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Faklaris O, Bancel-Vallée L, Dauphin A, Monterroso B, Frère P, Geny D, Manoliu T, de Rossi S, Cordelières FP, Schapman D, Nitschke R, Cau J, Guilbert T. Quality assessment in light microscopy for routine use through simple tools and robust metrics. J Biophys Biochem Cytol 2022; 221:213512. [PMID: 36173380 PMCID: PMC9526251 DOI: 10.1083/jcb.202107093] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 04/04/2022] [Accepted: 08/31/2022] [Indexed: 11/22/2022] Open
Abstract
Although there is a need to demonstrate reproducibility in light microscopy acquisitions, the lack of standardized guidelines monitoring microscope health status over time has so far impaired the widespread use of quality control (QC) measurements. As scientists from 10 imaging core facilities who encounter various types of projects, we provide affordable hardware and open source software tools, rigorous protocols, and define reference values to assess QC metrics for the most common fluorescence light microscopy modalities. Seven protocols specify metrics on the microscope resolution, field illumination flatness, chromatic aberrations, illumination power stability, stage drift, positioning repeatability, and spatial-temporal noise of camera sensors. We designed the MetroloJ_QC ImageJ/Fiji Java plugin to incorporate the metrics and automate analysis. Measurements allow us to propose an extensive characterization of the QC procedures that can be used by any seasoned microscope user, from research biologists with a specialized interest in fluorescence light microscopy through to core facility staff, to ensure reproducible and quantifiable microscopy results.
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Affiliation(s)
- Orestis Faklaris
- Montpellier Ressources Imagerie, Biocampus, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Leslie Bancel-Vallée
- Montpellier Ressources Imagerie, Biocampus, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Aurélien Dauphin
- Unite Genetique et Biologie du Développement U934, PICT-IBiSA, Institut Curie, INSERM, CNRS, PSL Research University, Paris, France
| | - Baptiste Monterroso
- Prism, Institut de Biologie Valrose, CNRS UMR 7277, INSERM 1091, University of Nice Sophia Antipolis - Parc Valrose, Nice, France
| | - Perrine Frère
- Plate-forme d'Imagerie de Tenon, UMR_S 1155, Hôpital Tenon, Paris, France
| | - David Geny
- Institut de Psychiatrie Et Neurosciences de Paris, INSERM U1266, Paris, France
| | - Tudor Manoliu
- Gustave Roussy, Université Paris-Saclay, Plate-forme Imagerie et Cytométrie, UMS AMMICa. Villejuif, France
| | - Sylvain de Rossi
- Montpellier Ressources Imagerie, Biocampus, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Fabrice P Cordelières
- University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, UMS 3420, US 4, Bordeaux, France
| | - Damien Schapman
- Université of Rouen Normandie, INSERM, Plate-Forme de Recherche en Imagerie Cellulaire de Normandie, Rouen, France
| | - Roland Nitschke
- Life Imaging Center and Signalling Research Centres CIBSS and BIOSS, University Freiburg, Freiburg, Germany
| | - Julien Cau
- Montpellier Ressources Imagerie, Biocampus, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Thomas Guilbert
- Institut Cochin, INSERM (U1016), CNRS (UMR 8104), Universite de Paris (UMR-S1016), Paris, France
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Browning CM, Mayes S, Mayes SA, Rich TC, Leavesley SJ. Microscopy is better in color: development of a streamlined spectral light path for real-time multiplex fluorescence microscopy. BIOMEDICAL OPTICS EXPRESS 2022; 13:3751-3772. [PMID: 35991911 PMCID: PMC9352297 DOI: 10.1364/boe.453657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 05/24/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
Spectroscopic image data has provided molecular discrimination for numerous fields including: remote sensing, food safety and biomedical imaging. Despite the various technologies for acquiring spectral data, there remains a trade-off when acquiring data. Typically, spectral imaging either requires long acquisition times to collect an image stack with high spectral specificity or acquisition times are shortened at the expense of fewer spectral bands or reduced spatial sampling. Hence, new spectral imaging microscope platforms are needed to help mitigate these limitations. Fluorescence excitation-scanning spectral imaging is one such new technology, which allows more of the emitted signal to be detected than comparable emission-scanning spectral imaging systems. Here, we have developed a new optical geometry that provides spectral illumination for use in excitation-scanning spectral imaging microscope systems. This was accomplished using a wavelength-specific LED array to acquire spectral image data. Feasibility of the LED-based spectral illuminator was evaluated through simulation and benchtop testing and assessment of imaging performance when integrated with a widefield fluorescence microscope. Ray tracing simulations (TracePro) were used to determine optimal optical component selection and geometry. Spectral imaging feasibility was evaluated using a series of 6-label fluorescent slides. The LED-based system response was compared to a previously tested thin-film tunable filter (TFTF)-based system. Spectral unmixing successfully discriminated all fluorescent components in spectral image data acquired from both the LED and TFTF systems. Therefore, the LED-based spectral illuminator provided spectral image data sets with comparable information content so as to allow identification of each fluorescent component. These results provide proof-of-principle demonstration of the ability to combine output from many discrete wavelength LED sources using a double-mirror (Cassegrain style) optical configuration that can be further modified to allow for high speed, video-rate spectral image acquisition. Real-time spectral fluorescence microscopy would allow monitoring of rapid cell signaling processes (i.e., Ca2+ and other second messenger signaling) and has potential to be translated to clinical imaging platforms.
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Affiliation(s)
- Craig M. Browning
- Chemical and Biomolecular Engineering, University of South Alabama, AL 36688, USA
- Systems Engineering, University of South Alabama, AL 36688, USA
- These authors contributed equally to this work
| | - Samantha Mayes
- Chemical and Biomolecular Engineering, University of South Alabama, AL 36688, USA
- These authors contributed equally to this work
| | - Samuel A. Mayes
- Chemical and Biomolecular Engineering, University of South Alabama, AL 36688, USA
- Systems Engineering, University of South Alabama, AL 36688, USA
| | - Thomas C. Rich
- Pharmacology, University of South Alabama, AL 36688, USA
- Center for Lung Biology, University of South Alabama, AL 36688, USA
| | - Silas J. Leavesley
- Chemical and Biomolecular Engineering, University of South Alabama, AL 36688, USA
- Pharmacology, University of South Alabama, AL 36688, USA
- Center for Lung Biology, University of South Alabama, AL 36688, USA
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3
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Hoffmann K, Nirmalananthan-Budau N, Resch-Genger U. Fluorescence calibration standards made from broadband emitters encapsulated in polymer beads for fluorescence microscopy and flow cytometry. Anal Bioanal Chem 2020; 412:6499-6507. [PMID: 32409890 PMCID: PMC7442758 DOI: 10.1007/s00216-020-02664-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 03/31/2020] [Accepted: 04/15/2020] [Indexed: 01/31/2023]
Abstract
We present here the design and characterization of a set of spectral calibration beads. These calibration beads are intended for the determination and regular control of the spectral characteristics of fluorescence microscopes and other fluorescence measuring devices for the readout of bead-based assays. This set consists of micrometer-sized polymer beads loaded with dyes from the liquid Calibration Kit Spectral Fluorescence Standards developed and certified by BAM for the wavelength-dependent determination of the spectral responsivity of fluorescence measuring devices like spectrofluorometers. To cover the wavelength region from 400 to 800 nm, two new near-infrared emissive dyes were included, which were spectroscopically characterized in solution and encapsulated in the beads. The resulting set of beads presents the first step towards a new platform of spectral calibration beads for the determination of the spectral characteristics of fluorescence instruments like fluorescence microscopes, FCM setups, and microtiter plate readers, thereby meeting the increasing demand for reliable and comparable fluorescence data especially in strongly regulated areas, e.g., medical diagnostics. This will eventually provide the basis for standardized calibration procedures for imaging systems as an alternative to microchannel slides containing dye solutions previously reported by us. Graphical abstract.
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Affiliation(s)
- Katrin Hoffmann
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Str. 11, 12489, Berlin, Germany
| | | | - Ute Resch-Genger
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Str. 11, 12489, Berlin, Germany.
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Abstract
BACKGROUND After fluorochromes are incorporated into cells, tissues, and organisms, confocal microscopy can be used to observe three-dimensional structures. LysoTracker Red (LT) is a paraformaldehyde-fixable probe that concentrates into acidic compartments of cells and indicates regions of high lysosomal activity and phagocytosis, both of which correlate to apoptotic activity. Thus, LT is a good indicator of apoptosis visualized by confocal microscopy. Results of LT staining of apoptotic cell death correlate well with other whole mount apoptosis vital dyes such as Nile blue sulfate and neutral red, with the added benefit of being fixable in situ. Nile blue sulfate can also be used as a non-vital, nonspecific dye to visualize general morphology. Stains such as acridine orange can be used for surface staining of fixed embryos to yield confocal images that are similar to scanning electron micrographs. METHODS Mouse embryos were stained with LT, fixed with paraformaldehyde/glutaraldehyde, dehydrated with methanol (MEOH), and cleared with benzyl alcohol/benzyl benzoate (BABB). Following this treatment, the tissues were nearly transparent. Embryos are mounted on depression slides, and serial sections are imaged by confocal microscopy, followed by 3-D reconstruction. RESULTS Embryos or tissues as thick as 500 microns (μm) can be visualized after clearing with BABB. LysoTracker staining reveals apoptotic regions in organogenesis-stage mouse embryos. Morphological observation of tissue was facilitated by combining autofluorescence with Nile blue sulfate staining of fixed embryos or opaque surface staining with acridine orange staining. CONCLUSIONS The use of BABB for clearing LT vital-stained and fixed embryos matches the refractive index of the tissue to the suspending medium, allowing increased penetration of laser light in a confocal microscope. Nile blue sulfate used as a non-vital dye provides a nonspecific staining of fixed embryos that can then be cleared with methyl salicylate for confocal observation. Sample preparation and staining procedures described here, with optimization of confocal laser scanning microscopy, allow for the detection and visualization of morphological structure and apoptosis in embryos up to 500 μm thick, and stained specimens can be fixed and mounted on depression slides.
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Abstract
STED microscopy images of live or fixed brain tissue contain a wealth of geometric information about cellular structures down to the scale of individual dendritic spines and axonal structures. To extract such morphological data in a credible way, several considerations regarding image acquisition and analysis must be taken into account. This chapter highlights the parameters of primary importance for acquiring and analyzing STED images and interpreting STED microscopy data.
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Affiliation(s)
- Martin O Lenz
- Cambridge Advanced Imaging Centre, University of Cambridge, Cambridge, UK
| | - Jan Tønnesen
- Achucarro Basque Center for Neuroscience, Leioa, Spain.
- Department of Neurosciences, Faculty of Medicine and Dentistry, University of the Basque Country (UPV/EHU), Leioa, Spain.
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6
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Abstract
Labeling fixed brain tissue with fluorescent synaptic and cellular markers can help assess circuit connectivity. Despite the diffraction-limited resolution of light microscopy there are several approaches to identify synaptic contacts onto a cell-of-interest. Understanding which image quantification methods can be applied to estimate cellular and synaptic connectivity at the light microscope level is beneficial to answer a range of questions, from mapping appositions between cellular structures or synaptic proteins to assessing synaptic contact density onto a cell-of-interest. This chapter provides the reader with details of the image analysis methods that can be applied to quantify in situ connectivity patterns at the level of cellular contacts and synaptic appositions.
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Affiliation(s)
- Mrinalini Hoon
- Department of Biological Structure, University of Washington, Seattle, 98195, WA, USA.
| | - Raunak Sinha
- Department of Physiology and Biophysics, University of Washington, Seattle, 98195, WA, USA
| | - Haruhisa Okawa
- Department of Biological Structure, University of Washington, Seattle, 98195, WA, USA.
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7
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Butzlaff M, Weigel A, Ponimaskin E, Zeug A. eSIP: A Novel Solution-Based Sectioned Image Property Approach for Microscope Calibration. PLoS One 2015; 10:e0134980. [PMID: 26244982 PMCID: PMC4526552 DOI: 10.1371/journal.pone.0134980] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 07/15/2015] [Indexed: 11/20/2022] Open
Abstract
Fluorescence confocal microscopy represents one of the central tools in modern sciences. Correspondingly, a growing amount of research relies on the development of novel microscopic methods. During the last decade numerous microscopic approaches were developed for the investigation of various scientific questions. Thereby, the former qualitative imaging methods became replaced by advanced quantitative methods to gain more and more information from a given sample. However, modern microscope systems being as complex as they are, require very precise and appropriate calibration routines, in particular when quantitative measurements should be compared over longer time scales or between different setups. Multispectral beads with sub-resolution size are often used to describe the point spread function and thus the optical properties of the microscope. More recently, a fluorescent layer was utilized to describe the axial profile for each pixel, which allows a spatially resolved characterization. However, fabrication of a thin fluorescent layer with matching refractive index is technically not solved yet. Therefore, we propose a novel type of calibration concept for sectioned image property (SIP) measurements which is based on fluorescent solution and makes the calibration concept available for a broader number of users. Compared to the previous approach, additional information can be obtained by application of this extended SIP chart approach, including penetration depth, detected number of photons, and illumination profile shape. Furthermore, due to the fit of the complete profile, our method is less susceptible to noise. Generally, the extended SIP approach represents a simple and highly reproducible method, allowing setup independent calibration and alignment procedures, which is mandatory for advanced quantitative microscopy.
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Affiliation(s)
- Malte Butzlaff
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Hannover, Germany
| | - Arwed Weigel
- Carl Zeiss Microscopy GmbH, Kistlerhofstr. 75, München, Germany
| | - Evgeni Ponimaskin
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Hannover, Germany
| | - Andre Zeug
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Hannover, Germany
- * E-mail:
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8
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Ikoma H, Heshmat B, Wetzstein G, Raskar R. Attenuation-corrected fluorescence spectra unmixing for spectroscopy and microscopy. OPTICS EXPRESS 2014; 22:19469-19483. [PMID: 25321030 DOI: 10.1364/oe.22.019469] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In fluorescence measurements, light is often absorbed and scattered by a sample both for excitation and emission, resulting in the measured spectra to be distorted. Conventional linear unmixing methods computationally separate overlapping spectra but do not account for these effects. We propose a new algorithm for fluorescence unmixing that accounts for the attenuation-related distortion effect on fluorescence spectra. Using a matrix representation, we derive forward measurement formation and a corresponding inverse method; the unmixing algorithm is based on nonnegative matrix factorization. We also demonstrate how this method can be extended to a higher-dimensional tensor form, which is useful for unmixing overlapping spectra observed under the attenuation effect in spectral imaging microscopy. We evaluate the proposed methods in simulation and experiments and show that it outperforms a conventional, linear unmixing method when absorption and scattering contributes to the measured signals, as in deep tissue imaging.
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9
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Monitoring intracellular oxidative events using dynamic spectral unmixing microscopy. Methods 2014; 66:345-52. [DOI: 10.1016/j.ymeth.2013.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 06/06/2013] [Accepted: 06/07/2013] [Indexed: 11/19/2022] Open
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10
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Abstract
A confocal microscope was evaluated with a series of tests that measure field illumination, lens clarity, laser power, laser stability, dichroic functionality, spectral registration, axial resolution, scanning stability, PMT quality, overall machine stability, and system noise. These tests will help investigators measure various parameters on their confocal microscopes to insure that they are working correctly with the necessary resolution, sensitivity, and precision. Utilization of this proposed testing approach will help eliminate some of the subjectivity currently employed in assessing the CLSM performance.
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Affiliation(s)
- Robert M Zucker
- Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
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11
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12
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Oreopoulos J, Berman R, Browne M. Spinning-disk confocal microscopy: present technology and future trends. Methods Cell Biol 2014; 123:153-75. [PMID: 24974027 DOI: 10.1016/b978-0-12-420138-5.00009-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Live-cell imaging requires not only high temporal resolution but also illumination powers low enough to minimize photodamage. Traditional single-point laser scanning confocal microscopy (LSCM) is generally limited by both the relatively slow speed at which it can acquire optical sections by serial raster scanning (a few Hz) and the higher potential for phototoxicity. These limitations have driven the development of rapid, parallel forms of confocal microscopy, the most popular of which is the spinning-disk confocal microscope (SDCM). Here, we briefly introduce the SDCM technique, discuss its strengths and weaknesses against LSCM, and update the reader on some recent developments in SDCM technology that improve its performance and expand its utility for life science research now and in the future.
