@article{PoghossianSchoening2020,
  author    = {Poghossian, Arshak and Sch{\"o}ning, Michael Josef},
  title     = {Capacitive field-effect eis chemical sensors and biosensors: A status report},
  series = {Sensors},
  volume    = {20},
  journal   = {Sensors},
  number    = {19},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s20195639},
  pages     = {Artikel 5639},
  year      = {2020},
  abstract  = {Electrolyte-insulator-semiconductor (EIS) field-effect sensors belong to a new generation of electronic chips for biochemical sensing, enabling a direct electronic readout. The review gives an overview on recent advances and current trends in the research and development of chemical sensors and biosensors based on the capacitive field-effect EIS structure—the simplest field-effect device, which represents a biochemically sensitive capacitor. Fundamental concepts, physicochemical phenomena underlying the transduction mechanism and application of capacitive EIS sensors for the detection of pH, ion concentrations, and enzymatic reactions, as well as the label-free detection of charged molecules (nucleic acids, proteins, and polyelectrolytes) and nanoparticles, are presented and discussed.},
  language  = {en}
}
@book{YoshinobuSchoening2020,
  author    = {Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  title     = {Light-addressing and chemical imaging technologies for electrochemical sensing},
  editor    = {Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  publisher = {MDPI},
  address   = {Basel},
  isbn      = {978-3-03943-029-1},
  doi       = {10.3390/books978-3-03943-029-1},
  pages     = {122 Pages},
  year      = {2020},
  language  = {en}
}
@article{DantismRoehlenDahmenetal.2020,
  author    = {Dantism, Shahriar and R{\"o}hlen, Desiree and Dahmen, Markus and Wagner, Torsten and Wagner, Patrick and Sch{\"o}ning, Michael Josef},
  title     = {LAPS-based monitoring of metabolic responses of bacterial cultures in a paper fermentation broth},
  series = {Sensors and Actuators B: Chemical},
  volume    = {320},
  journal   = {Sensors and Actuators B: Chemical},
  number    = {Art. 128232},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2020.128232},
  year      = {2020},
  abstract  = {As an alternative renewable energy source, methane production in biogas plants is gaining more and more attention. Biomass in a bioreactor contains different types of microorganisms, which should be considered in terms of process-stability control. Metabolically inactive microorganisms within the fermentation process can lead to undesirable, time-consuming and cost-intensive interventions. Hence, monitoring of the cellular metabolism of bacterial populations in a fermentation broth is crucial to improve the biogas production, operation efficiency, and sustainability. In this work, the extracellular acidification of bacteria in a paper-fermentation broth is monitored after glucose uptake, utilizing a differential light-addressable potentiometric sensor (LAPS) system. The LAPS system is loaded with three different model microorganisms (Escherichia coli, Corynebacterium glutamicum, and Lactobacillus brevis) and the effect of the fermentation broth at different process stages on the metabolism of these bacteria is studied. In this way, different signal patterns related to the metabolic response of microorganisms can be identified. By means of calibration curves after glucose uptake, the overall extracellular acidification of bacterial populations within the fermentation process can be evaluated.},
  language  = {en}
}
@article{MennickenPeterKaulenetal.2020,
  author    = {Mennicken, Max and Peter, Sophia K. and Kaulen, Corinna and Simon, Ulrich and Karth{\"a}user, Silvia},
  title     = {Transport through Redox-Active Ru-Terpyridine Complexes Integrated in Single Nanoparticle Devices},
  series = {The Journal of Physical Chemistry C},
  volume    = {124},
  journal   = {The Journal of Physical Chemistry C},
  number    = {8},
  publisher = {ACS Publications},
  address   = {Washington, DC},
  issn      = {1932-7455},
  doi       = {10.1021/acs.jpcc.9b11716},
  pages     = {4881 -- 4889},
  year      = {2020},
  abstract  = {Transition metal complexes are electrofunctional molecules due to their high conductivity and their intrinsic switching ability involving a metal-to-ligand charge transfer. Here, a method is presented to contact reliably a few to single redox-active Ru-terpyridine complexes in a CMOS compatible nanodevice and preserve their electrical functionality. Using hybrid materials from 14 nm gold nanoparticles (AuNP) and bis-{4′-[4-(mercaptophenyl)-2,2′:6′,2″-terpyridine]}-ruthenium(II) complexes a device size of 30² nm² inclusive nanoelectrodes is achieved. Moreover, this method bears the opportunity for further downscaling. The Ru-complex AuNP devices show symmetric and asymmetric current versus voltage curves with a hysteretic characteristic in two well separated conductance ranges. By theoretical approximations based on the single-channel Landauer model, the charge transport through the formed double-barrier tunnel junction is thoroughly analyzed and its sensibility to the molecule/metal contact is revealed. It can be verified that tunneling transport through the HOMO is the main transport mechanism while decoherent hopping transport is present to a minor extent.},
  language  = {en}
}
@article{JildehKirchnerOberlaenderetal.2020,
  author    = {Jildeh, Zaid B. and Kirchner, Patrick and Oberl{\"a}nder, Jan and Vahidpour, Farnoosh and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef},
  title     = {Development of a package-sterilization process for aseptic filling machines: A numerical approach and validation for surface treatment with hydrogen peroxide},
  series = {Sensor and Actuators A: Physical},
  volume    = {303},
  journal   = {Sensor and Actuators A: Physical},
  number    = {111691},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0924-4247},
  doi       = {10.1016/j.sna.2019.111691},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@article{MuschallikMolinnusJablonskietal.2020,
  author    = {Muschallik, Lukas and Molinnus, Denise and Jablonski, Melanie and Kipp, Carina Ronja and Bongaerts, Johannes and Pohl, Martina and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Selmer, Thorsten and Siegert, Petra},
  title     = {Synthesis of α-hydroxy ketones and vicinal (R, R)-diols by Bacillus clausii DSM 8716ᵀ butanediol dehydrogenase},
  series = {RSC Advances},
  volume    = {10},
  journal   = {RSC Advances},
  publisher = {Royal Society of Chemistry (RSC)},
  address   = {Cambridge},
  issn      = {2046-2069},
  doi       = {10.1039/D0RA02066D},
  pages     = {12206 -- 12216},
  year      = {2020},
  abstract  = {α-hydroxy ketones (HK) and 1,2-diols are important building blocks for fine chemical synthesis. Here, we describe the R-selective 2,3-butanediol dehydrogenase from B. clausii DSM 8716ᵀ (BcBDH) that belongs to the metal-dependent medium chain dehydrogenases/reductases family (MDR) and catalyzes the selective asymmetric reduction of prochiral 1,2-diketones to the corresponding HK and, in some cases, the reduction of the same to the corresponding 1,2-diols. Aliphatic diketones, like 2,3-pentanedione, 2,3-hexanedione, 5-methyl-2,3-hexanedione, 3,4-hexanedione and 2,3-heptanedione are well transformed. In addition, surprisingly alkyl phenyl dicarbonyls, like 2-hydroxy-1-phenylpropan-1-one and phenylglyoxal are accepted, whereas their derivatives with two phenyl groups are not substrates. Supplementation of Mn²⁺ (1 mM) increases BcBDH's activity in biotransformations. Furthermore, the biocatalytic reduction of 5-methyl-2,3-hexanedione to mainly 5-methyl-3-hydroxy-2-hexanone with only small amounts of 5-methyl-2-hydroxy-3-hexanone within an enzyme membrane reactor is demonstrated.},
  language  = {en}
}
@article{WeldenSchoeningWagneretal.2020,
  author    = {Welden, Rene and Sch{\"o}ning, Michael Josef and Wagner, Patrick H. and Wagner, Torsten},
  title     = {Light-Addressable Electrodes for Dynamic and Flexible Addressing of Biological Systems and Electrochemical Reactions},
  series = {Sensors},
  volume    = {20},
  journal   = {Sensors},
  number    = {6},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s20061680},
  pages     = {Artikel 1680},
  year      = {2020},
  abstract  = {In this review article, we are going to present an overview on possible applications of light-addressable electrodes (LAE) as actuator/manipulation devices besides classical electrode structures. For LAEs, the electrode material consists of a semiconductor. Illumination with a light source with the appropiate wavelength leads to the generation of electron-hole pairs which can be utilized for further photoelectrochemical reaction. Due to recent progress in light-projection technologies, highly dynamic and flexible illumination patterns can be generated, opening new possibilities for light-addressable electrodes. A short introduction on semiconductor-electrolyte interfaces with light stimulation is given together with electrode-design approaches. Towards applications, the stimulation of cells with different electrode materials and fabrication designs is explained, followed by analyte-manipulation strategies and spatially resolved photoelectrochemical deposition of different material types.},
  language  = {en}
}
@phdthesis{Bronder2020,
  author    = {Bronder, Thomas},
  title     = {Label-free detection of tuberculosis DNA with capacitive field-effect biosensors},
  publisher = {Philipps-Universit{\"a}t Marburg},
  address   = {Marburg},
  doi       = {10.17192/z2021.0056},
  pages     = {X, 162 S},
  year      = {2020},
  language  = {en}
}
@phdthesis{Achtsnicht2020,
  author    = {Achtsnicht, Stefan},
  title     = {Multiplex-Magnetdetektion von superparamagnetischen Beads zur Identifizierung von Trinkwasserkontaminationen},
  doi       = {10.18154/RWTH-2020-12052},
  pages     = {144 Seiten},
  year      = {2020},
  abstract  = {Die qualitative und quantitative Detektion von Zielsubstanzen innerhalb einer w{\"a}ssrigen Probe ist f{\"u}r viele Fragestellungen von Interesse, etwa bei der Detektion von Kontaminationen in Trinkwasser in Krisensituationen. Hierbei ist es nicht nur wichtig, dass Pathogene m{\"o}glichst sensitiv detektiert werden k{\"o}nnen, sondern auch, dass die Analyse schnell erfolgt, um Betroffenen im Katastrophenfall z{\"u}gig sicheres Trinkwasser zu Verf{\"u}gung stellen zu k{\"o}nnen. Da bei einem solchen Szenario nicht von einer in der N{\"a}he 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 m{\"o}glich ist. Dabei werden die MBs mit Hilfe von prim{\"a}ren Antik{\"o}rpern an die Zielsubstanz gebunden und mit sekund{\"a}ren Antik{\"o}rpern an die Poren-Oberfl{\"a}che eines Polyethylen-Filters fixiert (Sandwich-Immunoassay). So kann die Quantifizierung der Zielsubstanz auf eine magnetische Messung der immobilisierten MB-Marker zur{\"u}ckgef{\"u}hrt 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 Handheldger{\"a}t realisiert wurde. Zus{\"a}tzlich 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 M{\"o}glichkeit zur Sensitivit{\"a}tssteigerung ist die magnetische Aufkonzentration, indem vor der magnetischen Analyse eine Separation der MBs aus einem gr{\"o}ßeren Probenvolumen mittels magnetischem Feldgradienten durchgef{\"u}hrt 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 Ans{\"a}tze entwickelt und getestet, die einen solchen multiparametrischen magnetischen Immunoassay erm{\"o}glichen. Einerseits wurde eine r{\"a}umliche Separation der Bindungsbereiche f{\"u}r verschiedene Zielsubstanzen realisiert, die sequentiell ausgewertet werden k{\"o}nnen. Andererseits wurde die Unterscheidung von verschiedenen Zielsubstanzen anhand der Charakteristika der an sie gebundenen, verschieden funktionalisierten MB-Typen untersucht. F{\"u}r eine solche Unterscheidung wurde zum einen die Anregefrequenz der magnetischen Frequenzmischtechnik w{\"a}hrend 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 bin{\"a}ren Mischung zweier verschiedener MB-Typen als gradueller {\"U}bergang der Verl{\"a}ufe der beiden reinen MB-L{\"o}sungen ergibt. Eine weitere Analysemethode f{\"u}r einen multiparametrischen Immunoassay besteht darin, ein zus{\"a}tzliches einstellbares statisches magnetisches Offsetfeld zu verwenden. Hierf{\"u}r 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 f{\"u}r MBs mit unterschiedlichen magnetischen Partikelmomenten m{\"o}glich 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.},
  language  = {de}
}
@article{ArreolaKeusgenSchoening2019,
  author    = {Arreola, Julio and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Toward an immobilization method for spore-based biosensors in oxidative environment},
  series = {Electrochimica Acta},
  volume    = {302},
  journal   = {Electrochimica Acta},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.electacta.2019.01.148},
  pages     = {394 -- 401},
  year      = {2019},
  language  = {en}
}
@article{BronderPoghossianJessingetal.2019,
  author    = {Bronder, Thomas and Poghossian, Arshak and Jessing, Max P. and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Surface regeneration and reusability of label-free DNA biosensors based on weak polyelectrolyte-modified capacitive field-effect structures},
  series = {Biosensors and Bioelectronics},
  volume    = {126},
  journal   = {Biosensors and Bioelectronics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0956-5663},
  doi       = {10.1016/j.bios.2018.11.019},
  pages     = {510 -- 517},
  year      = {2019},
  language  = {en}
}
@article{MoraisSilvaDantasetal.2019,
  author    = {Morais, Paulo V. and Silva, Anielle C. A. and Dantas, Noelio O. and Sch{\"o}ning, Michael Josef and Siqueira, Jos{\´e} R., Jr.},
  title     = {Hybrid Layer-by-Layer Film of Polyelectrolytes-Embedded Catalytic CoFe2O4 Nanocrystals as Sensing Units in Capacitive Electrolyte-Insulator-Semiconductor Devices},
  series = {physica status solidi a : applications and materials sciences},
  volume    = {216},
  journal   = {physica status solidi a : applications and materials sciences},
  number    = {1900044},
  publisher = {Wiley},
  address   = {Weinheim},
  doi       = {10.1002/pssa.201900044},
  pages     = {1 -- 9},
  year      = {2019},
  language  = {en}
}
@article{CornelisGivanoudiYongabietal.2019,
  author    = {Cornelis, Peter and Givanoudi, Stella and Yongabi, Derick and Iken, Heiko and Duw{\´e}, Sam and Deschaume, Olivier and Robbens, Johan and Dedecker, Peter and Bartic, Carmen and W{\"u}bbenhorst, Michael and Sch{\"o}ning, Michael Josef and Heyndrickx, Marc and Wagner, Patrick},
  title     = {Sensitive and specific detection of E. coli using biomimetic receptors in combination with a modified heat-transfer method},
  series = {Biosensors and Bioelectronics},
  volume    = {136},
  journal   = {Biosensors and Bioelectronics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0956-5663},
  doi       = {10.1016/j.bios.2019.04.026},
  pages     = {97 -- 105},
  year      = {2019},
  language  = {en}
}
@article{PoghossianGeisslerSchoening2019,
  author    = {Poghossian, Arshak and Geissler, Hanno and Sch{\"o}ning, Michael Josef},
  title     = {Rapid methods and sensors for milk quality monitoring and spoilage detection},
  series = {Biosensors and Bioelectronics},
  volume    = {140},
  journal   = {Biosensors and Bioelectronics},
  number    = {Article 111272},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0956-5663},
  doi       = {10.1016/j.bios.2019.04.040},
  year      = {2019},
  language  = {en}
}
@article{SchiffelsSelmer2019,
  author    = {Schiffels, Johannes and Selmer, Thorsten},
  title     = {Combinatorial assembly of ferredoxin-linked modules in Escherichia coli yields a testing platform for Rnf-complexes},
  series = {Biotechnology and Bioengineering},
  journal   = {Biotechnology and Bioengineering},
  number    = {accepted article},
  publisher = {Wiley},
  address   = {Weinheim},
  doi       = {10.1002/bit.27079},
  pages     = {1 -- 36},
  year      = {2019},
  language  = {en}
}
@article{BreuerPilasGuthmannetal.2019,
  author    = {Breuer, Lars and Pilas, Johanna and Guthmann, Eric and Sch{\"o}ning, Michael Josef and Thoelen, Ronald and Wagner, Torsten},
  title     = {Towards light-addressable flow control: responsive hydrogels with incorporated graphene oxide as laser-driven actuator structures within microfluidic channels},
  series = {Sensor and Actuators B: Chemical},
  volume    = {288},
  journal   = {Sensor and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2019.02.086},
  pages     = {579 -- 585},
  year      = {2019},
