• Journal of the Korean Chemical Society
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• v.42 no.1
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• pp.22-27
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• 1998

Fluorescence quenching of coumarin 153 and coumarin 481 with N,N-dimethylaniline in various solvents was investigated. Quenching rate constants are related to diffusion-limited rate constants to some extent. It is noted that smaller discrepancy was observed between the diffusion-limited rate constant and the experimental quenching rate constant when the stick boundary condition rather than the slip boundary condition was applied for estimating the diffusion coefficients. In nonpolar solvent like cyclohexane fluorescence quenching is adequately explained by the diffusion controlled process within the experimental error, but in acetonitrile the quenching rate constant was estimated to be consistently smaller than the diffusion limited rate constant. This may suggest that fluorescence quenching of coumarin dyes be affected not only by the molecular diffusion but also by the intramoleccular process such as charge separation.

• Journal of the Korean Chemical Society
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• v.56 no.5
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• pp.577-582
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• 2012

Quinine quantitative analysis, photo-bleaching, fluorescence quenching, and urine analysis have been performed by means of a UV-LED fluorometer, which can be easily built and used in a high-school laboratory. The quinine detection range is estimated to be 0.05-80 ppm, enough for many classroom luminescence experiments. The quinine content in commercial tonic water is determined from the calibration curve, and UV photo-bleaching of this anti-malarial drug is demonstrated with clear wavelength dependence. Halide quenching of quinine fluorescence is also observed and the increase in quenching efficiency in the order of $Cl^-$, $Br^-$, and $I^-$ is evident. Urine analyses for the student volunteers have been carried out and the results clearly reveal excretion of the ingested quinine. The student participants are exuberant throughout the course of this study and sense the practices resourceful.

• Genomics & Informatics
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• v.5 no.3
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• pp.113-117
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• 2007

The development of microarray technology has facilitated the understanding of gene expression profiles. Despite its convenience, the cause of dye-bias that confounds data interpretation in dual-color DNA microarray experiments is not well known. In order to economize time and money, it is necessary to identify the cause of dye bias, since designing dye-swaps to reduce the dye-specific bias tends to be very expensive. Hence, we sought to determine the reliable cause of systematic dye bias after treating murine macrophage RAW 264.7 cells with 2-keto-3-deoxyoctonate (KDO), interferon-beta $(IFN-{\beta})$, and 8-bromoadenosine (8-BR). To find the cause of systematic dye bias from the point of view of fluorescence quenching, we examined the correlation between systematic dye bias and the proportion of each nucleotide in mRNA and oligonucleotide probe sequence. Cy3-dye bias was highly correlated with the proportion of adenines. Our results support the fact that systematic dye bias is affected by fluorescence quenching of each feature. In addition, we also found that the strength of fluorescence quenching is based on not only dye-dye interactions but also dye-nucleotide interactions as well.

• Journal of Photoscience
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• v.11 no.1
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• pp.11-17
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• 2004

Fluorescence quenching of l,4-bis [2-(2-methylphenyl) ethenyl]-benzene (Bis-MSB) by carbon tetrachloride in five different solvents namely hexane, cyclohexane, toluene, benzene and dioxane has been carried out at room temperature with a view to understand the quenching mechanisms. The Stern-Volmer plot has been found to be non-linear with a positive deviation for all the solvents studied. In order to interpret these results we have invoked the Ground state complex and Sphere of action static quenching models. Using these models various rate parameters have been determined. The magnitudes of these parameters imply that sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation in the Stem-Volmer plots is attributed to the static and dynamic quenching. Further, with the use of Finite Sink approximation model, it was possible to check whether these bimolecular reactions as diffusion limited and to estimate independently distance parameter R' and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R'and D with the values of the encounter distance R and the mutual diffusion coefficient D determined using the Edwardis empirical relation and Stokes-Einstein relation.

• Textile Coloration and Finishing
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• v.26 no.4
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• pp.277-282
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• 2014

Two tert-butyl substituted phthalocyanines(Pcs), in metal-free and metallated forms, were synthesized and the fluorescence responses toward various nitro derivatives, including picric acid(PA), 2,4-dinitrotoluene(DNT), 1,4-dinitrobenzene(DNB), 4-nitrotoluene(NT), nitrobenzene(NB), 1,4-benzoquinone(BQ), and nitromethane(NM) were investigated. Among the various nitro derivatives, current Pc derivatives exhibited efficient and exclusive fluorescence quenching in the presence of picric acid, which was readily observed by a naked eye. Quenching efficiency was estimated by the Stern-Volmer relationship, in which quenching constant, KSV, was calculated to be in the range of $10^4M^{-1}$. It was also found out that the aggregational behaviors of these Pcs are heavily dependent on the nature of solvent systems, subsequently affecting the quenching efficiency.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3593-3596
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• 2012

The water-soluble conjugated polymer with fluorescence quenching as a result of electrostatic interaction and aggregation was synthesized through Suzuki polymerization. The absorption and emission of anionic polymer (a-PFP) is blue shifted as compared with cationic polymer (c-PFP) although getting same backbone, and the absolute PL quantum efficiency of a-PFP in water is over 90% due to good solubility in aqueous solution. We anticipate that the fluorescence quenching of anionic and cationic polymers, with same conjugated backbone, could be shown in aqueous solution.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.519-523
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• 2011

We studied the detection of the Hg(II) concentration in an aqueous solution using rhodamine dyes on citrate-reduced Au nanoparticles (NPs). The quenching effect from Au NPs was found to decrease as the Hg(II) concentration increased under our experimental conditions. As the fluorescence signals intensified, the surface-enhanced Raman scattering (SERS) intensities reduced on the contrary due to less rhodamine dyes on Au NPs as the Hg(II) concentration increased. The rhodamine 6G (Rh6G) and rhodamine 123 (Rh123) dyes were examined via fluorescence and SERS measurements depending on Hg(II) concentrations. Fast and easy fluorescence detection of an Hg (II) concentration as low as a few ppm could be achieved by naked eye using citrate-reduced Au NPs.

• Nuclear Engineering and Technology
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• v.33 no.2
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• pp.166-174
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• 2001

An apparatus for detecting remote real-time uranium concentration using an optrode was developed. An optrode to detect uranium fluorescence as remote real-time control was designed. Fluorescence intensity at time 2ero was derived by the fluorescence signal processing and the algorithm to exclude the quenching effect of various quenchers and temperature fluctuations. This apparatus employing the above deriving method and the optrode has an error range within 6% in spite of serious fluorescence lifetime changes due to the quenching effect and temperature fluctuations. The detection limit is 0.06 ppm and the linearity is excellent between 0.06 ppm and 2 ppm on the aqueous uranium solution.

• Archives of Pharmacal Research
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• v.8 no.4
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• pp.205-211
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• 1985

The distribution of local anesthetics between the hydrocarbone interior and surface area of the lipid bilayer of liposomal membrane was calculated employeg fluorescence probe technique. The quenching of fluorescence probe technique. The quenching of fluorescence probe technique. The quenching of fluorescence of 12-(9-anthroyl) stearic acid and N-octadecyl naphthyl-2-amini-6-sulfonic acid by the local anesthetics in liposomal system was used to calculate the distribution. The Stern-Volmer equation was modified and employed for this calculation. The results showed that procaine hydrocloride and benzocaine were mainly distributed on the surface area of the lipid bilayer of the liposoal membrane, while tetracaine hydrochloride penetrated effectively into the hydrocarbon interior and showed even distribution in the lipid bilayer.

• Journal of Photoscience
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• v.12 no.1
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• pp.11-15
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• 2005

The mechanism of interaction of two drugs viz., amoxicillin and cloxacillin with bovine serum albumin has been investigated using fluorescence absorption and circular dichroism spectroscopy. The quenching mechanism of fluorescence of bovine serum albumin by amoxicillin and cloxacillin was discussed. The binding sites number n and apparent binding constant Kwere measured by fluorescence quenching method. The thermodynamic parameters obtained from data at different temperatures were calculated. The distance r between donor (bovine serum albumin) and acceptor (amoxicillin and cloxacillin) was obtained according to Forster theory of non-radiative energy transfer. The effect of common ions on binding constant was also investigated. The results of synchronous fluorescence spectra, UV-vis absorption spectra and circular dichroism of BSA in presence of amoxicillin and cloxacillin show that the conformation of bovine serum albumin changed