@article{PilasYaziciSelmeretal.2017, author = {Pilas, Johanna and Yazici, Yasemen and Selmer, Thorsten and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Optimization of an amperometric biosensor array for simultaneous measurement of ethanol, formate, d- and l-lactate}, series = {Electrochimica Acta}, volume = {251}, journal = {Electrochimica Acta}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0013-4686}, doi = {10.1016/j.electacta.2017.07.119}, pages = {256 -- 262}, year = {2017}, abstract = {The immobilization of NAD+-dependent dehydrogenases, in combination with a diaphorase, enables the facile development of multiparametric sensing devices. In this work, an amperometric biosensor array for simultaneous determination of ethanol, formate, d- and l-lactate is presented. Enzyme immobilization on platinum thin-film electrodes was realized by chemical cross-linking with glutaraldehyde. The optimization of the sensor performance was investigated with regard to enzyme loading, glutaraldehyde concentration, pH, cofactor concentration and temperature. Under optimal working conditions (potassium phosphate buffer with pH 7.5, 2.5 mmol L-1 NAD+, 2.0 mmol L-1 ferricyanide, 25 °C and 0.4\% glutaraldehyde) the linear working range and sensitivity of the four sensor elements was improved. Simultaneous and cross-talk free measurements of four different metabolic parameters were performed successfully. The reliable analytical performance of the biosensor array was demonstrated by application in a clarified sample of inoculum sludge. Thereby, a promising approach for on-site monitoring of fermentation processes is provided.}, language = {en} } @article{BreuerMangSchoeningetal.2017, author = {Breuer, Lars and Mang, Thomas and Sch{\"o}ning, Michael Josef and Thoelen, Ronald and Wagner, Torsten}, title = {Investigation of the spatial resolution of a laser-based stimulation process for light-addressable hydrogels with incorporated graphene oxide by means of IR thermography}, series = {Sensors and Actuators A: Physical}, volume = {268}, journal = {Sensors and Actuators A: Physical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0924-4247}, doi = {10.1016/j.sna.2017.11.031}, pages = {126 -- 132}, year = {2017}, language = {en} } @article{MuschallikMolinnusBongaertsetal.2017, author = {Muschallik, Lukas and Molinnus, Denise and Bongaerts, Johannes and Pohl, Martina and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Siegert, Petra and Selmer, Thorsten}, title = {(R,R)-Butane-2,3-diol Dehydrogenase from Bacillus clausii DSM 8716T: Cloning and Expression of the bdhA-Gene, and Initial Characterization of Enzyme}, series = {Journal of Biotechnology}, volume = {258}, journal = {Journal of Biotechnology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0168-1656}, doi = {10.1016/j.jbiotec.2017.07.020}, pages = {41 -- 50}, year = {2017}, abstract = {The gene encoding a putative (R,R)-butane-2,3-diol dehydrogenase (bdhA) from Bacillus clausii DSM 8716T was isolated, sequenced and expressed in Escherichia coli. The amino acid sequence of the encoded protein is only distantly related to previously studied enzymes (identity 33-43\%) and exhibited some uncharted peculiarities. An N-terminally StrepII-tagged enzyme variant was purified and initially characterized. The isolated enzyme catalyzed the (R)-specific oxidation of (R,R)- and meso-butane-2,3-diol to (R)- and (S)-acetoin with specific activities of 12 U/mg and 23 U/mg, respectively. Likewise, racemic acetoin was reduced with a specific activity of up to 115 U/mg yielding a mixture of (R,R)- and meso-butane-2,3-diol, while the enzyme reduced butane-2,3-dione (Vmax 74 U/mg) solely to (R,R)-butane-2,3-diol via (R)-acetoin. For these reactions only activity with the co-substrates NADH/NAD+ was observed. The enzyme accepted a selection of vicinal diketones, α-hydroxy ketones and vicinal diols as alternative substrates. Although the physiological function of the enzyme in B. clausii remains elusive, the data presented herein clearly demonstrates that the encoded enzyme is a genuine (R,R)-butane-2,3-diol dehydrogenase with potential for applications in biocatalysis and sensor development.