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Jin D, Lu Y, Leif RC, Yang S, Rajendran M, Miller LW. How to build a time-gated luminescence microscope. ACTA ACUST UNITED AC 2014; 67:2.22.1-2.22.36. [PMID: 24510771 DOI: 10.1002/0471142956.cy0222s67] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The sensitivity of filter-based fluorescence microscopy techniques is limited by autofluorescence background. Time-gated detection is a practical way to suppress autofluorescence, enabling higher contrast and improved sensitivity. In the past few years, three groups of authors have demonstrated independent approaches to build robust versions of time-gated luminescence microscopes. Three detailed, step-by-step protocols are provided here for modifying standard fluorescent microscopes to permit imaging time-gated luminescence.
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Affiliation(s)
- Dayong Jin
- Advanced Cytometry Laboratories, MQ BioFocus Research Centre & Photonics Research Centre, Macquarie University, New South Wales, Australia
| | - Yiqing Lu
- Advanced Cytometry Laboratories, MQ BioFocus Research Centre & Photonics Research Centre, Macquarie University, New South Wales, Australia
| | | | - Sean Yang
- Newport Instruments, San Diego, California
| | - Megha Rajendran
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois
| | - Lawrence W Miller
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois
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Jin D. Demonstration of true-color high-contrast microorganism imaging for terbium bioprobes. Cytometry A 2011; 79:392-7. [DOI: 10.1002/cyto.a.21052] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 02/14/2011] [Accepted: 02/22/2011] [Indexed: 12/18/2022]
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Gahlaut N, Miller LW. Time-resolved microscopy for imaging lanthanide luminescence in living cells. Cytometry A 2010; 77:1113-25. [PMID: 20824630 DOI: 10.1002/cyto.a.20964] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 07/29/2010] [Accepted: 08/02/2010] [Indexed: 11/12/2022]
Abstract
Time-resolved luminescence (TRL) microscopy can image signals from lanthanide coordination complexes or other probes with long emission lifetimes, thereby eliminating short-lifetime (<100 ns) autofluorescence background from biological specimens. However, lanthanide complexes emit far fewer photons per unit time than conventional fluorescent probes, making it difficult to rapidly acquire high quality images at probe concentrations that are relevant to live cell experiments. This article describes the development and characterization of a TRL microscope that employs a light-emitting diode (LED, λ(em) = 365 nm) for pulsed epi-illumination and an intensified charge-coupled device (ICCD) camera for gated, widefield detection. Europium chelate-impregnated microspheres were used to evaluate instrument performance in terms of short-lifetime fluorescence background rejection, photon collection efficiency, image contrast, and signal-to-noise ratio (SNR). About 200 nm microspheres were imaged within the time resolution limit of the ICCD (66.7 ms) with complete autofluorescence suppression. About 40 nm microspheres containing ~400 chelate molecules were detected within ~1-s acquisition times. A luminescent terbium complex, Lumi4-Tb®, was introduced into the cytoplasm of cultured cells at an estimated concentration of 300 nM by the method of osmotic lysis of pinocytic vesicles. Time-resolved images of the living, terbium complex-loaded cells were acquired within acquisition times as short as 333 ms, and the effects of increased exposure time and frame summing on image contrast and SNR were evaluated. The performance analyses show that TRL microscopy is sufficiently sensitive and precise to allow high-resolution, quantitative imaging of lanthanide luminescence in living cells under physiologically relevant experimental conditions.
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Affiliation(s)
- Nivriti Gahlaut
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, IL 60607, USA
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Mathis G, Bazin H. Stable Luminescent Chelates and Macrocyclic Compounds. LANTHANIDE LUMINESCENCE 2010. [DOI: 10.1007/4243_2010_5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Leif RC, Yang S, Jin D, Piper J, Vallarino LM, Williams JW, Zucker RM. Calibration beads containing luminescent lanthanide ion complexes. JOURNAL OF BIOMEDICAL OPTICS 2009; 14:024022. [PMID: 19405752 DOI: 10.1117/1.3103646] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The reliability of lanthanide luminescence measurements, by both flow cytometry and digital microscopy, would be enhanced by the availability of narrowband emitting, UV excited lanthanide calibration beads. 0.5-, 3-, and 5-microm beads containing a luminescent europium-complex are manufactured. The luminescence distribution of the 5-microm beads is measured with a time-delayed light-scatter-gated luminescence flow cytometer to have a 7.0% coefficient of variation (CV) The spacial distribution of the europium-complex in individual beads is determined to be homogeneous by confocal microscopy. Emission peaks are found at 592, 616 (width 9.9 nm), and 685 nm with a PARISS spectrophotometer. The kinetics of the luminescence bleaching caused by UV irradiation of the 0.5- and 5-microm beads measured under LED excitation with a fluorescence microscope indicate that bleaching does not interfere with their imaging. The luminescence lifetimes in water and air were 340 and 460 micros, respectively. Thus, these 5-microm beads can be used for spectral calibration of microscopes equipped with a spectrograph, as test particles for time-delayed luminescence flow cytometers, and possibly as labels for macromolecules and cells.
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Affiliation(s)
- Robert C Leif
- Newport Instruments, 5648 Toyon Road, San Diego, California 92115-1022, USA.
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Jin D, Piper JA, Leif RC, Yang S, Ferrari BC, Yuan J, Wang G, Vallarino LM, Williams JW. Time-gated flow cytometry: an ultra-high selectivity method to recover ultra-rare-event mu-targets in high-background biosamples. JOURNAL OF BIOMEDICAL OPTICS 2009; 14:024023. [PMID: 19405753 DOI: 10.1117/1.3103770] [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
A fundamental problem for rare-event cell analysis is auto-fluorescence from nontarget particles and cells. Time-gated flow cytometry is based on the temporal-domain discrimination of long-lifetime (>1 micros) luminescence-stained cells and can render invisible all nontarget cell and particles. We aim to further evaluate the technique, focusing on detection of ultra-rare-event 5-microm calibration beads in environmental water dirt samples. Europium-labeled 5-microm calibration beads with improved luminescence homogeneity and reduced aggregation were evaluated using the prototype UV LED excited time-gated luminescence (TGL) flow cytometer (FCM). A BD FACSAria flow cytometer was used to sort accurately a very low number of beads (<100 events), which were then spiked into concentrated samples of environmental water. The use of europium-labeled beads permitted the demonstration of specific detection rates of 100%+/-30% and 91%+/-3% with 10 and 100 target beads, respectively, that were mixed with over one million nontarget autofluorescent background particles. Under the same conditions, a conventional FCM was unable to recover rare-event fluorescein isothiocyanate (FITC) calibration beads. Preliminary results on Giardia detection are also reported. We have demonstrated the scientific value of lanthanide-complex biolabels in flow cytometry. This approach may augment the current method that uses multifluorescence-channel flow cytometry gating.
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Affiliation(s)
- Dayong Jin
- Macquarie University, Centre of MQ Photonics, New South Wales 2109, Australia.
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Vámosi G, Damjanovich S, Szöllosi J. Dissecting interacting molecular populations by FRET. Cytometry A 2008; 73:681-4. [PMID: 18636568 DOI: 10.1002/cyto.a.20601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- György Vámosi
- Cell Biology and Signaling Research Group of the Hungarian Academy of Sciences, University of Debrecen, H-4032 Debrecen, Nagyerdei krt. 98, Hungary
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Abstract
The method of time-gated detection of long-lifetime (1-2,000 micros) luminescence-labeled microorganisms following rapid excitation pulses has proved highly efficient in suppressing nontarget autofluorescence (<0.1 micros), scatterings, and other prompt stray light (Hemmila and Mukkala, Crit Rev Clin Lab Sci 2001;38:441-519). The application of such techniques to flow cytometry is highly attractive but there are significant challenges in implementing pulsed operation mode to rapid continuous flowing sample to achieve high cell analysis rates (Leif R, Vallarino L, Rare-earth chelates as fluorescent markers in cell separation and analysis, In: Cell Separation Science and Technology, ACS Symposium Series 464, American Chemical Society, 1991, pp 41-58; Condrau et al., Cytometry 1994;16:187-194; Condrau et al., Cytometry 1994;16:195-205; Shapiro HM, Improving signals from labels: Amplification and other techniques, In: Practical Flow Cytometry, 4th ed., Wiley, New York, 2002, p 345). We present here practical approaches for achieving high cell analysis rates at 100% detection efficiency, using time-gated luminescence (TGL) flow cytometry. In particular, we report that new-generation UV LEDs are practical sources in TGL flow cytometry. Spatial effects of long-lived luminescence from the target fluorophore in a fast-flowing sample stream have been investigated; excitation and detection requirements in TGL flow cytometry were theoretically analyzed; two practical approaches, a triggered model and a continuous flow-section model, were considered as a function of flow speed, sizes and relative positions of the excitation/detection spots, label lifetime, excitation pulse duration/intensity, and detection duration. A particular configuration using LED excitation to detect europium dye-labeled targets in such a system has been modeled in detail. In the triggered model, TGL mode is confined to a low repetition rate (<1 kHz) and engaged only while a target particle is present in the excitation zone. In the flow-section model, TGL mode is engaged continuously at high repetition rates to permit much higher cell arrival rates. The detection of 5.7-microm europium calibration beads in a UV LED-excited TGL flow cytometer has been shown to be feasible with a calculated signal-to-background ratio up to 11:1.
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Affiliation(s)
- Dayong Jin
- Centre for Lasers and Applications, Division of Information and Communication Sciences, Macquarie University, NSW, Australia.
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Zucker RM, Rigby P, Clements I, Salmon W, Chua M. Reliability of confocal microscopy spectral imaging systems: Use of multispectral beads. Cytometry A 2007; 71:174-89. [PMID: 17266146 DOI: 10.1002/cyto.a.20371] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND There is a need for a standardized, impartial calibration, and validation protocol on confocal spectral imaging (CSI) microscope systems. To achieve this goal, it is necessary to have testing tools to provide a reproducible way to evaluate instrument performance. METHODS We evaluated fluorescent spectral beads (FocalCheck) from Molecular Probes/Invitrogen that consist of four pairs with emissions between 500 and 725 nm and a europium macrocycle quantum dye bead. These bead tools compliment our previously published protocol for testing spectral imaging systems that used an inexpensive multi-ion discharge lamp (MIDL) that contains Hg(+), Ar(+), and inorganic fluorophores that emits distinct, stable spectral features. RESULTS We acquired the spectra of the FocalCheck beads on a Zeiss 510 Meta, a Leica TCS-SP1, a Leica SP2 AOBS, an Olympus FV 1000, and a Nikon C1Si confocal systems and a PARISS microscopic spectral system and of the europium beads on the Leica TCS-SP1 and PARISS spectral imaging systems. A lack of performance with some equipment between 650 and 750 nm was identified using the far red pair of the FocalCheck beads. The position of the slider in front of PMT 2 that reflects light into PMT 1 and PMT 3 affected the measurement of all bead intensities. Unmixing algorithms were used to separate beads with different fluorochromes and separate two fluorochromes on the same bead. CONCLUSIONS The FocalCheck multi-spectral beads yielded similar profiles on four CSI systems and a PARISS spectral system. The utilization of the spectral FocalCheck beads is helpful to evaluate proper spectral performance, especially in the far red region. Europium beads provide a very narrow spectrum that can help to identify machines that have spectral problems. The dyes located on individual beads or mixed together in ring-core configuration can be used as test particles to demonstrate spectral unmixing with various algorithms.
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Affiliation(s)
- Robert M Zucker
- Reproductive Toxicology Division (MD-67), National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA. zucker.robert@.epa.gov
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Leif RC, Vallarino LM, Becker MC, Yang S. Increasing lanthanide luminescence by use of the RETEL effect. Cytometry A 2006; 69:940-6. [PMID: 16969811 DOI: 10.1002/cyto.a.20318] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Luminescent lanthanide complexes produce emissions with the narrowest-known width at half maximum; however, their significant use in cytometry required an increase in luminescence intensity. The companion review, Leif et al., Cytometry 2006;69A:767-778, described a new technique for the enhancement of lanthanide luminescence, the Resonance Energy Transfer Enhanced Luminescence (RETEL) effect, which increases luminescence and is compatible with standard slide microscopy. METHODS The luminescence of the europium ion macrocyclic complex, EuMac, was increased by employing the RETEL effect. After adding the nonluminescent gadolinium ion complex of the thenoyltrifluoroacetonate (TTFA) ligand or the sodium salt of TTFA in ethanol solution, the EuMac-labeled sample was allowed to dry. Both a conventional arc lamp and a time-gated UV LED served as light sources for microscopic imaging. The emission intensity was measured with a CCD camera. Multiple time-gated images were summed with special software to permit analysis and effective presentation of the final image. RESULTS With the RETEL effect, the luminescence of the EuMac-streptavidin conjugate increased at least six-fold upon drying. Nuclei of apoptotic cells were stained with DAPI and tailed with 5BrdUrd to which a EuMac-anti-5BrdU conjugate was subsequently attached. Time-gated images showed the long-lived EuMac luminescence but did not show the short-lived DAPI fluorescence. Imaging of DNA-synthesizing cells with an arc lamp showed that both S phase and apoptotic cells were labeled, and that their labeling patterns were different. The images of the luminescent EuMac and fluorescent DAPI were combined to produce a color image on a white background. This combination of simple chemistry, instrumentation, and presentation should make possible the inexpensive use of the lanthanide macrocycles, Quantum Dyes, as molecular diagnostics for cytological and histopathological microscopic imaging.
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