TY - JOUR A1 - Bohrn, U. A1 - Stütz, E. A1 - Fuchs, K. A1 - Fleischer, M. A1 - Schöning, Michael Josef A1 - Wagner, P. T1 - Monitoring of irritant gas using a whole-cell-based sensor system JF - Sensors and Actuators B: Chemical N2 - Cell-based sensors for the detection of gases have long been underrepresented, due to the cellular requirement of being cultured in a liquid environment. In this work we established a cell-based gas biosensor for the detection of toxic substances in air, by adapting a commercial sensor chip (Bionas®), previously used for the measurement of pollutants in liquids. Cells of the respiratory tract (A549, RPMI 2650, V79), which survive at a gas phase in a natural context, are used as biological receptors. The physiological cell parameters acidification, respiration and morphology are continuously monitored in parallel. Ammonia was used as a highly water-soluble model gas to test the feasibility of the sensor system. Infrared measurements confirmed the sufficiency of the medium draining method. This sensor system provides a basis for many sensor applications such as environmental monitoring, building technology and public security. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.snb.2012.05.088 SN - 0925-4005 VL - 175 SP - 208 EP - 217 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kurulgan Demirci, Eylem A1 - Demirci, Taylan A1 - Linder, Peter A1 - Trzewik, Jürgen A1 - Gierkowski, Jessica Ricarda A1 - Gossmann, Matthias A1 - Kayser, Peter A1 - Porst, Dariusz A1 - Digel, Ilya A1 - Artmann, Gerhard A1 - Temiz Artmann, Aysegül T1 - rhAPC reduces the endothelial cell permeability via a decrease of contractile tensions induced by endothelial cells JF - Journal of Bioscience and Bioengineering N2 - All cells generate contractile tension. This strain is crucial for mechanically controlling the cell shape, function and survival. In this study, the CellDrum technology quantifying cell's (the cellular) mechanical tension on a pico-scale was used to investigate the effect of lipopolysaccharide (LPS) on human aortic endothelial cell (HAoEC) tension. The LPS effect during gram-negative sepsis on endothelial cells is cell contraction causing endothelium permeability increase. The aim was to finding out whether recombinant activated protein C (rhAPC) would reverse the endothelial cell response in an in-vitro sepsis model. In this study, the established in-vitro sepsis model was confirmed by interleukin 6 (IL-6) levels at the proteomic and genomic levels by ELISA, real time-PCR and reactive oxygen species (ROS) activation by florescence staining. The thrombin cellular contraction effect on endothelial cells was used as a positive control when the CellDrum technology was applied. Additionally, the Ras homolog gene family, member A (RhoA) mRNA expression level was checked by real time-PCR to support contractile tension results. According to contractile tension results, the mechanical predominance of actin stress fibers was a reason of the increased endothelial contractile tension leading to enhanced endothelium contractility and thus permeability enhancement. The originality of this data supports firstly the basic measurement principles of the CellDrum technology and secondly that rhAPC has a beneficial effect on sepsis influenced cellular tension. The technology presented here is promising for future high-throughput cellular tension analysis that will help identify pathological contractile tension responses of cells and prove further cell in-vitro models. KW - Cell permeability KW - Cellular force KW - Endothelial cells KW - Recombinant activated protein C KW - Lipopolysaccharide KW - Contractile tension KW - CellDrum Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.jbiosc.2012.03.019 SN - 1347-4421 VL - 113 IS - 2 SP - 212 EP - 219 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kirchner, Patrick A1 - Reisert, Steffen A1 - Pütz, Patrick A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Characterisation of polymeric materials as passivation layer for calorimetric H2O2 gas sensors JF - Physica Status Solidi (a) N2 - Calorimetric gas sensors for monitoring the H₂O₂ concentration at elevated temperatures in industrial sterilisation processes have been presented in previous works. These sensors are built up in form of a differential set-up of a catalytically active and passive temperature-sensitive structure. Although, various types of catalytically active dispersions have been studied, the passivation layer has to be established and therefore, chemically as well as physically characterised. In the present work, fluorinated ethylene propylene (FEP), perfluoralkoxy (PFA) and epoxy-based SU-8 photoresist as temperature-stable polymeric materials have been investigated for sensor passivation in terms of their chemical inertness against H₂O₂, their hygroscopic properties as well as their morphology. The polymeric materials were deposited via spin-coating on the temperature-sensitive structure, wherein spin-coated FEP and PFA show slight agglomerates. However, they possess a low absorption of humidity due to their hydrophobic surface, whereas the SU-8 layer has a closed surface but shows a slightly higher absorption of water. All of them were inert against gaseous H₂O₂ during the characterisation in H₂O₂ atmosphere that demonstrates their suitability as passivation layer for calorimetric H₂O₂ gas sensors. Y1 - 2012 U6 - http://dx.doi.org/10.1002/pssa.201100773 SN - 1862-6319 VL - 209 IS - 5 SP - 859 EP - 863 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Spelthahn, Heiko A1 - Kirsanov, Dmitry A1 - Legin, Andrey A1 - Osterrath, Thomas A1 - Schubert, Jürgen A1 - Zander, Willi A1 - Schöning, Michael Josef T1 - Development of a thin-film sensor array for analytical monitoring of heavy metals in aqueous solutions JF - Physica Status Solidi (a) N2 - In industrial processes there is a variety of heavy metals (e.g., copper, zinc, cadmium, and lead) in use for wires, coatings, paints, alloys, batteries, etc. Since the application of these transition metals for industry is inevitable, it is a vital task to develop proper analytical techniques for their monitoring at low activity levels, especially because most of these elements are acutely toxic for biological organisms. The determination of ions in solution by means of a simple and inexpensive sensor array is, therefore, a promising task. In this work, a sensor array with heavy metal-sensitive chalcogenide glass membranes for the simultaneous detection of the four ions Ag⁺, Cu2⁺, Cd2⁺, and Pb2⁺ in solution is realized. The results of the physical characterization by means of microscopy, profilometry, Rutherford backscattering spectroscopy (RBS), and scanning electron microscopy (SEM) as well as the electrochemical characterization by means of potentiometric measurements are presented. Additionally, the possibility to expand the sensor array by polymeric sensor membranes is discussed. Y1 - 2012 SN - 1862-6319 U6 - http://dx.doi.org/10.1002/pssa.201100733 VL - 209 IS - 5 SP - 885 EP - 891 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Kaneko, Kazumi A1 - Matsuo, Akira A1 - Wagner, Torsten A1 - Kanoh, Shiníchiro A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Miniaturized chemical imaging sensor system using an OLED display panel JF - Sensors and Actuators B: Chemical N2 - The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the two-dimensional distribution of specific ions or molecules in the solution. In this study, we developed a miniaturized chemical imaging sensor system with an OLED display panel as a light source that scans the sensor plate. In the proposed configuration, the display panel is placed directly below the sensor plate and illuminates the back surface. The measured area defined by illumination can be arbitrarily customized to fit the size and the shape of the sample to be measured. The waveform of the generated photocurrent, the current–voltage characteristics and the pH sensitivity were investigated and pH imaging with this miniaturized system was demonstrated. KW - LAPS KW - Light-addressable potentiometric sensor KW - Chemical imaging sensor KW - Organic light-emitting diode display Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.snb.2011.02.029 SN - 0925-4005 N1 - Part of special issue "Eurosensors XXIV, 2010" VL - 170 SP - 82 EP - 87 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schusser, Sebastian A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Leinhos, Marcel A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Characterization of biodegradable polymers with capacitive field-effect sensors JF - Sensors and actuators B: Chemical N2 - In vitro studies of the degradation kinetic of biopolymers are essential for the design and optimization of implantable biomedical devices. In the presented work, a field-effect capacitive sensor has been applied for the real-time and in situ monitoring of degradation processes of biopolymers for the first time. The polymer-covered field-effect sensor is, in principle, capable to detect any changes in bulk, surface and interface properties of the polymer induced by degradation processes. The feasibility of this approach has been experimentally proven by using the commercially available biomedical polymer poly(D,L-lactic acid) (PDLLA) as a model system. PDLLA films of different thicknesses were deposited on the Ta₂O₅-gate surface of the field-effect structure from a polymer solution by means of spin-coating method. The polymer-modified field-effect sensors have been characterized by means of capacitance–voltage and impedance-spectroscopy method. The degradation of the PDLLA was accelerated by changing the degradation medium from neutral (pH 7.2) to alkaline (pH 9) condition, resulting in drastic changes in the capacitance and impedance spectra of the polymer-modified field-effect sensor. KW - Impedance spectroscopy KW - C–V method KW - Real-time monitoring KW - Poly(d,l-lacticacid) KW - (Bio)degradation KW - Field-effect sensor Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.snb.2012.07.099 SN - 0925-4005 N1 - Part of special issue "Selected Papers from the 14th International Meeting on Chemical Sensors" VL - 187 SP - 2 EP - 7 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Friedrich, Peter A1 - Berger, Jörg A1 - Rysstad, Gunnar A1 - Schöning, Michael Josef A1 - Keusgen, Michael T1 - Realisation of a calorimetric gas sensor on polyimide foil for applications in aseptic food industry JF - Sensors and Actuators B: Chemical N2 - A calorimetric gas sensor is presented for the monitoring of vapour-phase H2O2 at elevated temperature during sterilisation processes in aseptic food industry. The sensor was built up on a flexible polyimide foil (thickness: 25 μm) that has been chosen due to its thermal stability and low thermal conductivity. The sensor set-up consists of two temperature-sensitive platinum thin-film resistances passivated by a layer of SU-8 photo resist and catalytically activated by manganese(IV) oxide. Instead of an active heating structure, the calorimetric sensor utilises the elevated temperature of the evaporated H2O2 aerosol. In an experimental test rig, the sensor has shown a sensitivity of 4.78 °C/(%, v/v) in a H2O2 concentration range of 0%, v/v to 8%, v/v. Furthermore, the sensor possesses the same, unchanged sensor signal even at varied medium temperatures between 210 °C and 270 °C of the gas stream. At flow rates of the gas stream from 8 m3/h to 12 m3/h, the sensor has shown only a slightly reduced sensitivity at a low flow rate of 8 m3/h. The sensor characterisation demonstrates the suitability of the calorimetric gas sensor for monitoring the efficiency of industrial sterilisation processes. KW - Sterilisation process KW - Hydrogen peroxide KW - Polyimide KW - Calorimetric gas sensor Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.snb.2011.01.032 SN - 0925-4005 N1 - Part of special issue "Eurosensors XXIV, 2010" VL - 170 SP - 60 EP - 66 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Atlas, Glen A1 - Brealey, David A1 - Dhar, Sunil A1 - Dikta, Gerhard A1 - Singer, Meryvn T1 - Additional hemodynamic measurements with an esophageal Doppler monitor: a preliminary report of compliance, force, kinetic energy, and afterload in the clinical setting JF - Journal of clinical monitoring and computing N2 - The esophageal Doppler monitor (EDM) is a minimally-invasive hemodynamic device which evaluates both cardiac output (CO), and fluid status, by estimating stroke volume (SV) and calculating heart rate (HR). The measurement of these parameters is based upon a continuous and accurate approximation of distal thoracic aortic blood flow. Furthermore, the peak velocity (PV) and mean acceleration (MA), of aortic blood flow at this anatomic location, are also determined by the EDM. The purpose of this preliminary report is to examine additional clinical hemodynamic calculations of: compliance (C), kinetic energy (KE), force (F), and afterload (TSVRi). These data were derived using both velocity-based measurements, provided by the EDM, as well as other contemporaneous physiologic parameters. Data were obtained from anesthetized patients undergoing surgery or who were in a critical care unit. A graphical inspection of these measurements is presented and discussed with respect to each patient’s clinical situation. When normalized to each of their initial values, F and KE both consistently demonstrated more discriminative power than either PV or MA. The EDM offers additional applications for hemodynamic monitoring. Further research regarding the accuracy, utility, and limitations of these parameters is therefore indicated. KW - Acceleration KW - Velocity KW - Kinetic energy KW - Force KW - Compliance KW - Afterload KW - Contractility KW - Volume status KW - Esophageal Doppler monitor Y1 - 2012 SN - 1573-2614 U6 - http://dx.doi.org/10.1007/s10877-012-9386-5 IS - 26 SP - 473 EP - 482 PB - Springer Nature CY - London ER - TY - JOUR A1 - Bassam, Rasha A1 - Hescheler, Jürgen A1 - Temiz Artmann, Aysegül A1 - Artmann, Gerhard A1 - Digel, Ilya T1 - Effects of spermine NONOate and ATP on the thermal stability of hemoglobin JF - BMC Biophysics N2 - Background Minor changes in protein structure induced by small organic and inorganic molecules can result in significant metabolic effects. The effects can be even more profound if the molecular players are chemically active and present in the cell in considerable amounts. The aim of our study was to investigate effects of a nitric oxide donor (spermine NONOate), ATP and sodium/potassium environment on the dynamics of thermal unfolding of human hemoglobin (Hb). The effect of these molecules was examined by means of circular dichroism spectrometry (CD) in the temperature range between 25°C and 70°C. The alpha-helical content of buffered hemoglobin samples (0.1 mg/ml) was estimated via ellipticity change measurements at a heating rate of 1°C/min. Results Major results were: 1) spermine NONOate persistently decreased the hemoglobin unfolding temperature T u irrespectively of the Na + /K + environment, 2) ATP instead increased the unfolding temperature by 3°C in both sodium-based and potassium-based buffers and 3) mutual effects of ATP and NO were strongly influenced by particular buffer ionic compositions. Moreover, the presence of potassium facilitated a partial unfolding of alpha-helical structures even at room temperature. Conclusion The obtained data might shed more light on molecular mechanisms and biophysics involved in the regulation of protein activity by small solutes in the cell. KW - Nitric Oxide Donor KW - NONOate KW - Circular Dichroism KW - Nitric Oxide Y1 - 2012 U6 - http://dx.doi.org/10.1186/2046-1682-5-16 SN - 2046-1682 VL - 5 PB - BioMed Central CY - London ER - TY - JOUR A1 - Gutheil, Inge A1 - Berg, Tommy A1 - Grotendorst, Johannes T1 - Performance Analysis of Parallel Eigensolvers of two Libraries on BlueGene/P JF - Journal of Mathematics and Systems Science N2 - Many applications in computational science and engineering require the computation of eigenvalues and vectors of dense symmetric or Hermitian matrices. For example, in DFT (density functional theory) calculations on modern supercomputers 10% to 30% of the eigenvalues and eigenvectors of huge dense matrices have to be calculated. Therefore, performance and parallel scaling of the used eigensolvers is of upmost interest. In this article different routines of the linear algebra packages ScaLAPACK and Elemental for parallel solution of the symmetric eigenvalue problem are compared concerning their performance on the BlueGene/P supercomputer. Parameters for performance optimization are adjusted for the different data distribution methods used in the two libraries. It is found that for all test cases the new library Elemental which uses a two-dimensional element by element distribution of the matrices to the processors shows better performance than the old ScaLAPACK library which uses a block-cyclic distribution. KW - performance analysis KW - Elemental KW - ScaLAPACK KW - eigensolvers KW - Numerical linear algebra Y1 - 2012 U6 - http://dx.doi.org/10.17265/2159-5291/2012.04.003 SN - 2159-5291 VL - 2 IS - 4 SP - 231 EP - 236 PB - David Publishing CY - Libertyville ER -