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 - 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 - Siegert, Petra A1 - McLeish, Michael J. A1 - Baumann, Martin A1 - Iding, Hans A1 - Kneen, Malea M. A1 - Kenyon, George L. A1 - Pohl, Martina T1 - Exchanging the substrate specificities of pyruvate decarboxylase from Zymomonas mobilis and benzoylformate decarboxylase from Pseudomonas putida JF - Protein engineering, design, and selection : peds Y1 - 2005 SN - 1460-213X (E-Journal); 1741-0134 (E-Journal); 0269-2139 (Print); 1741-0126 (Print) VL - Vol. 18 IS - Iss. 7 SP - 345 EP - 357 ER - TY - JOUR A1 - Bäcker, Matthias A1 - Schusser, Sebastian A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Multi-Parametererfassung mit siliziumbasiertem Sensorchip: Aus Drei mach Eins JF - GIT Labor-Fachzeitschrift Y1 - 2014 SN - 0016-3538 IS - 2 SP - 28 EP - 30 PB - Wiley ER - TY - JOUR A1 - Handtke, Stefan A1 - Volland, Sonja A1 - Methling, Karen A1 - Albrecht, Dirk A1 - Becher, Dörte A1 - Nehls, Jenny A1 - Bongaerts, Johannes A1 - Maurer, Karl-Heinz A1 - Lalk, Michael A1 - Liesegang, Heiko A1 - Voigt, Birgit A1 - Daniel, Rolf A1 - Hecker, Michael T1 - Cell physiology of the biotechnological relevant bacterium Bacillus pumilus - An omics-based approach JF - Journal of Biotechnology N2 - Members of the species Bacillus pumilus get more and more in focus of the biotechnological industry as potential new production strains. Based on exoproteome analysis, B. pumilus strain Jo2, possessing a high secretion capability, was chosen for an omics-based investigation. The proteome and metabolome of B. pumilus cells growing either in minimal or complex medium was analyzed. In total, 1542 proteins were identified in growing B. pumilus cells, among them 1182 cytosolic proteins, 297 membrane and lipoproteins and 63 secreted proteins. This accounts for about 43% of the 3616 proteins encoded in the B. pumilus Jo2 genome sequence. By using GC–MS, IP-LC/MS and H NMR methods numerous metabolites were analyzed and assigned to reconstructed metabolic pathways. In the genome sequence a functional secretion system including the components of the Sec- and Tat-secretion machinery was found. Analysis of the exoproteome revealed secretion of about 70 proteins with predicted secretion signals. In addition, selected production-relevant genome features such as restriction modification systems and NRPS clusters of B. pumilus Jo2 are discussed. Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.jbiotec.2014.08.028 SN - 1873-4863 (E-Journal); 0168-1656 (Print) IS - 192(A) SP - 204 EP - 214 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Recent developments of chemical imaging sensor systems based on the principle of the light-addressable potentiometric sensor JF - Sensors and actuators B: Chemical N2 - The light-addressable potentiometric sensor (LAPS) is an electrochemical sensor with a field-effect structure to detect the variation of the Nernst potential at its sensor surface, the measured area on which is defined by illumination. Thanks to this light-addressability, the LAPS can be applied to chemical imaging sensor systems, which can visualize the two-dimensional distribution of a particular target ion on the sensor surface. Chemical imaging sensor systems are expected to be useful for analysis of reaction and diffusion in various electrochemical and biological samples. Recent developments of LAPS-based chemical imaging sensor systems, in terms of the spatial resolution, measurement speed, image quality, miniaturization and integration with microfluidic devices, are summarized and discussed. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.snb.2014.09.002 SN - 1873-3077 (E-Journal); 0925-4005 (Print) VL - 207, Part B SP - 926 EP - 932 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Siqueira, Jose R. A1 - Molinnus, Denise A1 - Beging, Stefan A1 - Schöning, Michael Josef T1 - Incorporating a hybrid urease-carbon nanotubes sensitive nanofilm on capacitive field-effect sensors for urea detection JF - Analytical chemistry N2 - The ideal combination among biomolecules and nanomaterials is the key for reaching biosensing units with high sensitivity. The challenge, however, is to find out a stable and sensitive film architecture that can be incorporated on the sensor’s surface. In this paper, we report on the benefits of incorporating a layer-by-layer (LbL) nanofilm of polyamidoamine (PAMAM) dendrimer and carbon nanotubes (CNTs) on capacitive electrolyte-insulator-semiconductor (EIS) field-effect sensors for detecting urea. Three sensor arrangements were studied in order to investigate the adequate film architecture, involving the LbL film with the enzyme urease: (i) urease immobilized directly onto a bare EIS [EIS-urease] sensor; (ii) urease atop the LbL film over the EIS [EIS-(PAMAM/CNT)-urease] sensor; and (iii) urease sandwiched between the LbL film and another CNT layer [EIS-(PAMAM/CNT)-urease-CNT]. The surface morphology of all three urea-based EIS biosensors was investigated by atomic force microscopy (AFM), while the biosensing abilities were studied by means of capacitance–voltage (C/V) and dynamic constant-capacitance (ConCap) measureaments at urea concentrations ranging from 0.1 mM to 100 mM. The EIS-urease and EIS-(PAMAM/CNT)-urease sensors showed similar sensitivity (∼18 mV/decade) and a nonregular signal behavior as the urea concentration increased. On the other hand, the EIS-(PAMAM/CNT)-urease-CNT sensor exhibited a superior output signal performance and higher sensitivity of about 33 mV/decade. The presence of the additional CNT layer was decisive to achieve a urea based EIS sensor with enhanced properties. Such sensitive architecture demonstrates that the incorporation of an adequate hybrid enzyme-nanofilm as sensing unit opens new prospects for biosensing applications using the field-effect sensor platform. Y1 - 2014 U6 - http://dx.doi.org/10.1021/ac500458s SN - 1520-6882 (E-Journal); 0003-2700 (Print); 0096-4484 (Print) VL - 86 IS - 11 SP - 5370 EP - 5375 PB - ACS Publications CY - Columbus ER - TY - JOUR A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Mayer, Dirk A1 - Schöning, Michael Josef T1 - Gating capacitive field-effect sensors by the charge of nanoparticle/molecule hybrids JF - Nanoscale Y1 - 2015 U6 - http://dx.doi.org/10.1039/C4NR05987E SN - 2040-3372 (E-Journal); 2040-3364 (Print) SP - 1023 EP - 1031 PB - Royal Society of Chemistry (RSC) CY - Cambridge ER - TY - JOUR A1 - Schusser, Sebastian A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Krischer, M. A1 - Leinhos, Marcel A1 - Wagner, P. A1 - Schöning, Michael Josef T1 - An application of field-effect sensors for in-situ monitoring of degradation of biopolymers JF - Sensors and actuators B: Chemical N2 - The characterization of the degradation kinetics of biodegradable polymers is mandatory with regard to their proper application. In the present work, polymer-modified electrolyte–insulator–semiconductor (PMEIS) field-effect sensors have been applied for in-situ monitoring of the pH-dependent degradation kinetics of the commercially available biopolymer poly(d,l-lactic acid) (PDLLA) in buffer solutions from pH 3 to pH 13. PDLLA films of 500 nm thickness were deposited on the surface of an Al–p-Si–SiO2–Ta2O5 structure from a polymer solution by means of spin-coating method. The PMEIS sensor is, in principle, capable to detect any changes in bulk, surface and interface properties of the polymer induced by degradation processes. A faster degradation has been observed for PDLLA films exposed to alkaline solutions (pH 9, pH 11 and pH 13). Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.snb.2014.10.058 SN - 1873-3077 (E-Journal); 0925-4005 (Print) VL - 207, Part B SP - 954 EP - 959 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, K. A1 - Seki, K. A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, T. T1 - Enhancement of the spatial resolution of the chemical imaging sensor by a hybrid fiber-optic illumination JF - Procedia Engineering N2 - The chemical imaging sensor, which is based on the principle of the light-addressable potentiometric sensor (LAPS), is a powerful tool to visualize the spatial distribution of chemical species on the sensor surface. The spatial resolution of this sensor depends on the diffusion of photocarriers excited by a modulated light. In this study, a novel hybrid fiber-optic illumination was developed to enhance the spatial resolution. It consists of a modulated light probe to generate a photocurrent signal and a ring of constant light, which suppresses the lateral diffusion of minority carriers excited by the modulated light. It is demonstrated that the spatial resolution was improved from 92 μm to 68 μm. Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.proeng.2014.11.563 SN - 1877-7058 N1 - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014> VL - 87 SP - 612 EP - 615 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Murib, M. S. A1 - Yeap, W. S. A1 - Martens, D. A1 - Liu, X. A1 - Bienstman, P. A1 - Fahlman, M. A1 - Schöning, Michael Josef A1 - Michiels, L. A1 - Haenen, K. A1 - Serpengüzel, A. A1 - Wagner, Patrick T1 - Photonic studies on polymer-coated sapphire-spheres : a model system for biological ligands JF - Sensors and actuators A: Physical N2 - In this study we show an optical biosensor concept, based on elastic light scattering from sapphire microspheres. Transmitted and elastic scattering intensity of the microspheres (radius 500 μm, refractive index 1.77) on an optical fiber half coupler is analyzed at 1510 nm. The 0.43 nm angular mode spacing of the resonances is comparable to the angular mode spacing value estimated using the optical size of the microsphere. The spectral linewidths of the resonances are in the order of 0.01 nm, which corresponds to quality factors of approximately 105. A polydopamine layer is used as a functionalizing agent on sapphire microspherical resonators in view of biosensor implementation. The varying layer thickness on the microsphere is determined as a function of the resonance wavelength shift. It is shown that polymer functionalization has a minor effect on the quality factor. This is a promising step toward the development of an optical biosensor. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.sna.2014.11.024 SN - 1873-3069 (E-Journal); 0924-4247 (Print) VL - 222 SP - 212 EP - 219 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schöning, Michael Josef A1 - Bäcker, Matthias T1 - Chip-basierte Sensoren für die Biotechnik Y1 - 2012 SN - 1611-0854 N1 - 4 Seiten VL - 13 IS - 2 PB - BIOCOM CY - Berlin ER - TY - JOUR A1 - Schöning, Michael Josef A1 - Poghossian, Arshak T1 - BioFEDs (field-effect devices) : State-of-the-art and new directions JF - Electroanalysis Y1 - 2006 U6 - http://dx.doi.org/10.1002/elan.200603609 SN - 1521-4109 VL - 18 IS - 19-20 SP - 1893 EP - 1900 ER - TY - JOUR A1 - Spelthahn, Heiko A1 - Schubert, Jürgen A1 - Schöning, Michael Josef T1 - Dünnschichtsensoren für die Schwermetallanalytik : Mikroelektroden auf Chalkogenidglasbasis JF - GIT Labor-Fachzeitschrift N2 - Die Detektion von Schadstoffen repräsentiert in der Umweltanalytik eine wichtige Aufgabenstellung. Gerade die Abwasser- bzw. Brauchwasseranalytik sowie die Prozesskontrolle haben einen hohen Stellenwert. Siliziumbasierte Dünnschichtsensoren bieten eine kostengünstige Möglichkeit, „online“-Messungen bzw. Vor-Ort-Messungen zeitnah durchzuführen. In dieser Arbeit wird ein potentiometrisches Sensorarray auf der Basis von Chalkogenidgläsern zur Detektion von Schwermetallen in wässrigen Medien vorgestellt. Y1 - 2012 IS - 4 SP - 285 EP - 287 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wu, Chunsheng A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Werner, Frederik A1 - Schöning, Michael Josef T1 - Label-free detection of DNA using light-addressable potentiometric sensor modified with a positively charged polyelectrolyte layer JF - Nanoscale N2 - A multi-spot (16 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al–p-Si–SiO2 structure modified with a weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. To achieve a preferentially flat orientation of DNA strands and thus, to reduce the distance between the DNA charge and MLAPS surface, the negatively charged probe single-stranded DNAs (ssDNA) were electrostatically adsorbed onto the positively charged PAH layer using a simple layer-by-layer (LbL) technique. In this way, more DNA charge can be positioned within the Debye length, yielding a higher sensor signal. The surface potential changes in each spot induced due to the surface modification steps (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), non-specific adsorption of mismatched ssDNA) were determined from the shifts of photocurrent–voltage curves along the voltage axis. A high sensor signal of 83 mV was registered after immobilization of probe ssDNA onto the PAH layer. The hybridization signal increases from 5 mV to 32 mV with increasing the concentration of cDNA from 0.1 nM to 5 μM. In contrast, a small signal of 5 mV was recorded in the case of non-specific adsorption of fully mismatched ssDNA (5 μM). The obtained results demonstrate the potential of the MLAPS in combination with the simple and rapid LbL immobilization technique as a promising platform for the future development of multi-spot light-addressable label-free DNA chips with direct electrical readout. Y1 - 2015 U6 - http://dx.doi.org/10.1039/C4NR07225A VL - 14 IS - 7 SP - 6143 EP - 6150 PB - Royal Society of Chemistry (RSC) CY - Cambridge ER - TY - JOUR A1 - Beging, Stefan A1 - Leinhos, Marcel A1 - Jablonski, Melanie A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Studying the spatially resolved immobilisation of enzymes on a capacitive field-effect structure by means of nano-spotting JF - Physica status solidi (a) Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431891 SN - 1862-6319 VL - 212 IS - 6 SP - 1353 EP - 1358 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Poghossian, Arshak A1 - Katz, Evgeny A1 - Schöning, Michael Josef T1 - Enzyme logic AND-Reset and OR-Reset gates based on a field-effect electronic transducer modified with multi-enzyme membrane JF - Chemical Communications N2 - Capacitive field-effect sensors modified with a multi-enzyme membrane have been applied for an electronic transduction of biochemical signals processed by enzyme-based AND-Reset and OR-Reset logic gates. The local pH change at the sensor surface induced by the enzymatic reaction was used for the activation of the Reset function for the first time. Y1 - 2015 U6 - http://dx.doi.org/10.1039/C5CC01362C VL - 51 SP - 6564 EP - 6567 PB - Royal Society of Chemistry (RSC) CY - Cambridge ER - TY - JOUR A1 - Oberländer, Jan A1 - Bromm, Alexander A1 - Wendeler, Luisa A1 - Iken, Heiko A1 - Palomar Duran, Marlena A1 - Greeff, Anton A1 - Kirchner, Patrick A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Towards a biosensor to monitor the sterilisation efficiency of aseptic filling machines JF - Physica status solidi (a) N2 - Sterilisation processes are compulsory in medicine, pharmacy, and food industries to prevent infections of consumers and microbiological contaminations of products. Monitoring the sterilisation by conventional microbiological methods is time- and lab-consuming. To overcome this problem, in this work a novel biosensor has been proposed. The sensor enables a fast method to evaluate sterilisation processes. By means of thin-film technology the sensor's transducer structures in form of IDEs (interdigitated electrodes) have been fabricated on a silicon substrate. Physical characterisation of the developed sensor was done by AFM, SEM, and profilometry. Impedance analyses were conducted for the electrical characterisation. As microbiological layer spores of B. atrophaeus have been immobilised on the sensing structure; spores of this type are a well-known sterilisation test organism. Impedance measurements at a fixed frequency over time were performed to monitor the immobilisation process. A sterilisation process according to aseptic filling machines was applied to demonstrate the sensor functionality. After both, immobilisation and sterilisation, a change in impedance could successfully be detected. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431900 SN - 1862-6319 VL - 212 IS - 6 SP - 1299 EP - 1305 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Reisert, Steffen A1 - Kramer, Friederike A1 - Begoyan, Vardges K. A1 - Buniatyan, Vahe V. A1 - Schöning, Michael Josef T1 - Multi-parameter sensing using high-k oxide of barium strontium titanate JF - Physica status solidi (a) N2 - High-k perovskite oxide of barium strontium titanate (BST) represents a very attractive multi-functional transducer material for the development of (bio-)chemical sensors. In this work, a Si-based sensor chip containing Pt interdigitated electrodes covered with a thin BST layer (485 nm) has been developed for multi-parameter chemical sensing. The chip has been applied for the contactless measurement of the electrolyte conductivity, the detection of adsorbed charged macromolecules (positively charged polyelectrolytes of polyethylenimine) and the concentration of hydrogen peroxide (H2O2) vapor. The experimental results of functional testing of individual sensors are presented. The mechanism of the BST sensitivity to charged polyelectrolytes and H2O2 vapor has been proposed and discussed. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431911 SN - 1862-6319 VL - 212 IS - 6 SP - 1259 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Pieper, Martin T1 - Simulating the electromagnetic‐thermal treatment of thin aluminium layers for adhesion improvement JF - Physica status solidi (a) N2 - A composite layer material used in packaging industry is made from joining layers of different materials using an adhesive. An important processing step in the production of aluminium-containing composites is the surface treatment and consequent coating of adhesive material on the aluminium surface. To increase adhesion strength between aluminium layer and the adhesive material, the foil is heat treated. For efficient heating, induction heating was considered as state-of-the-art treatment process. Due to the complexity of the heating process and the unpredictable nature of the heating source, the control of the process is not yet optimised. In this work, a finite element analysis of the process was established and various process parameters were studied. The process was simplified and modelled in 3D. The numerical model contains an air domain, an aluminium layer and a copper coil fitted with a magnetic field concentrating material. The effect of changing the speed of the aluminium foil (or rolling speed) was studied with the change of the coil current. Statistical analysis was used for generating a general control equation of coil current with changing rolling speed. Y1 - 2015 U6 - http://dx.doi.org/10.1002/pssa.201431893 SN - 1862-6319 VL - Vol. 212 IS - 6 SP - 1234 EP - 1241 PB - Wiley CY - Weinheim ER -