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 - 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 -