TY - JOUR A1 - Jildeh, Zaid B. A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Vahidpour, Farnoosh A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - Development of a package-sterilization process for aseptic filling machines: A numerical approach and validation for surface treatment with hydrogen peroxide JF - Sensor and Actuators A: Physical N2 - Within the present work a sterilization process by a heated gas mixture that contains hydrogen peroxide (H₂O₂) is validated by experiments and numerical modeling techniques. The operational parameters that affect the sterilization efficacy are described alongside the two modes of sterilization: gaseous and condensed H₂O₂. Measurements with a previously developed H₂O₂ gas sensor are carried out to validate the applied H₂O₂ gas concentration during sterilization. We performed microbiological tests at different H₂O₂ gas concentrations by applying an end-point method to carrier strips, which contain different inoculation loads of Geobacillus stearothermophilus spores. The analysis of the sterilization process of a pharmaceutical glass vial is performed by numerical modeling. The numerical model combines heat- and advection-diffusion mass transfer with vapor–pressure equations to predict the location of condensate formation and the concentration of H₂O₂ at the packaging surfaces by changing the gas temperature. For a sterilization process of 0.7 s, a H₂O₂ gas concentration above 4% v/v is required to reach a log-count reduction above six. The numerical results showed the location of H₂O₂ condensate formation, which decreases with increasing sterilant-gas temperature. The model can be transferred to different gas nozzle- and packaging geometries to assure the absence of H₂O₂ residues. Y1 - 2020 U6 - https://doi.org/10.1016/j.sna.2019.111691 SN - 0924-4247 VL - 303 IS - 111691 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Dantism, Shahriar A1 - Takenaga, Shoko A1 - Wagner, Torsten A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Differential imaging of the metabolism of bacteria and eukaryotic cells based on light-addressable potentiometric sensors JF - Electrochimica Acta N2 - A light-addressable potentiometric sensor (LAPS) is a field-effect-based potentiometric sensor with an electrolyte/insulator/semiconductor (EIS) structure, which is able to monitor analyte concentrations of (bio-)chemical species in aqueous solutions in a spatially resolved way. Therefore, it is also an appropriate tool to record 2D-chemical images of concentration variations on the sensor surface. In the present work, two differential, LAPS-based measurement principles are introduced to determine the metabolic activity of Escherichia coli (E. coli) K12 and Chinese hamster ovary (CHO) cells as test microorganisms. Hereby, we focus on i) the determination of the extracellular acidification rate (ΔpH/min) after adding glucose solutions to the cell suspensions; and ii) recording the amplitude increase of the photocurrent (Iph) related to the produced acids from E. coli K12 bacteria and CHO cells on the sensor surface by 2D-chemical imaging. For this purpose, 3D-printed multi-chamber structures were developed and mounted on the planar sensor-chip surface to define four independent compartments, enabling differential measurements with varying cell concentrations. The differential concept allows eliminating unwanted drift effects and, with the four-chamber structures, measurements on the different cell concentrations were performed simultaneously, thus reducing also the overall measuring time. Y1 - 2017 U6 - https://doi.org/10.1016/j.electacta.2017.05.196 SN - 0013-4686 VL - 246 SP - 234 EP - 241 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Kremers, Alexander A1 - Wagner, Torsten A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - FEM-based modeling of a calorimetric gas sensor for hydrogen peroxide monitoring JF - physica status solidi a : applications and materials sciences N2 - A physically coupled finite element method (FEM) model is developed to study the response behavior of a calorimetric gas sensor. The modeled sensor serves as a monitoring device of the concentration of gaseous hydrogen peroxide (H2 O2) in a high temperature mixture stream in aseptic sterilization processes. The principle of operation of a calorimetric H2 O2 sensor is analyzed and the results of the numerical model have been validated by using previously published sensor experiments. The deviation in the results between the FEM model and experimental data are presented and discussed. Y1 - 2017 U6 - https://doi.org/10.1002/pssa.201600912 SN - 1862-6319 IS - Early View PB - Wiley-VCH CY - Weinheim ER - TY - CHAP A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Nanomaterial-Modified Capacitive Field-Effect Biosensors T2 - Springer Series on Chemical Sensors and Biosensors (Methods and Applications) N2 - The coupling of charged molecules, nanoparticles, and more generally, inorganic/organic nanohybrids with semiconductor field-effect devices based on an electrolyte–insulator–semiconductor (EIS) system represents a very promising strategy for the active tuning of electrochemical properties of these devices and, thus, opening new opportunities for label-free biosensing by the intrinsic charge of molecules. The simplest field-effect sensor is a capacitive EIS sensor, which represents a (bio-)chemically sensitive capacitor. In this chapter, selected examples of recent developments in the field of label-free biosensing using nanomaterial-modified capacitive EIS sensors are summarized. In the first part, we present applications of EIS sensors modified with negatively charged gold nanoparticles for the label-free electrostatic detection of positively charged small proteins and macromolecules, for monitoring the layer-by-layer formation of oppositely charged polyelectrolyte (PE) multilayers as well as for the development of an enzyme-based biomolecular logic gate. In the second part, examples of a label-free detection by means of EIS sensors modified with a positively charged weak PE layer are demonstrated. These include electrical detection of on-chip and in-solution hybridized DNA (deoxyribonucleic acid) as well as an EIS sensor with pH-responsive weak PE/enzyme multilayers for enhanced field-effect biosensing. KW - Biomolecular logic gate KW - DNA KW - Enzyme biosensor KW - Field-effect sensor KW - Gold nanoparticle Y1 - 2017 U6 - https://doi.org/10.1007/5346_2017_2 SP - 1 EP - 25 PB - Springer CY - Berlin, Heidelberg ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Hayashi, Kosuke A1 - Sakamoto, Azuma A1 - Werner, Frederik A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - A high-Q resonance-mode measurement of EIS capacitive sensor by elimination of series resistance JF - Sensor and Actuators B: Chemical N2 - An EIS capacitive sensor is a semiconductor-based potentiometric sensor, which is sensitive to the ion concentration or pH value of the solution in contact with the sensing surface. To detect a small change in the ion concentration or pH, a small capacitance change must be detected. Recently, a resonance-mode measurement was proposed, in which an inductor was connected to the EIS capacitive sensor and the resonant frequency was correlated with the pH value. In this study, the Q factor of the resonant circuit was enhanced by canceling the internal resistance of the reference electrode and the internal resistance of the inductor coil with the help of a bypass capacitor and a negative impedance converter, respectively. 1% variation of the signal in the developed system corresponded to a pH change of 3.93 mpH, which was about 1/12 of the conventional method, suggesting a better performance in detection of a small pH change. KW - Negative impedance convertor KW - Resonance-mode measurement KW - Chemical sensor KW - EIS capacitive sensor Y1 - 2017 U6 - https://doi.org/10.1016/j.snb.2017.03.002 SN - 0925-4005 VL - 248 SP - 1006 EP - 1010 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Werner, Frederik A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Lateral resolution enhancement of pulse-driven light-addressable potentiometric sensor JF - Sensor and Actuators B: Chemical N2 - To study chemical and biological processes, spatially resolved determination of the concentrations of one or more analyte species is of distinct interest. With a light-addressable potentiometric sensor (LAPS), chemical images can be created, which visualize the concentration distribution above the sensor plate. One important challenge is to achieve a good lateral resolution in order to detect events that take place in a small and limited region. LAPS utilizes a focused light spot to address the measurement region. By moving this light spot along the semiconductor sensor plate, the concentration distribution can be observed. In this study, we show that utilizing a pulse as light excitation instead of a traditionally used continuously modulated light excitation, the lateral resolution can be improved by a factor of 6 or more. KW - Chemical images KW - LAPS KW - Light-addressable potentiometric sensor Y1 - 2017 U6 - https://doi.org/10.1016/j.snb.2017.02.057 SN - 0925-4005 VL - 248 SP - 961 EP - 965 PB - Elsevier CY - Amsterdam 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 - https://doi.org/10.1021/acsami.7b08095 SN - 1944-8252 VL - 9 IS - 36 SP - 31054 EP - 31066 PB - ACS CY - Washington ER - TY - CHAP A1 - Jablonski, Melanie A1 - Koch, Claudia A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Wege, Christina A1 - Schöning, Michael Josef T1 - Field-Effect Biosensors Modified with Tobacco Mosaic Virus Nanotubes as Enzyme Nanocarrier T2 - MDPI Proceeding Y1 - 2017 U6 - https://doi.org/10.3390/proceedings1040505 N1 - Eurosensors 2017 Conference, Paris, France, 3–6 September 2017 VL - 1 IS - 4 ER - TY - CHAP A1 - Miyamoto, Ko-ichiro A1 - Suto, Takeyuki A1 - Werner, Frederik A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Restraining the Diffusion of Photocarriers to Improve the Spatial Resolution of the Chemical Imaging Sensor T2 - MDPI Proceedings Y1 - 2017 U6 - https://doi.org/10.3390/proceedings1040477 N1 - Eurosensors 2017 Conference, Paris, France, 3–6 September 2017 VL - 1 IS - 4 ER - TY - JOUR A1 - Muschallik, Lukas A1 - Molinnus, Denise A1 - Bongaerts, Johannes A1 - Pohl, Martina A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Siegert, Petra A1 - Selmer, Thorsten T1 - (R,R)-Butane-2,3-diol Dehydrogenase from Bacillus clausii DSM 8716T: Cloning and Expression of the bdhA-Gene, and Initial Characterization of Enzyme JF - Journal of Biotechnology N2 - The gene encoding a putative (R,R)-butane-2,3-diol dehydrogenase (bdhA) from Bacillus clausii DSM 8716T was isolated, sequenced and expressed in Escherichia coli. The amino acid sequence of the encoded protein is only distantly related to previously studied enzymes (identity 33–43%) and exhibited some uncharted peculiarities. An N-terminally StrepII-tagged enzyme variant was purified and initially characterized. The isolated enzyme catalyzed the (R)-specific oxidation of (R,R)- and meso-butane-2,3-diol to (R)- and (S)-acetoin with specific activities of 12 U/mg and 23 U/mg, respectively. Likewise, racemic acetoin was reduced with a specific activity of up to 115 U/mg yielding a mixture of (R,R)- and meso-butane-2,3-diol, while the enzyme reduced butane-2,3-dione (Vmax 74 U/mg) solely to (R,R)-butane-2,3-diol via (R)-acetoin. For these reactions only activity with the co-substrates NADH/NAD+ was observed. The enzyme accepted a selection of vicinal diketones, α-hydroxy ketones and vicinal diols as alternative substrates. Although the physiological function of the enzyme in B. clausii remains elusive, the data presented herein clearly demonstrates that the encoded enzyme is a genuine (R,R)-butane-2,3-diol dehydrogenase with potential for applications in biocatalysis and sensor development. Y1 - 2017 U6 - https://doi.org/10.1016/j.jbiotec.2017.07.020 SN - 0168-1656 VL - 258 SP - 41 EP - 50 PB - Elsevier CY - Amsterdam ER -