Effects of solvent polarity and solvent viscosity on the fluorescent properties of molecular rotors and related probes

Haidekker, Mark A.; Brady, Thomas P.; Lichlyter, Darcy; Theodorakis, Emmanuel A.

doi:10.1016/j.bioorg.2005.07.005

Cited by 360 publications

(329 citation statements)

References 38 publications

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“…When anle138b is dissolved in solvents, which are less polar than water or have a higher viscosity, one finds larger amplitudes of the fluorescence emission and a changed emission spectrum. For toluene (which has the smallest polarity, dielectric constant DC = 2.39 and a viscosity η = 0.59 mPa s [26]), we find the peak around 335 nm. In the more viscous glycerol-water mixture (DC ≈ 50.6 and η ≈ 45.9 mPa s at 25°C [27,28]) the peak is red-shifted by ca.…”

Section: Absorption and Emission Propertiesmentioning

confidence: 78%

Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates

Deeg

Reiner

Schmidt

et al. 2015

Biochimica et Biophysica Acta (BBA) - General Subjects

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Background: Special diphenyl-pyrazole compounds and in particular anle138b were found to reduce the progression of prion and Parkinson's disease in animal models. The therapeutic impact of these compounds was attributed to the modulation of α-synuclein and prion-protein aggregation related to these diseases. Methods: Photophysical and photochemical properties of the diphenyl-pyrazole compounds anle138b, anle186b and sery313b and their interaction with monomeric and aggregated α-synuclein were studied by fluorescence techniques. Results: The fluorescence emission of diphenyl-pyrazole is strongly increased upon incubation with α-synuclein fibrils, while no change in fluorescence emission is found when brought in contact with monomeric α-synuclein. This points to a distinct interaction between diphenyl-pyrazole and the fibrillar structure with a high binding affinity (K d = 190 ± 120 nM) for anle138b. Several α-synuclein proteins form a hydrophobic binding pocket for the diphenyl-pyrazole compound. A UV-induced dehalogenation reaction was observed for anle138b which is modulated by the hydrophobic environment of the fibrils. Conclusion: Fluorescence of the investigated diphenyl-pyrazole compounds strongly increases upon binding to fibrillar α-synuclein structures. Binding at high affinity occurs to hydrophobic pockets in the fibrils. General significance: The observed particular fluorescence properties of the diphenyl-pyrazole molecules open new possibilities for the investigation of the mode of action of these compounds in neurodegenerative diseases. The high binding affinity to aggregates and the strong increase in fluorescence upon binding make the compounds promising fluorescence markers for the analysis of aggregation-dependent epitopes.

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Section: Absorption and Emission Propertiesmentioning

confidence: 78%

Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates

Deeg

Reiner

Schmidt

et al. 2015

Biochimica et Biophysica Acta (BBA) - General Subjects

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“…Strong polarity-dependent Stokes's shifts are observed in many coumarin derivatives [11][12][13][14][15][16]. The 7-NEt2 coumarin dyes are seen to exhibit quite unusual behavior in certain nonpolar solvents.…”

Section: Introductionmentioning

confidence: 98%

Study of solvent effect in laser emission from Coumarin 540 dye solution

et al. 2007

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The results of a brief investigation of the amplified spontaneous emission and lasing characteristics of Coumarin 540 dye in as many as ten different solvents are reported. It has been found that C 540 dye solutions contained within a rectangular quartz cuvette give laser emission with well resolved equally spaced modes when pumped with a 476 nm beam. The modes were found to originate from the subcavities formed by the plane-parallel walls of the cuvette containing the high-gain medium. While the quantum yield remains a decisive factor, a clear correlation between the total width of the emission spectra and the refractive indices of the solvents of the respective samples has been demonstrated. The well-resolved mode structure exhibited by the emission spectra gives clear evidence of the lasing action taking place in the gain medium, and the number of modes enables us to compare the gain of the media in different samples. A detailed discussion of the solvent effect in the lasing characteristics of C540 in different solutions is given.

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“…5,9 Increased glycerol content is known to increase viscosity with only minimal changes of solvent polarity. 10 Glycerol contents of 40, 50, 60, 70, and 80% resulted in viscosities of 72, 109, 165, 248, and 374 mPa‚s, respectively. As shown in Figure 3, both the direct rotor emission and the rotor emission through RET excitation exhibit viscosity sensitivity.…”

mentioning

confidence: 97%

A Ratiometric Fluorescent Viscosity Sensor

et al. 2005

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Variations in fluid viscosity are linked to a variety of functions and diseases both at the cellular level (e.g., membrane and cytoplasmic viscosity changes in cell signaling modulation) 1 and at the organismal level (e.g., blood, plasma, or lymphatic fluid viscosity changes in diabetes, hypertension, infarction, and aging). 2 It has been proposed that monitoring of biofluid viscosity could provide a diagnostic tool for the detection of diseases. 3 Since mechanical devices do not provide the spatial and temporal resolution needed, a new type of fluorescent-based viscosity sensors was developed. 4 These sensors are based on a class of environmentsensitive fluorescent dyes that are characterized by a viscositydependent emission quantum yield. 4,5 The chemical structure of these dyes contains an electron donor unit (such as a nitrogen atom) in conjugation with an electron acceptor unit (such as a nitrile). Upon photoexcitation, the two units can rotate relative to each other in a manner that is dependent on the viscosity of their environment. Representative examples of such fluorescent rotors are 9-(dicyanoVinyl)julolidine (DCVJ, 1) and 2-cyano-3-(4-dimethylaminophenyl)acrylic acid methyl ester (CMAM, 2) ( Figure 1). 5 Their viscosity-dependent fluorescent quantum yield is described by the Förster-Hoffmann equation (eq 1). 6 Fluorescent molecular rotors have been used for viscosity studies that are performed by steady-state fluorescence through emission intensity measurements. This method suffers, however, from drawbacks arising from changes of the fluid optical properties and fluctuations in dye concentrations. An additional disadvantage is that a calibration curve is needed for the absolute determination of viscosity. 5 As a consequence, changes in fluid properties and dye concentration may cause erroneous readings.We hypothesized that a dual dye composed of two distinct fluorescent units, one providing an internal intensity reference and the other acting as a viscosity sensor, would create a ratiometric sensing system, thus overcoming the above disadvantages. Dividing the sensor emission intensity by the reference emission intensity would yield a normalized intensity that should not only eliminate some of the fluid-and concentration-related artifacts but also provide a means to quantify viscosity by an internal reference. To test this hypothesis, we synthesized a compound 4 in which the CMAM motif was coupled with 7-methoxycoumarin-3-carboxylic acid (MCCA, 3). We chose MCCA as the donor fluorophore in order to induce excitation of the rotor moiety (CMAM) via Resonance Energy Transfer (RET). 7 We envisioned that, due to its viscosity-independent quantum yield, MCCA could be used as both the internal reference and the RET donor. The latter event could then excite the CMAM motif, resulting in a viscosity-dependent emission of the rotor. The linker was chosen to maintain a distance between the chromophores in the same range as the Förster distance 7a to allow considerable energy transfer to the acceptor combined w...

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Effects of solvent polarity and solvent viscosity on the fluorescent properties of molecular rotors and related probes

Cited by 360 publications

References 38 publications

Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates

Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates

Study of solvent effect in laser emission from Coumarin 540 dye solution

A Ratiometric Fluorescent Viscosity Sensor

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