TY - JOUR A1 - Rades, Steffi A1 - Hodoroaba, Vasile-Dan A1 - Salge, T. A1 - Wirth, Thomas A1 - Lobera, M.P. A1 - Labrador, R.H. A1 - Natte, Kishore A1 - Behnke, Thomas A1 - Gross, Thomas A1 - Unger, Wolfgang T1 - High-resolution imaging with SEM/T-SEM, EDX and SAM as a combined methodical approach for morphological and elemental analyses of single engineered nanoparticles N2 - The combination of complementary characterization techniques such as SEM (Scanning Electron Microscopy), T-SEM (Scanning Electron Microscopy in Transmission Mode), EDX (Energy Dispersive X-ray Spectroscopy) and SAM (Scanning Auger Microscopy) has been proven to be a powerful and relatively quick characterization strategy for comprehensive morphological and chemical characterization of individual silica and titania nanoparticles. The selected “real life” test materials, silica and titania, are listed in the OECD guidance manual as representative examples because they are often used as commercial nanomaterials. Imaging by high resolution SEM and in the transmission mode by T-SEM allows almost simultaneous surface and in-depth inspection of the same particle using the same instrument. EDX and SAM enable the chemical characterization of bulk and surface of individual nanoparticles. The core–shell properties of silica based materials are addressed as well. Titania nominally coated by silane purchased from an industrial source has been found to be inhomogeneous in terms of chemical composition. KW - surface and in-depth inspection KW - silica nanoparticles KW - titania nanoparticles PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-316296 DO - https://doi.org/10.1039/c4ra05092d SN - 2046-2069 VL - 4 IS - 91 SP - 49577 EP - 49587 PB - RSC Publishing CY - London AN - OPUS4-31629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Moser, Marko A1 - Schneider, Ralf A1 - Behnke, Thomas A1 - Schneider, Thomas A1 - Falkenhagen, Jana A1 - Resch-Genger, Ute T1 - Ellman’s and aldrithiol assay as versatile and complementary tools for the quantification of thiol groups and ligands on nanomaterials N2 - Simple, fast, and versatile methods for the quantification of thiol groups are of considerable interest not only for protein analysis but also for the characterization of the surface chemistry of nanomaterials stabilized with thiol ligands or bearing thiol groups for the subsequent (bio-) functionalization via maleimide−thiol chemistry. Here, we compare two simple colorimetric assays, the widely used Ellman’s assay performed at alkaline pH and the aldrithiol assay executed at acidic and neutral pH, with respect to their potential for the quantification of thiol groups and thiol ligands on different types of nanoparticles like polystyrene nanoparticles, semiconductor nanocrystals (SC NC), and noble metal particles, and we derive criteria for their use. In order to assess the underlying reaction mechanisms and to obtain stoichiometry factors mandatory for reliable thiol quantification, both methods were studied photometrically and with electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), thereby demonstrating the influence of different thiols on the reaction mechanism. Our results underline the suitability of both methods for the quantification of directly accessible thiol groups or ligands on the surface of 2D- and 3D-supports, here exemplarily polystyrene nanoparticles. Moreover, we could derive strategies for the use of these simple assays for the determination of masked (i.e., not directly accessible) thiol groups like disulfides such as lipoic acid and thiol stabilizing ligands coordinatively bound to Cd and/or Hg surface atoms of II/VI and ternary SC NC and to gold and silver nanoparticles. KW - Nanoparticles KW - Ligands KW - Ellman KW - Aldrithiol KW - Quantification PY - 2016 DO - https://doi.org/10.1021/acs.analchem.6b01798 SN - 0003-2700 SN - 1520-6882 VL - 88 IS - 17 SP - 8624 EP - 8631 PB - ACS Publications CY - Washington AN - OPUS4-37561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nirmalananthan-Budau, Nithiya A1 - Behnke, Thomas A1 - Hoffmann, Katrin A1 - Kage, Daniel A1 - Gers-Panther, Charlotte F. A1 - Frank, Walter A1 - Müller, Thomas J. J. A1 - Resch-Genger, Ute T1 - Crystallization and Aggregation-Induced Emission in a Series of Pyrrolidinylvinylquinoxaline Derivatives N2 - Aggregation-induced emission (AIE) has been meanwhile observed for many dye classes and particularly for fluorophores containing propeller-like groups. Herein, we report on the AIE characteristics of a series of four hydrophobic pyrrolidinylvinylquinoxaline (PVQ) derivatives with phenyl, pyrrolyl, indolyl, and methoxythienyl substituents used to systematically vary the torsion angle between this substituent at the quinoxaline C2 position and the planar PVQ moiety. These molecules, which are accessible via four- or five-component one-pot syntheses, were spectroscopically studied in organic solvents and solvent−water mixtures, as dye aggregates, solids, and entrapped in polystyrene particles (PSP). Steady-state and time-resolved