}, language = {en} } @article{PoghossianWernerBuniatyanetal.2017, author = {Poghossian, Arshak and Werner, Frederik and Buniatyan, V. V. and Wagner, Torsten and Miamoto, K. and Yoshinobu, T. and Sch{\"o}ning, Michael Josef}, title = {Towards addressability of light-addressable potentiometric sensors: Shunting effect of non-illuminated region and cross-talk}, series = {Sensor and Actuators B: Chemical}, journal = {Sensor and Actuators B: Chemical}, number = {244}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2017.01.047}, pages = {1071 -- 1079}, year = {2017}, abstract = {The LAPS (light-addressable potentiometric sensor) platform is one of the most attractive approaches for chemical and biological sensing with many applications ranging from pH and ion/analyte concentration measurements up to cell metabolism detection and chemical imaging. However, although it is generally accepted that LAPS measurements are spatially resolved, the light-addressability feature of LAPS devices has not been discussed in detail so far. In this work, an extended electrical equivalent-circuit model of the LAPS has been presented, which takes into account possible cross-talk effects due to the capacitive coupling of the non-illuminated region. A shunting effect of the non-illuminated area on the measured photocurrent and addressability of LAPS devices has been studied. It has been shown, that the measured photocurrent will be determined not only by the local interfacial potential in the illuminated region but also by possible interfacial potential changes in the non-illuminated region, yielding cross-talk effects. These findings were supported by the experimental investigations of a penicillin-sensitive multi-spot LAPS and a metal-insulator-semiconductor LAPS as model systems.}, language = {en} } @article{MolinnusPoghossianKeusgenetal.2017, author = {Molinnus, Denise and Poghossian, Arshak and Keusgen, Michael and Katz, Evgeny and Sch{\"o}ning, Michael Josef}, title = {Coupling of Biomolecular Logic Gates with Electronic Transducers: From Single Enzyme Logic Gates to Sense/Act/Treat Chips}, series = {Electroanalysis}, volume = {29}, journal = {Electroanalysis}, number = {8}, publisher = {Wiley}, address = {Weinheim}, issn = {1521-4109}, doi = {10.1002/elan.201700208}, pages = {1840 -- 1849}, year = {2017}, abstract = {The integration of biomolecular logic principles with electronic transducers allows designing novel digital biosensors with direct electrical output, logically triggered drug-release, and closed-loop sense/act/treat systems. This opens new opportunities for advanced personalized medicine in the context of theranostics. In the present work, we will discuss selected examples of recent developments in the field of interfacing enzyme logic gates with electrodes and semiconductor field-effect devices. Special attention is given to an enzyme OR/Reset logic gate based on a capacitive field-effect electrolyte-insulator-semiconductor sensor modified with a multi-enzyme membrane. Further examples are a digital adrenaline biosensor based on an AND logic gate with binary YES/NO output and an integrated closed-loop sense/act/treat system comprising an amperometric glucose sensor, a hydrogel actuator, and an insulin (drug) sensor.}, language = {en} } @inproceedings{JablonskiKochBronderetal.2017, author = {Jablonski, Melanie and Koch, Claudia and Bronder, Thomas and Poghossian, Arshak and Wege, Christina and Sch{\"o}ning, Michael Josef}, title = {Field-Effect Biosensors Modified with Tobacco Mosaic Virus Nanotubes as Enzyme Nanocarrier}, series = {MDPI Proceeding}, volume = {1}, booktitle = {MDPI Proceeding}, number = {4}, doi = {10.3390/proceedings1040505}, pages = {4}, year = {2017}, language = {en} } @article{KatzPoghossianSchoening2017, author = {Katz, Evgeny and Poghossian, Arshak and Sch{\"o}ning, Michael Josef}, title = {Enzyme-based logic gates and circuits - analytical applications and interfacing with electronics}, series = {Analytical and Bioanalytical Chemistry}, volume = {409}, journal = {Analytical and Bioanalytical Chemistry}, publisher = {Springer}, address = {Berlin}, issn = {1618-2650}, doi = {10.1007/s00216-016-0079-7}, pages = {81 -- 94}, year = {2017}, abstract = {The paper is an overview of enzyme-based logic gates and their short circuits, with specific examples of Boolean AND and OR gates, and concatenated logic gates composed of multi-step enzyme-biocatalyzed reactions. Noise formation in the biocatalytic reactions and its decrease by adding a "filter" system, converting convex to sigmoid response function, are discussed. Despite the fact that the enzyme-based logic gates are primarily considered as components of future biomolecular computing systems, their biosensing applications are promising for immediate practical use. Analytical use of the enzyme logic systems in biomedical and forensic applications is discussed and exemplified with the logic analysis of biomarkers of various injuries, e.g., liver injury, and with analysis of biomarkers characteristic of different ethnicity found in blood samples on a crime scene. Interfacing of enzyme logic systems with modified electrodes and semiconductor devices is discussed, giving particular attention to the interfaces functionalized with signal-responsive materials. Future perspectives in the design of the biomolecular logic systems and their applications are discussed in the conclusion.