TY - JOUR A1 - Behnke, Thomas A1 - Würth, Christian A1 - Hoffmann, Katrin A1 - Hübner, Martin A1 - Panne, Ulrich A1 - Resch-Genger, Ute T1 - Encapsulation of hydrophobic dyes in polystyrene micro- and nanoparticles via swelling procedures JF - Journal of fluorescence N2 - Aiming at the derivation of a generalized procedure for the straightforward preparation of particles fluorescing in the visible and near-infrared (NIR) spectral region, different swelling procedures for the loading of the hydrophobic polarity-probe Nile Red into nano- and micrometer sized polystyrene particles were studied and compared with respect to the optical properties of the resulting particles. The effect of the amount of incorporated dye on the spectroscopic properties of the particles was investigated for differently sized beads with different surface chemistries, i.e., non-functionalized, aminomodified and PEG-grafted surfaces. Moreover, photostability and leaking studies were performed. The main criterion for the optimization of the dye loading procedures was a high and thermally and photochemically stable fluorescence output of the particles for the future application of these systems as fluorescent labels. KW - Fluorescence KW - Nile red KW - Polystyrene KW - Nanoparticles KW - Microparticles KW - Encapsulation KW - Swelling PY - 2011 DO - https://doi.org/10.1007/s10895-010-0632-2 SN - 1053-0509 SN - 1573-4994 VL - 21 IS - 3 SP - 937 EP - 944 PB - Plenum Publ. Corp. CY - New York, NY AN - OPUS4-22692 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Behnke, Thomas A1 - Moser, Marko A1 - Nirmalananthan-Budau, Nithiya A1 - Resch-Genger, Ute T1 - Spectroscopic quantification of surface groups on micro- and nanoparticles N2 - Nanometer- and micrometer-sized particles are of increasing importance for a wide range of applications in the material and life sciences. This includes carriers for, e.g., drugs as well as dye molecules for use as multichromophoric reporters for signal enhancement in optical assays, platforms for DNA sequencing, and the fabrication of nanosensors and targeted probes for bioimaging studies. Application-relevant properties of such particles include their size (and size distribution), shape, colloidal stability, biocompatibility, and ease of subsequent functionalization, e.g., with linkers, sensor molecules, and targeting ligands. The latter requires knowledge of the number of groups effectively accessible for subsequent coupling reactions and hence, selective and sensitive methods of analysis, which can be ideally employed for the characterization of a broad variety of particle systems independent of their optical properties, i.e., scattering or the presence of encoding dyes. For product control, robust, reliable and fast methods performable with inexpensive equipment are prefered. In this respect, we studied a variety of conventional labels for optical readout, utilizing changes in intensity and/or color of absorption and/or emission. In addition, we developed a platform of cleavable and multimodal labels for optical assays which consist of a cleavable linker and an optically active reporter moiety. In contrast to conventional reporters measured directly at the particle surface, which are prone to signal distortions by scattering and encoding dyes, these cleavable labels can be detected colorimetrically or fluorometrically both bound at the particle surface and after quantitative cleavage of the linker in the transparent supernatant. Moreover, they enable straightforward validation by method comparison with elemental analysis, ICP-OES or ICP-MS. Here, we present representative examples of newly synthesized cleavable labels and their application for the quantification of amino, thiol and carboxy surface groups on different nanomaterials and compare these results with measurements using conventional optical labels. T2 - 253rd ACS National Meeting CY - San Francisco, CA, USA DA - 02.04.2017 KW - Nanoparticles KW - Microparticles KW - Surface groups KW - Quantification KW - Cleavable linker PY - 2017 N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. AN - OPUS4-40004 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Napp, J. A1 - Behnke, Thomas A1 - Fischer, L. A1 - Würth, Christian A1 - Wottawa, M. A1 - Katschinski, D.M. A1 - Alves, F. A1 - Resch-Genger, Ute A1 - Schäferling, M. T1 - Targeted luminescent near-infrared polymer-nanoprobes for in vivo imaging of tumor hypoxia JF - Analytical chemistry N2 - Polystyrene nanoparticles (PS-NPs) were doped with an oxygen-sensitive near-infrared (NIR)-emissive palladium meso-tetraphenylporphyrin and an inert reference dye which are both excitable at 635 nm. The nanosensors were characterized with special emphasis on fundamental parameters such as absolute photoluminescence quantum yield and fluorescence lifetime. The PS-NPs were employed for ratiometric dual-wavelength and lifetime-based photoluminescent oxygen sensing. They were efficiently taken up by cultured murine alveolar macrophages, yielding a characteristic and reversible change in ratiometric response with decreasing oxygen concentration. This correlated with the cellular hypoxic status verified by analysis of hypoxia inducible factor-1α (HIF-1α) accumulation. In addition, the surface of PS-NPs was functionalized with polyethylene glycol (PEG) and the monoclonal antibody herceptin, and their binding to HER2/neu-overexpressing tumor cells was confirmed in vitro. First experiments with tumor-bearing mouse revealed a distinctive ratiometric response within the tumor upon hypoxic condition induced by animal sacrifice. These results demonstrate the potential of these referenced NIR nanosensors for in vitro and in vivo imaging that present a new generation of optical probes for oncology. KW - Fluorescence KW - NIR KW - Nanoparticles KW - Microparticles KW - Imaging KW - Cancer KW - Oxygene PY - 2011 DO - https://doi.org/10.1021/ac201870b SN - 0003-2700 SN - 1520-6882 VL - 83 IS - 23 SP - 9039 EP - 9046 PB - American Chemical Society CY - Washington, DC AN - OPUS4-24987 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -