Measurement of Large Proton Diffusion in Methanol-Doped Ice by Fluorescence Quenching of Riboflavin

2009 ◽  
Vol 113 (18) ◽  
pp. 7870-7881 ◽  
Author(s):  
Anna Uritski ◽  
Itay Presiado ◽  
Dan Huppert
Keyword(s):  
Fluorescence Quenching ◽  
Proton Diffusion

Fluorescence Quenching Reaction of Fenaminosulf with Acriflavine and Their Analytical Applications

2012 ◽  
Vol 29 (4) ◽  
pp. 440
Author(s):  
Yaqiong WANG ◽  
Shaopu LIU ◽  
Zhongfang LIU ◽  
Xiaoli HU
Keyword(s):  
Fluorescence Quenching ◽  
Analytical Applications

Characterization of Graphene Oxide Suspension for Fluorescence Quenching in DNA-Diagnostics

2016 ◽  
Vol 26 (1) ◽  
pp. 1-7 ◽  
Author(s):  
A.N. Kapitonov ◽  
G.N. Alexandrov ◽  
F.D. Vasileva ◽  
S.A. Smagulova ◽  
V.B. Timofeev ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Fluorescence Quenching ◽  
Dna Diagnostics

The Inhibition of Polysialyltranseferase ST8SiaIV Through Heparin Binding to Polysialyltransferase Domain (PSTD)

2019 ◽  
Vol 15 (5) ◽  
pp. 486-495 ◽  
Author(s):  
Li-Xin Peng ◽  
Xue-Hui Liu ◽  
Bo Lu ◽  
Si-Ming Liao ◽  
Feng Zhou ◽  
...  
Keyword(s):  
Fluorescence Quenching ◽  
Polysialic Acid ◽  
Neuronal Cell ◽  
Cd Spectroscopy ◽  
Migration And Invasion ◽  
Heparin Binding ◽  
Clinical Prognosis ◽  
Quenching Analysis ◽  
Different Types ◽  
Α Helix

Background:The polysialic acid (polySia) is a unique carbohydrate polymer produced on the surface Of Neuronal Cell Adhesion Molecule (NCAM) in a number of cancer cells, and strongly correlates with the migration and invasion of tumor cells and with aggressive, metastatic disease and poor clinical prognosis in the clinic. Its synthesis is catalyzed by two polysialyltransferases (polySTs), ST8SiaIV (PST) and ST8SiaII (STX). Selective inhibition of polySTs, therefore, presents a therapeutic opportunity to inhibit tumor invasion and metastasis due to NCAM polysialylation. Heparin has been found to be effective in inhibiting the ST8Sia IV activity, but no clear molecular rationale. It has been found that polysialyltransferase domain (PSTD) in polyST plays a significant role in influencing polyST activity, and thus it is critical for NCAM polysialylation based on the previous studies.Objective:To determine whether the three different types of heparin (unfractionated hepain (UFH), low molecular heparin (LMWH) and heparin tetrasaccharide (DP4)) is bound to the PSTD; and if so, what are the critical residues of the PSTD for these binding complexes?Methods:Fluorescence quenching analysis, the Circular Dichroism (CD) spectroscopy, and NMR spectroscopy were used to determine and analyze interactions of PSTD-UFH, PSTD-LMWH, and PSTD-DP4.Results:The fluorescence quenching analysis indicates that the PSTD-UFH binding is the strongest and the PSTD-DP4 binding is the weakest among these three types of the binding; the CD spectra showed that mainly the PSTD-heparin interactions caused a reduction in signal intensity but not marked decrease in α-helix content; the NMR data of the PSTD-DP4 and the PSTDLMWH interactions showed that the different types of heparin shared 12 common binding sites at N247, V251, R252, T253, S257, R265, Y267, W268, L269, V273, I275, and K276, which were mainly distributed in the long α-helix of the PSTD and the short 3-residue loop of the C-terminal PSTD. In addition, three residues K246, K250 and A254 were bound to the LMWH, but not to DP4. This suggests that the PSTD-LMWH binding is stronger than the PSTD-DP4 binding, and the LMWH is a more effective inhibitor than DP4.Conclusion:The findings in the present study demonstrate that PSTD domain is a potential target of heparin and may provide new insights into the molecular rationale of heparin-inhibiting NCAM polysialylation.

Nitrogen-doped carbon dots from Hutai-8 grape skin and their application in Hg2+ detection

2020 ◽  
Vol 16 ◽  
Author(s):  
Pan Zhang ◽  
Shun-Sheng Zhao ◽  
JiaJia Wang ◽  
Xiang Rong Liu
Keyword(s):  
Heavy Metal ◽  
Carbon Source ◽  
Fluorescence Quenching ◽  
Hydrothermal Method ◽  
Water Samples ◽  
Carbon Dots ◽  
Mercury Ions ◽  
Grape Skin ◽  
Fluorescent Carbon Dots ◽  
Fluorescent Carbon

Background: In recent years, environmental pollution and heavy metal pollution caused by rapid urbanization and industrialization have become increasingly serious. Among them, mercury (II) ion (Hg2+) is one of the highly toxic heavy metal ions, and its pollution comes from various natural resources and human activities. Therefore, people attach great importance to the development of analytical methods for effective analysis and sensitive detection of Hg2+ . Objective: Using grape skin as a green and environmental friendly carbon source, to synthesize fluorescent carbon dots, and try to apply them to the detect the concentration of Hg2+ in water. Method: Using "Hutai No. 8" grape skin as carbon source, fluorescent carbon dots were synthesized by one-step hydrothermal method. Structure and fluorescent properties of the carbon dots were tested using TEM, XPS, XRD and other characterization instruments, and their utilization on detection of mercury ions in the actual water samples was explored. Results: The CDs had a particle size of about 4.8 nm and a spherical shape. There are N-H, C-N, C=O and other functional groups on the surface. It was found that Hg2+ has obvious fluorescence quenching effect on CDs, and thus CDs fluorescence quenching method to detect the concentration Hg2+ was established, and the detection limit is 3.7 μM, which could be applied to test the concentration of Hg2+ in water samples. Conclusion: Using grape skin as carbon source, fluorescent carbon dots were successfully synthesized by hydrothermal method. Carbon dots were used to detect mercury ions in water, and a method for detecting mercury ions in actual water samples was established.

Formation of CT complexes and electron transfer from excited molecules of anthracene derivatives to methylviologen in aqueous and micellar media

1987 ◽  
Vol 52 (7) ◽  
pp. 1658-1665
Author(s):  
Viktor Řehák ◽  
Jana Boledovičová
Keyword(s):  
Electron Transfer ◽  
Complex Formation ◽  
Fluorescence Quenching ◽  
Rate Constant ◽  
Formation Constants ◽  
Dynamic Quenching ◽  
Micellar Media ◽  
Complex Formation Constants ◽  
Anthracene Derivatives ◽  
Ct Complexes

Disodium 1,5- and 1,8-anthracenedisulphonate (ADS) and 9-acetylanthracene form coloured CT complexes with methylviologen (MV2+) in aqueous and micellar media. The complex formation constants and molar absorptivities were determined by the Benesi-Hildebrandt method. In the fluorescence quenching, its static component plays the major role. The dynamic quenching component is determined by the rate constant of electron transfer from the S1 state of ADS to MV2+.

Fluorescence Quenching of Aminodiphenylamines with Chloromethanes

2002 ◽  
Vol 67 (8) ◽  
pp. 1154-1164 ◽  
Author(s):  
Nachiappan Radha ◽  
Meenakshisundaram Swaminathan
Keyword(s):  
Charge Transfer ◽  
Fluorescence Quenching ◽  
Ground State ◽  
Rate Constants ◽  
Quenching Mechanism ◽  
Quenching Rate ◽  
Charge Transfer Interaction ◽  
Electronically Excited ◽  
A Charge

The fluorescence quenching of 2-aminodiphenylamine (2ADPA), 4-aminodiphenylamine (4ADPA) and 4,4'-diaminodiphenylamine (DADPA) with tetrachloromethane, chloroform and dichloromethane have been studied in hexane, dioxane, acetonitrile and methanol as solvents. The quenching rate constants for the process have also been obtained by measuring the lifetimes of the fluorophores. The quenching was found to be dynamic in all cases. For 2ADPA and 4ADPA, the quenching rate constants of CCl4 and CHCl3 depend on the viscosity, whereas in the case of CH2Cl2, kq depends on polarity. The quenching rate constants for DADPA with CCl4 are viscosity-dependent but the quenching with CHCl3 and CH2Cl2 depends on the polarity of the solvents. From the results, the quenching mechanism is explained by the formation of a non-emissive complex involving a charge-transfer interaction between the electronically excited fluorophores and ground-state chloromethanes.

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