Fluorene labeling

Fluorene labeling simple labeling requires specific antibody AAF carcinogenic... 

Intensive effort has been devoted to the optimization of CCP structures for improved fluorescence output of CCP-based FRET assays. The inherent optoelectronic properties of CCPs make PET one of the most detrimental processes for FRET. Before considering the parameters in the Forster equation, it is of primary concern to reduce the probability of PET. As the competition between FRET and PET is mainly determined by the energy level alignment between donor and acceptor, it can be minimized by careful choice of CCP and C. A series of cationic poly(fluorene-co-phenylene) (PFP) derivatives (IBr, 9, 10 and 11, chemical structures in Scheme 8) was synthesized to fine-tune the donor/acceptor energy levels for improved FRET [70]. FI or Tex Red (TR) labeled ssDNAg (5 -ATC TTG ACT ATG TGG GTG CT-3 ) were chosen as the energy acceptor. The emission spectra of IBr, 9, 10 and 11 are similar in shape with emission maxima at 415, 410, 414 and 410 nm, respectively. The overlap between the emission of these polymers and the absorption of FI or TR is thus similar. Their electrochemical properties were determined by cyclic voltammetry experiments. The calculated HOMO and LUMO... 

Liu B, Dan TTT, Bazan GC (2007) Collective response from a cationic tetrahedral fluorene for label-free DNA detection. Adv Funct Mater 17 2432-2438... 

We employed various substrates to check for MFO in two bivalve species, a salt water mussel (Mytilus edulis) and a fresh water clam (Anodonta sp). Cytochrome P-450 was also studied. Organisms were exposed to 100 PPM Venezuelan crude in a stagnant system for up to one month. Enzyme assays were carried out with digestive gland 9000 g homogenates (17) and cytochrome P-450 analysis, with microsomes (21). The hydrocarbon substrates investigated included 1I+C-labelled benzo(a)pyrene, fluorene, anthracene, and naphthalene. The method used for separation of BP metabolites by thin layer radiochromatography has been described (7). The metabolite detection method for the other aromatic hydrocarbons was essentially the same except methylene chloride was used as metabolite extractant as well as TLC developer. Besides the hydrocarbon substrates, we also checked for other MFO reactions, N-dealkylase with C-imipramine (22) and 0-dealkylase with ethoxycoumarin (15). 

Fig. 3 TFB F8BT structures (slightly tilted forward) showing two different orientations of the polymer constituents. In each, the FBT (top chain) consists of 3 fluorene (F) units and 3 benzothiadiazole (BT) units while the TFB (bottom chain) consists of 3 F units and 2 triarylamine (TB) units. These co-monomer units are labeled with indices. The eclipsed orientation (panel a) has the middle F units (F12 and F22) of both chains 7r-stacked while the staggered orientation (panel b) has the middle BT of FBT (BT2) and the middle F of TFB (F22) 7r-stacked, see Eqs. (l)-(2). Reprinted with permission from Ref. [41]. Copyright 2007, American Institute of Physics.

Bioaccumulatlon of some pesticides (fenitrothion, aminocarb, permethrin) with real or potential application in forestry in Canada has been examined in laboratory experiments using larval rainbow trout and common duckweed. Bioaccumulation of an aromatic hydrocarbon, fluorene, has also been examined since some commercial formulations employ hydrocarbon solvents. Laboratory exposures of fish or plants were carried out by placing the organisms in dilute aqueous solutions of C labelled pesticide or hydrocarbon, and by measuring transfer of radioactivity from water to fish or plants. After transfer of fish or plants to untreated water, loss of radioactivity was measured similarly. These measures allowed calculation of uptake and depuration rate constants which were used to predict residue accumulations under various exposure conditions. Predicted residue accumulations agreed substantially with other predictive equations in the literature and with reported field observations. 

Chemical materials. Ring-labelled C fenitrothion was supplied by the Sumitomo Chemical Co., Osaka, Japan (20.23 uCi/uM). Aminocarb was obtained from Mobay Chemical Co., Kansas City, Mo., USA, as ring-labelled C material (11.7 uCi/uM). Cis- and trans- permethrin were synthesized as methylene- C compounds (59.7 uCi/uM), or as cyclopropyl- C compounds (50 uCi/uM) by ICI Ltd., Jealotts Hill, UK. Fluorene was purchased as 9- C material from California Bionuclear Corp. (2.61 uCi/uM). 

Bioconcentration of organic compounds by aquatic plants has received relatively little research attention. Curves showing uptake and loss of radioactivity by duckweed plants exposed to labelled compounds in axenic cultures are shown in Fig. 2. Rate constants and calculated equilibrium bioconcentration factors are shown in Table III. By comparison with fish data shown in Table I, the plants concentrated fenitrothion and fluorene rather poorly, and aminocarb surprisingly well. Lockhart et al. (14) presented a regression equation based on data from uptake curves ... 

Similar to the case with fish, we are not aware of field studies with fluorene in plants. Figure 2 shows the very rapid depuration of label from duckweed in culture, resulting in the high K2 (Table III) and the short half-life (Table V). In view of the volatility of fluorene, and its short half-life it would not be expected to persist long in plants after a spray with a solvent containing fluorene. McLeese et al. (27) examined the uptake and depuration of "585 oil by mussels and found a similar result. The steady state bioconcentration factor was 160 but the half-life was only 0.3 days. 

Small Quantities. Wear goggles and protective gloves and clothing. Work in the fume hood. To 0.25 g of 2-acetylaminofluorene in a 50-mL round-bottom flask add 10 mL of concentrated hydrochloric acid. Fit the flask with a condenser and heat under reflux for at least 10 hours when all trace of yellow should have disappeared. Cool the contents of the flask to 0°C in an ice-salt bath and, over a period of 5 minutes, add dropwise a solution of 0.13 g of sodium nitrite in 0.3 mL of water. Stir the mixture for 30 minutes, then slowly add 2.7 mL of ice-cold 50% hypophosphorus acid. After stirring at room temperature for 16 hours, filter the mixture, wash the filtrate into the drain with water, and discard the solid (fluorene) with normal refuse or package and label for disposal by incineration.4-6... 

FIGURE 10.1. The chemical structure of poly -dialkyl-fluorene J-diyl). The positions of carbon atoms are labeled 1 through 13 and R=CnH2n+i. 

A set of fluorophores derived from naphthalene, phenanthrene, pyrene, phenazine and fluorene have been conjugated to the 5 -ends of DNA and RNA to compare their physico-chemical properties. Decreasing the Ji-electron density led to an enhancement in thermal stability, attributable to more favourable Jt-Ji interactions. Stability is further enhanced by using nitrated fluorophores. Fluorescent labelling of ODNs using oxyamino modified fluorescein has been reported by the incorporation into DNA of aldehyde functions. The aldehyde function was attached either at the 5 -end via a phosphate linker or internally via 8-mercaptobutanal. Reduction of the resulting oxime was not necessary. 

The mechanisms of these two cyclization reactions appear fairly different. While the xanthone synthesis would appear to follow a simple palladium migration/arylation mechanism, the fluoren-9-one synthesis has been subjected to isotope labeling experiments (Scheme 12), which indicate that more than one mechanistic pathway may apply. It turns out that the deuterium that replaces the iodide after palladium migration comes not only from the imidoyl position, but also from the pendent aromatic ring used to trap the migrated palladium via arylation. Such results can... 

Scheme 12 Isotope labeling experiments for the aryl to imidoyl palladium migration in the synthesis of fluoren-9-ones...

In a second set of experiments, the coal product from the initial [14C]fluorenyllithium and methyl iodide treatment was reacted with unlabeled fluorenyllithium and methyl iodide. Under this set of serial treatment conditions, run at two different isotopic enrichments, as much as 40% (w/ w) of the isotopic label can be removed. The fate of the 14C label was established when the reaction byproducts, fluorene and 9-methylfluorene, were recovered and detected at the expected isotopic enrichment level. This important observation demonstrates that the incorporated reagent can be removed from the coal by chemical exchange and thus suggests a reversible reaction. 

The use of the blank serves to correct for the contributions that the retained fluorene makes to the spectra. This correction is most ideal when the total amount of fluorene is identical in the two samples and when methylated fluorene reagent makes only a minor contribution to the total spectral characteristics of the methylated sample. This situation is most closely approximated for the samples labeled blank and 1. This same condition does not hold for those samples labeled 2 and 3 because fluorene retention exceeds that of the blank sample. However, this perturbation will not affect the primary conclusions derived from the spectroscopic data. 

There is also evidence for the presence of fluorene-type derivatives in coal. The technique of selective methylation whereby an oxygen-methylated bituminous coal was treated with a series of carbanion bases followed by quenching with labeled methyl iodide appears to be a promising means of estimating the fluorene-type structural units in coal (Chambers et al., 1988) (Chapter 12). The data suggest that any molecular representations of coal structure should include the five-membered cyclopentadiene ring systems which are common to all fluorene derivatives. 

Franz, A.H. MoUnski, T.F. Lebrilla, C.B. MALDI-FTMS Characterization of oligosaccharides labelled with 9-amino-fluorene. J. Am. Soc. Mass Spectrom. 2001,12,1254-1261. 

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