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Chen H, Ma N, Kagawa K, Kawahito S, Digman M, Gratton E. Widefield multifrequency fluorescence lifetime imaging using a two-tap complementary metal-oxide semiconductor camera with lateral electric field charge modulators. JOURNAL OF BIOPHOTONICS 2019; 12:e201800223. [PMID: 30421535 DOI: 10.1002/jbio.201800223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 10/30/2018] [Accepted: 11/09/2018] [Indexed: 06/09/2023]
Abstract
Widefield frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) measures the fluorescence lifetime of entire images in a fast and efficient manner. We report a widefield FD-FLIM system based on a complementary metal-oxide semiconductor camera equipped with two-tap true correlated double sampling lock-in pixels and lateral electric field charge modulators. Owing to the fast intrinsic response and modulation of the camera, our system allows parallel multifrequency FLIM in one measurement via fast Fourier transform. We demonstrate that at a fundamental frequency of 20 MHz, 31-harmonics can be measured with 64 phase images per laser repetition period. As a proof of principle, we analyzed cells transfected with Cerulean and with a construct of Cerulean-Venus that shows Förster Resonance Energy Transfer at different modulation frequencies. We also tracked the temperature change of living cells via the fluorescence lifetime of Rhodamine B at different frequencies. These results indicate that our widefield multifrequency FD-FLIM system is a valuable tool in the biomedical field.
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Affiliation(s)
- Hongtao Chen
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
| | - Ning Ma
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
| | - Keiichiro Kagawa
- Research Institute of Electronics, Shizuoka University, Hamamatsu, Shizuoka, Japan
| | - Shoji Kawahito
- Research Institute of Electronics, Shizuoka University, Hamamatsu, Shizuoka, Japan
| | - Michelle Digman
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
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Chen H, Holst G, Gratton E. Modulated CMOS camera for fluorescence lifetime microscopy. Microsc Res Tech 2015; 78:1075-81. [PMID: 26500051 DOI: 10.1002/jemt.22587] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 09/21/2015] [Indexed: 11/11/2022]
Abstract
Widefield frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) is a fast and accurate method to measure the fluorescence lifetime of entire images. However, the complexity and high costs involved in construction of such a system limit the extensive use of this technique. PCO AG recently released the first luminescence lifetime imaging camera based on a high frequency modulated CMOS image sensor, QMFLIM2. Here we tested and provide operational procedures to calibrate the camera and to improve the accuracy using corrections necessary for image analysis. With its flexible input/output options, we are able to use a modulated laser diode or a 20 MHz pulsed white supercontinuum laser as the light source. The output of the camera consists of a stack of modulated images that can be analyzed by the SimFCS software using the phasor approach. The nonuniform system response across the image sensor must be calibrated at the pixel level. This pixel calibration is crucial and needed for every camera settings, e.g. modulation frequency and exposure time. A significant dependency of the modulation signal on the intensity was also observed and hence an additional calibration is needed for each pixel depending on the pixel intensity level. These corrections are important not only for the fundamental frequency, but also for the higher harmonics when using the pulsed supercontinuum laser. With these post data acquisition corrections, the PCO CMOS-FLIM camera can be used for various biomedical applications requiring a large frame and high speed acquisition.
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Affiliation(s)
- Hongtao Chen
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering University of California, Irvine, California
| | | | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering University of California, Irvine, California
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Time-Resolved Emission Imaging Microscopy Using Phosphorescent Metal Complexes: Taking FLIM and PLIM to New Lengths. LUMINESCENT AND PHOTOACTIVE TRANSITION METAL COMPLEXES AS BIOMOLECULAR PROBES AND CELLULAR REAGENTS 2014. [DOI: 10.1007/430_2014_168] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Chen H, Gratton E. A practical implementation of multifrequency widefield frequency-domain fluorescence lifetime imaging microscopy. Microsc Res Tech 2013; 76:282-9. [PMID: 23296945 DOI: 10.1002/jemt.22165] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 11/26/2012] [Indexed: 11/10/2022]
Abstract
Widefield frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) is a fast and accurate method to measure the fluorescence lifetime, especially in kinetic studies in biomedical researches. However, the small range of modulation frequencies available in commercial instruments makes this technique limited in its applications. Herein, we describe a practical implementation of multifrequency widefield FD-FLIM using a pulsed supercontinuum laser and a direct digital synthesizer. In this instrument we use a pulse to modulate the image intensifier rather than the more conventional sine-wave modulation. This allows parallel multifrequency FLIM measurement using the Fast Fourier Transform and the cross-correlation technique, which permits precise and simultaneous isolation of individual frequencies. In addition, the pulse modulation at the cathode of image intensifier restores the loss of optical resolution caused by the defocusing effect when the cathode is sinusoidally modulated. Furthermore, in our implementation of this technique, data can be graphically analyzed by the phasor method while data are acquired, which allows easy fit-free lifetime analysis of FLIM images. Here, our measurements of standard fluorescent samples and a Föster resonance energy transfer pair demonstrate that the widefield multifrequency FLIM system is a valuable and simple tool in fluorescence imaging studies.
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Affiliation(s)
- Hongtao Chen
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California, USA
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MÜLLER M, GHAUHARALI R, VISSCHER K, BRAKENHOFF G. Double-pulse fluorescence lifetime imaging in confocal microscopy. J Microsc 2011. [DOI: 10.1111/j.1365-2818.1995.tb03547.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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6
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Wade MH, de Feijter AW, Frame MK. Quantitative fluorescence imaging techniques for the study of organization and signaling mechanisms in cells. METHODS OF BIOCHEMICAL ANALYSIS 2006; 37:117-41. [PMID: 8309365 DOI: 10.1002/9780470110584.ch3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- M H Wade
- Meridian Instruments, Okemos, Michigan
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7
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Dong CY, French T, So PT, Buehler C, Berland KM, Gratton E. Fluorescence-lifetime imaging techniques for microscopy. Methods Cell Biol 2004; 72:431-64. [PMID: 14719344 DOI: 10.1016/s0091-679x(03)72021-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Affiliation(s)
- Chen Y Dong
- Laboratory for Fluorescence Dynamics, Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Gratton E, Breusegem S, Sutin J, Ruan Q, Barry N. Fluorescence lifetime imaging for the two-photon microscope: time-domain and frequency-domain methods. JOURNAL OF BIOMEDICAL OPTICS 2003; 8:381-90. [PMID: 12880343 DOI: 10.1117/1.1586704] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Fluorescence lifetime images are obtained with the laser scanning microscope using two methods: the time-correlated single-photon counting method and the frequency-domain method. In the same microscope system, we implement both methods. We perform a comparison of the performance of the two approaches in terms of signal-to-noise ratio (SNR) and the speed of data acquisition. While in our practical implementation the time-correlated single-photon counting technique provides a better SNR for low-intensity images, the frequency-domain method is faster and provides less distortion for bright samples.
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Affiliation(s)
- Enrico Gratton
- University of Illinois at Urbana-Champaign, Laboratory for Fluorescence Dynamics, 1110 West Green Street Urbana, Illinois 61801, USA.
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Brelje TC, Wessendorf MW, Sorenson RL. Multicolor laser scanning confocal immunofluorescence microscopy: practical application and limitations. Methods Cell Biol 2003; 70:165-244. [PMID: 12512325 DOI: 10.1016/s0091-679x(02)70006-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- T Clark Brelje
- Department of Cell Biology and Neuroanatomy, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
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Clegg RM, Holub O, Gohlke C. Fluorescence lifetime-resolved imaging: measuring lifetimes in an image. Methods Enzymol 2003; 360:509-42. [PMID: 12622166 DOI: 10.1016/s0076-6879(03)60126-6] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have given an overview of what one can gain by lifetime-resolved imaging and reviewed the major issues concerning lifetime-resolved measurements and FLI instrumentation. Instead of giving diverse selected examples, we have discussed the underlying basic pathways of deexcitation available to the molecules in the excited state. It is by traversing these pathways that compete kinetically with the fluorescence pathway of deactivation--and therefore affect the measured fluorescence lifetime--that we gain the information that lifetime-resolved fluorescence provides. It is hoped that being aware of the diversity, of pathways available to an excited fluorophore will facilitate potential users to recognize the value of FLI measurements and inspire innovative experiments using lifetime-resolved imaging. FLI gives us the ability within a fluorescence image of measuring and quantifying dynamic events taking place in the immediate surroundings of fluorophores as well as locating the fluorescent components within the image. Just as measurements in cuvettes, lifetime-resolved imaging extends considerably the potential information that can be derived from a fluorescence experiment. Our purpose has been to arouse an appreciation for the broad application of fluorescence lifetime-resolved measurements in imaging. We have given only general design characteristics of the instrumentation and discussed the characteristics that distinguish imaging from the single channel lifetime-resolved measurements. We have not provided details of the instrumentation or the presented many examples. These are available in the literature, and given in the references, and they are continually and rapidly growing.
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Affiliation(s)
- Robert M Clegg
- Department of Physics, University of Illinois Urbana-Champaign, Urbana 61801, USA
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Mitchell AC, Wall JE, Murray JG, Morgan CG. Direct modulation of the effective sensitivity of a CCD detector: a new approach to time-resolved fluorescence imaging. J Microsc 2002; 206:225-32. [PMID: 12067367 DOI: 10.1046/j.1365-2818.2002.01029.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In this paper a novel approach to frequency-domain fluorescence lifetime imaging (FLIM) is described. In a CCD camera a single pixel is defined by a charge pattern on a group of electrodes. By modulation of the pattern of voltages defining the pixel structure it is possible to modulate the sensitivity of the CCD at radio frequency. The modulation enhances the noise performance of the CCD, in contrast to the deterioration in performance seen when an intensifier stage is similarly modulated. The new technology has potential applications to a wide range of assays as well as in conventional FLIM applications. Unlike intensifier-based systems, the directly modulated CCD is physically small, inexpensive, robust and offers superior resolution and noise performance.
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Affiliation(s)
- A C Mitchell
- Photonic Research Systems Ltd, Peel Building, The Crescent, Salford M5 4WT, UK
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Schönle A, Glatz M, Hell SW. Four-dimensional multiphoton microscopy with time-correlated single-photon counting. APPLIED OPTICS 2000; 39:6306-11. [PMID: 18354639 DOI: 10.1364/ao.39.006306] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We report on the implementation of fluorescence-lifetime imaging in multiphoton excitation microscopy that uses PC-compatible modules for time-correlated single-photon counting. Four-dimensional data stacks are produced with each pixel featuring fluorescence-decay curves that consist of as many as 4096 bins. Fluorescence lifetime(s) and their amplitude(s) are extracted by statistical methods at each pixel or in arbitrarily defined regions of interest. When employing an avalanche photodiode the width of the temporal response function is 420 ps. Although this response confines the temporal resolution to values greater than several hundreds of picoseconds, the lifetime precision is determined by the signal-to-noise ratio and can be in the range of tens of picosconds. Lifetime changes are visualized in pulsed-laser-deposited fluorescent layers as well as in cyan fluorescent proteins that transfer energy to yellow fluorescent proteins in live mammalian cells.
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Affiliation(s)
- A Schönle
- High Resolution Optical Microscopy Group, Max-Planck-Institute for Biophysical Chemistry, D-37070 Göttingen, Germany
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13
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Buehler C, Dong CY, So PT, French T, Gratton E. Time-resolved polarization imaging by pump-probe (stimulated emission) fluorescence microscopy. Biophys J 2000; 79:536-49. [PMID: 10866979 PMCID: PMC1300957 DOI: 10.1016/s0006-3495(00)76315-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
We report the application of pump-probe fluorescence microscopy in time-resolved polarization imaging. We derived the equations governing the pump-probe stimulated emission process and characterized the pump and probe laser power levels for signal saturation. Our emphasis is to use this novel methodology to image polarization properties of fluorophores across entire cells. As a feasibility study, we imaged a 15-microm orange latex sphere and found that there is depolarization that is possibly due to energy transfer among fluorescent molecules inside the sphere. We also imaged a mouse fibroblast labeled with CellTracker Orange CMTMR (5-(and-6)-(((4-chloromethyl)benzoyl)amino)tetramethyl-rhodamine). We observed that Orange CMTMR complexed with gluthathione rotates fast, indicating the relatively low fluid-phase viscosity of the cytoplasmic microenvironment as seen by Orange CMTMR. The measured rotational correlation time ranged from approximately 30 to approximately 150 ps. This work demonstrates the effectiveness of stimulated emission measurements in acquiring high-resolution, time-resolved polarization information across the entire cell.
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Affiliation(s)
- C Buehler
- Novartis Pharma AG, Pharma Research, CTA, LFU/NAT S-360.4.16, CH-4002 Basel, Switzerland
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Tramier M, Kemnitz K, Durieux C, Coppey J, Denjean P, Pansu RB, Coppey-Moisan M. Restrained torsional dynamics of nuclear DNA in living proliferative mammalian cells. Biophys J 2000; 78:2614-27. [PMID: 10777758 PMCID: PMC1300851 DOI: 10.1016/s0006-3495(00)76806-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Physical parameters, describing the state of chromatinized DNA in living mammalian cells, were revealed by in situ fluorescence dynamic properties of ethidium in its free and intercalated states. The lifetimes and anisotropy decays of this cationic chromophore were measured within the nuclear domain, by using the ultra-sensitive time-correlated single-photon counting technique, confocal microscopy, and ultra-low probe concentrations. We found that, in living cells: 1) free ethidium molecules equilibrate between extracellular milieu and nucleus, demonstrating that the cation is naturally transported into the nucleus; 2) the intercalation of ethidium into chromatinized DNA is strongly inhibited, with relaxation of the inhibition after mild (digitonin) cell treatment; 3) intercalation sites are likely to be located in chromatin DNA; and 4) the fluorescence anisotropy relaxation of intercalated molecules is very slow. The combination of fluorescence kinetic and fluorescence anisotropy dynamics indicates that the torsional dynamics of nuclear DNA is highly restrained in living cells.
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Affiliation(s)
- M Tramier
- Institut Jacques Monod, UMR 7592, CNRS, Universités P 6/P 7, 75251 Paris cedex 05, France
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15
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French T, So PT, Dong CY, Berland KM, Gratton E. Fluorescence lifetime imaging techniques for microscopy. Methods Cell Biol 1998; 56:277-304. [PMID: 9500143 DOI: 10.1016/s0091-679x(08)60431-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- T French
- LJL Bio-Systems, Sunnyvale, California 94089, USA
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16
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Brismar H, Ulfhake B. Fluorescence lifetime measurements in confocal microscopy of neurons labeled with multiple fluorophores. Nat Biotechnol 1997; 15:373-7. [PMID: 9094141 DOI: 10.1038/nbt0497-373] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In order to resolve multiple fluorophores by their lifetimes in discrete tissue domains, the labeling intensity must be sufficiently strong and the intensity-difference between the labels must not be too large, the rate of fading should be similar for all fluorophores, and the lifetimes of the fluorophores should be sufficiently discrete. We could readily distinguish Cyanine-3.18 (Cy-3), Lissamine Rhodamine (LRSC), and Texas Red when they were not colocalized in tissue profiles. Colocalization of Cy-3 and LRSC, as well as Cy3 and Texas Red, could also be distinguished, while the combination of LRSC and Texas Red was more difficult. We have used fluorescence lifetime recordings in confocal microscopy to detect different neuropeptides in neurons. We demonstrate that somatostatin and galanin are colocalized in axon profiles of the spinal cord dorsal horn.
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Affiliation(s)
- H Brismar
- Royal Institute of Technology, Stockholm, Sweden.
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17
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Morgan CG, Mitchell AC, Murray JG, Wall EJ. New approaches to lifetime-resolved luminescence imaging. J Fluoresc 1997. [DOI: 10.1007/bf02764579] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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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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21
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Verwoerd NP, Hennink EJ, Bonnet J, Van der Geest CR, Tanke HJ. Use of ferro-electric liquid crystal shutters for time-resolved fluorescence microscopy. CYTOMETRY 1994; 16:113-7. [PMID: 7924679 DOI: 10.1002/cyto.990160204] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A technique is described to modify a standard fluorescence microscope for time-resolved visualization of delayed luminescing substances with decay times from 50 microseconds to several milliseconds. The modification consists of synchronized operation of a mechanical shutter, positioned in an aperture plane in the excitation pathway, simultaneously with a ferro-electric liquid crystal (FLC) shutter on the emission side. Operation of the microscope is through a microprocessor interfaced keypad by which all timing parameters can be adjusted for optimal suppression of fast decaying luminescence. Accuracy of the timing was within 1 microsecond. Prompt fluorescence was suppressed up to 10(6) times, as determined for bright prompt fluorescing microspheres. The use of the FLC shutter resulted in a reduction in emission intensity by a factor of 8 (due to the use of polarizers, the lower transmission of the FLC devices, and IR blocking filters). No significant image degradation due to shutter operations was observed. The modified microscope was successfully used for the visualization of delayed luminescing immunolabels, such as inorganic phosphor particles and lanthanide chelates, as well as naturally phosphorescing materials.
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Affiliation(s)
- N P Verwoerd
- Department of Cytochemistry and Cytometry, University of Leiden, The Netherlands
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22
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Fluorescence lifetime imaging microscopy (FLIM): Spatial resolution of microstructures on the nanosecond time scale. Biophys Chem 1993. [DOI: 10.1016/0301-4622(93)85012-7] [Citation(s) in RCA: 287] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Brelje TC, Wessendorf MW, Sorenson RL. Multicolor laser scanning confocal immunofluorescence microscopy: practical application and limitations. Methods Cell Biol 1993; 38:97-181. [PMID: 8246789 DOI: 10.1016/s0091-679x(08)61001-8] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- T C Brelje
- Department of Cell Biology and Neuroanatomy, University of Minnesota Medical School, Minneapolis 55455
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Åslund N, Carlsson K. Confocal scanning microfluorometry of dual-labelled specimens using two excitation wavelengths and lock-in detection technique. Micron 1993. [DOI: 10.1016/0968-4328(93)90038-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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25
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Wang XF, Periasamy A, Herman B, Coleman DM. Fluorescence Lifetime Imaging Microscopy (FLIM): Instrumentation and Applications. Crit Rev Anal Chem 1992. [DOI: 10.1080/10408349208051651] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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