TY - JOUR A1 - Geißler, Daniel A1 - Wegner, Karl David A1 - Fischer, C. A1 - Resch-Genger, Ute T1 - Exploring Simple Particle-Based Signal Amplification Strategies in a Heterogeneous Sandwich Immunoassay with Optical Detection N2 - Heterogeneous sandwich immunoassays are widely used for biomarker detection in bioanalysis and medical diagnostics. The high analyte sensitivity of the current “gold standard” enzyme-linked immunosorbent assay (ELISA) originates from the signal-generating enzymatic amplification step, yielding a high number of optically detectable reporter molecules. For future point-of-care testing (POCT) and point-of-need applications, there is an increasing interest in more simple detection strategies that circumvent time-consuming and temperature-dependent enzymatic reactions. A common concept to aim for detection limits comparable to those of enzymatic amplification reactions is the usage of polymer nanoparticles (NP) stained with a large number of chromophores. We explored different simple NP-based signal amplification strategies for heterogeneous sandwich immunoassays that rely on an extraction-triggered release step of different types of optically detectable reporters. Therefore, streptavidinfunctionalized polystyrene particles (PSP) are utilized as carriers for (i) the fluorescent dye coumarin 153 (C153) and (ii) hemin (hem) molecules catalyzing the luminol reaction enabling chemiluminescence (CL) detection. Additionally, (iii) NP labeling with hemin-based microperoxidase MP11 was assessed. For each amplification approach, the PSP was first systematically optimized regarding size, loading concentration, and surface chemistry. Then, for an immunoassay for the inflammation marker C- eactive protein (CRP), the analyte sensitivity achievable with optimized PSP ystems was compared with the established ELISA concept for photometric and CL detection. Careful optimization led to a limit of detection (LOD) of 0.1 ng/mL for MP11-labeled PSP and CL detection, performing similarly well to a photometric ELISA (0.13 ng/mL), which demonstrates the huge potential of our novel assay concept. KW - Nanoparticle KW - Fluorescence KW - Immunoassay KW - Quality assurance KW - Antibody KW - Polymer KW - Dye KW - Signal enhancement KW - CRP KW - Biosensing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597853 DO - https://doi.org/10.1021/acs.analchem.3c03691 SN - 1520-6882 VL - 96 IS - 13 SP - 5078 EP - 5085 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-59785 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heckmann, A. A1 - Dümmler, S. A1 - Pauli, Jutta A1 - Margraf, M. A1 - Köhler, J. A1 - Stich, D. A1 - Lambert, C. A1 - Fischer, I. A1 - Resch-Genger, Ute T1 - Highly fluorescent open-shell NIR dyes: the time-dependence of back electron transfer in triarylamine-perchlorotriphenylmethyl radicals KW - Triarylamine-perchlorotriphenylmethyl radical KW - Dono-acceptor compounds KW - CT state KW - Fluorescence quantum KW - Yield KW - Life time PY - 2009 DO - https://doi.org/10.1021/jp908425w SN - 1932-7447 SN - 1089-5639 VL - 113 SP - 20958 EP - 20966 PB - Soc. CY - Washington, DC AN - OPUS4-20757 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard A1 - Weiß, André A1 - Sturm, Heinz A1 - Kleemeier, M. A1 - Hartwig, A. A1 - Vogt, C. A1 - Fischer, R.X. T1 - Layered silicate epoxy nanocomposites: formation of the inorganic-carbonaceous fire protection layer N2 - The layered silicate (LS) modification and processing parameters applied control the morphology of the LS/polymer composites. Here, increasing the surface area of the LS particles by using alternative drying processes increases dispersion towards a more typical nanocomposite morphology, which is a basic requirement for promising flame retardancy. Nevertheless, the morphology at room temperature does not act itself with respect to flame retardancy, but serves as a prerequisite for the formation of an efficient surface protection layer during pyrolysis. The formation of this residue layer was addressed experimentally for the actual pyrolysis region of a burning nanocomposite and thus our results are valid without any assumptions or compromises