}, language = {en} } @article{BaeckerKochEibenetal.2017, author = {B{\"a}cker, Matthias and Koch, Claudia and Eiben, Sabine and Geiger, Fania and Eber, Fabian and Gliemann, Hartmut and Poghossian, Arshak and Wege, Christina and Sch{\"o}ning, Michael Josef}, title = {Tobacco mosaic virus as enzyme nanocarrier for electrochemical biosensors}, series = {Sensors and Actuators B: Chemical}, volume = {238}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2016.07.096}, pages = {716 -- 722}, year = {2017}, abstract = {The conjunction of (bio-)chemical recognition elements with nanoscale biological building blocks such as virus particles is considered as a very promising strategy for the creation of biohybrids opening novel opportunities for label-free biosensing. This work presents a new approach for the development of biosensors using tobacco mosaic virus (TMV) nanotubes or coat proteins (CPs) as enzyme nanocarriers. Sensor chips combining an array of Pt electrodes loaded with glucose oxidase (GOD)-modified TMV nanotubes or CP aggregates were used for amperometric detection of glucose as a model system for the first time. The presence of TMV nanotubes or CPs on the sensor surface allows binding of a high amount of precisely positioned enzymes without substantial loss of their activity, and may also ensure accessibility of their active centers for analyte molecules. Specific and efficient immobilization of streptavidin-conjugated GOD ([SA]-GOD) complexes on biotinylated TMV nanotubes or CPs was achieved via bioaffinity binding. These layouts were tested in parallel with glucose sensors with adsorptively immobilized [SA]-GOD, as well as [SA]-GOD crosslinked with glutardialdehyde, and came out to exhibit superior sensor performance. The achieved results underline a great potential of an integration of virus/biomolecule hybrids with electronic transducers for future applications in biosensorics and biochips.}, language = {en} } @inproceedings{MolinnusHardtKaeveretal.2017, author = {Molinnus, Denise and Hardt, Gabriel and K{\"a}ver, Larissa and Willenberg, Holger S. and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Detection of Adrenaline Based on Bioelectrocatalytical System to Support Tumor Diagnostic Technology}, series = {MDPI Proceedings}, booktitle = {MDPI Proceedings}, doi = {10.3390/proceedings1040506}, pages = {4 Seiten}, year = {2017}, language = {en} } @article{HonarvarfardGamellaChannaveerappaetal.2017, author = {Honarvarfard, Elham and Gamella, Maria and Channaveerappa, Devika and Darie, Costel C. and Poghossian, Arshak and Sch{\"o}ning, Michael Josef and Katz, Evgeny}, title = {Electrochemically Stimulated Insulin Release from a Modified Graphene-functionalized Carbon Fiber Electrode}, series = {Electroanalysis}, volume = {29}, journal = {Electroanalysis}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-4109}, doi = {10.1002/elan.201700095}, pages = {1543 -- 1553}, year = {2017}, abstract = {A graphene-functionalized carbon fiber electrode was modified with adsorbed polyethylenimine to introduce amino functionalities and then with trigonelline and 4-carboxyphenylboronic acid covalently bound to the amino groups. The trigonelline species containing quarterized pyridine groups produced positive charge on the electrode surface regardless of the pH value, while the phenylboronic acid species were neutral below pH 8 and negatively charged above pH 9 (note that their pKa=8.4). The total charge on the monolayer-modified electrode was positive at the neutral pH and negative at pH > 9. Note that 4-carboxyphenylboronic acid was attached to the electrode surface in molar excess to trigonelline, thus allowing the negative charge to dominate on the electrode surface at basic pH. Negatively charged fluorescent dye-labeled insulin (insulin-FITC) was loaded on the modified electrode surface at pH 7.0 due to its electrostatic attraction to the positively charged interface. The local pH in close vicinity to the electrode surface was increased to ca. 9-10 due to consumption of H+ ions upon electrochemical reduction of oxygen proceeding at the potential of -1.0 V (vs. Ag/AgCl) applied on the modified electrode. The process resulted in recharging of the electrode surface to the negative value due to the formation of the negative charge on the phenylboronic acid groups, thus resulting in the electrostatic repulsion of insulin-FITC and stimulating its release from the electrode surface. The insulin release was characterized by fluorescence spectroscopy (using the FITC-labeled insulin), by electrochemical measurements on an iridium oxide, IrOx, electrode and by mass spectrometry. The graphene-functionalized carbon fiber electrode demonstrated significant advantages in the signal-stimulated insulin release comparing with the carbon fiber electrode without the graphene species.}, language = {en} }