TY - JOUR A1 - Beging, Stefan A1 - Mlynek, Daniela A1 - Hataihimakul, Sudkanung A1 - Poghossian, Arshak A1 - Baldsiefen, Gerhard A1 - Busch, Heinz A1 - Laube, Norbert A1 - Kleinen, Lisa A1 - Schöning, Michael Josef T1 - Field-effect calcium sensor for the determination of the risk of urinary stone formation JF - Sensors and Actuators B: Chemical. 144 (2010), H. 2 Y1 - 2010 N1 - 22nd International Conference on Eurosensors - Dresden, Germany, 7-10 September 2008 ; Eurosensors ; (22, 2008, Dresden) SP - 374 EP - 379 ER - TY - JOUR A1 - Buniatyan, V. A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Aroutiounian, V. M. A1 - Schöning, Michael Josef T1 - BaxSr1-x TiO3/pc-Si heterojunction JF - Armenian journal of physics Y1 - 2013 SN - 1829-1171 VL - 6 IS - 4 SP - 177 EP - 187 PB - National Academy of Sciences of Armenia CY - Yerevan ER - TY - JOUR A1 - Yoshinobu, T. A1 - Ecken, H. A1 - Poghossian, Arshak A1 - Lüth, H. A1 - Iwasaki, H. A1 - Schöning, Michael Josef T1 - Alternative sensor materials for light-addressable potentiometric sensors JF - Sensors and Actuators B. 76 (2001), H. 1-3 Y1 - 2001 SN - 0925-4005 SP - 388 EP - 392 ER - TY - JOUR A1 - Poghossian, Arshak A1 - Abouzar, Maryam H. A1 - Sakkari, M. A1 - Kassab, T. A1 - Han, Y. A1 - Ingebrandt, S. A1 - Offenhäusser, A. A1 - Schöning, Michael Josef T1 - Field-effect sensors for monitoring the layer-by-layer adsorption of charged macromolecules JF - Sensors and Actuators B: Chemical. 118 (2006), H. 1-2 Y1 - 2006 SN - 0925-4005 N1 - Eurosensors XIX - Eurosensors XIX - The 19th European Conference on Solid-State Transducers SP - 163 EP - 170 ER - TY - JOUR A1 - Krämer, Melina A1 - Pita, Marcos A1 - Zhou, Jian A1 - Ornatska, Maryna A1 - Poghossian, Arshak A1 - Schöning, Michael Josef A1 - Katz, Evgeny T1 - Coupling of Biocomputing Systems with Electronic Chips: Electronic Interface for Transduction of Biochemical Information JF - Journal of Physical Chemistry C: Nanomaterials and Interfaces. 113 (2009), H. 6 Y1 - 2009 SN - 1932-7455 SP - 2573 EP - 2579 PB - American Cemical Society CY - Washington, DC ER - TY - JOUR A1 - Wu, Chunsheng A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Werner, Frederik A1 - Bäcker, Matthias A1 - Schöning, Michael Josef T1 - Label-free electrical detection of DNA with a multi-spot LAPS: First step towards light-addressable DNA chips JF - Physica status solidi A : Applications and materials science N2 - A multi-spot (4 × 4 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al–p-Si–SiO2 structure has been applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. Single-stranded probe ssDNA molecules (20 bases) were covalently immobilized onto the silanized SiO2 gate surface. The unspecific adsorption of mismatch ssDNA on the MLAPS gate surface was blocked by bovine serum albumin molecules. To reduce the screening effect and to achieve a high sensor signal, the measurements were performed in a low ionic-strength solution. The photocurrent–voltage (I–V) curves were simultaneously recorded on all 16 spots after each surface functionalization step. Large shifts of I–V curves of 25 mV were registered after the DNA immobilization and hybridization event. In contrast, a small potential shift (∼5 mV) was observed in case of mismatch ssDNA, revealing good specificity of the sensor. The obtained results demonstrate the potential of the MLAPS as promising transducer platform for the multi-spot label-free electrical detection of DNA molecules by their intrinsic molecular charge. Y1 - 2014 U6 - https://doi.org/10.1002/pssa.201330442 SN - 1521-396X (E-Journal); 1862-6319 (E-Journal); 0031-8965 (Print); 1862-6300 (Print) VL - 211 IS - 6 SP - 1423 EP - 1428 PB - Wiley-VCH CY - Weinheim ER - TY - CHAP A1 - Näther, Niko A1 - Poghossian, Arshak A1 - Platen, J. A1 - Yoshinobu, T. A1 - Koudelka-Hep, M. A1 - Schöning, Michael Josef T1 - Multi-parameter sensing of both physical and (bio-)chemical quantities using the same transducer principle T2 - Biochemical sensing utilisation of micro- and nanotechnologies : Warsaw, [23rd - 26th] November 2005 / ed. by M. Mascini ... Y1 - 2006 SP - 172 EP - 181 CY - Warsaw ER - TY - JOUR A1 - Poghossian, Arshak A1 - Jablonski, Melanie A1 - Molinnus, Denise A1 - Wege, Christina A1 - Schöning, Michael Josef T1 - Field-Effect Sensors for Virus Detection: From Ebola to SARS-CoV-2 and Plant Viral Enhancers JF - Frontiers in Plant Science N2 - Coronavirus disease 2019 (COVID-19) is a novel human infectious disease provoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, no specific vaccines or drugs against COVID-19 are available. Therefore, early diagnosis and treatment are essential in order to slow the virus spread and to contain the disease outbreak. Hence, new diagnostic tests and devices for virus detection in clinical samples that are faster, more accurate and reliable, easier and cost-efficient than existing ones are needed. Due to the small sizes, fast response time, label-free operation without the need for expensive and time-consuming labeling steps, the possibility of real-time and multiplexed measurements, robustness and portability (point-of-care and on-site testing), biosensors based on semiconductor field-effect devices (FEDs) are one of the most attractive platforms for an electrical detection of charged biomolecules and bioparticles by their intrinsic charge. In this review, recent advances and key developments in the field of label-free detection of viruses (including plant viruses) with various types of FEDs are presented. In recent years, however, certain plant viruses have also attracted additional interest for biosensor layouts: Their repetitive protein subunits arranged at nanometric spacing can be employed for coupling functional molecules. If used as adapters on sensor chip surfaces, they allow an efficient immobilization of analyte-specific recognition and detector elements such as antibodies and enzymes at highest surface densities. The display on plant viral bionanoparticles may also lead to long-time stabilization of sensor molecules upon repeated uses and has the potential to increase sensor performance substantially, compared to conventional layouts. This has been demonstrated in different proof-of-concept biosensor devices. Therefore, richly available plant viral particles, non-pathogenic for animals or humans, might gain novel importance if applied in receptor layers of FEDs. These perspectives are explained and discussed with regard to future detection strategies for COVID-19 and related viral diseases. Y1 - 2020 U6 - https://doi.org/10.3389/fpls.2020.598103 VL - 11 IS - Article 598103 SP - 1 EP - 14 PB - Frontiers CY - Lausanne ER - TY - JOUR A1 - Schusser, Sebastian A1 - Leinhos, Marcel A1 - Bäcker, Matthias A1 - Poghossian, Arshak A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Impedance spectroscopy: A tool for real-time in situ monitoring of the degradation of biopolymers JF - Physica Status Solidi (A) N2 - Investigation of the degradation kinetics of biodegradable polymers is essential for the development of implantable biomedical devices with predicted biodegradability. In this work, an impedimetric sensor has been applied for real-time and in situ monitoring of degradation processes of biopolymers. The sensor consists of two platinum thin-film electrodes covered by a polymer film to be studied. The benchmark biomedical polymer poly(D,L-lactic acid) (PDLLA) was used as a model system. PDLLA films were deposited on the sensor structure from a polymer solution by using the spin-coating method. The degradation kinetics of PDLLA films have been studied in alkaline solutions of pH 9 and 12 by means of an impedance spectroscopy (IS) method. Any changes in a polymer capacitance/resistance induced by water uptake and/or polymer degradation will modulate the global impedance of the polymer-covered sensor that can be used as an indicator of the polymer degradation. The degradation rate can be evaluated from the time-dependent impedance spectra. As expected, a faster degradation has been observed for PDLLA films exposed to pH 12 solution. Y1 - 2013 U6 - https://doi.org/10.1002/pssa.201200941 SN - 1521-396X ; 0031-8965 VL - 210 IS - 5 SP - 905 EP - 910 PB - Wiley CY - Weinheim ER - TY - BOOK A1 - Schöning, Michael Josef A1 - Poghossian, Arshak T1 - Label-free biosensing: advanced materials, devices and applications Y1 - 2018 SN - 978-3-319-75219-8 PB - Springer CY - Cham ER - TY - JOUR A1 - Janus, Kevin Alexander A1 - Achtsnicht, Stefan A1 - Drinic, Aleksander A1 - Kopp, Alexander A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Transient magnesium-based thin-film temperature sensor on a flexible, bioabsorbable substrate for future medical applications JF - Applied Research N2 - In this work, the bioabsorbable materials, namely fibroin, polylactide acid (PLA), magnesium and magnesium oxide are investigated for their application as transient, resistive temperature detectors (RTD). For this purpose, a thin-film magnesium-based meander-like electrode is deposited onto a flexible, bioabsorbable substrate (fibroin or PLA) and encapsulated (passivated) by additional magnesium oxide layers on top and below the magnesium-based electrode. The morphology of different layered RTDs is analyzed by scanning electron microscopy. The sensor performance and lifetime of the RTD is characterized both under ambient atmospheric conditions between 30°C and 43°C, and wet tissue-like conditions with a constant temperature regime of 37°C. The latter triggers the degradation process of the magnesium-based layers. The 3-layers RTDs on a PLA substrate could achieve a lifetime of 8.5 h. These sensors also show the best sensor performance under ambient atmospheric conditions with a mean sensitivity of 0.48 Ω/°C ± 0.01 Ω/°C. KW - Silk fibroin KW - Polylactide acid KW - Bioabsorbable KW - Resistive temperature detector Y1 - 2023 U6 - https://doi.org/10.1002/appl.202300102 SN - 2702-4288 (Print) N1 - Corresponding author: Michael Josef Schöning IS - Accepted manuscript PB - Wiley-VCH ER - TY - JOUR A1 - Janus, Kevin Alexander A1 - Achtsnicht, Stefan A1 - Tempel, Laura A1 - Drinic, Aleksaner A1 - Kopp, Alexander A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Influence of fibroin membrane composition and curing parameters on the performance of a biodegradable enzymatic biosensor manufactured from Silicon-Free Carbon JF - Physica status solidi : pss. A, Applications and materials science N2 - Herein, fibroin, polylactide (PLA), and carbon are investigated for their suitability as biocompatible and biodegradable materials for amperometric biosensors. For this purpose, screen-printed carbon electrodes on the biodegradable substrates fibroin and PLA are modified with a glucose oxidase membrane and then encapsulated with the biocompatible material Ecoflex. The influence of different curing parameters of the carbon electrodes on the resulting biosensor characteristics is studied. The morphology of the electrodes is investigated by scanning electron microscopy, and the biosensor performance is examined by amperometric measurements of glucose (0.5–10 mM) in phosphate buffer solution, pH 7.4, at an applied potential of 1.2 V versus a Ag/AgCl reference electrode. Instead of Ecoflex, fibroin, PLA, and wound adhesive are tested as alternative encapsulation compounds: a series of swelling tests with different fibroin compositions, PLA, and Ecoflex has been performed before characterizing the most promising candidates by chronoamperometry. Therefore, the carbon electrodes are completely covered with the particular encapsulation material. Chronoamperometric measurements with H2O2 concentrations between 0.5 and 10 mM enable studying the leakage current behavior. KW - amperometric biosensors KW - biocompatible KW - biodegradabl KW - encapsulation materials KW - fibroin Y1 - 2023 U6 - https://doi.org/10.1002/pssa.202300081 SN - 1862-6300 (Print) SN - 1862-6319 (Online) N1 - Corresponding author: Michael J. Schöning VL - 220 IS - 22 PB - Wiley-VCH CY - Weinheim ER - TY - THES A1 - Achtsnicht, Stefan T1 - Multiplex-Magnetdetektion von superparamagnetischen Beads zur Identifizierung von Trinkwasserkontaminationen N2 - Die qualitative und quantitative Detektion von Zielsubstanzen innerhalb einer wässrigen Probe ist für viele Fragestellungen von Interesse, etwa bei der Detektion von Kontaminationen in Trinkwasser in Krisensituationen. Hierbei ist es nicht nur wichtig, dass Pathogene möglichst sensitiv detektiert werden können, sondern auch, dass die Analyse schnell erfolgt, um Betroffenen im Katastrophenfall zügig sicheres Trinkwasser zu Verfügung stellen zu können. Da bei einem solchen Szenario nicht von einer in der Nähe befindlichen funktionierenden Laborinfrastruktur ausgegangen werden kann, ist es wichtig, dass die Messung direkt vor Ort erfolgen kann. Im Rahmen dieser Arbeit wurde untersucht, ob eine derartige Schnellanalytik mithilfe von superparamagnetischen Beads (MBs) und der magnetischen Frequenzmischtechnik möglich ist. Dabei werden die MBs mit Hilfe von primären Antikörpern an die Zielsubstanz gebunden und mit sekundären Antikörpern an die Poren-Oberfläche eines Polyethylen-Filters fixiert (Sandwich-Immunoassay). So kann die Quantifizierung der Zielsubstanz auf eine magnetische Messung der immobilisierten MB-Marker zurückgeführt werden. Die magnetische Frequenzmischtechnik basiert auf der Anregung der Probe mit Magnetfeldern zweier verschiedener Frequenzen. Die durch die nichtlineare Magnetisierungsform der superparamagnetischen MBs entstehenden Mischfrequenzen werden typischerweise mithilfe einer zweistufigen Lock-in-Detektion analysiert (analoge Demodulation), die in einem Magnetreader als Handheldgerät realisiert wurde. Zusätzlich zu dieser Technik wurde das Prinzip der direkten Digitalisierung des gesamten Antwortsignals mit anschließender Fourier-Analyse der erzeugten Mischfrequenzen experimentell umgesetzt, um die Amplituden und Phasen mehrerer Mischfrequenzen simultan zu erfassen. Eine Möglichkeit zur Sensitivitätssteigerung ist die magnetische Aufkonzentration, indem vor der magnetischen Analyse eine Separation der MBs aus einem größeren Probenvolumen mittels magnetischem Feldgradienten durchgeführt wird. Zur Charakterisierung verschiedener kommerzieller MBs hinsichtlich ihrer magnetischen Separierbarkeit wurde ein Aufbau zur Messung ihrer magnetophoretischen Beweglichkeiten realisiert und ihre Geschwindigkeiten im Gradientenfeld mikroskopisch gemessen.Da eine Probe oftmals nicht nur auf eine einzige Zielsubstanz, sondern simultan auf mehrere verschiedene Pathogene hin untersucht werden soll, wurden verschiedene Ansätze entwickelt und getestet, die einen solchen multiparametrischen magnetischen Immunoassay ermöglichen. Einerseits wurde eine räumliche Separation der Bindungsbereiche für verschiedene Zielsubstanzen realisiert, die sequentiell ausgewertet werden können. Andererseits wurde die Unterscheidung von verschiedenen Zielsubstanzen anhand der Charakteristika der an sie gebundenen, verschieden funktionalisierten MB-Typen untersucht. Für eine solche Unterscheidung wurde zum einen die Anregefrequenz der magnetischen Frequenzmischtechnik während einer Messung variiert. Damit konnte gezeigt werden, dass sich verschiedene MB-Sorten anhand der Phase ihrer Frequenzmischsignale voneinander unterscheiden lassen. Weiterhin wurde gezeigt, dass sich der Signalverlauf einer binären Mischung zweier verschiedener MB-Typen als gradueller Übergang der Verläufe der beiden reinen MB-Lösungen ergibt. Eine weitere Analysemethode für einen multiparametrischen Immunoassay besteht darin, ein zusätzliches einstellbares statisches magnetisches Offsetfeld zu verwenden. Hierfür wurden mehrere Aufbauten auf Basis von Permanent- und Elektromagneten simuliert, konstruiert und charakterisiert. Mithilfe von Simulationen konnte gezeigt werden, dass eine auf diesem Verfahren beruhende Unterscheidung für MBs mit unterschiedlichen magnetischen Partikelmomenten möglich ist. Als direkte Anwendung des hier entwickelten Magnetreaders in Zusammenspiel mit der digitalen Demodulation wurde ein magnetischer Assay gegen die B-Untereinheit des Choleratoxins in Trinkwasser mit einem niedrigen Detektionslimit von 0,2 ng/ml demonstriert. N2 - The qualitative and quantitative detection of target substances in an aqueous sample is of interest for many questions, for example in the detection of contaminations in drinking water in crisis situations. It is not only important that pathogens can be detected with highest possible sensitivity, but also that the analysis is carried out quickly so that safe drinking water can be provided in the event of a disaster. During such a scenario one cannot rely on a functioning laboratory infrastructure nearby. Therefore it is important that the measurement can be carried out directly on site. Within the scope of this work, it was investigated