title: Bioconjugatable azo-based dark-quencher dyes: synthesis and application to protease-activatable far-red fluorescent probes.
abstract: We describe the efficient synthesis and one-step derivatization of novel, nonfluorescent azo dyes based on the Black Hole Quencher-3 (BHQ-3) scaffold. These dyes were equipped with various reactive and/or bioconjugatable groups (azido, α-iodoacetyl, ketone, terminal alkyne, vicinal diol). The azido derivative was found to be highly reactive in the context of copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions and allowed easy synthetic access to the first water-soluble (sulfonated derivative) and aldehyde-modified BHQ-3 dyes, the direct preparation of which failed by means of conventional azo-coupling reactions. The aldehyde- and α-iodoacetyl-containing fluorescence quenchers were readily conjugated to aminooxy- and cysteine-containing peptides by the formation of a stable oxime or thioether linkage, respectively. Further fluorescent labeling of the resultant peptide conjugates with red- or far-red-emitting rhodamine or cyanine dyes through sequential and/or one-pot bioconjugations, led to novel Förster resonance energy transfer (FRET) based probes suitable for the in vivo detection and imaging of urokinase plasminogen activator, a key protease in cancer invasion and metastasis.
authors.affiliation: Université de Rouen, Laboratory COBRA UMR 6014 & FR 3038, IRCOF, rue Lucien Tesnière, 76821 Mont-Saint-Aignan, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Chevalier
authors.forename: Cédrik
authors.initials: C
authors.lastname: Massif
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Renard
authors.forename: Anthony
authors.initials: A
authors.lastname: Romieu
mesh_terms: D001391:Azo Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D004396:Coloring Agents / Q000737:chemistry*; D003500:Cyclization; D003952:Diagnostic Imaging; D004789:Enzyme Activation; D005456:Fluorescent Dyes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010091:Oximes / Q000737:chemistry*; D010447:Peptide Hydrolases / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry*; D013451:Sulfonic Acids / Q000737:chemistry*
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D005456:Fluorescent Dyes; D010091:Oximes; D012235:Rhodamines; D013451:Sulfonic Acids; D010447:Peptide Hydrolases