TY - JOUR A1 - Bäcker, Matthias A1 - Rakowski, D. A1 - Poghossian, Arshak A1 - Biselli, Manfred A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Chip-based amperometric enzyme sensor system for monitoring of bioprocesses by flow-injection analysis JF - Journal of Biotechnology N2 - A microfluidic chip integrating amperometric enzyme sensors for the detection of glucose, glutamate and glutamine in cell-culture fermentation processes has been developed. The enzymes glucose oxidase, glutamate oxidase and glutaminase were immobilized by means of cross-linking with glutaraldehyde on platinum thin-film electrodes integrated within a microfluidic channel. The biosensor chip was coupled to a flow-injection analysis system for electrochemical characterization of the sensors. The sensors have been characterized in terms of sensitivity, linear working range and detection limit. The sensitivity evaluated from the respective peak areas was 1.47, 3.68 and 0.28 μAs/mM for the glucose, glutamate and glutamine sensor, respectively. The calibration curves were linear up to a concentration of 20 mM glucose and glutamine and up to 10 mM for glutamate. The lower detection limit amounted to be 0.05 mM for the glucose and glutamate sensor, respectively, and 0.1 mM for the glutamine sensor. Experiments in cell-culture medium have demonstrated a good correlation between the glutamate, glutamine and glucose concentrations measured with the chip-based biosensors in a differential-mode and the commercially available instrumentation. The obtained results demonstrate the feasibility of the realized microfluidic biosensor chip for monitoring of bioprocesses. Y1 - 2013 U6 - https://doi.org/10.1016/j.jbiotec.2012.03.014 SN - 0168-1656 VL - 163 IS - 4 SP - 371 EP - 376 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Abouzar, Maryam H. A1 - Poghossian, Arshak A1 - Cherstvy, Andrey G. A1 - Pedraza, Angela M. A1 - Ingebrandt, Sven A1 - Schöning, Michael Josef T1 - Label-free electrical detection of DNA by means of field-effect nanoplate capacitors: Experiments and modeling JF - Physica Status Solidi (a) N2 - Label-free electrical detection of consecutive deoxyribonucleic acid (DNA) hybridization/denaturation by means of an array of individually addressable field-effect-based nanoplate silicon-on-insulator (SOI) capacitors modified with gold nanoparticles (Au-NP) is investigated. The proposed device detects charge changes on Au-NP/DNA hybrids induced by the hybridization or denaturation event. DNA hybridization was performed in a high ionic-strength solution to provide a high hybridization efficiency. On the other hand, to reduce the screening of the DNA charge by counter ions and to achieve a high sensitivity, the sensor signal induced by the hybridization and denaturation events was measured in a low ionic-strength solution. High sensor signals of about 120, 90, and 80 mV were registered after the DNA hybridization, denaturation, and re-hybridization events, respectively. Fluorescence microscopy has been applied as reference method to verify the DNA immobilization, hybridization, and denaturation processes. An electrostatic charge-plane model for potential changes at the gate surface of a nanoplate field-effect sensor induced by the DNA hybridization has been developed taking into account both the Debye length and the distance of the DNA charge from the gate surface. Y1 - 2012 U6 - https://doi.org/10.1002/pssa.201100710 SN - 1862-6319 VL - 209 SP - 925 EP - 934 PB - Wiley-VCH CY - Weinheim ER - TY - CHAP A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-Ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef ED - Yamaguchi, Takami T1 - Miniaturized and high-speed chemical imaging systems T2 - Nano-Biomedical Engineering 2012. Proceedings of the Tohoku University Global Centre of Excellence Programme, Sakura Hall, Tohoku University, Sendai Japan, 5 – 6 March 2012 Y1 - 2012 U6 - https://doi.org/10.1142/9781848169067_0045 SP - 386 EP - 395 PB - World Scientific CY - Singapur ER - TY - JOUR A1 - Spiess, Elmar A1 - Wilfried, Reichardt A1 - Alvarez, Gerardo A1 - Gottrup, Marcus A1 - Öhlschläger, Peter T1 - An Artificial PAP Gene Breaks Self-tolerance and Promotes Tumor Regression in the TRAMP Model for Prostate Carcinoma JF - Molecular Therapy Y1 - 2011 SN - 1525-0016 VL - 20 IS - 3 SP - 555 EP - 564 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Grinsven, Bart van A1 - Bon, Natalie vanden A1 - Strauven, Hannelore A1 - Grieten, Lars A1 - Murib, Mohammed A1 - Jiménez Monroy, Kathia L. A1 - Janssens, Stoffel D. A1 - Haenen, Ken A1 - Schöning, Michael Josef A1 - Vermeeren, Veronique A1 - Ameloot, Marcel A1 - Michiels, Luc A1 - Thoelen, Ronald A1 - Ceuninck, Ward de A1 - Wagner, Patrick T1 - Heat-Transfer Resistance at Solid-Liquid Interfaces: A Tool for The Detection of Single Nucleotide Polymorphisms in DNA. JF - ACS Nano N2 - In this article, we report on the heat-transfer resistance at interfaces as a novel, denaturation-based method to detect single-nucleotide polymorphisms in DNA. We observed that a molecular brush of double-stranded DNA grafted onto synthetic diamond surfaces does not notably affect the heat-transfer resistance at the solid-to-liquid interface. In contrast to this, molecular brushes of single-stranded DNA cause, surprisingly, a substantially higher heat-transfer resistance and behave like a thermally insulating layer. This effect can be utilized to identify ds-DNA melting temperatures via the switching from low- to high heat-transfer resistance. The melting temperatures identified with this method for different DNA duplexes (29 base pairs without and with built-in mutations) correlate nicely with data calculated by modeling. The method is fast, label-free (without the need for fluorescent or radioactive markers), allows for repetitive measurements, and can also be extended toward array formats. Reference measurements by confocal fluorescence microscopy and impedance spectroscopy confirm that the switching of heat-transfer resistance upon denaturation is indeed related to the thermal on-chip denaturation of DNA. Y1 - 2012 U6 - https://doi.org/10.1021/nn300147e SN - 1936-086X VL - 6 IS - 3 SP - 2712 EP - 2721 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Arida, Hassan A. A1 - Al-haddad, Ameera A1 - Schöning, Michael Josef T1 - New Solid-State Organic Membrane Based Lead-Selective Micro-Electrode JF - International Journal of Electrochemical Science. 6 (2011), H. 9 Y1 - 2011 SN - 1452-3981 SP - 3858 EP - 3867 ER - TY - JOUR A1 - Bäcker, Matthias A1 - Raue, Markus A1 - Schusser, Sebastian A1 - Jeitner, C. A1 - Breuer, L. A1 - Wagner, P. A1 - Poghossian, Arshak A1 - Förster, Arnold A1 - Mang, Thomas A1 - Schöning, Michael Josef T1 - Microfluidic chip with integrated microvalves based on temperature- and pH-responsive hydrogel thin films JF - Physica Status Solidi (a) N2 - Two types of microvalves based on temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) and pH-responsive poly(sodium acrylate) (PSA) hydrogel films have been developed and tested. The PNIPAAm and PSA hydrogel films were prepared by means of in situ photopolymerization directly inside the fluidic channel of a microfluidic chip fabricated by combining Si and SU-8 technologies. The swelling/shrinking properties and height changes of the PNIPAAm and PSA films inside the fluidic channel were studied at temperatures of deionized water from 14 to 36 °C and different pH values (pH 3–12) of Titrisol buffer, respectively. Additionally, in separate experiments, the lower critical solution temperature (LCST) of the PNIPAAm hydrogel was investigated by means of a differential scanning calorimetry (DSC) and a surface plasmon resonance (SPR) method. Mass-flow measurements have shown the feasibility of the prepared hydrogel films to work as an on-chip integrated temperature- or pH-responsive microvalve capable to switch the flow channel on/off. Y1 - 2012 U6 - https://doi.org/10.1002/pssa.201100763 SN - 1862-6319 VL - 209 IS - 5 SP - 839 EP - 845 PB - Wiley-VCH CY - Weinheim ER - TY - CHAP A1 - Schusser, Sebastian A1 - Vaeßen, Christiane A1 - Schöning, Michael Josef T1 - 5. Graduiertentagung der FH Aachen 15. November 2012 T1 - 5th Graduate Symposium FH Aachen - University of Applied Sciences November 15th, 2012 N2 - Tagungsband der 5. Graduiertentagung der FH Aachen am 15. November 2012 N2 - Proceedings from the 5th Graduate Symposium, FH Aachen, Germany, November 15th, 2012 T3 - Graduiertentagung / FH Aachen - 5 KW - Graduiertentagung Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:a96-opus-50425 ER - TY - JOUR A1 - Werner, Frederik A1 - Takenaga, Shoko A1 - Taki, Hidenori A1 - Sawada, Kazuaki A1 - Schöning, Michael Josef T1 - Comparison of label-free ACh-imaging sensors based on CCD and LAPS JF - Sensors and Actuators B: Chemical (2012) N2 - Semiconductor-based chemical imaging sensors, like the light-addressable potentiometric sensor (LAPS) or the pH-imaging sensor based on a charge-coupled device (CCD), are becoming a powerful tool for label-free imaging of biological phenomena. We have proposed a polyion-based enzymatic membrane to develop an acetylcholine (ACh) imaging sensor for neural cell-activity observations. In this study, a CCD-type ACh-imaging sensor and a LAPS-type ACh-imaging sensor were fabricated and the prospect of both sensors was clarified by making a comparison of their basic characteristics. Y1 - 2013 SN - 0925-4005 VL - 177 SP - 745 EP - 752 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Suco, Henri-Pierre A1 - Rysstad, Gunnar A1 - Schöning, Michael Josef T1 - Monitoring the microbicidal effectiveness of gaseous hydrogen peroxide in sterilisation processes by means of a calorimetric gas sensor JF - Food control N2 - In the present work, a novel method for monitoring sterilisation processes with gaseous H2O2 in combination with heat activation by means of a specially designed calorimetric gas sensor was evaluated. Therefore, the sterilisation process was extensively studied by using test specimens inoculated with Bacillus atrophaeus spores in order to identify the most influencing process factors on its microbicidal effectiveness. Besides the contact time of the test specimens with gaseous H2O2 varied between 0.2 and 0.5 s, the present H2O2 concentration in a range from 0 to 8% v/v (volume percent) had a strong influence on the microbicidal effectiveness, whereas the change of the vaporiser temperature, gas flow and humidity were almost negligible. Furthermore, a calorimetric H2O2 gas sensor was characterised in the sterilisation process with gaseous H2O2 in a wide range of parameter settings, wherein the measurement signal has shown a linear response against the H2O2 concentration with a sensitivity of 4.75 °C/(% v/v). In a final step, a correlation model by matching the measurement signal of the gas sensor with the microbial inactivation kinetics was established that demonstrates its suitability as an efficient method for validating the microbicidal effectiveness of sterilisation processes with gaseous H2O2. KW - hydrogen peroxide KW - sterilisation KW - Bacillus atrophaeus KW - calorimetric gas sensor Y1 - 2012 U6 - https://doi.org/10.1016/j.foodcont.2012.11.048 SN - 0956-7135 VL - 31 IS - 2 SP - 530 EP - 538 PB - Elsevier CY - Amsterdam ER -