D290nNOSoxy biocatalysis was successfully driven by electrodes in the presence of BH4 and oxygen. This novel bioelectronic system showed potential for further investigation of NOS and biosensor applications. (C) 2013 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{BadalyanYogaSchwuchowetal.2013,
  author    = {Badalyan, Artavazd and Yoga, Etienne Galemou and Schwuchow, Viola and P{\"o}ller, Sascha and Schuhmann, Wolfgang and Leimk{\"u}hler, Silke and Wollenberger, Ursula},
  title     = {Analysis of the interaction of the molybdenum hydroxylase PaoABC from Escherichia coli with positively and negatively charged metal complexes},
  series = {Electrochemistry communications : an international journal dedicated to rapid publications in electrochemistry},
  volume    = {37},
  journal   = {Electrochemistry communications : an international journal dedicated to rapid publications in electrochemistry},
  publisher = {Elsevier},
  address   = {New York},
  issn      = {1388-2481},
  doi       = {10.1016/j.elecom.2013.09.017},
  pages     = {5 -- 7},
  year      = {2013},
  abstract  = {An unusual behavior of the periplasmic aldehyde oxidoreductase (PaoABC) from Escherichia coil has been observed from electrochemical investigations of the enzyme catalyzed oxidation of aromatic aldehydes with different mediators under different conditions of ionic strength. The enzyme has similarity to other molybdoenzymes of the xanthine oxidase family, but the catalytic behavior turned out to be very different. Under steady state conditions the turnover of PaoABC is maximal at pH 4 for the negatively charged ferricyanide and at pH 9 for a positively charged osmium complex. Stopped-flow kinetic measurements of the catalytic half reaction showed that oxidation of benzaldehyde proceeds also above pH 7. Thus, benzaldehyde oxidation can proceed under acidic and basic conditions using this enzyme, a property which has not been described before for molybdenum hydroxylases. It is also suggested that the electron transfer with artificial electron acceptors and PaoABC can proceed at different protein sites and depends on the nature of the electron acceptor in addition to the ionic strength. (C) 2013 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{BadalyanNeumannSchaalLeimkuehleretal.2013,
  author    = {Badalyan, Artavazd and Neumann-Schaal, Meina and Leimk{\"u}hler, Silke and Wollenberger, Ursula},
  title     = {A Biosensor for aromatic aldehydes comprising the mediator dependent PaoABC-Aldehyde oxidoreductase},
  series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis},
  volume    = {25},
  journal   = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis},
  number    = {1},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1040-0397},
  doi       = {10.1002/elan.201200362},
  pages     = {101 -- 108},
  year      = {2013},
  abstract  = {A novel aldehyde oxidoreductase (PaoABC) from Escherichia coli was utilized for the development of an oxygen insensitive biosensor for benzaldehyde. The enzyme was immobilized in polyvinyl alcohol and currents were measured for aldehyde oxidation with different one and two electron mediators with the highest sensitivity for benzaldehyde in the presence of hexacyanoferrate(III). The benzaldehyde biosensor was optimized with respect to mediator concentration, enzyme loading and pH using potassium hexacyanoferrate(III). The linear measuring range is between 0.5200 mu M benzaldehyde. In correspondence with the substrate selectivity of the enzyme in solution the biosensor revealed a preference for aromatic aldehydes and less effective conversion of aliphatic aldehydes. The biosensor is oxygen independent, which is a particularly attractive feature for application. The biosensor can be applied to detect contaminations with benzaldehyde in solvents such as benzyl alcohol, where traces of benzaldehyde in benzyl alcohol down to 0.0042?\% can be detected.},
  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{ZorHeiskanenCavigliaetal.2014,
  author    = {Zor, K. and Heiskanen, A. and Caviglia, Claudia and Vergani, M. and Landini, E. and Shah, F. and Carminati, Marco and Martinez-Serrano, A. and Ramos Moreno, T. and Kokaia, M. and Benayahu, Dafna and Keresztes, Zs. and Papkovsky, D. and Wollenberger, Ursula and Svendsen, W. E. and Dimaki, M. and Ferrari, G. and Raiteri, R. and Sampietro, M. and Dufva, M. and Emneus, Jenny},
  title     = {A compact multifunctional microfluidic platform for exploring cellular dynamics in real-time using electrochemical detection},
  series = {RSC Advances},
  volume    = {4},
  journal   = {RSC Advances},
