TY - GEN A1 - Wilke, Marco A1 - Röder, Bettina A1 - Paul, Martin A1 - Weller, Michael G. T1 - Sintered Glass Monoliths as New Supports for Affinity Columns N2 - A novel stationary phase for affinity separations is presented. This material is based on sintered borosilicate glass readily available as semi-finished filter plates with defined porosity and surface area. The material shows fast binding kinetics and excellent long-term stability under real application conditions due to lacking macropores and high mechanical rigidity. The glass surface can be easily modified with standard organosilane chemistry to immobilize selective binders or other molecules used for biointeraction. In this paper, the manufacturing of the columns and their respective column holders by 3D printing is shown in detail. The model system protein A/IgG was chosen as an example to examine the properties of such monolithic columns under realistic application conditions. Several specifications, such as (dynamic) IgG capacity, pressure stability, long-term performance, productivity, non-specific binding, and peak shape, are presented. It could be shown that due to the very high separation speed, 250 mg antibody per hour and column can be collected, which surpasses the productivity of most standard columns of the same size. The total IgG capacity of the shown columns is around 4 mg (5.5 mg/mL), which is sufficient for most tasks in research laboratories. The cycle time of an IgG separation can be less than 1 minute. Due to the glass material's excellent pressure resistance, these columns are compatible with standard HPLC systems. This is usually not the case with standard affinity columns, limited to manual use or application in low-pressure systems. The use of a standard HPLC system also improves the ability for automation, which enables the purification of hundreds of cell supernatants in one day. The sharp peak shape of the elution leads to an enrichment effect, which might increase the concentration of IgG by a factor of 3. The final concentration of IgG can be around 7.5 mg/mL without the need for an additional nanofiltration step. The purity of the IgG was > 95% in one step and nearly 99% with a second polishing run. KW - Affinity Chromatography KW - Glass KW - Purification KW - Antibodies KW - Solid support KW - HPLC KW - FPLC KW - Separation PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-529117 SP - 1 PB - MDPI CY - Basel AN - OPUS4-52911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Paul, Martin A1 - Tannenberg, Robert A1 - Tscheuschner, Georg A1 - Wilke, Marco A1 - Weller, Michael G. T1 - Cocaine Detection by a Laser-induced Immunofluorometric Biosensor N2 - The trafficking of illegal drugs by criminal networks at borders, harbors, or airports is an increasing issue in public health as these routes ensure the main supply of illegal drugs. The prevention of drug smuggling, including the installation of scanners and other analytical devices to detect ultra-small traces of drugs within a reasonable time frame, remains a challenge. The presented immunosensor is based on a monolithic affinity column with a large excess of immobilized hapten, which traps fluorescently labeled antibodies as long as the analyte cocaine is absent. In the presence of the drug, some binding sites of the antibody will be blocked, which leads to an immediate breakthrough of the labeled protein, detectable by highly sensitive laser-induced fluorescence with the help of a Peltier-cooled complementary metal-oxide-semiconductor (CMOS) camera. Liquid handling is performed with high-precision syringe pumps and microfluidic chip-based mixing devices and flow cells. The biosensor achieved limits of detection of 23 pM (7 ppt) of cocaine with a response time of 90 seconds and a total assay time below 3 minutes. With surface wipe sampling, the biosensor was able to detect 300 pg of cocaine. This immunosensor belongs to the most sensitive and fastest detectors for cocaine and offers near-continuous analyte measurement. KW - Drug search KW - Customs KW - Confiscation KW - Border surveillance KW - Narcotics KW - International drug trade KW - Drug trafficking KW - Illicit drug KW - Immunosensor KW - Antibodies KW - Detection PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-529951 SP - 1 PB - MDPI CY - Basel AN - OPUS4-52995 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Steglich, P. A1 - Rabus, D. G. A1 - Sada, C. A1 - Paul, Martin A1 - Weller, Michael G. A1 - Mai, C. A1 - Mai, A. T1 - Silicon Photonic Micro-Ring Resonators for Chemical and Biological Sensing: A Tutorial N2 - Silicon photonic micro-ring resonators (MRR) developed on the silicon-on-insulator (SOI) platform, owing to their high sensitivity and small footprint, show great potential for many chemical and biological sensing applications such as label-free detection in environmental monitoring, biomedical engineering, and food analysis. In this tutorial, we provide the theoretical background and give design guidelines for SOI-based MRR as well as examples of surface functionalization procedures for label-free detection of molecules. After introducing the advantages and perspectives of MRR, fundamentals of MRR are described in detail, followed by an introduction to the fabrication methods, which are based on a complementary metal-oxide semiconductor (CMOS) technology. Optimization of MRR for chemical and biological sensing is provided, with special emphasis on the optimization of waveguide geometry. At this point, the difference between chemical bulk sensing and label-free surface sensing is explained, and definitions like waveguide sensitivity, ring sensitivity, overall sensitivity as well as the limit of detection (LoD) of MRR are introduced. Further, we show and explain chemical bulk sensing of sodium chloride (NaCl) in water and provide a recipe for label-free surface sensing. KW - Lab on a chip KW - Biosensor KW - Cmos KW - Silanization KW - Surface derivatization KW - Evanescent wave PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-529360 SP - 1 EP - 18 PB - IEEE CY - Piscataway Township AN - OPUS4-52936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hothan, Sascha A1 - Häßler, Dustin T1 - Über die Entwicklung von Anwendungsregeln für reaktive Brandschutzsysteme auf Stahlzuggliedern N2 - Der vorliegende Beitrag stellt den Entwicklungsstand von Anwendungsregeln für reaktive Brandschutzsysteme auf Stahlzuggliedern zusammenfassend dar. Dabei wird insbesondere auf die jüngsten Veränderungen in den normativen Grundlagen und bauaufsichtlichen Regelungen eingegangen und im Hinblick auf Sicherheitsaspekte bewertet. Die Verringerung der Teilsicherheit für den Bauteilwiderstand nicht stabilitätsgefährdeter Bauteile im Regelwerk für die Kaltbemessung von Stahltragwerken ist hier als besonders kritisch anzusehen, da hierdurch ein systematisches Sicherheitsdefizit für den Brandfall verursacht wird. Weiterhin werden neuste Forschungsergebnisse bei der Entwicklung von Bewertungsregeln von reaktiven Brandschutzsystemen auf Vollkreisprofilen unter Zugbeanspruchung vorgestellt und diskutiert. Die Untersuchungen behandeln die Fragestellung, inwieweit Prüfungen mit Zugbeanspruchungen an Kreisvollprofilen erforderlich sein werden. KW - Stahlkonstruktion KW - Brandschutz KW - Reaktive Brandschutzsysteme KW - Zugglieder PY - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-307949 SP - 141 EP - 148 PB - Institut für Stahlbau / Leibniz Universität Hannover CY - Hannover AN - OPUS4-30794 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Unger, Wolfgang T1 - Non-destructive surface measurements N2 - Materials and chemical producers require detailed knowledge of surface chemistry for research into new products. One way to understand a surface without damaging it is to bombard it with an electron beam, causing its atoms to emit characteristic X-rays enabling identification. The measurement of these must be precise as many elements emissions are close in energy – traceable reference materials will ensure instruments using this technique are stable and accurate. KW - Metrology KW - EDS KW - EDX PY - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-388647 UR - http://www.euramet.org/metrology-for-societys-challenges/metrology-for-industry/impact-case-studies-emrp-industry-theme/ SP - 1 EP - 2 CY - Teddington AN - OPUS4-38864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Paul, Martin A1 - Weller, Michael G. T1 - Antibody Screening by Microarray Technology – Direct Identification of Selective High-Affinity Clones N2 - The primary screening of hybridoma cells is a time-critical and laborious step during the development of monoclonal antibodies. Often critical errors occur in this phase, which supports the notion that the generation of monoclonal antibodies with hybridoma technology is difficult to control and hence a risky venture. We think that it is crucial to improve the screening process to eliminate most of the immanent deficits of the conventional approach. With this new microarray-based procedure, several advances could be achieved: Selectivity for excellent binders, high throughput, reproducible signals, avoidance of misleading avidity (multivalency) effects, and simultaneous performance of competition experiments. The latter can directly be used to select clones of desired cross-reactivity properties. In this paper, a model system with two excellent clones against carbamazepine, two weak clones and blank supernatant has been designed to examine the effectiveness of the new system. The excellent clones could be detected largely independent of the IgG concentration, which is unknown during the clone screening since the determination and subsequent adjustment of the antibody concentration is not possible in most cases. Furthermore, in this approach, the enrichment, isolation, and purification of IgG for characterization is not necessary. Raw cell culture supernatant can be used directly, even when fetal calf serum (FCS) or other complex media had been used. In addition, an improved method for the oriented antibody-immobilization on epoxy-silanized slides is presented. Based on the results of this model system, we conclude that this approach should be preferable to most other protocols leading to many of false positives, causing expensive and lengthy confirmation steps to weed out the poor clones. KW - Hybridoma KW - Monoclonal Antibodies KW - Clones KW - Competitive Immunoassay KW - Hapten Immunoassay KW - False Positives PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-506621 SN - 2310-287X SP - 1 EP - 17 PB - MDPI CY - Basel AN - OPUS4-50662 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Tscheuschner, Georg A1 - Schwaar, Timm A1 - Weller, Michael G. T1 - Fast Confirmation of Antibody Identity by MALDI-TOF-MS Fingerprints N2 - Thousands of antibodies for diagnostic and other analytical purposes are on the market. However, it is often difficult to identify duplicates, reagent changes, and to assign the correct original publications to an antibody. This slows down scientific progress and might even be a cause of irreproducible research and a waste of resources. Recently, activities were started to suggest the sole use of recombinant antibodies in combination with the open communication of their sequence. In this case, such uncertainties should be eliminated. Unfortunately, this approach seems to be rather a long-term vision since the development and manufacturing of recombinant antibodies remain quite expensive in the foreseeable future. Also, nearly all commercial antibody suppliers may be reluctant to publish the sequence of their antibodies, since they fear counterfeiting. De-novo sequencing of antibodies is also not feasible today for a reagent user without access to the hybridoma clone. Nevertheless, it seems to be crucial for any scientist to have the opportunity to identify an antibody undoubtedly to guarantee the traceability of any research activity using antibodies from a third party as a tool. For this purpose, we developed a method for the identification of antibodies based on a MALDI-TOF-MS fingerprint. To circumvent lengthy denaturation, reduction, alkylation, and enzymatic digestion steps, the fragmentation was performed with a simple formic acid hydrolysis step. Eighty-nine unknown monoclonal antibodies were used for this study to examine the feasibility of this approach. Although the molecular assignment of peaks was rarely possible, antibodies could be easily recognized in a blinded test, simply from their mass-spectral fingerprint. A general protocol is given, which could be used without any optimization to generate fingerprints for a database. We want to propose that in most scientific projects relying critically on antibody reagents, such a fingerprint should be established to prove and document the identity of the used antibodies and to assign a specific reagent to a datasheet of a commercial supplier, a public database record or an antibody ID. KW - Reproducibility KW - Quality Control KW - Traceability KW - Diagnostics KW - ELISA KW - Immunoassay PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-506590 SN - 2310-287X SP - 1 EP - 17 PB - MDPI CY - Basel AN - OPUS4-50659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Weller, Michael G. T1 - Referee Report 06 March 2017 N2 - This article is a valuable and welcome contribution to the ongoing discussion of antibody quality. The suggestion of a two-tier approach is helpful to distinguish between simple descriptive data and the validation of an antibody for a specified application. KW - Antibody KW - Validation PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-393333 UR - https://f1000research.com/articles/6-161/v1#referee-response-20349 SN - 2046-1402 SP - 6 EP - 7 PB - F1000 Research Ltd. CY - London AN - OPUS4-39333 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Dietrich, P. A1 - Thissen, A. A1 - Kulak, N. A1 - Kjaervik, Marit A1 - Unger, Wolfgang T1 - XPS surface chemical analysis of aqueous solutions with EnviroESCA N2 - Water and aqueous reagents are essential in any biological process or system. But apart from a few special low vapor-pressure cases, liquids have not been accessible to any technique requiring UHV conditions. EnviroESCA opens up this exciting field of applications. In this paper first results from water based samples are presented as a proof of concept to demonstrate the special capabilities of EnviroESCA analyzing liquid samples. The following solutions were investigated under near ambient pressure conditions: i.) water, ii.) brine, iii.) an oil in water dispersion, iv.) aqueous iron(II) sulfate heptahydrate, and v.) a suspension of nano silver particles in water. KW - Surface Analysis KW - Near Ambient Pressure XPS KW - Aqueous Solutions PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-394603 UR - http://www.enviro.specs.de/cms/upload/bilder/EnviroESCA/Applications/Liquids/Application-Note_EnviroESCA_Aqueous_Solutions.pdf N1 - BAM Mitarbeiter Beitrag im Acknowledgement definiert. IS - #000394 SP - 1 PB - SPECS CY - Berlin AN - OPUS4-39460 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Weller, Michael G. T1 - Interview with Dr Michael G. Weller N2 - This author interview is by Dr Michael G. Weller, Head of Division 1.5 Protein Analysis at Federal Institute for Materials Research and Testing (BAM). BAM (www.bam.de/en) is a senior scientific and technical institute with responsibility to the German Federal Ministry for Economic Affairs and Energy. Dr Weller's review paper, Quality issues of research antibodies is available for download in Analytical Chemistry Insights. KW - Antibodies KW - Quality KW - Reproducibility PY - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-392326 UR - http://insights.sagepub.com/la_press_news.php?pa=view&news_item_id=4025 SP - 1 PB - SAGE CY - London AN - OPUS4-39232 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Lehmann, Jens A1 - Burkert, Andreas T1 - KorroPad - Beurteilung der Korrosionsbeständigkeit von Oberflächen nichtrostender Stähle N2 - Mit dem KorroPad Verfahren ist es dem Anwender möglich den Zustand der Passivschicht nichtrostender Stähle auf sehr einfache und schnelle Weise einschätzen zu können. Das Verfahren eignet sich dazu, den Grad der Passivität in Abhängigkeit der Umgebungsbedingungen und der Zeit nachzuvollziehen. Dies ermöglicht dem Anwender und Verarbeiter von nichtrostenden Stählen, die Lagerungsbedingungen und -zeiten einer frisch bearbeiteten Stahloberfläche zu ermitteln, welche für die Ausbildung einer stabilen Passivschicht notwendig sind, bevor diese risikoarm eingesetzt werden kann. Wie die hier dargestellten Beispiele und auch weitere zahlreiche praktische Anwendungen gezeigt haben, eignet sich das KorroPad ebenfalls für die Identifikation kritischer Prozessparameter bei der Verarbeitung nichtrostender Stähle. Mit dem Verfahren lassen sich viele rozessbedingte Einflussfaktoren auf die Oberflächengüte wie auch auf den Werkstoff charakterisieren. Aufgrund der schnellen und einfachen Auswertung der Prüfergebnisse können positive wie auch negative Veränderungen hinsichtlich der Passivschichtstabilität zügig erkannt werden. Dies ermöglicht es dem Anwender schnell zu reagieren, um kritische Einflüsse zu korrigieren und um eine Optimierung von Inhouse-Prozessen durchzuführen. Weitere Einsatzgebiete sind im Bereich der Wareneingangs- und/oder Warenausgangskontrolle denkbar, überall wo es um die Frage der Passivschichtstabilität einer nichtrostenden Stahloberfläche geht. KW - Korrosionstest KW - nichtrostender Stahl KW - Edelstahl Rostfrei PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-397049 UR - http://www.ndt.net/article/dgzfp-bau-2016/papers/16.pdf SN - 1435-4934 VL - 22 IS - 4 SP - Artikel 16 PB - NDT.net CY - Bad Breising AN - OPUS4-39704 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schroeder, Barbara A1 - Le Xuan, Hoa A1 - Völzke, Jule L. A1 - Weller, Michael G. T1 - Preactivation crosslinking – An efficient method for the oriented immobilization of antibodies N2 - Crosslinking of proteins for their irreversible immobilization on surfaces is a proven and popular method. However, many protocols lead to random orientation and the formation of undefined or even inactive by-products. Most concepts to obtain a more targeted conjugation or immobilization requires the recombinant modification of at least one binding partner, which is often impractical or prohibitively expensive. Here a novel method is presented, which is based on the chemical preactivation of Protein A or G with selected conventional crosslinkers. In a second step, the antibody is added, which is subsequently crosslinked in the Fc part. This leads to an oriented and covalent immobilization of the immunoglobulin with a very high yield. Protocols for Protein A and Protein G with murine and human IgG are presented. This method may be useful for the preparation of columns for affinity chromatography, immunoprecipitation, antibodies conjugated to magnetic particles, permanent and oriented immobilization of antibodies in biosensor systems, microarrays, microtitration plates or any other system, where the loss of antibodies needs to be avoided, and maximum binding capacity is desired. This method is directly applicable even to antibodies in crude cell culture supernatants, raw sera or protein-stabilized antibody preparations without any purification nor enrichment of the IgG. This new method delivered much higher signals as a traditional method and, hence, seems to be preferable in many applications. KW - Antibody coating KW - Proximity-enhanced reaction KW - Immunoglobulins KW - IgG KW - Protein G KW - Protein A KW - Immunoprecipitation KW - Immunocapture KW - Stabilization KW - Biosensor KW - Biochip KW - Microarray KW - ELISA KW - Immunoassay KW - Immunosensor KW - Crosslinker KW - Nanoparticles KW - Click chemistry KW - Herceptin KW - Trastuzumab PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-478797 SP - 1 EP - 17 PB - MDPI CY - Basel AN - OPUS4-47879 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -