TY - JOUR A1 - Huber, Alexandra A1 - Behnke, Thomas A1 - Würth, Christian A1 - Jäger, Christian A1 - Resch-Genger, Ute T1 - Spectroscopic characterization of coumarin-stained beads: quantification of the number of fluorophores per particle with solid-state 19F-NMR and measurement of absolute fluorescence quantum yields N2 - The rational design of nano- and micrometer-sized particles with tailor-made optical properties for biological, diagnostic, and photonic applications requires tools to characterize the signal-relevant properties of these typically scattering bead suspensions. This includes methods for the preferably nondestructive quantification of the number of fluorophores per particle and the measurement of absolute fluorescence quantum yields and absorption coefficients of suspensions of fluorescent beads for material performance optimization and comparison. Here, as a first proof-of-concept, we present the first time determination of the number of dye molecules per bead using nondestructive quantitative (19F) NMR spectroscopy and 1000 nm-sized carboxylated polystyrene particles loaded with varying concentrations of the laser dye coumarin 153 containing a CF3 group. Additionally, the signal-relevant optical properties of these dye-loaded particles were determined in aqueous suspension in comparison to the free dye in solvents of different polarity with a custom-built integrating sphere setup that enables spectrally resolved measurements of emission, transmission, and reflectance as well absolute fluorescence quantum yields. These measurements present an important step toward absolute brightness values and quantitative fluorescence analysis with particle systems that can be exploited, for example, for optical imaging techniques and different fluorescence assays as well as for the metrological traceability of fluorescence methods. PY - 2012 DO - https://doi.org/10.1021/ac3000682 SN - 0003-2700 SN - 1520-6882 VL - 84 IS - 8 SP - 3654 EP - 3661 PB - American Chemical Society CY - Washington, DC AN - OPUS4-25873 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huber, Alexandra A1 - Jäger, Christian A1 - Hanelt, Sven A1 - Meyer-Plath, Asmus T1 - Festkörper-NMR-Untersuchungen an mehrwandigen Kohlenstoffanoröhren T2 - Festkörper-NMR-Methoden und Anwendungen in der Materialforschung, Seminar der Universität Tübingen CY - Bad Hindelang, Germany DA - 2010-07-18 PY - 2010 AN - OPUS4-21681 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huber, Alexandra A1 - Hanelt, Sven A1 - Meyer-Plath, Asmus A1 - Jäger, Christian T1 - Solid State NMR study of multiwalled carbon nanotubes T2 - GDCh Fachgruppentagung "Magnetische Resonanzspektroskopie" CY - Münster, Germany DA - 2010-09-20 PY - 2010 AN - OPUS4-21682 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huber, Alexandra A1 - Illgen, René A1 - Hanelt, Sven A1 - Jäger, Christian A1 - Unger, Wolfgang A1 - Meyer-Plath, Asmus T1 - Physico-chemical characterization of CNT by XPS and NMR T2 - Inno. CNT Jahrestagung CY - Ettlingen, Germany DA - 2011-01-25 PY - 2011 AN - OPUS4-23094 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huber, Alexandra A1 - Jäger, Christian A1 - Meyer-Plath, Asmus T1 - Solid State NMR study of multiwalled carbon nanotubes T2 - GDCh Tagung Magnetische Resonanz 2009 CY - Dresden, Germany DA - 2009-09-21 PY - 2009 AN - OPUS4-19996 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huber, Alexandra A1 - Behnke, Thomas A1 - Resch-Genger, Ute A1 - Würth, Christian A1 - Jäger, Christian T1 - Quantitative solid-state NMR, absolute fluorescence, and absorption measurements of fluorescent nano- and microparticles T2 - Alpine Conference on solid-State NMR CY - Chamonix, France DA - 2011-09-11 PY - 2011 AN - OPUS4-23733 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niehoff, A. A1 - Mantion, Alexandre A1 - McAloney, R. A1 - Huber, Alexandra A1 - Falkenhagen, Jana A1 - Goh, C.M. A1 - Thünemann, Andreas A1 - Winnik, M. A. A1 - Menzel, H. T1 - Elucidation of the structure of poly(gamma-benzyl-L-glutamate) nanofibers and gel networks in a helicogenic solvent N2 - The synthesis, characterization, self-assembly, and gel formation of poly(γ-benzyl-L-glutamate) (PBLG) in a molecular weight range from ca. 7,000–100,000 g/mol and with narrow molecular weight distribution are described. The PBLG is synthesized by the nickel-mediated ring-opening polymerization and is characterized by size-exclusion chromatography coupled with multiple-angle laser light scattering, NMR, and Fourier transform infrared spectroscopy. The self-assembly and thermoreversible gel formation in the helicogenic solvent toluene is investigated by transmission electron microscopy, atomic force microscopy, small-angle X-ray scattering, and synchrotron powder X-ray diffraction. At concentrations significantly below the minimum gelation concentration, spherical aggregates are observed. At higher concentrations, gels are formed, which show a 3D network structure composed of nanofibers. The proposed self-assembly mechanism is based on a distorted hexagonal packing of PBLG helices parallel to the axis of the nanofiber. The gel network forms due to branching and rejoining of bundles of PBLG nanofibers. The network exhibits uniform domains with a length of 200±42 nm composed of densely packed PBLG helices. KW - Poly(gamma-benzyl-L-glutamate) (PBLG) KW - Nickel-mediated NCA polymerization KW - Thermoreversible gel formation KW - Physical/supramolecular organogel KW - Nanofiber KW - Self-assembly KW - Alpha-helix KW - Nanotechnology KW - Small-angle X-ray scatering KW - SAXS PY - 2013 DO - https://doi.org/10.1007/s00396-012-2866-9 SN - 0303-402X SN - 1435-1536 VL - 291 IS - 6 SP - 1353 EP - 1363 PB - Springer CY - Berlin AN - OPUS4-28615 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -