TY - JOUR A1 - Schusser, Sebastian A1 - Krischer, Maximillian A1 - Bäcker, Matthias A1 - Poghossian, Arshak A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Monitoring of the Enzymatically Catalyzed Degradation of Biodegradable Polymers by Means of Capacitive Field-Effect Sensors JF - Analytical Chemistry N2 - Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte–insulator–semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(d,l-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers. Y1 - 2015 U6 - http://dx.doi.org/10.1021/acs.analchem.5b00617 SN - 1520-6882 VL - 87 IS - 13 SP - 6607 EP - 6613 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Schusser, Sebastian A1 - Krischer, M. A1 - Molin, D. G. M. A1 - Akker, N. M. S. van den A1 - Bäcker, Matthias A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Sensor System for in-situ and Real-time Monitoring of Polymer (bio) degradation JF - Procedia Engineering N2 - A sensor system for investigating (bio)degradationprocesses of polymers is presented. The system utilizes semiconductor field-effect sensors and is capable of monitoring the degradation process in-situ and in real-time. The degradation of the polymer poly(d,l-lactic acid) is exemplarily monitored in solutions with different pH value, pH-buffer solution containing the model enzyme lipase from Rhizomucormiehei and cell-culture medium containing supernatants from stimulated and non-stimulated THP-1-derived macrophages mimicking activation of the immune system. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.proeng.2015.08.815 SN - 1877-7058 N1 - Eurosensors 2015 VL - 120 SP - 948 EP - 951 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schubert, J. A1 - Schöning, Michael Josef A1 - Mourzina, Y. G. A1 - Legin, A. V. A1 - Vlasov, Y. G. A1 - Zander, W. A1 - Lüth, H. T1 - Multicomponent thin films for electrochemical sensor applications prepared by pulsed laser deposition JF - Sensors and Actuators B. 76 (2001), H. 1-3 Y1 - 2001 SN - 0925-4005 SP - 327 EP - 330 ER - TY - JOUR A1 - Schroth, P. A1 - Weißbecker, B. A1 - Schütz, S. A1 - Ecken, H. A1 - Yoshinobu, T. A1 - Lüth, H. A1 - Schöning, Michael Josef T1 - Bioelectronic signal processing - intact chemoreceptors coupled to field-effect devices JF - Lecture Notes of the ICB Seminars Y1 - 2002 SP - 28 EP - 42 PB - MCB CY - Warsaw ER - TY - JOUR A1 - Schroth, P. A1 - Weißbecker, B. A1 - Schütz, S. A1 - Ecken, H. A1 - Yoshinobu, T. A1 - Lüth, H. A1 - Schöning, Michael Josef T1 - Bioelectronic signal processing - intact chemoreceptors coupled to field-effect devices JF - Biocybernetics and Biomedical Engineering. 21 (2001), H. 3 Y1 - 2001 SN - 0208-5216 SP - 27 EP - 42 ER - TY - JOUR A1 - Schroth, P. A1 - Schöning, Michael Josef A1 - Lüth, H. A1 - Weißbecker, B. A1 - Hummel, Hans E. A1 - Schütz, S. T1 - Extending the capabilities of an antenna/chip biosensor by employing various insect species JF - Sensors and Actuators B. 78 (2001), H. 1-3 Y1 - 2001 SN - 0925-4005 SP - 1 EP - 5 ER - TY - JOUR A1 - Schroth, P. A1 - Schöning, Michael Josef A1 - Lüth, H. A1 - Weißbecker, B. A1 - Hummel, Hans E. A1 - Schütz, S. T1 - Extending the capabilities of an antenna/chip biosensor by employing various insect species JF - Proceedings : Copenhagen, Denmark, 27 - 30 August 2000 / [ed.: R. de Reus ...] Y1 - 2000 SN - 87-89935-50-0 N1 - Eurosensors ; (14, 2000, København) ; Eurosensors ; (14 : ; 2000.08.27-30 : ; Copenhagen) ; European Conference on Solid-State Transducers ; (14 : ; 2000.08.27-30 : ; Copenhagen) SP - 27 EP - 30 PB - MIC, Mikroelektronik Centret CY - Lyngby, Denmark ER - TY - JOUR A1 - Schroth, P. A1 - Lüth, H. A1 - Hummel, Hans E. A1 - Schütz, S. A1 - Schöning, Michael Josef T1 - Characterising an insect antenna as a receptor for a biosensor by means of impedance spectroscopy JF - Scaling down in electrochemistry : electrochemical micro- and nanosystem technology ; proceedings of the 3rd International Symposium on Electrochemical Microsystem Technologies, Garmisch-Patenkirchen, Germany, 11 - 15 September 2000 / ed. by J. W. Schultz Y1 - 2001 SN - 0-08-044014-2 SP - 293 EP - 297 PB - Elsevier [u.a.] CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Schroeter, Rebecca A1 - Hoffmann, Tamara A1 - Voigt, Birgit A1 - Meyer, Hanna A1 - Bleisteiner, Monika A1 - Muntel, Jan A1 - Jürgen, Britta A1 - Albrecht, Dirk A1 - Becher, Dörte A1 - Lalk, Michael A1 - Evers, Stefan A1 - Bongaerts, Johannes A1 - Maurer, Karl-Heinz A1 - Putzer, Harald A1 - Hecker, Michael A1 - Schweder, Thomas A1 - Bremer, Erhard T1 - Stress responses of the industrial workhorse Bacillus licheniformis to osmotic challenges JF - PLoS ONE N2 - The Gram-positive endospore-forming bacterium Bacillus licheniformis can be found widely in nature and it is exploited in industrial processes for the manufacturing of antibiotics, specialty chemicals, and enzymes. Both in its varied natural habitats and in industrial settings, B. licheniformis cells will be exposed to increases in the external osmolarity, conditions that trigger water efflux, impair turgor, cause the cessation of growth, and negatively affect the productivity of cell factories in biotechnological processes. We have taken here both systems-wide and targeted physiological approaches to unravel the core of the osmostress responses of B. licheniformis. Cells were suddenly subjected to an osmotic upshift of considerable magnitude (with 1 M NaCl), and their transcriptional profile was then recorded in a time-resolved