whether such a quick analysis can be performed using superparamagnetic beads (MBs) and the magnetic frequency mixing technique. The MBs are bound to the target substance with the aid of primary antibodies and fixed to the pore surfaces of a polyethylene filter with secondary antibodies (sandwich immunoassay). The quantification of the target substance can thus be traced back to a magnetic measurement of the immobilized MB markers. The magnetic frequency mixing technique is based on the excitation of the sample with magnetic fields of two different frequencies. The mixing frequencies generated due to the non-linear shape of the magnetization of the superparamagnetic MBs are typically analyzed using a two-stage Lock-in detection (analog demodulation), which was implemented in a magnetic reader as a handheld device. In addition to this technique, the principle of direct digitization of the entire response signal with subsequent Fourier analysis of the generated mixing frequencies was experimentally implemented in order to simultaneously record the amplitudes and phases of several mixing frequencies. One possibility for increasing the sensitivity is magnetic concentration. In that case, the MBs are separated from a larger sample volume by means of a magnetic field gradient before the magnetic analysis. To characterize various commercial MBs with regard to their magnetic separability, a setup for measuring their magnetophoretic mobility was implemented and their velocities in the gradient field were measured with an optical microscope.Often, a sample has to be examined not only for a single target substance, but for several different pathogens simultaneously. Various approaches have been developed and tested which enable such a multiparametric magnetic immunoassay. On the one hand, a spatial separation of the binding areas for different target substances was realized, which can be evaluated sequentially. On the other hand, a distinction among different target substances based on the magnetic characteristics of their attached different MB types was examined. For this discrimination, the excitation frequency of the magnetic frequency mixing technology was varied during measurement. It is shown that different MB types can be distinguished from one another based on the phase of their frequency mixing signals. The signal curve of a binary mixture of two different MB types is obtained as a gradual transition of the curves of the two pure MB solutions. Another method of analysis for a multiparametric immunoassay is based on an additional adjustable static magnetic offset field. For this purpose, several setups based on permanent magnets and electromagnets were simulated, designed and characterized. The simulations show that a distinction based on this method is possible for MBs with different magnetic particle moments. As a direct application of the developed magnetic reader in conjunction with digital demodulation, a magnetic assay against the B subunit of cholera toxin in drinking water was demonstrated, and a low detection limit of 0.2 ng/ml was achieved. KW - Choleratoxin B KW - Trinkwassersicherheit KW - cholera toxin B KW - drinking water safety KW - magnetic frequency mixing technique Y1 - 2020 U6 - https://doi.org/10.18154/RWTH-2020-12052 N1 - Dissertation, RWTH Aachen University, 2020 ER - TY - JOUR A1 - Karschuck, Tobias A1 - Poghossian, Arshak A1 - Ser, Joey A1 - Tsokolakyan, Astghik A1 - Achtsnicht, Stefan A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Capacitive model of enzyme-modified field-effect biosensors: Impact of enzyme coverage JF - Sensors and Actuators B: Chemical N2 - Electrolyte-insulator-semiconductor capacitors (EISCAP) belong to field-effect sensors having an attractive transducer architecture for constructing various biochemical sensors. In this study, a capacitive model of enzyme-modified EISCAPs has been developed and the impact of the surface coverage of immobilized enzymes on its capacitance-voltage and constant-capacitance characteristics was studied theoretically and experimentally. The used multicell arrangement enables a multiplexed electrochemical characterization of up to sixteen EISCAPs. Different enzyme coverages have been achieved by means of parallel electrical connection of bare and enzyme-covered single EISCAPs in diverse combinations. As predicted by the model, with increasing the enzyme coverage, both the shift of capacitance-voltage curves and the amplitude of the constant-capacitance signal increase, resulting in an enhancement of analyte sensitivity of the EISCAP biosensor. In addition, the capability of the multicell arrangement with multi-enzyme covered EISCAPs for sequentially detecting multianalytes (penicillin and urea) utilizing the enzymes penicillinase and urease has been experimentally demonstrated and discussed. KW - Field-effect biosensor KW - Capacitive model KW - Enzyme coverage KW - Multianalyte detection KW - Penicillin Y1 - 2024 U6 - https://doi.org/10.1016/j.snb.2024.135530 SN - 0925-4005 (Print) SN - 1873-3077 (Online) N1 - Corresponding Author: Michael J. Schöning VL - 408 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Molinnus, Denise A1 - Janus, Kevin Alexander A1 - Fang, Anyelina C. A1 - Drinic, Aleksander A1 - Achtsnicht, Stefan A1 - Köpf, Marius A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Thick-film carbon electrode deposited onto a biodegradable fibroin substrate for biosensing applications JF - Physica status solidi (a) N2 - This study addresses a proof-of-concept experiment with a biocompatible screen-printed carbon electrode deposited onto a biocompatible and biodegradable substrate, which is made of fibroin, a protein derived from silk of the Bombyx mori silkworm. To demonstrate the sensor performance, the carbon electrode is functionalized as a glucose biosensor with the enzyme glucose oxidase and encapsulated with a silicone rubber to ensure biocompatibility of the contact wires. The carbon electrode is fabricated by means of thick-film technology including a curing step to solidify the carbon paste. The influence of the curing temperature and curing time on the electrode morphology is analyzed via scanning electron microscopy. The electrochemical characterization of the glucose biosensor is performed by amperometric/voltammetric measurements of different glucose concentrations in phosphate buffer. Herein, systematic studies at applied potentials from 500 to 1200 mV to the carbon working electrode (vs the Ag/AgCl reference electrode) allow to determine the optimal working potential. Additionally, the influence of the curing parameters on the glucose sensitivity is examined over a time period of up to 361 days. The sensor shows a negligible cross-sensitivity toward ascorbic acid, noradrenaline, and adrenaline. The developed biocompatible biosensor is highly promising for future in vivo and epidermal applications. KW - biocompatible materials KW - biodegradable electronic devices KW - biosensors KW - carbon electrodes KW - glucose Y1 - 2022 U6 - https://doi.org/10.1002/pssa.202200100 SN - 1862-6319 N1 - Corresponding author: Michael J. Schöning VL - 219 IS - 23 SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Özsoylu, Dua A1 - Kizildag, Sefa A1 - Schöning, Michael Josef A1 - Wagner, Torsten T1 - Differential chemical imaging of extracellular acidification within microfluidic channels using a plasma-functionalized light-addressable potentiometric sensor (LAPS) JF - Physics in Medicine N2 - Extracellular acidification is a basic indicator for alterations in two vital metabolic pathways: glycolysis and cellular respiration. Measuring these alterations by monitoring extracellular acidification using cell-based biosensors such as LAPS plays an important role in studying these pathways whose disorders are associated with numerous diseases including cancer. However, the surface of the biosensors must be specially tailored to ensure high cell compatibility so that cells can represent more in vivo-like behavior, which is critical to gain more realistic in vitro results from the analyses, e.g., drug discovery experiments. In this work, O2 plasma patterning on the LAPS surface is studied to enhance surface features of the sensor chip, e.g., wettability and biofunctionality. The surface treated with O2 plasma for 30 s exhibits enhanced cytocompatibility for adherent CHO–K1 cells, which promotes cell spreading and proliferation. The