@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}
}
@article{PoghossianJablonskiMolinnusetal.2020,
  author    = {Poghossian, Arshak and Jablonski, Melanie and Molinnus, Denise and Wege, Christina and Sch{\"o}ning, Michael Josef},
  title     = {Field-Effect Sensors for Virus Detection: From Ebola to SARS-CoV-2 and Plant Viral Enhancers},
  series = {Frontiers in Plant Science},
  volume    = {11},
  journal   = {Frontiers in Plant Science},
  number    = {Article 598103},
  publisher = {Frontiers},
  address   = {Lausanne},
  doi       = {10.3389/fpls.2020.598103},
  pages     = {1 -- 14},
  year      = {2020},
  abstract  = {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.},
  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{PoghossianSchoening2021,
  author    = {Poghossian, Arshak and Sch{\"o}ning, Michael Josef},
  title     = {Recent progress in silicon-based biologically sensitive field-effect devices},
  series = {Current Opinion in Electrochemistry},
  journal   = {Current Opinion in Electrochemistry},
  number    = {Article number: 100811},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {2451-9103},
  doi       = {10.1016/j.coelec.2021.100811},
  year      = {2021},
  abstract  = {Biologically sensitive field-effect devices (BioFEDs) advantageously combine the electronic field-effect functionality with the (bio)chemical receptor's recognition ability for (bio)chemical sensing. In this review, basic and widely applied device concepts of silicon-based BioFEDs (ion-sensitive field-effect transistor, silicon nanowire transistor, electrolyte-insulator-semiconductor capacitor, light-addressable potentiometric sensor) are presented and recent progress (from 2019 to early 2021) is discussed. One of the main advantages of BioFEDs is the label-free sensing principle enabling to detect a large variety of biomolecules and bioparticles by their intrinsic charge. The review encompasses applications of BioFEDs for the label-free electrical detection of clinically relevant protein biomarkers, deoxyribonucleic acid molecules and viruses, enzyme-substrate reactions as well as recording of the cell acidification rate (as an indicator of cellular metabolism) and the extracellular potential.},
  language  = {en}
}
@article{GamellaZakharchenkoGuzetal.2017,
  author    = {Gamella, Maria and Zakharchenko, Andrey and Guz, Nataliia and Masi, Madeline and Minko, Sergiy and Kolpashchikov, Dmitry M. and Iken, Heiko and Poghossian, Arshak and Sch{\"o}ning, Michael Josef and Katz, Evgeny},
  title     = {DNA computing system activated by electrochemically triggered DNA realease from a polymer-brush-modified electrode array},
  series = {Electroanalysis},
  volume    = {29},
  journal   = {Electroanalysis},
  number    = {2},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1521-4109},
  doi       = {10.1002/elan.201600389},
  pages     = {398 -- 408},
  year      = {2017},
  abstract  = {An array of four independently wired indium tin oxide (ITO) electrodes was used for electrochemically stimulated DNA release and activation of DNA-based Identity, AND and XOR logic gates. Single-stranded DNA molecules were loaded on the mixed poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA)/poly(methacrylic acid) (PMAA) brush covalently attached to the ITO electrodes. The DNA deposition was performed at pH 5.0 when the polymer brush is positively charged due to protonation of tertiary amino groups in PDMAEMA, thus resulting in electrostatic attraction of the negatively charged DNA. By applying electrolysis at -1.0 V(vs. Ag/AgCl reference) electrochemical oxygen reduction resulted in the consumption of hydrogen ions and local pH increase near the electrode surface. The process resulted in recharging the polymer brush to the negative state due to dissociation of carboxylic groups of PMAA, thus repulsing the negatively charged DNA and releasing it from the electrode surface. The DNA release was performed in various combinations from different electrodes in the array assembly. The released DNA operated as input signals for activation of the Boolean logic gates. The developed system represents a step forward in DNA computing, combining for the first time DNA chemical processes with electronic input signals.},
  language  = {en}
}
@article{SousaSiqueiraVerciketal.2017,
  author    = {Sousa, Marcos A. M. and Siqueira, Jose R. Jr. and Vercik, Andres and Sch{\"o}ning, Michael Josef and Oliveira, Osvaldo N. Jr.},
  title     = {Determining the optimized layer-by-layer film architecture with dendrimer/carbon nanotubes for field-effect sensors},
  series = {IEEE Sensors Journal},
  volume    = {17},
  journal   = {IEEE Sensors Journal},
  number    = {6},
  publisher = {IEEE},
  address   = {New York},
  issn      = {1558-1748},
  doi       = {10.1109/JSEN.2017.2653238},
  pages     = {1735 -- 1740},
  year      = {2017},
  abstract  = {The capacitive electrolyte-insulator-semiconductor (EIS) structure is a typical device based on a field-effect sensor platform. With a simple silicon-based structure, EIS have been useful for several sensing applications, especially with incorporation of nanostructured films to modulate the ionic transport and the flat-band potential. In this paper, we report on ion transport and changes in flat-band potential in EIS sensors made with layer-by-layer films containing poly(amidoamine) (PAMAM) dendrimer and single-walled carbon nanotubes (SWNTs) adsorbed on p-Si/SiO 2 /Ta 2 O 5 chips with an Al ohmic contact. The impedance spectra were fitted using an equivalent circuit model, from which we could determine parameters such as the double-layer capacitance. This capacitance decreased with the number of bilayers owing to space charge accumulated at the electrolyte-insulator interface, up to three PAMAM/SWNTs bilayers, after which it stabilized. The charge-transfer resistance was also minimum for three bilayers, thus indicating that this is the ideal architecture for an optimized EIS performance. The understanding of the influence of nanostructures and the fine control of operation parameters pave the way for optimizing the design and performance of new EIS sensors.},
  language  = {en}
}
@article{YoshinobuMiyamotoWerneretal.2017,
  author    = {Yoshinobu, Tatsuo and Miyamoto, Ko-ichiro and Werner, Frederik and Poghossian, Arshak and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {Light-addressable potentiometric sensors for quantitative spatial imaging of chemical species},
  series = {Annual Review of Analytical Chemistry},
  volume    = {10},
  journal   = {Annual Review of Analytical Chemistry},
  publisher = {Annual Reviews},
  address   = {Palo Alto, Calif.},
  issn      = {1936-1327},
  doi       = {10.1146/annurev-anchem-061516-045158},
  pages     = {225 -- 246},
  year      = {2017},
  abstract  = {A light-addressable potentiometric sensor (LAPS) is a semiconductor-based chemical sensor, in which a measurement site on the sensing surface is defined by illumination. This light addressability can be applied to visualize the spatial distribution of pH or the concentration of a specific chemical species, with potential applications in the fields of chemistry, materials science, biology, and medicine. In this review, the features of this chemical imaging sensor technology are compared with those of other technologies. Instrumentation, principles of operation, and various measurement modes of chemical imaging sensor systems are described. The review discusses and summarizes state-of-the-art technologies, especially with regard to the spatial resolution and measurement speed; for example, a high spatial resolution in a submicron range and a readout speed in the range of several tens of thousands of pixels per second have been achieved with the LAPS. The possibility of combining this technology with microfluidic devices and other potential future developments are discussed.},
  language  = {en}
}
@article{BronderPoghossianKeusgenetal.2017,
  author    = {Bronder, Thomas and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Label-free detection of double-stranded DNA molecules with polyelectrolyte-modified capacitive field-effect sensors},
  series = {tm - Technisches Messen},
  volume    = {84},
  journal   = {tm - Technisches Messen},
  number    = {10},
  publisher = {De Gruyter},
  address   = {Oldenbourg},
  doi       = {10.1515/teme-2017-0015},
  pages     = {628 -- 634},
  year      = {2017},
  abstract  = {In this study, polyelectrolyte-modified field-effect-based electrolyte-insulator-semiconductor (EIS) devices have been used for the label-free electrical detection of double-stranded deoxyribonucleic acid (dsDNA)molecules. The sensor-chip functionalization with a positively charged polyelectrolyte layer provides the possibility of direct adsorptive binding of negatively charged target DNA oligonucleotides onto theSiO2-chip surface.EIS sensors can be utilized as a tool to detect surface-charge changes; the electrostatic adsorption of oligonucleotides onto the polyelectrolyte layer leads to a measureable surface-potential change. Signals of 39mV have been recorded after the incubation with the oligonucleotide solution. Besides the electrochemical experiments, the successful adsorption of dsDNA onto the polyelectrolyte layer has been verified via fluorescence microscopy. The presented results demonstrate that the signal recording of EISchips, which are modified with a polyelectrolyte layer, canbe used as a favorable approach for a fast, cheap and simple detection method for dsDNA.},
  language  = {en}
}
@article{ArreolaOberlaenderMaetzkowetal.2017,
  author    = {Arreola, Julio and Oberl{\"a}nder, Jan and M{\"a}tzkow, M. and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Surface functionalization for spore-based biosensors with organosilanes},
  series = {Electrochimica Acta},
  volume    = {241},
  journal   = {Electrochimica Acta},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0013-4686},
  doi       = {10.1016/j.electacta.2017.04.157},
  pages     = {237 -- 243},
  year      = {2017},
  abstract  = {In the present work, surface functionalization of different sensor materials was studied. Organosilanes are well known to serve as coupling agent for biomolecules or cells on inorganic materials. 3-aminopropyltriethoxysilane (APTES) was used to attach microbiological spores time to an interdigitated sensor surface. The functionality and physical properties of APTES were studied on isolated sensor materials, namely silicon dioxide (SiO2) and platinum (Pt) as well as the combined material on sensor level. A predominant immobilization of spores could be demonstrated on SiO2 surfaces. Additionally, the impedance signal of APTES-functionalized biosensor chips has been investigated.},
  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{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}
}
@book{Molinnus2018,
  author    = {Molinnus, Denise},
  title     = {Integration of biomolecular logic principles with electronic transducers on a chip},
  publisher = {Philipps-Universit{\"a}t / Fachbereich Pharmazie},
  address   = {Marburg/Lahn},
  year      = {2018},
  language  = {de}
}
@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}
}
@misc{BergerBiselliDinteretal.2000,
  author    = {Berger, Eric G. and Biselli, Manfred and Dinter, Andr{\´e} and Eisenkr{\"a}tzer, Detlef and Kiesewetter, Andr{\´e} and Zeng, Steffen},
  title     = {Chinese-Hamster-Ovary-Zellen zur Produktion von Proteinen},
  pages     = {1 -- 6},
  year      = {2000},
  language  = {de}
}
@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{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}
}
@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{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{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{FalkenbergRahbaFischeretal.2022,
  author    = {Falkenberg, Fabian and Rahba, Jade and Fischer, David and Bott, Michael and Bongaerts, Johannes and Siegert, Petra},
  title     = {Biochemical characterization of a novel oxidatively stable, halotolerant, and high-alkaline subtilisin from Alkalihalobacillus okhensis Kh10-101T},
  series = {FEBS Open Bio},
  volume    = {12},
  journal   = {FEBS Open Bio},
  number    = {10},
  publisher = {Wiley},
  address   = {Hoboken, NJ},
  issn      = {2211-5463},
  doi       = {10.1002/2211-5463.13457},
  pages     = {1729 -- 1746},
  year      = {2022},
  abstract  = {Halophilic and halotolerant microorganisms represent a promising source of salt-tolerant enzymes suitable for various biotechnological applications where high salt concentrations would otherwise limit enzymatic activity. Considering the current growing enzyme market and the need for more efficient and new biocatalysts, the present study aimed at the characterization of a high-alkaline subtilisin from Alkalihalobacillus okhensis Kh10-101T. The protease gene was cloned and expressed in Bacillus subtilis DB104. The recombinant protease SPAO with 269 amino acids belongs to the subfamily of high-alkaline subtilisins. The biochemical characteristics of purified SPAO were analyzed in comparison with subtilisin Carlsberg, Savinase, and BPN'. SPAO, a monomer with a molecular mass of 27.1 kDa, was active over a wide range of pH 6.0-12.0 and temperature 20-80 °C, optimally at pH 9.0-9.5 and 55 °C. The protease is highly oxidatively stable to hydrogen peroxide and retained 58\% of residual activity when incubated at 10 °C with 5\% (v/v) H2O2 for 1 h while stimulated at 1\% (v/v) H2O2. Furthermore, SPAO was very stable and active at NaCl concentrations up to 5.0 m. This study demonstrates the potential of SPAO for biotechnological applications in the future.},
  language  = {en}
}
@article{MolinnusJanusFangetal.2022,
  author    = {Molinnus, Denise and Janus, Kevin Alexander and Fang, Anyelina C. and Drinic, Aleksander and Achtsnicht, Stefan and K{\"o}pf, Marius and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Thick-film carbon electrode deposited onto a biodegradable fibroin substrate for biosensing applications},
  series = {Physica status solidi (a)},
  volume    = {219},
  journal   = {Physica status solidi (a)},
  number    = {23},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1862-6319},
  doi       = {10.1002/pssa.202200100},
  pages     = {1 -- 9},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}
@article{PourshahidiEngelmannOffenhaeusseretal.2022,
  author    = {Pourshahidi, Ali Mohammad and Engelmann, Ulrich M. and Offenh{\"a}usser, Andreas and Krause, Hans-Joachim},
  title     = {Resolving ambiguities in core size determination of magnetic nanoparticles from magnetic frequency mixing data},
  series = {Journal of Magnetism and Magnetic Materials},
  volume    = {563},
  journal   = {Journal of Magnetism and Magnetic Materials},
  number    = {In progress, Art. No. 169969},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0304-8853},
  doi       = {10.1016/j.jmmm.2022.169969},
  year      = {2022},
  abstract  = {Frequency mixing magnetic detection (FMMD) has been widely utilized as a measurement technique in magnetic immunoassays. It can also be used for the characterization and distinction (also known as "colourization") of different types of magnetic nanoparticles (MNPs) based on their core sizes. In a previous work, it was shown that the large particles contribute most of the FMMD signal. This leads to ambiguities in core size determination from fitting since the contribution of the small-sized particles is almost undetectable among the strong responses from the large ones. In this work, we report on how this ambiguity can be overcome by modelling the signal intensity using the Langevin model in thermodynamic equilibrium including a lognormal core size distribution fL(dc,d0,σ) fitted to experimentally measured FMMD data of immobilized MNPs. For each given median diameter d0, an ambiguous amount of best-fitting pairs of parameters distribution width σ and number of particles Np with R2 > 0.99 are extracted. By determining the samples' total iron mass, mFe, with inductively coupled plasma optical emission spectrometry (ICP-OES), we are then able to identify the one specific best-fitting pair (σ, Np) one uniquely. With this additional externally measured parameter, we resolved the ambiguity in core size distribution and determined the parameters (d0, σ, Np) directly from FMMD measurements, allowing precise MNPs sample characterization.},
  language  = {en}
}
@article{EngelmannPourshahidiShalabyetal.2022,
  author    = {Engelmann, Ulrich M. and Pourshahidi, Mohammad Ali and Shalaby, Ahmed and Krause, Hans-Joachim},
  title     = {Probing particle size dependency of frequency mixing magnetic detection with dynamic relaxation simulation},
  series = {Journal of Magnetism and Magnetic Materials},
  volume    = {563},
  journal   = {Journal of Magnetism and Magnetic Materials},
  number    = {In progress, Art. No. 169965},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0304-8853},
  doi       = {10.1016/j.jmmm.2022.169965},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}
@article{DantismTakenagaWagneretal.2017,
  author    = {Dantism, Shahriar and Takenaga, Shoko and Wagner, Torsten and Wagner, Patrick and Sch{\"o}ning, Michael Josef},
  title     = {Differential imaging of the metabolism of bacteria and eukaryotic cells based on light-addressable potentiometric sensors},
  series = {Electrochimica Acta},
  volume    = {246},
  journal   = {Electrochimica Acta},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0013-4686},
  doi       = {10.1016/j.electacta.2017.05.196},
  pages     = {234 -- 241},
  year      = {2017},
  abstract  = {A light-addressable potentiometric sensor (LAPS) is a field-effect-based potentiometric sensor with an electrolyte/insulator/semiconductor (EIS) structure, which is able to monitor analyte concentrations of (bio-)chemical species in aqueous solutions in a spatially resolved way. Therefore, it is also an appropriate tool to record 2D-chemical images of concentration variations on the sensor surface. In the present work, two differential, LAPS-based measurement principles are introduced to determine the metabolic activity of Escherichia coli (E. coli) K12 and Chinese hamster ovary (CHO) cells as test microorganisms. Hereby, we focus on i) the determination of the extracellular acidification rate (ΔpH/min) after adding glucose solutions to the cell suspensions; and ii) recording the amplitude increase of the photocurrent (Iph) related to the produced acids from E. coli K12 bacteria and CHO cells on the sensor surface by 2D-chemical imaging. For this purpose, 3D-printed multi-chamber structures were developed and mounted on the planar sensor-chip surface to define four independent compartments, enabling differential measurements with varying cell concentrations. The differential concept allows eliminating unwanted drift effects and, with the four-chamber structures, measurements on the different cell concentrations were performed simultaneously, thus reducing also the overall measuring time.},
  language  = {en}
}
@article{JildehKirchnerOberlaenderetal.2017,
  author    = {Jildeh, Zaid B. and Kirchner, Patrick and Oberl{\"a}nder, Jan and Kremers, Alexander and Wagner, Torsten and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef},
  title     = {FEM-based modeling of a calorimetric gas sensor for hydrogen peroxide monitoring},
  series = {physica status solidi a : applications and materials sciences},
  journal   = {physica status solidi a : applications and materials sciences},
  number    = {Early View},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1862-6319},
  doi       = {10.1002/pssa.201600912},
  year      = {2017},
  abstract  = {A physically coupled finite element method (FEM) model is developed to study the response behavior of a calorimetric gas sensor. The modeled sensor serves as a monitoring device of the concentration of gaseous hydrogen peroxide (H2 O2) in a high temperature mixture stream in aseptic sterilization processes. The principle of operation of a calorimetric H2 O2 sensor is analyzed and the results of the numerical model have been validated by using previously published sensor experiments. The deviation in the results between the FEM model and experimental data are presented and discussed.},
