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Cannon TM, Lagarto JL, Dyer BT, Garcia E, Kelly DJ, Peters NS, Lyon AR, French PMW, Dunsby C. Characterization of NADH fluorescence properties under one-photon excitation with respect to temperature, pH, and binding to lactate dehydrogenase. OSA CONTINUUM 2021; 4:1610-1625. [PMID: 34458690 PMCID: PMC8367293 DOI: 10.1364/osac.423082] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 05/06/2023]
Abstract
Reduced nicotinamide adenine dinucleotide (NADH) is the principal electron donor in glycolysis and oxidative metabolism and is thus recognized as a key biomarker for probing metabolic state. While the fluorescence characteristics of NADH have been investigated extensively, there are discrepancies in the published data due to diverse experimental conditions, instrumentation and microenvironmental parameters that can affect NADH fluorescence. Using a cuvette-based time-resolved spectrofluorimeter employing one-photon excitation at 375 nm, we characterized the fluorescence intensity, lifetime, spectral response, anisotropy and time-resolved anisotropy of NADH in aqueous solution under varying microenvironmental conditions, namely temperature, pH, and binding to lactate dehydrogenase (LDH). Our results demonstrate how temperature, pH, and binding partners each impact the fluorescence signature of NADH and highlight the complexity of the fluorescence data when different parameters produce competing effects. We hope that the data presented in this study will provide a reference for potential sources of variation in experiments measuring NADH fluorescence.
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Affiliation(s)
- Taylor M. Cannon
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
- These authors contributed equally to this work and are listed in alphabetical order
| | - Joao L. Lagarto
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
- These authors contributed equally to this work and are listed in alphabetical order
| | - Benjamin T. Dyer
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Edwin Garcia
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
| | - Douglas J. Kelly
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
| | - Nicholas S. Peters
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Alexander R. Lyon
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | | | - Chris Dunsby
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
- Centre for Pathology, Imperial College London, London, W12 0NN, UK
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2
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Lagarto JL, Villa F, Tisa S, Zappa F, Shcheslavskiy V, Pavone FS, Cicchi R. Real-time multispectral fluorescence lifetime imaging using Single Photon Avalanche Diode arrays. Sci Rep 2020; 10:8116. [PMID: 32415224 PMCID: PMC7229199 DOI: 10.1038/s41598-020-65218-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 04/24/2020] [Indexed: 12/19/2022] Open
Abstract
Autofluorescence spectroscopy has emerged in recent years as a powerful tool to report label-free contrast between normal and diseased tissues, both in vivo and ex vivo. We report the development of an instrument employing Single Photon Avalanche Diode (SPAD) arrays to realize real-time multispectral autofluorescence lifetime imaging at a macroscopic scale using handheld single-point fibre optic probes, under bright background conditions. At the detection end, the fluorescence signal is passed through a transmission grating and both spectral and temporal information are encoded in the SPAD array. This configuration allows interrogation in the spectral range of interest in real time. Spatial information is provided by an external camera together with a guiding beam that provides a visual reference that is tracked in real-time. Through fast image processing and data analysis, fluorescence lifetime maps are augmented on white light images to provide feedback of the measurements in real-time. We validate and demonstrate the practicality of this technique in the reference fluorophores and in articular cartilage samples mimicking the degradation that occurs in osteoarthritis. Our results demonstrate that SPADs together with fibre probes can offer means to report autofluorescence spectral and lifetime contrast in real-time and thus are suitable candidates for in situ tissue diagnostics.
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Affiliation(s)
- João L Lagarto
- National Institute of Optics National Research Council (INO-CNR), Largo Enrico Fermi 6, 50125, Florence, Italy.
- European Laboratory for Non-linear Spectroscopy (LENS), Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy.
| | - Federica Villa
- Dipartimento di Elettronica, Informazione e Bioingegneria (DEIB), Politecnico di Milano, 20133, Milan, Italy
| | - Simone Tisa
- Micro Photon Device SRL, Via Waltraud Gebert Deeg 3g, I-39100, Bolzano, Italy
| | - Franco Zappa
- Dipartimento di Elettronica, Informazione e Bioingegneria (DEIB), Politecnico di Milano, 20133, Milan, Italy
| | - Vladislav Shcheslavskiy
- Becker & Hickl GmbH, Nunsdorfer Ring 7-9, 12277, Berlin, Germany
- Privolzhskiy Medical Research University, 603005, Nizhny Novgorod, Russia
| | - Francesco S Pavone
- National Institute of Optics National Research Council (INO-CNR), Largo Enrico Fermi 6, 50125, Florence, Italy
- European Laboratory for Non-linear Spectroscopy (LENS), Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy
- Department of Physics, University of Florence, Via G. Sansone 1, 50019, Sesto Fiorentino, Italy
| | - Riccardo Cicchi
- National Institute of Optics National Research Council (INO-CNR), Largo Enrico Fermi 6, 50125, Florence, Italy
- European Laboratory for Non-linear Spectroscopy (LENS), Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy
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3
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Poudel C, Mela I, Kaminski CF. High-throughput, multi-parametric, and correlative fluorescence lifetime imaging. Methods Appl Fluoresc 2020; 8:024005. [PMID: 32028271 PMCID: PMC8208541 DOI: 10.1088/2050-6120/ab7364] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 12/18/2019] [Accepted: 02/06/2020] [Indexed: 12/11/2022]
Abstract
In this review, we discuss methods and advancements in fluorescence lifetime imaging microscopy that permit measurements to be performed at faster speed and higher resolution than previously possible. We review fast single-photon timing technologies and the use of parallelized detection schemes to enable high-throughput and high content imaging applications. We appraise different technological implementations of fluorescence lifetime imaging, primarily in the time-domain. We also review combinations of fluorescence lifetime with other imaging modalities to capture multi-dimensional and correlative information from a single sample. Throughout the review, we focus on applications in biomedical research. We conclude with a critical outlook on current challenges and future opportunities in this rapidly developing field.
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Affiliation(s)
- Chetan Poudel
- Department of Chemical Engineering and Biotechnology,
Philippa Fawcett Drive, University of
Cambridge, Cambridge CB3 0AS, United
Kingdom
| | - Ioanna Mela
- Department of Chemical Engineering and Biotechnology,
Philippa Fawcett Drive, University of
Cambridge, Cambridge CB3 0AS, United
Kingdom
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology,
Philippa Fawcett Drive, University of
Cambridge, Cambridge CB3 0AS, United
Kingdom
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Lagarto JL, Nickdel MB, Kelly DJ, Price A, Nanchahal J, Dunsby C, French P, Itoh Y. Autofluorescence Lifetime Reports Cartilage Damage in Osteoarthritis. Sci Rep 2020; 10:2154. [PMID: 32034262 PMCID: PMC7005742 DOI: 10.1038/s41598-020-59219-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 01/27/2020] [Indexed: 11/09/2022] Open
Abstract
Osteoarthritis (OA) is the most common arthritis and its hallmark is degradation of articular cartilage by proteolytic enzymes leading to loss of joint function. It is challenging to monitor the status of cartilage in vivo and this study explores the use of autofluorescence lifetime (AFL) measurements to provide a label-free optical readout of cartilage degradation that could enable earlier detection and evaluation of potential therapies. We previously reported that treatment of ex vivo porcine cartilage with proteolytic enzymes resulted in decreased AFL. Here we report changes in AFL of ex vivo mouse knee joints, porcine metacarpophalangeal joints, normal human metatarsophalangeal articular tissue and human OA tibial plateau tissues measured with or without treatment using a compact single-point time resolved spectrofluorometer. Our data show that proteolytically damaged areas in porcine metacarpophalangeal joints present a reduced AFL and that inducing aggrecanases in mouse and human joints also significantly reduces AFL. Further, human cartilage from OA patients presents a significantly lower AFL compared to normal human cartilage. Our data suggest that AFL can detect areas of cartilage erosion and may potentially be utilised as a minimally-invasive diagnostic readout for early stage OA in combination with arthroscopy devices.
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Affiliation(s)
- João L Lagarto
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
| | - Mohammad B Nickdel
- Kennedy Institute of Rheumatology, University of Oxford, Oxford, OX3 7FY, UK
| | - Douglas J Kelly
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
| | - Andrew Price
- Botner Research Centre, University of Oxford, Oxford, OX3 7LD, UK
| | - Jagdeep Nanchahal
- Kennedy Institute of Rheumatology, University of Oxford, Oxford, OX3 7FY, UK
| | - Chris Dunsby
- Department of Physics, Imperial College London, London, SW7 2AZ, UK.,Centre for Pathology, Imperial College London, London, SW7 2AZ, UK
| | - Paul French
- Department of Physics, Imperial College London, London, SW7 2AZ, UK.
| | - Yoshifumi Itoh
- Kennedy Institute of Rheumatology, University of Oxford, Oxford, OX3 7FY, UK.
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5
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Lagarto JL, Dyer BT, Peters NS, French PMW, Dunsby C, Lyon AR. In vivo label-free optical monitoring of structural and metabolic remodeling of myocardium following infarction. BIOMEDICAL OPTICS EXPRESS 2019; 10:3506-3521. [PMID: 31360603 PMCID: PMC6640823 DOI: 10.1364/boe.10.003506] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/15/2019] [Accepted: 05/29/2019] [Indexed: 05/14/2023]
Abstract
Cardiac remodeling following myocardial infarction (MI) involves structural and functional alterations in the infarcted and remote viable myocardium that can ultimately lead to heart failure. The underlying mechanisms are not fully understood and, following our previous study of the autofluorescence lifetime and diffuse reflectance signatures of the myocardium in vivo at 16 weeks post MI in rats [Biomed. Opt. Express6(2), 324 (2015)], we here present data obtained at 1, 2 and 4 weeks post myocardial infarction that help follow the temporal progression of these changes. Our results demonstrate that both structural and metabolic changes in the heart can be monitored from the earliest time points following MI using label-free optical readouts, not only in the region of infarction but also in the remote non-infarcted myocardium. Changes in the autofluorescence intensity and lifetime parameters associated with collagen type I autofluorescence were indicative of progressive collagen deposition in tissue that was most pronounced at earlier time points and in the region of infarction. In addition to significant collagen deposition in infarcted and non-infarcted myocardium, we also report changes in the autofluorescence parameters associated with reduced nicotinamide adenine (phosphate) dinucleotide (NAD(P)H) and flavin adenine dinucleotide (FAD), which we associate with metabolic alterations throughout the heart. Parallel measurements of the diffuse reflectance spectra indicated an increased contribution of reduced cytochrome c. Our findings suggest that combining time-resolved spectrofluorometry and diffuse reflectance spectroscopy could provide a useful means to monitor cardiac function in vivo at the time of surgery.
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Affiliation(s)
- João L. Lagarto
- Photonics Group, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ, United Kingdom
- Authors contributed equally to this work
| | - Benjamin T. Dyer
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN, United Kingdom
- Authors contributed equally to this work
| | - Nicholas S. Peters
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN, United Kingdom
- Centre for Cardiac Engineering, Imperial College London, Du Cane Road, London, W12 0NN, United Kingdom
| | - Paul M. W. French
- Photonics Group, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ, United Kingdom
| | - Chris Dunsby
- Photonics Group, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ, United Kingdom
- Centre for Pathology, Imperial College London Du Cane Road, London W12 0NN, United Kingdom
- Authors contributed equally to this work
| | - Alexander R. Lyon
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN, United Kingdom
- Authors contributed equally to this work
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6
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Lagarto J, Hares JD, Dunsby C, French PMW. Development of Low-Cost Instrumentation for Single Point Autofluorescence Lifetime Measurements. J Fluoresc 2017; 27:1643-1654. [PMID: 28540652 PMCID: PMC5583312 DOI: 10.1007/s10895-017-2101-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/04/2017] [Indexed: 01/25/2023]
Abstract
Autofluorescence lifetime measurements, which can provide label-free readouts in biological tissues, contrasting e.g. different types and states of tissue matrix components and different cellular metabolites, may have significant clinical potential for diagnosis and to provide surgical guidance. However, the cost of the instrumentation typically used currently presents a barrier to wider implementation. We describe a low-cost single point time-resolved autofluorescence instrument, exploiting modulated laser diodes for excitation and FPGA-based circuitry for detection, together with a custom constant fraction discriminator. Its temporal accuracy is compared against a "gold-standard" instrument incorporating commercial TCSPC circuitry by resolving the fluorescence decays of reference fluorophores presenting single and double exponential decay profiles. To illustrate the potential to read out intrinsic contrast in tissue, we present preliminary measurements of autofluorescence lifetime measurements of biological tissues ex vivo. We believe that the lower cost of this instrument could enhance the potential of autofluorescence lifetime metrology for clinical deployment and commercial development.
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Affiliation(s)
- João Lagarto
- Photonics Group, Department of Physics, Imperial College London, London, SW7 2AZ, UK.
| | - Jonathan D Hares
- Kentech Instruments Ltd., Howbery Park, Wallingford, OX10 8BD, UK
| | - Christopher Dunsby
- Photonics Group, Department of Physics, Imperial College London, London, SW7 2AZ, UK
| | - Paul M W French
- Photonics Group, Department of Physics, Imperial College London, London, SW7 2AZ, UK
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7
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Noble E, Kumar S, Görlitz FG, Stain C, Dunsby C, French PMW. In vivo label-free mapping of the effect of a photosystem II inhibiting herbicide in plants using chlorophyll fluorescence lifetime. PLANT METHODS 2017; 13:48. [PMID: 28638436 PMCID: PMC5472976 DOI: 10.1186/s13007-017-0201-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 06/08/2017] [Indexed: 06/19/2023]
Abstract
BACKGROUND In order to better understand and improve the mode of action of agrochemicals, it is useful to be able to visualize their uptake and distribution in vivo, non-invasively and, ideally, in the field. Here we explore the potential of plant autofluorescence (specifically chlorophyll fluorescence) to provide a readout of herbicide action across the scales utilising multiphoton-excited fluorescence lifetime imaging, wide-field single-photon excited fluorescence lifetime imaging and single point fluorescence lifetime measurements via a fibre-optic probe. RESULTS Our studies indicate that changes in chlorophyll fluorescence lifetime can be utilised as an indirect readout of a photosystem II inhibiting herbicide activity in living plant leaves at three different scales: cellular (~μm), single point (~1 mm2) and macroscopic (~8 × 6 mm2 of a leaf). Multiphoton excited fluorescence lifetime imaging of Triticum aestivum leaves indicated that there is an increase in the spatially averaged chlorophyll fluorescence lifetime of leaves treated with Flagon EC-a photosystem II inhibiting herbicide. The untreated leaf exhibited an average lifetime of 560 ± 30 ps while the leaf imaged 2 h post treatment exhibited an increased lifetime of 2000 ± 440 ps in different fields of view. The results from in vivo wide-field single-photon excited fluorescence lifetime imaging excited at 440 nm indicated an increase in chlorophyll fluorescence lifetime from 521 ps in an untreated leaf to 1000 ps, just 3 min after treating the same leaf with Flagon EC, and to 2150 ps after 27 min. In vivo single point fluorescence lifetime measurements demonstrated a similar increase in chlorophyll fluorescence lifetime. Untreated leaf presented a fluorescence lifetime of 435 ps in the 440 nm excited chlorophyll channel, CH4 (620-710 nm). In the first 5 min after treatment, mean fluorescence lifetime is observed to have increased to 1 ns and then to 1.3 ns after 60 min. For all these in vivo plant autofluorescence lifetime measurements, the plants were not dark-adapted. CONCLUSIONS We demonstrate that the local impact of a photosystem II herbicide on living plant leaves can be conveniently mapped in space and time via changes in autofluorescence lifetime, which we attribute to changes in chlorophyll fluorescence. Using portable fibre-optic probe instrumentation originally designed for label-free biomedical applications, this capability could be deployed outside the laboratory for monitoring the distribution of herbicides in growing plants.
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Affiliation(s)
- Elizabeth Noble
- Photonics Group, Department of Physics, Imperial College London, London, SW7 2AZ UK
- Department of Chemistry, Imperial College London, London, SW7 2AZ UK
- Institute of Chemical Biology, Imperial College London, London, SW7 2AZ UK
| | - Sunil Kumar
- Photonics Group, Department of Physics, Imperial College London, London, SW7 2AZ UK
| | - Frederik G. Görlitz
- Photonics Group, Department of Physics, Imperial College London, London, SW7 2AZ UK
| | - Chris Stain
- Syngenta, Jealott’s Hill International Research Centre, Bracknell, Berkshire RG42 6EY UK
| | - Chris Dunsby
- Photonics Group, Department of Physics, Imperial College London, London, SW7 2AZ UK
- Centre for Pathology, Imperial College London, London, SW7 2AZ UK
| | - Paul M. W. French
- Photonics Group, Department of Physics, Imperial College London, London, SW7 2AZ UK
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8
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Correction Approach for Delta Function Convolution Model Fitting of Fluorescence Decay Data in the Case of a Monoexponential Reference Fluorophore. J Fluoresc 2015; 25:1169-82. [PMID: 26063535 PMCID: PMC4596904 DOI: 10.1007/s10895-015-1583-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Accepted: 05/04/2015] [Indexed: 01/11/2023]
Abstract
A correction is proposed to the Delta function convolution method (DFCM) for fitting a multiexponential decay model to time-resolved fluorescence decay data using a monoexponential reference fluorophore. A theoretical analysis of the discretised DFCM multiexponential decay function shows the presence an extra exponential decay term with the same lifetime as the reference fluorophore that we denote as the residual reference component. This extra decay component arises as a result of the discretised convolution of one of the two terms in the modified model function required by the DFCM. The effect of the residual reference component becomes more pronounced when the fluorescence lifetime of the reference is longer than all of the individual components of the specimen under inspection and when the temporal sampling interval is not negligible compared to the quantity (τR (-1) - τ(-1))(-1), where τR and τ are the fluorescence lifetimes of the reference and the specimen respectively. It is shown that the unwanted residual reference component results in systematic errors when fitting simulated data and that these errors are not present when the proposed correction is applied. The correction is also verified using real data obtained from experiment.
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9
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Lagarto J, Dyer BT, Talbot C, Sikkel MB, Peters NS, French PMW, Lyon AR, Dunsby C. Application of time-resolved autofluorescence to label-free in vivo optical mapping of changes in tissue matrix and metabolism associated with myocardial infarction and heart failure. BIOMEDICAL OPTICS EXPRESS 2015; 6:324-46. [PMID: 25780727 PMCID: PMC4354591 DOI: 10.1364/boe.6.000324] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/17/2014] [Accepted: 10/21/2014] [Indexed: 05/03/2023]
Abstract
We investigate the potential of an instrument combining time-resolved spectrofluorometry and diffuse reflectance spectroscopy to measure structural and metabolic changes in cardiac tissue in vivo in a 16 week post-myocardial infarction heart failure model in rats. In the scar region, we observed changes in the fluorescence signal that can be explained by increased collagen content, which is in good agreement with histology. In areas remote from the scar tissue, we measured changes in the fluorescence signal (p < 0.001) that cannot be explained by differences in collagen content and we attribute this to altered metabolism within the myocardium. A linear discriminant analysis algorithm was applied to the measurements to predict the tissue disease state. When we combine all measurements, our results reveal high diagnostic accuracy in the infarcted area (100%) and border zone (94.44%) as well as in remote regions from the scar (> 77%). Overall, our results demonstrate the potential of our instrument to characterize structural and metabolic changes in a failing heart in vivo without using exogenous labels.
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Affiliation(s)
- João Lagarto
- Photonics Group, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ
UK
- Authors contributed equally to this work
| | - Benjamin T. Dyer
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN
UK
- Authors contributed equally to this work
| | - Clifford Talbot
- Photonics Group, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ
UK
| | - Markus B. Sikkel
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN
UK
| | - Nicholas S. Peters
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN
UK
| | - Paul M. W. French
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN
UK
| | - Alexander R. Lyon
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London, W12 0NN
UK
- Authors contributed equally to this work
| | - Chris Dunsby
- Photonics Group, Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ
UK
- Authors contributed equally to this work
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Sparks H, Warren S, Guedes J, Yoshida N, Charn TC, Guerra N, Tatla T, Dunsby C, French P. A flexible wide-field FLIM endoscope utilising blue excitation light for label-free contrast of tissue. JOURNAL OF BIOPHOTONICS 2015; 8:168-78. [PMID: 24573953 PMCID: PMC4737404 DOI: 10.1002/jbio.201300203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 01/20/2014] [Accepted: 02/06/2014] [Indexed: 05/26/2023]
Abstract
Fluorescence lifetime imaging (FLIM) has previously been shown to provide contrast between normal and diseased tissue. Here we present progress towards clinical and preclinical FLIM endoscopy of tissue autofluorescence, demonstrating a flexible wide-field endoscope that utilised a low average power blue picosecond laser diode excitation source and was able to acquire ∼mm-scale spatial maps of autofluorescence lifetimes from fresh ex vivo diseased human larynx biopsies in ∼8 seconds using an average excitation power of ∼0.5 mW at the specimen. To illustrate its potential for FLIM at higher acquisition rates, a higher power mode-locked frequency doubled Ti:Sapphire laser was used to demonstrate FLIM of ex vivo mouse bowel at up to 2.5 Hz using 10 mW of average excitation power at the specimen.
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Affiliation(s)
- Hugh Sparks
- Photonics Group, Physics Department, Imperial College London, London SW7 2AZ, UK.
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11
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Robinson T, Valluri P, Kennedy G, Sardini A, Dunsby C, Neil MAA, Baldwin GS, French PMW, de Mello AJ. Analysis of DNA binding and nucleotide flipping kinetics using two-color two-photon fluorescence lifetime imaging microscopy. Anal Chem 2014; 86:10732-40. [PMID: 25303623 DOI: 10.1021/ac502732s] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Uracil DNA glycosylase plays a key role in DNA maintenance via base excision repair. Its role is to bind to DNA, locate unwanted uracil, and remove it using a base flipping mechanism. To date, kinetic analysis of this complex process has been achieved using stopped-flow analysis but, due to limitations in instrumental dead-times, discrimination of the "binding" and "base flipping" steps is compromised. Herein we present a novel approach for analyzing base flipping using a microfluidic mixer and two-color two-photon (2c2p) fluorescence lifetime imaging microscopy (FLIM). We demonstrate that 2c2p FLIM can simultaneously monitor binding and base flipping kinetics within the continuous flow microfluidic mixer, with results showing good agreement with computational fluid dynamics simulations.
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Affiliation(s)
- Tom Robinson
- Institute of Chemical Biology, Department of Chemistry, Imperial College London , London SW7 2AZ, U.K
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12
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Manning HB, Nickdel MB, Yamamoto K, Lagarto JL, Kelly DJ, Talbot CB, Kennedy G, Dudhia J, Lever J, Dunsby C, French P, Itoh Y. Detection of cartilage matrix degradation by autofluorescence lifetime. Matrix Biol 2013; 32:32-8. [DOI: 10.1016/j.matbio.2012.11.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 09/18/2012] [Accepted: 11/29/2012] [Indexed: 12/01/2022]
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13
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Laine R, Stuckey DW, Manning H, Warren SC, Kennedy G, Carling D, Dunsby C, Sardini A, French PMW. Fluorescence lifetime readouts of Troponin-C-based calcium FRET sensors: a quantitative comparison of CFP and mTFP1 as donor fluorophores. PLoS One 2012; 7:e49200. [PMID: 23152874 PMCID: PMC3494685 DOI: 10.1371/journal.pone.0049200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 10/08/2012] [Indexed: 11/23/2022] Open
Abstract
We have compared the performance of two Troponin-C-based calcium FRET sensors using fluorescence lifetime read-outs. The first sensor, TN-L15, consists of a Troponin-C fragment inserted between CFP and Citrine while the second sensor, called mTFP-TnC-Cit, was realized by replacing CFP in TN-L15 with monomeric Teal Fluorescent Protein (mTFP1). Using cytosol preparations of transiently transfected mammalian cells, we have measured the fluorescence decay profiles of these sensors at controlled concentrations of calcium using time-correlated single photon counting. These data were fitted to discrete exponential decay models using global analysis to determine the FRET efficiency, fraction of donor molecules undergoing FRET and calcium affinity of these sensors. We have also studied the decay profiles of the donor fluorescent proteins alone and determined the sensitivity of the donor lifetime to temperature and emission wavelength. Live-cell fluorescence lifetime imaging (FLIM) of HEK293T cells expressing each of these sensors was also undertaken. We confirmed that donor fluorescence of mTFP-TnC-Cit fits well to a two-component decay model, while the TN-L15 lifetime data was best fitted to a constrained four-component model, which was supported by phasor analysis of the measured lifetime data. If the constrained global fitting is employed, the TN-L15 sensor can provide a larger dynamic range of lifetime readout than the mTFP-TnC-Cit sensor but the CFP donor is significantly more sensitive to changes in temperature and emission wavelength compared to mTFP and, while the mTFP-TnC-Cit solution phase data broadly agreed with measurements in live cells, this was not the case for the TN-L15 sensor. Our titration experiment also indicates that a similar precision in determination of calcium concentration can be achieved with both FRET biosensors when fitting a single exponential donor fluorescence decay model to the fluorescence decay profiles. We therefore suggest that mTFP-based probes are more suitable for FLIM experiments than CFP-based probes.
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Affiliation(s)
- Romain Laine
- Institute of Chemical Biology (ICB), Imperial College of Science, Technology & Medicine, Institute of Chemical Biology (ICB), London, England
- Photonics Group, Blackett Lab, Imperial College of Science, Technology & Medicine, London, England
- Medical Research Council (MRC) Clinical Sciences Centre, Imperial College of Science, Technology & Medicine, London, England
- * E-mail:
| | - Daniel W. Stuckey
- Medical Research Council (MRC) Clinical Sciences Centre, Imperial College of Science, Technology & Medicine, London, England
| | - Hugh Manning
- Photonics Group, Blackett Lab, Imperial College of Science, Technology & Medicine, London, England
| | - Sean C. Warren
- Photonics Group, Blackett Lab, Imperial College of Science, Technology & Medicine, London, England
| | - Gordon Kennedy
- Photonics Group, Blackett Lab, Imperial College of Science, Technology & Medicine, London, England
| | - David Carling
- Medical Research Council (MRC) Clinical Sciences Centre, Imperial College of Science, Technology & Medicine, London, England
| | - Chris Dunsby
- Photonics Group, Blackett Lab, Imperial College of Science, Technology & Medicine, London, England
| | - Alessandro Sardini
- Medical Research Council (MRC) Clinical Sciences Centre, Imperial College of Science, Technology & Medicine, London, England
| | - Paul M. W. French
- Photonics Group, Blackett Lab, Imperial College of Science, Technology & Medicine, London, England
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14
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McGinty J, Stuckey DW, Soloviev VY, Laine R, Wylezinska-Arridge M, Wells DJ, Arridge SR, French PMW, Hajnal JV, Sardini A. In vivo fluorescence lifetime tomography of a FRET probe expressed in mouse. BIOMEDICAL OPTICS EXPRESS 2011; 2:1907-17. [PMID: 21750768 PMCID: PMC3130577 DOI: 10.1364/boe.2.001907] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 06/06/2011] [Accepted: 06/10/2011] [Indexed: 05/06/2023]
Abstract
Förster resonance energy transfer (FRET) is a powerful biological tool for reading out cell signaling processes. In vivo use of FRET is challenging because of the scattering properties of bulk tissue. By combining diffuse fluorescence tomography with fluorescence lifetime imaging (FLIM), implemented using wide-field time-gated detection of fluorescence excited by ultrashort laser pulses in a tomographic imaging system and applying inverse scattering algorithms, we can reconstruct the three dimensional spatial localization of fluorescence quantum efficiency and lifetime. We demonstrate in vivo spatial mapping of FRET between genetically expressed fluorescent proteins in live mice read out using FLIM. Following transfection by electroporation, mouse hind leg muscles were imaged in vivo and the emission of free donor (eGFP) in the presence of free acceptor (mCherry) could be clearly distinguished from the fluorescence of the donor when directly linked to the acceptor in a tandem (eGFP-mCherry) FRET construct.
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Affiliation(s)
- James McGinty
- Photonics Group, Blackett Laboratory, Imperial College London, London SW7 2BW, UK
- These authors contributed equally to this work
| | - Daniel W. Stuckey
- MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, London W12 0NN, UK
- These authors contributed equally to this work
| | - Vadim Y. Soloviev
- Department of Computer Science, University College London, London WC1E 6BT, UK
| | - Romain Laine
- Photonics Group, Blackett Laboratory, Imperial College London, London SW7 2BW, UK
| | | | - Dominic J. Wells
- Department of Veterinary Basic Sciences, The Royal Veterinary College, London NW1 0TU, UK
| | - Simon R. Arridge
- Department of Computer Science, University College London, London WC1E 6BT, UK
| | - Paul M. W. French
- Photonics Group, Blackett Laboratory, Imperial College London, London SW7 2BW, UK
| | - Joseph V. Hajnal
- MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, London W12 0NN, UK
| | - Alessandro Sardini
- MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, London W12 0NN, UK
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15
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Kumar S, Alibhai D, Margineanu A, Laine R, Kennedy G, McGinty J, Warren S, Kelly D, Alexandrov Y, Munro I, Talbot C, Stuckey DW, Kimberly C, Viellerobe B, Lacombe F, Lam EWF, Taylor H, Dallman MJ, Stamp G, Murray EJ, Stuhmeier F, Sardini A, Katan M, Elson DS, Neil MAA, Dunsby C, French PMW. FLIM FRET technology for drug discovery: automated multiwell-plate high-content analysis, multiplexed readouts and application in situ. Chemphyschem 2011; 12:609-26. [PMID: 21337485 PMCID: PMC3084521 DOI: 10.1002/cphc.201000874] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 12/07/2010] [Indexed: 11/10/2022]
Abstract
A fluorescence lifetime imaging (FLIM) technology platform intended to read out changes in Förster resonance energy transfer (FRET) efficiency is presented for the study of protein interactions across the drug-discovery pipeline. FLIM provides a robust, inherently ratiometric imaging modality for drug discovery that could allow the same sensor constructs to be translated from automated cell-based assays through small transparent organisms such as zebrafish to mammals. To this end, an automated FLIM multiwell-plate reader is described for high content analysis of fixed and live cells, tomographic FLIM in zebrafish and FLIM FRET of live cells via confocal endomicroscopy. For cell-based assays, an exemplar application reading out protein aggregation using FLIM FRET is presented, and the potential for multiple simultaneous FLIM (FRET) readouts in microscopy is illustrated.
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Affiliation(s)
- Sunil Kumar
- Photonics Group, Department of Physics, Imperial College London, London SW7 2AZ, UK.
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16
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Esposito A, Bader AN, Schlachter SC, van den Heuvel DJ, Schierle GSK, Venkitaraman AR, Kaminski CF, Gerritsen HC. Design and application of a confocal microscope for spectrally resolved anisotropy imaging. OPTICS EXPRESS 2011; 19:2546-2555. [PMID: 21369074 DOI: 10.1364/oe.19.002546] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Biophysical imaging tools exploit several properties of fluorescence to map cellular biochemistry. However, the engineering of a cost-effective and user-friendly detection system for sensing the diverse properties of fluorescence is a difficult challenge. Here, we present a novel architecture for a spectrograph that permits integrated characterization of excitation, emission and fluorescence anisotropy spectra in a quantitative and efficient manner. This sensing platform achieves excellent versatility of use at comparatively low costs. We demonstrate the novel optical design with example images of plant cells and of mammalian cells expressing fluorescent proteins undergoing energy transfer.
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Affiliation(s)
- Alessandro Esposito
- The Medical Research Council Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK.
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17
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Membrane environment exerts an important influence on rac-mediated activation of phospholipase Cγ2. Mol Cell Biol 2011; 31:1240-51. [PMID: 21245382 DOI: 10.1128/mcb.01408-10] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We performed analyses of the molecular mechanisms involved in the regulation of phospholipase Cγ2 (PLCγ2). We identified several regions in the PLCγ-specific array, γSA, that contribute to autoinhibition in the basal state by occlusion of the catalytic domain. While the activation of PLCγ2 by Rac2 requires stable translocation to the membrane, the removal of the domains required for membrane translocation in the context of an enzyme with impaired autoinhibition generated constitutive, highly active PLC in cells. We further tested the possibility that the interaction of PLCγ2 with its activator protein Rac2 was sufficient for activation through the release of autoinhibition. However, we found that Rac2 binding in the absence of lipid surfaces was not able to activate PLCγ2. Together with other observations, these data suggest that an important consequence of Rac2 binding and translocation to the membrane is that membrane proximity, on its own or together with Rac2, has a role in the release of autoinhibition, resulting in interfacial activation.
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18
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Grippon S, Zhao Q, Robinson T, Marshall JJT, O'Neill RJ, Manning H, Kennedy G, Dunsby C, Neil M, Halford SE, French PMW, Baldwin GS. Differential modes of DNA binding by mismatch uracil DNA glycosylase from Escherichia coli: implications for abasic lesion processing and enzyme communication in the base excision repair pathway. Nucleic Acids Res 2010; 39:2593-603. [PMID: 21112870 PMCID: PMC3074160 DOI: 10.1093/nar/gkq913] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Mismatch uracil DNA glycosylase (Mug) from Escherichia coli is an initiating enzyme in the base-excision repair pathway. As with other DNA glycosylases, the abasic product is potentially more harmful than the initial lesion. Since Mug is known to bind its product tightly, inhibiting enzyme turnover, understanding how Mug binds DNA is of significance when considering how Mug interacts with downstream enzymes in the base-excision repair pathway. We have demonstrated differential binding modes of Mug between its substrate and abasic DNA product using both band shift and fluorescence anisotropy assays. Mug binds its product cooperatively, and a stoichiometric analysis of DNA binding, catalytic activity and salt-dependence indicates that dimer formation is of functional significance in both catalytic activity and product binding. This is the first report of cooperativity in the uracil DNA glycosylase superfamily of enzymes, and forms the basis of product inhibition in Mug. It therefore provides a new perspective on abasic site protection and the findings are discussed in the context of downstream lesion processing and enzyme communication in the base excision repair pathway.
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Affiliation(s)
- Seden Grippon
- Division of Molecular Biosciences, Sir Alexander Fleming Building, Chemical Biology Centre, Imperial College London, South Kensington, London, SW7 2AZ, UK
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19
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Ushakov DS, Caorsi V, Ibanez-Garcia D, Manning HB, Konitsiotis AD, West TG, Dunsby C, French PM, Ferenczi MA. Response of rigor cross-bridges to stretch detected by fluorescence lifetime imaging microscopy of myosin essential light chain in skeletal muscle fibers. J Biol Chem 2010; 286:842-50. [PMID: 21056977 DOI: 10.1074/jbc.m110.149526] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We applied fluorescence lifetime imaging microscopy to map the microenvironment of the myosin essential light chain (ELC) in permeabilized skeletal muscle fibers. Four ELC mutants containing a single cysteine residue at different positions in the C-terminal half of the protein (ELC-127, ELC-142, ELC-160, and ELC-180) were generated by site-directed mutagenesis, labeled with 7-diethylamino-3-((((2-iodoacetamido)ethyl)amino)carbonyl)coumarin, and introduced into permeabilized rabbit psoas fibers. Binding to the myosin heavy chain was associated with a large conformational change in the ELC. When the fibers were moved from relaxation to rigor, the fluorescence lifetime increased for all label positions. However, when 1% stretch was applied to the rigor fibers, the lifetime decreased for ELC-127 and ELC-180 but did not change for ELC-142 and ELC-160. The differential change of fluorescence lifetime demonstrates the shift in position of the C-terminal domain of ELC with respect to the heavy chain and reveals specific locations in the lever arm region sensitive to the mechanical strain propagating from the actin-binding site to the lever arm.
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Affiliation(s)
- Dmitry S Ushakov
- National Heart and Lung Institute, Imperial College London, London SW7 2AZ, United Kingdom.
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20
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Owen DM, Gaus K. Optimized time-gated generalized polarization imaging of Laurdan and di-4-ANEPPDHQ for membrane order image contrast enhancement. Microsc Res Tech 2010; 73:618-22. [PMID: 19937746 DOI: 10.1002/jemt.20801] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The membrane dyes Laurdan and di-4-ANEPPDHQ can be used to image membrane order due to a spectral blue-shift in the fluorescence emission between the liquid-ordered and liquid-disordered phases. These images typically take the form of a normalized intensity ratio image known as a generalized polarization (GP) plot. Here, we exploit the known excited state photophysics and time-resolved data acquisition via time-correlated single-photon counting (TCSPC) to demonstrate GP contrast enhancement for these two probes of 7 and 31%, respectively. This improvement in image contrast enhancement will be invaluable when studying the role of lipid rafts in fixed and live cell systems.
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Affiliation(s)
- Dylan M Owen
- Centre for Vascular Research, University of New South Wales, Sydney, Australia.
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21
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Kennedy GT, Manning HB, Elson DS, Neil MAA, Stamp GW, Viellerobe B, Lacombe F, Dunsby C, French PMW. A fluorescence lifetime imaging scanning confocal endomicroscope. JOURNAL OF BIOPHOTONICS 2010; 3:103-7. [PMID: 19787682 DOI: 10.1002/jbio.200910065] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We describe a fluorescence lifetime imaging endomicroscope employing a fibre bundle probe and time correlated single photon counting. Preliminary images of stained pollen grains, eGFP-labelled cells exhibiting Förster resonant energy transfer and tissue autofluorescence are presented.
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22
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Thoss A. Biophotonics--today and tomorrow. JOURNAL OF BIOPHOTONICS 2008; 1:435-436. [PMID: 19343667 DOI: 10.1002/jbio.200810521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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