plasma-modified LAPS chip is then integrated into a microfluidic system, which provides two identical channels to facilitate differential measurements of the extracellular acidification of CHO–K1 cells. To the best of our knowledge, it is the first time that extracellular acidification within microfluidic channels is quantitatively visualized as differential (bio-)chemical images. Y1 - 2020 U6 - https://doi.org/10.1016/j.phmed.2020.100030 SN - 2352-4510 VL - 10 IS - 100030 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Engelmann, Ulrich M. A1 - Pourshahidi, Mohammad Ali A1 - Shalaby, Ahmed A1 - Krause, Hans-Joachim T1 - Probing particle size dependency of frequency mixing magnetic detection with dynamic relaxation simulation JF - Journal of Magnetism and Magnetic Materials N2 - Biomedical applications of magnetic nanoparticles (MNP) fundamentally rely on the particles’ magnetic relaxation as a response to an alternating magnetic field. The magnetic relaxation complexly depends on the interplay of MNP magnetic and physical properties with the applied field parameters. It is commonly accepted that particle core size is a major contributor to signal generation in all the above applications, however, most MNP samples comprise broad distribution spanning nm and more. Therefore, precise knowledge of the exact contribution of individual core sizes to signal generation is desired for optimal MNP design generally for each application. Specifically, we present a magnetic relaxation simulation-driven analysis of experimental frequency mixing magnetic detection (FMMD) for biosensing to quantify the contributions of individual core size fractions towards signal generation. Applying our method to two different experimental MNP systems, we found the most dominant contributions from approx. 20 nm sized particles in the two independent MNP systems. Additional comparison between freely suspended and immobilized MNP also reveals insight in the MNP microstructure, allowing to use FMMD for MNP characterization, as well as to further fine-tune its applicability in biosensing. Y1 - 2022 U6 - https://doi.org/10.1016/j.jmmm.2022.169965 SN - 0304-8853 VL - 563 IS - In progress, Art. No. 169965 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Achtsnicht, Stefan A1 - Tödter, Julia A1 - Niehues, Julia A1 - Telöken, Matthias A1 - Offenhäusser, Andreas A1 - Krause, Hans-Joachim A1 - Schröper, Florian T1 - 3D printed modular immunofiltration columns for frequency mixing-based multiplex magnetic immunodetection JF - Sensors N2 - For performing point-of-care molecular diagnostics, magnetic immunoassays constitute a promising alternative to established enzyme-linked immunosorbent assays (ELISA) because they are fast, robust and sensitive. Simultaneous detection of multiple biomolecular targets from one body fluid sample is desired. The aim of this work is to show that multiplex magnetic immunodetection based on magnetic frequency mixing by means of modular immunofiltration columns prepared for different targets is feasible. By calculations of the magnetic response signal, the required spacing between the modules was determined. Immunofiltration columns were manufactured by 3D printing and antibody immobilization was performed in a batch approach. It was shown experimentally that two different target molecules in a sample solution could be individually detected in a single assaying step with magnetic measurements of the corresponding immobilization filters. The arrangement order of the filters and of a negative control did not influence the results. Thus, a simple and reliable approach to multi-target magnetic immunodetection was demonstrated. Y1 - 2019 U6 - https://doi.org/10.3390/s19010148 SN - 1424-8220 VL - 19 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - Aliazizi, Fereshteh A1 - Özsoylu, Dua A1 - Bakhshi Sichani, Soroush A1 - Khorshid, Mehran A1 - Glorieux, Christ A1 - Robbens, Johan A1 - Schöning, Michael Josef A1 - Wagner, Patrick T1 - Development and Calibration of a Microfluidic, Chip-Based Sensor System for Monitoring the Physical Properties of Water Samples in Aquacultures JF - Micromachines N2 - In this work, we present a compact, bifunctional chip-based sensor setup that measures the temperature and electrical conductivity of water samples, including specimens from rivers and channels, aquaculture, and the Atlantic Ocean. For conductivity measurements, we utilize the impedance amplitude recorded via interdigitated electrode structures at a single triggering frequency. The results are well in line with data obtained using a calibrated reference instrument. The new setup holds for conductivity values spanning almost two orders of magnitude (river versus ocean water) without the need for equivalent circuit modelling. Temperature measurements were performed in four-point geometry with an on-chip platinum RTD (resistance temperature detector) in the temperature range between 2 °C and 40 °C, showing no hysteresis effects between warming and cooling cycles. Although the meander was not shielded against the liquid, the temperature calibration provided equivalent results to low conductive Milli-Q and highly conductive ocean water. The sensor is therefore suitable for inline and online monitoring purposes in recirculating aquaculture systems. KW - chip-based sensor setup KW - aquaculture KW - microfluidics KW - impedance spectroscopy KW - thermometry KW - electrical conductivity of liquids Y1 - 2024 U6 - https://doi.org/10.3390/mi15060755 SN - 2072-666X N1 - This article belongs to the Special Issue "Multisensor Arrays" N1 - Corresponding author: Michael J. Schöning VL - 15 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Falkenberg, Fabian A1 - Voß, Leonie A1 - Bott, Michael A1 - Bongaerts, Johannes A1 - Siegert, Petra T1 - New robust subtilisins from halotolerant and halophilic Bacillaceae JF - Applied Microbiology and Biotechnology N2 - The aim of the present study was the characterisation of three true subtilisins and one phylogenetically intermediate subtilisin from halotolerant and halophilic microorganisms. Considering the currently growing enzyme market for efficient and novel biocatalysts, data mining is a promising source for novel, as yet uncharacterised enzymes, especially from halophilic or halotolerant Bacillaceae, which offer great potential to meet industrial needs. Both halophilic bacteria Pontibacillus marinus DSM 16465ᵀ and Alkalibacillus haloalkaliphilus DSM 5271ᵀ and both halotolerant bacteria Metabacillus indicus DSM 16189 and Litchfieldia alkalitelluris DSM 16976ᵀ served as a source for the four new subtilisins SPPM, SPAH, SPMI and SPLA. The protease genes were cloned and expressed in Bacillus subtilis DB104. Purification to apparent homogeneity was achieved by ethanol precipitation, desalting and ion-exchange chromatography. Enzyme activity could be observed between pH 5.0–12.0 with an optimum for SPPM, SPMI and SPLA around pH 9.0 and for SPAH at pH 10.0. The optimal temperature for SPMI and SPLA was 70 °C and for SPPM and SPAH 55 °C and 50 °C, respectively. All proteases showed high stability towards 5% (w/v) SDS and were active even at NaCl concentrations of 5 M. The four proteases demonstrate potential for future biotechnological applications. KW - Biotechnological application KW - Bacillaceae KW - Subtilisin KW - Subtilases KW - Halotolerant protease Y1 - 2023 U6 - https://doi.org/10.1007/s00253-023-12553-w SN - 1432-0614 N1 - Corresponding author: Petra Siegert VL - 107 SP - 3939 EP - 3954 PB - Springer Nature CY - Berlin ER - TY - CHAP A1 - Kirchner, Patrick A1 - Henkel, H. A1 - Näther, Niko A1 - Spelthahn, H. A1 - Schneider, A. A1 - Berger, J. A1 - Kolstad, J. A1 - Friedrich, P. A1 - Schöning, Michael Josef T1 - RFID-basiertes Sensorsystem zur Realisierung intelligenter Verpackungen für die Nahrungsmittelindustrie T2 - KMU - innovativ: IKT 2008. CD-ROM : BMBF-Statustagung KMU - innovativ: IKT, Darmstadt, 17. - 18. Nov. 2008 Y1 - 2008 IS - CD-ROM-Ausg. PB - BMBF CY - Berlin ER - TY - JOUR A1 - Haeger, Gerrit A1 - Wirges, Jessika A1 - Tanzmann, Nicole A1 - Oyen, Sven A1 - Jolmes, Tristan A1 - Jaeger, Karl-Erich A1 - Schörken, Ulrich A1 - Bongaerts, Johannes A1 - Siegert, Petra T1 - Chaperone assisted recombinant expression of a mycobacterial aminoacylase in Vibrio natriegens and Escherichia coli capable of N-lauroyl-L-amino acid synthesis JF - Microbial Cell Factories N2 - Background Aminoacylases are highly promising enzymes for the green synthesis of acyl-amino acids, potentially replacing the environmentally harmful Schotten-Baumann reaction. Long-chain acyl-amino acids can serve as strong surfactants and emulsifiers, with application in cosmetic industries. Heterologous expression of these enzymes, however, is often hampered, limiting their use in industrial processes. Results We identified a novel mycobacterial aminoacylase gene from Mycolicibacterium smegmatis MKD 8, cloned and expressed it in Escherichia coli and Vibrio natriegens using the T7 overexpression system. The recombinant enzyme was prone to aggregate as inclusion bodies, and while V. natriegens Vmax™ could produce soluble aminoacylase upon induction with isopropyl β-d-1-thiogalactopyranoside (IPTG), E. coli BL21 (DE3) needed autoinduction with lactose to produce soluble recombinant protein. We successfully conducted a chaperone co-expression study in both organisms to further enhance aminoacylase production and found that overexpression of chaperones GroEL/S enhanced aminoacylase activity in the cell-free extract 1.8-fold in V. natriegens and E. coli. Eventually, E. coli ArcticExpress™ (DE3), which co-expresses cold-adapted chaperonins Cpn60/10 from Oleispira antarctica, cultivated at 12 °C, rendered the most suitable expression system for this aminoacylase and exhibited twice the aminoacylase activity in the cell-free extract compared to E. coli BL21 (DE3) with GroEL/S co-expression at 20 °C. The purified aminoacylase was characterized based on hydrolytic activities, being most stable and active at pH 7.0, with a maximum activity at 70 °C, and stability at 40 °C and pH 7.0 for 5 days. The aminoacylase strongly prefers short-chain acyl-amino acids with smaller, hydrophobic amino acid residues. Several long-chain amino acids were fairly accepted in hydrolysis as well, especially N-lauroyl-L-methionine. To initially evaluate the relevance of this aminoacylase for the synthesis of N-acyl-amino acids, we demonstrated that lauroyl-methionine can be synthesized from lauric acid and methionine in an aqueous system. Conclusion Our results suggest that the recombinant enzyme is well suited for synthesis reactions and will thus be further investigated. KW - Acyl-amino acids KW - Inclusion bodies KW - Chaperone co-expression KW - Vibrio natriegens KW - Aminoacylase Y1 - 2023 U6 - https://doi.org/10.1186/s12934-023-02079-1 SN - 1475-2859 N1 - Corresponding author: Petra Siegert IS - 22 SP - Article number: 77 (2023) PB - Springer Nature ER - TY - JOUR A1 - Welden, Melanie A1 - Poghossian, Arshak A1 - Vahidpour, Farnoosh A1 - Wendlandt, Tim A1 - Keusgen, Michael A1 - Wege, Christina A1 - Schöning, Michael Josef T1 - Towards multi-analyte detection with field-effect capacitors modified with tobacco mosaic virus bioparticles as enzyme nanocarriers JF - Biosensors N2 - Utilizing an appropriate enzyme immobilization strategy is crucial for designing enzyme-based biosensors. Plant virus-like particles represent ideal nanoscaffolds for an extremely dense and precise immobilization of enzymes, due to their regular shape, high surface-to-volume ratio and high density of surface binding sites. In the present work, tobacco mosaic virus (TMV) particles were applied for the co-immobilization of penicillinase and urease onto the gate surface of a field-effect electrolyte-insulator-semiconductor capacitor (EISCAP) with a p-Si-SiO₂-Ta₂O₅ layer structure for the sequential detection of penicillin and urea. The TMV-assisted bi-enzyme EISCAP biosensor exhibited a high urea and penicillin sensitivity of 54 and 85 mV/dec, respectively, in the concentration range of 0.1–3 mM. For comparison, the characteristics of single-enzyme EISCAP biosensors modified with TMV particles immobilized with either penicillinase or urease were also investigated. The surface morphology of the TMV-modified Ta₂O₅-gate was analyzed by scanning electron microscopy. Additionally, the bi-enzyme EISCAP was applied to mimic an XOR (Exclusive OR) enzyme logic gate. KW - urease KW - enzyme-logic gate KW - bi-enzyme biosensor KW - capacitive field-effect sensor KW - tobacco mosaic virus (TMV) KW - penicillinase Y1 - 2022 U6 - https://doi.org/10.3390/bios12010043 SN - 2079-6374 N1 - This article belongs to the Special Issue "Biosensors: 10th Anniversary Feature Papers" VL - 12 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - Pourshahidi, Ali Mohammad A1 - Achtsnicht, Stefan A1 - Offenhäusser, Andreas A1 - Krause, Hans-Joachim ED - Offenhäusser, Andreas T1 - Frequency Mixing Magnetic Detection Setup Employing Permanent Ring Magnets as a Static Offset Field Source JF - Sensors N2 - Frequency mixing magnetic detection (FMMD) has been explored for its applications in fields of magnetic biosensing, multiplex detection of magnetic nanoparticles (MNP) and the determination of core size distribution of MNP samples. Such applications rely on the application of a static offset magnetic field, which is generated traditionally with an electromagnet. Such a setup requires a current source, as well as passive or active cooling strategies, which directly sets a limitation based on the portability aspect that is desired for point of care (POC) monitoring applications. In this work, a measurement head is introduced that involves the utilization of two ring-shaped permanent magnets to generate a static offset magnetic field. A steel cylinder in the ring bores homogenizes the field. By variation of the distance between the ring magnets and of the thickness of the steel cylinder, the magnitude of the magnetic field at the sample position can be adjusted. Furthermore, the measurement setup is compared to the electromagnet offset module based on measured signals and temperature behavior. KW - magnetic sensors KW - biosensors KW - frequency mixing magnetic detection KW - magnetic nanoparticles Y1 - 2022 U6 - https://doi.org/10.3390/s22228776 SN - 1424-8220 VL - 22 IS - 22 PB - MDPI CY - Basel ER - TY - JOUR A1 - Falkenberg, Fabian A1 - Bott, Michael A1 - Bongaerts, Johannes A1 - Siegert, Petra T1 - Phylogenetic survey of the subtilase family and a data-mining-based search for new subtilisins from Bacillaceae JF - Frontiers in Microbiology N2 - The subtilase family (S8), a member of the clan SB of serine proteases are ubiquitous in all kingdoms of life and fulfil different physiological functions. Subtilases are divided in several groups and especially subtilisins are of interest as they are used in various industrial sectors. Therefore, we searched for new subtilisin sequences of the family Bacillaceae using a data mining approach. The obtained 1,400 sequences were phylogenetically classified in the context of the subtilase family. This required an updated comprehensive overview of the different groups within this family. To fill this gap, we conducted a phylogenetic survey of the S8 family with characterised holotypes derived from the MEROPS database. The analysis revealed the presence of eight previously uncharacterised groups and 13 subgroups within the S8 family. The sequences that emerged from the data mining with the set filter parameters were mainly assigned to the subtilisin subgroups of true subtilisins, high-alkaline subtilisins, and phylogenetically intermediate subtilisins and represent an excellent source for new subtilisin candidates. Y1 - 2022 U6 - https://doi.org/10.3389/fmicb.2022.1017978 SN - 1664-302X VL - 2022 IS - 13 PB - Frontiers CY - Lausanne ER - TY - JOUR A1 - Welden, Melanie A1 - Severins, Robin A1 - Poghossian, Arshak A1 - Wege, Christina A1 - Bongaerts, Johannes A1 - Siegert, Petra A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Detection of acetoin and diacetyl by a tobacco mosaic virus-assisted field-effect biosensor JF - Chemosensors N2 - Acetoin and diacetyl have a major impact on the flavor of alcoholic beverages such as wine or beer. Therefore, their measurement is important during the fermentation process. Until now, gas chromatographic techniques have typically been applied; however, these require expensive laboratory equipment and trained staff, and do not allow for online monitoring. In this work, a capacitive electrolyte–insulator–semiconductor sensor modified with tobacco mosaic virus (TMV) particles as enzyme nanocarriers for the detection of acetoin and diacetyl is presented. The enzyme acetoin reductase from Alkalihalobacillus clausii DSM 8716ᵀ is immobilized via biotin–streptavidin affinity, binding to the surface of the TMV particles. The TMV-assisted biosensor is electrochemically characterized by means of leakage–current, capacitance–voltage, and constant capacitance measurements. In this paper, the novel biosensor is studied regarding its sensitivity and long-term stability in buffer solution. Moreover, the TMV-assisted capacitive field-effect sensor is applied for the detection of diacetyl for the first time. The measurement of acetoin and diacetyl with the same sensor setup is demonstrated. Finally, the successive detection of acetoin and diacetyl in buffer and in diluted beer is studied by tuning the sensitivity of the biosensor using the pH value of the measurement solution. Y1 - 2022 U6 - https://doi.org/10.3390/chemosensors10060218 SN - 2227-9040 N1 - This article belongs to the Special Issue "Nanostructured Devices for Biochemical Sensing" VL - 10 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Karschuck, Tobias A1 - Kaulen, Corinna A1 - Poghossian, Arshak A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - Gold nanoparticle-modified capacitive field-effect sensors: Studying the surface density of nanoparticles and coupling of charged polyelectrolyte macromolecules JF - Electrochemical Science Advances N2 - The coupling of ligand-stabilized gold nanoparticles with field-effect devices offers new possibilities for label-free biosensing. In this work, we study the immobilization of aminooctanethiol-stabilized gold nanoparticles (AuAOTs) on the silicon dioxide surface of a capacitive field-effect sensor. The terminal amino group of the AuAOT is well suited for the functionalization with biomolecules. The attachment of the positively-charged AuAOTs on a capacitive field-effect sensor was detected by direct electrical readout using capacitance-voltage and constant capacitance measurements. With a higher particle density on the sensor surface, the measured signal change was correspondingly more pronounced. The results demonstrate the ability of capacitive field-effect sensors for the non-destructive quantitative validation of nanoparticle immobilization. In addition, the electrostatic binding of the polyanion polystyrene sulfonate to the AuAOT-modified sensor surface was studied as a model system for the label-free detection of charged macromolecules. Most likely, this approach can be transferred to the label-free detection of other charged molecules such as enzymes or antibodies. KW - polystyrene sulfonate KW - gold nanoparticles KW - field-effect sensor KW - detection of charged macromolecules KW - capacitive EIS sensor Y1 - 2021 U6 - https://doi.org/10.1002/elsa.202100179 SN - 0938-5193 VL - 2 IS - 5 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Haeger, Gerrit A1 - Jolmes, Tristan A1 - Oyen, Sven A1 - Jaeger, Karl-Erich A1 - Bongaerts, Johannes A1 - Schörken, Ulrich A1 - Siegert, Petra T1 - Novel recombinant aminoacylase from Paraburkholderia monticola capable of N-acyl-amino acid synthesis JF - Applied Microbiology and Biotechnology N2 - N-Acyl-amino acids can act as mild biobased surfactants, which are used, e.g., in baby shampoos. However, their chemical synthesis needs acyl chlorides and does not meet sustainability criteria. Thus, the identification of biocatalysts to develop greener synthesis routes is desirable. We describe a novel aminoacylase from Paraburkholderia monticola DSM 100849 (PmAcy) which was identified, cloned, and evaluated for its N-acyl-amino acid synthesis potential. Soluble protein was obtained by expression in lactose autoinduction medium and co-expression of molecular chaperones GroEL/S. Strep-tag affinity purification enriched the enzyme 16-fold and yielded 15 mg pure enzyme from 100 mL of culture. Biochemical characterization revealed that PmAcy possesses beneficial traits for industrial application like high temperature and pH-stability. A heat activation of PmAcy was observed upon incubation at temperatures up to 80 °C. Hydrolytic activity of PmAcy was detected with several N-acyl-amino acids as substrates and exhibited the highest conversion rate of 773 U/mg with N-lauroyl-L-alanine at 75 °C. The enzyme preferred long-chain acyl-amino-acids and displayed hardly any activity with acetyl-amino acids. PmAcy was also capable of N-acyl-amino acid synthesis with good conversion rates. The best synthesis results were obtained with the cationic L-amino acids L-arginine and L-lysine as well as with L-leucine and L-phenylalanine. Exemplarily, L-phenylalanine was acylated with fatty acids of chain lengths from C8 to C18 with conversion rates of up to 75%. N-lauroyl-L-phenylalanine was purified by precipitation, and the structure of the reaction product was verified by LC–MS and NMR. KW - Chaperone KW - Biocatalysis KW - Aminoacylase KW - Acylation KW - Acyl-amino acids KW - Biosurfactants Y1 - 2024 U6 - https://doi.org/10.1007/s00253-023-12868-8 SN - 1432-0614 N1 - Corresponding author: Petra Siegert IS - 108 PB - Springer CY - Berlin ER - TY - JOUR A1 - Schöning, Michael Josef A1 - Bronder, Thomas A1 - Wu, Chunsheng A1 - Scheja, Sabrina A1 - Jessing, Max A1 - Metzger-Boddien, Christoph A1 - Keusgen, Michael A1 - Poghossian, Arshak T1 - Label-Free DNA Detection with Capacitive Field-Effect Devices—Challenges and Opportunities JF - Proceedings N2 - Field-effect EIS (electrolyte-insulator-semiconductor) sensors modified with a positively charged weak polyelectrolyte layer have been applied for the electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge. The EIS sensors are able to detect the existence of target DNA amplicons in PCR (polymerase chain reaction) samples and thus, can be used as tool for a quick verification of DNA amplification and the successful PCR process. Due to their miniaturized setup, compatibility with advanced micro- and nanotechnologies, and ability to detect biomolecules by their intrinsic molecular charge, those sensors can serve as possible platform for the development of label-free DNA chips. Possible application fields as well as challenges and limitations will be discussed. Y1 - 2017 U6 - https://doi.org/10.3390/proceedings1080719 SN - 2504-3900 N1 - This article belongs to the Proceedings of "Proceedings of the 5th International Symposium on Sensor Science (I3S 2017)" VL - 1 IS - 8 SP - Artikel 719 PB - MDPI CY - Basel ER - TY - JOUR A1 - Poghossian, Arshak A1 - Welden, Rene A1 - Buniatyan, Vahe V. A1 - Schöning, Michael Josef T1 - An Array of On-Chip Integrated, Individually Addressable Capacitive Field-Effect Sensors with Control Gate: Design and Modelling JF - Sensors N2 - The on-chip integration of multiple biochemical sensors based on field-effect electrolyte-insulator-semiconductor capacitors (EISCAP) is challenging due to technological difficulties in realization of electrically isolated EISCAPs on the same Si chip. In this work, we present a new simple design for an array of on-chip integrated, individually electrically addressable EISCAPs with an additional control gate (CG-EISCAP). The existence of the CG enables an addressable activation or deactivation of on-chip integrated individual CG-EISCAPs by simple electrical switching the CG of each sensor in various setups, and makes the new design capable for multianalyte detection without cross-talk effects between the sensors in the array. The new designed CG-EISCAP chip was modelled in so-called floating/short-circuited and floating/capacitively-coupled setups, and the corresponding electrical equivalent circuits were developed. In addition, the capacitance-voltage curves of the CG-EISCAP chip in different setups were simulated and compared with that of a single EISCAP sensor. Moreover, the sensitivity of the CG-EISCAP chip to surface potential changes induced by biochemical reactions was simulated and an impact of different parameters, such as gate voltage, insulator thickness and doping concentration in Si, on the sensitivity has been discussed. KW - equivalent circuit KW - multianalyte detection KW - control gate KW - on-chip integrated addressable EISCAP sensors KW - capacitive field-effect sensor Y1 - 2021 U6 - https://doi.org/10.3390/s21186161 SN - 1424-8220 N1 - This article belongs to the Special Issue "Field-Effect Sensors: From pH Sensing to Biosensing" VL - 21 IS - 18 SP - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Vahidpour, Farnoosh A1 - Guthman, Eric A1 - Arreola, Julia A1 - Alghazali, Yousef H. M. A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Assessment of Various Process Parameters for Optimized Sterilization Conditions Using a Multi-Sensing Platform JF - Foods N2 - In this study, an online multi-sensing platform was engineered to simultaneously evaluate various process parameters of food package sterilization using gaseous hydrogen peroxide (H₂O₂). The platform enabled the validation of critical aseptic parameters. In parallel, one series of microbiological count reduction tests was performed using highly resistant spores of B. atrophaeus DSM 675 to act as the reference method for sterility validation. By means of the multi-sensing platform together with microbiological tests, we examined sterilization process parameters to define the most effective conditions with regards to the highest spore kill rate necessary for aseptic packaging. As these parameters are mutually associated, a correlation between different factors was elaborated. The resulting correlation indicated the need for specific conditions regarding the applied H₂O₂ gas temperature, the gas flow and concentration, the relative humidity and the exposure time. Finally, the novel multi-sensing platform together with the mobile electronic readout setup allowed for the online and on-site monitoring of the sterilization process, selecting the best conditions for sterility and, at the same time, reducing the use of the time-consuming and costly microbiological tests that are currently used in the food package industry. KW - spore kill rate KW - sterility KW - aseptic parameters KW - multi-sensing platform KW - gaseous hydrogen peroxide Y1 - 2022 U6 - https://doi.org/10.3390/foods11050660 SN - 2304-8158 N1 - This article belongs to the Special Issue "Sensors and Biosensors Application for Food Industries" VL - 11 IS - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Poghossian, Arshak A1 - Karschuck, Tobias A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Field-Effect Capacitors Decorated with Ligand-Stabilized Gold Nanoparticles: Modeling and Experiments JF - Biosensors N2 - Nanoparticles are recognized as highly attractive tunable materials for designing field-effect biosensors with enhanced performance. In this work, we present a theoretical model for electrolyte-insulator-semiconductor capacitors (EISCAP) decorated with ligand-stabilized charged gold nanoparticles. The charged AuNPs are taken into account as additional, nanometer-sized local gates. The capacitance-voltage (C–V) curves and constant-capacitance (ConCap) signals of the AuNP-decorated EISCAPs have been simulated. The impact of the AuNP coverage on the shift of the C–V curves and the ConCap signals was also studied experimentally on Al–p-Si–SiO₂ EISCAPs decorated with positively charged aminooctanethiol-capped AuNPs. In addition, the surface of the EISCAPs, modified with AuNPs, was characterized by scanning electron microscopy for different immobilization times of the nanoparticles. KW - aminooctanethiol KW - nanoparticle coverage KW - capacitive model KW - gold nanoparticles KW - field-effect sensor KW - electrolyte-insulator-semiconductor capacitors Y1 - 2022 U6 - https://doi.org/10.3390/bios12050334 SN - 2079-6374 N1 - This article belongs to the Special Issue "Biosensors in Nanotechnology" VL - 12 IS - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Abulnaga, El-Hussiny A1 - Pinkenburg, Olaf A1 - Schiffels, Johannes A1 - E-Refai, Ahmed A1 - Buckel, Wolfgang A1 - Selmer, Thorsten T1 - Effect of an Oxygen-Tolerant Bifurcating Butyryl Coenzyme A Dehydrogenase/Electron-Transferring Flavoprotein Complex from Clostridium difficile on Butyrate Production in Escherichia coli JF - Journal of bacteriology Y1 - 2013 SN - 1098-5530 [E-Journal] SN - 0021-9193 [Print] VL - 195 IS - 16 SP - 3704 EP - 3713 ER - TY - JOUR A1 - Bronder, Thomas A1 - Jessing, Max P. A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Detection of PCR-Amplified Tuberculosis DNA Fragments with Polyelectrolyte-Modified Field-Effect Sensors JF - Analytical Chemistry N2 - Field-effect-based electrolyte-insulator-semiconductor (EIS) sensors were modified with a bilayer of positively charged weak polyelectrolyte (poly(allylamine hydrochloride) (PAH)) and probe single-stranded DNA (ssDNA) and are used for the detection of complementary single-stranded target DNA (cDNA) in different test solutions. The sensing mechanism is based on the detection of the intrinsic molecular charge of target cDNA molecules after the hybridization event between cDNA and immobilized probe ssDNA. The test solutions contain synthetic cDNA oligonucleotides (with a sequence of tuberculosis mycobacteria genome) or PCR-amplified DNA (which origins from a template DNA strand that has been extracted from Mycobacterium avium paratuberculosis-spiked human sputum samples), respectively. Sensor responses up to 41 mV have been measured for the test solutions with DNA, while only small signals of ∼5 mV were detected for solutions without DNA. The lower detection limit of the EIS sensors was ∼0.3 nM, and the sensitivity was ∼7.2 mV/decade. Fluorescence experiments using SybrGreen I fluorescence dye support the electrochemical results. Y1 - 2018 U6 - https://doi.org/10.1021/acs.analchem.8b01807 SN - 0003-2700 VL - 90 IS - 12 SP - 7747 EP - 7753 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Oberländer, Jan A1 - Kirchner, Patrick A1 - Keusgen, Michael A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - Experimental and Numerical Analyzes of a Sensor Based on Interdigitated Electrodes for Studying Microbiological Alterations JF - physica status solidi (a): applications and materials science N2 - In this work, a cell-based biosensor to evaluate the sterilization efficacy of hydrogen peroxide vapor sterilization processes is characterized. The transducer of the biosensor is based on interdigitated gold electrodes fabricated on an inert glass substrate. Impedance spectroscopy is applied to evaluate the sensor behavior and the alteration of test microorganisms due to the sterilization process. These alterations are related to changes in relative permittivity and electrical conductivity of the bacterial spores. Sensor measurements are conducted with and without bacterial spores (Bacillus atrophaeus), as well as after an industrial sterilization protocol. Equivalent two-dimensional numerical models based on finite element method of the periodic finger structures of the interdigitated gold electrodes are designed and validated using COMSOL® Multiphysics software by the application of known dielectric properties. The validated models are used to compute the electrical properties at different sensor states (blank, loaded with spores, and after sterilization). As a final result, we will derive and tabulate the frequency-dependent electrical parameters of the spore layer using a novel model that combines experimental data with numerical optimization techniques. Y1 - 2018 U6 - https://doi.org/10.1002/pssa.201700920 SN - 1862-6319 VL - 215 IS - 15 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Molinnus, Denise A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Katz, Evgeny A1 - Schöning, Michael Josef T1 - Coupling of Biomolecular Logic Gates with Electronic Transducers: From Single Enzyme Logic Gates to Sense/Act/Treat Chips JF - Electroanalysis N2 - The integration of biomolecular logic principles with electronic transducers allows designing novel digital biosensors with direct electrical output, logically triggered drug-release, and closed-loop sense/act/treat systems. This opens new opportunities for advanced personalized medicine in the context of theranostics. In the present work, we will discuss selected examples of recent developments in the field of interfacing enzyme logic gates with electrodes and semiconductor field-effect devices. Special attention is given to an enzyme OR/Reset logic gate based on a capacitive field-effect electrolyte-insulator-semiconductor sensor modified with a multi-enzyme membrane. Further examples are a digital adrenaline biosensor based on an AND logic gate with binary YES/NO output and an integrated closed-loop sense/act/treat system comprising an amperometric glucose sensor, a hydrogel actuator, and an insulin (drug) sensor. Y1 - 2017 U6 - https://doi.org/10.1002/elan.201700208 SN - 1521-4109 VL - 29 IS - 8 SP - 1840 EP - 1849 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Abouzar, Maryam H. A1 - Schöning, Michael Josef A1 - Poghossian, Arshak A1 - Christiaens, P. A1 - Williams, O. A. A1 - Wagner, P. A1 - Haenen, K. T1 - Feldeffektsensor auf nanokristalliner Diamantbasis JF - Sensoren und Messsysteme 2008 : 14. Fachtagung Ludwigsburg, 11. und 12. März 2008 / VDI/VDE-Gesellschaft Mess- und Automatisierungstechnik Y1 - 2008 SN - 978-3-18-092011-5 N1 - VDI-Berichte ; 2011 ; Sensoren und Messsysteme 2008, 14. GMA/ITG-Fachtagung, VDI/VDE- Gesellschaft Mess- und Automatisierungstechnik, + CD-ROM, Ludwigsburg, DE, 11.-12. Mar, 2008 SP - 549 EP - 558 PB - VDI-Verl. CY - Düsseldorf ER - TY - CHAP A1 - Platen, Johannes A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Microstructured Nanostructures – nanostructuring by means of conventional photolithography and layer-expansion technique N2 - A new and simple method for nanostructuring using conventional photolithography and layer expansion or pattern-size reduction technique is presented, which can further be applied for the fabrication of different nanostructures and nano-devices. The method is based on the conversion of a photolithographically patterned metal layer to a metal-oxide mask with improved pattern-size resolution using thermal oxidation. With this technique, the pattern size can be scaled down to several nanometer dimensions. The proposed method is experimentally demonstrated by preparing nanostructures with different configurations and layouts, like circles, rectangles, trapezoids, “fluidic-channel”-, “cantilever”- and meander-type structures. KW - Biosensor KW - Nanostructuring KW - layer expansion KW - pattern-size reduction KW - self-aligned patterning Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:a96-opus-1477 ER - TY - JOUR A1 - Kloock, Joachim P. A1 - Poghossian, Arshak A1 - Schumacher, K. A1 - Rosenkranz, C. A1 - Schultze, J. W. A1 - Müller-Veggian, Mattea A1 - Schöning, Michael Josef T1 - Funktionsprüfung und Charakterisierung von ionensensitiven Feldeffekttransistoren (ISFETs) auf Waferebene mittels Mikrotropfenzelle für den zukünftigen Einsatz in der Sensorproduktion JF - Sensoren und Messsysteme 2006 : Vorträge der 13. ITG/GMA-Fachtagung vom 13. bis 14. März 2006 in Freiburg/Breisgau / Veranst.: Informationstechnische Gesellschaft im VDE (ITG) ; VDE/VDI-Gesellschaft Mess- und Automatisierungstechnik (GMA). Wiss. Tagungsleitung: L. M. Reindl Y1 - 2006 SN - 3-8007-2939-3 N1 - Fachtagung Sensoren und Messsysteme <13, 2006, Freiburg, Breisgau> SP - 257 EP - 260 PB - VDE-Verl. CY - Berlin ER - TY - CHAP A1 - Schöning, Michael Josef A1 - Wagner, Torsten A1 - Poghossian, Arshak A1 - Miyamoto, K.I. A1 - Werner, C.F. A1 - Krause, S. A1 - Yoshinobu, T. T1 - Light-addressable potentiometric sensors for (bio-)chemical sensing and imaging T2 - Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry. Vol. 7 Y1 - 2018 SN - 9780128097397 SP - 295 EP - 308 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Poghossian, Arshak A1 - Yoshinobu, Tatsuo A1 - Simonis, A. A1 - Ecken, H. A1 - Lüth, Hans A1 - Schöning, Michael Josef T1 - Penicillin detection by means of field-effect based sensors: EnFET, capacitive EIS sensor or LAPS? JF - Sensors and Actuators B. 78 (2001), H. 1-3 Y1 - 2001 SN - 0925-4005 SP - 237 EP - 242 ER - TY - CHAP A1 - Schöning, Michael Josef A1 - Abouzar, Maryam H. A1 - Han, Y. A1 - Ingebrandt, S. A1 - Offenhäusser, A. A1 - Poghossian, Arshak T1 - Markierungsfreie DNA-Detektion mit Silizium-Feldeffektsensoren – Messeffekte oder Artefakte? T2 - Sensoren und Mess-Systeme 2006 : Vorträge der 13. ITG/GMA-Fachtagung vom 13. bis 14.3.2006 in Freiburg/Breisgau Y1 - 2006 SN - 3-8007-2939-3 SP - 443 EP - 446 PB - VDE Verl. CY - Berlin ER - TY - JOUR A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - Chemical and biological field-effect sensors for liquids – a status report JF - Handbook of biosensors and biochips / ed. Robert S. Marks ... Bd. 1 Y1 - 2007 SN - 978-0-470-01905-4 SP - 395 EP - 412 PB - Wiley CY - Chichester ER - TY - JOUR A1 - Poghossian, Arshak A1 - Weil, M. A1 - Cherstvy, A. G. A1 - Schöning, Michael Josef T1 - Electrical monitoring of polyelectrolyte multilayer formation by means of capacitive field-effect devices JF - Analytical and bioanalytical chemistry N2 - The semiconductor field-effect platform represents a powerful tool for detecting the adsorption and binding of charged macromolecules with direct electrical readout. In this work, a capacitive electrolyte–insulator–semiconductor (EIS) field-effect sensor consisting of an Al-p-Si-SiO2 structure has been applied for real-time in situ electrical monitoring of the layer-by-layer formation of polyelectrolyte (PE) multilayers (PEM). The PEMs were deposited directly onto the SiO2 surface without any precursor layer or drying procedures. Anionic poly(sodium 4-styrene sulfonate) and cationic weak polyelectrolyte poly(allylamine hydrochloride) have been chosen as a model system. The effect of the ionic strength of the solution, polyelectrolyte concentration, number and polarity of the PE layers on the characteristics of the PEM-modified EIS sensors have been studied by means of capacitance–voltage and constant-capacitance methods. In addition, the thickness, surface morphology, roughness and wettabilityof the PE mono- and multilayers have been characterised by ellipsometry, atomic force microscopy and water contact-angle methods, respectively. To explain potential oscillations on the gate surface and signal behaviour of the capacitive field-effect EIS sensor modified with a PEM, a simplified electrostatic model that takes into account the reduced electrostatic screening of PE charges by mobile ions within the PEM has been proposed and discussed. Y1 - 2013 U6 - https://doi.org/10.1007/s00216-013-6951-9 SN - 1432-1130 ; 1618-2642 VL - 405 IS - 20 SP - 6425 EP - 6436 PB - Springer CY - Berlin ER - TY - CHAP A1 - Wu, Chunsheng A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Schöning, Michael Josef T1 - DNA-hybridization detection using light-addressable potentiometric sensor modified with gold layer T2 - Sensoren und Messsysteme 2014 ; Beiträge der 17. GMA/ITG-Fachtagung vom 3. bis 4. Juni 2014 in Nürnberg. (ITG-Fachbericht ; 250) Y1 - 2014 SN - 978-3-8007-3622-5 SP - 1 EP - 4 PB - VDE-Verl. CY - Düsseldorf ER - TY - CHAP A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Buniatyan, V. A1 - Schöning, Michael Josef T1 - Multi-parameter detection for supporting monitoring and control of biogas processes in agriculture T2 - Sensoren und Messsysteme 2014 ; Beiträge der 17. GMA/ITG-Fachtagung vom 3. bis 4. Juni 2014 in Nürnberg. (ITG-Fachbericht ; 250) Y1 - 2014 SN - 978-3-8007-3622-5 SP - 1 EP - 5 PB - VDE-Verl. CY - Berlin ER - TY - CHAP A1 - Schöning, Michael Josef A1 - Poghossian, Arshak A1 - Glück, Olaf A1 - Thust, Marion T1 - Electrochemical methods for the determination of chemical variables in aqueous media T2 - Measurement, instrumentation, and sensors handbook / ed. by John G. Webster [u.a.] Vol. 2 : Electromagnetic, optical, radiation, chemical, and biomedical measurement Y1 - 2014 SN - 978-1-4398-4891-3 SP - 55-1 EP - 55-54 PB - CRC Pr. CY - Boca Raton, Fla. ER - TY - JOUR A1 - Knobbe, D.-T. A1 - Schöning, Michael Josef A1 - Poghossian, Arshak A1 - Mourzina, Y. T1 - Charakterisierung von kapazitiven EMISSensoren mittels Impedanzspektroskopie, Kapazitäts-Spannungs- und Konstant-Kapazitäts-Messung JF - Sensoren und Messsysteme 2004 : Tagung Ludwigsburg, 15. und 16. März 2004 / VDI-VDE-Gesellschaft Mess- und Automatisierungstechnik Y1 - 2004 SN - 3-18-091829-2 N1 - Auch erschienen als: VDI-Berichte ; 1829 SP - 851 EP - 854 PB - VDI CY - Düsseldorf ER - TY - JOUR A1 - Molinnus, Denise A1 - Bäcker, Matthias A1 - Siegert, Petra A1 - Willenberg, H. A1 - Poghossian, Arshak A1 - Keusgen, M. A1 - Schöning, Michael Josef T1 - Detection of Adrenaline Based on Substrate Recycling Amplification JF - Procedia Engineering N2 - An amperometric enzyme biosensor has been applied for the detection of adrenaline. The adrenaline biosensor has been prepared by modification of an oxygen electrode with the enzyme laccase that operates at a broad pH range between pH 3.5 to pH 8. The enzyme molecules were immobilized via cross-linking with glutaraldehyde. The sensitivity of the developed adrenaline biosensor in different pH buffer solutions has been studied. Y1 - 2015 U6 - https://doi.org/10.1016/j.proeng.2015.08.708 SN - 1877-7058 N1 - Eurosensors 2015 VL - 120 SP - 540 EP - 543 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 -