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Journal articles on the topic 'Fluorophore Quenching'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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1

Bae, Wooli, Tae-Young Yoon, and Cherlhyun Jeong. "Direct evaluation of self-quenching behavior of fluorophores at high concentrations using an evanescent field." PLOS ONE 16, no. 2 (February 19, 2021): e0247326. http://dx.doi.org/10.1371/journal.pone.0247326.

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The quantum yield of a fluorophore is reduced when two or more identical fluorophores are in close proximity to each other. The study of protein folding or particle aggregation is can be done based on this above-mentioned phenomenon—called self-quenching. However, it is challenging to characterize the self-quenching of a fluorophore at high concentrations because of the inner filter effect, which involves depletion of excitation light and re-absorption of emission light. Herein, a novel method to directly evaluate the self-quenching behavior of fluorophores was developed. The evanescent field from an objective-type total internal reflection fluorescence (TIRF) microscope was used to reduce the path length of the excitation and emission light to ~100 nm, thereby supressing the inner filter effect. Fluorescence intensities of sulforhodamine B, fluorescein isothiocyanate (FITC), and calcein solutions with concentrations ranging from 1 μM to 50 mM were directly measured to evaluate the concentration required for 1000-fold degree of self-quenching and to examine the different mechanisms through which the fluorophores undergo self-quenching.

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2

van der Velde, Jasper H. M., Jaakko J. Uusitalo, Lourens-Jan Ugen, Eliza M. Warszawik, Andreas Herrmann, Siewert J. Marrink, and Thorben Cordes. "Intramolecular photostabilization via triplet-state quenching: design principles to make organic fluorophores “self-healing”." Faraday Discussions 184 (2015): 221–35. http://dx.doi.org/10.1039/c5fd00114e.

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Covalent linkage of fluorophores and photostabilizers was recently revived as a strategy to make organic fluorophores “self-healing” via triplet-state quenching. Although Lüttke and co-workers pioneered this strategy already in the 1980s, the general design principles still remain elusive. In this contribution, we combine experiments and theory to understand what determines the photostabilization efficiency in dye–photostabilizer conjugates. Our results from single-molecule microscopy and molecular dynamics simulations of different Cy5-derivatives suggest that the distance and relative geometry between the fluorophore and photostabilizer are more important than the chemical nature of the photostabilizer, e.g. its redox potential, which is known to influence electron-transfer rates. We hypothesize that the efficiency of photostabilization scales directly with the contact rate of the fluorophore and photostabilizer. This study represents an important step in the understanding of the molecular mechanism of intramolecular photostabilization and can pave the way for further development of stable emitters for various applications.

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3

Canuel, Clelia, Sophie Badre, Henning Groenzin, Markus Berheide, and Oliver C. Mullins. "Diffusional Fluorescence Quenching of Aromatic Hydrocarbons." Applied Spectroscopy 57, no. 5 (May 2003): 538–44. http://dx.doi.org/10.1366/000370203321666560.

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The quenching of the fluorescence of five aromatic hydrocarbons by three halogenated organics and by molecular oxygen has been measured. Both fluorescence intensity and fluorescence lifetime measurements have been employed to validate results and interpretation; linear Stern–Volmer analyses are shown to apply throughout. The fluorescence quenching rate constant of molecular oxygen for the five aromatic hydrocarbons is essentially equivalent to the diffusion rate constant independent of the fluorophore excitation energy. The halogenated organic–fluorophore rate constants vary by a factor of 965 and are shown to correlate roughly with the energy difference between the quencher and fluorophore excited electronic states in accord with a standard model of quantum two-level mixing. The value of the coupling interaction energy is ∼2500 cm−1.

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4

McGregor, Nicholas, Christophe Pardin, and W. G. Skene. "Using Quenching Kinetics and Thermodynamics of Amino-Fluorophores as Empirical Tools for Predicting Boronic Acid Sensors Suitable for Use in Physiological Conditions." Australian Journal of Chemistry 64, no. 11 (2011): 1438. http://dx.doi.org/10.1071/ch11297.

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A series of water-soluble 1-amino-naphthalenes and 2-amino-fluorenes are prepared. These serve as model fluorophores for measuring the thermodynamics and kinetics of fluorescence quenching with phenylboronic acids and aliphatic amines. Steady-state and time-resolved fluorescence quenching kinetics are investigated using the Stern–Volmer method. Diffusion limited quenching constants and exergonic thermodynamics of electron transfer are derived for the 5-amino-1-napthol and 2-aminofluorene derivatives with phenylboronic acid and/or an aliphatic imine. No quenching and endergonic thermodynamics or electron transfer are observed for 5-sulfonamide, 5-sulfonic acid, or 5-hydroxy-7-sulfonic acid aminonaphthalene derivatives. Boronic acid sensors synthesized from these aminofluorophores by reductive amination with 2-formylphenylboronic acid undergo fluorescence revival in the presence of saccharides only when the fluorophore demonstrates diffusion limited quenching kinetics and exergonic thermodynamics of electron transfer with the boronic acid or imine quenchers. Thus, these two properties are suitable empirical tools for predicting saccharide-induced fluorescence revival of boronic acid sensors.

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5

Cha, Albert, and Francisco Bezanilla. "Structural Implications of Fluorescence Quenching in the Shaker K+ Channel." Journal of General Physiology 112, no. 4 (October 1, 1998): 391–408. http://dx.doi.org/10.1085/jgp.112.4.391.

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When attached to specific sites near the S4 segment of the nonconducting (W434F) Shaker potassium channel, the fluorescent probe tetramethylrhodamine maleimide undergoes voltage-dependent changes in intensity that correlate with the movement of the voltage sensor (Mannuzzu, L.M., M.M. Moronne, and E.Y. Isacoff. 1996. Science. 271:213–216; Cha, A., and F. Bezanilla. 1997. Neuron. 19:1127–1140). The characteristics of this voltage-dependent fluorescence quenching are different in a conducting version of the channel with a different pore substitution (T449Y). Blocking the pore of the T449Y construct with either tetraethylammonium or agitoxin removes a fluorescence component that correlates with the voltage dependence but not the kinetics of ionic activation. This pore-mediated modulation of the fluorescence quenching near the S4 segment suggests that the fluorophore is affected by the state of the external pore. In addition, this modulation may reflect conformational changes associated with channel opening that are prevented by tetraethylammonium or agitoxin. Studies of pH titration, collisional quenchers, and anisotropy indicate that fluorophores attached to residues near the S4 segment are constrained by a nearby region of protein. The mechanism of fluorescence quenching near the S4 segment does not involve either reorientation of the fluorophore or a voltage-dependent excitation shift and is different from the quenching mechanism observed at a site near the S2 segment. Taken together, these results suggest that the extracellular portion of the S4 segment resides in an aqueous protein vestibule and is influenced by the state of the external pore.

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6

Stella, Lorenzo. "Fluorescence Quenching, Lifetimes, and Fluorophore Solvent Accessibility." Journal of Chemical Education 88, no. 6 (June 2011): 695–96. http://dx.doi.org/10.1021/ed101147s.

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7

Kandela, Irawati K., Reiner Bleher, and Ralph M. Albrecht. "Multiple Correlative Immunolabeling for Light and Electron Microscopy Using Fluorophores and Colloidal Metal Particles." Journal of Histochemistry & Cytochemistry 55, no. 10 (October 2007): 983–90. http://dx.doi.org/10.1369/jhc.6a7124.2007.

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Multiple correlative immunolabeling permits colocalization of molecular species for sequential observation of the same sample in light microscoopy (LM) and electron microscopy (EM). This technique allows rapid evaluation of labeling via LM, prior to subsequent time-consuming preparation and observation with transmission electric miscroscopy (TEM). The procedure also yields two different complementary data sets. In LM, different fluorophores are distinguished by their respective excitation and emission wavelengths. In EM, colloidal metal nanoparticles of different elemental composition can be differentiated and mapped by energy-filtering transmission electron microscopy with electron spectroscopic imaging. For the highest level of spatial resolution in TEM, colloidal metal particles were conjugated directly to primary antibodies. For LM, fluorophores were conjugated to secondary antibodies, which did not affect the spatial resolution attainable by fluorescence microscopy but placed the fluorophore at a sufficient distance from the metal particle to limit quenching of the fluorescence signal. It also effectively kept the fluorophore at a sufficient distance from the colloidal metal particles, which resulted in limiting quenching of the fluorescent signal. Two well-defined model systems consisting of myosin and α-actinin bands of skeletal muscle tissue and also actin and α-actinin of human platelets in ultrathin Epon sections were labeled using both fluorophores (Cy2 and Cy3) as markers for LM and equally sized colloidal gold (cAu) and colloidal palladium (cPd) particles as reporters for TEM. Each sample was labeled by a mixture of conjugates or labels and observed by LM, then further processed for TEM. (J Histochem Cytochem 55: 983–990, 2007)

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8

Kandela, Irawati K., Reiner Bleher, and Ralph M. Albrecht. "Immunolabeling for Correlative Light and Electron Microscopy on Ultrathin Cryosections." Microscopy and Microanalysis 14, no. 2 (March 3, 2008): 159–65. http://dx.doi.org/10.1017/s1431927608080239.

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Correlative labeling permits colocalization of molecular species for observation of the same sample in light (LM) and electron microscopy (EM). Myosin bands in ultrathin cryosections were labeled using both fluorophore conjugated to secondary antibody (IgG) and colloidal gold (cAu) particles conjugated to primary IgG as reporters for LM and transmission electron microscopy (TEM), respectively. This technique allows rapid evaluation of labeling via LM, prior to more time-consuming observations with TEM and also yields two complementary data sets in one labeling procedure. Quenching of the fluorescent signal was inversely related to the distance between fluorophore and cAu particles. The signal from fluorophore conjugated to secondary antibody was inversely proportional to the size of cAu conjugated to primary antibody. Where fluorophore and cAu were bound to the same antibody, the fluorescence signal was nearly completely quenched regardless of fluorophore excitation or emission wavelength and regardless of particle size, 3 nm and larger. Colloidal metal particles conjugated to primary antibody provide high spatial resolution for EM applications. Fluorophore conjugated to secondary antibody provides spatial resolution well within that of conventional fluorescence microscopy. Use of fluorescent secondary antibody moved the fluorophore a sufficient distance from the cAu particles on the primary antibody to limit quenching of fluorescence.

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9

Olson, Kenneth R., Yan Gao, Faihaan Arif, Kanika Arora, Shivali Patel, Eric DeLeon, and Karl D. Straub. "Fluorescence quenching by metal centered porphyrins and poryphyrin enzymes." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 313, no. 4 (October 1, 2017): R340—R346. http://dx.doi.org/10.1152/ajpregu.00202.2017.

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Fluorescence spectroscopy and microscopy have been used extensively to monitor biomolecules, especially reactive oxygen species (ROS) and, more recently, reactive sulfide (RSS) species. Nearly all fluorophores are either excited by or emit light between 450 and 550 nm, which is similar to the absorbance of heme proteins and metal-centered porphyrins. Here we examined the effects of catalase (Cat), reduced and oxidized hemoglobin (Hb and metHb), albumin (alb), manganese (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP), iron protoporphyrin IX (hemin), and copper protoporphyrin IX (CuPPIX) on the fluorescence properties of fluorescein. We also examined the effects of catalase and MnTBAP on fluorophores for ROS (dichlorofluorescein, DCF), polysulfides (3′,6′-di( O-thiosalicyl)fluorescein, SSP4), and H2S (7-azido-4-methylcoumarin, AzMC) previously activated by H2O2, a mixed polysulfide (H2Sn, n = 1–7) and H2S, respectively. All except albumin concentration dependently inhibited fluorophore fluorescence and absorbed light between 450 and 550 nm, suggesting that the inhibitory effect was physical not catalytic. Catalase inhibition of fluorescein fluorescence was unaffected by sodium azide, dithiothreitol, diamide, tris(2-carboxyethyl)phosphine (TCEP), or iodoacetate, supporting a physical inhibitory mechanism. Catalase and TBAP augmented, then inhibited DCF fluorescence, but only inhibited SSP4 and AzMC fluorescence indicative of a substrate-specific catalytic oxidation of DCF and nonspecific fluorescence inhibition of all three fluorophores. These results suggest caution must be exercised when using any fluorescent tracers in the vicinity of metal-centered porphyrins.

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10

Kwak, Jinyoung, One Choi, Eunji Sim, and Sang-Yup Lee. "Evaluation of photoluminescence quenching for assessing the binding of nitroaromatic compounds to a tyrosyl bolaamphiphile self-assembly." Analyst 140, no. 15 (2015): 5354–60. http://dx.doi.org/10.1039/c5an00517e.

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11

Li, Qianyun, Yongmei Jia, Zongcai Feng, and Fang Liu. "A highly sensitive and selective fluorescent probe without quencher for detection of Pb2+ ions based on aggregation-caused quenching phenomenon." RSC Advances 8, no. 68 (2018): 38929–34. http://dx.doi.org/10.1039/c8ra07903j.

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12

Miao, Xiangmin, Zongbing Li, and Liansheng Ling. "Fluorescence recognition of double-stranded DNA based on the quenching of gold nanoparticles to a fluorophore labeled DNA probe." Analyst 141, no. 20 (2016): 5829–34. http://dx.doi.org/10.1039/c6an01145d.

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13

Herten, Dirk-Peter, Andreas Haderspeck, Felix Braun, and Hubert Wadepohl. "Copper(II)-induced Fluorescence Quenching of a BODIPY Fluorophore." Zeitschrift für anorganische und allgemeine Chemie 644, no. 14 (June 28, 2018): 735–39. http://dx.doi.org/10.1002/zaac.201800154.

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14

Raj, Vidya, and Sreenivasan Kunnetheeri. "Nonconjugated Polyelectrolyte as Efficient Fluorescence Quencher and Their Applications as Biosensors: Polymer-Polymer Interaction." ISRN Analytical Chemistry 2014 (January 22, 2014): 1–8. http://dx.doi.org/10.1155/2014/841857.

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A simple fluorescence quenching method for the quantitation in serum of an acute phase reactant, C-reactive protein (CRP), which can differentiate between viral and bacterial infections, is described, where material and reagent costs are minimal. The study harnesses a fluorescence quenching between a nonfluorescent polyelectrolyte containing a ligand (O-phosphorylethanolamine, PEA) and fluorophore (fluorescamine isomer 1) containing polyelectrolyte. The quenching was attributed due to strong polymer-polymer interaction through intermolecular hydrogen bonding. The nonlinear behaviour of Stern-Volmer plot indicates a binding induced quenching, that is, static quenching. However, fluorescence was found to increase in presence of C-reactive protein, due to the specific molecular recognition occurring between CRP and PEA, thereby excluding fluorophore containing chain. A definite correlation was found between concentration of CRP and fluorescence intensity and the method exhibited a linear relationship in the range of 40–360 ng/mL with a detection limit of 30 ± 2 ng/mL. The antibody free method was successfully applied for the analysis of CRP in human serum samples and the method showed good correlation with hospital measurements (y=1.0313x−0.1423; n=32; R=0.9998, P<0.0001). Thus the fluorescence based polyelectrolyte biosensor is a potential system for rapid, and antibody free platform for CRP detection.

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15

Kohlmann, Tim, and Martin Goez. "Combined static and dynamic intramicellar fluorescence quenching: effects on stationary and time-resolved Stern–Volmer experiments." Physical Chemistry Chemical Physics 21, no. 19 (2019): 10075–85. http://dx.doi.org/10.1039/c8cp07486k.

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It ain’t necessarily so—existing theories of combined quenching in micelles are flawed. We derive a consistent model, analyze its properties, and apply it to obtain information on ground-state complexes between fluorophore F and quencher Q.

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16

Zaharia, Marius, Gabi Drochioiu, Gheorghiță Zbancioc, and Vasile Robert Grădinaru. "Beyond Dinitrophenol Interaction with Tryptophan-Based Compounds." Acta Chemica Iasi 24, no. 1 (July 1, 2016): 43–49. http://dx.doi.org/10.1515/achi-2016-0004.

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Abstract The effects of 2,4-dinitrophenol (2,4-DNP) on the spectroscopic parameters (UV-Vis or FT-IR absorbance) or fluorescence emission of tryptophan and glycyl-tryptophan were studied. A quenching phenomenon of fluorescence was observed, attributed to interactions between the indole ring of the fluorophore and the aromatic ring of the quencher. The analysis of fluorescence spectra confirms that the quenching is dictated by 2,4-DNP concentration and pH. A combined mechanism of static and dynamic quenching was detected. The quenching phenomenon observed in this work could be employed to explain the mechanism of action of such compounds on large fluorescent peptides or proteins.

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17

Zhang, Wang, Xinye Zhao, Weijing Gu, Tian Cheng, Bingxiang Wang, Yuliang Jiang, and Jian Shen. "A novel naphthalene-based fluorescent probe for highly selective detection of cysteine with a large Stokes shift and its application in bioimaging." New Journal of Chemistry 42, no. 22 (2018): 18109–16. http://dx.doi.org/10.1039/c8nj04425b.

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An efficient naphthalene-based fluorescent probe (BTNA) for cysteine (Cys) has been rationally designed and synthesized in this work, which consists of a 6-(2-benzothiazolyl)-2-naphthalenol (BNO) fluorophore connected with an acrylate group (the fluorescence quenching and response group).

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18

Pinals, Rebecca, Darwin Yang, Alison Lui, Wendy Cao, and Markita P. Landry. "Biomolecule Exchange Dynamics on Carbon Nanotubes Via Multiplexed Fluorophore Quenching." ECS Meeting Abstracts MA2020-02, no. 7 (November 23, 2020): 1080. http://dx.doi.org/10.1149/ma2020-0271080mtgabs.

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19

Zheng, Qinsi, Steffen Jockusch, Gabriel G. Rodríguez-Calero, Zhou Zhou, Hong Zhao, Roger B. Altman, Héctor D. Abruña, and Scott C. Blanchard. "Intra-molecular triplet energy transfer is a general approach to improve organic fluorophore photostability." Photochemical & Photobiological Sciences 15, no. 2 (2016): 196–203. http://dx.doi.org/10.1039/c5pp00400d.

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20

Abnous, Khalil, Noor Mohammad Danesh, Mohammad Ramezani, Seyed Mohammad Taghdisi, and Ahmad Sarreshtehdar Emrani. "A novel amplified double-quenching aptasensor for cocaine detection based on split aptamer and silica nanoparticles." Analytical Methods 10, no. 26 (2018): 3232–36. http://dx.doi.org/10.1039/c8ay00755a.

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Herein, a sensitive and rapid fluorescent aptasensor was developed for the detection of cocaine as an illicit drug, based on an amplification strategy involving the use of silica nanoparticles coated with streptavidin (SNPs), double quenching of FAM fluorophore and cocaine split aptamer.

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21

Kim, Jimin P., Zhiwei Xie, Michael Creer, Zhiwen Liu, and Jian Yang. "Citrate-based fluorescent materials for low-cost chloride sensing in the diagnosis of cystic fibrosis." Chemical Science 8, no. 1 (2017): 550–58. http://dx.doi.org/10.1039/c6sc02962k.

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A new class of fluorescence chloride sensors are derived from a facile citrate-based synthesis platform, enabling low-cost chloride sensing for clinical diagnosis of Cystic Fibrosis through dynamic quenching mechanisms. We demonstrate for the first time a selective multi-halide sensing strategy using a single fluorophore.

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22

Wenska, Grażyna, and Stefan Paszyc. "Ground and excited-state interactions of coumarin and nucleotide base." Canadian Journal of Chemistry 66, no. 3 (March 1, 1988): 513–16. http://dx.doi.org/10.1139/v88-087.

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Steady-state and time-resolved fluorescence measurements for a series of bichromophoric compounds containing 7-methoxy-coumarin and nucleotide base residues have been performed in water and in organic solvents. The data from these studies have been used to calculate the relative proportion of folded and extended conformations of bichromophores. Ground-state stacking interactions of coumarin and nucleotide base have been found to be limited to aqueous solution. The contribution of the dynamic quenching mechanism to the total fluorescence quenching in water has been estimated. The absence of dynamic quenching in organic solvents is.explained on the basis of the very short lifetime of the fluorophore in methanol.

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23

Du, Hai Yan, Wei Da Xu, Wei Zhou, and Jia Yue Sun. "Effect of Deputy Group Metal Ions on the Fluorescent Properties of the CPPO-H₂O₂-Rhodamine B System." Materials Science Forum 663-665 (November 2010): 527–31. http://dx.doi.org/10.4028/www.scientific.net/msf.663-665.527.

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The influence of metal ions on the peroxyoxalate chemiluminescence reaction was investigated. A number of metal ions showed the quenching effect of the chemiluminescence reaction of bis (3, 5, 6- trichloro-2-carbopentyloxy) oxalate with hydrogen peroxide in the presence of Rhodamine B as the fluorophore. Copper ion gave the highest quenching effect. The reason for the decrease in the chemiluminescence intensity by metal ions is probably a change in the conjugative structure of Rhodamine B due to combination of metal ions and Rhodamine B

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24

Blatt, E., AWH Mau, WHF Sasse, and WH Sawyer. "Simulated Stern-Volmer Plots for 1-1 Ground-State Complexation." Australian Journal of Chemistry 41, no. 1 (1988): 127. http://dx.doi.org/10.1071/ch9880127.

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Stern-Volmer plots are simulated for the case of static quenching due to 1:1 ground-state complexation of quencher and fluorophore in solution, and compared with previously obtained experimental data. For cases where the association constant KC > 105 dm3 mol-1, upward curvatures of Stern- Volmer plots are expected. When KC is between 103 and 105 dm3 mol-1 linearity is obtained, while for KC < 103 dm3 mol-1 upward curvatures are again predicted. The significance of these results to fluorescence quenching experiments in general is discussed.

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25

Aich, Sanjukta, and Samita Basu. "Lifetime Quenching of the Fluorophore: A Signature of Magnetic Field Maximization." Photochemistry and Photobiology 70, no. 4 (1999): 602. http://dx.doi.org/10.1562/0031-8655(1999)070<0602:lqotfa>2.3.co;2.

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26

Aichf, Sanjukta, and Samita Basu. "Lifetime Quenching of the Fluorophore: A Signature of Magnetic Field Maximization." Photochemistry and Photobiology 70, no. 4 (October 1999): 602–6. http://dx.doi.org/10.1111/j.1751-1097.1999.tb08258.x.

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27

Hughes, Barbara K., Wade A. Braunecker, Andrew J. Ferguson, Travis W. Kemper, Ross E. Larsen, and Thomas Gennett. "Quenching of the Perylene Fluorophore by Stable Nitroxide Radical-Containing Macromolecules." Journal of Physical Chemistry B 118, no. 43 (October 20, 2014): 12541–48. http://dx.doi.org/10.1021/jp506240j.

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28

Grigoryan, K. R., H. A. Shilajyan, and V. A. Hovhannisyan. "BOVINE SERUM ALBUMIN FLUORESCENCE QUENCHING BY TANNIC ACID IN DIMETHYLSULFOXIDE CONTAINING SOLUTIONS." Proceedings of the YSU B: Chemical and Biological Sciences 54, no. 2 (252) (August 17, 2020): 99–104. http://dx.doi.org/10.46991/pysu:b/2020.54.2.099.

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Bovine serum albumin (BSA) interaction with tannic acid (TA) has been studied in dimethylsulfoxide (DMSO) aqueous solutions at different temperatures (293 and 303 K). To find out the fluorescence quenching mechanism of BSA in the presence of TA, the fluorescence data were analyzed according to the modified Stern-Volmer equation based on the approach of the existence of a “sphere of action” (a type of apparent static quenching). The values of apparent static and bimolecular quenching constants were calculated. The effect of DMSO and temperature on BSA–TA interactions is explained on the basis of structural changes in the “sphere of action” of the fluorophore due to the possible inclusion of DMSO molecules in this sphere.

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29

Smallwood, Chuck R., Lorne Jordan, Vy Trinh, Daniel W. Schuerch, Amparo Gala, Mathew Hanson, Yan Shipelskiy, Aritri Majumdar, Salete M. C. Newton, and Phillip E. Klebba. "Concerted loop motion triggers induced fit of FepA to ferric enterobactin." Journal of General Physiology 144, no. 1 (June 30, 2014): 71–80. http://dx.doi.org/10.1085/jgp.201311159.

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Spectroscopic analyses of fluorophore-labeled Escherichia coli FepA described dynamic actions of its surface loops during binding and transport of ferric enterobactin (FeEnt). When FeEnt bound to fluoresceinated FepA, in living cells or outer membrane fragments, quenching of fluorophore emissions reflected conformational motion of the external vestibular loops. We reacted Cys sulfhydryls in seven surface loops (L2, L3, L4, L5, L7 L8, and L11) with fluorophore maleimides. The target residues had different accessibilities, and the labeled loops themselves showed variable extents of quenching and rates of motion during ligand binding. The vestibular loops closed around FeEnt in about a second, in the order L3 > L11 > L7 > L2 > L5 > L8 > L4. This sequence suggested that the loops bind the metal complex like the fingers of two hands closing on an object, by individually adsorbing to the iron chelate. Fluorescence from L3 followed a biphasic exponential decay as FeEnt bound, but fluorescence from all the other loops followed single exponential decay processes. After binding, the restoration of fluorescence intensity (from any of the labeled loops) mirrored cellular uptake that depleted FeEnt from solution. Fluorescence microscopic images also showed FeEnt transport, and demonstrated that ferric siderophore uptake uniformly occurs throughout outer membrane, including at the poles of the cells, despite the fact that TonB, its inner membrane transport partner, was not detectable at the poles.

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Li, Juan, Jian Long, and Fu Xing Kang. "Fluorescence Titration of Loosely Bound Extracellular Polymeric Substances with Cu (II) from Hongfeng Lake Sediment." Advanced Materials Research 610-613 (December 2012): 280–83. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.280.

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In order to understand the micro-interfacial relationship between environmental copper ions and loosely bound extracellular polymeric substances (LB-EPS), a fluorescence titration of LB-EPS from the Hongfeng lake sediment by Cu (Ⅱ) was studied. Results showed that Cu (Ⅱ) could debase the fluorescence intensity (FI) of LB-EPS. Titration of LB-EPS by Cu (Ⅱ) at pH values of 4.0, 6.0, 7.0 and 9.0 demonstrated an obvious variety of wavelength spectra. The FI of LB-EPS reacting with Cu (Ⅱ) (2.5×10-4M), with the increase of pH values, decreased, which was attributed to more conjunct capacity of the fluorophore with Cu (Ⅱ) in alkaline conditions. At low or middle pH, the quenching of LB-EPS by Cu (Ⅱ) was attributed to the complex quenching triggered by ligand processes; and in the high pH the cause of quenching was not only linked to complex quenching, but also related to collision quenching.

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Zhang, Zhi, Xiao Jun Hu, Jing Feng, and Li Bin Niu. "A New Type of Self-Assembled Fluorescent Chemosensor." Advanced Materials Research 800 (September 2013): 27–30. http://dx.doi.org/10.4028/www.scientific.net/amr.800.27.

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According to the principle of dynamic quenching a new ON-OFF fluorescent chemosensor for Cu2+ ions was designed, this chemosensor was composed of sodium dodecyl benzene sulfonate (SDBS), p-tert-butylthiacalix[4]arene (TCA) and perylene through the form of self-assembly in aqueous solution. Addition of Cu2+ ions could result in a quenching of the fluorescence emission of perylene inside micelles, which is ascribed to intramicellar complex-fluorophore electron-transfer or energy-transfer effects induced by the complexation of TCA with the Cu2+ ions.The results of the experiment indicated that: With the condition of TCA/perylene = 1000/1, SDBS concentration was 50mmol/L and pH value above 7, concentration of Cu2+ ion can be linearly determined according to the fluorescence quenching in a certain range.

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Hu, Xiao Jun, Xin Yan Hu, and Zhi Zhang. "A New Approach to Fluorescent Chemosensor of Cu²⁺ Ion." Applied Mechanics and Materials 513-517 (February 2014): 65–69. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.65.

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According to the principle of dynamic quenching a new ON-OFF fluorescent chemosensor for Cu2+ions was designed, this chemosensor was composed of p-tert-butylthiacalix [arene (TCA),sodium dodecyl sulfate (SDS) and perylene through the form of self-assembly in aqueous solution. Addition of Cu2+ions could result in a quenching of the fluorescence emission of perylene inside micelles, which due to intramicellar complex-fluorophore electron-transfer or energy-transfer effects induced by the complexation of TCA with the Cu2+ions.The experimental results indicated that: Under the condition of TCA/perylene was 800/1, SDS concentration was 150mmol/L and pH value above 9, according to the fluorescence quenching ,within a certain range of the concentration of Cu2+ion can be linearly determined.

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Walhorn, Volker, Jan Paskarbeit, Heinrich Gotthard Frey, Alexander Harder, and Dario Anselmetti. "Distance dependence of near-field fluorescence enhancement and quenching of single quantum dots." Beilstein Journal of Nanotechnology 2 (September 29, 2011): 645–52. http://dx.doi.org/10.3762/bjnano.2.68.

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In fluorescence microscopy and spectroscopy, energy transfer processes between single fluorophores and fluorophore quencher pairs play an important role in the investigation of molecular distances or orientations. At distances larger than about 3 nm these effects originate predominantly from dipolar coupling. As these experiments are commonly performed in homogenous media, effects at the interface boundaries can be neglected. Nevertheless, the combination of such assays with single-molecule manipulation techniques such as atomic force microscopy (AFM) requires a detailed understanding of the influence of interfaces on dipolar coupling effects. In the presented work we used a combined total internal reflection fluorescence microscopy (TIRFM)–AFM setup to elucidate this issue. We measured the fluorescence emission emanating from single quantum dots as a function of distance from the apex of a gold-coated cantilever tip. As well as fluorescence quenching at close proximity to the tip, we found a nonlinear and nonmonotonic distance dependence of the fluorescence emission. To confirm and interpret our findings we performed calculations on the basis of a simplified multiple multipole (MMP) approach, which successfully supports our experimental data. Moreover, we revealed and quantified the influence of interfering processes such as field enhancement confined at interface boundaries, mirror dipoles and (resonant) dipolar coupling.

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Ewing, Heather, Virneliz Fernández-Vega, Timothy P. Spicer, Peter Chase, Steven Brown, Louis Scampavia, William R. Roush, et al. "Fluorometric High-Throughput Screening Assay for Secreted Phospholipases A2 Using Phospholipid Vesicles." Journal of Biomolecular Screening 21, no. 7 (July 10, 2016): 713–21. http://dx.doi.org/10.1177/1087057116646742.

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There is interest in developing inhibitors of human group III secreted phospholipase A2 (hGIII-sPLA2) because this enzyme plays a role in mast cell maturation. There are no potent inhibitors for hGIII-sPLA2 reported to date, so we adapted a fluorescence-based enzyme activity monitoring method to a high-throughput screening format. We opted to use an assay based on phospholipid substrate present in phospholipid vesicles since this matrix more closely resembles the natural substrate of hGIII-sPLA2, as opposed to phospholipid/detergent mixed micelles. The substrate is a phospholipid analogue containing BODIPY fluorophores dispersed as a minor component in vesicles of nonfluorescent phospholipids. Action of hGIII-sPLA2 liberates a free fatty acid from the phospholipid, leading to a reduction in quenching of the fluorophore and hence an increase in fluorescence. The assay uses optical detection in a 1536-well plate format with an excitation wavelength far away from the UV range so as to minimize false-positive library hits that result from quenching of the fluorescence. The high-throughput screen was successfully carried out on a library of 370,276 small molecules. Several hits were discovered, and data have been uploaded to PubChem. This study describes the first high-throughput optical screening assay for secreted phospholipase A2 inhibitors based on a phospholipid vesicle substrate.

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Moyon, N. Shaemningwar, and Sivaprasad Mitra. "Luminol Fluorescence Quenching in Biomimicking Environments: Sequestration of Fluorophore in Hydrophobic Domain." Journal of Physical Chemistry B 115, no. 33 (August 25, 2011): 10163–72. http://dx.doi.org/10.1021/jp204424w.

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Goncharenko, N. A., O. P. Dmytrenko, O. L. Pavlenko, M. P. Kulish, I. P. Pundyk, A. I. Lesyuk, T. O. Busko, et al. "Complexation Peculiarities in “Doxorubicin–Bovine Serum Albumin–Gold Nanoparticles” Heterosystem. The Fluo-rescence Study." Ukrainian Journal of Physics 65, no. 6 (June 9, 2020): 468. http://dx.doi.org/10.15407/ujpe65.6.468.

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The fluorescence (FL) quenching in aqueous solutions of doxorubicin (DOX)–bovine serum albumin (BSA)–gold nanoparticles (AuNPs) is studied. The existence of additional mechanisms of DOX-BSA complex formation leading to an increase in the binding constant K and a decrease in the number of binding sites n and the distance between the fluorophore and energy acceptors due to the presence of gold nanoparticles is shown.

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37

Cinquetti, Raffaella, Francesca Guia Imperiali, Salvatore Bozzaro, Daniele Zanella, Francesca Vacca, Cristina Roseti, Barbara Peracino, Michela Castagna, and Elena Bossi. "Characterization of Transport Activity of SLC11 Transporters in Xenopus laevis Oocytes by Fluorophore Quenching." SLAS DISCOVERY: Advancing the Science of Drug Discovery 26, no. 6 (April 7, 2021): 798–810. http://dx.doi.org/10.1177/24725552211004123.

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Membrane proteins are involved in different physiological functions and are the target of pharmaceutical and abuse drugs. Xenopus laevis oocytes provide a powerful heterologous expression system for functional studies of these proteins. Typical experiments investigate transport using electrophysiology and radiolabeled uptake. A two-electrode voltage clamp is suitable only for electrogenic proteins, and uptake measurements require the existence of radiolabeled substrates and adequate laboratory facilities. Recently, Dictyostelium discoideum Nramp1 and NrampB were characterized using multidisciplinary approaches. NrampB showed no measurable electrogenic activity, and it was investigated in Xenopus oocytes by acquiring confocal images of the quenching of injected fluorophore calcein. This method is adequate to measure the variation in emitted fluorescence, and thus transporter activity indirectly, but requires long experimental procedures to collect statistically consistent data. Considering that optimal expression of heterologous proteins lasts for 48–72 h, a slow acquiring process requires the use of more than one batch of oocytes to complete the experiments. Here, a novel approach to measure substrate uptake is reported. Upon injection of a fluorophore, oocytes were incubated with the substrate and the transport activity measured, evaluating fluorescence quenching in a microplate reader. The technique permits the testing of tens of oocytes in different experimental conditions simultaneously, and thus the collection of significant statistical data for each batch, saving time and animals. The method was tested with different metal transporters (SLC11), DMT1, DdNramp1, and DdNrampB, and verified with the peptide transporter PepT1 (SLC15). Comparison with traditional methods (uptake, two-electrode voltage clamp) and with quenching images acquired by fluorescence microscopy confirmed its efficacy.

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38

Zammit, Ramon, Maria Pappova, Esther Zammit, John Gabarretta, and David C. Magri. "1,3,5-Triarylpyrazolines — pH-driven off-on-off molecular logic devices based on a “receptor1-fluorophore-spacer-receptor2” format with internal charge transfer (ICT) and photoinduced electron transfer (PET) mechanisms." Canadian Journal of Chemistry 93, no. 2 (February 2015): 199–206. http://dx.doi.org/10.1139/cjc-2014-0266.

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The excited state photophysical properties of the 1,3,5-triarylpyrazolines 1–4 were studied in methanol and 1:1 (v/v) methanol–water, as well as 1:4 (v/v) methanol–water and water by fluorescence spectroscopy. The molecules 2–4 incorporate a “receptor1-fluorophore-spacer-receptor2” format while 1 is a reference compound based on a “fluorophore-receptor1” design. The molecular probes operate according to photoinduced electron transfer (PET) and internal charge transfer (ICT) processes. At basic and neutral pHs, 2–4 are essentially nonfluorescent due to PET from the electron-donating dimethylamino moiety appended on the 5-phenyl ring to the excited state of the 1,3,5-triarylpyrazoline fluorophore. At proton concentrations of 10−3 mol/L, the dimethylamino unit is protonated resulting in a strong blue fluorescence about 460 nm with significant quantum yields up to 0.54. At acid concentrations above 10−2 mol/L, fluorescence quenching is observed by an ICT mechanism due to protonation of the pyrazoline chromophore. Symmetrical off-on-off fluorescence–pH profiles are observed, spanning six log units with a narrow on window within three pH units. Hence, 2–4 are novel examples of ternary photonic pH sensing molecular devices.

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Nomura, Wataru, Nami Ohashi, Yoshiaki Okuda, Tetsuo Narumi, Teikichi Ikura, Nobutoshi Ito, and Hirokazu Tamamura. "Fluorescence-Quenching Screening of Protein Kinase C Ligands with an Environmentally Sensitive Fluorophore." Bioconjugate Chemistry 22, no. 5 (May 18, 2011): 923–30. http://dx.doi.org/10.1021/bc100567k.

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Acuna, Guillermo P., Martina Bucher, Ingo H. Stein, Christian Steinhauer, Anton Kuzyk, Phil Holzmeister, Robert Schreiber, et al. "Distance Dependence of Single-Fluorophore Quenching by Gold Nanoparticles Studied on DNA Origami." ACS Nano 6, no. 4 (March 30, 2012): 3189–95. http://dx.doi.org/10.1021/nn2050483.

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41

Yang, Darwin, Rebecca L. Pinals, Alison Lui, and Markita P. Landry. "Monitoring Corona Exchange Dynamics on Single-Walled Carbon Nanotubes Using Multiplexed Fluorophore Quenching." ECS Meeting Abstracts MA2020-01, no. 35 (May 1, 2020): 2478. http://dx.doi.org/10.1149/ma2020-01352478mtgabs.

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42

Sunbul, Murat, and Andres Jäschke. "Contact-Mediated Quenching for RNA Imaging in Bacteria with a Fluorophore-Binding Aptamer." Angewandte Chemie International Edition 52, no. 50 (October 16, 2013): 13401–4. http://dx.doi.org/10.1002/anie.201306622.

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43

Sunbul, Murat, and Andres Jäschke. "Contact-Mediated Quenching for RNA Imaging in Bacteria with a Fluorophore-Binding Aptamer." Angewandte Chemie 125, no. 50 (October 16, 2013): 13643–46. http://dx.doi.org/10.1002/ange.201306622.

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44

Aliaga, Carolina, Patricio Fuentealba, Marcos Caroli Rezende, and Carlos Cárdenas. "Mechanism of fluorophore quenching in a pre-fluorescent nitroxide probe: A theoretical illustration." Chemical Physics Letters 593 (February 2014): 89–92. http://dx.doi.org/10.1016/j.cplett.2013.12.059.

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45

Kazemi, Sayed Yahya. "Quenching effect of l-tyrosine on peroxyoxalate chemiluminescence of berberine as the fluorophore." Journal of the Iranian Chemical Society 10, no. 5 (February 15, 2013): 915–20. http://dx.doi.org/10.1007/s13738-013-0228-2.

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46

Möller, Friederike M., Phil Holzmeister, Tapasi Sen, Guillermo P. Acuna, and Philip Tinnefeld. "Angular modulation of single-molecule fluorescence by gold nanoparticles on DNA origami templates." Nanophotonics 2, no. 3 (July 1, 2013): 167–72. http://dx.doi.org/10.1515/nanoph-2013-0011.

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AbstractWe study the angular fluorescence intensity modulation of a single dye positioned near a spherical gold nanoparticle, induced by rotation of linearly polarized excitation light. Accurate positioning and alignment of nanoparticle and fluorophore with respect to each other and the incoming electric field is achieved by a three-dimensional, self-assembled DNA origami. An intensity map is obtained for a fixed distance and two different nanoparticle diameters, revealing polarization-dependent enhancement and quenching of fluorescence intensity in good agreement to numerical simulations.

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47

Thomas, K. George, Binil Itty Ipe, and P. K. Sudeep. "Photochemistry of chromophore-functionalized gold nanoparticles." Pure and Applied Chemistry 74, no. 9 (January 1, 2002): 1731–38. http://dx.doi.org/10.1351/pac200274091731.

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It is generally believed that metal nanoparticles strongly quench the singlet-excited states of chromophores when attached to nanoparticle surfaces, through an energy-transfer mechanism, which limits their application in optoelectronic devices and photonic materials. Recent studies of fluorophore-linked metal nanoparticles reveal that there is a dramatic suppression in the quenching of the singlet-excited state of these molecules and they possess unusual photophysical properties. A summary of our work on the photophysical and excited-state properties of chromophore-functionalized gold nanoparticles is presented in this article. Pyrene-capped gold nanoparticles showed normal fluorescence in nonpolar solvents and an intermolecular excimer formation at higher loadings. The quenching of the emission, observed in pyrene-labeled gold nanoparticles in polar solvents, is attributed to the formation of pyrene radical cation through a photoinduced electron-transfer process. We have also functionalized gold nanoparticles using a thiol derivative of fullerene. The quenching of fluorescence and decreased yields of triplet-excited state, observed in these systems, are attributed to an energy-transfer process.

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Essawy, Amr A., and Hazim M. Ali. "Novel spectrofluorimetric assessment of ondansetron hydrochloride based on excited state quenching of pararosaniline fluorophore." Journal of the Taiwan Institute of Chemical Engineers 91 (October 2018): 634–42. http://dx.doi.org/10.1016/j.jtice.2018.06.024.

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49

Chen, Pei Yuan, D. Pearce, and Alan S. Verkman. "Membrane water and solute permeability determined quantitatively by self-quenching of an entrapped fluorophore." Biochemistry 27, no. 15 (July 1988): 5713–18. http://dx.doi.org/10.1021/bi00415a048.

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Pulido, C., and Ó. Esteban. "Tapered polymer optical fiber oxygen sensor based on fluorescence-quenching of an embedded fluorophore." Sensors and Actuators B: Chemical 184 (July 2013): 64–69. http://dx.doi.org/10.1016/j.snb.2013.04.061.

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