fashion on a genome-wide scale. A bioinformatics cluster analysis was used to group the osmotically up-regulated genes into categories that are functionally associated with the synthesis and import of osmostress-relieving compounds (compatible solutes), the SigB-controlled general stress response, and genes whose functional annotation suggests that salt stress triggers secondary oxidative stress responses in B. licheniformis. The data set focusing on the transcriptional profile of B. licheniformis was enriched by proteomics aimed at identifying those proteins that were accumulated by the cells through increased biosynthesis in response to osmotic stress. Furthermore, these global approaches were augmented by a set of experiments that addressed the synthesis of the compatible solutes proline and glycine betaine and assessed the growth-enhancing effects of various osmoprotectants. Combined, our data provide a blueprint of the cellular adjustment processes of B. licheniformis to both sudden and sustained osmotic stress. Y1 - 2014 U6 - http://dx.doi.org/10.1371/journal.pone.0080956 SN - 1932-6203 VL - 8 IS - 11 PB - PLOS CY - San Francisco ER - TY - JOUR A1 - Scholl, Fabio A1 - Morais, Paulo A1 - Gabriel, Rayla A1 - Schöning, Michael Josef A1 - Siqueira, Jose Roberto, Jr. A1 - Caseli, Luciano T1 - Carbon nanotubes arranged as smart interfaces in lipid Langmuir-Blodgett films enhancing the enzymatic properties of penicillinase for biosensing applications JF - Applied Materials & Interfaces N2 - In this paper, carbon nanotubes (CNTs) were incorporated in penicillinase-phospholipid Langmuir and Langmuir–Blodgett (LB) films to enhance the enzyme catalytic properties. Adsorption of the penicillinase and CNTs at dimyristoylphosphatidic acid (DMPA) monolayers at the air–water interface was investigated by surface pressure–area isotherms, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to solid supports through the LB technique, forming mixed DMPA-CNTs-PEN films, which were investigated by quartz crystal microbalance, vibrational spectroscopy, and atomic force microscopy. Enzyme activity was studied with UV–vis spectroscopy and the feasibility of the supramolecular device nanostructured as ultrathin films were essayed in a capacitive electrolyte–insulator–semiconductor (EIS) sensor device. The presence of CNTs in the enzyme–lipid LB film not only tuned the catalytic activity of penicillinase but also helped conserve its enzyme activity after weeks, showing increased values of activity. Viability as penicillin sensor was demonstrated with capacitance/voltage and constant capacitance measurements, exhibiting regular and distinctive output signals over all concentrations used in this work. These results may be related not only to the nanostructured system provided by the film, but also to the synergism between the compounds on the active layer, leading to a surface morphology that allowed a fast analyte diffusion because of an adequate molecular accommodation, which also preserved the penicillinase activity. This work therefore demonstrates the feasibility of employing LB films composed of lipids, CNTs, and enzymes as EIS devices for biosensing applications. Y1 - 2017 U6 - http://dx.doi.org/10.1021/acsami.7b08095 SN - 1944-8252 VL - 9 IS - 36 SP - 31054 EP - 31066 PB - ACS CY - Washington ER - TY - JOUR A1 - Schmitt, G. A1 - Werner, C. A1 - Schöning, Michael Josef T1 - Microelectrochemical efficiency evaluation of inhibitors for CO2 corrosion of carbon steel under high shear stress gradients JF - Corrosion 2002. Conference Proceedings. NACExpo, 57th Annual Conference and Exhibition, Denver, US, Apr 7-11, 2002 Y1 - 2002 N1 - Paper 02280 SP - 1 EP - 11 PB - NACE International CY - Houston, Texas ER - TY - JOUR A1 - Schmitt, G. A1 - Faßbender, F. A1 - Lüth, H. A1 - Schöning, Michael Josef A1 - Schultze, J. W. A1 - Buß, G. T1 - Passivation and corrosion of microelectrode arrays JF - Materials and Corrosion. 51 (2000), H. 1 Y1 - 2000 SN - 0947-5117 SP - 20 EP - 25 ER - TY - JOUR A1 - Schmidt, R. A1 - Tonnesmann, A. A1 - Förster, Arnold A1 - Grimm, M. A1 - Kordos, P. A1 - Lüth, H. T1 - Metamorphic InAlAs/InGaAs HEMT's on GaAs substrates using an InP buffer layer JF - 8th IEEE International Symposium on High Performance Electron Devices for Microwave and Optoelectronic Applications : EDMO 2000 ; [13 - 14 November 2000, University of Glasgow] / organised by Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow Scotland. MTT/ED/AP/LEO Societies Joint Chapter, United Kingdom and Republic of Ireland Section. With technical co-sponsorship from IEEE Electron Device Society Y1 - 2000 SN - 0-7803-6550-X N1 - EDMO <8, 2000, Glasgow> ; University / Department of Electronics and Electrical Engineering ; IEEE catalog number 00TH8534 SP - 95 EP - 98 PB - IEEE Operations Center CY - Piscataway, NJ ER - TY - JOUR A1 - Schiffels, Johannes A1 - Selmer, Thorsten T1 - A flexible toolbox to study protein-assisted metalloenzyme assembly in vitro JF - Biotechnology and Bioengineering Y1 - 2015 U6 - http://dx.doi.org/10.1002/bit.25658 SN - 1097-0290 VL - 112 IS - 11 SP - 2360 EP - 2372 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Schiffels, Johannes A1 - Selmer, Thorsten T1 - Combinatorial assembly of ferredoxin‐linked modules in Escherichia coli yields a testing platform for Rnf‐complexes JF - Biotechnology and Bioengineering Y1 - 2019 U6 - http://dx.doi.org/10.1002/bit.27079 IS - accepted article SP - 1 EP - 36 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Schiffels, Johannes A1 - Pinkenburg, Olaf A1 - Schelden, Maximilian A1 - Aboulnaga, El-Hussiny A. A. A1 - Baumann, Marcus A1 - Selmer, Thorsten T1 - An innovative cloning platform enables large-scale production and maturation of an oxygen-tolerant [NiFe]-hydrogenase from cupriavidus necator in Escherichia coli JF - PLOS one. 2013 Y1 - 2013 U6 - http://dx.doi.org/10.1371/journal.pone.0068812 SN - 1932-6203 PB - Public Library of Science CY - San Francisco, California ER - TY - JOUR A1 - Scheele, Sandra A1 - Oertel, Dan A1 - Bongaerts, Johannes A1 - Evers, Stefan A1 - Hellmuth, Hendrik A1 - Maurer, Karl-Heinz A1 - Bott, Michael A1 - Freudl, Roland T1 - Secretory production of an FAD cofactor-containing cytosolic enzyme (sorbitol–xylitol oxidase from Streptomyces coelicolor) using the twin-arginine translocation (Tat) pathway of Corynebacterium glutamicum JF - Microbial biotechnology Y1 - 2013 SN - 1751-7915 SP - 202 EP - 206 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Sabitova, A. A1 - Ebert, Ph. A1 - Lenz, A. A1 - Schaafhausen, S. A1 - Ivanova, L. A1 - Dähne, M. A1 - Hoffmann, A. A1 - Dunin-Borkowski, R. E. A1 - Förster, Arnold A1 - Grandidier, B. A1 - Eisele, H. T1 - Intrinsic bandgap of cleaved ZnO(112¯0) surfaces JF - Applied physics letters Y1 - 2013 SN - 1077-3118 (E-Journal); 0003-6951 (Print) VL - Vol. 102 SP - 021608 ER - TY - JOUR A1 - Röhlen, Desiree A1 - Pilas, Johanna A1 - Schöning, Michael Josef A1 - Selmer, Thorsten T1 - Development of an amperometric biosensor platform for the combined determination of l-Malic, Fumaric, and l-Aspartic acid JF - Applied Biochemistry and Biotechnology N2 - Three amperometric biosensors have been developed for the detection of L-malic acid, fumaric acid, and L -aspartic acid, all based on the combination of a malate-specific dehydrogenase (MDH, EC 1.1.1.37) and diaphorase (DIA, EC 1.8.1.4). The stepwise expansion of the malate platform with the enzymes fumarate hydratase (FH, EC 4.2.1.2) and aspartate ammonia-lyase (ASPA, EC 4.3.1.1) resulted in multi-enzyme reaction cascades and, thus, augmentation of the substrate spectrum of the sensors. Electrochemical measurements were carried out in presence of the cofactor β-nicotinamide adenine dinucleotide (NAD+) and the redox mediator hexacyanoferrate (III) (HCFIII). The amperometric detection is mediated by oxidation of hexacyanoferrate (II) (HCFII) at an applied potential of + 0.3 V vs. Ag/AgCl. For each biosensor, optimum working conditions were defined by adjustment of cofactor concentrations, buffer pH, and immobilization procedure. Under these improved conditions, amperometric responses were linear up to 3.0 mM for L-malate and fumarate, respectively, with a corresponding sensitivity of 0.7 μA mM−1 (L-malate biosensor) and 0.4 μA mM−1 (fumarate biosensor). The L-aspartate detection system displayed a linear range of 1.0–10.0 mM with a sensitivity of 0.09 μA mM−1. The sensor characteristics suggest that the developed platform provides a promising method for the detection and differentiation of the three substrates. Y1 - 2017 U6 - http://dx.doi.org/10.1007/s12010-017-2578-1 SN - 1559-0291 VL - 183 SP - 566 EP - 581 PB - Springer CY - Berlin ER - TY - JOUR A1 - Röhlen, Desiree A1 - Pilas, Johanna A1 - Dahmen, Markus A1 - Keusgen, Michael A1 - Selmer, Thorsten A1 - Schöning, Michael Josef T1 - Toward a Hybrid Biosensor System for Analysis of Organic and Volatile Fatty Acids in Fermentation Processes JF - Frontiers in Chemistry N2 - Monitoring of organic acids (OA) and volatile fatty acids (VFA) is crucial for the control of anaerobic digestion. In case of unstable process conditions, an accumulation of these intermediates occurs. In the present work, two different enzyme-based biosensor arrays are combined and presented for facile electrochemical determination of several process-relevant analytes. Each biosensor utilizes a platinum sensor chip (14 × 14 mm²) with five individual working electrodes. The OA biosensor enables simultaneous measurement of ethanol, formate, d- and l-lactate, based on a bi-enzymatic detection principle. The second VFA biosensor provides an amperometric platform for quantification of acetate and propionate, mediated by oxidation of hydrogen peroxide. The cross-sensitivity of both biosensors toward potential interferents, typically present in fermentation samples, was investigated. The potential for practical application in complex media was successfully demonstrated in spiked sludge samples collected from three different biogas plants. Thereby, the results obtained by both of the biosensors were in good agreement to the applied reference measurements by photometry and gas chromatography, respectively. The proposed hybrid biosensor system was also used for long-term monitoring of a lab-scale biogas reactor (0.01 m³) for a period of 2 months. In combination with typically monitored parameters, such as gas quality, pH and FOS/TAC (volatile organic acids/total anorganic carbonate), the amperometric measurements of OA and VFA concentration could enhance the understanding of ongoing fermentation processes. Y1 - 2018 U6 - http://dx.doi.org/10.3389/fchem.2018.00284 IS - 6 PB - Frontiers CY - Lausanne ER - TY - JOUR A1 - Rosenauer, A. A1 - Oberst, W. A1 - Litvinov, D. A1 - Gerthsen, D. A1 - Förster, Arnold A1 - Schmidt, R. T1 - Structural and Chemical Investigation of In-0.6Ga0.4As Stranski-Krastanow Layers Burried in GaAs by Transmission Electron Microscopy JF - Physical Review B. 61 (2000), H. 12 Y1 - 2000 SN - 1095-3795 SP - 8276 EP - 8288 ER - TY - JOUR A1 - Rolka, David A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Integration of a capacitive EIS sensor into a FIA system for pH and penicillin determination JF - Sensors. 