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Serafino MJ, Jo JA. Direct frequency domain fluorescence lifetime imaging using simultaneous ultraviolet and visible excitation. BIOMEDICAL OPTICS EXPRESS 2023; 14:1608-1625. [PMID: 37078041 PMCID: PMC10110304 DOI: 10.1364/boe.480287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 03/16/2023] [Accepted: 03/17/2023] [Indexed: 05/03/2023]
Abstract
Due to the complexity, limited practicality, and cost of conventional fluorescence lifetime imaging/microscopy (FLIM) instrumentation, FLIM adoption has been mostly limited to academic settings. We present a novel point scanning frequency-domain (FD) FLIM instrumentation design capable of simultaneous multi-wavelength excitation, simultaneous multispectral detection, and sub-nanosecond to nanosecond fluorescence lifetime estimation. Fluorescence excitation is implemented using intensity-modulated CW diode lasers that are available in a selection of wavelengths spanning the UV-VI-NIR range (375-1064 nm). Digital laser intensity modulation was adopted to enable simultaneous frequency interrogation at the fundamental frequency and corresponding harmonics. Time-resolved fluorescence detection is implemented using low-cost, fixed-gain, narrow bandwidth (100 MHz) avalanche photodiodes, thus, enabling cost-effective fluorescence lifetime measurements at multiple emission spectral bands simultaneously. Synchronized laser modulation and fluorescence signal digitization (250 MHz) is implemented using a common field-programmable gate array (FPGA). This synchronization reduces temporal jitter, which simplifies instrumentation, system calibration, and data processing. The FPGA also allows for the implementation of the real-time processing of the fluorescence emission phase and modulation at up to 13 modulation frequencies (processing rate matching the sampling rate of 250 MHz). Rigorous validation experiments have demonstrated the capabilities of this novel FD-FLIM implementation to accurately measure fluorescence lifetimes in the range of 0.5-12 ns. In vivo endogenous, dual-excitation (375nm/445nm), multispectral (four bands) FD-FLIM imaging of human skin and oral mucosa at 12.5 kHz pixel rate and room-light conditions was also successfully demonstrated. This versatile, simple, compact, and cost-effective FD-FLIM implementation will facilitate the clinical translation of FLIM imaging and microscopy.
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Affiliation(s)
- Michael J Serafino
- Department of Electrical and Computer Engineering, University of Oklahoma, Stephenson Research and Technology Center, Suite 1108, 101 David L Boren Blvd, Norman, OK 73072, USA
| | - Javier A Jo
- Department of Electrical and Computer Engineering, University of Oklahoma, Stephenson Research and Technology Center, Suite 1108, 101 David L Boren Blvd, Norman, OK 73072, USA
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2
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Acuña-Rodriguez JP, Mena-Vega JP, Argüello-Miranda O. Live-cell fluorescence spectral imaging as a data science challenge. Biophys Rev 2022; 14:579-597. [PMID: 35528031 PMCID: PMC9043069 DOI: 10.1007/s12551-022-00941-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 03/09/2022] [Indexed: 12/13/2022] Open
Abstract
Live-cell fluorescence spectral imaging is an evolving modality of microscopy that uses specific properties of fluorophores, such as excitation or emission spectra, to detect multiple molecules and structures in intact cells. The main challenge of analyzing live-cell fluorescence spectral imaging data is the precise quantification of fluorescent molecules despite the weak signals and high noise found when imaging living cells under non-phototoxic conditions. Beyond the optimization of fluorophores and microscopy setups, quantifying multiple fluorophores requires algorithms that separate or unmix the contributions of the numerous fluorescent signals recorded at the single pixel level. This review aims to provide both the experimental scientist and the data analyst with a straightforward description of the evolution of spectral unmixing algorithms for fluorescence live-cell imaging. We show how the initial systems of linear equations used to determine the concentration of fluorophores in a pixel progressively evolved into matrix factorization, clustering, and deep learning approaches. We outline potential future trends on combining fluorescence spectral imaging with label-free detection methods, fluorescence lifetime imaging, and deep learning image analysis.
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Affiliation(s)
- Jessy Pamela Acuña-Rodriguez
- grid.412889.e0000 0004 1937 0706Center for Geophysical Research (CIGEFI), University of Costa Rica, San Pedro, San José Costa Rica
- grid.412889.e0000 0004 1937 0706School of Physics, University of Costa Rica, 2060 San Pedro, San José Costa Rica
| | - Jean Paul Mena-Vega
- grid.412889.e0000 0004 1937 0706School of Physics, University of Costa Rica, 2060 San Pedro, San José Costa Rica
| | - Orlando Argüello-Miranda
- grid.40803.3f0000 0001 2173 6074Department of Plant and Microbial Biology, North Carolina State University, 112 DERIEUX PLACE, Raleigh, NC 27695-7612 USA
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3
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Dorozynska K, Ek S, Kornienko V, Andersson D, Andersson A, Ehn A, Kristensson E. Snapshot multicolor fluorescence imaging using double multiplexing of excitation and emission on a single detector. Sci Rep 2021; 11:20454. [PMID: 34650144 PMCID: PMC8517015 DOI: 10.1038/s41598-021-99670-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 09/27/2021] [Indexed: 12/02/2022] Open
Abstract
Fluorescence-based multispectral imaging of rapidly moving or dynamic samples requires both fast two-dimensional data acquisition as well as sufficient spectral sensitivity for species separation. As the number of fluorophores in the experiment increases, meeting both these requirements becomes technically challenging. Although several solutions for fast imaging of multiple fluorophores exist, they all have one main restriction; they rely solely on spectrally resolving either the excitation- or the emission characteristics of the fluorophores. This inability directly limits how many fluorophores existing methods can simultaneously distinguish. Here we present a snapshot multispectral imaging approach that not only senses the excitation and emission characteristics of the probed fluorophores but also all cross term combinations of excitation and emission. To the best of the authors’ knowledge, this is the only snapshot multispectral imaging method that has this ability, allowing us to even sense and differentiate between light of equal wavelengths emitted from the same fluorescing species but where the signal components stem from different excitation sources. The current implementation of the technique allows us to simultaneously gather 24 different spectral images on a single detector, from which we demonstrate the ability to visualize and distinguish up to nine fluorophores within the visible wavelength range.
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Affiliation(s)
| | - Simon Ek
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden
| | - Vassily Kornienko
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden
| | - David Andersson
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden
| | | | - Andreas Ehn
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden
| | - Elias Kristensson
- Department of Combustion Physics, Lund University, 22363, Lund, Sweden.
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4
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Fourier Multiplexed Fluorescence Lifetime Imaging. Methods Mol Biol 2021. [PMID: 34331285 DOI: 10.1007/978-1-0716-1593-5_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Fluorescence lifetime imaging microscopy (FLIM) is a widely used functional imaging method in bioscience. Fourier multiplexed FLIM (FmFLIM), a frequency-domain lifetime measurement method, explores the principle of Fourier (frequency) multiplexing to achieve parallel lifetime detection on multiple fluorescence labels. Combining FmFLIM with a confocal scanning microscope allows multiplexed 3D lifetime imaging of cells and tissues. FmFLIM can also be integrated with the scanning laser tomography imaging method to perform 3D multiplex lifetime imaging of whole embryos and thick tissues.
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5
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Thiele JC, Helmerich DA, Oleksiievets N, Tsukanov R, Butkevich E, Sauer M, Nevskyi O, Enderlein J. Confocal Fluorescence-Lifetime Single-Molecule Localization Microscopy. ACS NANO 2020; 14:14190-14200. [PMID: 33035050 DOI: 10.1021/acsnano.0c07322] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Fluorescence lifetime imaging microscopy is an important technique that adds another dimension to intensity and color acquired by conventional microscopy. In particular, it allows for multiplexing fluorescent labels that have otherwise similar spectral properties. Currently, the only super-resolution technique that is capable of recording super-resolved images with lifetime information is stimulated emission depletion microscopy. In contrast, all single-molecule localization microscopy (SMLM) techniques that employ wide-field cameras completely lack the lifetime dimension. Here, we combine fluorescence-lifetime confocal laser-scanning microscopy with SMLM for realizing single-molecule localization-based fluorescence-lifetime super-resolution imaging. Besides yielding images with a spatial resolution much beyond the diffraction limit, it determines the fluorescence lifetime of all localized molecules. We validate our technique by applying it to direct stochastic optical reconstruction microscopy and points accumulation for imaging in nanoscale topography imaging of fixed cells, and we demonstrate its multiplexing capability on samples with two different labels that differ only by fluorescence lifetime but not by their spectral properties.
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Affiliation(s)
- Jan Christoph Thiele
- III. Institute of Physics-Biophysics, Georg August University, Göttingen 37077, Germany
| | - Dominic A Helmerich
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Nazar Oleksiievets
- III. Institute of Physics-Biophysics, Georg August University, Göttingen 37077, Germany
| | - Roman Tsukanov
- III. Institute of Physics-Biophysics, Georg August University, Göttingen 37077, Germany
| | - Eugenia Butkevich
- III. Institute of Physics-Biophysics, Georg August University, Göttingen 37077, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Oleksii Nevskyi
- III. Institute of Physics-Biophysics, Georg August University, Göttingen 37077, Germany
| | - Jörg Enderlein
- III. Institute of Physics-Biophysics, Georg August University, Göttingen 37077, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Georg August University, Göttingen 37077, Germany
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6
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Gigapixel confocal imaging using a massively parallel optical probe array with single directional infinite scanning. Sci Rep 2020; 10:7658. [PMID: 32376894 PMCID: PMC7203176 DOI: 10.1038/s41598-020-64602-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 04/20/2020] [Indexed: 11/08/2022] Open
Abstract
Here we demonstrate high-throughput gigapixel confocal imaging using a massively parallel optical probe array with single directional infinite scanning. For implementation of the single directional infinite scan with high lateral resolution, a parallelogram array micro-objective lens module, composed of two wafer-level microlens arrays, is proposed to generate a massively parallel optical probe array for integration into the confocal imaging system, including an objective-side telecentric relay lens with a low-magnification. To test the feasibility of the proposed system with single directional infinite scanning, we designed and constructed a confocal imaging system using a parallelogram array of multi-optical probes with a massively parallel array size of 200 × 140. The constructed system provides a full width-half maximum lateral resolution of 1.55 μm, as measured by the knife-edge detection method, and a field-of-view width of 28.0 mm with a sampling interval of 1 μm/pixel.
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7
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Jia X, Zhou W, Huang F, Guo H, Hu J. Monitoring algorithm of tilt angle based on sub-block plane fitting for high-resolution imaging. APPLIED OPTICS 2019; 58:5873-5882. [PMID: 31503894 DOI: 10.1364/ao.58.005873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 06/26/2019] [Indexed: 06/10/2023]
Abstract
The limitation of mechanical structure and misoperations can result in a small tilt angle formed by the sample and the focal plane, which will decrease the resolution of the imaging system. Moreover, the small tilt angle is difficult to be observed. In order to solve this problem, a monitoring algorithm of tilt angle based on sub-block plane fitting for high-resolution imaging systems has been proposed, which is used to measure the initial angle of most 2D samples before imaging and assist users to determine the tilt degree of the sample. Experiments demonstrate that the proposed method can measure the tilt angle with a high measurement precision of 0.007° and a low residual tilt angle of 0.004°, indicating that the algorithm has high measurement precision and stability. Further results show that the quality of the image will be improved by 20%-27% when the tilt angle is 0.3056°, which means that the small degree of tilt of the sample can seriously damage the image quality. Therefore, the study of tilt angle measurement has great significance for high-resolution imaging systems.
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9
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Excitation-multiplexed multicolor superresolution imaging with fm-STORM and fm-DNA-PAINT. Proc Natl Acad Sci U S A 2018; 115:12991-12996. [PMID: 30509979 DOI: 10.1073/pnas.1804725115] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Recent advancements in single-molecule-based superresolution microscopy have made it possible to visualize biological structures with unprecedented spatial resolution. Determining the spatial coorganization of these structures within cells under physiological and pathological conditions is an important biological goal. This goal has been stymied by the current limitations of carrying out superresolution microscopy in multiple colors. Here, we develop an approach for simultaneous multicolor superresolution imaging which relies solely on fluorophore excitation, rather than fluorescence emission properties. By modulating the intensity of the excitation lasers at different frequencies, we show that the color channel can be determined based on the fluorophore's response to the modulated excitation. We use this frequency multiplexing to reduce the image acquisition time of multicolor superresolution DNA-PAINT while maintaining all its advantages: minimal color cross-talk, minimal photobleaching, maximal signal throughput, ability to maintain the fluorophore density per imaged color, and ability to use the full camera field of view. We refer to this imaging modality as "frequency multiplexed DNA-PAINT," or fm-DNA-PAINT for short. We also show that frequency multiplexing is fully compatible with STORM superresolution imaging, which we term fm-STORM. Unlike fm-DNA-PAINT, fm-STORM is prone to color cross-talk. To overcome this caveat, we further develop a machine-learning algorithm to correct for color cross-talk with more than 95% accuracy, without the need for prior information about the imaged structure.
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10
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Garbacik ET, Sanz-Paz M, Borgman KJE, Campelo F, Garcia-Parajo MF. Frequency-Encoded Multicolor Fluorescence Imaging with Single-Photon-Counting Color-Blind Detection. Biophys J 2018; 115:725-736. [PMID: 30037496 PMCID: PMC6104530 DOI: 10.1016/j.bpj.2018.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/25/2018] [Accepted: 07/09/2018] [Indexed: 02/06/2023] Open
Abstract
Standard fluorescence microscopy relies on filter-based detection of emitted photons after fluorophore excitation at the appropriate wavelength. Although of enormous utility to the biological community, the implementation of approaches for simultaneous multicolor fluorescence imaging is commonly challenged by the large spectral overlap between different fluorophores. Here, we describe an alternative multicolor fluorescence imaging methodology that exclusively relies on the absorption spectra of the fluorophores instead of their fluorescence emissions. The method is based on multiplexing optical excitation signals in the frequency domain and using single color-blind detection. Because the spectral information is fully encoded during excitation, the method requires minimal spectral filtering on detection. This enables the simultaneous identification of multiple color channels in a single measurement with only one color-blind detector. We demonstrate simultaneous three-color confocal imaging of individual molecules and of four-target imaging on cells with excellent discrimination. Moreover, we have implemented a non-negative matrix factorization algorithm for spectral unmixing to extend the number of color targets that can be discriminated in a single measurement. Using this algorithm, we resolve six spectrally and spatially overlapping fluorophores on fixed cells using four excitation wavelengths. The methodology is fully compatible with live imaging of biological samples and can be easily extended to other imaging modalities, including super-resolution microscopy, making simultaneous multicolor imaging more accessible to the biological research community.
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Affiliation(s)
- Erik T Garbacik
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Maria Sanz-Paz
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Kyra J E Borgman
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Felix Campelo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Maria F Garcia-Parajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain; ICREA, Barcelona, Spain.
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11
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Butkevich AN, Lukinavičius G, D’Este E, Hell SW. Cell-Permeant Large Stokes Shift Dyes for Transfection-Free Multicolor Nanoscopy. J Am Chem Soc 2017; 139:12378-12381. [DOI: 10.1021/jacs.7b06412] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Alexey N. Butkevich
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Gražvydas Lukinavičius
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Elisa D’Este
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Stefan W. Hell
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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12
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Xu D, Zhou W, Peng L. Cellular resolution multiplexed FLIM tomography with dual-color Bessel beam. BIOMEDICAL OPTICS EXPRESS 2017; 8:570-578. [PMID: 28270968 PMCID: PMC5330577 DOI: 10.1364/boe.8.000570] [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: 09/14/2016] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 05/23/2023]
Abstract
Fourier multiplexed FLIM (FmFLIM) tomography enables multiplexed 3D lifetime imaging of whole embryos. In our previous FmFLIM system, the spatial resolution was limited to 25 μm because of the trade-off between the spatial resolution and the imaging depth. In order to achieve cellular resolution imaging of thick specimens, we built a tomography system with dual-color Bessel beam. In combination with FmFLIM, the Bessel FmFLIM tomography system can perform parallel 3D lifetime imaging on multiple excitation-emission channels at a cellular resolution of 2.8 μm. The image capability of the Bessel FmFLIM tomography system was demonstrated by 3D lifetime imaging of dual-labeled transgenic zebrafish embryos.
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Affiliation(s)
- Dongli Xu
- College of Optical Sciences, the University of Arizona, 1630 East University Blvd., Tucson, AZ 85721, USA
| | - Weibin Zhou
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, MI 48109, USA
| | - Leilei Peng
- College of Optical Sciences, the University of Arizona, 1630 East University Blvd., Tucson, AZ 85721, USA
- Department of Molecular and Cell Biology, University of Arizona, 1007 E. Lowell Street, Tucson. AZ 85721, USA
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13
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Pian Q, Yao R, Sinsuebphon N, Intes X. Compressive hyperspectral time-resolved wide-field fluorescence lifetime imaging. NATURE PHOTONICS 2017; 11:411-414. [PMID: 29242714 PMCID: PMC5726531 DOI: 10.1038/nphoton.2017.82] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/03/2017] [Indexed: 05/18/2023]
Abstract
Spectrally resolved fluorescence lifetime imaging1-3 and spatial multiplexing1,4,5 have offered information content and collection-efficiency boosts in microscopy, but efficient implementations for macroscopic applications are still lacking. An imaging platform based on time-resolved structured light and hyperspectral single-pixel detection has been developed to perform quantitative macroscopic fluorescence lifetime imaging (MFLI) over a large field of view (FOV) and multiple spectral bands simultaneously. The system makes use of three digital micromirror device (DMD)-based spatial light modulators (SLMs) to generate spatial optical bases and reconstruct N by N images over 16 spectral channels with a time-resolved capability (~40 ps temporal resolution) using fewer than N2 optical measurements. We demonstrate the potential of this new imaging platform by quantitatively imaging near-infrared (NIR) Förster resonance energy transfer (FRET) both in vitro and in vivo. The technique is well suited for quantitative hyperspectral lifetime imaging with a high sensitivity and paves the way for many important biomedical applications.
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Affiliation(s)
| | | | | | - Xavier Intes
- Correspondence and requests for materials should be addressed to X.I.
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14
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Yu H, Saleeb R, Dalgarno P, Day-Uei Li D. Estimation of Fluorescence Lifetimes Via Rotational Invariance Techniques. IEEE Trans Biomed Eng 2016; 63:1292-300. [DOI: 10.1109/tbme.2015.2491364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Zhang J, Song F, Lin S, Liu S, Liu Y. Tunable fluorescence lifetime of Eu-PMMA films with plasmonic nanostructures for multiplexing. OPTICS EXPRESS 2016; 24:8228-8236. [PMID: 27137261 DOI: 10.1364/oe.24.008228] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A method to tune fluorescence lifetime of Eu-PMMA films is proposed, which consists of self-assembled gold nanorods on glass substrate covered by Eu-PMMA shell. The fluorescence lifetime is tunable in a wide range, and depends on aspect ratio and mutual distance of gold nanorods. In a single red color emission channel, more than six distinct fluorescence lifetime populations ranging from 356 to 513 μs are obtained. Through theoretical calculation, we attribute tunable fluorescence lifetime to the change of radiative and nonradiative decay rate and density of photon states. In addition, we use these as-prepared Eu-PMMA films for security data storage to demonstrate optical multiplexing applications. The optical multiplexing experiments show an interesting pseudo-information "8" and conceal the real messages "2" and "6".
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16
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Multiplexed 3D FRET imaging in deep tissue of live embryos. Sci Rep 2015; 5:13991. [PMID: 26387920 PMCID: PMC4585674 DOI: 10.1038/srep13991] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 07/29/2015] [Indexed: 02/03/2023] Open
Abstract
Current deep tissue microscopy techniques are mostly restricted to intensity mapping of fluorophores, which significantly limit their applications in investigating biochemical processes in vivo. We present a deep tissue multiplexed functional imaging method that probes multiple Förster resonant energy transfer (FRET) sensors in live embryos with high spatial resolution. The method simultaneously images fluorescence lifetimes in 3D with multiple excitation lasers. Through quantitative analysis of triple-channel intensity and lifetime images, we demonstrated that Ca(2+) and cAMP levels of live embryos expressing dual FRET sensors can be monitored simultaneously at microscopic resolution. The method is compatible with a broad range of FRET sensors currently available for probing various cellular biochemical functions. It opens the door to imaging complex cellular circuitries in whole live organisms.
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17
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Zhao M, Li Y, Peng L. FPGA-based multi-channel fluorescence lifetime analysis of Fourier multiplexed frequency-sweeping lifetime imaging. OPTICS EXPRESS 2014; 22:23073-85. [PMID: 25321778 PMCID: PMC4247184 DOI: 10.1364/oe.22.023073] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 08/26/2014] [Accepted: 08/27/2014] [Indexed: 05/02/2023]
Abstract
We report a fast non-iterative lifetime data analysis method for the Fourier multiplexed frequency-sweeping confocal FLIM (Fm-FLIM) system [Opt. Express 22, 10221 (2014)]. The new method, named R-method, allows fast multi-channel lifetime image analysis in the system's FPGA data processing board. Experimental tests proved that the performance of the R-method is equivalent to that of single-exponential iterative fitting, and its sensitivity is well suited for time-lapse FLIM-FRET imaging of live cells, for example cyclic adenosine monophosphate (cAMP) level imaging with GFP-Epac-mCherry sensors. With the R-method and its FPGA implementation, multi-channel lifetime images can now be generated in real time on the multi-channel frequency-sweeping FLIM system, and live readout of FRET sensors can be performed during time-lapse imaging.
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Affiliation(s)
- Ming Zhao
- College of Optical Sciences, the University of Arizona, 1630 East University Blvd., Tucson, AZ 85721,
USA
| | - Yu Li
- College of Optical Sciences, the University of Arizona, 1630 East University Blvd., Tucson, AZ 85721,
USA
| | - Leilei Peng
- College of Optical Sciences, the University of Arizona, 1630 East University Blvd., Tucson, AZ 85721,
USA
- Molecular and Cellular Biology, the University of Arizona, 1007 E. Lowell St., Tucson, AZ 85721,
USA
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