@article{HassanWollenberger2016, author = {Hassan, Rabeay Y. A. and Wollenberger, Ursula}, title = {Mediated bioelectrochemical system for biosensing the cell viability of Staphylococcus aureus}, series = {Analytical and bioanalytical chemistry : a merger of Fresenius' journal of analytical chemistry and Analusis}, volume = {408}, journal = {Analytical and bioanalytical chemistry : a merger of Fresenius' journal of analytical chemistry and Analusis}, publisher = {Springer}, address = {Heidelberg}, issn = {1618-2642}, doi = {10.1007/s00216-015-9134-z}, pages = {579 -- 587}, year = {2016}, abstract = {Staphylococcus aureus is one of the most dangerous human pathogens and is the cause of numerous illnesses ranging from moderate skin infections to life-threatening diseases. Despite advances made in identifying microorganisms, rapid detection methods for the viability of bacteria are still missing. Here, we report a rapid electrochemical assay for cell viability combining the use of double redox mediators and multiwall carbon nanotubes-screen printed electrodes (MWCNTs-SPE), ferricyanide (FCN) and 2,6-dichlorophenolindophenol (DCIP), which served as electron shuttle to enable the bacterial-electrode communications. The current originating from the metabolically active cells was recorded for probing the activity of the intracellular redox centers. Blocking of the respiratory chain pathways with electron transfer inhibitors demonstrated the involvement of the electron transport chain in the reaction. A good correlation between the number of the metabolically active cells and the current was obtained. The proposed assay has been exploited for monitoring cell proliferation of S. aureus during the growth. The sensitivity of the detection method reached 0.1 OD600. Therefore, the technique described is promising for estimating the cell number, measuring the cell viability, and probing intracellular redox center(s).}, 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{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{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{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{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{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{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{DongmoLeykDoscheetal.2016, author = {Dongmo, Saustin and Leyk, Janina and Dosche, Carsten and Richter-Landsberg, Christiane and Wollenberger, Ursula and Wittstock, Gunther}, title = {Electrogeneration of O-2(center dot-) and H2O2 Using Polymer-modified Microelectrodes in the Environment of Living Cells}, 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.201600267}, pages = {2400 -- 2407}, year = {2016}, abstract = {Microelectrodes modified with electropolymerized plumbagin (PLG) were used for the generation of superoxide radical (O-2(center dot-)) and hydrogen peroxide (H2O2) during oxygen reduction reaction (ORR) in an aqueous medium, specifically in serum-free cell culture media. This is enabled by the specific design of a polymer film on the microelectrode. The generation and diffusion of O-2(center dot-) during electrocatalytic ORR at a positionable PLG polymer-modified microelectrode was followed by fluorescence microscopy with the selective dye 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) and by amperometric detection using a cytochrome c-modified electrode at + 0.13 V. H2O2 production, either by direct oxygen reduction or as product of O-2(center dot-) disproportionation, was monitored by the reaction with Amplex UltraRed. The PLG polymer-modified microelectrodes were used to expose mammalian B6-RPE07 retinal cells to defined local fluxes of reactive oxygen species (ROS), and cellular responses and morphological alterations were observed. The use of a controllable source of ROS opens many possibilities to study how living cells respond to the presence of a certain flux of specific ROS.}, 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} } @article{CzolkosDockTonningetal.2016, author = {Czolkos, Ilja and Dock, Eva and Tonning, Erik and Christensen, Jakob and Winther-Nielsen, Margrethe and Carlsson, Charlotte and Mojzikova, Renata and Skladal, Petr and Wollenberger, Ursula and Norgaard, Lars and Ruzgas, Tautgirdas and Emneus, Jenny}, title = {Prediction of wastewater quality using amperometric bioelectronic tongues}, series = {Marine policy}, volume = {75}, journal = {Marine policy}, publisher = {Elsevier}, address = {Oxford}, issn = {0956-5663}, doi = {10.1016/j.bios.2015.08.055}, pages = {375 -- 382}, year = {2016}, abstract = {Wastewater samples from a Swedish chemi-thermo-mechanical pulp (CTMP) mill collected at different purification stages in a wastewater treatment plant (WWTP) were analyzed with an amperometric enzyme-based biosensor array in a flow-injection system. In order to resolve the complex composition of the wastewater, the array consists of several sensing elements which yield a multidimensional response. We used principal component analysis (PCA) to decompose the array's responses, and found that wastewater with different degrees of pollution can be differentiated. With the help of partial least squares regression (PLS-R), we could link the sensor responses to the toxicity parameter, as well as to global organic pollution parameters (COD, BOD, and TOC). From investigating the influences of individual sensors in the array, it was found that the best models were in most cases obtained when all sensors in the array were included in the PLS-R model. We find that fast simultaneous determination of several global environmental parameters characterizing wastewaters is possible with this kind of biosensor array, in particular because of the link between the sensor responses and the biological effect onto the ecosystem into which the wastewater would be released. In conjunction with multivariate data analysis tools, there is strong potential to reduce the total time until a result is yielded from days to a few minutes.}, language = {en} } @article{ContinFrascaVivekananthanetal.2015, author = {Contin, Andrea and Frasca, Stefano and Vivekananthan, Jeevanthi and Leimk{\"u}hler, Silke and Wollenberger, Ursula and Plumere, Nicolas and Schuhmann, Wolfgang}, title = {A pH Responsive Redox Hydrogel for Electrochemical Detection of Redox Silent Biocatalytic Processes. Control of Hydrogel Solvation}, series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, volume = {27}, journal = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, number = {4}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1040-0397}, doi = {10.1002/elan.201400621}, pages = {938 -- 944}, year = {2015}, abstract = {The control of bioelectrocatalytic processes by external stimuli for the indirect detection of non-redox active species was achieved using an esterase and a redox enzyme both integrated within a redox hydrogel. The poly( vinyl) imidazole Os(bpy)(2)Cl hydrogel displays pH-responsive properties. The esterase catalysed reaction leads to a local pH decrease causing protonation of imidazole moieties thus increasing hydrogel solvation and mobility of the tethered Os-complexes. This is the key step to enable improved electron transfer between an aldehyde oxidoreductase and the polymer-bound Os-complexes. The off-on switch is further integrated in a biofuel cell system for self-powered signal generation.}, 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{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{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{CazellesLalaouiHartmannetal.2016, author = {Cazelles, R. and Lalaoui, N. and Hartmann, Tobias and Leimk{\"u}hler, Silke and Wollenberger, Ursula and Antonietti, Markus and Cosnier, S.}, title = {Ready to use bioinformatics analysis as a tool to predict immobilisation strategies for protein direct electron transfer (DET)}, series = {Polymer : the international journal for the science and technology of polymers}, volume = {85}, journal = {Polymer : the international journal for the science and technology of polymers}, publisher = {Elsevier}, address = {Oxford}, issn = {0956-5663}, doi = {10.1016/j.bios.2016.04.078}, pages = {90 -- 95}, year = {2016}, 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{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{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{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} }