  number    = {109},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2046-2069},
  doi       = {10.1039/c4ra12632g},
  pages     = {63761 -- 63771},
  year      = {2014},
  abstract  = {Downscaling of microfluidic cell culture and detection devices for electrochemical monitoring has mostly focused on miniaturization of the microfluidic chips which are often designed for specific applications and therefore lack functional flexibility. We present a compact microfluidic cell culture and electrochemical analysis platform with in-built fluid handling and detection, enabling complete cell based assays comprising on-line electrode cleaning, sterilization, surface functionalization, cell seeding, cultivation and electrochemical real-time monitoring of cellular dynamics. To demonstrate the versatility and multifunctionality of the platform, we explored amperometric monitoring of intracellular redox activity in yeast (Saccharomyces cerevisiae) and detection of exocytotically released dopamine from rat pheochromocytoma cells (PC12). Electrochemical impedance spectroscopy was used in both applications for monitoring cell sedimentation and adhesion as well as proliferation in the case of PC12 cells. The influence of flow rate on the signal amplitude in the detection of redox metabolism as well as the effect of mechanical stimulation on dopamine release were demonstrated using the programmable fluid handling capability. The here presented platform is aimed at applications utilizing cell based assays, ranging from e.g. monitoring of drug effects in pharmacological studies, characterization of neural stem cell differentiation, and screening of genetically modified microorganisms to environmental monitoring.},
  language  = {en}
}
@article{CommingesFrascaSuetterlinetal.2014,
  author    = {Comminges, Clement and Frasca, Stefano and Suetterlin, Martin and Wischerhoff, Erik and Laschewsky, Andr{\´e} and Wollenberger, Ursula},
  title     = {Surface modification with thermoresponsive polymer brushes for a switchable electrochemical sensor},
  series = {RSC Advances},
  volume    = {4},
  journal   = {RSC Advances},
  number    = {81},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2046-2069},
  doi       = {10.1039/c4ra07190e},
  pages     = {43092 -- 43097},
  year      = {2014},
  abstract  = {Elaboration of switchable surfaces represents an interesting way for the development of a new generation of electrochemical sensors. In this paper, a method for growing thermoresponsive polymer brushes from a gold surface pre-modified with polyethyleneimine (PEI), subsequent layer-by-layer polyelectrolyte assembly and adsorption of a charged macroinitiator is described. We propose an easy method for monitoring the coil-to-globule phase transition of the polymer brush using an electrochemical quartz crystal microbalance with dissipation (E-QCM-D). The surface of these polymer modified electrodes shows reversible switching from the swollen to the collapsed state with temperature. As demonstrated from E-QCM-D measurements using an original signal processing method, the switch is operating in three reversible steps related to different interfacial viscosities. Moreover, it is shown that the one electron oxidation of ferrocene carboxylic acid is dramatically affected by the change from the swollen to the collapsed state of the polymer brush, showing a spectacular 86\% decrease of the charge transfer resistance between the two states.},
  language  = {en}
}
@article{DeyAdamovskiFriebeetal.2014,
  author    = {Dey, Pradip and Adamovski, Miriam and Friebe, Simon and Badalyan, Artavazd and Mutihac, Radu-Cristian and Paulus, Florian and Leimk{\"u}hler, Silke and Wollenberger, Ursula and Haag, Rainer},
  title     = {Dendritic polyglycerol-poly(ethylene glycol)-based polymer networks for biosensing application},
  series = {ACS applied materials \& interfaces},
  volume    = {6},
  journal   = {ACS applied materials \& interfaces},
  number    = {12},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1944-8244},
  doi       = {10.1021/am502018x},
  pages     = {8937 -- 8941},
  year      = {2014},
  abstract  = {This work describes the formation of a new dendritic polyglycerol-poly(ethylene glycol)-based 3D polymer network as a matrix for immobilization of the redox enzyme periplasmatic aldehyde oxidoreductase to create an electrochemical biosensor. The novel network is built directly on the gold surface, where it simultaneously stabilizes the enzyme for up to 4 days. The prepared biosensors can be used for amperometric detection of benzaldehyde in the range of 0.8-400 mu M.},
  language  = {en}
}