TY - JOUR A1 - Hoffmann, Katrin A1 - Dietzel, B. A1 - Schulz, B. A1 - Reck, Günter A1 - Hoffmann, Angelika A1 - Orgzall, I. A1 - Resch-Genger, Ute A1 - Emmerling, Franziska T1 - Combined structural and fluorescence studies of methyl-substituted 2,5-diphenyl-1,3,4-oxadiazoles - relation between electronic properties and packing motifs JF - Journal of molecular structure N2 - Prerequisite for the rational design of functional organic materials with tailor-made electronic properties is the knowledge of the structure–property relationship for the specific class of molecules under consideration. This encouraged us to systematically study the influence of the molecular structure and substitution pattern of aromatically substituted 1,3,4-oxadiazoles on the electronic properties and packing motifs of these molecules and on the interplay of these factors. For this purpose, seven diphenyl-oxadiazoles equipped with methyl substituents in the ortho- and meta-position(s) were synthesized and characterized. Absorption and fluorescence spectra in solution served here as tools to monitor substitution-induced changes in the electronic properties of the individual molecules whereas X-ray and optical measurements in the solid state provided information on the interplay of electronic and packing effects. In solution, the spectral position of the absorption maximum, the size of Stokes shift, and the fluorescence quantum yield are considerably affected by ortho-substitution in three or four ortho-positions. This results in blue shifted absorption bands, increased Stokes shifts, and reduced fluorescence quantum yields whereas the spectral position and vibrational structure of the emission bands remain more or less unaffected. In the crystalline state, however, the spectral position and shape of the emission bands display a strong dependence on the molecular structure and/or packing motifs that seem to control the amount of dye–dye-interactions. These observations reveal the limited value of commonly reported absorption and fluorescence measurements in solution for a straightforward comparison of spectroscopic results with single X-ray crystallography. This underlines the importance of solid state spectroscopic studies for a better understanding of the interplay of electronic effects and molecular order. KW - Diphenyl-oxadiazoles KW - X-ray structure KW - Packing motif KW - Optical properties KW - Fluorescence quantum yield PY - 2011 DO - https://doi.org/10.1016/j.molstruc.2010.11.071 SN - 0022-2860 SN - 1872-8014 SN - 0377-046X VL - 988 IS - 1-3 SP - 35 EP - 46 PB - Elsevier CY - Amsterdam AN - OPUS4-23253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koshkina, Olga A1 - Bantz, C. A1 - Würth, Christian A1 - Lang, Thomas A1 - Resch-Genger, Ute A1 - Maskos, Michael T1 - Fluorophore-labeled siloxane-based nanoparticles for biomedical applications JF - Macromolecular symposia N2 - We present the synthesis and characterization of multifunctional fluorophore-labeled poly(organosiloxane) nanoparticles with core-shell architecture, where the fluorescent dye is incorporated into the core. Grafting of heterobifunctional poly(ethylene oxide) (PEO) onto the particle surface leads to water-soluble biocompatible nanoparticles. Two different strategies have been used for the synthesis: The encapsulation of dye-labeled monomers during the polycondensation with additional PEO coating and subsequent dye labeling by covalent attachment of the fluorescent dye rhodamine B to the (chloromethylphenyl)siloxane groups in the core after polymerization and grafting of PEO onto the surface. Comparison of the fluorescence quantum yields of the nanoparticles before and after PEO coating show a decrease in quantum yield after PEO coating. KW - Biocompatibility KW - Core-shell KW - Fluorescence KW - Fluorescence quantum yield KW - Nanoparticles KW - PEO PY - 2011 DO - https://doi.org/10.1002/masy.201100041 SN - 1022-1360 SN - 0258-0322 SN - 1521-3900 VL - 309/310 IS - 1 SP - 141 EP - 146 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-25143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Linck, Lena A1 - Kapusta, P. A1 - Resch-Genger, Ute T1 - Spectroscopic and photophysical properties of dUTP and internally DNA bound fluorophores for optimized signal detection in biological formats JF - Photochemistry and photobiology N2 - Efficient signal generation in DNA-based assays requires understanding of the influence of fluorophore’s interactions on the spectroscopic properties. The resulting changes in fluorescence intensity, quantum yield, emission anisotropy, and fluorescence lifetime provide straightforward tools for the study of molecular dynamics and interaction between labels and nucleic acids. Searching for bright fluorescent reporters for rolling circle amplification (RCA) as efficient signal enhancement strategy for biological formats, we investigated the spectroscopic properties of seven dyes: cyanines, rhodamines, and BODIPYs. They spectrally resemble Cy3, the most frequently used fluorophore in biodetection formats, and are measured in six samples (free dye, dye-dUTP, internally labeled ssDNA and dsDNA—single- and triple-labeled) using steady-state and time-resolved fluorometry. Special emphasis was dedicated to characterizing the nature of the interaction of these fluorophores differing in dye class, charge, and rigidity. Our results suggest dye charge and structure as main factors governing the dye’s interactions, with DY-555 and Cy3B presenting the best candidates for our envisaged signal amplification strategy. This label comparison underlines the importance of a proper understanding of structure-property relations and dye–biomolecule interactions for reporter choice and presents a road map towards the design and interpretation of experiments using these labels on DNA of known sequence. KW - DNA KW - Fluorescent dye KW - Fluorescence quantum yield KW - Cyanine KW - Rhodamine KW - Fluorescence lifetime KW - Guanosine quenching PY - 2012 DO - https://doi.org/10.1111/j.1751-1097.2012.01119.x SN - 0031-8655 SN - 1751-1097 VL - 88 IS - 4 SP - 867 EP - 875 PB - American Society for Photobiology CY - Augusta, Ga. AN - OPUS4-27080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Linck, Lena A1 - Resch-Genger, Ute T1 - Identification of efficient fluorophores for the direct labeling of DNA via rolling circle amplification (RCA) polymerase phi29 JF - European journal of medicinal chemistry N2 - The enzymatic incorporation as well as the spectroscopic properties and photochemical stability of a series of fluorescent labels differing in dye class, charge, and rigidity were studied to identify new tools for signal enhancement in situ on microarrays without secondary labeling. These fluorophores were chosen to spectrally match or resemble the golden standard Cy3. With the rhodamine DY-555, that is three times more emissive than Cy3, we found a bright and stable chromophore, the spectroscopic properties of which are minimally influenced by dye microenvironment. KW - Rolling circle amplification (RCA) KW - DNA KW - Fluorescent label KW - Fluorescence quantum yield KW - Cyanine KW - Stability PY - 2010 DO - https://doi.org/10.1016/j.ejmech.2010.09.005 SN - 0009-4374 SN - 0223-5234 VL - 45 IS - 12 SP - 5561 EP - 5566 PB - EDIFOR CY - Paris AN - OPUS4-22470 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Grabolle, Markus A1 - Brehm, Robert A1 - Spieles, Monika A1 - Hamann, F.M. A1 - Wenzel, M. A1 - Hilger, I. A1 - Resch-Genger, Ute T1 - Suitable labels for molecular imaging - influence of dye structure and hydrophilicity on the spectroscopic properties of IpG conjugates JF - Bioconjugate chemistry N2 - Aiming at the design of highly brilliant NIR emissive optical probes, e.g., for in vivo near-infrared fluorescence imaging (NIRF), we studied the absorption and fluorescence properties of the asymmetric cyanines Dy678, Dy681, Dy682, and Dy676 conjugated to the model antibody IgG. The ultimate goal was here to derive general structure–property relationships for suitable NIR fluorescent labels. These Dy dyes that spectrally match Cy5 and Cy5.5, respectively, were chosen to differ in chromophore structure, i.e., in the substitution pattern of the benzopyrylium end group and in the number of sulfonic acid groups. Spectroscopic studies of the free and IgG-bound fluorophores revealed a dependence of the obtained dye-to-protein ratios on dye hydrophilicity and control of the fluorescence quantum yields (Φf) of the IgG conjugates by the interplay of different fluorescence reduction pathways like dye aggregation and fluorescence resonance energy transfer (FRET). Based upon aggregation studies with these dyes, the amount of dye dimers in the IgG conjugates was determined pointing to dye hydrophilicity as major parameter controlling aggregation. To gain further insight into the exact mechanism of dye dimerization at the protein, labeling experiments at different reaction conditions but constant dye-to-protein ratios in the reaction solution were performed. With Dy682 that displays a Φf of 0.20 in PBS and 0.10 for moderate dye-to-protein ratio of 2.5, a low aggregation tendency, and a superior reactivity in IgG labeling, we