on the time period, dimension, surrounding atmosphere or temperature. The formation of the inorganic-carbonaceous residue is influenced by bubbling, migration, reorientation, agglomeration, ablation, and perhaps also delamination induced thermally and by decomposition, whereas true sintering of the inorganic particles was ruled out as an important mechanism. Multiple, quite different mechanisms are relevant during the formation of the residue, and the importance of each mechanism probably differs from one nanocomposite system to another. The main fire protection effect of the surface layer in polymer nanocomposites based on non-charring or nearly non-charring polymers is the increase in surface temperature, resulting in a substantial increase in reradiated heat flux (heat shielding). KW - Nanocomposite KW - Fire retardancy KW - Epoxy resin KW - Fire behavior KW - Flammability PY - 2011 DO - https://doi.org/10.1002/pat.1644 SN - 1042-7147 SN - 1099-1581 VL - 22 IS - 12 SP - 1581 EP - 1592 PB - John Wiley & Sons, Ltd. CY - Chichester AN - OPUS4-24916 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Markwart, Jens C. A1 - Battig, Alexander A1 - Zimmermann, Lisa A1 - Wagner, Martin A1 - Fischer, Jochen A1 - Schartel, Bernhard A1 - Wurm, Frederik R. T1 - Systematically controlled decomposition mechanism in phosphorus flame retardants by precise molecular architecture: P−O vs P−N N2 - Flame retardants (FR) are inevitable additives to many plastics. Halogenated organics are effective FRs but are controversially discussed due to the release of toxic gases during a fire or their persistence if landfilled. Phosphorus-containing compounds are effective alternatives to halogenated FRs and have potential lower toxicity and degradability. In addition, nitrogencontaining additives were reported to induce synergistic effects with phosphorus-based FRs. However, no systematic study of the gradual variation on a single phosphorus FR containing both P−O and P−N moieties and their comparison to the respective blends of phosphates and phosphoramides was reported. This study developed general design principles for P−O- and P−N-based FRs and will help to design effective FRs for various polymers. We synthesized a library of phosphorus FRs that only differ in their P-binding pattern from each other and studied their decomposition mechanism in epoxy resins. Systematic control over the decomposition pathways of phosphate (PO(OR)3), phosphoramidate (PO(OR)2(NHR)), phosphorodiamidate (PO(OR)(NHR)2), phosphoramide (PO(NHR)3), and their blends was identified, for example, by reducing cis-elimination and the formation of P−N-rich char with increasing nitrogen content in the P-binding sphere. Our FR epoxy resins can compete with commercial FRs in most cases, but we proved that the blending of esters and amides outperformed the single molecule amidates/diamidates due to distinctively different decomposition mechanisms acting synergistically when blended. KW - Phosphorus KW - Flame retardants KW - Epoxies KW - Mechanistic study KW - Toxicity PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481549 DO - https://doi.org/10.1021/acsapm.9b00129 SN - 2637-6105 VL - 1 IS - 5 SP - 1118 EP - 1128 PB - ACS AN - OPUS4-48154 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Zerstörungsfreie Charakterisierung der Alterung additiv gefertigter Kunststoffbauteile N2 - Das vorgestellte Projekt beschäftigt sich mit den optischen, thermophysikalischen und mechanischen Materialeigenschaften von additiv gefertigten Kunststoffteilen und deren Alterung. Dazu wurden mittels Fused Layer Modeling (FLM) Probekörper aus ABS hergestellt, die anschließend für drei Monate einer künstlichen Bewitterung unterzogen wurden. Die dabei erzeugte definierte Alterung wurde nach drei Zeitabschnitten jeweils mit zerstörungsfreien Methoden charakterisiert. Dabei wurde neben den spektroskopischen Standardmethoden auch die aktive Thermografie eingesetzt. Die Ergebnisse zeigen, dass sich mittels der Thermografie sowohl chemische Veränderungen als auch mechanische Schädigungen (Fehlstellen) darstellen lassen. Die Bewitterung beeinflusst die Teiltransparenz der Proben zumindest im sichtbaren Spektralbereich, was bei der Charakterisierung der Fehlstellen, die mittels optisch angeregter aktiver Thermografie detektiert wurden, berücksichtigt werden muss. T2 - DGZfP-Jahrestagung 2019 CY - Friedrichshafen, Germany DA - 27.05.2019 KW - 3D Druck KW - Additive Fertigung KW - Thermografie KW - Polymere KW - Künstliche Bewitterung PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-491561 UR - https://jt2019.dgzfp.de/Portals/jt2019/bb/Di.3.B.1.pdf SN - 978-3-947971-02-2 VL - 171 SP - 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-49156 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Metz, Christian A1 - Franz, Philipp A1 - Maierhofer, Christiane A1 - Wachtendorf, Volker A1 - Fischer, C. ED - Ziegahn, K.-F. T1 - Untersuchung der Beständigkeit additiv gefertigter Bauteile durch Thermografie nach künstlicher Bewitterung N2 - Additiv gefertigte Prüfkörper aus Polyamid 12 (Laser Sinter Verfahren) und Acrylnitril-Butadien-Styrol (Fused Layer Modeling Verfahren) wurden über 2000 Stunden künstlich bewittert und ihr Alterungsverhalten untersucht. Die Ergebnisse wurden anschließend mit denen von Prüfkörpern verglichen, welche auf dieselbe Weise künstlich bewittert, aber mittels konventionellem KunststoffSpritzguss hergestellt wurden. T2 - 48. Jahrestagung der GUS 2019 CY - Stutensee, Germany DA - 27.03.2019 KW - Polymere KW - Additive Fertigung KW - 3D Druck KW - Künstliche Bewitterung KW - Thermografie PY - 2019 SN - 978-3-9818507-3-4 VL - 48 SP - 207 EP - 216 CY - Pfinztal (Berghausen) AN - OPUS4-48502 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Metz, Christian A1 - Franz, Philipp A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Active thermography for quality assurance of 3D-printed polymer structures N2 - Additively manufactured test specimens made of polyamide 12 (PA 12) by Laser Sintering as well as of acrylonitrile butadiene styrene (ABS) by Fused Layer Modelling, were characterised with active thermography directly after manufacturing and after artificial weathering. For this, two different excitation methods (flash and pulse heating) were used and compared, regarding their suitability for the detection of constructed and imprinted defects inside the test specimens. To increase the quality of the thermograms, data processing methods like thermal signal reconstruction (TSR) and Fourier Transformation after TSR were applied. To further investigate the long-term stability of the additively manufactured test specimens towards environmental stress, like UV radiation, heat, humidity, water contact and frost with active thermography, an artificial weathering test over 2000 hours (~3 months) was applied to the specimens. The monitoring of the changes in the optical properties of the weathered plastics was supplemented by spectral reflectance and UV/VIS spectroscopy. KW - Additive manufacturing KW - Polymers KW - Artificial weathering KW - Active thermography KW - UV/VIS spectroscopy PY - 2019 DO - https://doi.org/10.1080/17686733.2019.1686896 SN - 1768-6733 (Print) 2116-7176 (Online) VL - 18 IS - 1 SP - 50 EP - 72 PB - Taylor & Francis AN - OPUS4-49817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauzon, C. A1 - Mishurova, Tatiana A1 - Fischer, M. A1 - Ahlström, J. A1 - Fritsch, Tobias A1 - Bruno, Giovanni A1 - Hryha, Eduard T1 - Impact of contour scanning and helium-rich process gas on performances of Alloy 718 lattices produced by laser powder bed fusion N2 - Contour scanning and process gas type are process parameters typically considered achieving second order effects compared to first order factors such as laser power and scanning speed. The present work highlights that contour scanning is crucial to ensure geometrical accuracy and thereby the high performance under uniaxial compression of complex Alloy 718 lattice structures. Studies of X-ray computed tomography visualizations of as-built and compression-strained structures reveal the continuous and smooth bending and compression of the walls, and the earlier onset of internal contact appearance in the denser lattices printed with contour. In contrast, the effect of addition of He to the Ar process gas appears to have limited influence on the mechanical response of the lattices and their microstructure as characterized by electron backscattered diffraction. However, the addition of He proved to significantly enhance the cooling rate and to reduce the amount of the generated spatters as evidenced by in situ monitoring of the process emissions, which is very promising for the process stability and powder reusability during laser powder bed fusion. KW - Additive manufacturing KW - Laser powder bed fusion KW - Gyroid lattice KW - Process atmosphere PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546632 DO - https://doi.org/10.1016/j.matdes.2022.110501 SN - 0264-1275 VL - 215 SP - 110501 PB - Elsevier Ltd. AN - OPUS4-54663 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gers-Panther, C.F. A1 - Fischer, H. A1 - Nordmann, J. A1 - Seiler, T. A1 - Behnke, Thomas A1 - Würth, Christian A1 - Frank, W. A1 - Resch-Genger, Ute A1 - Müller, T.J.J. T1 - Four- and Five-Component Syntheses and Photophysical Properties of Emission Solvatochromic 3‑Aminovinylquinoxalines N2 - 3-Aminovinylquinoxalines are readily accessible from (hetero)aryl glyoxylic acids or heterocyclic π-nucleophiles by consecutive four- and fivecomponent syntheses in the sense of an activation-alkynylation-cyclocondensation-addition sequence or glyoxylation-alkynylation-cyclocondensation-addition sequence in good yields. The title compounds are highly fluorescent with pronounced emission solvatochromicity and protochromic fluorescence quenching. Time-resolved fluorescence spectroscopy furnishes radiative and nonradiative fluorescence decay rates in various solvent polarities. The electronic structure is corroborated by DFT and TD-DFT calculations rationalizing the observed spectroscopic effects. KW - Dye KW - Syntheseis KW - Spectroscopy PY - 2016 DO - https://doi.org/10.1021/acs.joc.6b02581 SN - 0022-3263 VL - 82 SP - 567 EP - 578 PB - ACS Publications AN - OPUS4-39211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fischer, J.L. A1 - Lutomski, C.A. A1 - El-Baba, T.J. A1 - Siriwardena-Mahanama, B.N. A1 - Weidner, Steffen A1 - Falkenhagen, Jana A1 - Allen, M. J. A1 - Trimpin, S. T1 - Matrix-assisted ionization-ion mobility spectrometry-mass spectrometry: Selective analysis of a europium-PEG complex in a crude mixture N2 - The analytical utility of a new and simple to use ionization method, matrix-assisted ionization (MAI), coupled with ion mobility spectrometry (IMS) and mass spectrometry (MS) is used to characterize a 2-armed europium(III)-containing poly(ethylene glycol) (Eu-PEG) complex directly from a crude sample. MAI was used with the matrix 1,2-dicyanobenzene, which affords low chemical background relative to matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI). MAI provides high ion abundance of desired products in comparison to ESI and MALDI. Inductively coupled plasma-MS measurements were used to estimate a maximum of 10% of the crude sample by mass was the 2-arm Eu-PEG complex, supporting evidence of selective ionization of Eu-PEG complexes using the new MAI matrix, 1,2-dicyanobenzene. Multiply charged ions formed in MAI enhance the IMS gas-phase separation, especially relative to the singly charged ions observed with MALDI. Individual components are cleanly separated and readily identified, allowing characterization of the 2-arm Eu-PEG conjugate from a mixture of the 1-arm Eu-PEG complex and unreacted starting materials. Size-exclusion chromatography, liquid chromatography at critical conditions, MALDI-MS, ESI-MS, and ESI-IMS-MS had difficulties with this analysis, or failed. KW - Matrix-assisted ionization ion mobility spectrometry mass spectrometry KW - Europium KW - Poly(ethylene glycol) KW - Size-exclusion chromatography KW - Liquid chromatography at critical conditions KW - Electrospray ionization KW - Matrix-assisted laser desorption/ionization KW - Inductively coupled plasma-mass spectrometry KW - ESI KW - MALDI KW - SEC PY - 2015 DO - https://doi.org/10.1007/s13361-015-1233-8 SN - 1044-0305 VL - 26 IS - 12 SP - 2086 EP - 2095 PB - Elsevier CY - New York, NY AN - OPUS4-35283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -