@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} } @inproceedings{BreuerGuthmannSchoeningetal.2017, author = {Breuer, Lars and Guthmann, Eric and Sch{\"o}ning, Michael Josef and Thoelen, Ronald and Wagner, Torsten}, title = {Light-Stimulated Hydrogels with Incorporated Graphene Oxide as Actuator Material for Flow Control in Microfluidic Applications}, series = {Proceedings Eurosensors 2017 Conference, Paris, France, 3-6 September 2017}, booktitle = {Proceedings Eurosensors 2017 Conference, Paris, France, 3-6 September 2017}, doi = {10.3390/proceedings1040524}, pages = {1 -- 4}, year = {2017}, 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{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} } @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} } @incollection{SchoeningWagnerPoghossianetal.2018, author = {Sch{\"o}ning, Michael Josef and Wagner, Torsten and Poghossian, Arshak and Miyamoto, K.I. and Werner, C.F. and Krause, S. and Yoshinobu, T.}, title = {Light-addressable potentiometric sensors for (bio-)chemical sensing and imaging}, series = {Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry. Vol. 7}, booktitle = {Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry. Vol. 7}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {9780128097397}, pages = {295 -- 308}, year = {2018}, 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{OezsoyluKizildagSchoeningetal.2020, author = {{\"O}zsoylu, Dua and Kizildag, Sefa and Sch{\"o}ning, Michael Josef and Wagner, Torsten}, title = {Differential chemical imaging of extracellular acidification within microfluidic channels using a plasma-functionalized light-addressable potentiometric sensor (LAPS)}, series = {Physics in Medicine}, volume = {10}, journal = {Physics in Medicine}, number = {100030}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2352-4510}, doi = {10.1016/j.phmed.2020.100030}, pages = {8}, year = {2020}, abstract = {Extracellular acidification is a basic indicator for alterations in two vital metabolic pathways: glycolysis and cellular respiration. Measuring these alterations by monitoring extracellular acidification using cell-based biosensors such as LAPS plays an important role in studying these pathways whose disorders are associated with numerous diseases including cancer. However, the surface of the biosensors must be specially tailored to ensure high cell compatibility so that cells can represent more in vivo-like behavior, which is critical to gain more realistic in vitro results from the analyses, e.g., drug discovery experiments. In this work, O2 plasma patterning on the LAPS surface is studied to enhance surface features of the sensor chip, e.g., wettability and biofunctionality. The surface treated with O2 plasma for 30 s exhibits enhanced cytocompatibility for adherent CHO-K1 cells, which promotes cell spreading and proliferation. The plasma-modified LAPS chip is then integrated into a microfluidic system, which provides two identical channels to facilitate differential measurements of the extracellular acidification of CHO-K1 cells. To the best of our knowledge, it is the first time that extracellular acidification within microfluidic channels is quantitatively visualized as differential (bio-)chemical images.}, language = {en} } @article{MuschallikKippReckeretal.2020, author = {Muschallik, Lukas and Kipp, Carina Ronja and Recker, Inga and Bongaerts, Johannes and Pohl, Martina and Gelissen, Melanie and Sch{\"o}ning, Michael Josef and Selmer, Thorsten and Siegert, Petra}, title = {Synthesis of α-hydroxy ketones and vicinal diols with the Bacillus licheniformis DSM 13T butane-2, 3-diol dehydrogenase}, series = {Journal of Biotechnology}, volume = {202}, journal = {Journal of Biotechnology}, number = {Vol. 324}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {2590-1559}, doi = {10.1016/j.jbiotec.2020.09.016}, pages = {61 -- 70}, year = {2020}, abstract = {The enantioselective synthesis of α-hydroxy ketones and vicinal diols is an intriguing field because of the broad applicability of these molecules. Although, butandiol dehydrogenases are known to play a key role in the production of 2,3-butandiol, their potential as biocatalysts is still not well studied. Here, we investigate the biocatalytic properties of the meso-butanediol dehydrogenase from Bacillus licheniformis DSM 13T (BlBDH). The encoding gene was cloned with an N-terminal StrepII-tag and recombinantly overexpressed in E. coli. BlBDH is highly active towards several non-physiological diketones and α-hydroxyketones with varying aliphatic chain lengths or even containing phenyl moieties. By adjusting the reaction parameters in biotransformations the formation of either the α-hydroxyketone intermediate or the diol can be controlled.}, language = {en} } @article{MolinnusIkenJohnenetal.2022, author = {Molinnus, Denise and Iken, Heiko and Johnen, Anna Lynn and Richstein, Benjamin and Hellmich, Lena and Poghossian, Arshak and Knoch, Joachim and Sch{\"o}ning, Michael Josef}, title = {Miniaturized pH-Sensitive Field-Effect Capacitors with Ultrathin Ta₂O₅ Films Prepared by Atomic Layer Deposition}, series = {physica status solidi (a) applications and materials science}, volume = {219}, journal = {physica status solidi (a) applications and materials science}, number = {8}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6319}, doi = {10.1002/pssa.202100660}, pages = {7 Seiten}, year = {2022}, abstract = {Miniaturized electrolyte-insulator-semiconductor capacitors (EISCAPs) with ultrathin gate insulators have been studied in terms of their pH-sensitive sensor characteristics: three different EISCAP systems consisting of Al-p-Si-Ta2O5(5 nm), Al-p-Si-Si3N4(1 or 2 nm)-Ta2O5 (5 nm), and Al-p-Si-SiO2(3.6 nm)-Ta2O5(5 nm) layer structures are characterized in buffer solution with different pH values by means of capacitance-voltage and constant capacitance method. The SiO2 and Si3N4 gate insulators are deposited by rapid thermal oxidation and rapid thermal nitridation, respectively, whereas the Ta2O5 film is prepared by atomic layer deposition. All EISCAP systems have a clear pH response, favoring the stacked gate insulators SiO2-Ta2O5 when considering the overall sensor characteristics, while the Si3N4(1 nm)-Ta2O5 stack delivers the largest accumulation capacitance (due to the lower equivalent oxide thickness) and a higher steepness in the slope of the capacitance-voltage curve among the studied stacked gate insulator systems.}, language = {en} } @article{OliveiraMolinnusBegingetal.2021, author = {Oliveira, Danilo A. and Molinnus, Denise and Beging, Stefan and Siqueira Jr, Jos{\´e} R. and Sch{\"o}ning, Michael Josef}, title = {Biosensor Based on Self-Assembled Films of Graphene Oxide and Polyaniline Using a Field-Effect Device Platform}, series = {physica status solidi (a) applications and materials science}, volume = {218}, journal = {physica status solidi (a) applications and materials science}, number = {13}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6319}, doi = {10.1002/pssa.202000747}, pages = {1 -- 9}, year = {2021}, abstract = {A new functionalization method to modify capacitive electrolyte-insulator-semiconductor (EIS) structures with nanofilms is presented. Layers of polyallylamine hydrochloride (PAH) and graphene oxide (GO) with the compound polyaniline:poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PANI:PAAMPSA) are deposited onto a p-Si/SiO2 chip using the layer-by-layer technique (LbL). Two different enzymes (urease and penicillinase) are separately immobilized on top of a five-bilayer stack of the PAH:GO/PANI:PAAMPSA-modified EIS chip, forming a biosensor for detection of urea and penicillin, respectively. Electrochemical characterization is performed by constant capacitance (ConCap) measurements, and the film morphology is characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). An increase in the average sensitivity of the modified biosensors (EIS-nanofilm-enzyme) of around 15\% is found in relation to sensors, only carrying the enzyme but without the nanofilm (EIS-enzyme). In this sense, the nanofilm acts as a stable bioreceptor onto the EIS chip improving the output signal in terms of sensitivity and stability.}, language = {en} } @article{WeldenNagamineKomesuWagneretal.2021, author = {Welden, Rene and Nagamine Komesu, Cindy A. and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef and Wagner, Torsten}, title = {Photoelectrochemical enzymatic penicillin biosensor: A proof-of-concept experiment}, series = {Electrochemical Science Advances}, volume = {2}, journal = {Electrochemical Science Advances}, number = {4}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2698-5977}, doi = {10.1002/elsa.202100131}, pages = {1 -- 5}, year = {2021}, abstract = {Photoelectrochemical (PEC) biosensors are a rather novel type of biosensors thatutilizelighttoprovideinformationaboutthecompositionofananalyte,enablinglight-controlled multi-analyte measurements. For enzymatic PEC biosensors,amperometric detection principles are already known in the literature. In con-trast, there is only a little information on H+-ion sensitive PEC biosensors. Inthis work, we demonstrate the detection of H+ions emerged by H+-generatingenzymes, exemplarily demonstrated with penicillinase as a model enzyme on atitanium dioxide photoanode. First, we describe the pH sensitivity of the sensorand study possible photoelectrocatalytic reactions with penicillin. Second, weshow the enzymatic PEC detection of penicillin.}, language = {en} } @article{PoghossianWernerBuniatyanetal.2017, author = {Poghossian, Arshak and Werner, Frederik and Buniatyan, V. V. and Wagner, Torsten and Miamoto, K. and Yoshinobu, T. and Sch{\"o}ning, Michael Josef}, title = {Towards addressability of light-addressable potentiometric sensors: Shunting effect of non-illuminated region and cross-talk}, series = {Sensor and Actuators B: Chemical}, journal = {Sensor and Actuators B: Chemical}, number = {244}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2017.01.047}, pages = {1071 -- 1079}, year = {2017}, abstract = {The LAPS (light-addressable potentiometric sensor) platform is one of the most attractive approaches for chemical and biological sensing with many applications ranging from pH and ion/analyte concentration measurements up to cell metabolism detection and chemical imaging. However, although it is generally accepted that LAPS measurements are spatially resolved, the light-addressability feature of LAPS devices has not been discussed in detail so far. In this work, an extended electrical equivalent-circuit model of the LAPS has been presented, which takes into account possible cross-talk effects due to the capacitive coupling of the non-illuminated region. A shunting effect of the non-illuminated area on the measured photocurrent and addressability of LAPS devices has been studied. It has been shown, that the measured photocurrent will be determined not only by the local interfacial potential in the illuminated region but also by possible interfacial potential changes in the non-illuminated region, yielding cross-talk effects. These findings were supported by the experimental investigations of a penicillin-sensitive multi-spot LAPS and a metal-insulator-semiconductor LAPS as model systems.}, language = {en} } @inproceedings{BaeckerKochGeigeretal.2016, author = {B{\"a}cker, Matthias and Koch, C. and Geiger, F. and Eber, F. and Gliemann, H. and Poghossian, Arshak and Sch{\"o}ning, Michael Josef}, title = {A New Class of Biosensors Based on Tobacco Mosaic Virus and Coat Proteins as Enzyme Nanocarrier}, series = {Procedia Engineering}, volume = {Vol. 168}, booktitle = {Procedia Engineering}, issn = {1877-7058}, doi = {10.1016/j.proeng.2016.11.228}, pages = {618 -- 621}, year = {2016}, language = {en} } @article{KatzPoghossianSchoening2017, author = {Katz, Evgeny and Poghossian, Arshak and Sch{\"o}ning, Michael Josef}, title = {Enzyme-based logic gates and circuits - analytical applications and interfacing with electronics}, series = {Analytical and Bioanalytical Chemistry}, volume = {409}, journal = {Analytical and Bioanalytical Chemistry}, publisher = {Springer}, address = {Berlin}, issn = {1618-2650}, doi = {10.1007/s00216-016-0079-7}, pages = {81 -- 94}, year = {2017}, abstract = {The paper is an overview of enzyme-based logic gates and their short circuits, with specific examples of Boolean AND and OR gates, and concatenated logic gates composed of multi-step enzyme-biocatalyzed reactions. Noise formation in the biocatalytic reactions and its decrease by adding a "filter" system, converting convex to sigmoid response function, are discussed. Despite the fact that the enzyme-based logic gates are primarily considered as components of future biomolecular computing systems, their biosensing applications are promising for immediate practical use. Analytical use of the enzyme logic systems in biomedical and forensic applications is discussed and exemplified with the logic analysis of biomarkers of various injuries, e.g., liver injury, and with analysis of biomarkers characteristic of different ethnicity found in blood samples on a crime scene. Interfacing of enzyme logic systems with modified electrodes and semiconductor devices is discussed, giving particular attention to the interfaces functionalized with signal-responsive materials. Future perspectives in the design of the biomolecular logic systems and their applications are discussed in the conclusion.}, language = {en} } @inproceedings{PoghossianBronderSchejaetal.2016, author = {Poghossian, Arshak and Bronder, Thomas and Scheja, S. and Wu, Chunsheng and Metzger-Boddien, C. and Keusgen, M. and Sch{\"o}ning, Michael Josef}, title = {Label-free Electrostatic Detection of DNA Amplification by PCR Using Capacitive Field-effect Devices}, series = {Procedia Engineering}, volume = {Vol. 168}, booktitle = {Procedia Engineering}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1877-7058}, doi = {10.1016/j.proeng.2016.11.512}, pages = {514 -- 517}, year = {2016}, abstract = {A capacitive field-effect EIS (electrolyte-insulator-semiconductor) sensor modified with a positively charged weak polyelectrolyte of poly(allylamine hydrochloride) (PAH)/single-stranded probe DNA (ssDNA) bilayer has been used for a label-free electrostatic detection of pathogen-specific DNA amplification via polymerase chain reaction (PCR). The sensor is able to distinguish between positive and negative PCR solutions, to detect the existence of target DNA amplicons in PCR samples and thus, can be used as tool for a quick verification of DNA amplification and the successful PCR process.}, language = {en} } @article{HonarvarfardGamellaChannaveerappaetal.2017, author = {Honarvarfard, Elham and Gamella, Maria and Channaveerappa, Devika and Darie, Costel C. and Poghossian, Arshak and Sch{\"o}ning, Michael Josef and Katz, Evgeny}, title = {Electrochemically Stimulated Insulin Release from a Modified Graphene-functionalized Carbon Fiber Electrode}, series = {Electroanalysis}, volume = {29}, journal = {Electroanalysis}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-4109}, doi = {10.1002/elan.201700095}, pages = {1543 -- 1553}, year = {2017}, abstract = {A graphene-functionalized carbon fiber electrode was modified with adsorbed polyethylenimine to introduce amino functionalities and then with trigonelline and 4-carboxyphenylboronic acid covalently bound to the amino groups. The trigonelline species containing quarterized pyridine groups produced positive charge on the electrode surface regardless of the pH value, while the phenylboronic acid species were neutral below pH 8 and negatively charged above pH 9 (note that their pKa=8.4). The total charge on the monolayer-modified electrode was positive at the neutral pH and negative at pH > 9. Note that 4-carboxyphenylboronic acid was attached to the electrode surface in molar excess to trigonelline, thus allowing the negative charge to dominate on the electrode surface at basic pH. Negatively charged fluorescent dye-labeled insulin (insulin-FITC) was loaded on the modified electrode surface at pH 7.0 due to its electrostatic attraction to the positively charged interface. The local pH in close vicinity to the electrode surface was increased to ca. 9-10 due to consumption of H+ ions upon electrochemical reduction of oxygen proceeding at the potential of -1.0 V (vs. Ag/AgCl) applied on the modified electrode. The process resulted in recharging of the electrode surface to the negative value due to the formation of the negative charge on the phenylboronic acid groups, thus resulting in the electrostatic repulsion of insulin-FITC and stimulating its release from the electrode surface. The insulin release was characterized by fluorescence spectroscopy (using the FITC-labeled insulin), by electrochemical measurements on an iridium oxide, IrOx, electrode and by mass spectrometry. The graphene-functionalized carbon fiber electrode demonstrated significant advantages in the signal-stimulated insulin release comparing with the carbon fiber electrode without the graphene species.