  language  = {en}
}
@article{DantismRoehlenWagneretal.2019,
  author    = {Dantism, Shahriar and R{\"o}hlen, Desiree and Wagner, Torsten and Wagner, P. and Sch{\"o}ning, Michael Josef},
  title     = {A LAPS-based differential sensor for parallelized metabolism monitoring of various bacteria},
  series = {Sensors},
  volume    = {19},
  journal   = {Sensors},
  number    = {21},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s19214692},
  pages     = {Artikel 4692},
  year      = {2019},
  abstract  = {Monitoring the cellular metabolism of bacteria in (bio)fermentation processes is crucial to control and steer them, and to prevent undesired disturbances linked to metabolically inactive microorganisms. In this context, cell-based biosensors can play an important role to improve the quality and increase the yield of such processes. This work describes the simultaneous analysis of the metabolic behavior of three different types of bacteria by means of a differential light-addressable potentiometric sensor (LAPS) set-up. The study includes Lactobacillus brevis, Corynebacterium glutamicum, and Escherichia coli, which are often applied in fermentation processes in bioreactors. Differential measurements were carried out to compensate undesirable influences such as sensor signal drift, and pH value variation during the measurements. Furthermore, calibration curves of the cellular metabolism were established as a function of the glucose concentration or cell number variation with all three model microorganisms. In this context, simultaneous (bio)sensing with the multi-organism LAPS-based set-up can open new possibilities for a cost-effective, rapid detection of the extracellular acidification of bacteria on a single sensor chip. It can be applied to evaluate the metabolic response of bacteria populations in a (bio)fermentation process, for instance, in the biogas fermentation process.},
  language  = {en}
}
@article{KarschuckFilipovBollellaetal.2019,
  author    = {Karschuck, T. L. and Filipov, Y. and Bollella, P. and Sch{\"o}ning, Michael Josef and Katz, E.},
  title     = {Not-XOR (NXOR) logic gate based on an enzyme-catalyzed reaction},
  series = {International Journal of Unconventional Computing},
  volume    = {14},
  journal   = {International Journal of Unconventional Computing},
  number    = {3-4},
  publisher = {Old City Publishing},
  address   = {Philadelphia},
  issn      = {1548-7199},
  pages     = {235 -- 242},
  year      = {2019},
  abstract  = {Enzyme-catalyzed reactions have been designed to mimic various Boolean logic gates in the general framework of unconventional biomolecular computing. While some of the logic gates, particularly OR, AND, are easy to realize with biocatalytic reactions and have been reported in numerous publications, some other, like NXOR, are very challenging and have not been realized yet with enzyme reactions. The paper reports on a novel approach to mimicking the NXOR logic gate using the bell-shaped enzyme activity dependent on pH values. Shifting pH from the optimum value to the acidic or basic values by using acid or base inputs (meaning 1,0 and 0,1 inputs) inhibits the enzyme reaction, while keeping the optimum pH (assuming 0,0 and 1,1 input combinations) preserves a high enzyme activity. The challenging part of the present approach is the selection of an enzyme with a well-demonstrated bell-shape activity dependence on the pH value. While many enzymes can satisfy this condition, we selected pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase as this enzyme has the optimum pH center-located on the pH scale allowing the enzyme activity change by the acidic and basic pH shift from the optimum value corresponding to the highest activity. The present NXOR gate is added to the biomolecular "toolbox" as a new example of Boolean logic gates based on enzyme reactions.},
  language  = {en}
}
@article{MennickenPeterKaulenetal.2019,
  author    = {Mennicken, Max and Peter, Sophia Katharina and Kaulen, Corinna and Simon, Ulrich and Karth{\"a}user, Silvia},
  title     = {Controlling the Electronic Contact at the Terpyridine/Metal Interface},
  series = {The Journal of Physical Chemistry C},
  volume    = {123},
  journal   = {The Journal of Physical Chemistry C},
  number    = {35},
  issn      = {1932-7455},
  doi       = {10.1021/acs.jpcc.9b05865},
  pages     = {21367 -- 21375},
  year      = {2019},
  language  = {en}
}
@article{ArreolaKeusgenWagneretal.2019,
  author    = {Arreola, Julio and Keusgen, Michael and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {Combined calorimetric gas- and spore-based biosensor array for online monitoring and sterility assurance of gaseous hydrogen peroxide in aseptic filling machines},
  series = {Biosensors and Bioelectronics},
  volume    = {143},
  journal   = {Biosensors and Bioelectronics},
  number    = {111628},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0956-5663},
  doi       = {10.1016/j.bios.2019.111628},
  year      = {2019},
  language  = {en}
}
@article{JildehKirchnerBaltesetal.2019,
  author    = {Jildeh, Zaid B. and Kirchner, Patrick and Baltes, Klaus and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef},
  title     = {Development of an in-line evaporation unit for the production of gas mixtures containing hydrogen peroxide - numerical modeling and experimental results},
  series = {International Journal of Heat and Mass Transfer},
  volume    = {143},
  journal   = {International Journal of Heat and Mass Transfer},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0017-9310},
  doi       = {10.1016/j.ijheatmasstransfer.2019.118519},
  pages     = {Article number 118519},
  year      = {2019},
  abstract  = {Hydrogen peroxide (H2O2) is a typical surface sterilization agent for packaging materials used in the pharmaceutical, food and beverage industries. We use the finite-elements method to analyze the conceptual design of an in-line thermal evaporation unit to produce a heated gas mixture of air and evaporated H2O2 solution. For the numerical model, the required phase-transition variables of pure H2O2 solution and of the aerosol mixture are acquired from vapor-liquid equilibrium (VLE) diagrams derived from vapor-pressure formulations. This work combines homogeneous single-phase turbulent flow with heat-transfer physics to describe the operation of the evaporation unit. We introduce the apparent heat-capacity concept to approximate the non-isothermal phase-transition process of the H2O2-containing aerosol. Empirical and analytical functions are defined to represent the temperature- and pressure-dependent material properties of the aqueous H2O2 solution, the aerosol and the gas mixture. To validate the numerical model, the simulation results are compared to experimental data on the heating power required to produce the gas mixture. This shows good agreement with the deviations below 10\%. Experimental observations on the formation of deposits due to the evaporation of stabilized H2O2 solution fits the prediction made from simulation results.},
  language  = {en}
}
@article{DantismRoehlenSelmeretal.2019,
  author    = {Dantism, Shahriar and R{\"o}hlen, Desiree and Selmer, Thorsten and Wagner, Torsten and Wagner, Patrick and Sch{\"o}ning, Michael Josef},
  title     = {Quantitative differential monitoring of the metabolic activity of Corynebacterium glutamicum cultures utilizing a light-addressable potentiometric sensor system},
  series = {Biosensors and Bioelectronics},
  volume    = {139},
  journal   = {Biosensors and Bioelectronics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.bios.2019.111332},
  pages     = {Artikel 111332},
  year      = {2019},
  language  = {en}
}
@article{IkenBronderGoretzkietal.2019,
  author    = {Iken, Heiko and Bronder, Thomas and Goretzki, Alexander and Kriesel, Jana and Ahlborn, Kristina and Gerlach, Frank and Vonau, Winfried and Zander, Willi and Schubert, J{\"u}rgen and Sch{\"o}ning, Michael Josef},
  title     = {Development of a Combined pH- and Redox-Sensitive Bi-Electrode Glass Thin-Film Sensor},
  series = {physica status solidi a : applications and materials sciences},
  volume    = {216},
  journal   = {physica status solidi a : applications and materials sciences},
  number    = {12},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1862-6319},
  doi       = {10.1002/pssa.201900114},
  pages     = {1 -- 8},
  year      = {2019},
  language  = {en}
}
@article{OezsoyluKizildagSchoeningetal.2019,
  author    = {{\"O}zsoylu, Dua and Kizildag, Sefa and Sch{\"o}ning, Michael Josef and Wagner, Torsten},
  title     = {Effect of plasma treatment on the sensor properties of a light-addressable potentiometric sensor (LAPS)},
  series = {physica status solidi a : applications and materials sciences},
  volume    = {216},
  journal   = {physica status solidi a : applications and materials sciences},
  number    = {20},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1862-6319},
  doi       = {10.1002/pssa.201900259},
  pages     = {8 Seiten},
  year      = {2019},
  abstract  = {A light-addressable potentiometric sensor (LAPS) is a field-effect-based (bio-) chemical sensor, in which a desired sensing area on the sensor surface can be defined by illumination. Light addressability can be used to visualize the concentration and spatial distribution of the target molecules, e.g., H+ ions. This unique feature has great potential for the label-free imaging of the metabolic activity of living organisms. The cultivation of those organisms needs specially tailored surface properties of the sensor. O2 plasma treatment is an attractive and promising tool for rapid surface engineering. However, the potential impacts of the technique are carefully investigated for the sensors that suffer from plasma-induced damage. Herein, a LAPS with a Ta2O5 pH-sensitive surface is successfully patterned by plasma treatment, and its effects are investigated by contact angle and scanning LAPS measurements. The plasma duration of 30 s (30 W) is found to be the threshold value, where excessive wettability begins. Furthermore, this treatment approach causes moderate plasma-induced damage, which can be reduced by thermal annealing (10 min at 300 °C). These findings provide a useful guideline to support future studies, where the LAPS surface is desired to be more hydrophilic by O2 plasma treatment.},
  language  = {en}
}
@article{PilasSelmerKeusgenetal.2019,
  author    = {Pilas, Johanna and Selmer, Thorsten and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Screen-printed carbon electrodes modified with graphene oxide for the design of a reagent-free NAD+-dependent biosensor array},
  series = {Analytical Chemistry},
  volume    = {91},
  journal   = {Analytical Chemistry},
  number    = {23},
  publisher = {ACS Publications},
  address   = {Washington},
  doi       = {10.1021/acs.analchem.9b04481},
  pages     = {15293 -- 15299},
  year      = {2019},
  language  = {en}
}
@article{AchtsnichtPourshahidiOffenhaeusseretal.2019,
  author    = {Achtsnicht, Stefan and Pourshahidi, Ali Mohammad and Offenh{\"a}usser, Andreas and Krause, Hans-Joachim},
  title     = {Multiplex detection of different magnetic beads using frequency scanning in magnetic frequency mixing technique},
  series = {Sensors},
  volume    = {19},
  journal   = {Sensors},
  number    = {11},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s19112599},
  pages     = {13 Seiten},
  year      = {2019},
  abstract  = {In modern bioanalytical methods, it is often desired to detect several targets in one sample within one measurement. Immunological methods including those that use superparamagnetic beads are an important group of techniques for these applications. The goal of this work is to investigate the feasibility of simultaneously detecting different superparamagnetic beads acting as markers using the magnetic frequency mixing technique. The frequency of the magnetic excitation field is scanned while the lower driving frequency is kept constant. Due to the particles' nonlinear magnetization, mixing frequencies are generated. To record their amplitude and phase information, a direct digitization of the pickup-coil's signal with subsequent Fast Fourier Transformation is performed. By synchronizing both magnetic beads using frequency scanning in magnetic frequency mixing technique magnetic fields, a stable phase information is gained. In this research, it is shown that the amplitude of the dominant mixing component is proportional to the amount of superparamagnetic beads inside a sample. Additionally, it is shown that the phase does not show this behaviour. Excitation frequency scans of different bead types were performed, showing different phases, without correlation to their diverse amplitudes. Two commercially available beads were selected and a determination of their amount in a mixture is performed as a demonstration for multiplex measurements.},
  language  = {en}
}
@article{AchtsnichtToedterNiehuesetal.2019,
  author    = {Achtsnicht, Stefan and T{\"o}dter, Julia and Niehues, Julia and Tel{\"o}ken, Matthias and Offenh{\"a}usser, Andreas and Krause, Hans-Joachim and Schr{\"o}per, Florian},
  title     = {3D printed modular immunofiltration columns for frequency mixing-based multiplex magnetic immunodetection},
  series = {Sensors},
  volume    = {19},
  journal   = {Sensors},
  number    = {1},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s19010148},
  pages     = {15 Seiten},
  year      = {2019},
  abstract  = {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.},
  language  = {en}
}
@article{AchtsnichtSchoenenbornOffenhaeusseretal.2019,
  author    = {Achtsnicht, Stefan and Sch{\"o}nenborn, Kristina and Offenh{\"a}usser, Andreas and Krause, Hans-Joachim},
  title     = {Measurement of the magnetophoretic velocity of different superparamagnetic beads},
  series = {Journal of Magnetism and Magnetic Materials},
  volume    = {477},
  journal   = {Journal of Magnetism and Magnetic Materials},
  number    = {1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0304-8853},
  doi       = {10.1016/j.jmmm.2018.10.066},
  pages     = {244 -- 248},
  year      = {2019},
  abstract  = {The movement of magnetic beads due to a magnetic field gradient is of great interest in different application fields. In this report we present a technique based on a magnetic tweezers setup to measure the velocity factor of magnetically actuated individual superparamagnetic beads in a fluidic environment. Several beads can be tracked simultaneously in order to gain and improve statistics. Furthermore we show our results for different beads with hydrodynamic diameters between 200 and 1000 nm from diverse manufacturers. These measurement data can, for example, be used to determine design parameters for a magnetic separation system, like maximum flow rate and minimum separation time, or to select suitable beads for fixed experimental requirements.},
  language  = {en}
}
@article{AchtsnichtNeuendorfFassbenderetal.2019,
  author    = {Achtsnicht, Stefan and Neuendorf, Christian and Faßbender, Tobias and N{\"o}lke, Greta and Offenh{\"a}usser, Andreas and Krause, Hans-Joachim and Schr{\"o}per, Florian},
  title     = {Sensitive and rapid detection of cholera toxin subunit B using magnetic frequency mixing detection},
  series = {Plos One},
  volume    = {14},
  journal   = {Plos One},
  number    = {7},
  publisher = {Plos},
  address   = {San Francisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0219356},
  pages     = {e0219356},
  year      = {2019},
  abstract  = {Cholera is a life-threatening disease caused by the cholera toxin (CT) as produced by some Vibrio cholerae serogroups. In this research we present a method which directly detects the toxin's B subunit (CTB) in drinking water. For this purpose we performed a magnetic sandwich immunoassay inside a 3D immunofiltration column. We used two different commercially available antibodies to capture CTB and for binding to superparamagnetic beads. ELISA experiments were performed to select the antibody combination. The beads act as labels for the magnetic frequency mixing detection technique. We show that the limit of detection depends on the type of magnetic beads. A nonlinear Hill curve was fitted to the calibration measurements by means of a custom-written python software. We achieved a sensitive and rapid detection of CTB within a broad concentration range from 0.2 ng/ml to more than 700 ng/ml.},
  language  = {en}
}
@article{FigueroaMirandaFengShiuetal.2018,
