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Hernández-Mendoza GA, Aguirre-Olivas D, González-Gutiérrez M, Leal HJ, Qureshi N, Treviño-Palacios CG, Peón J, De-Miguel FF. Fluorescence of serotonin in the visible spectrum upon multiphotonic photoconversion. BIOMEDICAL OPTICS EXPRESS 2020; 11:1432-1448. [PMID: 32206420 PMCID: PMC7075609 DOI: 10.1364/boe.380412] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/05/2019] [Accepted: 01/02/2020] [Indexed: 06/01/2023]
Abstract
The vital molecule serotonin modulates the functioning of the nervous system. The chemical characteristics of serotonin provide multiple advantages for its study in living or fixed tissue. Serotonin has the capacity to emit fluorescence directly and indirectly through chemical intermediates in response to mono- and multiphoton excitation. However, the fluorescent emissions are multifactorial and their dependence on the concentration, excitation wavelength and laser intensity still need a comprehensive study. Here we studied the fluorescence of serotonin excited multiphotonically with near-infrared light. Experiments were conducted in a custom-made multiphoton microscope coupled to a monochromator and a photomultiplier that collected the emissions. We show that the responses of serotonin to multiphoton stimulation are highly non-linear. The well-known violet emission having a 340 nm peak was accompanied by two other emissions in the visible spectrum. The best excitor wavelength to produce both emissions was 700 nm. A green emission with a ∼ 500 nm peak was similar to a previously described fluorescence in response to longer excitation wavelengths. A new blue emission with a ∼ 405 nm peak was originated from the photoconversion of serotonin to a relatively stable product. Such a reaction could be reproduced by irradiation of serotonin with high laser power for 30 minutes. The absorbance of the new compound expanded from ∼ 315 to ∼ 360 nm. Excitation of the irradiated solution monophotonically with 350 nm or biphotonically with 700 nm similarly generated the 405 nm blue emission. Our data are presented quantitatively through the design of a single geometric chart that combines the intensity of each emission in response to the serotonin concentration, excitation wavelengths and laser intensity. The autofluorescence of serotonin in addition to the formation of the two compounds emitting in the visible spectrum provides diverse possibilities for the quantitative study of the dynamics of serotonin in living tissue.
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Affiliation(s)
- Guillermo A. Hernández-Mendoza
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México. Circuito Exterior, Ciudad Universitaria, 04510, D. F., Mexico
- Instituto de Ciencias Aplicadas y Tecnología, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de Mexico, 04510, Mexico
| | - Dilia Aguirre-Olivas
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México. Circuito Exterior, Ciudad Universitaria, 04510, D. F., Mexico
| | - Mario González-Gutiérrez
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de Mexico, 04510, Mexico
| | - Héctor J. Leal
- Facultad de Ingeniería, Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, Ciudad de Mexico, 04510, Mexico
| | - Naser Qureshi
- Instituto de Ciencias Aplicadas y Tecnología, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de Mexico, 04510, Mexico
| | - Carlos G. Treviño-Palacios
- Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro #1, 72840 Tonantzintla, Puebla, Mexico
| | - Jorge Peón
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de Mexico, 04510, Mexico
| | - Francisco F. De-Miguel
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México. Circuito Exterior, Ciudad Universitaria, 04510, D. F., Mexico
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2
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Swain BC, Das AK, Tripathy U. Probing third-order nonlinearity in serotonin: A Z-scan study. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2019; 223:117319. [PMID: 31280124 DOI: 10.1016/j.saa.2019.117319] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 06/24/2019] [Accepted: 06/25/2019] [Indexed: 06/09/2023]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is a crucial endogenous monoamine neurotransmitter that modulates neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. There have been numerous attempts to study the biochemical and photophysical properties of serotonin to carry out its molecular imaging and quantitative estimation. Here, we investigate the properties of serotonin at physiological concentration and pH using a continuous wave (CW) laser excitation closed-aperture (CA) Z-scan technique. Serotonin is packaged at high concentration inside the acidic environment of vesicles, and upon release gets diluted at the release sites in a neutral pH environment. Our solution-based measurements indicate that serotonin showed negative refractive nonlinearity and positive absorptive nonlinearity at a neutral pH. However, in the acidic medium, it showed negative refractive nonlinearity and mostly negative absorptive nonlinearity. The effect of excitation laser power on the observed nonlinearity is also verified. We attribute the origin of the nonlinearity in serotonin to the thermal lensing effect. Our robust and straightforward strategy to probe the monoamine neurotransmitter properties will provide new avenues to investigate serotonergic processes.
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Affiliation(s)
- Bikash Chandra Swain
- Department of Applied Physics, Indian Institute of Technology (Indian School of Mines) Dhanbad, Jharkhand 826004, India
| | - Anand Kant Das
- Institute of Applied Physics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Umakanta Tripathy
- Department of Applied Physics, Indian Institute of Technology (Indian School of Mines) Dhanbad, Jharkhand 826004, India.
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3
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Label-free imaging of neurotransmitters in live brain tissue by multi-photon ultraviolet microscopy. Neuronal Signal 2018; 2:NS20180132. [PMID: 32714595 PMCID: PMC7373235 DOI: 10.1042/ns20180132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 10/20/2018] [Accepted: 10/29/2018] [Indexed: 12/20/2022] Open
Abstract
Visualizing small biomolecules in living cells remains a difficult challenge. Neurotransmitters provide one of the most frustrating examples of this difficulty, as our understanding of signaling in the brain critically depends on our ability to follow the neurotransmitter traffic. Last two decades have seen considerable progress in probing some of the neurotransmitters, e.g. by using false neurotransmitter mimics, chemical labeling techniques, or direct fluorescence imaging. Direct imaging harnesses the weak UV fluorescence of monoamines, which are some of the most important neurotransmitters controlling mood, memory, appetite, and learning. Here we describe the progress in imaging of these molecules using the least toxic direct excitation route found so far, namely multi-photon (MP) imaging. MP imaging of serotonin, and more recently that of dopamine, has allowed researchers to determine the location of the vesicles, follow their intracellular dynamics, probe their content, and monitor their release. Recent developments have even allowed ratiometric quantitation of the vesicular content. This review shows that MP ultraviolet (MP-UV) microscopy is an effective but underutilized method for imaging monoamine neurotransmitters in neurones and brain tissue.
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Guo Y, Lu J, Kang Q, Fang M, Yu L. Fabrication of Biocompatible, Luminescent Supramolecular Structures and Their Applications in the Detection of Dopamine. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9195-9202. [PMID: 30001135 DOI: 10.1021/acs.langmuir.8b01548] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Supramolecular materials assembled by amide-functionalized surface active ionic liquid, N-dodecyl- N'-acetamido imidazolium bromide ([C12ImCONH2]Br), and europium-containing polyoxometalates (Eu-POM) were fabricated in aqueous solution by a one-step method via ionic self-assembly strategy. The [C12ImCONH2]Br/Eu-POM supramolecular structures exhibit favorable fluorescence properties and represent a 15-fold increase in quantum yield (∼13.68%) compared to Eu-POM. Besides, more fluorescence was quenched obviously with the increasing concentration of dopamine (DA) (within the range of 0-100 μM), based on which DA monitoring could be achieved. The detection limit was identified to be 0.1 μM. The supramolecular nanoparticles are highly specific for the detection of DA. In addition, the hybrid assemblies display not only low cytotoxicity but also excellent biocompatibility to MC3T3-E1 cells. As a result, as-prepared supramolecular materials with these superior properties show the promising application in some fields such as biochemistry and biomedical science.
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Affiliation(s)
- Yongxian Guo
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education , Shandong University , Jinan 250100 , P.R. China
| | - Jie Lu
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education , Shandong University , Jinan 250100 , P.R. China
| | - Qi Kang
- College of Chemistry, Chemical Engineering and Materials Science , Shandong Normal University , Jinan 250014 , P. R. China
| | - Ming Fang
- Department of Chemistry , University of Houston , Houston 77204 , United States
| | - Li Yu
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education , Shandong University , Jinan 250100 , P.R. China
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5
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Bera K, Das AK, Rakshit A, Sarkar B, Rawat A, Maity BK, Maiti S. Fluorogenic Detection of Monoamine Neurotransmitters in Live Cells. ACS Chem Neurosci 2018; 9:469-474. [PMID: 29226666 DOI: 10.1021/acschemneuro.7b00391] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Monoamine neurotransmission is key to neuromodulation, but imaging monoamines in live neurons has remained a challenge. Here we show that externally added ortho-phthalaldehyde (OPA) can permeate live cells and form bright fluorogenic adducts with intracellular monoamines (e.g., serotonin, dopamine, and norepinephrine) and with L-DOPA, which can be imaged sensitively using conventional single-photon excitation in a fluorescence microscope. The peak excitation and emission wavelengths (λex = 401 nm and λem = 490 nm for serotonin; λex = 446 nm and λem = 557 nm for dopamine; and λex = 446 nm and λem = 544 nm for norepinephrine, respectively) are accessible to most modern confocal imaging instruments. The identity of monoamine containing structures (possibly neurotransmitter vesicles) in serotonergic RN46A cells is established by quasi-simultaneous imaging of serotonin using three-photon excitation microscopy. Mass spectrometry of cell extracts and of in vitro solutions helps us identify the chemical nature of the adducts and establishes the reaction mechanisms. Our method has low toxicity, high selectivity, and the ability to directly report the location and concentration of monoamines in live cells.
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Affiliation(s)
- Kallol Bera
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Anand Kant Das
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Ananya Rakshit
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Bidyut Sarkar
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Anoop Rawat
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Barun Kumar Maity
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Sudipta Maiti
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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6
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Das AK, Maity BK, Surendran D, Tripathy U, Maiti S. Label-Free Ratiometric Imaging of Serotonin in Live Cells. ACS Chem Neurosci 2017; 8:2369-2373. [PMID: 28796481 DOI: 10.1021/acschemneuro.7b00132] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Ratiometric imaging can quantitatively measure changes in cellular analyte concentrations using specially designed fluorescent labels. We describe a label-free ratiometric imaging technique for direct detection of changes in intravesicular serotonin concentration in live cells. At higher concentrations, serotonin forms transient oligomers whose ultraviolet emission is shifted to longer wavelengths. We access the ultraviolet/blue emission using relatively benign three-photon excitation and split it into two imaging channels, whose ratio reports the concentration. The technique is sensitive at a physiologically relevant concentration range (10-150 mM serotonin). As a proof of principle, we measure the increase of intravesicular serotonin concentration with the addition of external serotonin. In general, since emission spectra of molecules are often sensitive to concentration, our method may be applicable to other natively fluorescent intracellular molecules which are present at high concentrations.
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Affiliation(s)
- Anand Kant Das
- Department
of Chemical Sciences, Tata Institute of Fundamental Research (TIFR), Homi Bhabha Road, Colaba,
Mumbai 400005, India
| | - Barun Kumar Maity
- Department
of Chemical Sciences, Tata Institute of Fundamental Research (TIFR), Homi Bhabha Road, Colaba,
Mumbai 400005, India
| | - Dayana Surendran
- Department
of Chemical Sciences, Tata Institute of Fundamental Research (TIFR), Homi Bhabha Road, Colaba,
Mumbai 400005, India
| | - Umakanta Tripathy
- Department
of Applied Physics, Indian Institute of Technology (Indian School of Mines), Dhanbad, 826004 Jharkhand, India
| | - Sudipta Maiti
- Department
of Chemical Sciences, Tata Institute of Fundamental Research (TIFR), Homi Bhabha Road, Colaba,
Mumbai 400005, India
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7
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Croce AC, Bottiroli G. Autofluorescence Spectroscopy for Monitoring Metabolism in Animal Cells and Tissues. Methods Mol Biol 2017; 1560:15-43. [PMID: 28155143 DOI: 10.1007/978-1-4939-6788-9_2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Excitation of biological substrates with light at a suitable wavelength can give rise to a light emission in the ultraviolet (UV)-visible, near-infrared (IR) spectral range, called autofluorescence (AF). This is a widespread phenomenon, ascribable to the general presence of biomolecules acting as endogenous fluorophores (EFs) in the organisms of the whole life kingdom. In cytochemistry and histochemistry, AF is often an unwanted signal enhancing the background and affecting in particular the detection of low signals or rare positive labeling spots of exogenous markers. Conversely, AF is increasingly considered as a powerful diagnostic tool because of its role as an intrinsic biomarker directly dependent on the nature, amount, and microenvironment of the EFs, in a strict relationship with metabolic processes and structural organization of cells and tissues. As a consequence, AF carries multiple information that can be decrypted by a proper analysis of the overall emission signal, allowing the characterization and monitoring of cell metabolism in situ, in real time and in the absence of perturbation from exogenous markers. In the animal kingdom, AF studies at the cellular level take advantage of the essential presence of NAD(P)H and flavins, primarily acting as coenzymes at multiple steps of common metabolic pathways for energy production, reductive biosynthesis and antioxidant defense. Additional EFs such as vitamin A, porphyrins, lipofuscins, proteins, and neuromediators can be detected in different kinds of cells and bulk tissues, and can be exploited as photophysical biomarkers of specific normal or altered morphofunctional properties, from the retinoid storage in the liver to aging processes, metabolic disorders or cell transformation processes. The AF phenomenon involves all living system, and literature reports numerous investigations and diagnostic applications of AF, taking advantage of continuously developing self-assembled or commercial instrumentation and measuring procedures, making almost impossible to provide their comprehensive description. Therefore a brief summary of the history of AF observations and of the development of measuring systems is provided, along with a description of the most common EFs and their metabolic significance. From our direct experience, examples of AF imaging and microspectrofluorometric procedures performed under a single excitation in the near-UV range for cell and tissue metabolism studies are then reported.
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Affiliation(s)
- Anna C Croce
- Institute of Molecular Genetics (IGM) - CNR, via Abbiategrasso, 207, 27100, Pavia, Italy.
| | - Giovanni Bottiroli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
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8
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Roshchina VV. The Fluorescence Methods to Study Neurotransmitters (Biomediators) in Plant Cells. J Fluoresc 2016; 26:1029-43. [DOI: 10.1007/s10895-016-1791-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 03/27/2016] [Indexed: 12/23/2022]
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9
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Trägårdh J, Robb G, Amor R, Amos WB, Dempster J, McConnell G. Exploration of the two-photon excitation spectrum of fluorescent dyes at wavelengths below the range of the Ti:Sapphire laser. J Microsc 2015; 259:210-8. [PMID: 25946127 PMCID: PMC4700633 DOI: 10.1111/jmi.12255] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 03/20/2015] [Indexed: 11/28/2022]
Abstract
We have studied the wavelength dependence of the two-photon excitation efficiency for a number of common UV excitable fluorescent dyes; the nuclear stains DAPI, Hoechst and SYTOX Green, chitin- and cellulose-staining dye Calcofluor White and Alexa Fluor 350, in the visible and near-infrared wavelength range (540-800 nm). For several of the dyes, we observe a substantial increase in the fluorescence emission intensity for shorter excitation wavelengths than the 680 nm which is the shortest wavelength usually available for two-photon microscopy. We also find that although the rate of photo-bleaching increases at shorter wavelengths, it is still possible to acquire many images with higher fluorescence intensity. This is particularly useful for applications where the aim is to image the structure, rather than monitoring changes in emission intensity over extended periods of time. We measure the excitation spectrum when the dyes are used to stain biological specimens to get a more accurate representation of the spectrum of the dye in a cell environment as compared to solution-based measurements.
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Affiliation(s)
- J Trägårdh
- Centre for Biophotonics, Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - G Robb
- Centre for Biophotonics, Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - R Amor
- Centre for Biophotonics, Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - W B Amos
- Centre for Biophotonics, Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
- MRC Laboratory of Molecular Biology, Cambridge, U.K
| | - J Dempster
- Centre for Biophotonics, Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
| | - G McConnell
- Centre for Biophotonics, Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K
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10
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Botchway SW, Scherer KM, Hook S, Stubbs CD, Weston E, Bisby RH, Parker AW. A series of flexible design adaptations to the Nikon E-C1 and E-C2 confocal microscope systems for UV, multiphoton and FLIM imaging. J Microsc 2015; 258:68-78. [PMID: 25664385 DOI: 10.1111/jmi.12218] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 12/17/2014] [Indexed: 12/16/2022]
Abstract
Multiphoton microscopy is widely employed in the life sciences using extrinsic fluorescence of low- and high-molecular weight labels with excitation and emission spectra in the visible and near infrared regions. For imaging of intrinsic and extrinsic fluorophores with excitation spectra in the ultraviolet region, multiphoton excitation with one- or two-colour lasers avoids the need for ultraviolet-transmitting excitation optics and has advantages in terms of optical penetration in the sample and reduced phototoxicity. Excitation and detection of ultraviolet emission around 300 nm and below in a typical inverted confocal microscope is more difficult and requires the use of expensive quartz optics including the objective. In this technical note we describe the adaptation of a commercial confocal microscope (Nikon, Japan E-C1 or E-C2) for versatile use with Ti-sapphire and OPO laser sources and the addition of a second detection channel that enables detection of ultraviolet fluorescence and increases detection sensitivity in a typical fluorescence lifetime imaging microscopy experiment. Results from some experiments with this setup illustrate the resulting capabilities.
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Affiliation(s)
- Stanley W Botchway
- Central Laser Facility, STFC, Rutherford Appleton Laboratory, Research Complex at Harwell, Harwell Oxford, Didcot, UK
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11
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Hackl C, Beyreiss R, Geissler D, Jezierski S, Belder D. Rapid prototyping of electrochromatography chips for improved two-photon excited fluorescence detection. Anal Chem 2014; 86:3773-9. [PMID: 24666258 DOI: 10.1021/ac500793e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present study, we introduce two-photon excitation at 532 nm for label-free fluorescence detection in chip electrochromatography. Two-photon excitation at 532 nm offers a promising alternative to one-photon excitation at 266 nm, as it enables the use of economic chip materials instead of fused silica. In order to demonstrate these benefits, one-photon and two-photon induced fluorescence detection are compared in different chip layouts and materials with respect to the achievable sensitivity in the detection of polycyclic aromatic hydrocarbons (PAHs). Customized chromatography chips with cover or bottom slides of different material and thickness are produced by means of a rapid prototyping method based on liquid-phase lithography. The design of thin bottom chips (180 μm) enables the use of high-performance immersion objectives with low working distances, which allows one to exploit the full potential of two-photon excitation for a sensitive detection. The developed method is applied for label-free analysis of PAHs separated on a polymer monolith inside polymer glass sandwich chips made from fused silica or soda-lime glass. The obtained limits of detection range from 40 nM to 1.95 μM, with similar sensitivities in fused silica thin bottom chips for one-photon and two-photon excitation. In deep-UV non- or less-transparent devices two-photon excitation is mandatory for label-free detection of aromatics with high sensitivity.
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Affiliation(s)
- Claudia Hackl
- Institut für Analytische Chemie, Universität Leipzig , Linnéstraße 3, 04103 Leipzig, Germany
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12
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Beyreiss R, Geißler D, Ohla S, Nagl S, Posch TN, Belder D. Label-free fluorescence detection of aromatic compounds in chip electrophoresis applying two-photon excitation and time-correlated single-photon counting. Anal Chem 2013; 85:8150-7. [PMID: 23944704 DOI: 10.1021/ac4010937] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, we introduce time-resolved fluorescence detection with two-photon excitation at 532 nm for label-free analyte determination in microchip electrophoresis. In the developed method, information about analyte fluorescence lifetimes is collected by time-correlated single-photon counting, improving reliable peak assignment in electrophoretic separations. The determined limits of detection for serotonin, propranolol, and tryptophan were 51, 37, and 280 nM, respectively, using microfluidic chips made of fused silica. Applying two-photon excitation microchip separations and label-free detection could also be performed in borosilicate glass chips demonstrating the potential for label-free fluorescence detection in non-UV-transparent devices. Microchip electrophoresis with two-photon excited fluorescence detection was then applied for analyses of active compounds in plant extracts. Harmala alkaloids present in methanolic plant extracts from Peganum harmala could be separated within seconds and detected with on-the-fly determination of fluorescence lifetimes.
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Affiliation(s)
- Reinhild Beyreiss
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany
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13
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Bisby RH, Botchway SW, Hadfield JA, McGown AT, Parker AW, Scherer KM. Fluorescence lifetime imaging of E-combretastatin uptake and distribution in live mammalian cells. Eur J Cancer 2011; 48:1896-903. [PMID: 22209092 DOI: 10.1016/j.ejca.2011.11.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 11/04/2011] [Accepted: 11/24/2011] [Indexed: 11/26/2022]
Abstract
To investigate within live mammalian cells the uptake and disposition of combretastatins, fluorescence lifetime imaging was used with two-photon excitation (2PE). Combretastatin A4 (CA4) and analogues are potential anticancer drugs due to their ability to inhibit angiogenesis. E(trans)-combretastatins are considerably less active than the Z(cis)-combretastatins proposed for clinical use. However the E-combretastatins exhibit stronger intrinsic fluorescence with quantum yields and lifetimes that depend markedly on solvent polarity and viscosity. It is proposed that 2PE in the red and near-infrared tissue window may allow in situ isomerization of E-combretastatins to the more active Z-isomer, offering spatial and temporal control of drug activation and constitute a novel form of photodynamic therapy. In the present work we have characterised 2PE of E-CA4 and have used fluorescence lifetime imaging with 2PE to study uptake and intracellular disposition of E-CA4 and an analogue. The results show that these molecules accumulate rapidly in cells and are located mainly in lipidic environments such as lipid droplets. Within the droplets the local concentrations may be up to two orders of magnitude higher than that of the drug in the surrounding medium.
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Affiliation(s)
- Roger H Bisby
- School of Environment and Life Sciences, University of Salford, Salford M5 4WT, UK.
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14
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Ohla S, Beyreiss R, Fritzsche S, Glaser P, Nagl S, Stockhausen K, Schneider C, Belder D. Monitoring On-Chip Pictet-Spengler Reactions by Integrated Analytical Separation and Label-Free Time-Resolved Fluorescence. Chemistry 2011; 18:1240-6. [DOI: 10.1002/chem.201101768] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 09/08/2011] [Indexed: 02/06/2023]
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15
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Leeder JM, Andrews DL. A molecular theory for two-photon and three-photon fluorescence polarization. J Chem Phys 2011; 134:094503. [PMID: 21384981 DOI: 10.1063/1.3556537] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In the analysis of molecular structure and local order in heterogeneous samples, multiphoton excitation of fluorescence affords chemically specific information and high-resolution imaging. This report presents the results of an investigation that secures a detailed theoretical representation of the fluorescence polarization produced by one-, two-, and three-photon excitations, with orientational averaging procedures being deployed to deliver the fully disordered limits. The equations determining multiphoton fluorescence response prove to be expressible in a relatively simple, generic form, and graphs exhibit the functional form of the multiphoton fluorescence polarization. Amongst other features, the results lead to the identification of a condition under which the fluorescence produced through the concerted absorption of any number of photons becomes completely unpolarized. It is also shown that the angular variation of fluorescence intensities is reliable indicator of orientational disorder.
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Affiliation(s)
- J M Leeder
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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16
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Li C, Pastila RK, Pitsillides C, Runnels JM, Puoris'haag M, Côté D, Lin CP. Imaging leukocyte trafficking in vivo with two-photon-excited endogenous tryptophan fluorescence. OPTICS EXPRESS 2010; 18:988-99. [PMID: 20173920 PMCID: PMC3369551 DOI: 10.1364/oe.18.000988] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We describe a new method for imaging leukocytes in vivo by exciting the endogenous protein fluorescence in the ultraviolet (UV) spectral region where tryptophan is the major fluorophore. Two-photon excitation near 590 nm allows noninvasive optical sectioning through the epidermal cell layers into the dermis of mouse skin, where leukocytes can be observed by video-rate microscopy to interact dynamically with the dermal vascular endothelium. Inflammation significantly enhances leukocyte rolling, adhesion, and tissue infiltration. After exiting the vasculature, leukocytes continue to move actively in tissue as observed by time-lapse microscopy, and are distinguishable from resident autofluorescent cells that are not motile. Because the new method alleviates the need to introduce exogenous labels, it is potentially applicable for tracking leukocytes and monitoring inflammatory cellular reactions in humans.
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Affiliation(s)
- Chunqiang Li
- Wellman Center for Photomedicine and Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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17
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Sahoo B, Balaji J, Nag S, Kaushalya SK, Maiti S. Protein aggregation probed by two-photon fluorescence correlation spectroscopy of native tryptophan. J Chem Phys 2009; 129:075103. [PMID: 19044804 DOI: 10.1063/1.2969110] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Fluorescence correlation spectroscopy (FCS) has proven to be a powerful tool for the study of a range of biophysical problems including protein aggregation. However, the requirement of fluorescent labeling has been a major drawback of this approach. Here we show that the intrinsic tryptophan fluorescence, excited via a two-photon mechanism, can be effectively used to study the aggregation of tryptophan containing proteins by FCS. This method can also yield the tryptophan fluorescence lifetime in parallel, which provides a complementary parameter to understand the aggregation process. We demonstrate that the formation of soluble aggregates of barstar at pH 3.5 shows clear signatures both in the two-photon tryptophan FCS data and in the tryptophan lifetime analysis. The ability to probe the soluble aggregates of unmodified proteins is significant, given the major role played by this species in amyloid toxicity.
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Affiliation(s)
- Bankanidhi Sahoo
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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18
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Guo FQ, Sun XL, Liang H, Hu ZY, Zhang QJ, Ming H. Spectroscopic Properties and Three-photon Absorption Induced Optical Limiting of Series of Novel Nonlinear Chromophores. CHINESE J CHEM PHYS 2008. [DOI: 10.1088/1674-0068/21/03/227-232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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19
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Basu B, Desai R, Balaji J, Chaerkady R, Sriram V, Maiti S, Panicker MM. Serotonin in pre-implantation mouse embryos is localized to the mitochondria and can modulate mitochondrial potential. Reproduction 2008; 135:657-69. [PMID: 18304982 DOI: 10.1530/rep-07-0577] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Serotonin is reported to be present in early embryos of many species and plays an important role in early patterning. Since it is a fluorophore, it can be directly visualized using fluorescence microscopy. Here, we use three-photon microscopy to image serotonin in live pre-implantation mouse embryos. We find that it is present as puncta averaging 1.3 square microns and in concentrations as high as 442 mM. The observed serotonin puncta were found to co-localize with mitochondria. Live embryos pre-incubated with serotonin showed a higher mitochondrial potential, indicating that it can modulate mitochondrial potential. Pre-implantation mouse embryos were also examined at various developmental stages for the presence of transcripts of the peripheral and neuronal forms of tryptophan hydroxylase (Tph1 and Tph2 respectively) and the classical serotonin transporter (Slc6a4). Transcripts of Tph2 were seen in oocytes and in two-cell stages, whereas transcripts of Tph1 were not detected at any stage. Transcripts of the transporter, Slc6a4, were present in all pre-implantation stages investigated. These results suggest that serotonin in embryos can arise from a combination of synthesis and uptake from the surrounding milieu.
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Affiliation(s)
- Basudha Basu
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, UAS-GKVK Campus, Bellary Road, Bangalore 560065, India.
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20
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Botchway SW, Parker AW, Bisby RH, Crisostomo AG. Real-time cellular uptake of serotonin using fluorescence lifetime imaging with two-photon excitation. Microsc Res Tech 2008; 71:267-73. [DOI: 10.1002/jemt.20548] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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21
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Balaji J, Desai R, Kaushalya SK, Eaton MJ, Maiti S. Quantitative measurement of serotonin synthesis and sequestration in individual live neuronal cells. J Neurochem 2005; 95:1217-26. [PMID: 16269014 DOI: 10.1111/j.1471-4159.2005.03489.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Synthesis and subsequent sequestration into vesicles are essential steps that precede neurotransmitter exocytosis, but neither the total neurotransmitter content nor the fraction sequestered into vesicles have been measured in individual live neurons. We use multiphoton microscopy to directly observe intracellular and intravesicular serotonin in the serotonergic neuronal cell line RN46A. We focus on how the relationship between synthesis and sequestration changes as synthesis is up-regulated by differentiation or down-regulated by chemical inhibition. Temperature-induced differentiation causes an increase of about 60% in the total serotonin content of individual cells, which goes up to about 10 fmol. However, the number of vesicles per cell increases by a factor of four and the proportion of serotonin sequestered inside the vesicles increases by a factor of five. When serotonin synthesis is inhibited in differentiated cells and the serotonin content goes down to the level present in undifferentiated cells, the sequestered proportion still remains at this high level. The total neurotransmitter content of a cell is, thus, an unreliable indicator of the sequestered amount.
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Affiliation(s)
- J Balaji
- Tata Institute of Fundamental Research, Mumbai, India
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