}, language = {en} } @article{JildehWagnerSchoening2021, author = {Jildeh, Zaid B. and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef}, title = {Sterilization of Objects, Products, and Packaging Surfaces and Their Characterization in Different Fields of Industry: The Status in 2020}, series = {physica status solidi (a) applications and materials science}, volume = {218}, journal = {physica status solidi (a) applications and materials science}, number = {13}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6319}, doi = {10.1002/pssa.202000732}, pages = {27 Seiten}, year = {2021}, abstract = {The treatment method to deactivate viable microorganisms from objects or products is termed sterilization. There are multiple forms of sterilization, each intended to be applied for a specific target, which depends on—but not limited to—the thermal, physical, and chemical stability of that target. Herein, an overview on the currently used sterilization processes in the global market is provided. Different sterilization techniques are grouped under a category that describes the method of treatment: radiation (gamma, electron beam, X-ray, and ultraviolet), thermal (dry and moist heat), and chemical (ethylene oxide, ozone, chlorine dioxide, and hydrogen peroxide). For each sterilization process, the typical process parameters as defined by regulations and the mode of antimicrobial activity are summarized. Finally, the recommended microorganisms that are used as biological indicators to validate sterilization processes in accordance with the rules that are established by various regulatory agencies are summarized.}, language = {en} } @article{MolinnusDrinicIkenetal.2021, author = {Molinnus, Denise and Drinic, Aleksander and Iken, Heiko and Kr{\"o}ger, Nadja and Zinser, Max and Smeets, Ralf and K{\"o}pf, Marius and Kopp, Alexander and Sch{\"o}ning, Michael Josef}, title = {Towards a flexible electrochemical biosensor fabricated from biocompatible Bombyx mori silk}, series = {Biosensors and Bioelectronics}, volume = {183}, journal = {Biosensors and Bioelectronics}, number = {Art. 113204}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0956-5663}, doi = {10.1016/j.bios.2021.113204}, year = {2021}, language = {en} } @article{YoshinobuSchoening2021, author = {Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef}, title = {Light-addressable potentiometric sensors (LAPS) for cell monitoring and biosensing}, series = {Current Opinion in Electrochemistry}, journal = {Current Opinion in Electrochemistry}, number = {In Press, Journal Pre-proof}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2451-9103}, doi = {10.1016/j.coelec.2021.100727}, year = {2021}, language = {en} } @article{GivanoudiCornelisRasschaertetal.2021, author = {Givanoudi, Stella and Cornelis, Peter and Rasschaert, Geertrui and Wackers, Gideon and Iken, Heiko and Rolka, David and Yongabi, Derick and Robbens, Johan and Sch{\"o}ning, Michael Josef and Heyndrickx, Marc and Wagner, Patrick}, title = {Selective Campylobacter detection and quantification in poultry: A sensor tool for detecting the cause of a common zoonosis at its source}, series = {Sensors and Actuators B: Chemical}, journal = {Sensors and Actuators B: Chemical}, number = {In Press, Journal Pre-proof}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2021.129484}, pages = {Article 129484}, year = {2021}, language = {en} } @article{VahidpourGuthmanArreolaetal.2022, author = {Vahidpour, Farnoosh and Guthman, Eric and Arreola, Julia and Alghazali, Yousef H. M. and Wagner, Torsten and Sch{\"o}ning, Michael Josef}, title = {Assessment of Various Process Parameters for Optimized Sterilization Conditions Using a Multi-Sensing Platform}, series = {Foods}, volume = {11}, journal = {Foods}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2304-8158}, doi = {10.3390/foods11050660}, pages = {Artikel 660}, year = {2022}, abstract = {In this study, an online multi-sensing platform was engineered to simultaneously evaluate various process parameters of food package sterilization using gaseous hydrogen peroxide (H₂O₂). The platform enabled the validation of critical aseptic parameters. In parallel, one series of microbiological count reduction tests was performed using highly resistant spores of B. atrophaeus DSM 675 to act as the reference method for sterility validation. By means of the multi-sensing platform together with microbiological tests, we examined sterilization process parameters to define the most effective conditions with regards to the highest spore kill rate necessary for aseptic packaging. As these parameters are mutually associated, a correlation between different factors was elaborated. The resulting correlation indicated the need for specific conditions regarding the applied H₂O₂ gas temperature, the gas flow and concentration, the relative humidity and the exposure time. Finally, the novel multi-sensing platform together with the mobile electronic readout setup allowed for the online and on-site monitoring of the sterilization process, selecting the best conditions for sterility and, at the same time, reducing the use of the time-consuming and costly microbiological tests that are currently used in the food package industry.}, language = {en} } @article{PoghossianWeldenBuniatyanetal.2021, author = {Poghossian, Arshak and Welden, Rene and Buniatyan, Vahe V. and Sch{\"o}ning, Michael Josef}, title = {An Array of On-Chip Integrated, Individually Addressable Capacitive Field-Effect Sensors with Control Gate: Design and Modelling}, series = {Sensors}, volume = {21}, journal = {Sensors}, number = {18}, publisher = {MDPI}, address = {Basel}, issn = {1424-8220}, doi = {10.3390/s21186161}, pages = {17}, year = {2021}, abstract = {The on-chip integration of multiple biochemical sensors based on field-effect electrolyte-insulator-semiconductor capacitors (EISCAP) is challenging due to technological difficulties in realization of electrically isolated EISCAPs on the same Si chip. In this work, we present a new simple design for an array of on-chip integrated, individually electrically addressable EISCAPs with an additional control gate (CG-EISCAP). The existence of the CG enables an addressable activation or deactivation of on-chip integrated individual CG-EISCAPs by simple electrical switching the CG of each sensor in various setups, and makes the new design capable for multianalyte detection without cross-talk effects between the sensors in the array. The new designed CG-EISCAP chip was modelled in so-called floating/short-circuited and floating/capacitively-coupled setups, and the corresponding electrical equivalent circuits were developed. In addition, the capacitance-voltage curves of the CG-EISCAP chip in different setups were simulated and compared with that of a single EISCAP sensor. Moreover, the sensitivity of the CG-EISCAP chip to surface potential changes induced by biochemical reactions was simulated and an impact of different parameters, such as gate voltage, insulator thickness and doping concentration in Si, on the sensitivity has been discussed.}, language = {en} } @article{VahidpourAlghazaliAkcaetal.2022, author = {Vahidpour, Farnoosh and Alghazali, Yousef and Akca, Sevilay and Hommes, Gregor and Sch{\"o}ning, Michael Josef}, title = {An Enzyme-Based Interdigitated Electrode-Type Biosensor for Detecting Low Concentrations of H₂O₂ Vapor/Aerosol}, series = {Chemosensors}, volume = {10}, journal = {Chemosensors}, number = {6}, publisher = {MDPI}, address = {Basel}, issn = {2227-9040}, doi = {10.3390/chemosensors10060202}, pages = {Arikel 202}, year = {2022}, abstract = {This work introduces a novel method for the detection of H₂O₂ vapor/aerosol of low concentrations, which is mainly applied in the sterilization of equipment in medical industry. Interdigitated electrode (IDE) structures have been fabricated by means of microfabrication techniques. A differential setup of IDEs was prepared, containing an active sensor element (active IDE) and a passive sensor element (passive IDE), where the former was immobilized with an enzymatic membrane of horseradish peroxidase that is selective towards H₂O₂. Changes in the IDEs' capacitance values (active sensor element versus passive sensor element) under H₂O₂ vapor/aerosol atmosphere proved the detection in the concentration range up to 630 ppm with a fast response time (<60 s). The influence of relative humidity was also tested with regard to the sensor signal, showing no cross-sensitivity. The repeatability assessment of the IDE biosensors confirmed their stable capacitive signal in eight subsequent cycles of exposure to H₂O₂ vapor/aerosol. Room-temperature detection of H₂O₂ vapor/aerosol with such miniaturized biosensors will allow a future three-dimensional, flexible mapping of aseptic chambers and help to evaluate sterilization assurance in medical industry.}, language = {en} } @article{PoghossianKarschuckWagneretal.2022, author = {Poghossian, Arshak and Karschuck, Tobias and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Field-Effect Capacitors Decorated with Ligand-Stabilized Gold Nanoparticles: Modeling and Experiments}, series = {Biosensors}, volume = {12}, journal = {Biosensors}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2079-6374}, doi = {10.3390/bios12050334}, pages = {Artikel 334}, year = {2022}, abstract = {Nanoparticles are recognized as highly attractive tunable materials for designing field-effect biosensors with enhanced performance. In this work, we present a theoretical model for electrolyte-insulator-semiconductor capacitors (EISCAP) decorated with ligand-stabilized charged gold nanoparticles. The charged AuNPs are taken into account as additional, nanometer-sized local gates. The capacitance-voltage (C-V) curves and constant-capacitance (ConCap) signals of the AuNP-decorated EISCAPs have been simulated. The impact of the AuNP coverage on the shift of the C-V curves and the ConCap signals was also studied experimentally on Al-p-Si-SiO₂ EISCAPs decorated with positively charged aminooctanethiol-capped AuNPs. In addition, the surface of the EISCAPs, modified with AuNPs, was characterized by scanning electron microscopy for different immobilization times of the nanoparticles.}, language = {en} } @article{KarschuckKaulenPoghossianetal.2021, author = {Karschuck, Tobias and Kaulen, Corinna and Poghossian, Arshak and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef}, title = {Gold nanoparticle-modified capacitive field-effect sensors: Studying the surface density of nanoparticles and coupling of charged polyelectrolyte macromolecules}, series = {Electrochemical Science Advances}, volume = {2}, journal = {Electrochemical Science Advances}, number = {5}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0938-5193}, doi = {10.1002/elsa.202100179}, pages = {10 Seiten}, year = {2021}, abstract = {The coupling of ligand-stabilized gold nanoparticles with field-effect devices offers new possibilities for label-free biosensing. In this work, we study the immobilization of aminooctanethiol-stabilized gold nanoparticles (AuAOTs) on the silicon dioxide surface of a capacitive field-effect sensor. The terminal amino group of the AuAOT is well suited for the functionalization with biomolecules. The attachment of the positively-charged AuAOTs on a capacitive field-effect sensor was detected by direct electrical readout using capacitance-voltage and constant capacitance measurements. With a higher particle density on the sensor surface, the measured signal change was correspondingly more pronounced. The results demonstrate the ability of capacitive field-effect sensors for the non-destructive quantitative validation of nanoparticle immobilization. In addition, the electrostatic binding of the polyanion polystyrene sulfonate to the AuAOT-modified sensor surface was studied as a model system for the label-free detection of charged macromolecules. Most likely, this approach can be transferred to the label-free detection of other charged molecules such as enzymes or antibodies.}, language = {en} } @article{BertzMolinnusSchoeningetal.2023, author = {Bertz, Morten and Molinnus, Denise and Sch{\"o}ning, Michael Josef and Homma, Takayuki}, title = {Real-time monitoring of H₂O₂ sterilization on individual bacillus atrophaeus spores by optical sensing with trapping Raman spectroscopy}, series = {Chemosensors}, volume = {8}, journal = {Chemosensors}, number = {11}, publisher = {MDPI}, address = {Basel}, issn = {2227-9040}, doi = {10.3390/chemosensors11080445}, pages = {Artikel 445}, year = {2023}, abstract = {Hydrogen peroxide (H₂O₂), a strong oxidizer, is a commonly used sterilization agent employed during aseptic food processing and medical applications. To assess the sterilization efficiency with H₂O₂, bacterial spores are common microbial systems due to their remarkable robustness against a wide variety of decontamination strategies. Despite their widespread use, there is, however, only little information about the detailed time-resolved mechanism underlying the oxidative spore death by H₂O₂. In this work, we investigate chemical and morphological changes of individual Bacillus atrophaeus spores undergoing oxidative damage using optical sensing with trapping Raman microscopy in real-time. The time-resolved experiments reveal that spore death involves two distinct phases: (i) an initial phase dominated by the fast release of dipicolinic acid (DPA), a major spore biomarker, which indicates the rupture of the spore's core; and (ii) the oxidation of the remaining spore material resulting in the subsequent fragmentation of the spores' coat. Simultaneous observation of the spore morphology by optical microscopy corroborates these mechanisms. The dependence of the onset of DPA release and the time constant of spore fragmentation on H₂O₂ shows that the formation of reactive oxygen species from H₂O₂ is the rate-limiting factor of oxidative spore death.}, language = {en} } @article{WendlandtKochBritzetal.2023, author = {Wendlandt, Tim and Koch, Claudia and Britz, Beate and Liedek, Anke and Schmidt, Nora and Werner, Stefan and Gleba, Yuri and Vahidpour, Farnoosh and Welden, Melanie and Poghossian, Arshak and Sch{\"o}ning, Michael Josef}, title = {Facile Purification and Use of Tobamoviral Nanocarriers for Antibody-Mediated Display of a Two-Enzyme System}, series = {Viruses}, volume = {9}, journal = {Viruses}, number = {15}, publisher = {MDPI}, address = {Basel}, issn = {1999-4915}, doi = {doi.org/10.3390/v15091951}, pages = {Artikel 1951}, year = {2023}, abstract = {Immunosorbent turnip vein clearing virus (TVCV) particles displaying the IgG-binding domains D and E of Staphylococcus aureus protein A (PA) on every coat protein (CP) subunit (TVCVPA) were purified from plants via optimized and new protocols. The latter used polyethylene glycol (PEG) raw precipitates, from which virions were selectively re-solubilized in reverse PEG concentration gradients. This procedure improved the integrity of both TVCVPA and the wild-type subgroup 3 tobamovirus. TVCVPA could be loaded with more than 500 IgGs per virion, which mediated the immunocapture of fluorescent dyes, GFP, and active enzymes. Bi-enzyme ensembles of cooperating glucose oxidase and horseradish peroxidase were tethered together on the TVCVPA carriers via a single antibody type, with one enzyme conjugated chemically to its Fc region, and the other one bound as a target, yielding synthetic multi-enzyme complexes. In microtiter plates, the TVCVPA-displayed sugar-sensing system possessed a considerably increased reusability upon repeated testing, compared to the IgG-bound enzyme pair in the absence of the virus. A high coverage of the viral adapters was also achieved on Ta2O5 sensor chip surfaces coated with a polyelectrolyte interlayer, as a prerequisite for durable TVCVPA-assisted electrochemical biosensing via modularly IgG-assembled sensor enzymes.}, language = {en} } @article{MoraisSumanSchoeningetal.2023, author = {Morais, Paulo V. and Suman, Pedro H. and Sch{\"o}ning, Michael Josef and Siqueira Junior, Jos{\´e} R. and Orlandi, Marcelo O.}, title = {Layer-by-layer film based on Sn₃O₄ nanobelts as sensing units to detect heavy metals using a capacitive field-effect sensor platform}, series = {Chemosensors}, volume = {11}, journal = {Chemosensors}, number = {8}, publisher = {MDPI}, address = {Basel}, issn = {2227-9040}, doi = {10.3390/chemosensors11080436}, pages = {Artikel 436}, year = {2023}, abstract = {Lead and nickel, as heavy metals, are still used in industrial processes, and are classified as "environmental health hazards" due to their toxicity and polluting potential. The detection of heavy metals can prevent environmental pollution at toxic levels that are critical to human health. In this sense, the electrolyte-insulator-semiconductor (EIS) field-effect sensor is an attractive sensing platform concerning the fabrication of reusable and robust sensors to detect such substances. This study is aimed to fabricate a sensing unit on an EIS device based on Sn₃O₄ nanobelts embedded in a polyelectrolyte matrix of polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) using the layer-by-layer (LbL) technique. The EIS-Sn₃O₄ sensor exhibited enhanced electrochemical performance for detecting Pb²⁺ and Ni²⁺ ions, revealing a higher affinity for Pb²⁺ ions, with sensitivities of ca. 25.8 mV/decade and 2.4 mV/decade, respectively. Such results indicate that Sn₃O₄ nanobelts can contemplate a feasible proof-of-concept capacitive field-effect sensor for heavy metal detection, envisaging other future studies focusing on environmental monitoring.}, language = {en} } @article{KarschuckSchmidtAchtsnichtetal.2023, author = {Karschuck, Tobias and Schmidt, Stefan and Achtsnicht, Stefan and Poghossian, Arshak and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Multiplexing system for automated characterization of a capacitive field-effect sensor array}, series = {Physica Status Solidi A}, volume = {220}, journal = {Physica Status Solidi A}, number = {22}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6300 (Print)}, doi = {10.1002/pssa.202300265}, pages = {7 Seiten}, year = {2023}, abstract = {In comparison to single-analyte devices, multiplexed systems for a multianalyte detection offer a reduced assay time and sample volume, low cost, and high throughput. Herein, a multiplexing platform for an automated quasi-simultaneous characterization of multiple (up to 16) capacitive field-effect sensors by the capacitive-voltage (C-V) and the constant-capacitance (ConCap) mode is presented. The sensors are mounted in a newly designed multicell arrangement with one common reference electrode and are electrically connected to the impedance analyzer via the base station. A Python script for the automated characterization of the sensors executes the user-defined measurement protocol. The developed multiplexing system is tested for pH measurements and the label-free detection of ligand-stabilized, charged gold nanoparticles.}, language = {en} } @article{OezsoyluAliaziziWagneretal.2024, author = {{\"O}zsoylu, Dua and Aliazizi, Fereshteh and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Template bacteria-free fabrication of surface imprinted polymer-based biosensor for E. coli detection using photolithographic mimics: Hacking bacterial adhesion}, series = {Biosensors and Bioelectronics}, volume = {261}, journal = {Biosensors and Bioelectronics}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-4235 (eISSN)}, doi = {10.1016/j.bios.2024.116491}, pages = {11 Seiten}, year = {2024}, abstract = {As one class of molecular imprinted polymers (MIPs), surface imprinted polymer (SIP)-based biosensors show great potential in direct whole-bacteria detection. Micro-contact imprinting, that involves stamping the template bacteria immobilized on a substrate into a pre-polymerized polymer matrix, is the most straightforward and prominent method to obtain SIP-based biosensors. However, the major drawbacks of the method arise from the requirement for fresh template bacteria and often non-reproducible bacteria distribution on the stamp substrate. Herein, we developed a positive master stamp containing photolithographic mimics of the template bacteria (E. coli) enabling reproducible fabrication of biomimetic SIP-based biosensors without the need for the "real" bacteria cells. By using atomic force and scanning electron microscopy imaging techniques, respectively, the E. coli-capturing ability of the SIP samples was tested, and compared with non-imprinted polymer (NIP)-based samples and control SIP samples, in which the cavity geometry does not match with E. coli cells. It was revealed that the presence of the biomimetic E. coli imprints with a specifically designed geometry increases the sensor E. coli-capturing ability by an "imprinting factor" of about 3. These findings show the importance of geometry-guided physical recognition in bacterial detection using SIP-based biosensors. In addition, this imprinting strategy was employed to interdigitated electrodes and QCM (quartz crystal microbalance) chips. E. coli detection performance of the sensors was demonstrated with electrochemical impedance spectroscopy (EIS) and QCM measurements with dissipation monitoring technique (QCM-D).}, language = {en} } @article{YoshinobuMiyamotoWagneretal.2024, author = {Yoshinobu, Tatsuo and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef}, title = {Field-effect sensors combined with the scanned light pulse technique: from artificial olfactory images to chemical imaging technologies}, series = {Chemosensors}, volume = {12}, journal = {Chemosensors}, number = {2}, publisher = {MDPI}, address = {Basel}, issn = {2227-9040}, doi = {10.3390/chemosensors12020020}, pages = {Artikel 20}, year = {2024}, abstract = {The artificial olfactory image was proposed by Lundstr{\"o}m et al. in 1991 as a new strategy for an electronic nose system which generated a two-dimensional mapping to be interpreted as a fingerprint of the detected gas species. The potential distribution generated by the catalytic metals integrated into a semiconductor field-effect structure was read as a photocurrent signal generated by scanning light pulses. The impact of the proposed technology spread beyond gas sensing, inspiring the development of various imaging modalities based on the light addressing of field-effect structures to obtain spatial maps of pH distribution, ions, molecules, and impedance, and these modalities have been applied in both biological and non-biological systems. These light-addressing technologies have been further developed to realize the position control of a faradaic current on the electrode surface for localized electrochemical reactions and amperometric measurements, as well as the actuation of liquids in microfluidic devices.}, language = {en} } @article{BertzSchoeningMolinnusetal.2024, author = {Bertz, Morten and Sch{\"o}ning, Michael Josef and Molinnus, Denise and Homma, Takayuki}, title = {Influence of temperature, light, and H₂O₂ concentration on microbial spore inactivation: in-situ Raman spectroscopy combined with optical trapping}, series = {Physica status solidi (a) applications and materials science}, journal = {Physica status solidi (a) applications and materials science}, number = {Early View}, publisher = {Wiley-VCH}, address = {Berlin}, issn = {1862-6319 (Online)}, doi = {10.1002/pssa.202300866}, pages = {8 Seiten}, year = {2024}, abstract = {To gain insight on chemical sterilization processes, the influence of temperature (up to 70 °C), intense green light, and hydrogen peroxide (H₂O₂) concentration (up to 30\% in aqueous solution) on microbial spore inactivation is evaluated by in-situ Raman spectroscopy with an optical trap. Bacillus atrophaeus is utilized as a model organism. Individual spores are isolated and their chemical makeup is monitored under dynamically changing conditions (temperature, light, and H₂O₂ concentration) to mimic industrially relevant process parameters for sterilization in the field of aseptic food processing. While isolated spores in water are highly stable, even at elevated temperatures of 70 °C, exposure to H₂O₂ leads to a loss of spore integrity characterized by the release of the key spore biomarker dipicolinic acid (DPA) in a concentration-dependent manner, which indicates damage to the inner membrane of the spore. Intensive light or heat, both of which accelerate the decomposition of H₂O₂ into reactive oxygen species (ROS), drastically shorten the spore lifetime, suggesting the formation of ROS as a rate-limiting step during sterilization. It is concluded that Raman spectroscopy can deliver mechanistic insight into the mode of action of H₂O₂-based sterilization and reveal the individual contributions of different sterilization methods acting in tandem.}, language = {en} } @article{KarschuckPoghossianSeretal.2024, author = {Karschuck, Tobias and Poghossian, Arshak and Ser, Joey and Tsokolakyan, Astghik and Achtsnicht, Stefan and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Capacitive model of enzyme-modified field-effect biosensors: Impact of enzyme coverage}, series = {Sensors and Actuators B: Chemical}, volume = {408}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005 (Print)}, doi = {10.1016/j.snb.2024.135530}, pages = {12 Seiten}, year = {2024}, abstract = {Electrolyte-insulator-semiconductor capacitors (EISCAP) belong to field-effect sensors having an attractive transducer architecture for constructing various biochemical sensors. In this study, a capacitive model of enzyme-modified EISCAPs has been developed and the impact of the surface coverage of immobilized enzymes on its capacitance-voltage and constant-capacitance characteristics was studied theoretically and experimentally. The used multicell arrangement enables a multiplexed electrochemical characterization of up to sixteen EISCAPs. Different enzyme coverages have been achieved by means of parallel electrical connection of bare and enzyme-covered single EISCAPs in diverse combinations. As predicted by the model, with increasing the enzyme coverage, both the shift of capacitance-voltage curves and the amplitude of the constant-capacitance signal increase, resulting in an enhancement of analyte sensitivity of the EISCAP biosensor. In addition, the capability of the multicell arrangement with multi-enzyme covered EISCAPs for sequentially detecting multianalytes (penicillin and urea) utilizing the enzymes penicillinase and urease has been experimentally demonstrated and discussed.}, language = {en} }