Simultaneous analysis of multiple fluorescence decay curves: A global approach

Knutson, Jay R.; Beechem, Joseph M.; Brand, Ludwig

doi:10.1016/0009-2614(83)87454-5

Cited by 594 publications

(363 citation statements)

References 18 publications

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“…This advantage can be derived if multiple fluorescence decay curves, acquired under different conditions, are simultaneously analyzed. This is known as the global analysis in which the simultaneous analyses of multiple decay curves are carried out in terms of internally consistent sets of fitting parameters (Knutson et al, 1983;Beechem, 1989Beechem, , 1992Beechem et al, 1991). Global analysis thus turns out to be very useful for the prediction of the manner in which the parameters recovered from a set of separate fluorescence decays vary as a function of an independent variable and helps distinguish between models proposed to describe a system.…”

Section: Methodsmentioning

confidence: 99%

Membrane Organization at Low Cholesterol Concentrations: A Study Using 7-Nitrobenz-2-oxa-1,3-diazol-4-yl-Labeled Cholesterol

1996

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Cholesterol is most often found distributed nonrandomly in the plane of the bilayer, giving rise to cholesterol-rich and -poor domains. Many of these domains are thought to be crucial for the maintenance of membrane structure and function. However, such well-characterized domains generally occur in the membranes that contain relatively large amounts of cholesterol. Cholesterol organization in membranes containing very low amounts of cholesterol has not been investigated extensively. Recent evidence from differential-scanning calorimetric studies suggests that cholesterol may not form uniform monodisperse solutions, as assumed earlier, in the membranes even at very low concentrations. Fluorescent cholesterol analogues, when chosen carefully, offer a powerful approach for studying the distribution and organization of cholesterol in membranes at low concentrations. In this paper, we have studied the organization of cholesterol in membranes at very low concentrations (up to 5 mol % of the total lipid) using a fluorescent cholesterol analogue (NBD-cholesterol) which is labeled with the 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) group at the flexible acyl chain, without any alteration in the structural features necessary for proper membrane incorporation. Our results show that NBD-cholesterol exhibits local organization even at very low concentrations. This is consistent with the recently suggested model of cholesterol organization in membranes at low concentrations, involving the formation of transbilayer, tail-to-tail dimers The fluid mosaic model for biological membranes defines the membrane as an oriented, two-dimensional, viscous solution of proteins and lipids in instantaneous thermodynamic equilibrium (Singer & Nicolson, 1972). Although the basic tenets of this model have stood the test of time, one of its implicit assumptions, that the lipid molecules merely provide the milieu for the membrane proteins and that they are distributed uniformly throughout the bilayer, has been found to be not quite true. In fact, current evidence points out that both transverse and lateral regionalization, which can be described in terms of micro-and macrodomains, are common features of many biological membranes (Curtain et al., 1988;Edidin, 1992;Tocanne, 1992;Glaser, 1993;Jacobson et al., 1995).Cholesterol is one of the membrane components that is found, more often than not, distributed nonrandomly in structural and kinetic domains or pools in both biological and model membranes (Yeagle, 1985;Gennis, 1989;Schroeder et al., 1991;Liscum & Underwood, 1995). The reason for this lies in the rather unusual chemical structure of cholesterol that can by no means be considered a representative component of the "bulk" membrane (see Figure 1). The unusual shape of cholesterol also causes a phase separation in membranes at relatively high concentrations, resulting in the formation of cholesterol-rich and -poor domains that are structurally and compositionally so distinct that they can be observed histochemically and isolated physical...

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Section: Methodsmentioning

confidence: 99%

Membrane Organization at Low Cholesterol Concentrations: A Study Using 7-Nitrobenz-2-oxa-1,3-diazol-4-yl-Labeled Cholesterol

1996

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“…[21][22] Advanced procedures in data treatment, such as the global analysis method of the fluorescence anisotropy decay surface, have allowed the study of the rotation relaxation dynamics of fluorescent molecules in isotropic solvents and in nonhomogeneous media. 23,24 The photophysical properties of thionine and phenosafranine dyes covalently bound to poly(acrylamidoglycol acid) and poly(methyloacrylamide) were investigated using stationary and TRFS measurements. 25 Although there are several reports of fluorescence anisotropy studies of aromatic probes in the presence of polymers, the rotational relaxation of a dye free in solution, and chemically bound to a macromolecule, has not yet been compared.…”

Section: Introductionmentioning

confidence: 99%

Time resolved fluorescence anisotropy of basic dyes bound to poly(methacrylic acid) in solution

Oliveira¹,

Gehlen²

2003

J. Braz. Chem. Soc.

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Soluções de poli(ácido metacrílico) atático, PAMA com peso molecular na faixa de (1,6 a 3,4) x 10 5 g mol -1 , e com corantes fluorescentes 9-aminoacridina ou azul do nilo ligados à cadeia, foram estudados por medidas fotofísicas em função da viscosidade e polaridade do solvente. O comportamento dos segmentos da cadeia do PAMA nas vizinhanças da sonda fluorescente foi descrito pela mudança na rotação difusional dos corantes. O etilenoglicol expande a cadeia polimérica quando comparada com a forma mais compactada do corante-PAMA em 50% água/etilenoglicol. A variação do tempo de relaxação rotacional do corante ligado ao PAMA indica uma expansão progressiva da cadeia polimérica para uma forma aberta em etilenoglicol.Solutions of atactic poly(methacrylic acid), PMAA, with molecular weights in the range of (1.6 to 3.4) x 10 5 g mol -1 , and labeled with the fluorescent dyes 9-aminoacridine or Nile blue were studied by photophysical measurements as a function of solvent viscosity and polarity. The conformational behavior of the PMAA chain segments around the fluorescent probe was reported by the change in the rotational diffusion of the dyes. Ethylene glycol swells the polymer chain compared with the more contracted conformation of PMAA in 50% water/ethylene glycol. The change in the rotational relaxation time of the dye bound to PMAA with the decrease of water content in the solvent mixture indicates a progressive expansion of polymer chain to a more open coil form in solution.Keywords: dyes, polyelectrolytes, PMAA, rotational diffusion, solvent friction IntroductionPhotophysical studies of polymers in solution have been extensively reported in recent years. 1,2 Time resolved fluorescence spectroscopy (TRFS) was found to be particularly useful in the study of several types of polymers in solution, and in the presence of additives. 3-10 Time resolved anisotropy decay of a fluorescent probe attached to a polymer chain reflects the rotational relaxation of the probe, and the local dynamics of the polymer segments in solution. 2 The dependence of the segmental dynamics as a function solvent viscosity was studied by TRFS using anthracene attached to 1,2 polybutadiene. 11,12 The polymer local dynamics as well as the structural properties and relaxation processes of polymer and blends were studied by steady state and dynamic fluorescence using anthranyl and pyrenyl groups. [13][14][15] Fluorescence studies of polymethacrylic acid (PMAA) and polyacrylic acid (PAA) containing aromatic fluorescent probes such as naphthalene, anthracene and pyrene have been carried out by many authors to elucidate the properties of those polyelectrolytes in different solvents, pH, and surfactant addition. [16][17][18][19][20] Fluorescence anisotropy reflects the microviscosity and the solubilization dynamics of the probe molecule in solutions of polyelectrolytes. Reports in the literature using polarization and anisotropy of rhodamine 6 G in ethylene glycol demonstrate that the depolarization properties of the probe have relations with the solv...

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“…[14][15][16][17] The PL decays at all emission wavenumbers within 535-560 nm were used. The method provides besides the exponential time constants of decay, the decay amplitude spectra ͑DAS͒.…”

Section: -2mentioning

confidence: 99%

“…To determine and characterize the number, time constants, and amplitude spectra decay from the exponential data, we used both exponential fitting by global nonlinear least-squares [14][15][16][17] and lifetime distribution recovery by the maximum entropy and Monte Carlo method. [18][19][20][21][22] From the comparison between the terbium PL properties in the nonsilylated and silylated USY zeolites, the effects of the silylation were also inferred.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence study of terbium-exchanged ultrastable Y zeolites: Number of species, photoluminescence decays, and decay-associated spectra

Tiseanu¹,

Lórenz-Fonfrı́a²,

Pârvulescu³

et al. 2008

Journal of Applied Physics

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Terbium-exchanged ultrastable Y ͑USY͒ zeolites were investigated by using time-resolved photoluminescence spectroscopy techniques and methods. To determine the distribution of terbium species in USY zeolites together with their photoluminescence properties, several analysis methods for the time-resolved luminescence spectra were used such as the area normalization of time-resolved photoluminescence spectra, singular value decomposition, global nonlinear least squares, and the maximum entropy. Except for a questionable long lifetime, small contribution of a terbium species with lifetime of 1.9-2.1 ms, all the experimental and analysis results converged to a two terbium species distribution with lifetimes varying between 410-440 and 1000-1100 s. The effects of the silylation of terbium-exchanged USY zeolites with phenyl-, vinyl-, and hexadecyltrimethoxysilanes on the lanthanide's photoluminescence properties were also described.

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Simultaneous analysis of multiple fluorescence decay curves: A global approach

Cited by 594 publications

References 18 publications

Membrane Organization at Low Cholesterol Concentrations: A Study Using 7-Nitrobenz-2-oxa-1,3-diazol-4-yl-Labeled Cholesterol

Membrane Organization at Low Cholesterol Concentrations: A Study Using 7-Nitrobenz-2-oxa-1,3-diazol-4-yl-Labeled Cholesterol

Time resolved fluorescence anisotropy of basic dyes bound to poly(methacrylic acid) in solution

Photoluminescence study of terbium-exchanged ultrastable Y zeolites: Number of species, photoluminescence decays, and decay-associated spectra

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