TY - JOUR A1 - Liebherr, Raphaela B. A1 - Hutterer, Albert A1 - Mickert, Matthias J. A1 - Vogl, Franziska C. A1 - Beutner, Andrea A1 - Lechner, Alfred A1 - Hummel, Helmut A1 - Gorris, Hans H. T1 - Three-in-one enzyme assay based on single molecule detection in femtoliter arrays JF - Analytical and bioanalytical chemistry N2 - Large arrays of femtoliter-sized chambers are important tools for single molecule research as well as bioanalytical applications. We have optimized the design and fabrication of two array types consisting of 250 × 250 (62 500) femtoliter chambers either by surface etching of fused silica slides or by polydimethylsiloxane (PDMS) molding. Highly diluted solutions of β-galactosidase were enclosed in such arrays to monitor the fluorogenic reactions of hundreds of individual enzyme molecules in parallel by wide-field fluorescence microscopy. An efficient mechanical sealing procedure was developed to prevent diffusion of the fluorescent reaction product out of the chambers. Different approaches for minimizing non-specific surface adsorption were explored. The signal acquisition was optimized to grant both a large field of view and an efficient signal acquisition from each femtoliter chamber. The optimized femtoliter array has enabled a three-in-one enzyme assay system: First, the concentration of active enzyme can be determined in a digital way by counting fluorescent chambers in the array. Second, the activity of the enzyme bulk solution is given by averaging many individual substrate turnover rates without the need for knowing the exact enzyme concentration. Third-unlike conventional enzyme assays-the distribution of individual substrate turnover rates yields insight into the conformational heterogeneity in an enzyme population. The substrate turnover rates of single β-galactosidase molecules were found to be broadly distributed and independent of the type of femtoliter array. In general, both types of femtoliter arrays are highly sensitive platforms for enzyme analysis at the single molecule level and yield consistent results. KW - ARRAYS KW - Digital concentration readout KW - Enzyme kinetics KW - Fluorescence microscopy KW - Single molecule detection Y1 - 2015 U6 - https://doi.org/10.1007/s00216-015-8910-0 VL - 407 IS - 24 SP - 7443 EP - 7452 PB - Springer ER - TY - JOUR A1 - Hutterer, Albert A1 - Bauhuber, Michael A1 - Hummel, Helmut A1 - Lechner, Alfred T1 - Real-time analyses of metal contaminations in the ppb-range JF - Solid State Phenomena N2 - In high-tech processing even smallest concentrations of metal ions in process media are of the utmost significance because they cause expensive production failures. Currently, cost-intensive equipment, special trained staff and time consuming analyses are necessary to detect these contaminations in order to avoid failures. The Centers of Excellence Nanochem and Sensorics at the University of Applied Sciences Regensburg (owner of patent PCT/EP2010/064833) and their industrial partner Micro-Epsilon GmbH are developing a new miniaturized measurement device which allows cost-effective real-time analysis of fluidic media for the first time. The system is fully automated and can be directly connected to wet-etch benches. Hence it allows continuous real-time surveillance of metal contaminations in the ppb-range through absorption spectroscopy in process media. For this purpose a very small sample amount of the process medium and a specific complexing agent are mixed together. This leads to an increase in the molar extinction coefficients and though even smallest contaminations become visible. The main parts of our development are the simulation of the different system components, their production and chemical analyses with the evaluation model. KW - Absorption KW - Analysis KW - Complexing Agent KW - Light Guidance KW - Liquid-Core Waveguide KW - Metal Ions KW - Online Measurement KW - Real-Time KW - Total Internal Reflection Y1 - 2013 U6 - https://doi.org/10.4028/www.scientific.net/SSP.195 VL - 195 SP - 269 EP - 273 PB - Trans Tech Publications ER - TY - JOUR A1 - Beimler, Josef A1 - Leißl, Caroline A1 - Ebner, Lena A1 - Elsner, Michael A1 - Mühlbauer, Gerhard A1 - Kohlert, Dieter A1 - Schubert, Martin J. W. A1 - Weiß, Andreas P. A1 - Sterner, Michael A1 - Raith, Thomas A1 - Afranseder, Martin A1 - Krapf, Tobias A1 - Mottok, Jürgen A1 - Siemers, Christian A1 - Großmann, Benjamin A1 - Höcherl, Johannes A1 - Schlegl, Thomas A1 - Schneider, Ralph A1 - Milaev, Johannes A1 - Rampelt, Christina A1 - Roduner, Christian A1 - Glowa, Christoph A1 - Bachl, Christoph A1 - Schliekmann, Claus A1 - Gnan, Alfons A1 - Grill, Martin A1 - Ruhland, Karl A1 - Piehler, Thomas A1 - Friers, Daniel A1 - Wels, Harald A1 - Pflug, Kenny A1 - Kucera, Markus A1 - Waas, Thomas A1 - Schlachetzki, Felix A1 - Boy, Sandra A1 - Pemmerl, Josef A1 - Leis, Alexander A1 - Welsch, Andreas F.X. A1 - Graf, Franz A1 - Zenger, Gerhard A1 - Volbert, Klaus A1 - Waas, Thomas A1 - Scherzinger, Stefanie A1 - Klettke, Meike A1 - Störl, Uta A1 - Heyl, C. A1 - Boldenko, A. A1 - Monkman, Gareth J. A1 - Kujat, Richard A1 - Briem, Ulrich A1 - Hierl, Stefan A1 - Talbot, Sebastian A1 - Schmailzl, Anton A1 - Ławrowski, Robert Damian A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Dams, Florian A1 - Schreiner, Rupert A1 - Valentino, Piergiorgio A1 - Romano, Marco A1 - Ehrlich, Ingo A1 - Furgiuele, Franco A1 - Gebbeken, Norbert A1 - Eisenried, Michael A1 - Jungbauer, Bastian A1 - Hutterer, Albert A1 - Bauhuber, Michael A1 - Mikrievskij, Andreas A1 - Argauer, Monika A1 - Hummel, Helmut A1 - Lechner, Alfred A1 - Liebetruth, Thomas A1 - Schumm, Michael A1 - Joseph, Saskia A1 - Reschke, Michael A1 - Soska, Alexander A1 - Schroll-Decker, Irmgard A1 - Putzer, Michael A1 - Rasmussen, John A1 - Dendorfer, Sebastian A1 - Weber, Tim A1 - Al-Munajjed, Amir Andreas A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias A1 - Haug, Sonja A1 - Rudolph, Clarissa A1 - Zeitler, Annika A1 - Schaubeck, Simon A1 - Steffens, Oliver A1 - Rechenauer, Christian A1 - Schulz-Brize, Thekla A1 - Fleischmann, Florian A1 - Kusterle, Wolfgang A1 - Beer, Anne A1 - Wagner, Bernd A1 - Neidhart, Thomas ED - Baier, Wolfgang T1 - Forschungsbericht 2013 T3 - Forschungsberichte der OTH Regensburg - 2013 Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-7990 CY - Regensburg ER -