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Lee M, Kannan S, Muniraj G, Rosa V, Lu WF, Fuh JYH, Sriram G, Cao T. Two-Photon Fluorescence Microscopy and Applications in Angiogenesis and Related Molecular Events. TISSUE ENGINEERING PART B-REVIEWS 2021; 28:926-937. [PMID: 34541887 DOI: 10.1089/ten.teb.2021.0140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The role of angiogenesis in health and disease have gained considerable momentum in recent years. Visualizing angiogenic patterns and associated events of surrounding vascular beds in response to therapeutic and laboratory-grade biomolecules have become a commonplace in regenerative medicine and the biosciences. To aid imaging investigations in angiogenesis, the two-photon excitation fluorescence microscopy (2PEF), or multiphoton fluorescence microscopy is increasingly utilized in scientific investigations. The 2PEF microscope confers several distinct imaging advantages over other fluorescence excitation microscopy techniques - for the observation of in-depth, three-dimensional vascularity in a variety of tissue formats, including fixed tissue specimens and in vivo vasculature in live specimens. Understanding morphological and subcellular changes that occur in cells and tissues during angiogenesis will provide insights to behavioral responses in diseased states, advance the engineering of physiologically-relevant tissue models and provide biochemical clues for the design of therapeutic strategies. We review the applicability and limitations of the 2PEF microscope on the biophysical and molecular-level signatures of angiogenesis in various tissue models. Imaging techniques and strategies for best practices in 2PEF microscopy will be reviewed.
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Affiliation(s)
- Marcus Lee
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Sathya Kannan
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Giridharan Muniraj
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Vinicius Rosa
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Wen Feng Lu
- Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
| | - Jerry Y H Fuh
- Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
| | - Gopu Sriram
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Tong Cao
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
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Freymüller C, Kalinina S, Rück A, Sroka R, Rühm A. Quenched coumarin derivatives as fluorescence lifetime phantoms for NADH and FAD. JOURNAL OF BIOPHOTONICS 2021; 14:e202100024. [PMID: 33749988 DOI: 10.1002/jbio.202100024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/22/2021] [Accepted: 03/12/2021] [Indexed: 06/12/2023]
Abstract
Two-photon fluorescence lifetime imaging is a versatile laboratory technique in the field of biophotonics and its importance is also growing in the field of in vivo diagnostics for medical purposes. After years of experience in dermatology, endoscopic implementations of the technique are now posing new technical challenges. To develop, test, and compare instrumental solutions for this purpose suitable reference samples have been devised and tested. These reference samples can serve as reliable NADH- and FAD-mimicking optical phantoms for 2-photon fluorescence lifetime imaging, as they can be prepared relatively easily with reproducible and stable characteristics for this quite relevant diagnostic technique. The reference samples (mixtures of coumarin 1 and coumarin 6 in ethanol with suitable amounts of 4-hydroxy-TEMPO) have been tuned to exhibit spectral and temporal fluorescence characteristics very similar to those of NADH and FAD, the two molecules most frequently utilized to characterize cell metabolism.
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Affiliation(s)
- Christian Freymüller
- Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Planegg, Germany
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Sviatlana Kalinina
- Core Facility Confocal and Multiphoton Microscopy N24, University of Ulm, Ulm, Germany
| | - Angelika Rück
- Core Facility Confocal and Multiphoton Microscopy N24, University of Ulm, Ulm, Germany
| | - Ronald Sroka
- Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Planegg, Germany
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Adrian Rühm
- Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Planegg, Germany
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
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Santra K, Smith EA, Petrich JW, Song X. Photon Counting Data Analysis: Application of the Maximum Likelihood and Related Methods for the Determination of Lifetimes in Mixtures of Rose Bengal and Rhodamine B. J Phys Chem A 2016; 121:122-132. [PMID: 27936713 DOI: 10.1021/acs.jpca.6b10728] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is often convenient to know the minimum amount of data needed to obtain a result of desired accuracy and precision. It is a necessity in the case of subdiffraction-limited microscopies, such as stimulated emission depletion (STED) microscopy, owing to the limited sample volumes and the extreme sensitivity of the samples to photobleaching and photodamage. We present a detailed comparison of probability-based techniques (the maximum likelihood method and methods based on the binomial and the Poisson distributions) with residual minimization-based techniques for retrieving the fluorescence decay parameters for various two-fluorophore mixtures, as a function of the total number of photon counts, in time-correlated, single-photon counting experiments. The probability-based techniques proved to be the most robust (insensitive to initial values) in retrieving the target parameters and, in fact, performed equivalently to 2-3 significant figures. This is to be expected, as we demonstrate that the three methods are fundamentally related. Furthermore, methods based on the Poisson and binomial distributions have the desirable feature of providing a bin-by-bin analysis of a single fluorescence decay trace, which thus permits statistics to be acquired using only the one trace not only for the mean and median values of the fluorescence decay parameters but also for the associated standard deviations. These probability-based methods lend themselves well to the analysis of the sparse data sets that are encountered in subdiffraction-limited microscopies.
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Affiliation(s)
- Kalyan Santra
- Department of Chemistry, Iowa State University, and U.S. Department of Energy, Ames Laboratory , Ames, Iowa 50011, United States
| | - Emily A Smith
- Department of Chemistry, Iowa State University, and U.S. Department of Energy, Ames Laboratory , Ames, Iowa 50011, United States
| | - Jacob W Petrich
- Department of Chemistry, Iowa State University, and U.S. Department of Energy, Ames Laboratory , Ames, Iowa 50011, United States
| | - Xueyu Song
- Department of Chemistry, Iowa State University, and U.S. Department of Energy, Ames Laboratory , Ames, Iowa 50011, United States
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Santra K, Zhan J, Song X, Smith EA, Vaswani N, Petrich JW. What Is the Best Method to Fit Time-Resolved Data? A Comparison of the Residual Minimization and the Maximum Likelihood Techniques As Applied to Experimental Time-Correlated, Single-Photon Counting Data. J Phys Chem B 2016; 120:2484-90. [PMID: 26865463 DOI: 10.1021/acs.jpcb.6b00154] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The need for measuring fluorescence lifetimes of species in subdiffraction-limited volumes in, for example, stimulated emission depletion (STED) microscopy, entails the dual challenge of probing a small number of fluorophores and fitting the concomitant sparse data set to the appropriate excited-state decay function. This need has stimulated a further investigation into the relative merits of two fitting techniques commonly referred to as "residual minimization" (RM) and "maximum likelihood" (ML). Fluorescence decays of the well-characterized standard, rose bengal in methanol at room temperature (530 ± 10 ps), were acquired in a set of five experiments in which the total number of "photon counts" was approximately 20, 200, 1000, 3000, and 6000 and there were about 2-200 counts at the maxima of the respective decays. Each set of experiments was repeated 50 times to generate the appropriate statistics. Each of the 250 data sets was analyzed by ML and two different RM methods (differing in the weighting of residuals) using in-house routines and compared with a frequently used commercial RM routine. Convolution with a real instrument response function was always included in the fitting. While RM using Pearson's weighting of residuals can recover the correct mean result with a total number of counts of 1000 or more, ML distinguishes itself by yielding, in all cases, the same mean lifetime within 2% of the accepted value. For 200 total counts and greater, ML always provides a standard deviation of <10% of the mean lifetime, and even at 20 total counts there is only 20% error in the mean lifetime. The robustness of ML advocates its use for sparse data sets such as those acquired in some subdiffraction-limited microscopies, such as STED, and, more importantly, provides greater motivation for exploiting the time-resolved capacities of this technique to acquire and analyze fluorescence lifetime data.
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Affiliation(s)
- Kalyan Santra
- Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.,U.S. Department of Energy , Ames Laboratory, Ames, Iowa 50011, United States
| | - Jinchun Zhan
- Department of Electrical and Computer Engineering, Iowa State University , Ames, Iowa 50011, United States
| | - Xueyu Song
- Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.,U.S. Department of Energy , Ames Laboratory, Ames, Iowa 50011, United States
| | - Emily A Smith
- Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.,U.S. Department of Energy , Ames Laboratory, Ames, Iowa 50011, United States
| | - Namrata Vaswani
- Department of Electrical and Computer Engineering, Iowa State University , Ames, Iowa 50011, United States
| | - Jacob W Petrich
- Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.,U.S. Department of Energy , Ames Laboratory, Ames, Iowa 50011, United States
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Klemm M, Schweitzer D, Peters S, Sauer L, Hammer M, Haueisen J. FLIMX: A Software Package to Determine and Analyze the Fluorescence Lifetime in Time-Resolved Fluorescence Data from the Human Eye. PLoS One 2015; 10:e0131640. [PMID: 26192624 PMCID: PMC4507995 DOI: 10.1371/journal.pone.0131640] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 06/04/2015] [Indexed: 02/02/2023] Open
Abstract
Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a new technique for measuring the in vivo autofluorescence intensity decays generated by endogenous fluorophores in the ocular fundus. Here, we present a software package called FLIM eXplorer (FLIMX) for analyzing FLIO data. Specifically, we introduce a new adaptive binning approach as an optimal tradeoff between the spatial resolution and the number of photons required per pixel. We also expand existing decay models (multi-exponential, stretched exponential, spectral global analysis, incomplete decay) to account for the layered structure of the eye and present a method to correct for the influence of the crystalline lens fluorescence on the retina fluorescence. Subsequently, the Holm-Bonferroni method is applied to FLIO measurements to allow for group comparisons between patients and controls on the basis of fluorescence lifetime parameters. The performance of the new approaches was evaluated in five experiments. Specifically, we evaluated static and adaptive binning in a diabetes mellitus patient, we compared the different decay models in a healthy volunteer and performed a group comparison between diabetes patients and controls. An overview of the visualization capabilities and a comparison of static and adaptive binning is shown for a patient with macular hole. FLIMX’s applicability to fluorescence lifetime imaging microscopy is shown in the ganglion cell layer of a porcine retina sample, obtained by a laser scanning microscope using two-photon excitation.
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Affiliation(s)
- Matthias Klemm
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694, Ilmenau, Germany
- * E-mail:
| | - Dietrich Schweitzer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740, Jena, Germany
| | - Sven Peters
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740, Jena, Germany
| | - Lydia Sauer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740, Jena, Germany
| | - Martin Hammer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740, Jena, Germany
| | - Jens Haueisen
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694, Ilmenau, Germany
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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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Sagolla K, Löhmannsröben HG, Hille C. Time-resolved fluorescence microscopy for quantitative Ca2+ imaging in living cells. Anal Bioanal Chem 2013; 405:8525-37. [DOI: 10.1007/s00216-013-7290-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 07/31/2013] [Accepted: 08/01/2013] [Indexed: 11/28/2022]
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Resch-Genger U, Bremser W, Pfeifer D, Spieles M, Hoffmann A, DeRose PC, Zwinkels JC, Gauthier F, Ebert B, Taubert RD, Monte C, Voigt J, Hollandt J, Macdonald R. State-of-the art comparability of corrected emission spectra. 1. Spectral correction with physical transfer standards and spectral fluorescence standards by expert laboratories. Anal Chem 2012; 84:3889-98. [PMID: 22376085 DOI: 10.1021/ac2034503] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The development of fluorescence applications in the life and material sciences has proceeded largely without sufficient concern for the measurement uncertainties related to the characterization of fluorescence instruments. In this first part of a two-part series on the state-of-the-art comparability of corrected emission spectra, four National Metrology Institutes active in high-precision steady-state fluorometry performed a first comparison of fluorescence measurement capabilities by evaluating physical transfer standard (PTS)-based and reference material (RM)-based calibration methods. To identify achievable comparability and sources of error in instrument calibration, the emission spectra of three test dyes in the wavelength region from 300 to 770 nm were corrected and compared using both calibration methods. The results, obtained for typical spectrofluorometric (0°/90° transmitting) and colorimetric (45°/0° front-face) measurement geometries, demonstrated a comparability of corrected emission spectra within a relative standard uncertainty of 4.2% for PTS- and 2.4% for RM-based spectral correction when measurements and calibrations were performed under identical conditions. Moreover, the emission spectra of RMs F001 to F005, certified by BAM, Federal Institute for Materials Research and Testing, were confirmed. These RMs were subsequently used for the assessment of the comparability of RM-based corrected emission spectra of field laboratories using common commercial spectrofluorometers and routine measurement conditions in part 2 of this series (subsequent paper in this issue).
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Affiliation(s)
- Ute Resch-Genger
- Division I.5, BAM, Federal Institute for Materials Research and Testing, Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany.
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Resch-Genger U, Bremser W, Pfeifer D, Spieles M, Hoffmann A, DeRose PC, Zwinkels JC, Gauthier F, Ebert B, Taubert RD, Voigt J, Hollandt J, Macdonald R. State-of-the art comparability of corrected emission spectra. 2. Field laboratory assessment of calibration performance using spectral fluorescence standards. Anal Chem 2012; 84:3899-907. [PMID: 22376144 DOI: 10.1021/ac203451g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the second part of this two-part series on the state-of-the-art comparability of corrected emission spectra, we have extended this assessment to the broader community of fluorescence spectroscopists by involving 12 field laboratories that were randomly selected on the basis of their fluorescence measuring equipment. These laboratories performed a reference material (RM)-based fluorometer calibration with commercially available spectral fluorescence standards following a standard operating procedure that involved routine measurement conditions and the data evaluation software LINKCORR developed and provided by the Federal Institute for Materials Research and Testing (BAM). This instrument-specific emission correction curve was subsequently used for the determination of the corrected emission spectra of three test dyes, X, QS, and Y, revealing an average accuracy of 6.8% for the corrected emission spectra. This compares well with the relative standard uncertainties of 4.2% for physical standard-based spectral corrections demonstrated in the first part of this study (previous paper in this issue) involving an international group of four expert laboratories. The excellent comparability of the measurements of the field laboratories also demonstrates the effectiveness of RM-based correction procedures.
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Affiliation(s)
- Ute Resch-Genger
- Division I.5, BAM, Federal Institute for Materials Research and Testing, Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany.
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Talbot CB, Patalay R, Munro I, Warren S, Ratto F, Matteini P, Pini R, Breunig HG, König K, Chu AC, Stamp GW, Neil MAA, French PMW, Dunsby C. Application of ultrafast gold luminescence to measuring the instrument response function for multispectral multiphoton fluorescence lifetime imaging. OPTICS EXPRESS 2011; 19:13848-61. [PMID: 21934746 DOI: 10.1364/oe.19.013848] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
When performing multiphoton fluorescence lifetime imaging in multiple spectral emission channels, an instrument response function must be acquired in each channel if accurate measurements of complex fluorescence decays are to be performed. Although this can be achieved using the reference reconvolution technique, it is difficult to identify suitable fluorophores with a mono-exponential fluorescence decay across a broad emission spectrum. We present a solution to this problem by measuring the IRF using the ultrafast luminescence from gold nanorods. We show that ultrafast gold nanorod luminescence allows the IRF to be directly obtained in multiple spectral channels simultaneously across a wide spectral range. We validate this approach by presenting an analysis of multispectral autofluorescence FLIM data obtained from human skin ex vivo.
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