4 (2004) Y1 - 2004 SN - 1424-8220 SP - 84 EP - 94 ER - TY - JOUR A1 - Rodrigues, Raul T. A1 - Morais, Paulo V. A1 - Nordi, Cristina S. F. A1 - Schöning, Michael Josef A1 - Siqueira Jr., José R. A1 - Caseli, Luciano T1 - Carbon Nanotubes and Algal Polysaccharides To Enhance the Enzymatic Properties of Urease in Lipid Langmuir-Blodgett Films JF - Langmuir N2 - Algal polysaccharides (extracellular polysaccharides) and carbon nanotubes (CNTs) were adsorbed on dioctadecyldimethylammonium bromide Langmuir monolayers to serve as a matrix for the incorporation of urease. The physicochemical properties of the supramolecular system as a monolayer at the air–water interface were investigated by surface pressure–area isotherms, surface potential–area isotherms, interfacial shear rheology, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to hydrophilic solid supports, quartz, mica, or capacitive electrolyte–insulator–semiconductor (EIS) devices, through the Langmuir–Blodgett (LB) technique, forming mixed films, which were investigated by quartz crystal microbalance, fluorescence spectroscopy, and field emission gun scanning electron microscopy. The enzyme activity was studied with UV–vis spectroscopy, and the feasibility of the thin film as a urea sensor was essayed in an EIS sensor device. The presence of CNT in the enzyme–lipid LB film not only tuned the catalytic activity of urease but also helped to conserve its enzyme activity. Viability as a urease sensor was demonstrated with capacitance–voltage and constant capacitance measurements, exhibiting regular and distinctive output signals over all concentrations used in this work. These results are related to the synergism between the compounds on the active layer, leading to a surface morphology that allowed fast analyte diffusion owing to an adequate molecular accommodation, which also preserved the urease activity. This work demonstrates the feasibility of employing LB films composed of lipids, CNT, algal polysaccharides, and enzymes as EIS devices for biosensing applications. Y1 - 2018 U6 - http://dx.doi.org/10.1021/acs.langmuir.7b04317 SN - 1520-5827 VL - 34 IS - 9 SP - 3082 EP - 3093 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Riemer, A. A1 - Schroth, P. A1 - Schütz, S. A1 - Hummel, Hans E. A1 - Lüth, H. A1 - Kohl, C.-D. A1 - Schöning, Michael Josef T1 - The future of fire detection: Biological sensors? – Die Zukunft der Brandgassensorik: Biologische Sensoren? JF - Gassensorik in der Brandmeldetechnik : [VdS-Fachtagung, am 15. und 16. November 2000 in Köln] = Gas sensors for fire detection / VdS Schadenverhütung Y1 - 2000 N1 - Fachtagung Gassensorik in der Brandmeldetechnik ; (2000, Köln) SP - 1 EP - 7 PB - VdS Schadenverhütung CY - Köln ER - TY - JOUR A1 - Ribitsch, D. A1 - Karl, W. A1 - Birner-Gruenberger, R. A1 - Gruber, K. A1 - Eiteljoerg, I. A1 - Remler, P. A1 - Wieland, S. A1 - Siegert, Petra A1 - Maurer, Karl-Heinz A1 - Schwab, H. T1 - C-terminal truncation of a metagenome-derived detergent protease for effective expression in E. coli JF - Journal of biotechnology N2 - Recently, a new alkaline protease named HP70 showing highest homology to extracellular serine proteases of Stenotrophomonas maltophilia and Xanthomonas campestris was found in the course of a metagenome screening for detergent proteases (Niehaus et al., submitted for publication). Attempts to efficiently express the enzyme in common expression hosts had failed. This study reports on the realization of overexpression in Escherichia coli after structural modification of HP70. Modelling of HP70 resulted in a two-domain structure, comprising the catalytic domain and a C-terminal domain which includes about 100 amino acids. On the basis of the modelled structure the enzyme was truncated by deletion of most of the C-terminal domain yielding HP70-C477. This structural modification allowed effective expression of active enzyme using E. coli BL21-Gold as the host. Specific activity of HP70-C477 determined with suc-l-Ala-l-Ala-l-Pro-l-Phe-p-nitroanilide as the substrate was 30 ± 5 U/mg compared to 8 ± 1 U/mg of the native enzyme. HP70-C477 was most active at 40 °C and pH 7–11; these conditions are prerequisite for a potential application as detergent enzyme. Determination of kinetic parameters at 40 °C and pH = 9.5 resulted in KM = 0.23 ± 0.01 mM and kcat = 167.5 ± 3.6 s⁻¹. MS-analysis of peptide fragments obtained from incubation of HP70 and HP70-C477 with insulin B indicated that the C-terminal domain influences the cleavage preferences of the enzyme. Washing experiments confirmed the high potential of HP70-C477 as detergent protease. Y1 - 2010 U6 - http://dx.doi.org/10.1016/j.jbiotec.2010.09.947 SN - 1873-4863 (E-Journal); 0168-1656 (Print) VL - 150 IS - 3 SP - 408 EP - 416 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Ribitsch, D. A1 - Heumann, S. A1 - Karl, W. A1 - Gerlach, J. A1 - Leber, R. A1 - Birner-Gruenberger, R. A1 - Gruber, K. A1 - Eiteljoerg, I. A1 - Remler, P. A1 - Siegert, Petra A1 - Lange, J. A1 - Maurer, Karl-Heinz A1 - Berg, G. A1 - Guebitz, G. M. A1 - Schwab, H. T1 - Extracellular serine proteases from Stenotrophomonas maltophilia: Screening, isolation and heterologous expression in E. coli JF - Journal of biotechnology N2 - A large strain collection comprising antagonistic bacteria was screened for novel detergent proteases. Several strains displayed protease activity on agar plates containing skim milk but were inactive in liquid media. Encapsulation of cells in alginate beads induced protease production. Stenotrophomonas maltophilia emerged as best performer under washing conditions. For identification of wash-active proteases, four extracellular serine proteases called StmPr1, StmPr2, StmPr3 and StmPr4 were cloned. StmPr2 and StmPr4 were sufficiently overexpressed in E. coli. Expression of StmPr1 and StmPr3 resulted in unprocessed, insoluble protein. Truncation of most of the C-terminal domain which has been identified by enzyme modeling succeeded in expression of soluble, active StmPr1 but failed in case of StmPr3. From laundry application tests StmPr2 turned out to be a highly wash-active protease at 45 °C. Specific activity of StmPr2 determined with suc-l-Ala-l-Ala-l-Pro-l-Phe-p-nitroanilide as the substrate was 17 ± 2 U/mg. In addition we determined the kinetic parameters and cleavage preferences of protease StmPr2. KW - Alginate beads KW - Stenotrophomonas maltophilia KW - Detergent protease Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.jbiotec.2011.09.025 SN - 1873-4863 (E-Journal); 0168-1656 (Print) VL - 157 IS - 1 SP - 140 EP - 147 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Reisert, Steffen A1 - Schneider, Benno A1 - Geissler, Hanno A1 - Gompel, Matthias van A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Multi-sensor chip for the investigation of different types of metal oxides for the detection of H2O2 in the ppm range JF - physica status solidi (a) N2 - In this work, a multi-sensor chip for the investigation of the sensing properties of different types of metal oxides towards hydrogen peroxide in the ppm range is presented. The fabrication process and physical characterization of the multi-sensor chip are described. Pure SnO2 and WO3 as well as Pd- and Pt-doped SnO2 films are characterized in terms of their sensitivity to H2O2. The sensing films have been prepared by drop-coating of water-dispensed nano-powders. A physical characterization, including scanning electron microscopy and X-ray diffraction analysis of the deposited metal-oxide films, was done. From the measurements in hydrogen peroxide atmosphere, it could be shown, that all of the tested metal oxide films are suitable for the detection of H2O2 in the ppm range. The highest sensitivity and reproducibility was achieved using Pt-doped SnO2. Calibration plot of a SnO2, WO3, Pt-, and Pd-doped SnO2 gas sensor for H2O2 concentrations in the ppm range. Y1 - 2013 SN - 1862-6319 VL - 210 IS - 5 SP - 898 EP - 904 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Reisert, Steffen A1 - Henkel, Hartmut A1 - Schneider, Andreas A1 - Schäfer, Daniel A1 - Friedrich, Peter A1 - Berger, Jörg A1 - Schöning, Michael Josef T1 - Development of a handheld sensor system for the online measurement of hydrogen peroxide in aseptic filling systems JF - Physica Status Solidi (A). 207 (2010), H. 4 Y1 - 2010 SN - 1862-6300 N1 - Special Issue: Engineering of Functional Interfaces EnFI 2009 SP - 913 EP - 918 ER - TY - JOUR A1 - Reisert, Steffen A1 - Geissler, Hanno A1 - Flörke, Rudolf A1 - Weiler, Christian A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Characterisation of aseptic sterilisation processes using an electronic nose JF - International journal of nanotechnology Y1 - 2013 SN - 1475-7435 (Print) 7141-8151 (Online) VL - Vol. 10 IS - No. 5-7 SP - 470 EP - 484 PB - Inderscience Enterprises CY - Genève ER - TY - JOUR A1 - Reisert, Steffen A1 - Geissler, Hanno A1 - Flörke, Rudolf A1 - Näther, Niko A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Towards a multi-sensor system for the evaluation of aseptic processes employing hydrogen peroxide vapour (H2O2) JF - Physica status solidi (a) : applications and material science. 208 (2011), H. 6 Y1 - 2011 SN - 1862-6319 SP - 1351 EP - 1356 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Reisert, Steffen A1 - Geissler, H. A1 - Weiler, C. A1 - Wagner, P. A1 - Schöning, Michael Josef T1 - Multiple sensor-type system for monitoring the microbicidal effectiveness of aseptic sterilisation processes JF - Food control N2 - The present work describes a novel multiple sensor-type system for the real-time analysis of aseptic sterilisation processes employing gaseous hydrogen peroxide (H2O2) as a sterilant. The inactivation kinetics of Bacillus atrophaeus by gaseous H2O2 have been investigated by means of a methodical calibration experiment, taking into account the process variables H2O2 concentration, humidity and gas temperature. It has been found that the microbicidal effectiveness at H2O2 concentrations above 2% v/v is largely determined by the concentration itself, while at lower H2O2 concentrations, the gas temperature and humidity play a leading role. Furthermore, the responses of different types of gas sensors towards the influencing factors of the sterilisation process have been analysed within the same experiment. Based on a correlation established between the inactivation kinetics and the sensor responses, a calorimetric H2O2 sensor and a metal-oxide semiconductor (MOX) sensor have been identified as possible candidates for monitoring the microbicidal effectiveness of aseptic sterilisation processes employing gaseous H2O2. Therefore, two linear models that describe the relationship between sensor response and microbicidal effectiveness have been proposed. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.foodcont.2014.07.063 SN - 1873-7129 (E-Journal); 0956-7135 (Print) VL - 47 SP - 615 EP - 622 ER - TY - JOUR A1 - Reisert, Steffen A1 - Geissler, H. A1 - Florke, R. A1 - Wagner, P. A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Controlling aseptic sterilization processes by means of a multi-sensor system Y1 - 2011 N1 - 2011 IEEE Workshop on Merging Fields of Computational Intelligence and Sensor Technology ; 11.-15. April 2011 Paris, France SP - 18 EP - 22 PB - IEEE CY - New York ER - TY - JOUR A1 - Rachinger, Michael A1 - Bauch, Melanie A1 - Strittmatter, Axel A1 - Bongaerts, Johannes A1 - Evers, Stefan A1 - Maurer, Karl-Heinz A1 - Daniel, Rolf A1 - Liebl, Wolfgang A1 - Liesegang, Heiko A1 - Ehrenreich, Armin T1 - Size unlimited markerless deletions by a transconjugative plasmid-system in Bacillus licheniformis JF - Journal of biotechnology Y1 - 2013 SN - 1873-4863 (E-Journal); 0168-1656 (Print) VL - Vol. 164 IS - Iss. 4 SP - 365 EP - 369 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Rabehi, Amine A1 - Garlan, Benjamin A1 - Achtsnicht, Stefan A1 - Krause, Hans-Joachim A1 - Offenhäusser, Andreas A1 - Ngo, Kieu A1 - Neveu, Sophie A1 - Graff-Dubois, Stephanie A1 - Kokabi, Hamid T1 - Magnetic detection structure for Lab-on-Chip applications based on the frequency mixing technique JF - Sensors N2 - A magnetic frequency mixing technique with a set of miniaturized planar coils was investigated for use with a completely integrated Lab-on-Chip (LoC) pathogen sensing system. The system allows the detection and quantification of superparamagnetic beads. Additionally, in terms of magnetic nanoparticle characterization ability, the system can be used for immunoassays using the beads as markers. Analytical calculations and simulations for both excitation and pick-up coils are presented; the goal was to investigate the miniaturization of simple and cost-effective planar spiral coils. Following these calculations, a Printed Circuit Board (PCB) prototype was designed, manufactured, and tested for limit of detection, linear response, and validation of theoretical concepts. Using the magnetic frequency mixing technique, a limit of detection of 15 µg/mL of 20 nm core-sized nanoparticles was achieved without any shielding. KW - Lab-on-Chip KW - magnetic sensing KW - frequency mixing KW - superparamagnetic nanoparticles KW - magnetic beads Y1 - 2018 U6 - http://dx.doi.org/10.3390/s18061747 SN - 1424-8220 VL - 18 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Pourshahidi, Ali Mohammad A1 - Engelmann, Ulrich M. A1 - Offenhäusser, Andreas A1 - Krause, Hans-Joachim T1 - Resolving ambiguities in core size determination of magnetic nanoparticles from magnetic frequency mixing data JF - Journal of Magnetism and Magnetic Materials N2 - Frequency mixing magnetic detection (FMMD) has been widely utilized as a measurement technique in magnetic immunoassays. It can also be used for the characterization and distinction (also known as “colourization”) of different types of magnetic nanoparticles (MNPs) based on their core sizes. In a previous work, it was shown that the large particles contribute most of the FMMD signal. This leads to ambiguities in core size determination from fitting since the contribution of the small-sized particles is almost undetectable among the strong responses from the large ones. In this work, we report on how this ambiguity can be overcome by modelling the signal intensity using the Langevin model in thermodynamic equilibrium including a lognormal core size distribution fL(dc,d0,σ) fitted to experimentally measured FMMD data of immobilized MNPs. For each given median diameter d0, an ambiguous amount of best-fitting pairs of parameters distribution width σ and number of particles Np with R2 > 0.99 are extracted. By determining the samples’ total iron mass, mFe, with inductively coupled plasma optical emission spectrometry (ICP-OES), we are then able to identify the one specific best-fitting pair (σ, Np) one uniquely. With this additional externally measured parameter, we resolved the ambiguity in core size distribution and determined the parameters (d0, σ, Np) directly from FMMD measurements, allowing precise MNPs sample characterization. Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.jmmm.2022.169969 SN - 0304-8853 VL - 563 IS - In progress, Art. No. 169969 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pourshahidi, Ali Mohammad A1 - Achtsnicht, Stefan A1 - Offenhäusser, Andreas A1 - Krause, Hans-Joachim ED - Offenhäusser, Andreas T1 - Frequency Mixing Magnetic Detection Setup Employing Permanent Ring Magnets as a Static Offset Field Source JF - Sensors N2 - Frequency mixing magnetic detection (FMMD) has been explored for its applications in fields of magnetic biosensing, multiplex detection of magnetic nanoparticles (MNP) and the determination of core size distribution of MNP samples. Such applications rely on the application of a static offset magnetic field, which is generated traditionally with an electromagnet. Such a setup requires a current source, as well as passive or active cooling strategies, which directly sets a limitation based on the portability aspect that is desired for point of care (POC) monitoring applications. In this work, a measurement head is introduced that involves the utilization of two ring-shaped permanent magnets to generate a static offset magnetic field. A steel cylinder in the ring bores homogenizes the field. By variation of the distance between the ring magnets and of the thickness of the steel cylinder, the magnitude of the magnetic field at the sample position can be adjusted. Furthermore, the measurement setup is compared to the electromagnet offset module based on measured signals and temperature behavior. KW - magnetic sensors KW - biosensors KW - frequency mixing magnetic detection KW - magnetic nanoparticles Y1 - 2022 U6 - http://dx.doi.org/10.3390/s22228776 SN - 1424-8220 VL - 22 IS - 22 PB - MDPI CY - Basel ER - TY - JOUR A1 - Pourshahidi, Ali Mohammad A1 - Achtsnicht, Stefan A1 - Nambipareechee, Mrinal Murali A1 - Offenhäusser, Andreas A1 - Krause, Hans-Joachim T1 - Multiplex detection of magnetic beads using offset field dependent frequency mixing magnetic detection JF - Sensors N2 - Magnetic immunoassays employing Frequency Mixing Magnetic Detection (FMMD) have recently become increasingly popular for quantitative detection of various analytes. Simultaneous analysis of a sample for two or more targets is desirable in order to reduce the sample amount, save consumables, and save time. We show that different types of magnetic beads can be distinguished according to their frequency mixing response to a two-frequency magnetic excitation at different static magnetic offset fields. We recorded the offset field dependent FMMD response of two different particle types at frequencies ƒ₁ + n⋅ƒ₂, n = 1, 2, 3, 4 with ƒ₁ = 30.8 kHz and ƒ₂ = 63 Hz. Their signals were clearly distinguishable by the locations of the extremes and zeros of their responses. Binary mixtures of the two particle types were prepared with different mixing ratios. The mixture samples were analyzed by determining the best linear combination of the two pure constituents that best resembled the measured signals of the mixtures. Using a quadratic programming algorithm, the mixing ratios could be determined with an accuracy of greater than 14%. If each particle type is functionalized with a different antibody, multiplex detection of two different analytes becomes feasible. KW - colorization KW - multiplex detection KW - frequency mixing magnetic detection KW - magnetic nanoparticles Y1 - 2021 U6 - http://dx.doi.org/10.3390/s21175859 SN - 1424-8220 N1 - This article belongs to the Special Issue "Advanced Nanomaterial-Based Sensors for Biomedical Applications" VL - 21 IS - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Polen, T. A1 - Krämer, Marco A1 - Bongaerts, Johannes A1 - Wubbolts, Marcel A1 - Wendisch, V. F. T1 - The global gene expression response of Escherichia coli to L-phenylalanine JF - Journal of biotechnology Y1 - 2005 SN - 1873-4863 (E-Journal); 0168-1656 (Print) VL - Vol. 115 IS - Iss. 3 SP - 221 EP - 237 ER - TY - JOUR A1 - Poghossian, Arshak A1 - Yoshinobu, Tatsuo A1 - Simonis, A. A1 - Ecken, H. A1 - Lüth, Hans A1 - Schöning, Michael Josef T1 - Penicillin detection by means of field-effect based sensors: EnFET, capacitive EIS sensor or LAPS? JF - Sensors and Actuators B. 78 (2001), H. 1-3 Y1 - 2001 SN - 0925-4005 SP - 237 EP - 242 ER - TY - JOUR A1 - Poghossian, Arshak A1 - Yoshinobu, Tatsuo A1 - Schöning, Michael Josef T1 - Flow-velocity microsensors based on semiconductor field-effect structures JF - Sensors. 3 (2003), H. 7 Y1 - 2003 SN - 1424-8220 SP - 202 EP - 212 ER - TY - JOUR A1 - Poghossian, Arshak A1 - Yoshinobu, T. A1 - Simonis, A. A1 - Ecken, H. A1 - Lüth, H. A1 - Schöning, Michael Josef T1 - Penicillin detection by means of field-effect based sensors: EnFET, capacitive EIS sensor or LAPS? JF - Proceedings : Copenhagen, Denmark, 27 - 30 August 2000 / [ed.: R. de Reus ...] Y1 - 2000 SN - 87-89935-50-0 N1 - Eurosensors ; (14, 2000, København) ; Eurosensors ; (14 : ; 2000.08.27-30 : ; Copenhagen) ; European Conference on Solid-State Transducers ; (14 : ; 2000.08.27-30 : ; Copenhagen) SP - 27 EP - 30 PB - MIC, Mikroelektronik Centret CY - Lyngby, Denmark ER - TY - JOUR A1 - Poghossian, Arshak A1 - Werner, Frederik A1 - Buniatyan, V. V. A1 - Wagner, Torsten A1 - Miamoto, K. A1 - Yoshinobu, T. A1 - Schöning, Michael Josef T1 - Towards addressability of light-addressable potentiometric sensors: Shunting effect of non-illuminated region and cross-talk JF - Sensor and Actuators B: Chemical N2 - 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. Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.snb.2017.01.047 SN - 0925-4005 IS - 244 SP - 1071 EP - 1079 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Poghossian, Arshak A1 - Welden, Rene A1 - Buniatyan, Vahe V. A1 - Schöning, Michael Josef T1 - An Array of On-Chip Integrated, Individually Addressable Capacitive Field-Effect Sensors with Control Gate: Design and Modelling JF - Sensors N2 - The on-chip integration of multiple biochemical sensors based on field-effect electrolyte-insulator-semiconductor capacitors (EISCAP) is challenging due to technological difficulties in realization of electrically isolated EISCAPs on the same Si chip. In this work, we present a new simple design for an array of on-chip integrated, individually electrically addressable EISCAPs with an additional control gate (CG-EISCAP). The existence of the CG enables an addressable activation or deactivation of on-chip integrated individual CG-EISCAPs by simple electrical switching the CG of each sensor in various setups, and makes the new design capable for multianalyte detection without cross-talk effects between the sensors in the array. The new designed CG-EISCAP chip was modelled in so-called floating/short-circuited and floating/capacitively-coupled setups, and the corresponding electrical equivalent circuits were developed. In addition, the capacitance-voltage curves of the CG-EISCAP chip in different setups were simulated and compared with that of a single EISCAP sensor. Moreover, the sensitivity of the CG-EISCAP chip to surface potential changes induced by biochemical reactions was simulated and an impact of different parameters, such as gate voltage, insulator thickness and doping concentration in Si, on the sensitivity has been discussed. KW - equivalent circuit KW - multianalyte detection KW - control gate KW - on-chip integrated addressable EISCAP sensors KW - capacitive field-effect sensor Y1 - 2021 U6 - http://dx.doi.org/10.3390/s21186161 SN - 1424-8220 N1 - This article belongs to the Special Issue "Field-Effect Sensors: From pH Sensing to Biosensing" VL - 21 IS - 18 SP - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Poghossian, Arshak A1 - Weil, M. H. A1 - Bäcker, Matthias A1 - Mayer, D. A1 - Schöning, Michael Josef T1 - Field-effect Devices Functionalised with Gold-Nanoparticle/Macromolecule Hybrids: New Opportunities for a Label-Free Biosensing JF - Procedia Engineering N2 - Field-effect capacitive electrolyte-insulator-semiconductor (EIS) sensors functionalised with citrate-capped gold nanoparticles (AuNP) have been used for the electrostatic detection of macromolecules by their intrinsic molecular charge. The EIS sensor detects the charge changes in the AuNP/macromolecule hybrids induced by the adsorption or binding events. A feasibility of the proposed detection scheme has been exemplary demonstrated by realising EIS sensors for the detection of poly-D-lysine molecules. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.proeng.2012.09.136 SN - 1877-7058 N1 - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012" IS - 47 SP - 273 EP - 276 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Poghossian, Arshak A1 - Weil, M. A1 - Cherstvy, A. G. A1 - Schöning, Michael Josef T1 - Electrical monitoring of polyelectrolyte multilayer formation by means of capacitive field-effect devices JF - Analytical and bioanalytical chemistry N2 - The semiconductor field-effect platform represents a powerful tool for detecting the adsorption and binding of charged macromolecules with direct electrical readout. In this work, a capacitive electrolyte–insulator–semiconductor (EIS) field-effect sensor consisting of an Al-p-Si-SiO2 structure has been applied for real-time in situ electrical monitoring of the layer-by-layer formation of polyelectrolyte (PE) multilayers (PEM). The PEMs were deposited directly onto the SiO2 surface without any precursor layer or drying procedures. Anionic poly(sodium 4-styrene sulfonate) and cationic weak polyelectrolyte poly(allylamine hydrochloride) have been chosen as a model system. The effect of the ionic strength of the solution, polyelectrolyte concentration, number and polarity of the PE layers on the characteristics of the PEM-modified EIS sensors have been studied by means of capacitance–voltage and constant-capacitance methods. In addition, the thickness, surface morphology, roughness and wettabilityof the PE mono- and multilayers have been characterised by ellipsometry, atomic force microscopy and water contact-angle methods, respectively. To explain potential oscillations on the gate surface and signal behaviour of the capacitive field-effect EIS sensor modified with a PEM, a simplified electrostatic model that takes into account the reduced electrostatic screening of PE charges by mobile ions within the PEM has been proposed and discussed. Y1 - 2013 U6 - http://dx.doi.org/10.1007/s00216-013-6951-9 SN - 1432-1130 ; 1618-2642 VL - 405 IS - 20 SP - 6425 EP - 6436 PB - Springer CY - Berlin ER - TY - JOUR A1 - Poghossian, Arshak A1 - Wagner, Holger A1 - Schöning, Michael Josef T1 - Functional testing and characterisation of (bio-)chemical sensors on wafer level JF - Procedia Chemistry. 1 (2009), H. 1 Y1 - 2009 SN - 1876-6196 N1 - Proceedings of the Eurosensors XXIII conference ; Eurosensors 23 SP - 835 EP - 838 ER - TY - JOUR A1 - Poghossian, Arshak A1 - Wagner, Holger A1 - Schöning, Michael Josef T1 - Functional testing and characterisation of (bio-)chemical sensors on wafer level JF - Sensors and Actuators B: Chemical. 154 (2011), H. 2 Y1 - 2011 SN - 1873-3077 N1 - EUROSENSORS XXIII SP - 169 EP - 173 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Poghossian, Arshak A1 - Thust, M. A1 - Schöning, Michael Josef A1 - Müller-Veggian, Mattea A1 - Kordos, P. A1 - Lüth, H. T1 - Cross-sensitivity of a capacitive penicillin sensor combined with a diffusion barrier JF - Sensors and Actuators B. 68 (2000), H. 1-3 Y1 - 2000 SN - 0925-4005 SP - 260 EP - 265 ER - TY - JOUR A1 - Poghossian, Arshak A1 - Thust, M. A1 - Schroth, P. A1 - Steffen, A. A1 - Lüth, H. A1 - Schöning, Michael Josef T1 - Penicillin detection by means of silicon-based field-effect structures JF - Sensors and Materials. 13 (2001), H. 4 Y1 - 2001 SN - 0392-2510 SP - 207 EP - 223 ER - TY - JOUR A1 - Poghossian, Arshak A1 - Schöning, Michael Josef A1 - Schroth, P. A1 - Simonis, A. A1 - Lüth, H. T1 - An ISFET-based penicillin sensor with high sensitivity, low detection limit and long lifetime JF - Sensors and Actuators B. 76 (2001), H. 1-3 Y1 - 2001 SN - 0925-4005 SP - 519 EP - 526 ER -