  language  = {en}
}
@article{MolinnusPoghossianKeusgenetal.2017,
  author    = {Molinnus, Denise and Poghossian, Arshak and Keusgen, Michael and Katz, Evgeny and Sch{\"o}ning, Michael Josef},
  title     = {Coupling of Biomolecular Logic Gates with Electronic Transducers: From Single Enzyme Logic Gates to Sense/Act/Treat Chips},
  series = {Electroanalysis},
  volume    = {29},
  journal   = {Electroanalysis},
  number    = {8},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1521-4109},
  doi       = {10.1002/elan.201700208},
  pages     = {1840 -- 1849},
  year      = {2017},
  abstract  = {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.},
  language  = {en}
}
@article{ArreolaKeusgenSchoening2017,
  author    = {Arreola, Julio and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Effect of O2 plasma on properties of electrolyte-insulator-semiconductor structures},
  series = {physica status solidi a : applications and materials sciences},
  volume    = {214},
  journal   = {physica status solidi a : applications and materials sciences},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1862-6319},
  doi       = {10.1002/pssa.201700025},
  pages     = {Artikel 1700025},
  year      = {2017},
  abstract  = {Prior to immobilization of biomolecules or cells onto biosensor surfaces, the surface must be physically or chemically activated for further functionalization. Organosilanes are a versatile option as they facilitate the immobilization through their terminal groups and also display self-assembly. Incorporating hydroxyl groups is one of the important methods for primary immobilization. This can be done, for example, with oxygen plasma treatment. However, this treatment can affect the performance of the biosensors and this effect is not quite well understood for surface functionalization. In this work, the effect of O2 plasma treatment on EIS sensors was investigated by means of electrochemical characterizations: capacitance-voltage (C-V) and constant capacitance (ConCap) measurements. After O2 plasma treatment, the potential of the EIS sensor dramatically shifts to a more negative value. This was successfully reset by using an annealing process.},
  language  = {en}
}
@article{MiyamotoHayashiSakamotoetal.2017,
  author    = {Miyamoto, Ko-ichiro and Hayashi, Kosuke and Sakamoto, Azuma and Werner, Frederik and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {A high-Q resonance-mode measurement of EIS capacitive sensor by elimination of series resistance},
  series = {Sensor and Actuators B: Chemical},
  volume    = {248},
  journal   = {Sensor and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2017.03.002},
  pages     = {1006 -- 1010},
  year      = {2017},
  abstract  = {An EIS capacitive sensor is a semiconductor-based potentiometric sensor, which is sensitive to the ion concentration or pH value of the solution in contact with the sensing surface. To detect a small change in the ion concentration or pH, a small capacitance change must be detected. Recently, a resonance-mode measurement was proposed, in which an inductor was connected to the EIS capacitive sensor and the resonant frequency was correlated with the pH value. In this study, the Q factor of the resonant circuit was enhanced by canceling the internal resistance of the reference electrode and the internal resistance of the inductor coil with the help of a bypass capacitor and a negative impedance converter, respectively. 1\% variation of the signal in the developed system corresponded to a pH change of 3.93 mpH, which was about 1/12 of the conventional method, suggesting a better performance in detection of a small pH change.},
  language  = {en}
}
@article{WernerMiyamotoWagneretal.2017,
  author    = {Werner, Frederik and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Lateral resolution enhancement of pulse-driven light-addressable potentiometric sensor},
  series = {Sensor and Actuators B: Chemical},
  volume    = {248},
  journal   = {Sensor and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2017.02.057},
  pages     = {961 -- 965},
  year      = {2017},
  abstract  = {To study chemical and biological processes, spatially resolved determination of the concentrations of one or more analyte species is of distinct interest. With a light-addressable potentiometric sensor (LAPS), chemical images can be created, which visualize the concentration distribution above the sensor plate. One important challenge is to achieve a good lateral resolution in order to detect events that take place in a small and limited region. LAPS utilizes a focused light spot to address the measurement region. By moving this light spot along the semiconductor sensor plate, the concentration distribution can be observed. In this study, we show that utilizing a pulse as light excitation instead of a traditionally used continuously modulated light excitation, the lateral resolution can be improved by a factor of 6 or more.},
  language  = {en}
}
@article{SchollMoraisGabrieletal.2017,
  author    = {Scholl, Fabio and Morais, Paulo and Gabriel, Rayla and Sch{\"o}ning, Michael Josef and Siqueira, Jose Roberto, Jr. and Caseli, Luciano},
  title     = {Carbon nanotubes arranged as smart interfaces in lipid Langmuir-Blodgett films enhancing the enzymatic properties of penicillinase for biosensing applications},
  series = {Applied Materials \& Interfaces},
  volume    = {9},
  journal   = {Applied Materials \& Interfaces},
  number    = {36},
  publisher = {ACS},
  address   = {Washington},
  issn      = {1944-8252},
  doi       = {10.1021/acsami.7b08095},
  pages     = {31054 -- 31066},
  year      = {2017},
  abstract  = {In this paper, carbon nanotubes (CNTs) were incorporated in penicillinase-phospholipid Langmuir and Langmuir-Blodgett (LB) films to enhance the enzyme catalytic properties. Adsorption of the penicillinase and CNTs at dimyristoylphosphatidic acid (DMPA) monolayers at the air-water interface was investigated by surface pressure-area isotherms, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to solid supports through the LB technique, forming mixed DMPA-CNTs-PEN films, which were investigated by quartz crystal microbalance, vibrational spectroscopy, and atomic force microscopy. Enzyme activity was studied with UV-vis spectroscopy and the feasibility of the supramolecular device nanostructured as ultrathin films were essayed in a capacitive electrolyte-insulator-semiconductor (EIS) sensor device. The presence of CNTs in the enzyme-lipid LB film not only tuned the catalytic activity of penicillinase but also helped conserve its enzyme activity after weeks, showing increased values of activity. Viability as penicillin sensor was demonstrated with capacitance/voltage and constant capacitance measurements, exhibiting regular and distinctive output signals over all concentrations used in this work. These results may be related not only to the nanostructured system provided by the film, but also to the synergism between the compounds on the active layer, leading to a surface morphology that allowed a fast analyte diffusion because of an adequate molecular accommodation, which also preserved the penicillinase activity. This work therefore demonstrates the feasibility of employing LB films composed of lipids, CNTs, and enzymes as EIS devices for biosensing applications.},
  language  = {en}
}
@inproceedings{JablonskiKochBronderetal.2017,
  author    = {Jablonski, Melanie and Koch, Claudia and Bronder, Thomas and Poghossian, Arshak and Wege, Christina and Sch{\"o}ning, Michael Josef},
  title     = {Field-Effect Biosensors Modified with Tobacco Mosaic Virus Nanotubes as Enzyme Nanocarrier},
  series = {MDPI Proceeding},
  volume    = {1},
  booktitle = {MDPI Proceeding},
  number    = {4},
  doi       = {10.3390/proceedings1040505},
  pages     = {4},
  year      = {2017},
  language  = {en}
}
@inproceedings{OberlaenderArreolaHansenetal.2017,
  author    = {Oberl{\"a}nder, Jan and Arreola, Julio and Hansen, Christina and Greeff, Anton and Mayer, Marlena and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Impedimetric Biosensor to Enable Fast Evaluation of Gaseous Sterilization Processes},
  series = {MDPI Proceedings},
  volume    = {1},
  booktitle = {MDPI Proceedings},
  number    = {4},
  doi       = {10.3390/proceedings1040435},
  pages     = {4 Seiten},
  year      = {2017},
  language  = {en}
}
@inproceedings{MolinnusHardtKaeveretal.2017,
  author    = {Molinnus, Denise and Hardt, Gabriel and K{\"a}ver, Larissa and Willenberg, Holger S. and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Detection of Adrenaline Based on Bioelectrocatalytical System to Support Tumor Diagnostic Technology},
  series = {MDPI Proceedings},
  booktitle = {MDPI Proceedings},
  doi       = {10.3390/proceedings1040506},
  pages     = {4 Seiten},
  year      = {2017},
  language  = {en}
}
@article{MuschallikMolinnusBongaertsetal.2017,
  author    = {Muschallik, Lukas and Molinnus, Denise and Bongaerts, Johannes and Pohl, Martina and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Siegert, Petra and Selmer, Thorsten},
  title     = {(R,R)-Butane-2,3-diol Dehydrogenase from Bacillus clausii DSM 8716T: Cloning and Expression of the bdhA-Gene, and Initial Characterization of Enzyme},
  series = {Journal of Biotechnology},
  volume    = {258},
  journal   = {Journal of Biotechnology},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0168-1656},
  doi       = {10.1016/j.jbiotec.2017.07.020},
  pages     = {41 -- 50},
  year      = {2017},
