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Kitchner E, Seung M, Chavez JL, Ceresa L, Kimball J, Gryczynski I, Gryczynski Z. Fluorescence measurements: importance of G-factor correction, magic angle, and observation wavelengths. Methods Appl Fluoresc 2022; 10. [DOI: 10.1088/2050-6120/ac92c5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 09/16/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Excitation and emission (observation) conditions heavily impact fluorescence measurements. Both observed spectra and intensity decays (fluorescence lifetimes), when incorrectly measured, may lead to incorrect data interpretations. In this report, we discuss the role of observation conditions in steady-state and time-resolved (lifetime) fluorescence measurements. We demonstrate the importance of the correction for uneven transmissions of vertical and horizontal polarizations of emission light through the detection system. The necessity of using so-called total fluorescence intensity or intensity measured under magic angle (MA) conditions has been demonstrated for both steady-state and time-resolved fluorescence measurements. The dependence of lifetime measurements on observation (emission) wavelengths is also discussed. Two fluorophores, rhodamine 6G (R6G) and 4,4 Dimethylamino-cyano stilbene (DCS) in two solvents - ethanol and glycerol have been used in order to cover a broad range of dye polarities and solvent viscosities.
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Kristoffersen AS, Erga SR, Hamre B, Frette Ø. Testing fluorescence lifetime standards using two-photon excitation and time-domain instrumentation: rhodamine B, coumarin 6 and lucifer yellow. J Fluoresc 2014; 24:1015-24. [PMID: 24866152 PMCID: PMC4070492 DOI: 10.1007/s10895-014-1368-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 02/24/2014] [Indexed: 11/25/2022]
Abstract
Having good information about fluorescence lifetime standards is essential for anyone performing lifetime experiments. Using lifetime standards in fluorescence spectroscopy is often regarded as a straightforward process, however, many earlier reports are limited in terms of lifetime concentration dependency, solvents and other technical aspects. We have investigated the suitability of the fluorescent dyes rhodamine B, coumarin 6, and lucifer yellow as lifetime standards, especially to be used with two-photon excitation measurements in the time-domain. We measured absorption and emission spectra for the fluorophores to determine which wavelengths we should use for the excitation and an appropriate detector range. We also measured lifetimes for different concentrations, ranging from 10(-2)- 10(-6) M, in both water, ethanol and methanol solutions. We observed that rhodamine B lifetimes depend strongly on concentration. Coumarin 6 provided the most stable lifetimes, with a negligible dependency on concentration and solvent. Lucifer yellow lifetimes were also found to depend little with concentration. Finally, we found that a mix of two fluorophores (rhodamine B/coumarin 6, rhodamine B/lucifer yellow, and coumarin 6/lucifer yellow) all yielded very similar lifetimes from a double-exponential decay as the separate lifetimes measured from a single-exponential decay. All lifetime measurements were made using two-photon excitation and obtaining lifetime data in the time-domain using time-correlated single-photon counting.
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Affiliation(s)
- Arne S Kristoffersen
- Department of Physics and Technology, University of Bergen, P. O. Box 7803, N-5020, Bergen, Norway,
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Tian Z, Lis L, Kass SR. Carbon–Hydrogen Bond Dissociation Energies: The Curious Case of Cyclopropene. J Org Chem 2013; 78:12650-3. [DOI: 10.1021/jo402263v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhixin Tian
- Department
of Chemistry, Tongji University, Shanghai 200092, China
| | - Lev Lis
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Steven R. Kass
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Borowiak M, Grobelna B, Synak A, Bojarski P, Kubicki AA. Time-resolved emission spectra of 4-dimethylamino-4'-cyano-stilbene and resveratrol in high viscosity solvents and silica matrices. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 115:111-117. [PMID: 23832219 DOI: 10.1016/j.saa.2013.06.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 04/24/2013] [Accepted: 06/08/2013] [Indexed: 06/02/2023]
Abstract
Time-resolved emission spectra of 4-dimethylamino-4'-cyano-stilbene (DMACS) and 3,5,4'-trihydroxy-stilbene (resveratrol, RSV) in propylene glycol and in rigid silica xerogel matrix at 23°C were studied. For the polar molecule DMACS in propylene glycol, a 66nm shift of maximum wavelength of emission spectra was observed within 1ns after excitation, and most of the shift occurred during the first 200ps. For resveratrol in propylene glycol no such a shift was observed. The rigid silica environment eliminates some deactivation pathways and stabilizes spectroscopic properties of both molecules. Spectral properties of nonpolar and high dipole moment molecules in viscous liquids and rigid environments are compared. Results are explained on the basis of intramolecular processes and solute-solvent relaxation, as well.
