Fluorescent enhancement

We detenuined the influence of oxy- and ketocarboxylic acids (succinate, fumarate, adipinate, a-ketoglutarate, isocitrate, tartrate, E-malate) on the luminescence intensity of the Eu-OxTc complex. These substances interact as polydentate ligands similarly to citrate with the formation of ternary complexes with Eu-OxTc. As to succinate, fumarate, adipinate and a-ketoglutarate this they cannot effectively coordinate with EiT+ and significant fluorescence enhancement was not observed. 

Several other techniques for have evolved for biochemical assays. In chapter 2 of this book, Omann and Sklar report on a method of fluoroimmunoassay where the bound and unbound antigen are separated by the quenching of fluorescence that accompanies antibody binding. Then, in chapter 3, Holl and Webb show how they achieved a sensitive measurement of nucleic acids by the enhancement in fluorescence that accompanies the binding of fluorescent dyes to nucleic acids. Chandler et al, also used fluorescence enhancement to monitor calcium mobility in neutrophil cells. 

Samples for studies of CDx effects on fluorescence enhancement in organic solution were prepared using pyrene, because pyrene possesses a long lifetime and is very susceptible to quenching and enhancement in solution (23). An aliquot of pyrene stock solution in cyclohexane was placed under a nitrogen purge to evaporate the cyclohexane. Samples were redissolved in a 1 A mixture of Isopropyl ether and 1-butanol, which was saturated with aqueous CDx solution. Pyrene samples were also prepared in which the organic solvent was not saturated with CDx solution. The mixed solvent was used in order to minimize the effects of ether evaporation and thus allow more accurate quantitation. Fluorescence measurements were made on diluted samples of these solutions. The solvent used to make up the... 

Fig. 3.19 Sequence-specific fluorescence detection of DNA. (Top) Model of polyamide-TMR conjugate bound to DNA. In aqueous solutions, the hairpin polyamide-fluorophore displays fluorescence enhancement only upon binding to its match DNA site. Black and white spheres represent imidazole and pyrrole...

After hybridization and washing, the samples were stained with DAPI (4, 6-di-amidino-2-phenylindole), which apparently associates in the minor groove of double-stranded DNA (Kapuscinski 1990). DAPI from Sigma was used. Binding of DAPI to double-stranded DNA occurs with about a 20-fold fluorescence enhancement, which usually does not occur with single-stranded DNA (Haugland 1992). 

Contrary to the observations with TNP-ATP, however, Mg enhanced eosin fluorescence, whereas ions decreased the fluorescence enhancement of Mg and caused a fluorescence quench in the absence of added ions [99]. The fluorescence enhancement caused by Mg was explained by an increase in the number of eosin-binding sites. Fuller [98] on the other hand, has challenged this explanation and argued that only an increase in enhancement factor (i.e., movement of the fluorophore to a more hydrophobic region of the protein) can explain the Mg -induced fluorescence increase. 

Kuhn et al. observed the fluorescence enhancement and fluorescence decay rate of a single terrylene molecule when a spherical gold nanoparticle was approached to the... 

Mohamed, M. B., Volkov, V., Link, S. and El-Sayed, M. A. (2000) The lightning gold nanorods fluorescence enhancement of over a million compared to the gold metal. Chem. Phys. Lett., 317, 517-523. 

Uematsu, T., Maenosono, S. and Yamaguchi, Y. (2006) Photoinduced fluorescence enhancement in CdSe/ZnS quantum dot monolayers Influence of substrate. Appl. Phys. Lett., 89, 031910. 

It is well known that flnorescence from an RP-18 phase is much brighter than from a silica gel plate, because the coating of RP-18 material blocks nomadiative deactivation of the activated sample molecules. By spraying a TLC plate with a viscous liquid, e g., paraffin oil dissolved in hexane (20 to 67%), the fluorescence of a sample can be tremendously enhanced. The mechanism behind fluorescence enhancement is to keep molecules at a distance either from the stationary layer or from other sample molecules [14]. Therefore, not only paraffin oil, but a number of different molecules show this enhancement effect. 

The extent of fluorescence quenching often depends on the sorbent medium and is generally more severe for silica gel than for chemically bonded sorbents [183]. In many cases the emission signal can be enhanced by application of a viscous liquid to the layer before scanning the plate. Common fluorescence enhancing... 

Golgi-associated vesicle. Further improvements in fluorescence enhancement on binding at physiological pH are a stated target for further research. 

This is the first Cys fluorescent sensor derived from FONs, in which the fluorescence enhancing property is in conjunction with a remarkable red-shifted fluorescence emission. Despite the potential sources of error when considering complicated clinical samples, the authors believe that this probe can be applied to study the effects of Cys in a biological system. 

Gruber HJ, Hahn CD, Kada G, Riener CK, Harms GS, Ahrer W, Dax TG, Knaus HG (2000) Anomalous fluorescence enhancement of Cy3 and Cy3.5 versus anomalous fluorescence loss of Cy5 and Cy7 upon covalent linking to IgG and noncovalent binding to avidin. Bioconjugate Chem 11 696-704... 

Matveeva EG, Terpetschnig EA, Stevens M, Patsenker L, Kolosova OS, Gryczynski Z, Gryczynski I (2009) Near-infrared squaraine dyes for fluorescence enhanced surface assay. Dyes Pigm 80 41 16... 

Humphry-Baker R, Gratzel M, Steiger R (1980) Drastic fluorescence enhancement and photochemical stabilization of cyanine dyes through micellar systems. J Am Chem Soc 102(2) 847-848... 

Yokoe H, Meyer T (1996) Spatial dynamics of GFP-tagged proteins investigated by local fluorescence enhancement. Nat Biotechnol 14 1252-1256... 

Howard [27] determined dissolved aluminium in seawater by the micelle-enhanced fluorescence of its lumogallion complex. Several surfactants (to enhance fluorescence and minimise interferences), used for the determination of aluminium at very low concentrations (below 0.5 pg/1) in seawaters, were compared. The surfactants tested in preliminary studies were anionic (sodium lauryl sulfate), non-ionic (Triton X-100, Nonidet P42, NOPCO, and Tergital XD), and cationic (cetyltrimethylammonium bromide). Based on the degree of fluorescence enhancement and ease of use, Triton X-100 was selected for further study. Sample solutions (25 ml) in polyethylene bottles were mixed with acetate buffer (pH 4.7, 2 ml) lumogallion solution (0.02%, 0.3 ml) and 1,10-phenanthroline (1.0 ml to mask interferences from iron). Samples were heated to 80 °C for 1.5 h, cooled, and shaken with neat surfactant (0.15 ml) before fluorescence measurements were made. This procedure had a detection limit at the 0.02 pg/1 level. The method was independent of salinity and could therefore be used for both freshwater and seawater samples. 

Hydrogen peroxide was determined with fmol detection limits by using rhodamine 6G and pyrimidopyrimidine derivatives as fluorescent enhancers. The method employing the latter reagent was applied to cola drinks [92], Sensitive... 

AND gate 4 differs from 3 in several aspects of performance and design. Experimentally, 4 produces a virtually perfect truth table The output logic 1 state has a fluorescence quantum yield (< >f) of 0.22 and the three logic 0 states do not rise above a cj>f value of 0.009. A fluorescence enhancement (FE) factor exceeding an order of magnitude such as this is a joy to work with since the switching phenomena are so clearly visible. 

H.D. Burrows, Y.M.M. Lobo, J. Pina, M.L. Ramos, J.S. de Melo, A.J.M. Yelente, M.J. Tapia, S. Pradhan, and U. Scherf, Fluorescence enhancement of the water-soluble poly l,4-phenylene-[9,9-bis(4-phenoxybutylsulfonate) ]fluorene-2,7-diyl copolymer in M-dodecylpentaoxyethylene glycol ether micelles, Macromolecules, 37 7425-7427, 2004. 

The fluorescence spectra of the monomeric cyanine nucleic acid stains family (PO-PRO-1, BO-PRO-1 and YO-PRO-1) introduced by Molecular Probes (http // probes.invitrogen.com) cover the entire visible wavelength range. These dyes may also be used with ultraviolet trans- or epi-illuminator excitation sources. The monomeric cyanine nucleic acid stains exhibit large degrees of fluorescence enhancement upon binding to DNA (or RNA) up to 1,800-fold. Consequently,... 

Fig. 3 Typical ICT probes (left) and representative spectroscopic responses toward selected metal ions (right). Color code (left) coordinating atoms in blue, bridgehead atom of the fluorophore that takes part in complexation in orange, formal donor fragment in red, formal acceptor fragment in green (right) hypsochromic shifts in red, bathochromic shifts in green, fluorescence enhancement in violet, fluorescence quenching in blue. Symbols in table Aabs, 7em,

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