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Page EF, Blake MJ, Foley GA, Calhoun TR. Monitoring membranes: The exploration of biological bilayers with second harmonic generation. CHEMICAL PHYSICS REVIEWS 2022; 3:041307. [PMID: 36536669 PMCID: PMC9756348 DOI: 10.1063/5.0120888] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 11/03/2022] [Indexed: 12/23/2022]
Abstract
Nature's seemingly controlled chaos in heterogeneous two-dimensional cell membranes stands in stark contrast to the precise, often homogeneous, environment in an experimentalist's flask or carefully designed material system. Yet cell membranes can play a direct role, or serve as inspiration, in all fields of biology, chemistry, physics, and engineering. Our understanding of these ubiquitous structures continues to evolve despite over a century of study largely driven by the application of new technologies. Here, we review the insight afforded by second harmonic generation (SHG), a nonlinear optical technique. From potential measurements to adsorption and diffusion on both model and living systems, SHG complements existing techniques while presenting a large exploratory space for new discoveries.
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Affiliation(s)
- Eleanor F. Page
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Marea J. Blake
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Grant A. Foley
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Tessa R. Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
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2
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Szukalski A, Krawczyk P, Sahraoui B, Rosińska F, Jędrzejewska B. A Modified Oxazolone Dye Dedicated to Spectroscopy and Optoelectronics. J Org Chem 2022; 87:7319-7332. [PMID: 35588394 PMCID: PMC9171828 DOI: 10.1021/acs.joc.2c00500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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Here we present a
newly synthesized bifunctional organic chromophore
with appealing spectroscopic and nonlinear optical features. The positions
of absorption and emission maxima of the dye vary with increasing
solvent polarity and exhibit positive solvatochromism. The determined
change in the dipole moment upon excitation based on the Bilot and
Kawski theory is 5.94 D, which corresponds to the intermolecular displacement
of a charge equal to 1.24 Å. An investigated organic-based system
represents a significant, repeatable, and stable over time optical
signal modulation in the manner of the refractive index value. Its
magnitude is varied both by optical pumping intensity as well as by
external frequency modulation, which indicates that such system is
an alluring and alternative core unit for optoelectronic devices and
complex networks. Then, the same active system, due to the nonresonant
mechanism of higher harmonics of light inducement, can provide second
and third harmonic signals. According to the introduced laser
line spatial modifications (parallel or perpendicular polarization
directions), it is resulted in output SHG signal with magnitude varied
about 100%. Its magnitude is noticeably small; however, to construct
sensitive optical sensors or infrared indicators, such feature may
guarantee satisfying circumstances.
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Affiliation(s)
- Adam Szukalski
- Faculty of Chemistry, Wroclaw University of Science and Technology, Wyb. Wyspiańskiego 27, Wrocław 50-370, Poland
| | - Przemysław Krawczyk
- Faculty of Pharmacy, Nicolaus Copernicus University, Collegium Medicum, Kurpińskiego 5, Bydgoszcz 85-950, Poland
| | - Bouchta Sahraoui
- Laboratoire MOLTECH-Anjou, Université d'Angers, UFR Sciences, UMR 6200, CNRS, 2 Bd. Lavoisier, Angers Cedex 49045, France
| | - Faustyna Rosińska
- Faculty of Chemical Technology and Engineering, Bydgoszcz University of Science and Technology, Seminaryjna 3, Bydgoszcz 85-326, Poland
| | - Beata Jędrzejewska
- Faculty of Chemical Technology and Engineering, Bydgoszcz University of Science and Technology, Seminaryjna 3, Bydgoszcz 85-326, Poland
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Optical second harmonic generation microscopy: application to the sensitive detection of cell membrane damage. Biophys Rev 2019; 11:399-408. [PMID: 31073956 DOI: 10.1007/s12551-019-00546-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 04/30/2019] [Indexed: 10/26/2022] Open
Abstract
Optical second harmonic generation (SHG) is a nonlinear optical process which is sensitive to the symmetry of media. SHG microscopy allows for selective probing of a non-centrosymmetric area of sample. This type of nonlinear optical microscope was first used to observe ferroelectric domains and has been applied to various specimens including the biological samples to date. Imaging of the endogenous SHG of biological tissue has been utilized for the selective observation of filament systems in tissues such as collagen, myosin, and microtubules, which exhibit a polar structure. The cellular membrane can be selectively observed by the SHG microscope through membrane staining with amphiphilic polar dye molecules. It has been reported that, by imaging exogenous SHG of the membrane, sensitive detection of membrane damage could be realized using the SHG microscope. Because the staining dye is fluorescent, both SHG and two-photon excited fluorescence (TPF) images can be obtained simultaneously. How the SHG intensity depends on the molecular alignment of the polar dye molecules that reflects the ordering of lipid molecules in the plasma membrane and the necessity of the normalization of the SHG intensity by the TPF intensity is discussed. Furthermore, the assessment of the membrane damage induced by exposing polycation to HeLa cells has been compared with the conventional cytotoxicity and cell viability tests to demonstrate the higher sensitivity of the present SHG-based assay.
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Moen EK, Ibey BL, Beier HT, Armani AM. Quantifying pulsed electric field-induced membrane nanoporation in single cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2795-2803. [PMID: 27535877 DOI: 10.1016/j.bbamem.2016.08.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/11/2016] [Accepted: 08/12/2016] [Indexed: 12/21/2022]
Abstract
Plasma membrane disruption can trigger a host of cellular activities. One commonly observed type of disruption is pore formation. Molecular dynamic (MD) simulations of simplified lipid membrane structures predict that controllably disrupting the membrane via nano-scale poration may be possible with nanosecond pulsed electric fields (nsPEF). Until recently, researchers hoping to verify this hypothesis experimentally have been limited to measuring the relatively slow process of fluorescent markers diffusing across the membrane, which is indirect evidence of nanoporation that could be channel-mediated. Leveraging recent advances in nonlinear optical microscopy, we elucidate the role of pulse parameters in nsPEF-induced membrane permeabilization in live cells. Unlike previous techniques, it is able to directly observe loss of membrane order at the onset of the pulse. We also develop a complementary theoretical model that relates increasing membrane permeabilization to membrane pore density. Due to the significantly improved spatial and temporal resolution possible with our imaging method, we are able to directly compare our experimental and theoretical results. Their agreement provides substantial evidence that nanoporation does occur and that its development is dictated by the electric field distribution.
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Affiliation(s)
- Erick K Moen
- Ming Hsieh Department of Electrical Engineering - Electrophysics, University of Southern California, 920 Bloom Walk, SSC, 502 Los Angeles, CA, USA.
| | - Bennett L Ibey
- Bioeffects Division, 711 Human Performance Wing, Air Force Research Laboratory, 4141 Petroleum Rd., JBSA Fort Sam, Houston, TX 78234, USA
| | - Hope T Beier
- Bioeffects Division, 711 Human Performance Wing, Air Force Research Laboratory, 4141 Petroleum Rd., JBSA Fort Sam, Houston, TX 78234, USA
| | - Andrea M Armani
- Ming Hsieh Department of Electrical Engineering - Electrophysics, University of Southern California, 920 Bloom Walk, SSC, 502 Los Angeles, CA, USA
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Nuriya M, Fukushima S, Momotake A, Shinotsuka T, Yasui M, Arai T. Multimodal two-photon imaging using a second harmonic generation-specific dye. Nat Commun 2016; 7:11557. [PMID: 27156702 PMCID: PMC4865818 DOI: 10.1038/ncomms11557] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 04/07/2016] [Indexed: 11/09/2022] Open
Abstract
Second harmonic generation (SHG) imaging can be used to visualize unique biological phenomena, but currently available dyes limit its application owing to the strong fluorescent signals that they generate together with SHG. Here we report the first non-fluorescent and membrane potential-sensitive SHG-active organic dye Ap3. Ap3 is photostable and generates SH signals at the plasma membrane with virtually no fluorescent signals, in sharp contrast to the previously used fluorescent dye FM4-64. When tested in neurons, Ap3-SHG shows linear membrane potential sensitivity and fast responses to action potentials, and also shows significantly reduced photodamage compared with FM4-64. The SHG-specific nature of Ap3 allows simultaneous and completely independent imaging of SHG signals and fluorescent signals from various reporter molecules, including markers of cellular organelles and intracellular calcium. Therefore, this SHG-specific dye enables true multimodal two-photon imaging in biological samples. Current dyes for second harmonic generation (SHG) imaging strongly fluoresce, limiting their application. Here the authors develop a SHG-specific dye, Ap3, that partitions into cell membranes, displays sensitivity to membrane potential and has virtually no fluorescence emission at SHG imaging wavelengths.
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Affiliation(s)
- Mutsuo Nuriya
- Department of Pharmacology School of Medicine, Keio University, 35 Shinanomachi, Tokyo 160-8582, Japan.,Graduate School of Environment and Information Sciences, Yokohama National University, Yokohama 240-8501, Japan
| | - Shun Fukushima
- Graduate School of Pure and Applied Sciences and Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), University of Tsukuba, Tsukuba 305-8577, Japan
| | - Atsuya Momotake
- Graduate School of Pure and Applied Sciences and Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), University of Tsukuba, Tsukuba 305-8577, Japan
| | - Takanori Shinotsuka
- Department of Pharmacology School of Medicine, Keio University, 35 Shinanomachi, Tokyo 160-8582, Japan
| | - Masato Yasui
- Department of Pharmacology School of Medicine, Keio University, 35 Shinanomachi, Tokyo 160-8582, Japan
| | - Tatsuo Arai
- Graduate School of Pure and Applied Sciences and Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), University of Tsukuba, Tsukuba 305-8577, Japan
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Moree B, Yin G, Lázaro DF, Munari F, Strohäker T, Giller K, Becker S, Outeiro TF, Zweckstetter M, Salafsky J. Small Molecules Detected by Second-Harmonic Generation Modulate the Conformation of Monomeric α-Synuclein and Reduce Its Aggregation in Cells. J Biol Chem 2015; 290:27582-93. [PMID: 26396193 PMCID: PMC4646010 DOI: 10.1074/jbc.m114.636027] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Indexed: 01/02/2023] Open
Abstract
Proteins are structurally dynamic molecules that perform specialized functions through unique conformational changes accessible in physiological environments. An ability to specifically and selectively control protein function via conformational modulation is an important goal for development of novel therapeutics and studies of protein mechanism in biological networks and disease. Here we applied a second-harmonic generation-based technique for studying protein conformation in solution and in real time to the intrinsically disordered, Parkinson disease related protein α-synuclein. From a fragment library, we identified small molecule modulators that bind to monomeric α-synuclein in vitro and significantly reduce α-synuclein aggregation in a neuronal cell culture model. Our results indicate that the conformation of α-synuclein is linked to the aggregation of protein in cells. They also provide support for a therapeutic strategy of targeting specific conformations of the protein to suppress or control its aggregation.
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Affiliation(s)
- Ben Moree
- From Biodesy, Inc., South San Francisco, California 94080
| | - Guowei Yin
- the Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Diana F Lázaro
- the Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center, 37075 Göttingen, Germany, the Department of Neurodegeneration and Restorative Research, University Medical Center Göttingen, 37073 Göttingen, Germany, and
| | - Francesca Munari
- the Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany, the German Center for Neurodegenerative Diseases (DZNE), 37077 Göttingen, Germany
| | - Timo Strohäker
- the Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Karin Giller
- the Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Stefan Becker
- the Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Tiago F Outeiro
- the Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center, 37075 Göttingen, Germany, the Department of Neurodegeneration and Restorative Research, University Medical Center Göttingen, 37073 Göttingen, Germany, and
| | - Markus Zweckstetter
- the Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany, the German Center for Neurodegenerative Diseases (DZNE), 37077 Göttingen, Germany
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Mishra A, Sahu S, Tripathi S, Krishnamoorthy G. Photoinduced intramolecular charge transfer in trans-2-[4'-(N,N-dimethylamino)styryl]imidazo[4,5-b]pyridine: effect of introducing a C[double bond, length as m-dash]C double bond. Photochem Photobiol Sci 2015; 13:1476-86. [PMID: 25103414 DOI: 10.1039/c4pp00237g] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The spectral characteristics of trans-2-[4'-(N,N-dimethylamino)styryl]imidazo[4,5-b]pyridine (t-DMASIP-b) have been investigated using absorption and fluorescence techniques, and compared with 2-(4'-N,N-dimethylamino)imidazo[4,5-b]pyridine (DMAPIP-b). The study reveals that introduction of a C[double bond, length as m-dash]C double bond strongly perturbs the photophysics of the system. Unlike DMAPIP-b, t-DMASIP-b emits a single emission in aprotic and protic solvents. The emission occurs from the locally excited state in nonpolar solvents and from a planar intramolecular charge transfer (PICT) state in polar solvents. Multiple linear regression analysis suggests that among the different solvent parameters, the dipolar interaction contributes more to the stabilization of the system in both the ground and excited states. Theoretical calculations suggest that, unlike in DMAPIP-b, proton coupled twisted intramolecular charge transfer (TICT) emission does not occur in t-DMASIP-b. The higher quantum yield obtained in the viscous solvent glycerol is attributed to the restriction of the twisting of the olefinic bond. The photoirradiation of t-DMASIP-b shows that isomerization takes place in all solvents, including viscous glycerol. The theoretically simulated potential energy surface shows that isomerization occurs via a phantom state, which is a nonradiative process. The rise in temperature favors the photoisomerization, thus, the fluorescence quantum yield decreases. The prototropic study indicates that, unlike in DMAPIP-b, the protonation takes place at different places to form the monocations.
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Affiliation(s)
- Anasuya Mishra
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
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8
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Loew LM, Lewis A. Second Harmonic Imaging of Membrane Potential. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:473-92. [PMID: 26238065 DOI: 10.1007/978-3-319-17641-3_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The non-linear optical effect known as second harmonic generation (SHG) has been recognized since the earliest days of the laser. But it has only been in the last 20 years that it has begun to emerge as a viable microscope imaging contrast mechanism for visualization of cell and tissue structure and function. This is because only small modifications are required to equip a standard laser scanning 2-photon microscope for second harmonic imaging microscopy (SHIM). SHG signals from certain membrane-bound dyes are highly sensitive to membrane potential, indicating that SHIM may become a valuable probe of cell physiology. However, for the current generation of dyes and microscopes, the small signal size limits the number of photons that can be collected during the course of a fast action potential. Better dyes and optimized microscope optics could ultimately lead to the ability to image neuronal electrical activity with SHIM.
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Affiliation(s)
- Leslie M Loew
- Department of Cell Biology, R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT, 06030-1507, USA,
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Fisher JAN, Salzberg BM. Two-Photon Excitation of Fluorescent Voltage-Sensitive Dyes: Monitoring Membrane Potential in the Infrared. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:427-53. [PMID: 26238063 DOI: 10.1007/978-3-319-17641-3_17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Functional imaging microscopy based on voltage-sensitive dyes (VSDs) has proven effective for revealing spatio-temporal patterns of activity in vivo and in vitro. Microscopy based on two-photon excitation of fluorescent VSDs offers the possibility of recording sub-millisecond membrane potential changes on micron length scales in cells that lie upwards of one millimeter below the brain's surface. Here we describe progress in monitoring membrane voltage using two-photon excitation (TPE) of VSD fluorescence, and detail an application of this emerging technology in which action potentials were recorded in single trials from individual mammalian nerve terminals in situ. Prospects for, and limitations of this method are reviewed.
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10
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Jinno Y, Shoda K, Rial-Verde E, Yuste R, Miyawaki A, Tsutsui H. Engineering a genetically-encoded SHG chromophore by electrostatic targeting to the membrane. Front Mol Neurosci 2014; 7:93. [PMID: 25505870 PMCID: PMC4245886 DOI: 10.3389/fnmol.2014.00093] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 11/08/2014] [Indexed: 11/22/2022] Open
Abstract
Although second harmonic generation (SHG) microscopy provides unique imaging advantages for voltage imaging and other biological applications, genetically-encoded SHG chromophores remain relatively unexplored. SHG only arises from non-centrosymmetric media, so an anisotropic arrangement of chromophores is essential to provide strong SHG signals. Here, inspired by the mechanism by which K-Ras4B associates with plasma membranes, we sought to achieve asymmetric arrangements of chromophores at the membrane-cytoplasm interface using the fluorescent protein mVenus. After adding a farnesylation motif to the C-terminus of mVenus, nine amino acids composing its β-barrel surface were replaced by lysine, forming an electrostatic patch. This protein (mVe9Knus-CVIM) was efficiently targeted to the plasma membrane in a geometrically defined manner and exhibited SHG in HEK293 cells. In agreement with its design, mVe9Knus-CVIM hyperpolarizability was oriented at a small angle (~7.3°) from the membrane normal. Genetically-encoded SHG chromophores could serve as a molecular platform for imaging membrane potential.
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Affiliation(s)
- Yuka Jinno
- Laboratory of Integrative Physiology, Graduate School of Medicine, Osaka University Suita, Japan
| | - Keiko Shoda
- Laboratory for Cell Function Dynamics, Brain Science Institute, RIKEN Wako, Japan
| | - Emiliano Rial-Verde
- Department of Biological Sciences, Neurotechnology Center, Columbia University New York, NY, USA
| | - Rafael Yuste
- Department of Biological Sciences, Neurotechnology Center, Columbia University New York, NY, USA
| | - Atsushi Miyawaki
- Laboratory for Cell Function Dynamics, Brain Science Institute, RIKEN Wako, Japan
| | - Hidekazu Tsutsui
- Laboratory for Cell Function Dynamics, Brain Science Institute, RIKEN Wako, Japan ; Formation of and Information Processing by Neural Networks, and Control, PRESTO, Japan Science and Technology Agency (JST) Kawaguchi, Japan ; Department of Material Science, Japan Advanced Institute of Science and Technology Nomi, Japan
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Reeve JE, Corbett AD, Boczarow I, Kaluza W, Barford W, Bayley H, Wilson T, Anderson HL. Porphyrins for Probing Electrical Potential Across Lipid Bilayer Membranes by Second Harmonic Generation. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201304515] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Reeve JE, Corbett AD, Boczarow I, Kaluza W, Barford W, Bayley H, Wilson T, Anderson HL. Porphyrins for probing electrical potential across lipid bilayer membranes by second harmonic generation. Angew Chem Int Ed Engl 2013; 52:9044-8. [PMID: 23861287 PMCID: PMC3881515 DOI: 10.1002/anie.201304515] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Indexed: 11/08/2022]
Affiliation(s)
- James E Reeve
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
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Probing the orientational distribution of dyes in membranes through multiphoton microscopy. Biophys J 2013; 103:907-17. [PMID: 23009840 DOI: 10.1016/j.bpj.2012.08.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 07/23/2012] [Accepted: 08/01/2012] [Indexed: 11/21/2022] Open
Abstract
Numerous dyes are available or under development for probing the structural and functional properties of biological membranes. Exogenous chromophores adopt a range of orientations when bound to membranes, which have a drastic effect on their biophysical behavior. Here, we present a method that employs optical anisotropy data from three polarization-imaging techniques to establish the distribution of orientations adopted by molecules in monolayers and bilayers. The resulting probability density functions, which contain the preferred molecular tilt μ and distribution breadth γ, are more informative than an average tilt angle [φ]. We describe a methodology for the extraction of anisotropy data through an image-processing technology that decreases the error in polarization measurements by about a factor of four. We use this technique to compare di-4-ANEPPS and di-8-ANEPPS, both dipolar dyes, using data from polarized 1-photon, 2-photon fluorescence and second-harmonic generation imaging. We find that di-8-ANEPPS has a lower tilt but the same distributional width. We find the distribution of tilts taken by di-4-ANEPPS in two phospholipid membrane models: giant unilamellar vesicles and water-in-oil droplet monolayers. Both models result in similar distribution functions with average tilts of 52° and 47°, respectively.
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Vanzi F, Sacconi L, Cicchi R, Pavone FS. Protein conformation and molecular order probed by second-harmonic-generation microscopy. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:060901. [PMID: 22734730 DOI: 10.1117/1.jbo.17.6.060901] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Second-harmonic-generation (SHG) microscopy has emerged as a powerful tool to image unstained living tissues and probe their molecular and supramolecular organization. In this article, we review the physical basis of SHG, highlighting how coherent summation of second-harmonic response leads to the sensitivity of polarized SHG to the three-dimensional distribution of emitters within the focal volume. Based on the physical description of the process, we examine experimental applications for probing the molecular organization within a tissue and its alterations in response to different biomedically relevant conditions. We also describe the approach for obtaining information on molecular conformation based on SHG polarization anisotropy measurements and its application to the study of myosin conformation in different physiological states of muscle. The capability of coupling the advantages of nonlinear microscopy (micrometer-scale resolution in deep tissue) with tools for probing molecular structure in vivo renders SHG microscopy an extremely powerful tool for the advancement of biomedical optics, with particular regard to novel technologies for molecular diagnostic in vivo.
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Affiliation(s)
- Francesco Vanzi
- University of Florence, Department of Evolutionary Biology Leo Pardi, Florence, Italy
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15
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Hajj B, Perruchas S, Lautru J, Dantelle G, Gacoin T, Zyss J, Chauvat D. Electro-optical Pockels scattering from a single nanocrystal. OPTICS EXPRESS 2011; 19:9000-9007. [PMID: 21643153 DOI: 10.1364/oe.19.009000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The electro-optical Pockels response from a single non-centrosymmetric nanocrystal is reported. High sensitivity to the weak electric-field dependent nonlinear scattering is achieved through a dedicated imaging interferometric microscope and the linear dependence of electro-optical signal upon the applied field is checked. Using different incident light polarization states, a priori random spatial orientation of the crystal can be inferred. The electro-optical response from a nanocrystal provides local subwavelength sensor of quasi-static electric fields with potential applications in physics and biology. It also leads to a new sub-wavelength microscopy towards the nanoscale investigation of interesting phenomena such as nanoferroelectricity.
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Affiliation(s)
- Bassam Hajj
- Laboratoire de photonique quantique et moléculaire, D’Alembert Institute, Ecole Normale Supérieure de Cachan, 61 Avenue du Président Wilson, 94230 Cachan, France.
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16
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Voronin AA, Fedotov IV, Doronina-Amitonova LV, Ivashkina OI, Zots MA, Fedotov AB, Anokhin KV, Zheltikov AM. Ionization penalty in nonlinear Raman neuroimaging. OPTICS LETTERS 2011; 36:508-510. [PMID: 21326438 DOI: 10.1364/ol.36.000508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Light-assisted ionization accompanying coherent anti-Stokes Raman scattering (CARS) of ultrashort laser pulses in brain tissue is shown to manifest itself in a detectable blueshift of the anti-Stokes signal. This blueshift can serve as an indicator of ionization processes in CARS-based neuroimaging.
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Affiliation(s)
- Aleksandr A Voronin
- Physics Department, International Laser Center, M V Lomonosov Moscow State University, Moscow, Russia
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17
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Rama S, Vetrivel L, Semyanov A. Second-harmonic generation voltage imaging at subcellular resolution in rat hippocampal slices. JOURNAL OF BIOPHOTONICS 2010; 3:784-790. [PMID: 20815024 DOI: 10.1002/jbio.201000073] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Action potential (AP) is a major signaling mechanism in the neuronal networks. Dendritic AP propagation is important for information processing within the individual neurons. Due to limitations of electrode-based techniques most research on subcellular AP propagation has been restricted to soma and proximal parts of the primary dendrites. Development of voltage-sensitive dyes (VSD) has opened up a possibility to measure voltage changes in the oblique dendrites and the spines. Membrane-bound organic VSD can be used both for fluorescent imaging and imaging of second-harmonic generation (SHG). Both phenomena are voltage dependent and can be used for measuring membrane potential changes. However, changes in SHG are linear to the change in the local membrane potential and its slope is constant across different compartments of cells. Although SHG demonstrates reasonable change with membrane voltage (over 10% per 100 mV), the signal-to-noise (S/N) ratio is currently lower in SHG measurement than in fluorescent methods.
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Affiliation(s)
- Sylvain Rama
- RIKEN Brain Science Institute BSI, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
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Shneider MN, Voronin AA, Zheltikov AM. Action-potential-encoded second-harmonic generation as an ultrafast local probe for nonintrusive membrane diagnostics. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:031926. [PMID: 20365789 DOI: 10.1103/physreve.81.031926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 12/24/2009] [Indexed: 05/29/2023]
Abstract
The Hodgkin-Huxley treatment of the dynamics of a nerve impulse on a cell membrane is combined with a phenomenological description of molecular hyperpolarizabilities to develop a closed-form model of an action-potential-sensitive second-harmonic response of membrane-bound chromophores. This model is employed to understand the key properties of the map between the action potential and modulation of the second harmonic from a cell membrane stained with hyperpolarizable chromophore molecules.
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Affiliation(s)
- M N Shneider
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544-5263, USA
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19
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Electro-optical imaging microscopy of dye-doped artificial lipidic membranes. Biophys J 2009; 97:2913-21. [PMID: 19948120 DOI: 10.1016/j.bpj.2009.08.055] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 07/16/2009] [Accepted: 08/17/2009] [Indexed: 11/21/2022] Open
Abstract
Artificial lipidic bilayers are widely used as a model for the lipid matrix in biological cell membranes. We use the Pockels electro-optical effect to investigate the properties of an artificial lipidic membrane doped with nonlinear molecules in the outer layer. We report here what is believed to be the first electro-optical Pockels signal and image from such a membrane. The electro-optical dephasing distribution within the membrane is imaged and the signal is shown to be linear as a function of the applied voltage. A theoretical analysis taking into account the statistical orientation distribution of the inserted dye molecules allows us to estimate the doped membrane nonlinearity. Ongoing extensions of this work to living cell membranes are discussed.
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Marx CA, Harbola U, Mukamel S. Nonlinear optical spectroscopy of single, few, and many molecules; nonequilibrium Green's function QED approach. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 2008; 77:22110. [PMID: 21037933 PMCID: PMC2964889 DOI: 10.1103/physreva.77.022110] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Nonlinear optical signals from an assembly of N noninteracting particles consist of an incoherent and a coherent component, whose magnitudes scale ~ N and ~ N(N - 1), respectively. A unified microscopic description of both types of signals is developed using a quantum electrodynamical (QED) treatment of the optical fields. Closed nonequilibrium Green's function expressions are derived that incorporate both stimulated and spontaneous processes. General (n + 1)-wave mixing experiments are discussed as an example of spontaneously generated signals. When performed on a single particle, such signals cannot be expressed in terms of the nth order polarization, as predicted by the semiclassical theory. Stimulated processes are shown to be purely incoherent in nature. Within the QED framework, heterodyne-detected wave mixing signals are simply viewed as incoherent stimulated emission, whereas homodyne signals are generated by coherent spontaneous emission.
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Affiliation(s)
- Christoph A Marx
- Department of Chemistry, University of California, Irvine, CA 92697
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21
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Rusu CF, Lanig H, Othersen OG, Kryschi C, Clark T. Monitoring Biological Membrane-Potential Changes: A CI QM/MM Study. J Phys Chem B 2008; 112:2445-55. [DOI: 10.1021/jp075372+] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Fisher JAN, Barchi JR, Welle CG, Kim GH, Kosterin P, Obaid AL, Yodh AG, Contreras D, Salzberg BM. Two-photon excitation of potentiometric probes enables optical recording of action potentials from mammalian nerve terminals in situ. J Neurophysiol 2008; 99:1545-53. [PMID: 18171710 DOI: 10.1152/jn.00929.2007] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We report the first optical recordings of action potentials, in single trials, from one or a few (approximately 1-2 microm) mammalian nerve terminals in an intact in vitro preparation, the mouse neurohypophysis. The measurements used two-photon excitation along the "blue" edge of the two-photon absorption spectrum of di-3-ANEPPDHQ (a fluorescent voltage-sensitive naphthyl styryl-pyridinium dye), and epifluorescence detection, a configuration that is critical for noninvasive recording of electrical activity from intact brains. Single-trial recordings of action potentials exhibited signal-to-noise ratios of approximately 5:1 and fractional fluorescence changes of up to approximately 10%. This method, by virtue of its optical sectioning capability, deep tissue penetration, and efficient epifluorescence detection, offers clear advantages over linear, as well as other nonlinear optical techniques used to monitor voltage changes in localized neuronal regions, and provides an alternative to invasive electrode arrays for studying neuronal systems in vivo.
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Affiliation(s)
- Jonathan A N Fisher
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6074, USA
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23
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GUALDA EJ, FILIPPIDIS G, VOGLIS G, MARI M, FOTAKIS C, TAVERNARAKIS N. In vivo imaging of cellular structures in Caenorhabditis elegans by combined TPEF, SHG and THG microscopy. J Microsc 2008; 229:141-50. [DOI: 10.1111/j.1365-2818.2007.01876.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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24
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Akemann W, Laage D, Plaza P, Martin MM, Blanchard-Desce M. Photoinduced intramolecular charge transfer in push-pull polyenes: effects of solvation, electron-donor group, and polyenic chain length. J Phys Chem B 2007; 112:358-68. [PMID: 17997542 DOI: 10.1021/jp075418z] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Subpicosecond absorption spectroscopy is used to characterize the primary photoinduced processes in a class of push-pull polyenes bearing a julolidine end group as the electron donor and a diethylthiobarbituric acid end group as the electron acceptor. The excited-state decay time and relaxation pathway have been studied for four polyenes of increasing chain length (n = 2-5 double bonds) in aprotic solvents of different solvation time, polarity, and viscosity. Intramolecular charge transfer (ICT) leading to a transient state of cyanine-like structure (fully conjugated with no bond length alternation) is observed in all polar solvents at a solvent dependent rate, but the reaction is not observed in cyclohexane, a nonpolar solvent. In polar solvents, the reaction time increases with the average solvation time but remains slightly larger, except in the viscous solvent triacetin. These facts are interpreted as an indication that both solvent reorganization and internal restructuring are involved in the ICT-state formation. The observed photodynamics resemble those we previously found for another class of polyenes bearing a dibutylaniline group as the donor, including a similar charge-transfer rate in spite of the larger electron donor character of the julolidine group. This observation brings further support to the proposal that an intramolecular coordinate is involved in the charge-transfer reaction, possibly a torsional motion of the donor end group. On the other hand, relaxation of the ICT state leads to cis-trans isomerization or crossing to the triplet state, depending on the length of the polyenic chain. In dioxane, tetrahydrofuran, and triacetin, the ICT state of the shorter chains (n = 2, 3) relaxes to the isomer with a viscosity-dependent rate, while that of the longer ones (n = 4, 5) leads to the triplet state with a viscosity-independent rate, as expected. In acetonitrile, the ICT-state lifetime is generally much shorter. A change from photoisomerization to intersystem crossing at n = 4 is also proposed in this solvent, but the formation of a photoproduct at n = 2 is not clear. In cyclohexane, where the ICT state is not formed, the relaxation pathway of the initially excited state is found to lead to an isomer for n = 2. As in polar solvents, a change to intersystem crossing at n = 4 is proposed. The direct relaxation to the ground state found at n = 3 for the series bearing a dibutylaniline group is not observed with the julolidine group. The results clearly illustrate that photoinduced reaction trajectories in push-pull polyenes are controlled by the static and dynamic properties of the solvent, the chemical nature and size of the end groups, and the conjugated-chain length and flexibility.
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Affiliation(s)
- Walther Akemann
- UMR CNRS 8640, Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France
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25
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Jiang J, Eisenthal KB, Yuste R. Second harmonic generation in neurons: electro-optic mechanism of membrane potential sensitivity. Biophys J 2007; 93:L26-8. [PMID: 17604312 PMCID: PMC1948066 DOI: 10.1529/biophysj.107.111021] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Second harmonic generation (SHG) from membrane-bound chromophores can be used to image membrane potential in neurons. We investigate the biophysical mechanism responsible for the SHG voltage sensitivity of the styryl dye FM 4-64 in pyramidal neurons from mouse neocortical slices. SHG signals are exquisitely sensitive to the polarization of the incident laser light. Using this polarization sensitivity in two complementary approaches, we estimate a approximately 36 degrees tilt angle of the chromophore to the membrane normal. Changes in membrane potential do not affect the polarization of the SHG signal. The voltage response of FM 4-64 is faster than 1 ms and does not reverse sign when imaged at either side of its absorption peak. We conclude that FM 4-64 senses membrane potential through an electro-optic mechanism, without significant chromophore membrane reorientation, redistribution, or spectral shift.
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Affiliation(s)
- Jiang Jiang
- Howard Hughes Medical Institute, Department of Biological Sciences, Columbia University, New York, NY, USA
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26
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Barsu C, Fortrie R, Nowika K, Baldeck PL, Vial JC, Barsella A, Fort A, Hissler M, Bretonnière Y, Maury O, Andraud C. Synthesis of chromophores combining second harmonic generation and two photon induced fluorescence properties. Chem Commun (Camb) 2006:4744-6. [PMID: 17109056 DOI: 10.1039/b610557b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The design of new chromophores presenting simultaneous SHG and TPEF properties is reported.
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Affiliation(s)
- Cyril Barsu
- Chimie pour l'optique, Laboratoire de chimie, UMR CNRS-ENS-Lyon 5182, 46 Allée d'Italie, F-69364 Lyon cedex 07, France
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27
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Oheim M, Michael DJ, Geisbauer M, Madsen D, Chow RH. Principles of two-photon excitation fluorescence microscopy and other nonlinear imaging approaches. Adv Drug Deliv Rev 2006; 58:788-808. [PMID: 17055106 DOI: 10.1016/j.addr.2006.07.005] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Accepted: 07/13/2006] [Indexed: 11/19/2022]
Abstract
The aim of this article is to review the basic principles of two-photon excitation fluorescence (2PEF) microscopy and to compare the advantages and disadvantages of 2PEF imaging to other microscopy methodologies. 2PEF imaging is a nonlinear approach that generates images of optical sections and that is particularly well suited for deep-tissue and in vivo imaging of live animals. The nonlinear excitation used for 2PEF offers the advantage, too, of being able to generate contrast from second or third harmonic generation as well as coherent anti-Stokes Raman scattering. We also review the recent use of nonlinear excitation to provide image resolution beyond the diffraction limit and discuss the progress in non-scanning (planar) 2PEF microscopy, an approach that holds great potential for large-scale quantitative imaging and plate reading, e.g., in screening applications.
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Affiliation(s)
- Martin Oheim
- Molecular and cellular Biophysics of the Synapse, INSERM U603, F-75006 Paris, France.
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28
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29
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Sacconi L, Dombeck DA, Webb WW. Overcoming photodamage in second-harmonic generation microscopy: real-time optical recording of neuronal action potentials. Proc Natl Acad Sci U S A 2006; 103:3124-9. [PMID: 16488972 PMCID: PMC1413939 DOI: 10.1073/pnas.0511338103] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Second-harmonic generation (SHG) has proven essential for the highest-resolution optical recording of membrane potential (Vm) in intact specimens. Here, we demonstrate single-trial SHG recordings of neuronal somatic action potentials and quantitative recordings of their decay with averaging at multiple sites during propagation along branched neurites at distances up to 350 mum from the soma. We realized these advances by quantifying, analyzing, and thereby minimizing the dynamics of photodamage (PD), a frequent limiting factor in the optical imaging of biological preparations. The optical signal and the PD during SHG imaging of stained cultured Aplysia neurons were examined with intracellular electrode recordings monitoring the resting Vm variations induced by laser-scanning illumination. We found that the PD increased linearly with the dye concentration but grew with the cube of illumination intensity, leading to unanticipated optimization procedures to minimize PD. The addition of appropriate antioxidants in conjunction with an observed Vm recovery after termination of laser scanning further refined the imaging criteria for minimization and control of PD during SHG recording of action potentials. With these advances, the potential of SHG as an effective optical tool for neuroscience investigations is being realized.
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Affiliation(s)
- L. Sacconi
- *School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853; and
- European Laboratory for Nonlinear Spectroscopy, University of Florence, 50019 Sesto Fiorentino, Italy
| | - D. A. Dombeck
- *School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853; and
| | - W. W. Webb
- *School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853; and
- To whom correspondence should be addressed. E-mail:
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30
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Millard AC, Jin L, Wuskell JP, Boudreau DM, Lewis A, Loew LM. Wavelength- and Time-Dependence of Potentiometric Non-linear Optical Signals from Styryl Dyes. J Membr Biol 2005; 208:103-11. [PMID: 16645740 DOI: 10.1007/s00232-005-0823-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Indexed: 11/27/2022]
Abstract
Second harmonic generation (SHG) imaging microscopy is an important emerging technique for biological research, complementing existing one- and two-photon fluorescence (2PF) methods. A non-linear phenomenon employing light from mode-locked Ti:sapphire or fiber-based lasers, SHG results in intrinsic optical sectioning without the need for a confocal aperture. Furthermore, as a second-order process SHG is confined to loci lacking a center of symmetry, a constraint that is readily satisfied by lipid membranes with only one leaflet stained by a dye. Of particular interest is "resonance-enhanced" SHG from styryl dyes in cellular membranes and the possibility that SHG is sensitive to transmembrane potential. We have previously confirmed this, using simultaneous voltage-clamping and non-linear imaging of cells to find that SHG is up to four times more sensitive to potential than fluorescence. In this work, we have extended these results in two directions. First, with a range of wavelengths available from a mode-locked Ti:sapphire laser and a fiber-based laser, we have more fully investigated SHG and 2PF voltage-sensitivity from ANEP and ASTAP chromophores, obtaining SHG sensitivity spectra that are consistent with resonance enhancements. Second, we have modified our system to coordinate the application of voltage-clamp steps with non-linear image acquisition to more precisely characterize the time dependence of SHG and 2PF voltage sensitivity, finding that, at least for some dyes, SHG responds more slowly than fluorescence to changes in transmembrane potential.
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Affiliation(s)
- A C Millard
- Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, 06030, USA
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31
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Dombeck DA, Sacconi L, Blanchard-Desce M, Webb WW. Optical recording of fast neuronal membrane potential transients in acute mammalian brain slices by second-harmonic generation microscopy. J Neurophysiol 2005; 94:3628-36. [PMID: 16093337 DOI: 10.1152/jn.00416.2005] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although nonlinear microscopy and fast (approximately 1 ms) membrane potential (Vm) recording have proven valuable for neuroscience applications, their potentially powerful combination has not yet been shown for studies of Vm activity deep in intact tissue. We show that laser illumination of neurons in acute rat brain slices intracellularly filled with FM4-64 dye generates an intense second-harmonic generation (SHG) signal from somatic and dendritic plasma membranes with high contrast >125 microm below the slice surface. The SHG signal provides a linear response to DeltaVm of approximately 7.5%/100 mV. By averaging repeated line scans (approximately 50), we show the ability to record action potentials (APs) optically with a signal-to-noise ratio (S/N) of approximately 7-8. We also show recording of fast Vm steps from the dendritic arbor at depths inaccessible with previous methods. The high membrane contrast and linear response of SHG to DeltaVm provides the advantage that signal changes are not degraded by background and can be directly quantified in terms of DeltaVm. Experimental comparison of SHG and two-photon fluorescence Vm recording with the best known probes for each showed that the SHG technique is superior for Vm recording in brain slice applications, with FM4-64 as the best tested SHG Vm probe.
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Affiliation(s)
- Daniel A Dombeck
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
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Abstract
Nonlinear microscopy, a general term that embraces any microscopy technique based on nonlinear optics, is further establishing itself as an important tool in neurobiology. Recent advances in labels, labeling techniques, and the use of native or genetically encoded contrast agents have bolstered the capacity of nonlinear microscopes to image the structure and function of not just single cells but of entire networks of cells. Along with novel strategies to image over exceptionally long durations and with increased depth penetration in living brains, these advances are opening new opportunities in neurobiology that were previously unavailable.
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Affiliation(s)
- Jerome Mertz
- Boston University, Department of Biomedical Engineering, 44 Cummington Street, Boston, Massachusetts 02215, USA.
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Filippidis G, Kouloumentas C, Voglis G, Zacharopoulou F, Papazoglou TG, Tavernarakis N. Imaging of Caenorhabditis elegans neurons by second-harmonic generation and two-photon excitation fluorescence. JOURNAL OF BIOMEDICAL OPTICS 2005; 10:024015. [PMID: 15910089 DOI: 10.1117/1.1886729] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Second-harmonic generation (SHG) and two-photon excitation fluorescence (TPEF) are relatively new and promising tools for the detailed imaging of biological samples and processes at the microscopic level. By exploiting these nonlinear phenomena phototoxicity and photobleaching effects on the specimens are reduced dramatically. The main target of this work was the development of a compact inexpensive and reliable experimental apparatus for nonlinear microscopy measurements. Femtosecond laser pulses were utilized for excitation. We achieved high-resolution imaging and mapping of Caenorhabditis elegans (C. elegans) neurons and muscular structures of the pharynx, at the microscopic level by performing SHG and TPEF measurements. By detecting nonlinear phenomena such as SHG and TPEF it is feasible to extract valuable information concerning the structure and the function of nematode neurons.
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Affiliation(s)
- George Filippidis
- Foundation of Research and Technology-Hellas, Institute of Electronic Structure and Laser, PO Box 1527, Heraklion, Greece 71110.
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Sacconi L, D'Amico M, Vanzi F, Biagiotti T, Antolini R, Olivotto M, Pavone FS. Second-harmonic generation sensitivity to transmembrane potential in normal and tumor cells. JOURNAL OF BIOMEDICAL OPTICS 2005; 10:024014. [PMID: 15910088 DOI: 10.1117/1.1895205] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Second-harmonic generation (SHG) is emerging as a powerful tool for the optical measurement of transmembrane potential in live cells with high sensitivity and temporal resolution. Using a patch clamp, we characterize the sensitivity of the SHG signal to transmembrane potential for the RH 237 dye in various normal and tumor cell types. SHG sensitivity shows a significant dependence on the type of cell, ranging from 10 to 17% per 100 mV. Furthermore, in the samples studied, tumor cell lines display a higher sensitivity compared to normal cells. In particular, the SHG sensitivity increases in the cell line Balb/c3T3 by the transformation induced with SV40 infection of the cells. We also demonstrate that fluorescent labeling of the membrane with RH 237 at the concentration used for SHG measurements does not induce any measurable alteration in the electrophysiological properties of the cells investigated. Therefore, SHG is suitable for the investigation of outstanding questions in electrophysiology and neurobiology.
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Affiliation(s)
- L Sacconi
- University of Trento, Department of Physics, via Sommarive 14, I-38050 Povo, Trento, Italy
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35
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Millard AC, Jin L, Wei MD, Wuskell JP, Lewis A, Loew LM. Sensitivity of second harmonic generation from styryl dyes to transmembrane potential. Biophys J 2004; 86:1169-76. [PMID: 14747351 PMCID: PMC1303909 DOI: 10.1016/s0006-3495(04)74191-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
In this article we present results from the simultaneous nonlinear (second harmonic generation and two-photon excitation fluorescence) imaging and voltage clamping of living cells. Specifically, we determine the sensitivity to transmembrane potential of second harmonic generation by ANEP-chromophore styryl dyes as a function of excitation wavelength and dye structure. We have measured second harmonic sensitivities of up to 43% per 100 mV, more than a factor of four better than the nominal voltage sensitivity of the dyes under "one-photon" fluorescence. We find a dependence of voltage sensitivity on excitation wavelength that is consistent with a two-photon resonance, and there is a significant dependence of voltage sensitivity on the structure of the nonchromophore portion of the dyes.
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Affiliation(s)
- Andrew C Millard
- Department of Physiology and Center for Biomedical Imaging Technology, University of Connecticut Health Center, Farmington, Connecticut 06030-1507, USA
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36
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Nemet BA, Nikolenko V, Yuste R. Second harmonic imaging of membrane potential of neurons with retinal. JOURNAL OF BIOMEDICAL OPTICS 2004; 9:873-81. [PMID: 15447008 DOI: 10.1117/1.1783353] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We present a method to optically measure and image the membrane potential of neurons, using the nonlinear optical phenomenon of second harmonic generation (SHG) with a photopigment retinal as the chromophore [second harmonic retinal imaging of membrane potential (SHRIMP)]. We show that all-trans retinal, when adsorbed to the plasma membrane of living cells, can report on the local electric field via its change in SHG. Using a scanning mode-locked Ti-sapphire laser, we collect simultaneous two-photon excited fluorescence (TPEF) and SHG images of retinal-stained kidney cells and cultured pyramidal neurons. Patch clamp experiments on neurons stained with retinal show an increase of 25% in SHG intensity per 100-mV depolarization. Our data are the first demonstration of optical measurements of membrane potential of mammalian neurons with SHG. SHRIMP could have wide applicability in neuroscience and, by modifying rhodopsin, could in principle be subject for developing genetically engineered voltage sensors.
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Affiliation(s)
- Boaz A Nemet
- Columbia University, Department of Biological Sciences, 1212 Amsterdam Avenue, New York, New York 10027, USA.
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37
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Campagnola PJ, Loew LM. Second-harmonic imaging microscopy for visualizing biomolecular arrays in cells, tissues and organisms. Nat Biotechnol 2004; 21:1356-60. [PMID: 14595363 DOI: 10.1038/nbt894] [Citation(s) in RCA: 730] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Although the nonlinear optical effect known as second-harmonic generation (SHG) has been recognized since the earliest days of laser physics and was demonstrated through a microscope over 25 years ago, only in the past few years has it begun to emerge as a viable microscope imaging contrast mechanism for visualization of cell and tissue structure and function. Only small modifications are required to equip a standard laser-scanning two-photon microscope for second-harmonic imaging microscopy (SHIM). Recent studies of the three-dimensional in vivo structures of well-ordered protein assemblies, such as collagen, microtubules and muscle myosin, are beginning to establish SHIM as a nondestructive imaging modality that holds promise for both basic research and clinical pathology. Thus far the best signals have been obtained in a transmitted light geometry that precludes in vivo measurements on large living animals. This drawback may be addressed through improvements in the collection of SHG signals via an epi-illumination microscope configuration. In addition, SHG signals from certain membrane-bound dyes have been shown to be highly sensitive to membrane potential. Although this indicates that SHIM may become a valuable tool for probing cell physiology, the small signal size would limit the number of photons that could be collected during the course of a fast action potential. Better dyes and optimized microscope optics could ultimately lead to the imaging of neuronal electrical activity with SHIM.
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Affiliation(s)
- Paul J Campagnola
- Center for Biomedical Imaging Technology, Department of Physiology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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38
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Dombeck DA, Blanchard-Desce M, Webb WW. Optical recording of action potentials with second-harmonic generation microscopy. J Neurosci 2004; 24:999-1003. [PMID: 14749445 PMCID: PMC6729824 DOI: 10.1523/jneurosci.4840-03.2004] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Nonlinear microscopy has proven to be essential for neuroscience investigations of thick tissue preparations. However, the optical recording of fast (approximately 1 msec) cellular electrical activity has never until now been successfully combined with this imaging modality. Through the use of second-harmonic generation microscopy of primary Aplysia neurons in culture labeled with 4-[4-(dihexylamino)phenyl][ethynyl]-1-(4-sulfobutyl)pyridinium (inner salt), we optically recorded action potentials with 0.833 msec temporal and 0.6 microm spatial resolution on soma and neurite membranes. Second-harmonic generation response as a function of change in membrane potential was found to be linear with a signal change of approximately 6%/100 mV. The signal-to-noise ratio was approximately 1 for single-trace action potential recordings but was readily increased to approximately 6-7 with temporal averaging of approximately 50 scans. Photodamage was determined to be negligible by observing action potential characteristics, cellular resting potential, and gross cellular morphology during and after laser illumination. High-resolution (micrometer scale) optical recording of membrane potential activity by previous techniques has been limited to imaging depths an order of magnitude less than nonlinear methods. Because second-harmonic generation is capable of imaging up to approximately 400 microm deep into intact tissue with submicron resolution and little out-of-focus photodamage or bleaching, its ability to record fast electrical activity should prove valuable to future electrophysiology studies.
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Affiliation(s)
- Daniel A Dombeck
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
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39
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Pons T, Moreaux L, Mongin O, Blanchard-Desce M, Mertz J. Mechanisms of membrane potential sensing with second-harmonic generation microscopy. JOURNAL OF BIOMEDICAL OPTICS 2003; 8:428-431. [PMID: 12880348 DOI: 10.1117/1.1581871] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We characterize the transmembrane voltage response of a novel second-harmonic generation (SHG) marker using a screening protocol with giant unilamellar vesicles. Two mechanisms are found to contribute to the voltage response: (1) an electro-optic-induced alteration of the molecular hyperpolarizability and (2) an electric-field-induced alteration of the degree of molecular alignment. We quantify the relative weights and of these contributions and provide an upper limit to their response time, which is found to be submillisecond. The identification of two voltage response mechanisms leads to new strategies for the molecular design of membrane potential markers.
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Affiliation(s)
- Thomas Pons
- ESPCI, INSERM EPI 0002, CNRS FRE 2500, Neurophysiologie et Nouvelles Microscopies, Paris, France
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