TY - JOUR A1 - Weller, Michael G. T1 - Quality issues of research antibodies N2 - According to several recent studies, an unexpectedly high number of landmark papers seem to be not reproducible by Independent laboratories. Nontherapeutic antibodies used for research, diagnostic, food analytical, environmental, and other purposes play a significant role in this matter. Although some papers have been published offering suggestions to improve the situation, they do not seem to be comprehensive enough to cover the full complexity of this issue. In addition, no obvious improvements could be noticed in the field as yet. This article tries to consolidate the remarkable variety of conclusions and suggested activities into a more coherent conception. It is concluded that funding agencies and journal publishers need to take first and immediate measures to resolve these problems and lead the way to a more sustainable way of bioanalytical research, on which all can rely with confidence. KW - reproducibility crisis KW - irreproducibility KW - replication KW - paper retraction KW - peer reviewimmunochemistry KW - immunoassay KW - ligand binding assay KW - monoclonal antibody KW - quality control KW - cross-reactivity KW - non-specific binding KW - selectivity PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-356254 DO - https://doi.org/10.4137/ACI.S31614 SN - 1177-3901 VL - 11 SP - 21 EP - 27 PB - Libertas Academica CY - Auckland, New Zealand AN - OPUS4-35625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Filimonova, S. M. A1 - Melnikov, E. S. A1 - Kaufmann, Jan Ole A1 - Shchepochkina, O. Y. A1 - Eremin, S. A. A1 - Gravel, I. V. A1 - Raysyan, Anna T1 - Exploring the anti‐α‐amylase activity of flavonoid aglycones in fabaceae plant extracts: a combined MALDI‐TOF‐MS and LC–MS/MS approach N2 - A combination of TLC-bioautography, MALDI-TOF-MS and LC–MS/MS methods was used to identify flavonoids with anti-α-amylase activity in extracts of Lathyrus pratensis L. (herb), L. polyphillus L. (fruits), Thermopsis lanceolata R. Br. (herb) and S. japonica L. (buds). After the TLC-autobiography assay, substances with anti-amylase activity were identified by MALDI-TOF-MS followed by confirmation of the result by LC–MS/MS. Results of the study revealed that the flavonoids apigenin, luteolin, formononetin, genistein and kaempferol display marked anti-α-amylase activity. Formononetin showed the largest activity. Compared with LC–MS/MS, MALDI-TOF-MS is a quick and convenient method; results can be obtained within minutes; and only minor sample amounts are required which allows us to analyse mixtures of substances without preliminary separation. However, the inability to distinguish between isomers is the main limitation of the method. KW - Enzyme KW - MALDI-TOF-MS KW - LC-MS/MS KW - Massenspektrometrie PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-577128 DO - https://doi.org/https://doi.org/10.1111/ijfs.16491 SN - 0950-5423 VL - 58 IS - 7 SP - 3902 EP - 3911 PB - Wiley & Sons CY - Hoboken, NJ, USA AN - OPUS4-57712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weller, Michael G. T1 - The mystery of homochirality on earth N2 - Homochirality is an obvious feature of life on Earth. On the other hand, extraterrestrial samples contain largely racemic compounds. The same is true for any common organic synthesis. Therefore, it has been a perplexing puzzle for decades how these racemates could have formed enantiomerically enriched fractions as a basis for the origin of homochiral life forms. Numerous hypotheses have been put forward as to how preferentially homochiral molecules could have formed and accumulated on Earth. In this article, it is shown that homochirality of the abiotic organic pool at the time of formation of the first self-replicating molecules is not necessary and not even probable. It is proposed to abandon the notion of a molecular ensemble and to focus on the level of individual molecules. Although the formation of the first self-replicating, most likely homochiral molecule, is a seemingly improbable event, on a closer look, it is almost inevitable that some homochiral molecules have formed simply on a statistical basis. In this case, the non-selective leap to homochirality would be one of the first steps in chemical evolution directly out of a racemic “ocean”. Moreover, most studies focus on the chirality of the primordial monomers with respect to an asymmetric carbon atom. However, any polymer with a minimal size that allows folding to a secondary structure would spontaneously lead to asymmetric higher structures (conformations). Most of the functions of these polymers would be influenced by this inherently asymmetric folding. Furthermore, a concept of physical compartmentalization based on rock nanopores in analogy to nanocavities of digital immunoassays is introduced to suggest that complex cell walls or membranes were also not required for the first steps of chemical evolution. To summarize, simple and universal mechanisms may have led to homochiral self-replicating systems in the context of chemical evolution. A homochiral monomer pool is deemed unnecessary and probably never existed on primordial Earth. N2 - Homochiralität ist ein offensichtliches Merkmal des Lebens auf der Erde. Andererseits enthalten extraterrestrische Proben überwiegend racemische Verbindungen. Dasselbe gilt für jede gängige organische Synthese. Daher war es jahrzehntelang ein Rätsel, wie diese Racemate enantiomeren-angereicherte Fraktionen als Grundlage für den Ursprung homochiraler Lebensformen bilden konnten. Zahlreiche Hypothesen wurden aufgestellt, wie sich bevorzugt homochirale Moleküle auf der Erde gebildet und angereichert haben könnten. In diesem Artikel wird gezeigt, dass Homochiralität des abiotischen organischen Pools zum Zeitpunkt der Bildung der ersten selbstreplizierenden Moleküle nicht notwendig und nicht einmal wahrscheinlich ist. Es wird vorgeschlagen, die Vorstellung eines molekularen Ensembles aufzugeben und sich auf die Ebene der einzelnen Moleküle zu konzentrieren. Obwohl die Bildung des ersten selbstreplizierenden, höchstwahrscheinlich homochiralen Moleküls ein scheinbar unwahrscheinliches Ereignis ist, ist es bei näherer Betrachtung fast unvermeidlich, dass sich einige homochirale Moleküle einfach auf statistischer Basis gebildet haben. In diesem Fall wäre der nichtselektive Sprung zur Homochiralität einer der ersten Schritte der chemischen Evolution direkt aus einem racemischen "Ozean". Darüber hinaus konzentrieren sich die meisten Studien auf die Chiralität der ursprünglichen Monomere in Bezug auf ein asymmetrisches Kohlenstoffatom. Jedes Polymer mit einer Mindestgröße, die eine Faltung zu einer Sekundärstruktur erlaubt, würde jedoch spontan zu asymmetrischen höheren Strukturen (Konformationen) führen. Die meisten Funktionen dieser Polymere würden durch diese inhärent asymmetrische Faltung beeinflusst. Darüber hinaus wird ein Konzept der physikalischen Kompartimentierung auf der Basis von Gesteinsnanoporen in Analogie zu den Nanokavitäten digitaler Immunoassays vorgestellt, das darauf hindeutet, dass auch für die ersten Schritte der chemischen Evolution keine komplexen Zellwände oder Membranen notwendig waren. Zusammenfassend lässt sich sagen, dass einfache und universelle Mechanismen zu homochiralen selbstreplizierenden Systemen im Rahmen der chemischen Evolution geführt haben könnten. Ein homochiraler Monomerpool wird als unnötig angesehen, welcher auf der Urerde wahrscheinlich nie existiert hat. KW - Chemical evolution KW - Enantiomeric excess ee KW - Chirality KW - Racemate KW - Folding chirality KW - Self-assembly KW - self-replication KW - Single molecule KW - Prebiotic chemistry KW - Protein folding KW - Peptide folding KW - Proteinoid KW - Conformation KW - Segregation KW - Compartmentalization KW - Digital immunoassay KW - Porous rock KW - Miller and Urey KW - Primordial soup KW - Murchison meteorite KW - Micrometeorites KW - Tholins PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598349 DO - https://doi.org/10.3390/life14030341 SN - 2075-1729 VL - 14 IS - 3 SP - 1 EP - 13 PB - MDPI CY - Basel AN - OPUS4-59834 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raab, A. R. A1 - Grießler, T. R. A1 - Rück, D. A1 - Li, Z. A1 - Zens, A. A1 - Bruckner, J. R. A1 - Huber, P. A1 - Schönhals, Andreas A1 - Szymoniak, Paulina A1 - Laschat, S. T1 - Salt complexation drives liquid crystalline selfassembly in crown ether–amino acid hybrids N2 - Crown ether–amino acid hybrids represent a promising class of amphiphilic molecules combining ion recognition with self-assembly capabilities. Despite extensive studies on their binding properties, the influence of inorganic salt complexation on their liquid crystalline behaviour remains underexplored. Here we synthesized amphiphilic [18]-crown-6 derivatives of L-dihydroxyphenylalanine and tetrahydroisoquinoline analogues, systematically investigating the effects of alkyl chain length and salt type on mesophase formation. Complexation with various salts induced liquid crystalline phases, transitioning from smectic A to columnar hexagonal structures as anion size and alkyl chain length increased. Structural analyses and electron density mapping revealed assembly into charged superdiscs forming columnar stacks with tunable ion channels. Broadband dielectric spectroscopy highlighted differences in molecular mobility and conductivity linked to molecular design. These findings establish salt complexation as a key strategy to control self-assembly and ion transport in crown ether–amino acid hybrids, advancing their potential in responsive soft materials and ion-conductive applications. KW - Ionic liquid crystals PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655986 DO - https://doi.org/10.1039/d5tc04129e SP - 1 EP - 18 PB - Royal Society of Chemistry (RSC) AN - OPUS4-65598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frechilla, A. A1 - Martínez, E. A1 - del Moral, J. A1 - López-Santos, C. A1 - Frechilla, J. A1 - Nuñez-Gálvez, F. A1 - López-Flores, V. A1 - de la Fuente, G.F. A1 - Hülagü, Deniz A1 - Bonse, Jörn A1 - González-Elipe, A.R. A1 - Borrás, A. A1 - Angurel, L.A. T1 - Influence of near-edge Laser-Induced Periodic Surface Structures (LIPSS) on the electrical properties of fs-laser-machined ITO microcircuits N2 - Scalable, cost-effective methods for processing transparent electrodes at the microscale are pivotal to advancing in electrochemistry, optoelectronics, microfluidics, and energy harvesting. In these fields, the precise fabrication of micrometric circuits and patterns plays a critical role in determining device performance, material compatibility, and integration with added-value substrates. In this context, Laser Subtractive Manufacturing stands out as a suitable microfabrication technique for its adaptability to diverse materials and complex configurations, as well as its straightforward scalability, affordability, and eco-friendly nature. However, a challenge in micromachining metals and metal oxides is the inherent formation of Laser-Induced Periodic Surface Structures (LIPSS), which can significantly impair electrical conductivity, particularly when circuit dimensions fall within the micrometer range. Herein, we investigate the micromachining of electrical microcircuits using ultrashort pulse laser systems applied to transparent indium tin oxide (ITO) thin films. We analyze the formation of LIPSS at the edges of the micromachined regions associated with the Gaussian distribution of the energy within the laser spot, and the impact of these structures on the electrical properties of the circuits. Thus, we systematically evaluate the influence of LIPSS orientation and periodicity by fabricating various circuit patterns using femtosecond lasers at green (515 nm) and ultraviolet (UV) (343 nm) wavelengths. A correlation between electrical resistivity measurements and microstructure analysis, as determined by field emission scanning electron and transmission electron microscopy, reveals distinct effects of the formed nanostructures depending on the laser source and its polarization. For the green wavelength, the edge side regions where LIPSS are oriented perpendicular to the ITO track exhibit a resistance higher by a factor just above two compared to those where LIPSS are parallel. Additionally, UV laser processing results in a pronounced reduction of ITO thickness at the boundary between the LIPSS region and the substrate. The mechanisms for the formation of LIPSS with both wavelengths are also discussed. Furthermore, we have determined that in narrow conductive tracks with a width ranging from 6 to 8 µm, the impact of LIPSS is particularly significant because the LIPSS structured region occupies a dominant fraction of the total width. KW - ITO KW - Laser-induced periodic surface structures (LIPSS) KW - Laser subtractive manufacturing KW - fs-laser processing KW - Electrical properties PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655921 DO - https://doi.org/10.1016/j.apsusc.2026.166415 SN - 0169-4332 VL - 731 SP - 1 EP - 13 PB - Elsevier B.V. AN - OPUS4-65592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinmuth-Selzle, K. A1 - Tchipilov, Teodor A1 - Backes, A. T. A1 - Tscheuschner, Georg A1 - Tang, K. A1 - Ziegler, K. A1 - Lucas, K. A1 - Pöschl, U. A1 - Fröhlich-Nowoisky, J. A1 - Weller, Michael G. T1 - Determination of the protein content of complex samples by aromatic amino acid analysis, liquid chromatography-UV absorbance, and colorimetry N2 - Fast and accurate determination of the protein content of a sample is an important and non-trivial task of many biochemical, biomedical, food chemical, pharmaceutical, and environmental research activities. Different methods of total protein determination are used for a wide range of proteins with highly variable properties in complex matrices. These methods usually work reasonably well for proteins under controlled conditions, but the results for non-standard and complex samples are often questionable. Here, we compare new and well-established methods, including traditional amino acid analysis (AAA), aromatic amino acid analysis (AAAA) based on the amino acids phenylalanine and tyrosine, reversed-phase liquid chromatography of intact proteins with UV absorbance measurements at 220 and 280 nm (LC-220, LC-280), and colorimetric assays like Coomassie Blue G-250 dye-binding assay (Bradford) and bicinchoninic acid (BCA) assay. We investigated different samples, including proteins with challenging properties, chemical modifications, mixtures, and complex matrices like air particulate matter and pollen extracts. All methods yielded accurate and precise results for the protein and matrix used for calibration. AAA, AAAA with fluorescence detection, and the LC-220 method yielded robust results even under more challenging conditions (variable analytes and matrices). These methods turned out to be well-suited for reliable determination of the protein content in a wide range of samples, such as air particulate matter and pollen. KW - Air particulate matter KW - Aromatic amino acid analysis KW - Atmospheric aerosol KW - Chemical protein modification KW - Derivatization KW - Nitration KW - Nitrotyrosine KW - LC-UV absorbance KW - Pollen extract KW - Protein quantification KW - Protein test KW - Kjeldahl KW - Tyrosine KW - Phenylalanine KW - Hydrolysis KW - Bradford KW - BCA test KW - 280 nm KW - Air filter samples KW - Fluorescence KW - HPLC KW - Chromatography KW - Protein content KW - 150th anniversary of BAM KW - Topical collection: Analytical Methods and Applications in the Materials and Life Sciences PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545924 UR - https://pubmed.ncbi.nlm.nih.gov/35320366/ DO - https://doi.org/10.1007/s00216-022-03910-1 SP - 1 EP - 14 PB - Springer Nature Limited CY - New York, Heidelberg AN - OPUS4-54592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Keller, S. A1 - Borde, T. A1 - Brangsch, J. A1 - Reimann, C. A1 - Kader, A. A1 - Schulze, D. A1 - Buchholz, R. A1 - Kaufmann, Jan Ole A1 - Karst, U. A1 - Schellenberger, E. A1 - Hamm, B. A1 - Makowski, M. R. T1 - Assessment of the hepatic tumor extracellular matrix using elastin‑specific molecular magnetic resonance imaging in an experimental rabbit cancer model N2 - To investigate the imaging performance of an elastin-specific molecular magnetic resonance imaging (MRI) probe with respect to the extracellular matrix (ECM) in an experimental hepatic cancer model. Twelve rabbits with hepatic VX2 tumors were examined using 3 T MRI 14, 21, and 28 days after tumor implantation for two subsequent days (gadobutrol, day 1; elastin-specific probe, day 2). The relative enhancement (RE) of segmented tumor regions (central and margin) and the peritumoral matrix was calculated using pre-contrast and delayed-phase T1w sequences. MRI measurements were correlated to histopathology and element-specific and spatially resolved mass spectrometry (MS). Mixed-model analysis was performed to assess the performance of the elastin-specific probe. In comparison to gadobutrol, the elastin probe showed significantly stronger RE, which was pronounced in the tumor margin (day 14–28: P ≤ 0.007). In addition, the elastin probe was superior in discriminating between tumor regions (χ2(4) = 65.87; P < 0.001). MRI-based measurements of the elastin probe significantly correlated with the ex vivo elastinstain (R = .84; P <0 .001) and absolute gadolinium concentrations (ICP-MS: R = .73, P <0 .01). LA-ICP-MS imaging confirmed the colocalization of the elastin-specific probe with elastic fibers. Elastin-specific molecular MRI is superior to non-specific gadolinium-based contrast agents in imaging the ECM of hepatic tumors and the peritumoral tissue. KW - Elastin-specific molecular agent KW - Extracellular matrix KW - Hepatocellular carcinoma KW - Inductively coupled plasma mass spectroscopy KW - Laser ablation-inductively coupled plasma-mass spectrometry KW - Magnetic resonance imaging KW - MR imaging KW - ESMA KW - Gadolinium PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517360 DO - https://doi.org/10.1038/s41598-020-77624-8 VL - 10 IS - 1 SP - 20785 PB - Nature AN - OPUS4-51736 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lucassen, F. A1 - Pritzkow, Wolfgang A1 - Rosner, M. A1 - Sepulveda, F. A1 - Vasquez, P. A1 - Wilke, H. A1 - Kasemann, S. A. T1 - The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile – Marine sources and diagenetic effects N2 - Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very heavy values generate a compositionally unique material. These compositions trace the presence of guano in natural ecosystems and its use as fertilizer in present and past agriculture. KW - Isotope ratio KW - VPDB KW - Fishmeal KW - Elemental analyser KW - Vario EL III KW - Casein standard KW - ICP-OES KW - Accelerator mass spectrometry PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-407911 DO - https://doi.org/10.1371/journal.pone.0179440 SN - 1932-6203 VL - 12 IS - 6 SP - Article e0179440, 1 EP - 25 PB - PLOS CY - San Francisco, California, US AN - OPUS4-40791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liu, F. A1 - Lakey, P. S. J. A1 - Berkemeier, T. A1 - Tong, H. A1 - Kunert, A. T. A1 - Meusel, H. A1 - Cheng, Y. A1 - Su, H. A1 - Fröhlich-Nowoisky, J. A1 - Lai, S. A1 - Weller, Michael G. A1 - Shiraiwa, M. A1 - Pöschl, U. A1 - Kampf, C. J. T1 - Atmospheric protein chemistry influenced by anthropogenic air pollutants: nitration and oligomerization upon exposure to ozone and nitrogen dioxide N2 - The allergenic potential of airborne proteins may be enhanced via post-translational modification induced by air pollutants like ozone (O3) and nitrogen dioxide (NO2). The molecular mechanisms and kinetics of the chemical modifications that enhance the allergenicity of proteins, however, are still not fully understood. Here, protein tyrosine nitration and oligomerization upon simultaneous exposure of O3 and NO2 were studied in coated-wall flow-tube and bulk solution experiments under varying atmospherically relevant conditions (5–200 ppb O3, 5–200 ppb NO2, 45–96% RH), using bovine serum albumin as a model protein. Generally, more tyrosine residues were found to react via the nitration pathway than via the oligomerization pathway. Depending on reaction conditions, oligomer mass fractions and nitration degrees were in the ranges of 2.5–25% and 0.5–7%, respectively. The experimental results were well reproduced by the kinetic multilayer model of aerosol surface and bulk chemistry (KM-SUB). The extent of nitration and oligomerization strongly depends on relative humidity (RH) due to moisture-induced phase transition of proteins, highlighting the importance of cloud processing conditions for accelerated protein chemistry. Dimeric and nitrated species were major products in the liquid phase, while protein oligomerization was observed to a greater extent for the solid and semi-solid phase states of proteins. Our results show that the rate of both processes was sensitive towards ambient ozone concentration but rather insensitive towards different NO2 levels. An increase of tropospheric ozone concentrations in the Anthropocene may thus promote pro-allergic protein modifications and contribute to the observed increase of allergies over the past decades. KW - Oxidation KW - Nitration KW - Cross-linking KW - Ozone KW - Nitrogen dioxide KW - Dimer KW - Air pollution KW - Diesel KW - Aeroallergens KW - Pollen KW - Tyrosine KW - Nitrotyrosine KW - BSA KW - Albumin PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-418482 DO - https://doi.org/10.1039/c7fd00005g SN - 1359-6640 VL - 200 SP - 413 EP - 427 PB - Royal Society of Chemistry CY - London AN - OPUS4-41848 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 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-393333 UR - https://f1000research.com/articles/6-161/v1#referee-response-20349 DO - https://doi.org/10.5256/f1000research.11700.r20349 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 -