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Affiliation(s)
| | - Richard Berman
- Spectral Applied Research, Richmond Hill, Ontario, Canada
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13
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Cole RW, Thibault M, Bayles CJ, Eason B, Girard AM, Jinadasa T, Opansky C, Schulz K, Brown CM. International test results for objective lens quality, resolution, spectral accuracy and spectral separation for confocal laser scanning microscopes. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2013; 19:1653-1668. [PMID: 24103552 DOI: 10.1017/s1431927613013470] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
As part of an ongoing effort to increase image reproducibility and fidelity in addition to improving cross-instrument consistency, we have proposed using four separate instrument quality tests to augment the ones we have previously reported. These four tests assessed the following areas: (1) objective lens quality, (2) resolution, (3) accuracy of the wavelength information from spectral detectors, and (4) the accuracy and quality of spectral separation algorithms. Data were received from 55 laboratories located in 18 countries. The largest source of errors across all tests was user error which could be subdivided between failure to follow provided protocols and improper use of the microscope. This truly emphasizes the importance of proper rigorous training and diligence in performing confocal microscopy experiments and equipment evaluations. It should be noted that there was no discernible difference in quality between confocal microscope manufactures. These tests, as well as others previously reported, will help assess the quality of confocal microscopy equipment and will provide a means to track equipment performance over time. From 62 to 97% of the data sets sent in passed the various tests demonstrating the usefulness and appropriateness of these tests as part of a larger performance testing regiment.
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Affiliation(s)
- Richard W Cole
- New York State Department of Health, Wadsworth Center, P.O. Box 509, Albany, NY 12201, USA
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14
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Hng KI, Dormann D. ConfocalCheck--a software tool for the automated monitoring of confocal microscope performance. PLoS One 2013; 8:e79879. [PMID: 24224017 PMCID: PMC3818239 DOI: 10.1371/journal.pone.0079879] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/26/2013] [Indexed: 11/30/2022] Open
Abstract
Laser scanning confocal microscopy has become an invaluable tool in biomedical research but regular quality testing is vital to maintain the system's performance for diagnostic and research purposes. Although many methods have been devised over the years to characterise specific aspects of a confocal microscope like measuring the optical point spread function or the field illumination, only very few analysis tools are available. Our aim was to develop a comprehensive quality assurance framework ranging from image acquisition to automated analysis and documentation. We created standardised test data to assess the performance of the lasers, the objective lenses and other key components required for optimum confocal operation. The ConfocalCheck software presented here analyses the data fully automatically. It creates numerous visual outputs indicating potential issues requiring further investigation. By storing results in a web browser compatible file format the software greatly simplifies record keeping allowing the operator to quickly compare old and new data and to spot developing trends. We demonstrate that the systematic monitoring of confocal performance is essential in a core facility environment and how the quantitative measurements obtained can be used for the detailed characterisation of system components as well as for comparisons across multiple instruments.
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Affiliation(s)
- Keng Imm Hng
- MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Dirk Dormann
- MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London, United Kingdom
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15
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Arsov Z, Urbančič I, Garvas M, Biglino D, Ljubetič A, Koklič T, Štrancar J. Fluorescence microspectroscopy as a tool to study mechanism of nanoparticles delivery into living cancer cells. BIOMEDICAL OPTICS EXPRESS 2011; 2:2083-2095. [PMID: 21833349 PMCID: PMC3149510 DOI: 10.1364/boe.2.2083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 06/03/2011] [Accepted: 06/27/2011] [Indexed: 05/31/2023]
Abstract
Lack of better understanding of nanoparticles targeted delivery into cancer cells calls for advanced optical microscopy methodologies. Here we present a development of fluorescence microspectroscopy (spectral imaging) based on a white light spinning disk confocal microscope with emission wavelength selection by a liquid crystal tunable filter. Spectral contrasting of images was used to localize polymer nanoparticles and cell membranes labeled with fluorophores that have substantially overlapping spectra. In addition, fluorescence microspectroscopy enabled spatially-resolved detection of small but significant effects of local molecular environment on the properties of environment-sensitive fluorescent probe. The observed spectral shift suggests that the delivery of suitably composed cancerostatic alkylphospholipid nanoparticles into living cancer cells might rely on the fusion with plasma cell membrane.
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Affiliation(s)
- Zoran Arsov
- Laboratory of Biophysics, Department of Solid State Physics, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Center of Excellence NAMASTE, Jamova 39, 1000 Ljubljana, Slovenia
| | - Iztok Urbančič
- Laboratory of Biophysics, Department of Solid State Physics, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Maja Garvas
- Laboratory of Biophysics, Department of Solid State Physics, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Daniele Biglino
- Laboratory of Biophysics, Department of Solid State Physics, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Center of Excellence NAMASTE, Jamova 39, 1000 Ljubljana, Slovenia
| | - Ajasja Ljubetič
- Laboratory of Biophysics, Department of Solid State Physics, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Tilen Koklič
- Laboratory of Biophysics, Department of Solid State Physics, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Center of Excellence NAMASTE, Jamova 39, 1000 Ljubljana, Slovenia
| | - Janez Štrancar
- Laboratory of Biophysics, Department of Solid State Physics, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Center of Excellence NAMASTE, Jamova 39, 1000 Ljubljana, Slovenia
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16
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Zucker RM, Chua M. Evaluation and purchase of confocal microscopes: numerous factors to consider. ACTA ACUST UNITED AC 2011; Chapter 2:Unit2.16. [PMID: 20938918 DOI: 10.1002/0471142956.cy0216s54] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The purchase of a confocal microscope is a difficult decision. Many factors need to be considered, which include hardware, software, company, support, service, and price. These issues are discussed to help guide the purchasing process.
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Affiliation(s)
- Robert M Zucker
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Toxicology Assessment Division, Research Triangle Park, North Carolina, USA
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17
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Gibbs-Flournoy EA, Bromberg PA, Hofer TPJ, Samet JM, Zucker RM. Darkfield-confocal microscopy detection of nanoscale particle internalization by human lung cells. Part Fibre Toxicol 2011; 8:2. [PMID: 21247485 PMCID: PMC3033333 DOI: 10.1186/1743-8977-8-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 01/19/2011] [Indexed: 11/10/2022] Open
Abstract
Background Concerns over the health effects of nanomaterials in the environment have created a need for microscopy methods capable of examining the biological interactions of nanoparticles (NP). Unfortunately, NP are beyond the diffraction limit of resolution for conventional light microscopy (~200 nm). Fluorescence and electron microscopy techniques commonly used to examine NP interactions with biological substrates have drawbacks that limit their usefulness in toxicological investigation of NP. EM is labor intensive and slow, while fluorescence carries the risk of photobleaching the sample and has size resolution limits. In addition, many relevant particles lack intrinsic fluorescence and therefore can not be detected in this manner. To surmount these limitations, we evaluated the potential of a novel combination of darkfield and confocal laser scanning microscopy (DF-CLSM) for the efficient 3D detection of NP in human lung cells. The DF-CLSM approach utilizes the contrast enhancements of darkfield microscopy to detect objects below the diffraction limit of 200 nm based on their light scattering properties and interfaces it with the power of confocal microscopy to resolve objects in the z-plane. Results Validation of the DF-CLSM method using fluorescent polystyrene beads demonstrated spatial colocalization of particle fluorescence (Confocal) and scattered transmitted light (Darkfield) along the X, Y, and Z axes. DF-CLSM imaging was able to detect and provide reasonable spatial locations of 27 nm TiO2 particles in relation to the stained nuclei of exposed BEAS 2B cells. Statistical analysis of particle proximity to cellular nuclei determined a significant difference between 5 min and 2 hr particle exposures suggesting a time-dependant internalization process. Conclusions DF-CLSM microscopy is an alternative to current conventional light and electron microscopy methods that does not rely on particle fluorescence or contrast in electron density. DF-CLSM is especially well suited to the task of establishing the spatial localization of nanoparticles within cells, a critical topic in nanotoxicology. This technique has advantages to 2D darkfield microscopy as it visualizes nanoparticles in 3D using confocal microscopy. Use of this technique should aid toxicological studies related to observation of NP interactions with biological endpoints at cellular and subcellular levels.
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Affiliation(s)
- Eugene A Gibbs-Flournoy
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Chapel Hill, NC, USA
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18
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Cheng WY, Tong H, Miller EW, Chang CJ, Remington J, Zucker RM, Bromberg PA, Samet JM, Hofer TP. An integrated imaging approach to the study of oxidative stress generation by mitochondrial dysfunction in living cells. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:902-8. [PMID: 20413366 PMCID: PMC2920907 DOI: 10.1289/ehp.0901811] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 04/22/2010] [Indexed: 05/13/2023]
Abstract
BACKGROUND The mechanisms of action of many environmental agents commonly involve oxidative stress resulting from mitochondrial dysfunction. Zinc is a common environmental metallic contaminant that has been implicated in a variety of oxidant-dependent toxicological responses. Unlike ions of other transition metals such as iron, copper, and vanadium, Zn(2+) does not generate reactive oxygen species (ROS) through redox cycling. OBJECTIVE To characterize the role of oxidative stress in zinc-induced toxicity. METHODS We used an integrated imaging approach that employs the hydrogen peroxide (H2O2)-specific fluorophore Peroxy Green 1 (PG1), the mitochondrial potential sensor 5,5 ,6,6 -tetrachloro-1,1 ,3,3 -tetraethylbenzimidazolylcarbocyanine iodide (JC-1), and the mitochondria-targeted form of the redox-sensitive genetically encoded fluorophore MTroGFP1 in living cells. RESULTS Zinc treatment in the presence of the Zn(2+) ionophore pyrithione of A431 skin carcinoma cells preloaded with the H(2)O(2)-specific indicator PG1 resulted in a significant increase in H(2)O(2) production that could be significantly inhibited with the mitochondrial inhibitor carbonyl cyanide 3-chlorophenylhydrazone. Mitochondria were further implicated as the source of zinc-induced H(2)O(2) formation by the observation that exposure to zinc caused a loss of mitochondrial membrane potential. Using MTroGFP1, we showed that zinc exposure of A431 cells induces a rapid loss of reducing redox potential in mitochondria. We also demonstrated that zinc exposure results in rapid swelling of mitochondria isolated from mouse hearts. CONCLUSION Taken together, these findings show a disruption of mitochondrial integrity, H(2)O(2) formation, and a shift toward positive redox potential in cells exposed to zinc. These data demonstrate the utility of real-time, live-cell imaging to study the role of oxidative stress in toxicological responses.
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Affiliation(s)
- Wan-Yun Cheng
- Department of Environmental Sciences and Engineering, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - Haiyan Tong
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Chapel Hill, North Carolina, USA
| | - Evan W. Miller
- Department of Chemistry and the Howard Hughes Medical Institute, University of California–Berkeley, Berkeley, California, USA
| | - Christopher J. Chang
- Department of Chemistry and the Howard Hughes Medical Institute, University of California–Berkeley, Berkeley, California, USA
| | - James Remington
- Department of Physics, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Robert M. Zucker
- Toxicology Assessment Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Philip A. Bromberg
- Center for Environmental Medicine and Lung Biology, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - James M. Samet
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Chapel Hill, North Carolina, USA
- Address correspondence to J.M. Samet, 104 Mason Farm Rd., EPA Human Studies Facility, Chapel Hill, NC 27599-7315 USA. Telephone: (919) 966-0665. Fax: (919) 962-6271. E-mail:
| | - Thomas P.J. Hofer
- Helmholtz Zentrum München, German Research Center for Environmental Health, Clinical Cooperation Group Inflammatory Lung Diseases, Gauting, Germany
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Hierarchical functional gradients of pH-responsive self-assembled monolayers using dynamic covalent chemistry on surfaces. Nat Chem 2009; 1:649-56. [DOI: 10.1038/nchem.400] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 09/08/2009] [Indexed: 11/08/2022]
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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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Spectral unmixing: analysis of performance in the olfactory bulb in vivo. PLoS One 2009; 4:e4418. [PMID: 19198655 PMCID: PMC2635473 DOI: 10.1371/journal.pone.0004418] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Accepted: 12/23/2008] [Indexed: 11/25/2022] Open
Abstract
Background The generation of transgenic mice expressing combinations of fluorescent proteins has greatly aided the reporting of activity and identification of specific neuronal populations. Methods capable of separating multiple overlapping fluorescence emission spectra, deep in the living brain, with high sensitivity and temporal resolution are therefore required. Here, we investigate to what extent spectral unmixing addresses these issues. Methodology/Principal Findings Using fluorescence resonance energy transfer (FRET)-based reporters, and two-photon laser scanning microscopy with synchronous multichannel detection, we report that spectral unmixing consistently improved FRET signal amplitude, both in vitro and in vivo. Our approach allows us to detect odor-evoked FRET transients 180–250 µm deep in the brain, the first demonstration of in vivo spectral imaging and unmixing of FRET signals at depths greater than a few tens of micrometer. Furthermore, we determine the reporter efficiency threshold for which FRET detection is improved by spectral unmixing. Conclusions/Significance Our method allows the detection of small spectral variations in depth in the living brain, which is essential for imaging efficiently transgenic animals expressing combination of multiple fluorescent proteins.
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Comparability of Fluorescence Microscopy Data and Need for Instrument Characterization of Spectral Scanning Microscopes. SPRINGER SERIES ON FLUORESCENCE 2008. [DOI: 10.1007/4243_2008_028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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