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Affiliation(s)
- Małgorzata Borowiak
- University of Gdańsk, Institute of Experimental Physics, Molecular Spectroscopy Division, 80-952 Gdańsk, Wita Stwosza 57, Poland
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Luchowski R, Sabnis S, Szabelski M, Sarkar P, Raut S, Gryczynski Z, Borejdo J, Bojarski P, Gryczynski I. Self-quenching of uranin: Instrument response function for color sensitive photo-detectors. JOURNAL OF LUMINESCENCE 2010; 130:2446-2451. [PMID: 21331290 PMCID: PMC3049910 DOI: 10.1016/j.jlumin.2010.07.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Concentration is a key determining factor in the fluorescence properties of organic fluorophores. We studied self-quenching of disodium fluorescein (uranin) fluorescence in polyvinyl alcohol (PVA) thin films. The concentration dependent changes in brightness and anisotropy were followed by a lifetime decrease. We found that at a concentration of 0.54 M, the lifetime decreases to 7 ps. At a concentration of 0.18 M the lifetime was 10 ps with the relatively high quantum yield of 0.002. In these conditions the fluorescence intensity decay was homogeneous (well approximated by a single lifetime). We realized that such a sample was an ideal fluorescence lifetime standard for spectroscopy and microscopy, and therefore characterized instrument response functions for a time-domain technique. We show that self-quenched uranin enables measurements free of the color effect, making it a superior choice for a lifetime reference over scattered light.
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Affiliation(s)
- Rafal Luchowski
- Center for Commercialization of Fluorescence Technologies (CCFT), Department of Molecular Biology & Immunology, UNTHSC, Fort Worth, TX 76107, USA
- Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland
| | - Sushant Sabnis
- Center for Commercialization of Fluorescence Technologies (CCFT), Department of Molecular Biology & Immunology, UNTHSC, Fort Worth, TX 76107, USA
| | - Mariusz Szabelski
- Center for Commercialization of Fluorescence Technologies (CCFT), Department of Molecular Biology & Immunology, UNTHSC, Fort Worth, TX 76107, USA
- Department of Physics and Biophysics, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland
| | - Pabak Sarkar
- Center for Commercialization of Fluorescence Technologies (CCFT), Department of Molecular Biology & Immunology, UNTHSC, Fort Worth, TX 76107, USA
| | - Sangram Raut
- Center for Commercialization of Fluorescence Technologies (CCFT), Department of Molecular Biology & Immunology, UNTHSC, Fort Worth, TX 76107, USA
| | - Zygmunt Gryczynski
- Center for Commercialization of Fluorescence Technologies (CCFT), Department of Molecular Biology & Immunology, UNTHSC, Fort Worth, TX 76107, USA
| | - Julian Borejdo
- Center for Commercialization of Fluorescence Technologies (CCFT), Department of Molecular Biology & Immunology, UNTHSC, Fort Worth, TX 76107, USA
| | - Piotr Bojarski
- Institute of Experimental Physics, University of Gdansk, Wita Stwosza 57, 80-952 Gdansk, Poland
| | - Ignacy Gryczynski
- Center for Commercialization of Fluorescence Technologies (CCFT), Department of Molecular Biology & Immunology, UNTHSC, Fort Worth, TX 76107, USA
- Department of Cell Biology and Anatomy, UNTHSC, Fort Worth, TX 76107, USA
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6
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Resch-Genger U, DeRose PC. Fluorescence standards: Classification, terminology, and recommendations on their selection, use, and production (IUPAC Technical Report). PURE APPL CHEM 2010. [DOI: 10.1351/pac-rep-09-09-02] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chromophore-based fluorescence standards for the characterization of photo-luminescence measuring systems and the determination of relevant fluorometric quantities are classified according to their scope and area of application. General and type-specific requirements for suitable standards are derived for each class of standards. Metrological requirements linked to the realization of comparable measurements are addressed and recommendations on selecting, using, and developing fluorescence standards are given.
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Affiliation(s)
- Ute Resch-Genger
- 1Federal Institute for Materials Research and Testing (BAM), Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany
| | - Paul C. DeRose
- 2National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD 20899-8312, USA
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McCranor BJ, Thompson RB. Long wavelength fluorescence lifetime standards for front-face fluorometry. J Fluoresc 2010; 20:435-40. [PMID: 19953311 PMCID: PMC2896289 DOI: 10.1007/s10895-009-0565-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Accepted: 11/03/2009] [Indexed: 10/20/2022]
Abstract
With the increased development and use of fluorescence lifetime-based sensors, fiber optic sensors, fluorescence lifetime imaging microscopy (FLIM), and plate and array readers, , calibration standards are essential to ensure the proper function of these devices and accurate results. For many devices that utilize a "front face excitation" geometry where the excitation is nearly coaxial with the direction of emission, scattering-based lifetime standards are problematic and fluorescent lifetime standards are necessary. As more long wavelength (red and near-infrared) fluorophores are used to avoid background autofluorescence, the lack of lifetime standards in this wavelength range has only become more apparent . We describe an approach to developing lifetime standards in any wavelength range, based on Förster resonance energy transfer (FRET). These standards are bright, highly reproducible, have a broad decrease in observed lifetime, and an emission wavelength in the red to near infrared making them well suited for the laboratory and field applications as well. This basic approach can be extended to produce lifetime standards for other wavelength regimes.
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Affiliation(s)
- Bryan J. McCranor
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201-1503, USA
| | - Richard B. Thompson
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201-1503, USA
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9
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Luchowski R, Gryczynski Z, Sarkar P, Borejdo J, Szabelski M, Kapusta P, Gryczynski I. Instrument response standard in time-resolved fluorescence. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2009; 80:033109. [PMID: 19334909 DOI: 10.1063/1.3095677] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The fluorescence of LDS 798 dye in aqueous solution has a very short lifetime of 24 ps, independent of excitation wavelength. The time response of common photon counting detectors depends on the wavelength of the registered photon. In lifetime measurements, the instrument response function (IRF) is usually approximated by the temporal profile of the scattered excitation light. Because lambda(Exc) is typically much shorter than lambda(Em), a systematic error may be present in these measurements. We demonstrate that the fluorescence decay of LDS 798 is a better approximation of IRF, in particular, for avalanche photodiodes used in the near infrared spectral region.
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Affiliation(s)
- Rafal Luchowski
- Department of Molecular Biology and Immunology, Center for Commercialization of Fluorescence Technologies, UNTHSC, Fort Worth, Texas 76107, USA
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10
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Kubicki AA. Solvent effects in time-resolved emission spectra of 4-dimethylamino-4′-methoxy-stilbene in different solvents. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.03.060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Chapter 15 Instrumentation for Fluorescence‐Based Fiber Optic Biosensors. Methods Enzymol 2008. [DOI: 10.1016/s0076-6879(08)03415-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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12
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Kelbauskas L, Dietel W. Internalization of Aggregated Photosensitizers by Tumor Cells: Subcellular Time-resolved Fluorescence Spectroscopy on Derivatives of Pyropheophorbide-a Ethers and Chlorin e6 under Femtosecond One- and Two-photon Excitation¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2002)0760686ioapbt2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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14
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Boens N, Qin W, Basarić N, Hofkens J, Ameloot M, Pouget J, Lefévre JP, Valeur B, Gratton E, vandeVen M, Silva ND, Engelborghs Y, Willaert K, Sillen A, Rumbles G, Phillips D, Visser AJWG, van Hoek A, Lakowicz JR, Malak H, Gryczynski I, Szabo AG, Krajcarski DT, Tamai N, Miura A. Fluorescence lifetime standards for time and frequency domain fluorescence spectroscopy. Anal Chem 2007; 79:2137-49. [PMID: 17269654 PMCID: PMC6816264 DOI: 10.1021/ac062160k] [Citation(s) in RCA: 267] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of fluorophores with single-exponential fluorescence decays in liquid solution at 20 degrees C were measured independently by nine laboratories using single-photon timing and multifrequency phase and modulation fluorometry instruments with lasers as excitation source. The dyes that can serve as fluorescence lifetime standards for time-domain and frequency-domain measurements are all commercially available, are photostable under the conditions of the measurements, and are soluble in solvents of spectroscopic quality (methanol, cyclohexane, water). These lifetime standards are anthracene, 9-cyanoanthracene, 9,10-diphenylanthracene, N-methylcarbazole, coumarin 153, erythrosin B, N-acetyl-l-tryptophanamide, 1,4-bis(5-phenyloxazol-2-yl)benzene, 2,5-diphenyloxazole, rhodamine B, rubrene, N-(3-sulfopropyl)acridinium, and 1,4-diphenylbenzene. At 20 degrees C, the fluorescence lifetimes vary from 89 ps to 31.2 ns, depending on fluorescent dye and solvent, which is a useful range for modern pico- and nanosecond time-domain or mega- to gigahertz frequency-domain instrumentation. The decay times are independent of the excitation and emission wavelengths. Dependent on the structure of the dye and the solvent, the excitation wavelengths used range from 284 to 575 nm, the emission from 330 to 630 nm. These lifetime standards may be used to either calibrate or test the resolution of time- and frequency-domain instrumentation or as reference compounds to eliminate the color effect in photomultiplier tubes. Statistical analyses by means of two-sample charts indicate that there is no laboratory bias in the lifetime determinations. Moreover, statistical tests show that there is an excellent correlation between the lifetimes estimated by the time-domain and frequency-domain fluorometries. Comprehensive tables compiling the results for 20 (fluorescence lifetime standard/solvent) combinations are given.
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Affiliation(s)
- Noël Boens
- To whom correspondence should be addressed. . Fax: +32-16-327 990. . Fax: + 32-11-268 599
| | | | | | | | - Marcel Ameloot
- To whom correspondence should be addressed. . Fax: +32-16-327 990. . Fax: + 32-11-268 599
| | | | - Jean-Pierre Lefévre
- CNRS UMR 8531, Laboratoire de Chimie Générale, CNAM, 292 rue Saint-Martin, F-75141 Paris Cedex 03, and Laboratoire PPSM, ENS-Cachan, 61 avenue du Président Wilson, 94235 Cachan Cedex, France
| | - Bernard Valeur
- CNRS UMR 8531, Laboratoire de Chimie Générale, CNAM, 292 rue Saint-Martin, F-75141 Paris Cedex 03, and Laboratoire PPSM, ENS-Cachan, 61 avenue du Président Wilson, 94235 Cachan Cedex, France
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, University of California, Biomedical Engineering Department, 3120 Natural Sciences II Building, Irvine, California 92697-2715
| | | | - Norberto D. Silva
- Laboratory for Fluorescence Dynamics, University of California, Biomedical Engineering Department, 3120 Natural Sciences II Building, Irvine, California 92697-2715
| | - Yves Engelborghs
- Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200G, 3001 Heverlee, Belgium
| | - Katrien Willaert
- Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200G, 3001 Heverlee, Belgium
| | - Alain Sillen
- Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200G, 3001 Heverlee, Belgium
| | - Garry Rumbles
- Department of Chemistry and Centre for Photomolecular Science, Imperial College, Exhibition Road, London SW7 2AY, United Kingdom
| | - David Phillips
- Department of Chemistry and Centre for Photomolecular Science, Imperial College, Exhibition Road, London SW7 2AY, United Kingdom
| | - Antonie J. W. G. Visser
- Departments of Biochemistry and Biophysics, MicroSpectroscopy Centre, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen The Netherlands
| | - Arie van Hoek
- Departments of Biochemistry and Biophysics, MicroSpectroscopy Centre, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen The Netherlands
| | - Joseph R. Lakowicz
- Center for Fluorescence Spectroscopy, Department of Biological Chemistry, University of Maryland, 660 W. Redwood Street, Baltimore Maryland 21201
| | - Henryk Malak
- Center for Fluorescence Spectroscopy, Department of Biological Chemistry, University of Maryland, 660 W. Redwood Street, Baltimore Maryland 21201
| | - Ignacy Gryczynski
- Center for Fluorescence Spectroscopy, Department of Biological Chemistry, University of Maryland, 660 W. Redwood Street, Baltimore Maryland 21201
| | - Arthur G. Szabo
- Faculty of Science, Wilfrid Laurier University, 75 University Avenue, Waterloo, Ontario N2L 3C5, Canada
| | - Don T. Krajcarski
- Faculty of Science, Wilfrid Laurier University, 75 University Avenue, Waterloo, Ontario N2L 3C5, Canada
| | | | - Atsushi Miura
- Department of Chemistry, School of Science, Kwansei Gakuin University, Uegahara1-1-155, Nishinomiya 662-8501, Japan
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Arzhantsev S, Zachariasse KA, Maroncelli M. Photophysics of trans-4-(Dimethylamino)-4‘-cyanostilbene and Its Use as a Solvation Probe. J Phys Chem A 2006; 110:3454-70. [PMID: 16526624 DOI: 10.1021/jp0559231] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electronic structure calculations, steady-state electronic spectroscopy, and femtosecond time-resolved emission spectroscopy are used to examine the photophysics of trans-4-(dimethylamino)-4'-cyanostilbene (DCS) and its solvent dependence. Semiempirical AM1/CI calculations suggest that an anilino TICT state is a potential candidate for the emissive state of DCS in polar solvents. But observation of large and solvent-independent absorption and emission transition moments in a number of solvents (M(abs) = 6.7 +/- 0.4 D and M(em) = 7.6 +/- 0.8 D) rule out the involvement of any such state, which would have a vanishingly small transition moment. The absorption and steady-state emission spectra of DCS evolve in a systematic manner with solvent polarity, approximately as would be expected for a single, highly polar excited state. Attempts to fit the solvatochromism of DCS using standard dielectric continuum models are only partially successful when values of the solute dipole moments suggested by independent measurements are assumed. The shapes of the absorption and emission spectra of DCS change systematically with solvent polarity in a manner that is semiquantitatively reproduced using a coupled-state model of the spectroscopy. Kerr-gate emission measurements show that the emission dynamics of DCS down to subpicosecond times reflect only solvent relaxation, rather than any more complicated electronic state kinetics. The spectral response functions measured with DCS are well correlated to those previously reported for the solvation probe coumarin 153, indicating DCS to be a useful alternative probe of solvation dynamics.
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Affiliation(s)
- Sergei Arzhantsev
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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16
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Malicka J, Gryczynski I, Lakowicz JR. Fluorescence spectral properties of labeled thiolated oligonucleotides bound to silver particles. Biopolymers 2004; 74:263-71. [PMID: 15150802 PMCID: PMC2763907 DOI: 10.1002/bip.20071] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We examined the fluorescent spectral properties of fluorescein-labeled DNA oligomers when directly bound to metallic silver particles via a terminal sulfhydryl group. We found a 12-fold increase in fluorescence intensity and 25-fold decrease in lifetime for a fluorescein residue positioned 23 nucleotides from the silver surface compared to labeled oligomers in free solution. Similar results were found for a 23-mer labeled with five fluorescein residues. The absence of long lifetime components in the intensity decays suggests that all labeled oligomers are bound to silver and affected similarly by the metallic surfaces. These results provide the basic knowledge needed to begin use of metal-enhanced fluorescence for the detection of target sequences in simple formats potentially without a washing separation step. The use of metal-enhanced fluorescence provides a generic approach to obtaining a hybridization-dependent increase in fluorescence with most, if not all, commonly used fluorophores.
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Affiliation(s)
- Joanna Malicka
- Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, MD 21201, USA
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17
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Grummt UW, Pautzsch T, Birckner E, Utterodt A, Neugebauer U, Klemm E. Photophysics of Poly{2,2′-bipyridine-5,5′-diylethynylene [2,5-di(2-ethylhexyl)oxy-1,4-phenylene[ethynylene}: a comparison with monomer and dimer model compounds. J PHYS ORG CHEM 2004. [DOI: 10.1002/poc.714] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Kelbauskas L, Dietel W. Internalization of aggregated photosensitizers by tumor cells: subcellular time-resolved fluorescence spectroscopy on derivatives of pyropheophorbide-a ethers and chlorin e6 under femtosecond one- and two-photon excitations. Photochem Photobiol 2002; 76:686-94. [PMID: 12511052 DOI: 10.1562/0031-8655(2002)076<0686:ioapbt>2.0.co;2] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Amphiphilic sensitizers self-associate in aqueous environments and form aggregated species that exhibit no or only negligible photodynamic activity. However, amphiphilic photosensitizers number among the most potent agents of photodynamic therapy. The processes by which these sensitizers are internalized into tumor cells have yet to be fully elucidated and thus remain the subject of debate. In this study the uptake of photosensitizer aggregates into tumor cells was examined directly using subcellular time-resolved fluorescence spectroscopy with a high temporal resolution (20-30 ps) and high sensitivity (time-correlated single-photon counting). The investigations were performed on selected sensitizers that exhibit short fluorescence decay times (< 50 ps) in aggregated form. Derivatives of pyropheophorbide-a ether and chlorin e6 with varying lipophilicity were used for the study. The characteristic fluorescence decay times and spectroscopic features of the sensitizer aggregates measured in aqueous solution also could be observed in A431 human endothelial carcinoma cells administered with these photosensitizers. This shows that tumor cells can internalize sensitizers in aggregated form. Uptake of aggregates and their monomerization inside cells were demonstrated directly for the first time by means of fluorescence lifetime imaging with a high temporal resolution. Internalization of the aggregates seems to be endocytosis mediated. The degree of their monomerization in tumor cells is strongly influenced by the lipophilicity of the compounds.
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Affiliation(s)
- L Kelbauskas
- Institute of Optics and Quantum Electronics, Friedrich-Schilier-University Jena, Jena, Germany.
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19
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Szmacinski H, Lakowicz JR. Fluorescence lifetime-based sensing and imaging. SENSORS AND ACTUATORS. B, CHEMICAL 1995; 29:16-24. [PMID: 33867678 PMCID: PMC8049533 DOI: 10.1016/0925-4005(95)01658-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Time-resolved fluorescence spectroscopy is presently regarded as a research tool in biochemistry, biophysics and chemical physics. However, time-resolved methods can also be used for chemical sensing. Lifetime-based sensing has several advantages over intensity-based methods. Since the lifetime is independent of the total probe intensity, its measurement can provide quantitative sensing of many analytes without the requirement for wavelength-ratiometric probes. Analytes like oxygen and halides can be determined by the collisional quenching mechanism. To date, lifetime probes for analyte recognition (binding) have been identified for Ca 2+, Mg 2 +, K + and pH. Importantly, the lifetime method provides a possibility to expand the sensitive analyte concentration range using probes with spectral shifts. The fluorescence lifetime method allows the sensing of analytes for which there are no direct probes, like glucose, antigens, or any affinity or immunoassays based on fluorescence energy transfer as the transduction mechanism. Advances in instrumentation, laser technology, fiber-optics and especially long-wavelength probes can result in the rapid migration of time-resolved fluorescence to clinical chemistry, environmental sensing and industrial applications. We shall describe phase-modulation instrumentation that can use simple light sources for which the light can be modulated externally by acoustooptic modulators or internally by driving current. Finally, we shall describe fluorescence lifetime imaging microscopy (FLIM), in which image contrast is created from the lifetime at each point of the image. Time-resolved imaging is now a reality in fluorescence microscopy, and promises to provide chemical imaging of a variety of intracellular analyte and/or cellular phenomena.
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Affiliation(s)
- Henryk Szmacinski
- Center of Fluorescence Spectroscopy, Department of Biological Chemistry, University of Maryland, School of Medicine, 108 N. Greene St., Baltimore, MD 21201, USA
| | - Joseph R Lakowicz
- Center of Fluorescence Spectroscopy, Department of Biological Chemistry, University of Maryland, School of Medicine, 108 N. Greene St., Baltimore, MD 21201, USA
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20
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Lakowicz JR, Gryczyński I, Kuśba J, Bogdanov V. Light quenching of fluorescence: a new method to control the excited state lifetime and orientation of fluorophores. Photochem Photobiol 1994; 60:546-62. [PMID: 7870760 DOI: 10.1111/j.1751-1097.1994.tb05147.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Experimental studies have recently demonstrated that fluorescence emission can be quenched by laser light pulses from modern high-repetition rate lasers, a phenomenon we call "light quenching." In this overview article, we describe the possible effects of light quenching on the steady-state and time-resolved intensity and anisotropy of fluorophores. One can imagine two classes of experiments. Light quenching can occur within the single excitation pulse, or light quenching can be accomplished with a second time-delayed quenching pulse. The extent of light quenching depends on the amplitude of the emission spectrum at the quenching wavelength. Different effects are expected for light quenching by a single laser beam (within a single laser pulse) or for a time-delayed quenching pulse. Depending upon the polarization of the light quenching beam, light quenching can decrease or increase the anisotropy. Remarkably, the light quenching can break the usual z-axis symmetry of the excited state population, and the measured anisotropy (or polarization) depends upon whether the observation axis is parallel or perpendicular to the propagation direction of the light quenching beam. The polarization can increase to unity under selected conditions. Quenching with time-delayed light pulses can result in step changes in the intensity or anisotropy, which is predicted to result in oscillations in the frequency-domain intensity and anisotropy decays. These predicted effects of light quenching, including oscillations in the frequency-domain data, were demonstrated to occur using selected fluorophores. The increasing availability and use of pulsed laser sources requires consideration of the possible effects of light quenching and offers the opportunity for a new class of two-pulse or multiple-pulse time-resolved experiments where the sample is prepared by the excitation pulse and subsequent quenching pulses to modify the excited state population, followed by time- or frequency-domain measurement of the optically prepared excited fluorophores.
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Affiliation(s)
- J R Lakowicz
- Department of Biological Chemistry, University of Maryland at Baltimore School of Medicine 21201
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Gryczynski I, Kuśba J, Lakowicz JR. Light Quenching of Fluorescence Using Time-Delayed Laser Pulses As Observed by Frequency-Domain Fluorometry. THE JOURNAL OF PHYSICAL CHEMISTRY 1994; 98:8886-8895. [PMID: 31902951 PMCID: PMC6941149 DOI: 10.1021/j100087a012] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We describe experimental observations of fluorescence quenching by time-delayed light pulses whose wavelength overlaps the emission spectrum of 4-(dimethylamino)-4'-cyanostilbene (DCS). The relative cross sections for light quenching were proportional to the amplitude of the emission spectra at the light quenching wavelength. The frequency-domain intensity and anisotropy decay measurements showed oscillations resulting from time-delayed light quenching. The amplitude of the oscillations depends upon the amount of light quenching. The frequency of the oscillations depends upon the delay between the excitation and quenching pulses. To the best of our knowledge, only a stepwise decrease in the intensity or anisotropy could produce such oscillations in the frequency-domain data. Light quenching of fluorescence is thus shown to provide a means to control the number and orientation of the excited fluorophores. The use of multiple light pulses for excitation and quenching can have far-reaching applications in the use of time-resolved fluorescence in physical chemistry and biophysics.
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Affiliation(s)
- Ignacy Gryczynski
- Center for Fluorescence Spectroscopy, Department of Biological Chemistry, University of Maryland at Baltimore, School of Medicine, 108 N. Greene Street, Baltimore, Maryland 21201
| | - Józef Kuśba
- Center for Fluorescence Spectroscopy, Department of Biological Chemistry, University of Maryland at Baltimore, School of Medicine, 108 N. Greene Street, Baltimore, Maryland 21201
| | - Joseph R Lakowicz
- Center for Fluorescence Spectroscopy, Department of Biological Chemistry, University of Maryland at Baltimore, School of Medicine, 108 N. Greene Street, Baltimore, Maryland 21201
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Gryczynski Z, Bucci E. A new front-face optical cell for measuring weak fluorescent emissions with time resolution in the picosecond time scale. Biophys Chem 1993; 48:31-8. [PMID: 8257765 DOI: 10.1016/0301-4622(93)80039-l] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Recent developments of ultrafast fluorimeters allow measuring time-resolved fluorescence on the picosecond time scale. This implies one is able to monitor lifetimes and anisotropy decays of highly quenched systems and of systems that contain fluorophores having lifetimes in the subnanosecond range; both systems that emit weak signals. The combination of weak signals and very short lifetimes makes the measurements prone to distortions which are negligible in standard fluorescence experiments. To cope with these difficulties, we have designed a new optical cell for front-face optics which offers to the excitation beam a horizontal free liquid surface in the absence of interactions with optical windows. The new cell has been tested with probes of known lifetimes and anisotropies. It proved very useful in detecting tryptophan fluorescence in hemoglobin. If only diluted samples are available, which cannot be used in front-face optics, regular square geometry can still be utilized by inserting light absorbers into a cuvette of 1 cm path length.
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Affiliation(s)
- Z Gryczynski
- Department of Biochemistry, University of Maryland at Baltimore 21201
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