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Fluorescence Quenchers (fluorescence + quencher)
Selected AbstractsSimple PbII fluorescent probe based on PbII -catalyzed hydrolysis of phosphodiesterBIOPOLYMERS, Issue 6 2003Ming Sun Abstract A new fluorescent probe for PbII, p -nitrophenyl 3H -phenoxazin-3-one-7-yl phosphoric acid (NPPA), was designed and synthesized by linking resorufin (serving as a fluorophore and electron acceptor) to p -nitrophenol (serving as a fluorescence quencher and electron donor) through phosphodiester bonds. When NPPA was irradiated with light, intramolecular fluorescence self-quenching took place because of the photoinduced electron transfer from the donor to the acceptor. However, upon the addition of PbII, the phosphate ester bonds in the probe were cleaved and the fluorophore was released, accompanying the retrievement of fluorescence. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy), 2003 [source] Anthraquinones as Artificial DNA Building BlocksEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2008Nicolas Bouquin Abstract Synthesis and properties of oligodeoxynucleotides containing anthraquinone-derived building blocks with flexible linkers are described. Starting from the 1,4-, 1,5-, 1,8- and 2,6-dihydroxyanthraquinone isomers, the corresponding phosphoramidites were prepared and incorporated into oligonucleotides. The site of linker attachment was found to be of critical importance for hybrid stability. Whereas the 2,6-isomer led to a significant stabilization, all other isomers had a negative effect on the stability of the duplex. Spectroscopic studies showed that the anthraquinones behave as fluorescence quenchers. Models of anthraquinone-modified double-stranded hybrids are proposed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] A Smart Nanoprobe Based On Fluorescence-Quenching PEGylated Nanogels Containing Gold Nanoparticles for Monitoring the Response to Cancer TherapyADVANCED FUNCTIONAL MATERIALS, Issue 6 2009Motoi Oishi Abstract A biocompatible, caspase-3-responsive, and fluorescence-quenching smart apoptosis nanoprobe based on a PEGylated nanogel that contains gold nanoparticles (GNPs) (fluorescence quenchers) in the cross-linked polyamine gel core and fluorescein isothiocyanate (FITC)-labeled DEVD peptides at the tethered PEG chain ends is prepared for monitoring the cancer response to therapy. FITC,DEVD,nanogel,GNP shows very little fluorescence in the absence of activated caspase-3 (normal cells) through the fluorescence resonance energy transfer (FRET) process between the GNPs and the FITC molecules, while pronounced fluorescence signals are observed in apoptotic cells because of the cleavage of the DEVD peptide by activated caspase-3 present in the cells, which results in the release of FITC molecules. Thus, remarkable quenching and dequenching of fluorescence signals in response to activated caspase-3 is observed. Apoptotic cells are detected in human hepatocyte (HuH-7) multicellular tumor spheroids (MCTSs), a commonly used three-dimensional in vitro model mimicking the in vivo biology of tumors, as early as one day post-treatment with staurosporine, an apoptosis-inducing agent; while growth inhibition (i.e., change in size) of the HuH-7 MCTSs is only observed after a delay of three days (i.e., on day 4). This demonstrates the effectiveness of the FITC,DEVD,nanogel,GNP probe as a smart nanoprobe for real-time monitoring as well as a more rapid assessment of the early response to cancer therapy. [source] Trifluoroethanol and binding to model membranes stabilize a predicted turn in a peptide corresponding to the first extracellular loop of the angiotensin II AT1A receptorBIOPOLYMERS, Issue 1 2002Roberto K. Salinas Abstract Homology modeling of the angiotensin II AT1A receptor based on rhodopsin,s crystal structure has assigned the 92,100 (YRWPFGNHL) sequence of the receptor to its first extracellular loop. Solution and membrane-bound conformational properties of a peptide containing this sequence (EL1) were examined by CD, fluorescence, and 1H-NMR. CD spectra in aqueous solution revealed an equilibrium between less organized and folded conformers. NMR spectra indicated the coexistence of trans and cis isomers of the Trp3,Pro4 bond. A positive band at 226 nm in the CD spectra suggested aromatic ring stacking, modulated by EL1's ionization degree. CD spectra showed that trifluoroethanol (TFE), or binding to detergent micelles and phospholipid bilayers, shifted the equilibrium toward conformers with higher secondary structure content. Different media gave rise to spectra suggestive of different ,-turns. Chemical shift changes in the NMR spectra corroborated the stabilization of different conformations. Thus, environments of lower polarity or binding to interfaces probably favored the formation of hydrogen bonds, stabilizing ,-turns, predicted for this sequence in the whole receptor. Increases in Trp3 fluorescence intensity and anisotropy, blue shifts of the maximum emission wavelength, and pK changes also evinced the interaction between EL1 and model membranes. Binding was seen to depend on both hydrophobic and electrostatic interactions, as well as lipid phase packing. Studies with water-soluble and membrane-bound fluorescence quenchers demonstrated that Trp3 is located close to the water,membrane interface. The results are discussed with regard to possible implications in receptor folding and function. © 2002 Wiley Periodicals, Inc. Biopolymers 65: 21,31, 2002 [source] | ||||||||||