fluorescence measurements revealed a strong fluorescence enhancement for all dyes in ethanol−water mixtures of high water content, accompanying the formation of dye aggregates with sizes of a few hundred nm, overcoming polarity and H-bonding-induced fluorescence quenching of the chargetransfer-type emission of these PVQ dyes. The size and shape of these dye aggregates and the size of the AIE effect are controlled by the water content and the substituent-dependent torsion angle that influences the nucleation process and the packing of the molecules during aggregation. Staining of 1 μm-sized carboxy-functionalized PSP with the PVQ dyes resulted also in a considerable increase in the fluorescence quantum yield and lifetime, reflecting the combined influence of the restricted molecular motion and the reduced polarity of the dye microenvironment. KW - Spectroscopy KW - AIE KW - Aggregates KW - Nanoparticle PY - 2018 DO - https://doi.org/10.1021/acs.jpcc.8b01425 SN - 1932-7447 N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. VL - 122 IS - 20 SP - 11119 EP - 11127 PB - ACS Publications AN - OPUS4-45176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Behnke, Thomas A1 - Moser, Marko A1 - Behnke, Thomas A1 - Hoffmann, Katrin A1 - Höhne, Robert A1 - Resch-Genger, Ute T1 - Design and Characterization of NIR-emissive PEGylated and Protein-functionalized Nanoparticles for Bioanalytics T2 - 7th Senftenberger Innovationsforum Multiarameteranalytik CY - Senftenberg, Germany DA - 2013-04-18 PY - 2013 AN - OPUS4-28466 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Behnke, Thomas A1 - Mathejczyk, J. A1 - Napp, J. A1 - Hoffmann, Katrin A1 - Würth, Christian A1 - Alves, F. A1 - Schäferling, M. A1 - Resch-Genger, Ute T1 - Targeted NIR-emissive nanosensors for bioimaging T2 - 7th Senftenberger Innovationsforum Multiparameteranalytik CY - Senftenberg, Germany DA - 2013-04-18 PY - 2013 AN - OPUS4-28468 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Behnke, Thomas A1 - Mathejczyk, J. A1 - Würth, Christian A1 - Napp, J. A1 - Hoffmann, Katrin A1 - Alves, F. A1 - Schäferling, M. A1 - Resch-Genger, Ute A1 - Lehmann, Andreas T1 - Design and Bioanalytical Applications of NIR-Fluorescent Polystyrene Nanoparticles T2 - Imaging Innovations of the Lung CY - Göttingen, Germany DA - 2012-04-18 PY - 2012 AN - OPUS4-25698 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Behnke, Thomas A1 - Würth, Christian A1 - Napp, J. A1 - Fischer, L. A1 - Alves, F. A1 - Schäferling, M. A1 - Resch-Genger, Ute T1 - Targeted ratiometric Nanosensors for the in Vivo Imaging of Tumor Hypoxia in the NIR spectral region T2 - Tag der Chemie CY - Regensburg, Germany DA - 2012-06-28 PY - 2012 AN - OPUS4-26020 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Behnke, Thomas A1 - Würth, Christian A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute T1 - Rational Design and Absolute Quantum yields of NIR-Fluorescent Nanoparticls for Bioanalytical Applications T2 - Innovationsforum "Funktionelle Farbstoffe" CY - Bitterfeld-Wolfen, Germany DA - 2012-05-31 PY - 2012 AN - OPUS4-26021 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Behnke, Thomas A1 - Würth, Christian A1 - Mathejczyk, J. A1 - Napp, J. A1 - Hoffmann, Katrin A1 - Alves, F. A1 - Schäferling, M. A1 - Resch-Genger, Ute T1 - NIR-Fluorescent Polystyrene Nanoparticles: Design, Optical Characterization and Bioanalytical Applications T2 - Abteilungsseminar BfR CY - Berlin, Germany DA - 2012-06-15 PY - 2012 AN - OPUS4-26022 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauli, Jutta A1 - Brehm, Robert A1 - Grabolle, Markus A1 - Behnke, Thomas A1 - Mathejczyk, J. A1 - Hamann, F. A1 - Alves, F. A1 - Hilger, I. A1 - Resch-Genger, Ute ED - Achilefu, S. ED - Raghavachari, R. T1 - Dye-biomolecule conjugates and NIR-fluorescent particles for targeting of disease-related biomarkers N2 - Indispensable for fluorescence imaging are highly specific and sensitive molecular probes that absorb and emit in the near infrared (NIR) spectral region and respond to or target molecular species or processes. Here, we present approaches to targeted fluorescent probes for in vivo imaging in the intensity and lifetime domain exploiting NIR dyes. Screening schemes for the fast identification of suitable fluorophores are derived and design criteria for highly emissive optical probes. In addition, as a signal amplification strategy that enables also the use of hydrophobic NIR fluorophores as fluorescent reporters, first steps towards versatile strategies for the preparation of NIR-fluorescent polymeric particles are presented that can be utilized also for the design of targeted and analyte-responsive probes. KW - Fluorescence KW - Fluorescence lifetime imaging KW - Near-infrared KW - NIR KW - Cyanine dye KW - Cancer KW - In vivo imaging KW - Aggregation KW - Nanoparticle PY - 2011 DO - https://doi.org/10.1117/12.876828 SN - 1605-7422 N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE IS - 7910 SP - 791014-1 EP - 791014-15 AN - OPUS4-24353 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -