carbocyanines and pyrene

The efficacy of fluorescent hybridization assays is often limited by the low signal-to-background ratio of the probes that can be partially overcome by sophisticated signal amplification methods. Deep understanding of the mechanisms of fluorescence quenching and energy transfer in complex DNA probes and the choice of optimal donor/acceptor pairs along with rational design can significantly enhance the performance of DNA probes. Here, we proposed and studied novel Förster resonance energy transfer (FRET) dual DNA probes with the excimer-forming pyrene pair as a donor and sulfo-Cy3 dye as an acceptor, which demonstrated remarkable 75-fold enhancement of sulfo-Cy3 fluorescence upon target capturing. Stokes shift up to 220 nm minimizes fluorescence crosstalk. Time-correlated single-photon counting revealed two excited states of pyrene excimer wherein only one is directly involved in the resonance energy transfer to sulfo-Cy3. Optimized DNA probes demonstrated high sensitivity with excellent signal-to-background ratio, which were applied for visualization of 18S rRNA by fluorescent in situ hybridization in HEK-293T cells.

Topics: Carbocyanines; DNA Probes; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Molecular Structure; Pyrenes; RNA

Organic small-molecule-based photothermal agents such as cyanine dyes have received increasing attention in developing novel cancer therapies with potential clinical utility but suffer from poor stability, low photothermal efficiency, and limited accumulation at tumor sites in molecular forms. Self-assembly of small-molecule dyes into supramolecular assemblies may address these concerns by controlling the molecular organization of dye monomers to form structures of a higher order. Among them, H-aggregates of dyes favor face-to-face contacts with strongly overlapping areas, which always have a negative connotation to exhibit low or no fluorescence in most cases but may emanate energy in nonradiative forms such as heat for photothermal cancer therapy applications. Here, the synergistic self-assembly of cyanine dyes into H-aggregates is developed as a new supramolecular strategy to fabricate small-molecule-based photothermal nanomaterials. Compared to the free cyanine dyes, the H-aggregates assembled from pyrene or tetraphenylethene (TPE) conjugating cyanine exhibit the expected absorption spectral blue shift and fluorescence self-quenching but unique photothermal properties. Remarkably, the obtained H-aggregates are saucer-shaped nanoparticles that exhibit passive tumor-targeting properties to induce imaging-guided photothermal tumor ablation under irradiation. This supramolecular strategy presented herein may open up new opportunities for constructing next-generation small-molecule-based self-assembly nanomaterials for PTT cancer therapy in clinics.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Carbocyanines; Cell Line, Tumor; Female; Fluorescent Dyes; Mice; Mice, Nude; Particle Size; Photothermal Therapy; Pyrenes; Small Molecule Libraries; Stilbenes; Surface Properties

Vesicle-shaped supramolecular polymers are formed by self-assembly of a DNA duplex containing phenanthrene overhangs at both ends. In the presence of spermine, the phenanthrene overhangs act as sticky ends linking the DNA duplexes together. In aqueous solution, the assembly leads to vesicles with a diameter in the range of 50-200 nm. Fluorescence measurements show that the assembled phenanthrene units act as light-harvesting complexes and transfer absorbed energy to an acceptor, such as pyrene or Cy3, which can either be directly added to the polymer or attached via a complementary DNA strand. The presence of DNA in the nanostructures allows the construction of light-harvesting vesicles that are amenable to derivatization with different functional groups.

Topics: Base Sequence; Carbocyanines; DNA; Energy Transfer; Light; Models, Molecular; Nanocapsules; Phenanthrenes; Pyrenes

The supramolecular construction of multi-stimuli assemblies is a challenging task for prospective use. In this work, a novel supramolecular amphiphile was fabricated by introducing molecules with dynamic covalent bonds into host-guest inclusion. The amphiphile formed a vesicle, which was characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), 1H NMR and UV-vis spectra. Furthermore, the vesicular structure could be regulated by pH, light and redox reagent, and thus the loaded dye in the vesicles could be released in a controlled manner.

Topics: alpha-Cyclodextrins; Azo Compounds; Carbocyanines; Delayed-Action Preparations; Drug Compounding; Drug Liberation; Fluorescent Dyes; Hydrogen-Ion Concentration; Kinetics; Light; Oxidation-Reduction; Pyrenes; Surface-Active Agents

A light-harvesting system based on a DNA-organized oligopyrene-cyanine complex is described. Energy transfer from the pyrene units to the cyanine dye was found to proceed via FRET from locally confined excimers to the acceptor.

Topics: Carbocyanines; DNA; Energy Transfer; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Light-Harvesting Protein Complexes; Models, Molecular; Molecular Structure; Pyrenes