  abstract  = {The gene encoding a putative (R,R)-butane-2,3-diol dehydrogenase (bdhA) from Bacillus clausii DSM 8716T was isolated, sequenced and expressed in Escherichia coli. The amino acid sequence of the encoded protein is only distantly related to previously studied enzymes (identity 33-43\%) and exhibited some uncharted peculiarities. An N-terminally StrepII-tagged enzyme variant was purified and initially characterized. The isolated enzyme catalyzed the (R)-specific oxidation of (R,R)- and meso-butane-2,3-diol to (R)- and (S)-acetoin with specific activities of 12 U/mg and 23 U/mg, respectively. Likewise, racemic acetoin was reduced with a specific activity of up to 115 U/mg yielding a mixture of (R,R)- and meso-butane-2,3-diol, while the enzyme reduced butane-2,3-dione (Vmax 74 U/mg) solely to (R,R)-butane-2,3-diol via (R)-acetoin. For these reactions only activity with the co-substrates NADH/NAD+ was observed. The enzyme accepted a selection of vicinal diketones, α-hydroxy ketones and vicinal diols as alternative substrates. Although the physiological function of the enzyme in B. clausii remains elusive, the data presented herein clearly demonstrates that the encoded enzyme is a genuine (R,R)-butane-2,3-diol dehydrogenase with potential for applications in biocatalysis and sensor development.},
  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{MoraisGomesSilvaetal.2017,
  author    = {Morais, Paulo V. and Gomes, Vanderley F., Jr. and Silva, Anielle C. A. and Dantas, Noelio O. and Sch{\"o}ning, Michael Josef and Siqueira, Jos{\´e} R., Jr.},
  title     = {Nanofilm of ZnO nanocrystals/carbon nanotubes as biocompatible layer for enzymatic biosensors in capacitive field-effect devices},
  series = {Journal of Materials Science},
  volume    = {52},
  journal   = {Journal of Materials Science},
  number    = {20},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1573-4803},
  doi       = {10.1007/s10853-017-1369-y},
  pages     = {12314 -- 12325},
  year      = {2017},
  abstract  = {The incorporation of nanomaterials that are biocompatible with different types of biological compounds has allowed the development of a new generation of biosensors applied especially in the biomedical field. In particular, the integration of film-based nanomaterials employed in field-effect devices can be interesting to develop biosensors with enhanced properties. In this paper, we studied the fabrication of sensitive nanofilms combining ZnO nanocrystals and carbon nanotubes (CNTs), prepared by means of the layer-by-layer (LbL) technique, in a capacitive electrolyte-insulator-semiconductor (EIS) structure for detecting glucose and urea. The ZnO nanocrystals were incorporated in a polymeric matrix of poly(allylamine) hydrochloride (PAH), and arranged with multi-walled CNTs in a LbL PAH-ZnO/CNTs film architecture onto EIS chips. The electrochemical characterizations were performed by capacitance-voltage and constant capacitance measurements, while the morphology of the films was characterized by atomic force microscopy. The enzymes glucose oxidase and urease were immobilized on film's surface for detection of glucose and urea, respectively. In order to obtain glucose and urea biosensors with optimized amount of sensitive films, we investigated the ideal number of bilayers for each detection system. The glucose biosensor showed better sensitivity and output signal for an LbL PAH-ZnO/CNTs nanofilm with 10 bilayers. On the other hand, the urea biosensor presented enhanced properties even for the first bilayer, exhibiting high sensitivity and output signal. The presence of the LbL PAH-ZnO/CNTs films led to biosensors with better sensitivity and enhanced response signal, demonstrating that the adequate use of nanostructured films is feasible for proof-of-concept biosensors with improved properties that may be employed for biomedical applications.},
  language  = {en}
}
@article{HonarvarfardGamellaPoghossianetal.2017,
  author    = {Honarvarfard, Elham and Gamella, Maria and Poghossian, Arshak and Sch{\"o}ning, Michael Josef and Katz, Evgeny},
  title     = {An enzyme-based reversible Controlled NOT (CNOT) logic gate operating on a semiconductor transducer},
  series = {Applied Materials Today},
  volume    = {9},
  journal   = {Applied Materials Today},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {2352-9407},
  doi       = {10.1016/j.apmt.2017.08.003},
  pages     = {266 -- 270},
  year      = {2017},
  abstract  = {An enzyme-based biocatalytic system mimicking operation of a logically reversible Controlled NOT (CNOT) gate has been interfaced with semiconductor electronic transducers. Electrolyte-insulator-semiconductor (EIS) structures have been used to transduce chemical changes produced by the enzyme system to an electronically readable capacitive output signal using field-effect features of the EIS device. Two enzymes, urease and esterase, were immobilized on the insulating interface of EIS structure producing local pH changes performing XOR logic operation controlled by various combinations of the input signals represented by urea and ethyl butyrate. Another EIS transducer was functionalized with esterase only, thus performing Identity (ID) logic operation for the ethyl butyrate input. Both semiconductor devices assembled in parallel operated as a logically reversible CNOT gate. The present system, despite its simplicity, demonstrated for the first time logically reversible function of the enzyme system transduced electronically with the semiconductor devices. The biomolecular realization of a CNOT gate interfaced with semiconductors is promising for integration into complex biomolecular networks and future biosensor/biomedical applications.},
