title: Glycerol-based contrast agents: a novel series of dendronized pentamethine dyes.
abstract: The synthesis of water-soluble dyes, which absorb and emit in the range between 650 and 950 nm and display high extinction coefficients (ε) as well as high fluorescence quantum yields (Φf), is still a demand for optical imaging. We now present a synthetic route for the preparation of a new group of glycerol-substituted cyanine dyes from dendronized indole precursors that have been functionalized as N-hydroxysuccinimide (NHS) esters. High Φf values of up to 0.15 and extinction coefficients of up to 189 000 L mol(-1) cm(-1) were obtained for the pure dyes. Furthermore, conjugates of the new dendronized dyes with the antibody cetuximab (ctx) that were directed against the epidermal growth factor receptor (EGFR) of tumor cells could be prepared with dye to protein ratios between 0.3 and 2.2 to assess their potential as imaging probes. For the first time, ctx conjugates could be achieved without showing a decrease in Φf and with an increasing labeling degree that exceeded the value of the pure dye even at a labeling degree above 2. The incorporation of hydrophilically and sterically demanding dendrimers into cyanines prevented dimer formation after covalent conjugation to the antibody. The binding functionality of the resulting ctx conjugates to the EGFR was successfully demonstrated by cell microscopy studies using EGFR expressing cell lines. In summary, the combination of hydrophilic glycerol dendrons with reactive dye labels has been established for the first time and is a promising approach toward more powerful fluorescent labels with less dimerization.
authors: †Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
authors: Virginia
authors: V
authors: Wycisk
authors: ‡BAM Federal Institute for Material Research and Testing, Division Biophotonics, 12489 Berlin, Germany.
authors: Jutta
authors: J
authors: Pauli
authors: §mivenion GmbH, Robert-Koch-Platz 4, D-10115 Berlin, Germany.
authors: Pia
authors: P
authors: Welker
authors: †Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
authors: Aileen
authors: A
authors: Justies
authors: ‡BAM Federal Institute for Material Research and Testing, Division Biophotonics, 12489 Berlin, Germany.
authors: Ute
authors: U
authors: Resch-Genger
authors: †Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
authors: Rainer
authors: R
authors: Haag
authors: §mivenion GmbH, Robert-Koch-Platz 4, D-10115 Berlin, Germany.
authors: Kai
authors: K
authors: Licha
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology; D002232:Carbocyanines / Q000737:chemistry*; D045744:Cell Line, Tumor; D000068818:Cetuximab / Q000737:chemistry / Q000494:pharmacology; D003287:Contrast Media / Q000138:chemical synthesis* / Q000737:chemistry; D050091:Dendrimers / Q000737:chemistry*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D015870:Gene Expression; D005990:Glycerol / Q000737:chemistry*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D018796:Immunoconjugates / Q000737:chemistry / Q000494:pharmacology; D007211:Indoles / Q000737:chemistry; D008856:Microscopy, Fluorescence; D061848:Optical Imaging; D013194:Staining and Labeling / Q000379:methods
chemical_list: D000970:Antineoplastic Agents; D002232:Carbocyanines; D003287:Contrast Media; D050091:Dendrimers; D005456:Fluorescent Dyes; D018796:Immunoconjugates; D007211:Indoles; C512478:EGFR protein, human; D066246:ErbB Receptors; D005990:Glycerol; D000068818:Cetuximab