  author    = {Figueroa-Miranda, Gabriela and Feng, Lingyan and Shiu, Simon Chi-Chin and Dirkzwager, Roderick Marshall and Cheung, Yee-Wai and Tanner, Julian Alexander and Sch{\"o}ning, Michael Josef and Offenh{\"a}usser, Andreas and Mayer, Dirk},
  title     = {Aptamer-based electrochemical biosensor for highly sensitive and selective malaria detection with adjustable dynamic response range and reusability},
  series = {Sensor and Actuators B: Chemical},
  volume    = {255},
  journal   = {Sensor and Actuators B: Chemical},
  number    = {P1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2017.07.117},
  pages     = {235 -- 243},
  year      = {2018},
  abstract  = {Malaria infection remains a significant risk for much of the population of tropical and subtropical areas, particularly in developing countries. Therefore, it is of high importance to develop sensitive, accurate and inexpensive malaria diagnosis tests. Here, we present a novel aptamer-based electrochemical biosensor (aptasensor) for malaria detection by impedance spectroscopy, through the specific recognition between a highly discriminatory DNA aptamer and its target Plasmodium falciparum lactate dehydrogenase (PfLDH). Interestingly, due to the isoelectric point (pI) of PfLDH, the aptasensor response showed an adjustable detection range based on the different protein net-charge at variable pH environments. The specific aptamer recognition allows sensitive protein detection with an expanded detection range and a low detection limit, as well as a high specificity for PfLDH compared to analogous proteins. The specific feasibility of the aptasensor is further demonstrated by detection of the target PfLDH in human serum. Furthermore, the aptasensor can be easily regenerated and thus applied for multiple usages. The robustness, sensitivity, and reusability of the presented aptasensor make it a promising candidate for point-of-care diagnostic systems.},
  language  = {en}
}
@article{MolinnusHardtSiegertetal.2018,
  author    = {Molinnus, Denise and Hardt, Gabriel and Siegert, Petra and Willenberg, Holger S. and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Detection of Adrenaline in Blood Plasma as Biomarker for Adrenal Venous Sampling},
  series = {Electroanalysis},
  volume    = {30},
  journal   = {Electroanalysis},
  number    = {5},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1521-4109},
  doi       = {10.1002/elan.201800026},
  pages     = {937 -- 942},
  year      = {2018},
  abstract  = {An amperometric bi-enzyme biosensor based on substrate recycling principle for the amplification of the sensor signal has been developed for the detection of adrenaline in blood. Adrenaline can be used as biomarker verifying successful adrenal venous sampling procedure. The adrenaline biosensor has been realized via modification of a galvanic oxygen sensor with a bi-enzyme membrane combining a genetically modified laccase and a pyrroloquinoline quinone-dependent glucose dehydrogenase. The measurement conditions such as pH value and temperature were optimized to enhance the sensor performance. A high sensitivity and a low detection limit of about 0.5-1 nM adrenaline have been achieved in phosphate buffer at pH 7.4, relevant for measurements in blood samples. The sensitivity of the biosensor to other catecholamines such as noradrenaline, dopamine and dobutamine has been studied. Finally, the sensor has been successfully applied for the detection of adrenaline in human blood plasma.},
  language  = {en}
}
@article{OberlaenderMayerGreeffetal.2018,
  author    = {Oberl{\"a}nder, Jan and Mayer, Marlena and Greeff, Anton and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Spore-based biosensor to monitor the microbicidal efficacy of gaseous hydrogen peroxide sterilization processes},
  series = {Biosensors and Bioelectronics},
  volume    = {104},
  journal   = {Biosensors and Bioelectronics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0956-5663},
  doi       = {10.1016/j.bios.2017.12.045},
  pages     = {87 -- 94},
  year      = {2018},
  abstract  = {In this work, a spore-based biosensor is evaluated to monitor the microbicidal efficacy of sterilization processes applying gaseous hydrogen peroxide (H2O2). The sensor is based on interdigitated electrode structures (IDEs) that have been fabricated by means of thin-film technologies. Impedimetric measurements are applied to study the effect of sterilization process on spores of Bacillus atrophaeus. This resilient microorganism is commonly used in industry to proof the sterilization efficiency. The sensor measurements are accompanied by conventional microbiological challenge tests, as well as morphological characterizations with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The sensor measurements are correlated with the microbiological test routines. In both methods, namely the sensor-based and microbiological one, a tailing effect has been observed. The results are evaluated and discussed in a three-dimensional calibration plot demonstrating the sensor's suitability to enable a rapid process decision in terms of a successfully performed sterilization.},
  language  = {en}
}
@article{MolinnusMuschallikGonzalezetal.2018,
  author    = {Molinnus, Denise and Muschallik, Lukas and Gonzalez, Laura Osorio and Bongaerts, Johannes and Wagner, Torsten and Selmer, Thorsten and Siegert, Petra and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Development and characterization of a field-effect biosensor for the detection of acetoin},
  series = {Biosensors and Bioelectronics},
  volume    = {115},
  journal   = {Biosensors and Bioelectronics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.bios.2018.05.023},
  pages     = {1 -- 6},
  year      = {2018},
  abstract  = {A capacitive electrolyte-insulator-semiconductor (EIS) field-effect biosensor for acetoin detection has been presented for the first time. The EIS sensor consists of a layer structure of Al/p-Si/SiO₂/Ta₂O₅/enzyme acetoin reductase. The enzyme, also referred to as butane-2,3-diol dehydrogenase from B. clausii DSM 8716T, has been recently characterized. The enzyme catalyzes the (R)-specific reduction of racemic acetoin to (R,R)- and meso-butane-2,3-diol, respectively. Two different enzyme immobilization strategies (cross-linking by using glutaraldehyde and adsorption) have been studied. Typical biosensor parameters such as optimal pH working range, sensitivity, hysteresis, linear concentration range and long-term stability have been examined by means of constant-capacitance (ConCap) mode measurements. Furthermore, preliminary experiments have been successfully carried out for the detection of acetoin in diluted white wine samples.},
  language  = {en}
}
@article{PilasYaziciSelmeretal.2018,
  author    = {Pilas, Johanna and Yazici, Y. and Selmer, Thorsten and Keusgen, M. and Sch{\"o}ning, Michael Josef},
  title     = {Application of a portable multi-analyte biosensor for organic acid determination in silage},
  series = {Sensors},
  volume    = {18},
  journal   = {Sensors},
  number    = {5},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s18051470},
  pages     = {12 Seiten},
  year      = {2018},
  abstract  = {Multi-analyte biosensors may offer the opportunity to perform cost-effective and rapid analysis with reduced sample volume, as compared to electrochemical biosensing of each analyte individually. This work describes the development of an enzyme-based biosensor system for multi-parametric determination of four different organic acids. The biosensor array comprises five working electrodes for simultaneous sensing of ethanol, formate, d-lactate, and l-lactate, and an integrated counter electrode. Storage stability of the biosensor was evaluated under different conditions (stored at +4 °C in buffer solution and dry at -21 °C, +4 °C, and room temperature) over a period of 140 days. After repeated and regular application, the individual sensing electrodes exhibited the best stability when stored at -21 °C. Furthermore, measurements in silage samples (maize and sugarcane silage) were conducted with the portable biosensor system. Comparison with a conventional photometric technique demonstrated successful employment for rapid monitoring of complex media.},
  language  = {en}
}
@article{DantismRoehlenWagneretal.2018,
  author    = {Dantism, Shahriar and R{\"o}hlen, Desiree and Wagner, Torsten and Wagner, Patrick and Sch{\"o}ning, Michael Josef},
  title     = {Optimization of Cell-Based Multi-Chamber LAPS Measurements Utilizing FPGA-Controlled Laser-Diode Modules},
  series = {physica status solidi a : applications and materials sciences},
  volume    = {215},
  journal   = {physica status solidi a : applications and materials sciences},
  number    = {15},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1862-6319},
  doi       = {10.1002/pssa.201800058},
  pages     = {Article number 1800058},
  year      = {2018},
  abstract  = {A light-addressable potentiometric sensor (LAPS) is a field-effect-based potentiometric device, which detects concentration changes of an analyte solution on the sensor surface in a spatially resolved way. It uses a light source to generate electron-hole pairs inside the semiconductor, which are separated in the depletion region due to an applied bias voltage across the sensor structure and hence, a surface-potential-dependent photocurrent can be read out. However, depending on the beam angle of the light source, scattering effects can occur, which influence the recorded signal in LAPS-based differential measurements. To solve this problem, a novel illumination unit based on a field programmable gate array (FPGA) consisting of 16 small-sized tunable infrared laser-diode modules (LDMs) is developed. Due to the improved focus of the LDMs with a beam angle of only 2 mrad, undesirable scattering effects are minimized. Escherichia coli (E. coli) K12 bacteria are used as a test microorganism to study the extracellular acidification on the sensor surface. Furthermore, a salt bridge chamber is built up and integrated with the LAPS system enabling multi-chamber differential measurements with a single Ag/AgCl reference electrode.},
  language  = {en}
}
@article{MolinnusHardtKaeveretal.2018,
  author    = {Molinnus, Denise and Hardt, G. and K{\"a}ver, L. and Willenberg, H.S. and Kr{\"o}ger, J.-C. and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Chip-based biosensor for the detection of low adrenaline concentrations to support adrenal venous sampling},
  series = {Sensor and Actuators B: Chemical},
  volume    = {272},
  journal   = {Sensor and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2018.05.136},
  pages     = {21 -- 27},
  year      = {2018},
  abstract  = {A chip-based amperometric biosensor referring on using the bioelectrocatalytical amplification principle for the detection of low adrenaline concentrations is presented. The adrenaline biosensor has been prepared by modification of a platinum thin-film electrode with an enzyme membrane containing the pyrroloquinoline quinone-dependent glucose dehydrogenase and glutaraldehyde. Measuring conditions such as temperature, pH value, and glucose concentration have been optimized to achieve a high sensitivity and a low detection limit of about 1 nM adrenaline measured in phosphate buffer at neutral pH value. The response of the biosensor to different catecholamines has also been proven. Long-term stability of the adrenaline biosensor has been studied over 10 days. In addition, the biosensor has been successfully applied for adrenaline detection in human blood plasma for future biomedical applications. Furthermore, preliminary experiments have been carried to detect the adrenaline-concentration difference measured in peripheral blood and adrenal venous blood, representing the adrenal vein sampling procedure of a physician.},
  language  = {en}
}
@article{WeldenSchejaSchoeningetal.2018,
  author    = {Welden, Rene and Scheja, Sabrina and Sch{\"o}ning, Michael Josef and Wagner, Patrick and Wagner, Torsten},
  title     = {Electrochemical Evaluation of Light-Addressable Electrodes Based on TiO2 for the Integration in Lab-on-Chip Systems},
  series = {physica status solidi a : applications and materials sciences},
  volume    = {215},
  journal   = {physica status solidi a : applications and materials sciences},
  number    = {15},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1862-6319},
  doi       = {10.1002/pssa.201800150},
  pages     = {Article number 1800150},
  year      = {2018},
  abstract  = {In lab-on-chip systems, electrodes are important for the manipulation (e.g., cell stimulation, electrolysis) within such systems. An alternative to commonly used electrode structures can be a light-addressable electrode. Here, due to the photoelectric effect, the conducting area can be adjusted by modification of the illumination area which enables a flexible control of the electrode. In this work, titanium dioxide based light-addressable electrodes are fabricated by a sol-gel technique and a spin-coating process, to deposit a thin film on a fluorine-doped tin oxide glass. To characterize the fabricated electrodes, the thickness, and morphological structure are measured by a profilometer and a scanning electron microscope. For the electrochemical behavior, the dark current and the photocurrent are determined for various film thicknesses. For the spatial resolution behavior, the dependency of the photocurrent while changing the area of the illuminated area is studied. Furthermore, the addressing of single fluid compartments in a three-chamber system, which is added to the electrode, is demonstrated.},
  language  = {en}
}
@incollection{KochPoghossianWegeetal.2018,
  author    = {Koch, Claudia and Poghossian, Arshak and Wege, Christina and Sch{\"o}ning, Michael Josef},
  title     = {TMV-Based Adapter Templates for Enhanced Enzyme Loading in Biosensor Applications},
  series = {Virus-Derived Nanoparticles for Advanced Technologies},
  booktitle = {Virus-Derived Nanoparticles for Advanced Technologies},
  editor    = {Wege, Christina},
  publisher = {Humana Press},
  address   = {New York, NY},
  isbn      = {978-1-4939-7808-3},
  doi       = {10.1007/978-1-4939-7808-3},
  pages     = {553 -- 568},
  year      = {2018},
  abstract  = {Nanotubular tobacco mosaic virus (TMV) particles and RNA-free lower-order coat protein (CP) aggregates have been employed as enzyme carriers in different diagnostic layouts and compared for their influence on biosensor performance. In the following, we describe a label-free electrochemical biosensor for improved glucose detection by use of TMV adapters and the enzyme glucose oxidase (GOD). A specific and efficient immobilization of streptavidin-conjugated GOD ([SA]-GOD) complexes on biotinylated TMV nanotubes or CP aggregates was achieved via bioaffinity binding. Glucose sensors with adsorptively immobilized [SA]-GOD, and with [SA]-GOD cross-linked with glutardialdehyde, respectively, were tested in parallel on the same sensor chip. Comparison of these sensors revealed that TMV adapters enhanced the amperometric glucose detection remarkably, conveying highest sensitivity, an extended linear detection range and fastest response times. These results underline a great potential of an integration of virus/biomolecule hybrids with electronic transducers for applications in biosensorics and biochips. Here, we describe the fabrication and use of amperometric sensor chips combining an array of circular Pt electrodes, their loading with GOD-modified TMV nanotubes (and other GOD immobilization methods), and the subsequent investigations of the sensor performance.},
  language  = {en}
}
@article{BronderJessingPoghossianetal.2018,
  author    = {Bronder, Thomas and Jessing, Max P. and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Detection of PCR-Amplified Tuberculosis DNA Fragments with Polyelectrolyte-Modified Field-Effect Sensors},
  series = {Analytical Chemistry},
  volume    = {90},
  journal   = {Analytical Chemistry},
  number    = {12},
  publisher = {ACS Publications},
  address   = {Washington, DC},
  issn      = {0003-2700},
  doi       = {10.1021/acs.analchem.8b01807},
  pages     = {7747 -- 7753},
  year      = {2018},
  abstract  = {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.},
  language  = {en}
}
@article{JildehOberlaenderKirchneretal.2018,
  author    = {Jildeh, Zaid B. and Oberl{\"a}nder, Jan and Kirchner, Patrick and Keusgen, Michael and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef},
  title     = {Experimental and Numerical Analyzes of a Sensor Based on Interdigitated Electrodes for Studying Microbiological Alterations},
  series = {physica status solidi (a): applications and materials science},
  volume    = {215},
  journal   = {physica status solidi (a): applications and materials science},
  number    = {15},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1862-6319},
  doi       = {10.1002/pssa.201700920},
  pages     = {Artikel 1700920},
  year      = {2018},
  abstract  = {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.},
  language  = {en}
}
@article{JildehOberlaenderKirchneretal.2018,
  author    = {Jildeh, Zaid B. and Oberl{\"a}nder, Jan and Kirchner, Patrick and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef},
  title     = {Thermocatalytic Behavior of Manganese (IV) Oxide as Nanoporous Material on the Dissociation of a Gas Mixture Containing Hydrogen Peroxide},
  series = {Nanomaterials},
  volume    = {8},
  journal   = {Nanomaterials},
  number    = {4},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2079-4991},
  doi       = {10.3390/nano8040262},
  pages     = {Artikel 262},
  year      = {2018},
  abstract  = {In this article, we present an overview on the thermocatalytic reaction of hydrogen peroxide (H₂O₂) gas on a manganese (IV) oxide (MnO₂) catalytic structure. The principle of operation and manufacturing techniques are introduced for a calorimetric H₂O₂ gas sensor based on porous MnO₂. Results from surface analyses by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) of the catalytic material provide indication of the H₂O₂ dissociation reaction schemes. The correlation between theory and the experiments is documented in numerical models of the catalytic reaction. The aim of the numerical models is to provide further information on the reaction kinetics and performance enhancement of the porous MnO₂ catalyst.},
  language  = {en}
}
@article{AboulnagaZouSelmeretal.2018,
  author    = {Aboulnaga, E. A. and Zou, H. and Selmer, Thorsten and Xian, M.},
  title     = {Development of a plasmid-based, tunable, tolC-derived expression system for application in Cupriavidus necator H16},
  series = {Journal of Biotechnology},
  volume    = {274},
  journal   = {Journal of Biotechnology},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0168-1656},
  doi       = {10.1016/j.jbiotec.2018.03.007},
  pages     = {15 -- 27},
  year      = {2018},
  abstract  = {Cupriavidus necator H16 gains increasing attention in microbial research and biotechnological application due to its diverse metabolic features. Here we present a tightly controlled gene expression system for C. necator including the pBBR1-vector that contains hybrid promoters originating from C. necator native tolC-promoter in combination with a synthetic tetO-operator. The expression of the reporter gene from these plasmids relies on the addition of the exogenous inducer doxycycline (dc). The novel expression system offers a combination of advantageous features as; (i) high and dose-dependent recombinant protein production, (ii) tight control with a high dynamic range (On/Off ratio), which makes it applicable for harmful pathways or for toxic protein production, (iii) comparable cheap inducer (doxycycline, dc), (iv) effective at low inducer concentration, that makes it useful for large scale application, (v) rapid, diffusion controlled induction, and (vi) the inducer does not interfere within the cell metabolism. As applications of the expression system in C. necator H16, the growth ability on glycerol was enhanced by constitutively expressing the E. coli glpk gene-encoding for glycerol kinase. Likewise, we used the system to overcome the expression toxicity of mevalonate pathway in C. necator H16. With this system, the mevalonate-genes were successfully introduced in the host and the recombinant strains could produce about 200 mg/l mevalonate.},
  language  = {en}
}
@article{KochPoghossianSchoeningetal.2018,
  author    = {Koch, Claudia and Poghossian, Arshak and Sch{\"o}ning, Michael Josef and Wege, Christian},
  title     = {Penicillin Detection by Tobacco Mosaic Virus-Assisted Colorimetric Biosensors},
  series = {Nanotheranostics},
  volume    = {2},
  journal   = {Nanotheranostics},
  number    = {2},
  publisher = {Ivyspring},
  address   = {Sydney},
  issn      = {2206-7418},
  doi       = {10.7150/ntno.22114},
  pages     = {184 -- 196},
  year      = {2018},
  abstract  = {The presentation of enzymes on viral scaffolds has beneficial effects such as an increased enzyme loading and a prolonged reusability in comparison to conventional immobilization platforms. Here, we used modified tobacco mosaic virus (TMV) nanorods as enzyme carriers in penicillin G detection for the first time. Penicillinase enzymes were conjugated with streptavidin and coupled to TMV rods by use of a bifunctional biotin-linker. Penicillinase-decorated TMV particles were characterized extensively in halochromic dye-based biosensing. Acidometric analyte detection was performed with bromcresol purple as pH indicator and spectrophotometry. The TMV-assisted sensors exhibited increased enzyme loading and strongly improved reusability, and higher analysis rates compared to layouts without viral adapters. They extended the half-life of the sensors from 4 - 6 days to 5 weeks and thus allowed an at least 8-fold longer use of the sensors. Using a commercial budget-priced penicillinase preparation, a detection limit of 100 µM penicillin was obtained. Initial experiments also indicate that the system may be transferred to label-free detection layouts.},
  language  = {en}
}
@article{VahidpourOberlaenderSchoening2018,
  author    = {Vahidpour, Farnoosh and Oberl{\"a}nder, Jan and Sch{\"o}ning, Michael Josef},
  title     = {Flexible Calorimetric Gas Sensors for Detection of a Broad Concentration Range of Gaseous Hydrogen Peroxide: A Step Forward to Online Monitoring of Food-Package Sterilization Processes},
  series = {Phys. Status Solidi A},
  volume    = {215},
  journal   = {Phys. Status Solidi A},
  number    = {15},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  doi       = {10.1002/pssa.201800044},
  pages     = {Artikel 1800044},
  year      = {2018},
  abstract  = {In this study, flexible calorimetric gas sensors are developed for specificdetection of gaseous hydrogen peroxide (H₂O₂) over a wide concentrationrange, which is used in sterilization processes for aseptic packaging industry.The flexibility of these sensors is an advantage for identifying the chemical components of the sterilant on the corners of the food boxes, so-called "coldspots", as critical locations in aseptic packaging, which are of great importance. These sensors are fabricated on flexible polyimide films by means of thin-film technique. Thin layers of titanium and platinum have been deposited on polyimide to define the conductive structures of the sensors. To detect the high-temperature evaporated H₂O₂, a differential temperature set-up is proposed. The sensors are evaluated in a laboratory-scaled sterilizationsystem to simulate the sterilization process. The concentration range of the evaporated H₂O₂ from 0 to 7.7\% v/v was defined and the sensors have successfully detected high as well as low H₂O₂ concentrations with a sensitivity of 5.04 °C/\% v/v. The characterizations of the sensors confirm their precise fabrication, high sensitivity and the novelty of low H₂O₂ concentration detections for future inline monitoring of food-package sterilization.},
  language  = {en}
}
@article{PoghossianJablonskiKochetal.2018,
  author    = {Poghossian, Arshak and Jablonski, Melanie and Koch, Claudia and Bronder, Thomas and Rolka, David and Wege, Christina and Sch{\"o}ning, Michael Josef},
  title     = {Field-effect biosensor using virus particles as scaffolds for enzyme immobilization},
  series = {Biosensors and Bioelectronics},
  volume    = {110},
  journal   = {Biosensors and Bioelectronics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0956-5663},
  doi       = {10.1016/j.bios.2018.03.036},
  pages     = {168 -- 174},
  year      = {2018},
  abstract  = {A field-effect biosensor employing tobacco mosaic virus (TMV) particles as scaffolds for enzyme immobilization is presented. Nanotubular TMV scaffolds allow a dense immobilization of precisely positioned enzymes with retained activity. To demonstrate feasibility of this new strategy, a penicillin sensor has been developed by coupling a penicillinase with virus particles as a model system. The developed field-effect penicillin biosensor consists of an Al-p-Si-SiO₂-Ta₂O₅-TMV structure and has been electrochemically characterized in buffer solutions containing different concentrations of penicillin G. In addition, the morphology of the biosensor surface with virus particles was characterized by scanning electron microscopy and atomic force microscopy methods. The sensors possessed a high penicillin sensitivity of ~ 92 mV/dec in a nearly-linear range from 0.1 mM to 10 mM, and a low detection limit of about 50 µM. The long-term stability of the penicillin biosensor was periodically tested over a time period of about one year without any significant loss of sensitivity. The biosensor has also been successfully applied for penicillin detection in bovine milk samples.},
  language  = {en}
}
@article{MiyamotoSekiSutoetal.2018,
  author    = {Miyamoto, Koichiro and Seki, Kosuke and Suto, Takeyuki and Werner, Frederik and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Improved spatial resolution of the chemical imaging sensor with a hybrid illumination that suppresses lateral diffusion of photocarriers},
  series = {Sensor and Actuators B: Chemical},
  volume    = {273},
  journal   = {Sensor and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2018.07.016},
  pages     = {1328 -- 1333},
  year      = {2018},
  abstract  = {The chemical imaging sensor is a semiconductor-based chemical sensor capable of visualizing pH and ion distributions. The spatial resolution depends on the lateral diffusion of photocarriers generated by illumination of the semiconductor substrate. In this study, two types of optical setups, one based on a bundle of optical fibers and the other based on a binocular tube head, were developed to project a hybrid illumination of a modulated light beam and a ring-shaped constant illumination onto the sensor plate. An improved spatial resolution was realized by the ring-shaped constant illumination, which suppressed lateral diffusion of photocarriers by enhanced recombination due to the increased carrier concentration.},
  language  = {en}
}
@article{RoehlenPilasDahmenetal.2018,
  author    = {R{\"o}hlen, Desiree and Pilas, Johanna and Dahmen, Markus and Keusgen, Michael and Selmer, Thorsten and Sch{\"o}ning, Michael Josef},
  title     = {Toward a Hybrid Biosensor System for Analysis of Organic and Volatile Fatty Acids in Fermentation Processes},
  series = {Frontiers in Chemistry},
  journal   = {Frontiers in Chemistry},
  number    = {6},
  publisher = {Frontiers},
  address   = {Lausanne},
  doi       = {10.3389/fchem.2018.00284},
  pages     = {Artikel 284},
  year      = {2018},
  abstract  = {Monitoring of organic acids (OA) and volatile fatty acids (VFA) is crucial for the control of anaerobic digestion. In case of unstable process conditions, an accumulation of these intermediates occurs. In the present work, two different enzyme-based biosensor arrays are combined and presented for facile electrochemical determination of several process-relevant analytes. Each biosensor utilizes a platinum sensor chip (14 × 14 mm²) with five individual working electrodes. The OA biosensor enables simultaneous measurement of ethanol, formate, d- and l-lactate, based on a bi-enzymatic detection principle. The second VFA biosensor provides an amperometric platform for quantification of acetate and propionate, mediated by oxidation of hydrogen peroxide. The cross-sensitivity of both biosensors toward potential interferents, typically present in fermentation samples, was investigated. The potential for practical application in complex media was successfully demonstrated in spiked sludge samples collected from three different biogas plants. Thereby, the results obtained by both of the biosensors were in good agreement to the applied reference measurements by photometry and gas chromatography, respectively. The proposed hybrid biosensor system was also used for long-term monitoring of a lab-scale biogas reactor (0.01 m³) for a period of 2 months. In combination with typically monitored parameters, such as gas quality, pH and FOS/TAC (volatile organic acids/total anorganic carbonate), the amperometric measurements of OA and VFA concentration could enhance the understanding of ongoing fermentation processes.},
  language  = {en}
}
@article{RodriguesMoraisNordietal.2018,
  author    = {Rodrigues, Raul T. and Morais, Paulo V. and Nordi, Cristina S. F. and Sch{\"o}ning, Michael Josef and Siqueira Jr., Jos{\´e} R. and Caseli, Luciano},
  title     = {Carbon Nanotubes and Algal Polysaccharides To Enhance the Enzymatic Properties of Urease in Lipid Langmuir-Blodgett Films},
  series = {Langmuir},
  volume    = {34},
  journal   = {Langmuir},
  number    = {9},
  publisher = {ACS Publications},
  address   = {Washington, DC},
  issn      = {1520-5827},
  doi       = {10.1021/acs.langmuir.7b04317},
  pages     = {3082 -- 3093},
  year      = {2018},
  abstract  = {Algal polysaccharides (extracellular polysaccharides) and carbon nanotubes (CNTs) were adsorbed on dioctadecyldimethylammonium bromide Langmuir monolayers to serve as a matrix for the incorporation of urease. The physicochemical properties of the supramolecular system as a monolayer at the air-water interface were investigated by surface pressure-area isotherms, surface potential-area isotherms, interfacial shear rheology, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to hydrophilic solid supports, quartz, mica, or capacitive electrolyte-insulator-semiconductor (EIS) devices, through the Langmuir-Blodgett (LB) technique, forming mixed films, which were investigated by quartz crystal microbalance, fluorescence spectroscopy, and field emission gun scanning electron microscopy. The enzyme activity was studied with UV-vis spectroscopy, and the feasibility of the thin film as a urea sensor was essayed in an EIS sensor device. The presence of CNT in the enzyme-lipid LB film not only tuned the catalytic activity of urease but also helped to conserve its enzyme activity. Viability as a urease 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 are related to the synergism between the compounds on the active layer, leading to a surface morphology that allowed fast analyte diffusion owing to an adequate molecular accommodation, which also preserved the urease activity. This work demonstrates the feasibility of employing LB films composed of lipids, CNT, algal polysaccharides, and enzymes as EIS devices for biosensing applications.},
  language  = {en}
}
@book{SchoeningPoghossian2018,
  author    = {Sch{\"o}ning, Michael Josef and Poghossian, Arshak},
  title     = {Label-free biosensing: advanced materials, devices and applications},
  publisher = {Springer},
  address   = {Cham},
  isbn      = {978-3-319-75219-8},
  pages     = {xii, 480 Seiten ; Illustrationen, Diagramme},
  year      = {2018},
  language  = {en}
}
@incollection{YoshinobuKrauseMiyamotoetal.2018,
  author    = {Yoshinobu, Tatsuo and Krause, Steffi and Miyamoto, Ko-ichiro and Werner, Frederik and Poghossian, Arshak and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {(Bio-)chemical Sensing and Imaging by LAPS and SPIM},
  series = {Label-free biosensing: advanced materials, devices and applications},
  booktitle = {Label-free biosensing: advanced materials, devices and applications},
  publisher = {Springer},
  address   = {Cham},
  isbn      = {978-3-319-75219-8},
  pages     = {103 -- 132},
  year      = {2018},
  abstract  = {The light-addressable potentiometric sensor (LAPS) and scanning photo-induced impedance microscopy (SPIM) are two closely related methods to visualise the distributions of chemical species and impedance, respectively, at the interface between the sensing surface and the sample solution. They both have the same field-effect structure based on a semiconductor, which allows spatially resolved and label-free measurement of chemical species and impedance in the form of a photocurrent signal generated by a scanning light beam. In this article, the principles and various operation modes of LAPS and SPIM, functionalisation of the sensing surface for measuring various species, LAPS-based chemical imaging and high-resolution sensors based on silicon-on-sapphire substrates are described and discussed, focusing on their technical details and prospective applications.},
  language  = {en}
}