@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} } @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} } @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{SchoeningBronderWuetal.2017, author = {Sch{\"o}ning, Michael Josef and Bronder, Thomas and Wu, Chunsheng and Scheja, Sabrina and Jessing, Max and Metzger-Boddien, Christoph and Keusgen, Michael and Poghossian, Arshak}, title = {Label-Free DNA Detection with Capacitive Field-Effect Devices—Challenges and Opportunities}, series = {Proceedings}, volume = {1}, journal = {Proceedings}, number = {8}, publisher = {MDPI}, address = {Basel}, issn = {2504-3900}, doi = {10.3390/proceedings1080719}, pages = {Artikel 719}, year = {2017}, abstract = {Field-effect EIS (electrolyte-insulator-semiconductor) sensors modified with a positively charged weak polyelectrolyte layer have been applied for the electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge. The EIS sensors are able to detect the existence of target DNA amplicons in PCR (polymerase chain reaction) samples and thus, can be used as tool for a quick verification of DNA amplification and the successful PCR process. Due to their miniaturized setup, compatibility with advanced micro- and nanotechnologies, and ability to detect biomolecules by their intrinsic molecular charge, those sensors can serve as possible platform for the development of label-free DNA chips. Possible application fields as well as challenges and limitations will be discussed.}, language = {en} } @article{MuribYeapEurlingsetal.2016, author = {Murib, M. S. and Yeap, W. S. and Eurlings, Y. and Grinsven, B. van and Boyen, H.-G. and Conings, B. and Michiels, L. and Ameloot, M. and Carleer, R. and Warmer, J. and Kaul, P. and Haenen, K. and Sch{\"o}ning, Michael Josef and Ceuninck, W. de and Wagner, P.}, title = {Heat-transfer based characterization of DNA on synthetic sapphire chips}, series = {Sensors and Actuators B: Chemical}, volume = {230}, journal = {Sensors and Actuators B: Chemical}, number = {230}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2016.02.027}, pages = {260 -- 271}, year = {2016}, abstract = {In this study, we show that synthetic sapphire (Al₂O₃), an established implant material, can also serve as a platform material for biosensors comparable to nanocrystalline diamond. Sapphire chips, beads, and powder were first modified with (3-aminopropyl) triethoxysilane (APTES), followed by succinic anhydride (SA), and finally single-stranded probe DNA was EDC coupled to the functionalized layer. The presence of the APTES-SA layer on sapphire powders was confirmed by thermogravimetric analyis and Fourier-transform infrared spectroscopy. Using planar sapphire chips as substrates and X-ray photoelectron spectroscopy (XPS) as surface-sensitive tool, the sequence of individual layers was analyzed with respect to their chemical state, enabling the quantification of areal densities of the involved molecular units. Fluorescence microscopy was used to demonstrate the hybridization of fluorescently tagged target DNA to the probe DNA, including denaturation- and re-hybridization experiments. Due to its high thermal conductivity, synthetic sapphire is especially suitable as a chip material for the heat-transfer method, which was employed to distinguish complementary- and non-complementary DNA duplexes containing single-nucleotide polymorphisms. These results indicate that it is possible to detect mutations electronically with a chemically resilient and electrically insulating chip material.}, language = {en} } @article{HamadBilattoAdlyetal.2016, author = {Hamad, E. M. and Bilatto, S. E. R. and Adly, N. Y. and Correa, D. S. and Wolfrum, B. and Sch{\"o}ning, Michael Josef and Offenh{\"a}usser, A. and Yakushenko, A.}, title = {Inkjet printing of UV-curable adhesive and dielectric inks for microfluidic devices}, series = {Lab on a Chip}, volume = {16}, journal = {Lab on a Chip}, number = {1}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1473-0189}, doi = {10.1039/C5LC01195G}, pages = {70 -- 74}, year = {2016}, abstract = {Bonding of polymer-based microfluidics to polymer substrates still poses a challenge for Lab-On-a-Chip applications. Especially, when sensing elements are incorporated, patterned deposition of adhesives with curing at ambient conditions is required. Here, we demonstrate a fabrication method for fully printed microfluidic systems with sensing elements using inkjet and stereolithographic 3D-printing.}, language = {en} } @article{DantismTakenagaWagneretal.2016, author = {Dantism, Shahriar and Takenaga, Shoko and Wagner, Patrick and Wagner, Torsten and Sch{\"o}ning, Michael Josef}, title = {Determination of the extracellular acidification of Escherichia coli K12 with a multi-​chamber-​based LAPS system}, series = {Physica status solidi (a)}, volume = {213}, journal = {Physica status solidi (a)}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6300}, doi = {10.1002/pssa.201533043}, pages = {1479 -- 1485}, year = {2016}, abstract = {On-line monitoring of the metabolic activity of microorganisms involved in intermediate stages of biogas production plays an important role to avoid undesirable "down times" during the biogas production. In order to control this process, an on-chip differential measuring system based on the light-addressable potentiometric sensor (LAPS) principle combined with a 3D-printed multi-chamber structure has been realized. As a test microorganism, Escherichia coli K12 (E. coli K12) were used for cell-based measurements. Multi-chamber structures were developed to determine the metabolic activity of E. coli K12 in suspension for a different number of cells, responding to the addition of a constant or variable amount of glucose concentrations, enabling differential and simultaneous measurements.}, language = {en} } @article{BreuerRaueStrobeletal.2016, author = {Breuer, Lars and Raue, Markus and Strobel, M. and Mang, Thomas and Sch{\"o}ning, Michael Josef and Thoelen, R. and Wagner, Torsten}, title = {Hydrogels with incorporated graphene oxide as light-addressable actuator materials for cell culture environments in lab-on-chip systems}, series = {Physica status solidi (a)}, volume = {213}, journal = {Physica status solidi (a)}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6300}, doi = {10.1002/pssa.201533056}, pages = {1520 -- 1525}, year = {2016}, abstract = {Abstractauthoren Graphene oxide (GO) nanoparticles were incorporated in temperature-sensitive Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. The nanoparticles increase the light absorption and convert light energy into heat efficiently. Thus, the hydrogels with GO can be stimulated spatially resolved by illumination as it was demonstrated by IR thermography. The temporal progression of the temperature maximum was detected for different concentrations of GO within the polymer network. Furthermore, the compatibility of PNIPAAm hydrogels with GO and cell cultures was investigated. For this purpose, culture medium was incubated with hydrogels containing GO and the viability and morphology of chinese hamster ovary (CHO) cells was examined after several days of culturing in presence of this medium.}, language = {en} } @inproceedings{KasperSchiffelsKrafftetal.2016, author = {Kasper, Katharina and Schiffels, Johannes and Krafft, Simone and Kuperjans, Isabel and Elbers, Gereon and Selmer, Thorsten}, title = {Biogas Production on Demand Regulated by Butyric Acid Addition}, series = {IOP Conference Series: Earth and Environmental Science. Bd. 32}, volume = {32}, booktitle = {IOP Conference Series: Earth and Environmental Science. Bd. 32}, issn = {1755-1315}, doi = {10.1088/1755-1315/32/1/012009}, pages = {012009/1 -- 012009/4}, year = {2016}, language = {en} }