TY - JOUR A1 - Bäcker, Matthias A1 - Kramer, F. A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Bratov, A. A1 - Abramova, N. A1 - Schöning, Michael Josef T1 - Planar and 3D interdigitated electrodes for biosensing applications: The impact of a dielectric barrier on the sensor properties JF - Physica Status Solidi (A) - Applications and Materials Science N2 - Planar and three-dimensional (3D) interdigitated electrodes (IDE) with electrode digits separated by an insulating barrier of different heights were electrochemically characterized and compared in terms of their sensing properties. Due to the impact of the surface resistance, both types of IDE structures display a non-linear behavior in low-ionic strength solutions. The experimental data were fitted to an electrical equivalent circuit and interpreted taking into account the surface-charge-governed properties. The effect of a charged polyelectrolyte layer electrostatically assembled onto the sensor surface on the surface resistance in solutions with different KCl concentration is studied. In case of the same electrode footprint, 3D-IDEs show a larger cell constant and a higher sensitivity to molecular adsorption than that of planar IDEs. The obtained results demonstrate the potential of 3D-IDEs as a new transducer structure for a direct label-free sensing of charged molecules. Y1 - 2014 U6 - http://dx.doi.org/10.1002/pssa.201330416 SN - 1521-396X (E-Journal); 1862-6319 (E-Journal); 0031-8965 (Print); 1862-6300 (Print) VL - 211 IS - 6 SP - 1357 EP - 1363 PB - Wiley-VCH CY - Weinheim 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 - Guo, Yuanyuan A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Theoretical study and simulation of light-addressable potentiometric sensors JF - Physica status solidi (A) : applications and materials N2 - The light-addressable potentiometric sensor (LAPS) is a semiconductor-based potentiometric sensor using a light probe with an ability of detecting the concentration of biochemical species in a spatially resolved manner. As an important biomedical sensor, research has been conducted to improve its performance, for instance, to realize high-speed measurement. In this work, the idea of facilitating the device-level simulation, instead of using an equivalent-circuit model, is presented for detailed analysis and optimization of the performance of the LAPS. Both carrier distribution and photocurrent response have been simulated to provide new insight into both amplitude-mode and phase-mode operations of the LAPS. Various device parameters can be examined to effectively design and optimize the LAPS structures and setups for enhanced performance. Y1 - 2014 U6 - http://dx.doi.org/10.1002/pssa.201330354 SN - 0031-8965 VL - 211 IS - 6 SP - 1467 EP - 1472 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Takenaga, Shoko A1 - Biselli, Manfred A1 - Schnitzler, Thomas A1 - Öhlschläger, Peter A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Toward multi-analyte bioarray sensors: LAPS-based on-chip determination of a Michaelis–Menten-like kinetics for cell culturing JF - Physica status solidi A : Applications and materials science N2 - The metabolic activity of Chinese hamster ovary (CHO) cells was observed using a light-addressable potentiometric sensor (LAPS). The dependency toward different glucose concentrations (17–200 mM) follows a Michaelis–Menten kinetics trajectory with Kₘ = 32.8 mM, and the obtained Kₘ value in this experiment was compared with that found in literature. In addition, the pH shift induced by glucose metabolism of tumor cells transfected with the HPV-16 genome (C3 cells) was successfully observed. These results indicate the possibility to determine the tumor cells metabolism with a LAPS-based measurement device. Y1 - 2014 U6 - http://dx.doi.org/10.1002/pssa.201330464 SN - 1521-396X (E); 1862-6319 (E-Journal); 0031-8965 (Print); 1862-6300 (Print) VL - 211 IS - 6 SP - 1410 EP - 1415 PB - Wiley-VCH CY - Weinheim ER -