identified a promising diagnostic tool for the design of NIR fluorescent probes and protein conjugates. KW - In vivo fluorescence imaging KW - NIR fluorophore KW - Fluorescence quantum yield KW - Cyanine KW - IpG KW - Protein labelling KW - Aggregation KW - Homo-FRET PY - 2011 DO - https://doi.org/10.1021/bc1004763 SN - 1043-1802 SN - 1520-4812 VL - 22 IS - 7 SP - 1298 EP - 1308 PB - ACS Publications CY - Washington, DC AN - OPUS4-24156 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Licha, K. A1 - Berkemeyer, Janis Manuel A1 - Grabolle, Markus A1 - Spieles, Monika A1 - Wegner, N. A1 - Welker, P. A1 - Resch-Genger, Ute T1 - New fluorescent labels with tunable hydrophilicity for the rational design of bright optical probes for molecular imaging JF - Bioconjugate chemistry N2 - The rational design of bright optical probes and dye–biomolecule conjugates in the NIR-region requires fluorescent labels that retain their high fluorescence quantum yields when bound to a recognition unit or upon interaction with a target. Because hydrophilicity-controlled dye aggregation in conjunction with homo-FRET presents one of the major fluorescence deactivation pathways in dye–protein conjugates, fluorescent labels are required that enable higher labeling degrees with minimum dye aggregation. Aiming at a better understanding of the factors governing dye–dye interactions, we systematically studied the signal-relevant spectroscopic properties, hydrophilicity, and aggregation behavior of the novel xS-IDCC series of symmetric pentamethines equipped with two, four, and six sulfonic acid groups and selected conjugates of these dyes with IgG and the antibody cetuximab (ctx) directed against the cancer-related epidermal growth factor (EGF) receptor in comparison to the gold standard Cy5.5. With 6S-IDCC, which displays a molar absorption coefficient of 190 000 M–1 cm–1 and a fluorescence quantum yield (Φf) of 0.18 in aqueous media like PBS and nearly no aggregation, we could identify a fluorophore with a similarly good performance as Cy5.5. Bioconjugation of 6S-IDCC and Cy5.5 yielded highly emissive targeted probes with comparable Φf values of 0.29 for a dye-to-protein (D/P) ratio <1 and a reduced number of protein-bound dye aggregates in the case of 6S-IDCC. Binding studies of the ctx conjugates of both dyes performed by fluorescence microscopy and FACS revealed that the binding strength between the targeted probes and the EGF receptor at the cell membrane is independent of D/P ratio. These results underline the importance of an application-specific tuning of dye hydrophilicity for the design of bright fluorescent reporters and efficient optical probes. Moreover, we could demonstrate the potential of fluorescence spectroscopy to predict the size of fluorescence signals resulting for other fluorescence techniques such as FACS. KW - Cyanine KW - Cetuximab KW - IgG KW - Protein labeling KW - Fluorescence quantum yield KW - Hydrophilicity KW - Dimerization constant PY - 2013 DO - https://doi.org/10.1021/bc4000349 SN - 1043-1802 SN - 1520-4812 VL - 24 IS - 7 SP - 1174 EP - 1185 CY - Washington, DC AN - OPUS4-29076 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Vag, T. A1 - Haag, R. A1 - Spieles, Monika A1 - Wenzel, M. A1 - Kaiser, W.A. A1 - Resch-Genger, Ute A1 - Hilger, I. T1 - An in vitro characterization study of new near infrared dyes for molecular imaging JF - European journal of medicinal chemistry N2 - The spectroscopic properties, stability, and cytotoxicity of series of cyanine labels, the dyes DY-681, DY-731, DY-751, and DY-776, were studied to identify new tools for in vivo fluorescence imaging and to find substitutes for DY-676 recently used by us as fluorescent label in a target-specific probe directed against carcinoembryonic antigen (CEA). This probe enables the selective monitoring of CEA-expressing tumor cells in mice, yet displays only a low fluorescence quantum yield and thus, a non-optimum sensitivity. All the DY dyes revealed enhanced fluorescence quantum yields, a superior stability, and a lower cytotoxicity in comparison to clinically approved indocyanine green (ICG). With DY-681 and far-red excitable DY-731 and DY-751, we identified three dyes with improved properties compared to DY-676 and ICG. KW - In vivo fluorescence imaging KW - NIR fluorophore KW - Cytotoxicity KW - Stability KW - Fluorescence quantum yield KW - Cyanine PY - 2009 DO - https://doi.org/10.1016/j.ejmech.2009.01.019 SN - 0009-4374 SN - 0223-5234 VL - 44 IS - 9 SP - 3496 EP - 3503 PB - EDIFOR CY - Paris AN - OPUS4-19712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -