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Wang G, Li L, Sorrells JE, Chen J, Tu H. Gentle label-free nonlinear optical imaging relaxes linear-absorption-mediated triplet. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.09.561579. [PMID: 37873348 PMCID: PMC10592717 DOI: 10.1101/2023.10.09.561579] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Sample health is critical for live-cell fluorescence microscopy and has promoted light-sheet microscopy that restricts its ultraviolet-visible excitation to one plane inside a three-dimensional sample. It is thus intriguing that laser-scanning nonlinear optical microscopy, which similarly restricts its near-infrared excitation, has not broadly enabled gentle label-free molecular imaging. We hypothesize that intense near-infrared excitation induces phototoxicity via linear absorption of intrinsic biomolecules with subsequent triplet buildup, rather than the commonly assumed mechanism of nonlinear absorption. Using a reproducible phototoxicity assay based on the time-lapse elevation of auto-fluorescence (hyper-fluorescence) from a homogeneous tissue model (chicken breast), we provide strong evidence supporting this hypothesis. Our study justifies a simple imaging technique, e.g., rapidly scanned sub-80-fs excitation with full triplet-relaxation, to mitigate this ubiquitous linear-absorption-mediated phototoxicity independent of sample types. The corresponding label-free imaging can track freely moving C. elegans in real-time at an irradiance up to one-half of water optical breakdown.
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Li M, Razumtcev A, Turner GA, Hwang Y, Simpson GJ. Fast Diffusion Characterization by Multiphoton Excited Fluorescence Recovery while Photobleaching. Anal Chem 2023; 95:14331-14340. [PMID: 37699550 DOI: 10.1021/acs.analchem.3c02638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
Multiphoton-excited fluorescence recovery while photobleaching (FRWP) is demonstrated as a method for quantitative measurements of rapid molecular diffusion over microsecond to millisecond timescales. Diffusion measurements are crucial in assessing molecular mobility in cell biology, materials science, and pharmacology. Optical and fluorescence microscopy techniques enable non-invasive rapid analysis of molecular diffusion but can be challenging for systems with diffusion coefficients exceeding ∼100 μm2/s. As an example, fluorescence recovery after photobleaching (FRAP) operates on the implicit assumption of a comparatively fast photobleaching step prior to a relatively slow recovery and is not generally applicable for systems exhibiting substantial recovery during photobleaching. These challenges are exacerbated in multiphoton excitation by the lower excitation efficiency and competing effects from local heating. Herein, beam-scanning FRWP with patterned line-bleach illumination is introduced as a technique that addresses FRAP limitations and further extends its application range by measuring faster diffusion events. In FRWP, the recovery of fluorescence is continuously probed after each pass of a fast-scanning mirror, and the upper bound of measurable diffusion rates is, therefore, only limited by the mirror scanning frequency. A theoretical model describing transient fluctuations in fluorescence intensity arising as a result of combined contributions from photobleaching and localized photothermal effect is introduced along with a mathematical framework for quantifying fluorescence intensity temporal curves and recovering room-temperature diffusion coefficients. FRWP is then tested by characterization of normal diffusion of rhodamine-labeled bovine serum albumin, green fluorescence protein, and immunoglobulin G molecules in aqueous solutions of varying viscosity.
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Affiliation(s)
- Minghe Li
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Aleksandr Razumtcev
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Gwendylan A Turner
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Yechan Hwang
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Garth J Simpson
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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3
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Song J, Kang J, Kang U, Nam HS, Kim HJ, Kim RH, Kim JW, Yoo H. SNR enhanced high-speed two-photon microscopy using a pulse picker and time gating detection. Sci Rep 2023; 13:14244. [PMID: 37648768 PMCID: PMC10468500 DOI: 10.1038/s41598-023-41270-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 08/24/2023] [Indexed: 09/01/2023] Open
Abstract
Two-photon microscopy (TPM) is an attractive biomedical imaging method due to its large penetration depth and optical sectioning capability. In particular, label-free autofluorescence imaging offers various advantages for imaging biological samples. However, relatively low intensity of autofluorescence leads to low signal-to-noise ratio (SNR), causing practical challenges for imaging biological samples. In this study, we present TPM using a pulse picker to utilize low pulse repetition rate of femtosecond pulsed laser to increase the pulse peak power of the excitation source leading to higher emission of two-photon fluorescence with the same average illumination power. Stronger autofluorescence emission allowed us to obtain higher SNR images of arterial and liver tissues. In addition, by applying the time gating detection method to the pulse signals obtained by TPM, we were able to significantly reduce the background noise of two-photon images. As a result, our TPM system using the pulsed light source with a 19 times lower repetition rate allowed us to obtain the same SNR image more than 19 times faster with the same average power. Although high pulse energy can increase the photobleaching, we also observed that high-speed imaging with low total illumination energy can mitigate the photobleaching effect to a level similar to that of conventional illumination with a high repetition rate. We anticipate that this simple approach will provide guidance for SNR enhancement with high-speed imaging in TPM as well as other nonlinear microscopy.
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Affiliation(s)
- Jeonggeun Song
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Daejeon, 34141, South Korea
| | - Juehyung Kang
- Department of Biomedical Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul, 04763, Republic of Korea
| | - Ungyo Kang
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Daejeon, 34141, South Korea
| | - Hyeong Soo Nam
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Daejeon, 34141, South Korea
| | - Hyun Jung Kim
- Cardiovascular Center, Korea University Guro Hospital, 148 Gurodong-Ro, Seoul, 08308, South Korea
| | - Ryeong Hyeon Kim
- Cardiovascular Center, Korea University Guro Hospital, 148 Gurodong-Ro, Seoul, 08308, South Korea
| | - Jin Won Kim
- Cardiovascular Center, Korea University Guro Hospital, 148 Gurodong-Ro, Seoul, 08308, South Korea
| | - Hongki Yoo
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Daejeon, 34141, South Korea.
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Abstract
Endogenous photosensitizers play a critical role in both beneficial and harmful light-induced transformations in biological systems. Understanding their mode of action is essential for advancing fields such as photomedicine, photoredox catalysis, environmental science, and the development of sun care products. This review offers a comprehensive analysis of endogenous photosensitizers in human skin, investigating the connections between their electronic excitation and the subsequent activation or damage of organic biomolecules. We gather the physicochemical and photochemical properties of key endogenous photosensitizers and examine the relationships between their chemical reactivity, location within the skin, and the primary biochemical events following solar radiation exposure, along with their influence on skin physiology and pathology. An important take-home message of this review is that photosensitization allows visible light and UV-A radiation to have large effects on skin. The analysis presented here unveils potential causes for the continuous increase in global skin cancer cases and emphasizes the limitations of current sun protection approaches.
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Affiliation(s)
- Erick L Bastos
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
| | - Frank H Quina
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
- Department of Chemical Engineering, Polytechnic School, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
| | - Maurício S Baptista
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
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Abstract
Over the last half century, the autofluorescence of the metabolic cofactors NADH (reduced nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) has been quantified in a variety of cell types and disease states. With the spread of nonlinear optical microscopy techniques in biomedical research, NADH and FAD imaging has offered an attractive solution to noninvasively monitor cell and tissue status and elucidate dynamic changes in cell or tissue metabolism. Various tools and methods to measure the temporal, spectral, and spatial properties of NADH and FAD autofluorescence have been developed. Specifically, an optical redox ratio of cofactor fluorescence intensities and NADH fluorescence lifetime parameters have been used in numerous applications, but significant work remains to mature this technology for understanding dynamic changes in metabolism. This article describes the current understanding of our optical sensitivity to different metabolic pathways and highlights current challenges in the field. Recent progress in addressing these challenges and acquiring more quantitative information in faster and more metabolically relevant formats is also discussed.
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Affiliation(s)
- Irene Georgakoudi
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts, USA;
- Genetics, Molecular and Cellular Biology Program, Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA
| | - Kyle P Quinn
- Department of Biomedical Engineering and the Arkansas Integrative Metabolic Research Center, University of Arkansas, Fayetteville, Arkansas, USA
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Real-time optical redox imaging of cartilage metabolic response to mechanical loading. Osteoarthritis Cartilage 2019; 27:1841-1850. [PMID: 31513919 DOI: 10.1016/j.joca.2019.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 08/27/2019] [Accepted: 08/29/2019] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Metabolic dysregulation has recently been identified as a key feature of osteoarthritis. Mechanical overloading has been postulated as a primary cause of this metabolic response. Current methods of real-time metabolic activity analysis in cartilage are limited and challenging. However, optical redox imaging leverages the autofluorescence of co-enzymes NAD(P)H and FAD to provide dye-free real-time analysis of metabolic activity. This technique has not yet been applied to cartilage. This study aimed to assess the effects of a compressive load on cartilage using optical redox imaging. METHOD Cartilage samples were excised from porcine femoral condyles. To validate this imaging modality in cartilage, glycolysis was inhibited via 2-deoxy-D-glucose (2DG) and oxidative phosphorylation was inhibited by rotenone. Optical redox images were collected pre- and post-inhibition. To assess the effects of mechanical loading, samples were subjected to a compressive load and imaged for approximately 30 min. Load and strain parameters were determined using high-speed camera images in Matlab. A range of loading magnitudes and rates were applied across samples. RESULTS 2DG and rotenone demonstrated the expected inhibitory effects on fluorescence intensity in the channels corresponding to NAD(P)H and FAD, respectively. Mechanical loading induced an increase in NAD(P)H channel fluorescence which subsided by 30 min post-loading. Magnitude of loading parameters had mixed effects on metabolites. CONCLUSIONS Optical redox imaging provides an opportunity to assess real-time metabolic activity in cartilage. This approach revealed a metabolic response to a single load and can be used to provide insight into the role of metabolism in mechanically-mediated cartilage degradation.
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Blacker TS, Sewell MDE, Szabadkai G, Duchen MR. Metabolic Profiling of Live Cancer Tissues Using NAD(P)H Fluorescence Lifetime Imaging. Methods Mol Biol 2019; 1928:365-387. [PMID: 30725465 DOI: 10.1007/978-1-4939-9027-6_19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Altered metabolism is a hallmark of cancer, both resulting from and driving oncogenesis. The NAD and NADP redox couples play a key role in a large number of the metabolic pathways involved. In their reduced forms, NADH and NADPH, these molecules are intrinsically fluorescent. As the average time for fluorescence to be emitted following excitation by a laser pulse, the fluorescence lifetime, is exquisitely sensitive to changes in the local environment of the fluorophore, imaging the fluorescence lifetime of NADH and NADPH offers the potential for label-free monitoring of metabolic changes inside living tumors. Here, we describe the biological, photophysical, and methodological considerations required to establish fluorescence lifetime imaging (FLIM) of NAD(P)H as a routine method for profiling the metabolism of living cancer cells and tissues.
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Affiliation(s)
- Thomas S Blacker
- Research Department of Cell & Developmental Biology, University College London, London, UK.
- UCL Consortium for Mitochondrial Research, University College London, London, UK.
- Department of Physics & Astronomy, University College London, London, UK.
| | - Michael D E Sewell
- Research Department of Cell & Developmental Biology, University College London, London, UK
| | - Gyorgy Szabadkai
- Research Department of Cell & Developmental Biology, University College London, London, UK
- UCL Consortium for Mitochondrial Research, University College London, London, UK
- The Francis Crick Institute, London, UK
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Michael R Duchen
- Research Department of Cell & Developmental Biology, University College London, London, UK
- UCL Consortium for Mitochondrial Research, University College London, London, UK
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Marcek Chorvatova A, Kirchnerova J, Cagalinec M, Mateasik A, Chorvat D. Spectrally and spatially resolved laser-induced photobleaching of endogenous flavin fluorescence in cardiac myocytes. Cytometry A 2018; 95:13-23. [PMID: 30240113 PMCID: PMC6590054 DOI: 10.1002/cyto.a.23591] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 07/19/2018] [Accepted: 07/30/2018] [Indexed: 11/28/2022]
Abstract
Naturally occurring endogenous fluorescence of flavins, arising in response to excitation by visible light, offers broad opportunity to investigate mitochondrial metabolic state directly in living cells and tissues, including in clinical settings. However, photobleaching, the loss of the autofluorescence intensity following prolonged exposure to light is an inherent phenomenon occurring during the fluorescence acquisition, which can have a negative impact on the recorded data, particularly in the context of measurement of metabolic modulations in pathophysiological conditions. In the presented study, we present a detailed analysis of endogenous flavins fluorescence photobleaching arising in living cardiac cells during spectrally‐resolved confocal imaging. We demonstrate significant nonuniform photobleaching related to different bleaching rates of individual flavin components, resolved by linear spectral unmixing of the recorded signals. Induced photodamage was without effect on the cell morphology, but lead to significant modifications of the cell responsiveness to metabolic modulators and its contractility, suggesting functional metabolic alterations in the recorded cells. These findings point to the necessity of inducing limited photobleaching during metabolic screening in all studies involving visible light excitation and fluorescence acquisition in living cells. © 2018 The Authors Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry
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Affiliation(s)
- Alzbeta Marcek Chorvatova
- Department of Biophotonics, International Laser Centre, Ilkovicova 3, 84104, Bratislava, Slovakia.,Department of Biophysics, Faculty of Natural Sciences, University of Ss. Cyril and Methodius, J Herdu 1, 91702, Trnava, Slovakia
| | - Jana Kirchnerova
- Department of Biophotonics, International Laser Centre, Ilkovicova 3, 84104, Bratislava, Slovakia
| | - Michal Cagalinec
- Department of Biophotonics, International Laser Centre, Ilkovicova 3, 84104, Bratislava, Slovakia.,Department of Cellular Cardiology, Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 84505, Bratislava, Slovakia
| | - Anton Mateasik
- Department of Biophotonics, International Laser Centre, Ilkovicova 3, 84104, Bratislava, Slovakia
| | - Dusan Chorvat
- Department of Biophotonics, International Laser Centre, Ilkovicova 3, 84104, Bratislava, Slovakia
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9
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Palmer S, Litvinova K, Dunaev A, Yubo J, McGloin D, Nabi G. Optical redox ratio and endogenous porphyrins in the detection of urinary bladder cancer: A patient biopsy analysis. JOURNAL OF BIOPHOTONICS 2017; 10:1062-1073. [PMID: 27714989 DOI: 10.1002/jbio.201600162] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 08/10/2016] [Accepted: 08/21/2016] [Indexed: 06/06/2023]
Abstract
Bladder cancer is among the most common cancers in the UK and conventional detection techniques suffer from low sensitivity, low specificity, or both. Recent attempts to address the disparity have led to progress in the field of autofluorescence as a means to diagnose the disease with high efficiency, however there is still a lot not known about autofluorescence profiles in the disease. The multi-functional diagnostic system "LAKK-M" was used to assess autofluorescence profiles of healthy and cancerous bladder tissue to identify novel biomarkers of the disease. Statistically significant differences were observed in the optical redox ratio (a measure of tissue metabolic activity), the amplitude of endogenous porphyrins and the NADH/porphyrin ratio between tissue types. These findings could advance understanding of bladder cancer and aid in the development of new techniques for detection and surveillance.
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Affiliation(s)
- Scott Palmer
- Division of Imaging and Technology, University of Dundee, Ninewells Hospital and Medical School, James Arrott Drive, Dundee, UK DD1 9SY
| | - Karina Litvinova
- Optoelectronics and Biomedical Photonics Group, Aston Institute of Photonic Technologies, Aston University, Aston Triangle, Birmingham, UK B4 7ET
| | - Andrey Dunaev
- Biomedical Photonics Instrumentation Group, Scientific-Educational Centre of "Biomedical Engineering", Orel State University, Orel, Russia, 302020
| | - Ji Yubo
- Division of Imaging and Technology, University of Dundee, Ninewells Hospital and Medical School, James Arrott Drive, Dundee, UK DD1 9SY
| | - David McGloin
- SUPA, School of Science and Engineering, Ewing Building, University of Dundee, Nethergate, Dundee, UK DD1 4HN
| | - Ghulam Nabi
- Division of Imaging and Technology, University of Dundee, Ninewells Hospital and Medical School, James Arrott Drive, Dundee, UK DD1 9SY
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10
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Blacker TS, Berecz T, Duchen MR, Szabadkai G. Assessment of Cellular Redox State Using NAD(P)H Fluorescence Intensity and Lifetime. Bio Protoc 2017; 7:e2105. [PMID: 28286806 DOI: 10.21769/bioprotoc.2105] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
NADH and NADPH are redox cofactors, primarily involved in catabolic and anabolic metabolic processes respectively. In addition, NADPH plays an important role in cellular antioxidant defence. In live cells and tissues, the intensity of their spectrally-identical autofluorescence, termed NAD(P)H, can be used to probe the mitochondrial redox state, while their distinct enzyme-binding characteristics can be used to separate their relative contributions to the total NAD(P)H intensity using fluorescence lifetime imaging microscopy (FLIM). These protocols allow differences in metabolism to be detected between cell types and altered physiological and pathological states.
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Affiliation(s)
- Thomas S Blacker
- Consortium for Mitochondrial Research, Department of Cell & Developmental Biology, University College London, London, United Kingdom; Department of Physics & Astronomy, University College London, London, United Kingdom
| | - Tunde Berecz
- Consortium for Mitochondrial Research, Department of Cell & Developmental Biology, University College London, London, United Kingdom
| | - Michael R Duchen
- Consortium for Mitochondrial Research, Department of Cell & Developmental Biology, University College London, London, United Kingdom
| | - Gyorgy Szabadkai
- Consortium for Mitochondrial Research, Department of Cell & Developmental Biology, University College London, London, United Kingdom; Department of Biomedical Sciences, University of Padua and CNR Neuroscience Institute, Padua, Italy
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11
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Klinger A, Krapf L, Orzekowsky-Schroeder R, Koop N, Vogel A, Hüttmann G. Intravital autofluorescence 2-photon microscopy of murine intestinal mucosa with ultra-broadband femtosecond laser pulse excitation: image quality, photodamage, and inflammation. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:116001. [PMID: 26524678 DOI: 10.1117/1.jbo.20.11.116001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 09/16/2015] [Indexed: 06/05/2023]
Abstract
Ultra-broadband excitation with ultrashort pulses may enable simultaneous excitation of multiple endogenous fluorophores in vital tissue. Imaging living gut mucosa by autofluorescence 2-photon microscopy with more than 150 nm broad excitation at an 800-nm central wavelength from a sub-10 fs titanium-sapphire (Ti:sapphire) laser with a dielectric mirror based prechirp was compared to the excitation with 220 fs pulses of a tunable Ti:sapphire laser at 730 and 800 nm wavelengths. Excitation efficiency, image quality, and photochemical damage were evaluated. At similar excitation fluxes, the same image brightness was achieved with both lasers. As expected, with ultra-broadband pulses, fluorescence from NAD(P)H, flavines, and lipoproteins was observed simultaneously. However, nonlinear photodamage apparent as hyperfluorescence with functional and structural alterations of the tissue occurred earlier when the laser power was adjusted to the same image brightness. After only a few minutes, the immigration of polymorphonuclear leucocytes into the epithelium and degranulation of these cells, a sign of inflammation, was observed. Photodamage is promoted by the higher peak irradiances and/or by nonoptimal excitation of autofluorescence at the longer wavelength. We conclude that excitation with a tunable narrow bandwidth laser is preferable to ultra-broadband excitation for autofluorescence-based 2-photon microscopy, unless the spectral phase can be controlled to optimize excitation conditions.
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Affiliation(s)
- Antje Klinger
- University of Lübeck, Institute of Anatomy, Ratzeburger Allee 160, 23562, Lübeck, Germany
| | - Lisa Krapf
- University of Lübeck, Institute of Biomedical Optics, Peter-Monnik-Weg 4, 23562, Lübeck, Germany
| | | | - Norbert Koop
- University of Lübeck, Institute of Biomedical Optics, Peter-Monnik-Weg 4, 23562, Lübeck, Germany
| | - Alfred Vogel
- University of Lübeck, Institute of Biomedical Optics, Peter-Monnik-Weg 4, 23562, Lübeck, Germany
| | - Gereon Hüttmann
- University of Lübeck, Institute of Biomedical Optics, Peter-Monnik-Weg 4, 23562, Lübeck, GermanycAirway Research Center North (ARCN), Member of the German Center for Lung Research (DZL), Germany
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12
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Dalbosco L, Zanini G, D'Amato E, Tessarolo F, Boi S, Bauer P, Haase A, Antolini R. Photodamage in deep tissue two-photon optical biopsy of human skin. JOURNAL OF BIOPHOTONICS 2015; 8:816-825. [PMID: 25524048 DOI: 10.1002/jbio.201400083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 10/14/2014] [Accepted: 11/17/2014] [Indexed: 06/04/2023]
Abstract
Photodamage, induced by femtosecond laser radiation, was studied in thick samples of human skin tissue (healthy skin and neoplastic lesions). Photobleaching, photoionization, and thermomechanical damage effects were characterized comparatively. The laser power dependence of the damage rates allowed to connect macroscopic effects to underlying molecular processes. Optical effects were correlated to histopathological changes. Tissue alterations were found only from thermomechanical cavitation and limited to superficial layers of the epidermis. From the depth-dependencies of all damage thresholds a depth-dependent power-compensation scheme was defined allowing for damage-free deep tissue optical biopsy. Damage-induced luminescence pattern for different excitation powers and a corresponding threshold analysis.
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Affiliation(s)
- Luca Dalbosco
- BIOtech Center and Department of Industrial Engineering, University of Trento, via delle Regole 101, 38123, Mattarello, Italy
| | - Giulia Zanini
- Department of Physics, University of Trento, via Sommarive 14, 38123, Povo, Italy
| | - Elvira D'Amato
- Department of Physics, University of Trento, via Sommarive 14, 38123, Povo, Italy
| | - Francesco Tessarolo
- BIOtech Center and Department of Industrial Engineering, University of Trento, via delle Regole 101, 38123, Mattarello, Italy
- Healthcare Research and Innovation Program (IRCS), Bruno Kessler Foundation, via Sommarive 18, 38123, Trento, Italy
| | - Sebastiana Boi
- Department of Pathology, APSS, S. Chiara Hospital, Largo Medaglie d'Oro 9, 38122, Trento, Italy
| | - Paolo Bauer
- Department of Dermatology, APSS, S. Chiara Hospital, Largo Medaglie d'Oro 9, 38122, Trento, Italy
| | - Albrecht Haase
- Department of Physics, University of Trento, via Sommarive 14, 38123, Povo, Italy.
| | - Renzo Antolini
- Department of Physics, University of Trento, via Sommarive 14, 38123, Povo, Italy
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13
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Croce AC, Bottiroli G. Autofluorescence spectroscopy and imaging: a tool for biomedical research and diagnosis. Eur J Histochem 2014; 58:2461. [PMID: 25578980 PMCID: PMC4289852 DOI: 10.4081/ejh.2014.2461] [Citation(s) in RCA: 303] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 12/04/2014] [Indexed: 12/18/2022] Open
Abstract
Native fluorescence, or autofluorescence (AF), consists in the emission of light in the UV-visible, near-IR spectral range when biological substrates are excited with light at suitable wavelength. This is a well-known phenomenon, and the strict relationship of many endogenous fluorophores with morphofunctional properties of the living systems, influencing their AF emission features, offers an extremely powerful resource for directly monitoring the biological substrate condition. Starting from the last century, the technological progresses in microscopy and spectrofluorometry were convoying attention of the scientific community to this phenomenon. In the future, the interest in the autofluorescence will certainly continue. Current instrumentation and analytical procedures will likely be overcome by the unceasing progress in new devices for AF detection and data interpretation, while a progress is expected in the search and characterization of endogenous fluorophores and their roles as intrinsic biomarkers.
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Affiliation(s)
- A C Croce
- Institute of Molecular Genetics of the National Research Council, University of Pavia.
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14
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Galli R, Uckermann O, Andresen EF, Geiger KD, Koch E, Schackert G, Steiner G, Kirsch M. Intrinsic indicator of photodamage during label-free multiphoton microscopy of cells and tissues. PLoS One 2014; 9:e110295. [PMID: 25343251 PMCID: PMC4208781 DOI: 10.1371/journal.pone.0110295] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 09/11/2014] [Indexed: 12/04/2022] Open
Abstract
Multiphoton imaging has evolved as an indispensable tool in cell biology and holds prospects for clinical applications. When addressing endogenous signals such as coherent anti-Stokes Raman scattering (CARS) or second harmonic generation, it requires intense laser irradiation that may cause photodamage. We report that increasing endogenous fluorescence signal upon multiphoton imaging constitutes a marker of photodamage. The effect was studied on mouse brain in vivo and ex vivo, on ex vivo human brain tissue samples, as well as on glioblastoma cells in vitro, demonstrating that this phenomenon is common to a variety of different systems, both ex vivo and in vivo. CARS microscopy and vibrational spectroscopy were used to analyze the photodamage. The development of a standard easy-to-use model that employs rehydrated cryosections allowed the characterization of the irradiation-induced fluorescence and related it to nonlinear photodamage. In conclusion, the monitoring of endogenous two-photon excited fluorescence during label-free multiphoton microscopy enables to estimate damage thresholds ex vivo as well as detect photodamage during in vivo experiments.
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Affiliation(s)
- Roberta Galli
- Clinical Sensoring and Monitoring, Anesthesiology and Intensive Care Medicine, Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Ortrud Uckermann
- Neurosurgery, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
| | - Elisabeth F. Andresen
- Neurosurgery, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
- CRTD/DFG-Center for Regenerative Therapies Dresden - Cluster of Excellence, Dresden, Germany
| | - Kathrin D. Geiger
- Neuropathology, Institute for Pathology, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
| | - Edmund Koch
- Clinical Sensoring and Monitoring, Anesthesiology and Intensive Care Medicine, Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Gabriele Schackert
- Neurosurgery, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
| | - Gerald Steiner
- Clinical Sensoring and Monitoring, Anesthesiology and Intensive Care Medicine, Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Matthias Kirsch
- Neurosurgery, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
- CRTD/DFG-Center for Regenerative Therapies Dresden - Cluster of Excellence, Dresden, Germany
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15
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Weber P, Wagner M, Kioschis P, Kessler W, Schneckenburger H. Tumor cell differentiation by label-free fluorescence microscopy. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:101508. [PMID: 23223984 DOI: 10.1117/1.jbo.17.10.101508] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Autofluorescence spectra, images, and decay kinetics of U251-MG glioblastoma cells prior and subsequent to activation of tumor suppressor genes are compared. While phase contrast images and fluorescence intensity patterns of tumor (control) cells and less malignant cells are similar, differences can be deduced from autofluorescence spectra and decay kinetics. In particular, upon near UV excitation, the fluorescence ratio of the free and protein-bound coenzyme nicotinamid adenine dinucleotide depends on the state of malignancy and reflects different cytoplasmic (including lysosomal) and mitochondrial contributions. While larger numbers of fluorescence spectra are evaluated by principal component analysis, a multivariate data analysis method, additional information on cell metabolism is obtained from spectral imaging and fluorescence lifetime imaging microscopy.
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Affiliation(s)
- Petra Weber
- Institut für Angewandte Forschung, Hochschule Aalen, Beethovenstr. 1, 73430 Aalen, Germany
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16
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Vergen J, Hecht C, Zholudeva LV, Marquardt MM, Hallworth R, Nichols MG. Metabolic imaging using two-photon excited NADH intensity and fluorescence lifetime imaging. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2012; 18:761-70. [PMID: 22832200 PMCID: PMC3842212 DOI: 10.1017/s1431927612000529] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Metabolism and mitochondrial dysfunction are known to be involved in many different disease states. We have employed two-photon fluorescence imaging of intrinsic mitochondrial reduced nicotinamide adenine dinucleotide (NADH) to quantify the metabolic state of several cultured cell lines, multicell tumor spheroids, and the intact mouse organ of Corti. Historically, fluorescence intensity has commonly been used as an indicator of the NADH concentration in cells and tissues. More recently, fluorescence lifetime imaging has revealed that changes in metabolism produce not only changes in fluorescence intensity, but also significant changes in the lifetimes and concentrations of free and enzyme-bound pools of NADH. Since NADH binding changes with metabolic state, this approach presents a new opportunity to track the cellular metabolic state.
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Affiliation(s)
- Jorge Vergen
- Department of Physics, Creighton University, 2500 California Plaza, Omaha, NE 68178
| | - Clifford Hecht
- Department of Physics, Creighton University, 2500 California Plaza, Omaha, NE 68178
| | | | - Meg M. Marquardt
- Department of Physics, Creighton University, 2500 California Plaza, Omaha, NE 68178
| | - Richard Hallworth
- Department of Biomedical Sciences, Creighton University, 2500 California Plaza, Omaha, NE 68178
| | - Michael G. Nichols
- Department of Physics, Creighton University, 2500 California Plaza, Omaha, NE 68178
- Corresponding Author: Phone: 402.280.2159; FAX: 402.280.2140;
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17
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SCHNECKENBURGER H, WEBER P, WAGNER M, SCHICKINGER S, RICHTER V, BRUNS T, STRAUSS W, WITTIG R. Light exposure and cell viability in fluorescence microscopy. J Microsc 2011; 245:311-8. [DOI: 10.1111/j.1365-2818.2011.03576.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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18
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Orzekowsky-Schroeder R, Klinger A, Martensen B, Blessenohl M, Gebert A, Vogel A, Hüttmann G. In vivo spectral imaging of different cell types in the small intestine by two-photon excited autofluorescence. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:116025. [PMID: 22112130 DOI: 10.1117/1.3655587] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Spectrally resolved two-photon excited autofluorescence imaging is used to distinguish different cell types and functional areas during dynamic processes in the living gut. Excitation and emission spectra of mucosal tissue and tissue components are correlated to spectra of endogenous chromophores. We show that selective excitation with only two different wavelengths within the tuning range of a Ti:sapphire femtosecond laser system yields excellent discrimination between enterocytes, antigen presenting cells and lysosomes based on the excitation and emission properties of their autofluorescence. The method is employed for time-lapse microscopy over up to 8 h. Changes of the spectral signature with the onset of photodamage are demonstrated, and their origin is discussed.
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19
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Hasegawa M, Shiina T, Terazima M, Kumazaki S. Selective Excitation of Photosystems in Chloroplasts Inside Plant Leaves Observed by Near-Infrared Laser-Based Fluorescence Spectral Microscopy. ACTA ACUST UNITED AC 2009; 51:225-38. [DOI: 10.1093/pcp/pcp182] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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20
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Raimondi V, Agati G, Cecchi G, Gomoiu I, Lognoli D, Palombi L. In vivo real-time recording of UV-induced changes in the autofluorescence of a melanin-containing fungus using a micro-spectrofluorimeter and a low-cost webcam. OPTICS EXPRESS 2009; 17:22735-22746. [PMID: 20052199 DOI: 10.1364/oe.17.022735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
An optical epifluorescence microscope, coupled to a CCD camera, a standard webcam and a microspectrofluorimeter, are used to record in vivo real-time changes in the autofluorescence of spores and hyphae in Aspergillus niger, a fungus containing melanin, while exposed to UV irradiation. The results point out major changes in both signal intensity and the spectral shape of the autofluorescence signal after only few minutes of exposure, and can contribute to the interpretation of data obtained with other fluorescence techniques, including those, such as GPF labeling, in which endogenous fluorophores constitute a major disturbance.
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Affiliation(s)
- V Raimondi
- Nello Carrara Applied Physics Institute - National Research Council, Via Madonna del Piano 10, I- 50019 Sesto Fiorentino, Firenze, Italy.
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21
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Kumar S, Dunsby C, De Beule PAA, Owen DM, Anand U, Lanigan PMP, Benninger RKP, Davis DM, Neil MAA, Anand P, Benham C, Naylor A, French PMW. Multifocal multiphoton excitation and time correlated single photon counting detection for 3-D fluorescence lifetime imaging. OPTICS EXPRESS 2007; 15:12548-61. [PMID: 19550524 DOI: 10.1364/oe.15.012548] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We report a multifocal multiphoton time-correlated single photon counting (TCSPC) fluorescence lifetime imaging (FLIM) microscope system that uses a 16 channel multi-anode PMT detector. Multiphoton excitation minimizes out-of-focus photobleaching, multifocal excitation reduces non-linear in-plane photobleaching effects and TCSPC electronics provide photon-efficient detection of the fluorescence decay profile. TCSPC detection is less prone to bleaching- and movement-induced artefacts compared to wide-field time-gated or frequency-domain FLIM. This microscope is therefore capable of acquiring 3-D FLIM images at significantly increased speeds compared to single beam multiphoton microscopy and we demonstrate this with live cells expressing a GFP tagged protein. We also apply this system to time-lapse FLIM of NAD(P)H autofluorescence in single live cells and report measurements on the change in the fluorescence decay profile following the application of a known metabolic inhibitor.
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22
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Tiede LM, Rocha-Sanchez SM, Hallworth R, Nichols MG, Beisel K. Determination of hair cell metabolic state in isolated cochlear preparations by two-photon microscopy. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:021004. [PMID: 17477711 PMCID: PMC1992521 DOI: 10.1117/1.2714777] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Currently there is no accepted method to measure the metabolic status of the organ of Corti. Since metabolism and mitochondrial dysfunction are expected to play a role in many different hearing disorders, here for the first time we employ two-photon metabolic imaging to assess the metabolic status of the cochlea. When excited with ultrashort pulses of 740-nm light, both inner and outer hair cells in isolated murine cochlear preparations exhibited intrinsic fluorescence. This fluorescence is characterized and shown to be consistent with a mixture of oxidized flavoproteins (Fp) and reduced nicotinamide adenine dinucleotide (NADH). The location of the fluorescence within hair cells is also consistent with the different mitochondrial distributions in these cell types. Treatments with cyanide and mitochondrial uncouplers show that hair cells are metabolically active. Both NADH and Fp in inner hair cells gradually become completely oxidized within 50 min from the time of death of the animal. Outer hair cells show similar trends but are found to have greater variability. We show that it is possible to use two-photon metabolic imaging to assess metabolism in the mouse organ of Corti.
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Affiliation(s)
- Leann M Tiede
- Creighton University, Department of Biomedical Sciences, Omaha, Nebraska 68178, USA.
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