  language  = {en}
}
@article{RoehlenPilasSchoeningetal.2017,
  author    = {R{\"o}hlen, Desiree and Pilas, Johanna and Sch{\"o}ning, Michael Josef and Selmer, Thorsten},
  title     = {Development of an amperometric biosensor platform for the combined determination of l-Malic, Fumaric, and l-Aspartic acid},
  series = {Applied Biochemistry and Biotechnology},
  volume    = {183},
  journal   = {Applied Biochemistry and Biotechnology},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1559-0291},
  doi       = {10.1007/s12010-017-2578-1},
  pages     = {566 -- 581},
  year      = {2017},
  abstract  = {Three amperometric biosensors have been developed for the detection of L-malic acid, fumaric acid, and L -aspartic acid, all based on the combination of a malate-specific dehydrogenase (MDH, EC 1.1.1.37) and diaphorase (DIA, EC 1.8.1.4). The stepwise expansion of the malate platform with the enzymes fumarate hydratase (FH, EC 4.2.1.2) and aspartate ammonia-lyase (ASPA, EC 4.3.1.1) resulted in multi-enzyme reaction cascades and, thus, augmentation of the substrate spectrum of the sensors. Electrochemical measurements were carried out in presence of the cofactor β-nicotinamide adenine dinucleotide (NAD+) and the redox mediator hexacyanoferrate (III) (HCFIII). The amperometric detection is mediated by oxidation of hexacyanoferrate (II) (HCFII) at an applied potential of + 0.3 V vs. Ag/AgCl. For each biosensor, optimum working conditions were defined by adjustment of cofactor concentrations, buffer pH, and immobilization procedure. Under these improved conditions, amperometric responses were linear up to 3.0 mM for L-malate and fumarate, respectively, with a corresponding sensitivity of 0.7 μA mM-1 (L-malate biosensor) and 0.4 μA mM-1 (fumarate biosensor). The L-aspartate detection system displayed a linear range of 1.0-10.0 mM with a sensitivity of 0.09 μA mM-1. The sensor characteristics suggest that the developed platform provides a promising method for the detection and differentiation of the three substrates.},
  language  = {en}
}
@article{PilasYaziciSelmeretal.2017,
  author    = {Pilas, Johanna and Yazici, Yasemen and Selmer, Thorsten and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Optimization of an amperometric biosensor array for simultaneous measurement of ethanol, formate, d- and l-lactate},
  series = {Electrochimica Acta},
  volume    = {251},
  journal   = {Electrochimica Acta},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0013-4686},
  doi       = {10.1016/j.electacta.2017.07.119},
  pages     = {256 -- 262},
  year      = {2017},
  abstract  = {The immobilization of NAD+-dependent dehydrogenases, in combination with a diaphorase, enables the facile development of multiparametric sensing devices. In this work, an amperometric biosensor array for simultaneous determination of ethanol, formate, d- and l-lactate is presented. Enzyme immobilization on platinum thin-film electrodes was realized by chemical cross-linking with glutaraldehyde. The optimization of the sensor performance was investigated with regard to enzyme loading, glutaraldehyde concentration, pH, cofactor concentration and temperature. Under optimal working conditions (potassium phosphate buffer with pH 7.5, 2.5 mmol L-1 NAD+, 2.0 mmol L-1 ferricyanide, 25 °C and 0.4\% glutaraldehyde) the linear working range and sensitivity of the four sensor elements was improved. Simultaneous and cross-talk free measurements of four different metabolic parameters were performed successfully. The reliable analytical performance of the biosensor array was demonstrated by application in a clarified sample of inoculum sludge. Thereby, a promising approach for on-site monitoring of fermentation processes is provided.},
  language  = {en}
}
@article{BreuerMangSchoeningetal.2017,
  author    = {Breuer, Lars and Mang, Thomas and Sch{\"o}ning, Michael Josef and Thoelen, Ronald and Wagner, Torsten},
  title     = {Investigation of the spatial resolution of a laser-based stimulation process for light-addressable hydrogels with incorporated graphene oxide by means of IR thermography},
  series = {Sensors and Actuators A: Physical},
  volume    = {268},
  journal   = {Sensors and Actuators A: Physical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0924-4247},
  doi       = {10.1016/j.sna.2017.11.031},
  pages     = {126 -- 132},
  year      = {2017},
  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}
}
@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}
}