1
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Renteria CA, Park J, Zhang C, Sorrells JE, Iyer RR, Tehrani KF, De la Cadena A, Boppart SA. Large field-of-view metabolic profiling of murine brain tissue following morphine incubation using label-free multiphoton microscopy. J Neurosci Methods 2024; 408:110171. [PMID: 38777156 DOI: 10.1016/j.jneumeth.2024.110171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 04/15/2024] [Accepted: 05/17/2024] [Indexed: 05/25/2024]
Abstract
BACKGROUND Although the effects on neural activation and glucose consumption caused by opiates such as morphine are known, the metabolic machinery underlying opioid use and misuse is not fully explored. Multiphoton microscopy (MPM) techniques have been developed for optical imaging at high spatial resolution. Despite the increased use of MPM for neural imaging, the use of intrinsic optical contrast has seen minimal use in neuroscience. NEW METHOD We present a label-free, multimodal microscopy technique for metabolic profiling of murine brain tissue following incubation with morphine sulfate (MSO4). We evaluate two- and three-photon excited autofluorescence, and second and third harmonic generation to determine meaningful intrinsic contrast mechanisms in brain tissue using simultaneous label-free, autofluorescence multi-harmonic (SLAM) microscopy. RESULTS Regional differences quantified in the cortex, caudate, and thalamus of the brain demonstrate region-specific changes to metabolic profiles measured from FAD intensity, along with brain-wide quantification. While the overall intensity of FAD signal significantly decreased after morphine incubation, this metabolic molecule accumulated near the nucleus accumbens. COMPARISON WITH EXISTING METHODS Histopathology requires tissue fixation and staining to determine cell type and morphology, lacking information about cellular metabolism. Tools such as fMRI or PET imaging have been widely used, but lack cellular resolution. SLAM microscopy obviates the need for tissue preparation, permitting immediate use and imaging of tissue with subcellular resolution in its native environment. CONCLUSIONS This study demonstrates the utility of SLAM microscopy for label-free investigations of neural metabolism, especially the intensity changes in FAD autofluorescence and structural morphology from third-harmonic generation.
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Affiliation(s)
- Carlos A Renteria
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA; Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Jaena Park
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA; Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Chi Zhang
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Janet E Sorrells
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA; Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Rishyashring R Iyer
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA; Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Kayvan F Tehrani
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Alejandro De la Cadena
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Stephen A Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA; Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL, USA; Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA; Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, IL, USA; NIH/NIBIB P41 Center for Label-free Imaging and Multiscale Biophotonics (CLIMB), University of Illinois Urbana-Champaign, Urbana, IL, USA.
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2
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Hegde KR, Ray K, Szmacinski H, Sorto S, Puche AC, Lengyel I, Thompson RB. Two-Photon Excited Fluorescence Lifetime Imaging of Tetracycline-Labeled Retinal Calcification. SENSORS (BASEL, SWITZERLAND) 2023; 23:6626. [PMID: 37514920 PMCID: PMC10386431 DOI: 10.3390/s23146626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/14/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023]
Abstract
Deposition of calcium-containing minerals such as hydroxyapatite and whitlockite in the subretinal pigment epithelial (sub-RPE) space of the retina is linked to the development of and progression to the end-stage of age-related macular degeneration (AMD). AMD is the most common eye disease causing blindness amongst the elderly in developed countries; early diagnosis is desirable, particularly to begin treatment where available. Calcification in the sub-RPE space is also directly linked to other diseases such as Pseudoxanthoma elasticum (PXE). We found that these mineral deposits could be imaged by fluorescence using tetracycline antibiotics as specific stains. Binding of tetracyclines to the minerals was accompanied by increases in fluorescence intensity and fluorescence lifetime. The lifetimes for tetracyclines differed substantially from the known background lifetime of the existing natural retinal fluorophores, suggesting that calcification could be visualized by lifetime imaging. However, the excitation wavelengths used to excite these lifetime changes were generally shorter than those approved for retinal imaging. Here, we show that tetracycline-stained drusen in post mortem human retinas may be imaged by fluorescence lifetime contrast using multiphoton (infrared) excitation. For this pilot study, ten eyes from six anonymous deceased donors (3 female, 3 male, mean age 83.7 years, range 79-97 years) were obtained with informed consent from the Maryland State Anatomy Board with ethical oversight and approval by the Institutional Review Board.
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Affiliation(s)
- Kavita R Hegde
- Department of Natural Sciences, Coppin State University, Baltimore, MD 21216, USA
| | - Krishanu Ray
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Henryk Szmacinski
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Sharon Sorto
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Adam C Puche
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Imre Lengyel
- The Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, UK
| | - Richard B Thompson
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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3
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Asido M, Hamerla C, Weber R, Horz M, Niraghatam MS, Heckel A, Burghardt I, Wachtveitl J. Ultrafast and efficient energy transfer in a one- and two-photon sensitized rhodamine-BODIPY dyad: a perspective for broadly absorbing photocages. Phys Chem Chem Phys 2022; 24:1795-1802. [PMID: 34985062 DOI: 10.1039/d1cp04528h] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In view of the demand for photoactivatable probes that operate in the visible (VIS) to near infrared (NIR) region of the spectrum, we designed a bichromophoric system based on a rhodamine fluorophore and a BODIPY photocage. Two-photon excited fluorescence (TPEF) measurements and quantum chemical calculations reveal excellent two-photon properties of the employed rhodamine derivative. Excitation of the rhodamine unit via a one- or two-photon process leads to excitation energy transfer (EET) onto the BODIPY part, which is followed by the liberation of the leaving group. Ultrafast transient absorption spectroscopy provides evidence for a highly efficient EET dynamics on a sub-500 femtosecond scale. Complementary quantum dynamical calculations using the multi-layer multiconfiguration time-dependent Hartree (ML-MCTDH) approach highlight the quantum coherent character of the EET transfer. Photorelease of p-nitroaniline (PNA) was investigated by UV/vis absorption spectroscopy by either excitation of the rhodamine or the BODIPY moiety. Even though a quantitative assessment of the PNA yield could not be achieved for this particular BODIPY cage, the present study provides a design principle for a class of photocages that can be broadly activated between 500 and 900 nm.
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Affiliation(s)
- Marvin Asido
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
| | - Carsten Hamerla
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
| | - Rebekka Weber
- Institute of Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
| | - Maximiliane Horz
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
| | - Madhava Shyam Niraghatam
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
| | - Alexander Heckel
- Institute of Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
| | - Irene Burghardt
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
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4
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Lang RT, Spring BQ. Two-photon peak molecular brightness spectra reveal long-wavelength enhancements of multiplexed imaging depth and photostability. BIOMEDICAL OPTICS EXPRESS 2021; 12:5909-5919. [PMID: 34692224 PMCID: PMC8515958 DOI: 10.1364/boe.433989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
The broad use of two-photon microscopy has been enabled in part by Ti:Sapphire femtosecond lasers, which offer a wavelength-tunable source of pulsed excitation. Action spectra have thus been primarily reported for the tunable range of Ti:Sapphire lasers (∼700-1000 nm). However, longer wavelengths offer deeper imaging in tissue via reduced scattering and spectral dips in water absorption, and new generations of pulsed lasers offer wider tunable ranges. We present the peak molecular brightness spectra for eight Alexa Fluor dyes between 700-1300 nm as a first-order surrogate for action spectra measured with an unmodified commercial microscope, which reveal overlapping long-wavelength excitation peaks with potential for multiplexed excitation. We demonstrate simultaneous single-wavelength excitation of six spectrally overlapping fluorophores using either short (∼790 nm) or long (∼1090 nm) wavelengths, and that the newly characterized excitation peaks measured past 1000 nm offer improved photostability and enhanced fidelity of linear spectral unmixing at depth compared to shorter wavelengths.
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Affiliation(s)
- Ryan T. Lang
- Translational Biophotonics Cluster, Northeastern University, Boston, MA 02115, USA
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Bryan Q. Spring
- Translational Biophotonics Cluster, Northeastern University, Boston, MA 02115, USA
- Department of Physics, Northeastern University, Boston, MA 02115, USA
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
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5
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James DS, Campagnola PJ. Recent Advancements in Optical Harmonic Generation Microscopy: Applications and Perspectives. BME FRONTIERS 2021; 2021:3973857. [PMID: 37849910 PMCID: PMC10521653 DOI: 10.34133/2021/3973857] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 12/14/2020] [Indexed: 10/19/2023] Open
Abstract
Second harmonic generation (SHG) and third harmonic generation (THG) microscopies have emerged as powerful imaging modalities to examine structural properties of a wide range of biological tissues. Although SHG and THG arise from very different contrast mechanisms, the two are complimentary and can often be collected simultaneously using a modified multiphoton microscope. In this review, we discuss the needed instrumentation for these modalities as well as the underlying theoretical principles of SHG and THG in tissue and describe how these can be leveraged to extract unique structural information. We provide an overview of recent advances showing how SHG microscopy has been used to evaluate collagen alterations in the extracellular matrix and how this has been used to advance our knowledge of cancers, fibroses, and the cornea, as well as in tissue engineering applications. Specific examples using polarization-resolved approaches and machine learning algorithms are highlighted. Similarly, we review how THG has enabled developmental biology and skin cancer studies due to its sensitivity to changes in refractive index, which are ubiquitous in all cell and tissue assemblies. Lastly, we offer perspectives and outlooks on future directions of SHG and THG microscopies and present unresolved questions, especially in terms of overall miniaturization and the development of microendoscopy instrumentation.
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Affiliation(s)
- Darian S. James
- Department of Biomedical Engineering, University of Wisconsin-Madison, 1550 Engineering Dr, Madison, WI 53706, USA
| | - Paul J. Campagnola
- Department of Biomedical Engineering, University of Wisconsin-Madison, 1550 Engineering Dr, Madison, WI 53706, USA
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6
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Majumder M, Goswami T, Misra A. Multifunctional Magnetic Materials of Organic Origin for Biomedical Applications: A Theoretical Study. ChemistrySelect 2018. [DOI: 10.1002/slct.201702530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Manoj Majumder
- Department of ChemistryUniversity of North Bengal Darjeeling 734013, West Bengal India
| | - Tamal Goswami
- Department of ChemistryUniversity of North Bengal Darjeeling 734013, West Bengal India
| | - Anirban Misra
- Department of ChemistryUniversity of North Bengal Darjeeling 734013, West Bengal India
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7
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Dunn KW, Sutton TA, Sandoval RM. Live-Animal Imaging of Renal Function by Multiphoton Microscopy. ACTA ACUST UNITED AC 2018; 83:12.9.1-12.9.25. [PMID: 29345326 DOI: 10.1002/cpcy.32] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Intravital microscopy, microscopy of living animals, is a powerful research technique that combines the resolution and sensitivity found in microscopic studies of cultured cells with the relevance and systemic influences of cells in the context of the intact animal. The power of intravital microscopy has recently been extended with the development of multiphoton fluorescence microscopy systems capable of collecting optical sections from deep within the kidney at subcellular resolution, supporting high-resolution characterizations of the structure and function of glomeruli, tubules, and vasculature in the living kidney. Fluorescent probes are administered to an anesthetized, surgically prepared animal, followed by image acquisition for up to 3 hr. Images are transferred via a high-speed network to specialized computer systems for digital image analysis. This general approach can be used with different combinations of fluorescent probes to evaluate processes such as glomerular permeability, proximal tubule endocytosis, microvascular flow, vascular permeability, mitochondrial function, and cellular apoptosis/necrosis. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Kenneth W Dunn
- Indiana University School of Medicine, Indianapolis, Indiana
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8
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Quantification of the Metabolic State in Cell-Model of Parkinson's Disease by Fluorescence Lifetime Imaging Microscopy. Sci Rep 2016; 6:19145. [PMID: 26758390 PMCID: PMC4725947 DOI: 10.1038/srep19145] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 12/07/2015] [Indexed: 12/17/2022] Open
Abstract
Intracellular endogenous fluorescent co-enzymes, reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), play a pivotal role in cellular metabolism; quantitative assessment of their presence in living cells can be exploited to monitor cellular energetics in Parkinson's disease (PD), a neurodegenerative disorder. Here, we applied two-photon fluorescence lifetime imaging microscopy (2P-FLIM) to noninvasively measure the fluorescence lifetime components of NADH and FAD, and their relative contributions in MPP(+) (1-methyl-4-phenylpyridinium) treated neuronal cells, derived from PC12 cells treated with nerve growth factor (NGF), to mimic PD conditions. A systematic FLIM data analysis showed a statistically significant (p < 0.001) decrease in the fluorescence lifetime of both free and protein-bound NADH, as well as free and protein-bound FAD in MPP(+) treated cells. On the relative contributions of the free and protein-bound NADH and FAD to the life time, however, both the free NADH contribution and the corresponding protein-bound FAD contribution increase significantly (p < 0.001) in MPP(+) treated cells, compared to control cells. These results, which indicate a shift in energy production in the MPP(+) treated cells from oxidative phosphorylation towards anaerobic glycolysis, can potentially be used as cellular metabolic metrics to assess the condition of PD at the cellular level.
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9
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Pais VF, Alcaide MM, López-Rodríguez R, Collado D, Nájera F, Pérez-Inestrosa E, Álvarez E, Lassaletta JM, Fernández R, Ros A, Pischel U. Strongly Emissive and Photostable Four-Coordinate Organoboron N,C Chelates and Their Use in Fluorescence Microscopy. Chemistry 2015; 21:15369-76. [DOI: 10.1002/chem.201501626] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Indexed: 11/09/2022]
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10
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Finas D, Janine SF, Benjamin S, Gereon H, Achim R, Thorsten B, Kerstin LB. SPIO processing in macrophages for MPI: The breast cancer MPI-SNLB-concept. CURRENT DIRECTIONS IN BIOMEDICAL ENGINEERING 2015. [DOI: 10.1515/cdbme-2016-0002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Introduction
Breast cancer (BC) is the most common cancer in women worldwide. We aim to develop a new sentinel lymph node biopsy (SLNB) method with superparamagnetic iron oxide nanoparticles (SPIOs) and magnetic particle imaging (MPI) in BC to avoid tissue damaging while axillary surgery. As we know from i.v. SPIO application in magnetic resonance imaging (MRI), macrophages (MP) are key role player in processing of SPIOs (e.g. in liver) causing a drop of signal intensity. But, knowledge lacks concerning enrichment processes of SPIOs after injection in breast tissue, the adjacent lymphatic tissues and associated cells, especially in BC and metastatic lymph nodes. We already evaluated the distribution of SPIOs in an in vivo healthy and tumor mouse model. Based on these studies we investigate the processing of the SPIOs in MP.
Material and Methods
To evaluate SPIO processing, a mouse MP cell line J774A.1 was incubated either by Resovist in culture medium (RPMI, FBS), or culture medium only as control. MP were than analyzed by transmission electron microscopy (TEM). Additionally, this process was observed in vivo by multiphoton microscopy. Detection of SPIOs was realized by excitation at 1200 nm.
Results
Resovist had no toxic effects on cells.MP showed activity in phagocytosis of Resovist after incubation in TEM as well as in multiphoton microscopy. SPIOs were detectable within intracellular vesicles by TEM and 3-photon process. The first cell associated SPIO signal was detected after 1,5 min of incubation by in vivo imaging.
Conclusion
To our knowledge this is the first time a 3-photon device was used to image SPIOs in a bio-medical context. System wide scanning is known (MRI, MPI), but nowwe are also able to identify the link to subcellular processing and localization of SPIOs. Further processing of SPIOs in MP is under development.
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Affiliation(s)
- Dominique Finas
- Evangelical Hospital Bielefeld, Burgsteig 13, 33617 Bielefeld, Germany, phone +49 521 772 75381, fax +49 521 772 75384
| | | | - Sauer Benjamin
- University of Lübeck, Institute of Biomedical Optics, Germany
| | - Hüttmann Gereon
- University of Lübeck, Institute of Biomedical Optics, Germany
| | - Rody Achim
- University of Lübeck, Department of Obstetrics and Gynecology, Germany
| | - Buzug Thorsten
- University of Lübeck, Institute of Medical Engineering, Germany
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11
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Vigil GD, Adami AJ, Ahmed T, Khan A, Chapman S, Andemariam B, Thrall RS, Howard SS. Label-free and depth resolved optical sectioning of iron-complex deposits in sickle cell disease splenic tissue by multiphoton microscopy. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:066001. [PMID: 26042382 DOI: 10.1117/1.jbo.20.6.066001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 04/21/2015] [Indexed: 06/04/2023]
Abstract
Multiphoton microscopy (MPM) imaging of intrinsic two-photon excited fluorescence (TPEF) is performed on humanized sickle cell disease (SCD) mouse model splenic tissue. Distinct morphological and spectral features associated with SCD are identified and discussed in terms of diagnostic relevance. Specifically, spectrally unique splenic iron-complex deposits are identified by MPM; this finding is supported by TPEF spectroscopy and object size to standard histopathological methods. Further, iron deposits are found at higher concentrations in diseased tissue than in healthy tissue by all imaging methods employed here including MPM, and therefore, may provide a useful biomarker related to the disease state. These newly characterized biomarkers allow for further investigations of SCD in live animals as a means to gain insight into the mechanisms impacting immune dysregulation and organ malfunction, which are currently not well understood.
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Affiliation(s)
- Genevieve D Vigil
- University of Notre Dame, Department of Electrical Engineering, 275 Fitzpatrick Hall, Notre Dame, Indiana 46556, United States
| | - Alexander J Adami
- University of Connecticut Health Center, Department of Immunology, 263 Farmington Avenue, Farmington, Connecticut 06030-3710, United States
| | - Tahsin Ahmed
- University of Notre Dame, Department of Electrical Engineering, 275 Fitzpatrick Hall, Notre Dame, Indiana 46556, United States
| | - Aamir Khan
- University of Notre Dame, Department of Electrical Engineering, 275 Fitzpatrick Hall, Notre Dame, Indiana 46556, United States
| | - Sarah Chapman
- University of Notre Dame, Notre Dame Integrated Imaging Facility Histology Core, 400 D Friemann Life Science Center, Notre Dame, Indiana 46556, United States
| | - Biree Andemariam
- University of Connecticut Health Center, Department of Medicine, 263 Farmington Avenue, Farmington, Connecticut 06030-3710, United States
| | - Roger S Thrall
- University of Connecticut Health Center, Department of Immunology, 263 Farmington Avenue, Farmington, Connecticut 06030-3710, United States
| | - Scott S Howard
- University of Notre Dame, Department of Electrical Engineering, 275 Fitzpatrick Hall, Notre Dame, Indiana 46556, United States
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12
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Mandal AK, Sreejith S, He T, Maji SK, Wang XJ, Ong SL, Joseph J, Sun H, Zhao Y. Three-photon-excited luminescence from unsymmetrical cyanostilbene aggregates: morphology tuning and targeted bioimaging. ACS NANO 2015; 9:4796-4805. [PMID: 25951348 DOI: 10.1021/nn507072r] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report an experimental observation of aggregation-induced enhanced luminescence upon three-photon excitation in aggregates formed from a class of unsymmetrical cyanostilbene derivatives. Changing side chains (-CH3, -C6H13, -C7H15O3, and folic acid) attached to the cyanostilbene core leads to instantaneous formation of aggregates with sizes ranging from micrometer to nanometer scale in aqueous conditions. The crystal structure of a derivative with a methyl side chain reveals the planarization in the unsymmetrical cyanostilbene core, causing luminescence from corresponding aggregates upon three-photon excitation. Furthermore, folic acid attached cyanostilbene forms well-dispersed spherical nanoaggregates that show a high three-photon cross-section of 6.0 × 10(-80) cm(6) s(2) photon(-2) and high luminescence quantum yield in water. In order to demonstrate the targeted bioimaging capability of the nanoaggregates, three cell lines (HEK293 healthy cell line, MCF7 cancerous cell line, and HeLa cancerous cell line) were employed for the investigations on the basis of their different folate receptor expression level. Two kinds of nanoaggregates with and without the folic acid targeting ligand were chosen for three-photon bioimaging studies. The cell viability of three types of cells incubated with high concentration of nanoaggregates still remained above 70% after 24 h. It was observed that the nanoaggregates without the folic acid unit could not undergo the endocytosis by both healthy and cancerous cell lines. No obvious endocytosis of folic acid attached nanoaggregates was observed from the HEK293 and MCF7 cell lines having a low expression of the folate receptor. Interestingly, a significant amount of endocytosis and internalization of folic acid attached nanoaggregates was observed from HeLa cells with a high expression of the folate receptor under three-photon excitation, indicating targeted bioimaging of folic acid attached nanoaggregates to the cancer cell line. This study presents a paradigm of using organic nanoaggregates for targeted three-photon bioimaging.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Yanli Zhao
- ¶School of Materials Science and Engineering, Nanyang Technological University, 639798 Singapore
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13
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Pauszek RF, Kodali G, Stanley RJ. Excited state electronic structures of 5,10-methenyltetrahydrofolate and 5,10-methylenetetrahydrofolate determined by Stark spectroscopy. J Phys Chem A 2014; 118:8320-8. [PMID: 24814224 DOI: 10.1021/jp501143u] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Folates are ubiquitous cofactors that participate in a wide variety of critical biological processes. 5,10-Methenyltetrahydrofolate and its photodegradation product 5,10-methylenetetrahydrofolate are both associated with the light-driven DNA repair protein DNA photolyase and its homologues (e.g., cryptochromes). The excited state electronic properties of these folate molecules have been studied here using Stark spectroscopy and complementary quantum calculations. The tetrahydrofolates have relatively large difference dipole moments (ca. 6-8 Debye) and difference polarizabilities (ca. 100 Å(3)). This extensive excited state charge redistribution appears to be due largely to the pendant p-aminobenzoic acid group, which helps shuttle charge over the entirety of the molecule. Simple calculations based on the experimental difference dipole moments suggest that tetrahydrofolates should have large two photon cross sections sufficient to enable two photon microscopy to selectively detect and follow folate-containing proteins both in vitro and in vivo.
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Affiliation(s)
- Raymond F Pauszek
- Department of Chemistry, Temple University , Philadelphia, Pennsylvania 19122, United States
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14
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Clark TB, Ziółkowski M, Schatz GC, Goodson T. Two-Photon and Time-Resolved Fluorescence Spectroscopy as Probes for Structural Determination in Amyloid-β Peptides and Aggregates. J Phys Chem B 2014; 118:2351-9. [DOI: 10.1021/jp500883s] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Travis B. Clark
- Department
of Chemistry, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Marcin Ziółkowski
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - George C. Schatz
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Theodore Goodson
- Department
of Chemistry, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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15
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Olesiak-Banska J, Matczyszyn K, Zaleśny R, Murugan NA, Kongsted J, Ågren H, Bartkowiak W, Samoc M. Revealing Spectral Features in Two-Photon Absorption Spectrum of Hoechst 33342: A Combined Experimental and Quantum-Chemical Study. J Phys Chem B 2013; 117:12013-9. [DOI: 10.1021/jp407144k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joanna Olesiak-Banska
- Institute of Physical
and Theoretical Chemistry, Wrocław University of Technology, Wyb. Wyspiańskiego
27, PL-50370 Wrocław, Poland
| | - Katarzyna Matczyszyn
- Institute of Physical
and Theoretical Chemistry, Wrocław University of Technology, Wyb. Wyspiańskiego
27, PL-50370 Wrocław, Poland
| | - Robert Zaleśny
- Institute of Physical
and Theoretical Chemistry, Wrocław University of Technology, Wyb. Wyspiańskiego
27, PL-50370 Wrocław, Poland
- Division of Theoretical
Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - N. Arul Murugan
- Division of Theoretical
Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Jacob Kongsted
- Department
of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Hans Ågren
- Division of Theoretical
Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Wojciech Bartkowiak
- Institute of Physical
and Theoretical Chemistry, Wrocław University of Technology, Wyb. Wyspiańskiego
27, PL-50370 Wrocław, Poland
| | - Marek Samoc
- Institute of Physical
and Theoretical Chemistry, Wrocław University of Technology, Wyb. Wyspiańskiego
27, PL-50370 Wrocław, Poland
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16
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Ftouni H, Bolze F, de Rocquigny H, Nicoud JF. Functionalized Two-Photon Absorbing Diketopyrrolopyrrole-Based Fluorophores for Living Cells Fluorescent Microscopy. Bioconjug Chem 2013; 24:942-50. [DOI: 10.1021/bc300623q] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hussein Ftouni
- Laboratoire de Biophotonique et Pharmacologie
(UMR 7213), Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, CS 60024, 67401 Illkirch,
France
| | - Frédéric Bolze
- Laboratoire de Biophotonique et Pharmacologie
(UMR 7213), Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, CS 60024, 67401 Illkirch,
France
| | - Hugues de Rocquigny
- Laboratoire de Biophotonique et Pharmacologie
(UMR 7213), Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, CS 60024, 67401 Illkirch,
France
| | - Jean-François Nicoud
- Laboratoire de Biophotonique et Pharmacologie
(UMR 7213), Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, CS 60024, 67401 Illkirch,
France
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17
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Morales AR, Frazer A, Woodward AW, Ahn-White HY, Fonari A, Tongwa P, Timofeeva T, Belfield KD. Design, synthesis, and structural and spectroscopic studies of push-pull two-photon absorbing chromophores with acceptor groups of varying strength. J Org Chem 2013; 78:1014-25. [PMID: 23305555 DOI: 10.1021/jo302423p] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new series of unsymmetrical diphenylaminofluorene-based chromophores with various strong π-electron acceptors were synthesized and fully characterized. The systematic alteration of the structural design facilitated the investigation of effects such as molecular symmetry and strength of electron-donating and/or -withdrawing termini have on optical nonlinearity. In order to determine the electronic and geometrical properties of the novel compounds, a thorough investigation was carried out by a combination of linear and nonlinear spectroscopic techniques, single-crystal X-ray diffraction, and quantum chemical calculations. Finally, on the basis of two-photon absorption (2PA) cross sections, the general trend for π-electron accepting ability, i.e., ability to accept charge transfer from diphenylamine was: 2-pyran-4-ylidene malononitrile (pyranone) > dicyanovinyl > bis(dicyanomethylidene)indane >1-(thiophen-2-yl)propenone > dicyanoethylenyl >3-(thiophen-2-yl)propenone. An analogue with the 2-pyran-4-ylidene malononitrile acceptor group exhibited a nearly 3-fold enhancement of the 2PA cross section (1650 GM at 840 nm), relative to other members of the series.
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Affiliation(s)
- Alma R Morales
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816-2366, USA
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18
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Norris G, Amor R, Dempster J, Amos WB, McConnell G. Increased signals from short-wavelength-excited fluorescent molecules using sub-Ti:Sapphire wavelengths. J Microsc 2012; 248:200-7. [PMID: 23078118 PMCID: PMC3746106 DOI: 10.1111/j.1365-2818.2012.03663.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Accepted: 08/14/2012] [Indexed: 11/28/2022]
Abstract
We report the use of an all-solid-state ultrashort pulsed source specifically for two-photon microscopy at wavelengths shorter than those of the conventional Ti:Sapphire laser. Our approach involves sum-frequency mixing of the output from an optical parametric oscillator (λ= 1400-1640 nm) synchronously pumped by a Yb-doped fibre laser (λ= 1064 nm), with the residual pump radiation. This generated an fs-pulsed output tunable in the red spectral region (λ= 620-636 nm, ~150 mW, 405 fs, 80 MHz, M(2) ~ 1.3). We demonstrate the performance of our ultrashort pulsed system using fluorescently labelled and autofluorescent tissue, and compare with conventional Ti:Sapphire excitation. We observe a more than 3-fold increase in fluorescence signal intensity using our visible laser source in comparison with the Ti:Sapphire laser for two-photon excitation at equal illumination peak powers of 1.16 kW or less.
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Affiliation(s)
- G Norris
- Centre for Biophotonics, SIPBS, University of Strathclyde, Glasgow, UK
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19
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Collot M, Loukou C, Yakovlev AV, Wilms CD, Li D, Evrard A, Zamaleeva A, Bourdieu L, Léger JF, Ropert N, Eilers J, Oheim M, Feltz A, Mallet JM. Calcium rubies: a family of red-emitting functionalizable indicators suitable for two-photon Ca2+ imaging. J Am Chem Soc 2012; 134:14923-31. [PMID: 22816677 DOI: 10.1021/ja304018d] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We designed Calcium Rubies, a family of functionalizable BAPTA-based red-fluorescent calcium (Ca(2+)) indicators as new tools for biological Ca(2+) imaging. The specificity of this Ca(2+)-indicator family is its side arm, attached on the ethylene glycol bridge that allows coupling the indicator to various groups while leaving open the possibility of aromatic substitutions on the BAPTA core for tuning the Ca(2+)-binding affinity. Using this possibility we now synthesize and characterize three different CaRubies with affinities between 3 and 22 μM. Their long excitation and emission wavelengths (peaks at 586/604 nm) allow their use in otherwise challenging multicolor experiments, e.g., when combining Ca(2+) uncaging or optogenetic stimulation with Ca(2+) imaging in cells expressing fluorescent proteins. We illustrate this capacity by the detection of Ca(2+) transients evoked by blue light in cultured astrocytes expressing CatCh, a light-sensitive Ca(2+)-translocating channelrhodopsin linked to yellow fluorescent protein. Using time-correlated single-photon counting, we measured fluorescence lifetimes for all CaRubies and demonstrate a 10-fold increase in the average lifetime upon Ca(2+) chelation. Since only the fluorescence quantum yield but not the absorbance of the CaRubies is Ca(2+)-dependent, calibrated two-photon fluorescence excitation measurements of absolute Ca(2+) concentrations are feasible.
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Affiliation(s)
- Mayeul Collot
- UPMC Université Paris 06, Ecole Normale Supérieure, Paris, F-75005 France
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20
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Shao J, Guan Z, Yan Y, Jiao C, Xu QH, Chi C. Synthesis and characterizations of star-shaped octupolar triazatruxenes-based two-photon absorption chromophores. J Org Chem 2011; 76:780-90. [PMID: 21210649 DOI: 10.1021/jo1017926] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A series of star-shaped octupolar triazatruxenes (TATs, 1-6) with intramolecular "push-pull" structure were synthesized and their photophysical properties have been systematically investigated. These chromophores showed obvious solvatochromic effect, i.e., significant bathochromic shift of the emission spectra and larger Stokes shifts were observed in more polar solvents mainly due to photoinduced intramolecular charge transfer (ICT). The two-photon absorption (2PA) cross-section values were determined by two-photon excited fluorescence (2PEF) measurements in toluene and THF. These chromophores exhibited large two-photon absorption cross-sections ranging from 280 to 1620 GM in the near-infrared (NIR) region. Compound 6 showed the largest 2PA action cross-section (σ(2)Φ) of 564 GM and could be a potential two-photon fluorescent (2PF) probe. In addition, compounds 1-6 all displayed good thermal stability and photostability.
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Affiliation(s)
- Jinjun Shao
- Department of Chemistry, National University of Singapore, Singapore
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21
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Garner LE, Park J, Dyar SM, Chworos A, Sumner JJ, Bazan GC. Modification of the Optoelectronic Properties of Membranes via Insertion of Amphiphilic Phenylenevinylene Oligoelectrolytes. J Am Chem Soc 2010; 132:10042-52. [DOI: 10.1021/ja1016156] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Logan E. Garner
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, U.S. Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, Maryland 20783, and School of Chemical Engineering and Materials Science, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul, Korea
| | - Juhyun Park
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, U.S. Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, Maryland 20783, and School of Chemical Engineering and Materials Science, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul, Korea
| | - Scott M. Dyar
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, U.S. Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, Maryland 20783, and School of Chemical Engineering and Materials Science, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul, Korea
| | - Arkadiusz Chworos
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, U.S. Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, Maryland 20783, and School of Chemical Engineering and Materials Science, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul, Korea
| | - James J. Sumner
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, U.S. Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, Maryland 20783, and School of Chemical Engineering and Materials Science, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul, Korea
| | - Guillermo C. Bazan
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, U.S. Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, Maryland 20783, and School of Chemical Engineering and Materials Science, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul, Korea
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22
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Nag OK, Nayak RR, Lim CS, Kim IH, Kyhm K, Cho BR, Woo HY. Two-Photon Absorption Properties of Cationic 1,4-Bis(styryl)benzene Derivative and Its Inclusion Complexes with Cyclodextrins. J Phys Chem B 2010; 114:9684-90. [DOI: 10.1021/jp102682m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Okhil Kumar Nag
- Departments of Nanofusion Technology and Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang 627-706, Republic of Korea, Department of Physics Education, Pusan National University, Busan 609-735, Republic of Korea, and Department of Chemistry, Korea University, Seoul 136-701, Republic of Korea
| | - Rati Ranjan Nayak
- Departments of Nanofusion Technology and Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang 627-706, Republic of Korea, Department of Physics Education, Pusan National University, Busan 609-735, Republic of Korea, and Department of Chemistry, Korea University, Seoul 136-701, Republic of Korea
| | - Chang Su Lim
- Departments of Nanofusion Technology and Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang 627-706, Republic of Korea, Department of Physics Education, Pusan National University, Busan 609-735, Republic of Korea, and Department of Chemistry, Korea University, Seoul 136-701, Republic of Korea
| | - In Hong Kim
- Departments of Nanofusion Technology and Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang 627-706, Republic of Korea, Department of Physics Education, Pusan National University, Busan 609-735, Republic of Korea, and Department of Chemistry, Korea University, Seoul 136-701, Republic of Korea
| | - Kwangseuk Kyhm
- Departments of Nanofusion Technology and Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang 627-706, Republic of Korea, Department of Physics Education, Pusan National University, Busan 609-735, Republic of Korea, and Department of Chemistry, Korea University, Seoul 136-701, Republic of Korea
| | - Bong Rae Cho
- Departments of Nanofusion Technology and Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang 627-706, Republic of Korea, Department of Physics Education, Pusan National University, Busan 609-735, Republic of Korea, and Department of Chemistry, Korea University, Seoul 136-701, Republic of Korea
| | - Han Young Woo
- Departments of Nanofusion Technology and Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang 627-706, Republic of Korea, Department of Physics Education, Pusan National University, Busan 609-735, Republic of Korea, and Department of Chemistry, Korea University, Seoul 136-701, Republic of Korea
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23
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Yao S, Ahn HY, Wang X, Fu J, Van Stryland EW, Hagan DJ, Belfield KD. Donor-acceptor-donor fluorene derivatives for two-photon fluorescence lysosomal imaging. J Org Chem 2010; 75:3965-74. [PMID: 20481577 PMCID: PMC2888463 DOI: 10.1021/jo100554j] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As part of a strategy to achieve large two-photon absorptivity in fluorene-based probes, a series of donor-acceptor-donor (D-A-D) type derivatives were synthesized and their two-photon absorption (2PA) properties investigated. The synthesis of D-A-D fluorophores was achieved by efficient preparation of key intermediates for the introduction of central electron acceptor groups. To accomplish the synthesis of two of the new derivatives, a high-yield method for a one-step direct dibromomethylation of phenyl sulfide was developed. The linear and nonlinear optical properties, including UV-vis absorption, fluorescence emission, fluorescence anisotropy, and two-photon absorption (2PA), of the new D-A-D compounds were measured and compared to their D-A or D-D counterparts. Fully conjugated acceptor moieties in the center of the D-A-D fluorophore led to the greatest increase in the 2PA cross section, while weakly conjugated central acceptors exhibited only a modest increase in the 2PA cross section relative to D-A diploar analogs. Encapsulation of the new probes in Pluronic F 108NF micelles, and subsequent incubation in HCT 116 cells, resulted in very high lysosomal colocalization (>0.98 colocalization coefficient) relative to commercial Lysotracker Red, making the micelle-encapsulated dyes particularly attractive as fluorescent probes for two-photon fluorescence microscopy lysosomal imaging.
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Affiliation(s)
- Sheng Yao
- Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 USA
| | - Hyo-Yang Ahn
- Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 USA
| | - Xuhua Wang
- Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 USA
| | - Jie Fu
- CREOL: The College of Optics and Photonics, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 USA
| | - Eric W. Van Stryland
- CREOL: The College of Optics and Photonics, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 USA
| | - David J. Hagan
- CREOL: The College of Optics and Photonics, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 USA
| | - Kevin D. Belfield
- Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 USA
- CREOL: The College of Optics and Photonics, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 USA
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24
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Kadjane P, Starck M, Camerel F, Hill D, Hildebrandt N, Ziessel R, Charbonnière LJ. Divergent Approach to a Large Variety of Versatile Luminescent Lanthanide Complexes. Inorg Chem 2009; 48:4601-3. [DOI: 10.1021/ic9001169] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Pascal Kadjane
- Laboratoire de Chimie Organique et Spectroscopies Avancées, UMR 7515 associée au CNRS, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 02, France
| | - Matthieu Starck
- Laboratoire de Chimie Organique et Spectroscopies Avancées, UMR 7515 associée au CNRS, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 02, France
| | - Franck Camerel
- Laboratoire de Chimie Organique et Spectroscopies Avancées, UMR 7515 associée au CNRS, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 02, France
| | - Diana Hill
- Institut für Chemie, Physikalische Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24−25, 14476 Potsdam-Golm, Germany
| | - Niko Hildebrandt
- Fraunhofer Institute for Applied Polymer Research, NanoPolyPhotonics, Wissenschaftspark Golm, Geiselbergstrasse 69, 14476 Postdam-Golm, Germany,
| | - Raymond Ziessel
- Laboratoire de Chimie Organique et Spectroscopies Avancées, UMR 7515 associée au CNRS, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 02, France
| | - Loïc J. Charbonnière
- Laboratoire de Chimie Organique et Spectroscopies Avancées, UMR 7515 associée au CNRS, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 02, France
- Laboratoire d’Ingénierie Moléculaire Analytique, UMR 7178 CNRS, IPHC, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 02, France
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25
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Bazan GC. Novel organic materials through control of multichromophore interactions. J Org Chem 2007; 72:8615-35. [PMID: 17887701 DOI: 10.1021/jo071176n] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The function of organic semiconducting and light-harvesting materials depends on the organization of the individual molecular components. Our group has tackled the problem of through-space delocalization via the design and synthesis of bichromphoric pairs held in close proximity by the [2.2]paracyclophane core. The linear and nonlinear optical properties of these molecules provide a challenge to theory. They are also useful in delineating the problem of intermolecular contacts in molecular conductivity measurements. Another area of research described here concerns conjugated polyelectrolytes. These macromolecules combine the properties of organic semiconductors and conventional polyelectrolytes. We have used these materials in the development of optically amplified biosensors and have also incorporated them into organic optoelectronic devices. Of particular interest to us is to derive useful structure/property relationships via molecular design that address important basic scientific problems and technological challenges.
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Affiliation(s)
- Guillermo C Bazan
- Department of Chemistry, Institute for Polymers and Organic Solids, University of California, Santa Barbara, CA 93106, USA.
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26
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Leppert J, Krajewski J, Kantelhardt SR, Schlaffer S, Petkus N, Reusche E, Hüttmann G, Giese A. Multiphoton excitation of autofluorescence for microscopy of glioma tissue. Neurosurgery 2006; 58:759-67; discussion 759-67. [PMID: 16575340 DOI: 10.1227/01.neu.0000204885.45644.22] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Intraoperative detection of residual tumor tissue in glioma surgery remains an important challenge because the extent of tumor removal is related to the prognosis of the disease. Multiphoton excited fluorescence tomography of living tissues provides high-resolution structural and photochemical imaging at a subcellular level. In this conceptual study, we have used multiphoton microscopy and fluorescence lifetime imaging (4D microscopy) to image cultured glioma cell lines, solid tumor, and invasive tumor cells in an experimental mouse glioma model and human glioma biopsy specimens. MATERIAL AND METHODS A laser imaging system containing a mode-locked 80 MHz titanium:sapphire laser with a tuning range of 710 to 920 nm, a scan unit, and a time correlated single photon counting board was used to generate autofluorescence intensity images and fluorescence lifetime images of cultured cell lines, experimental intracranial gliomas in mouse brain, and biopsies of human gliomas. RESULTS Multiphoton microscopy of native tumor bearing brain provided structural images of the normal brain anatomy at a subcellular resolution. Solid tumor, the tumor-brain interface, and single invasive tumor cells could be visualized. Fluorescence lifetime imaging demonstrated significantly different decay of the fluorescent signal in tumor versus normal brain, allowing a clear definition of the tumor-brain interface based on this parameter. Distinct fluorescence lifetimes of endogenous fluorophores were found in different cellular compartments in cultured glioma cells. The analysis of the relationship between the laser excitation wavelength and the lifetime of excitable fluorophores demonstrated distinct profiles for cells of different histotypes. CONCLUSION Multiphoton excited fluorescence of endogenous fluorophores allows structural imaging of tumor and central nervous system histo-architecture at a subcellular level. The analysis of the decay of the fluorescent signal within specific excitation volumes by fluorescent lifetime imaging discriminates glioma cells and normal brain, and the excitation/lifetime profiles may further allow differentiation of cellular histotypes. This technology provides a noninvasive optical tissue analysis that may potentially be applied to an intraoperative analysis of resection plains in tumor surgery.
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Affiliation(s)
- Jan Leppert
- Department of Neurosurgery, University Hospital Schleswig-Holstein, Campus Lübeck, Lübeck, Germany
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27
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Han M, Bindewald-Wittich A, Holz FG, Giese G, Niemz MH, Snyder S, Sun H, Yu J, Agopov M, La Schiazza O, Bille JF. Two-photon excited autofluorescence imaging of human retinal pigment epithelial cells. JOURNAL OF BIOMEDICAL OPTICS 2006; 11:010501. [PMID: 16526877 DOI: 10.1117/1.2171649] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Degeneration of retinal pigment epithelial (RPE) cells severely impairs the visual function of retina photoreceptors. However, little is known about the events that trigger the death of RPE cells at the subcellular level. Two-photon excited autofluorescence (TPEF) imaging of RPE cells proves to be well suited to investigate both the morphological and the spectral characteristics of the human RPE cells. The dominant fluorophores of autofluorescence derive from lipofuscin (LF) granules that accumulate in the cytoplasm of the RPE cells with increasing age. Spectral TPEF imaging reveals the existence of abnormal LF granules with blue shifted autofluorescence in RPE cells of aging patients and brings new insights into the complicated composition of the LF granules. Based on a proposed two-photon laser scanning ophthalmoscope, TPEF imaging of the living retina may be valuable for diagnostic and pathological studies of age related eye diseases.
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28
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Woo HY, Liu B, Kohler B, Korystov D, Mikhailovsky A, Bazan GC. Solvent Effects on the Two-Photon Absorption of Distyrylbenzene Chromophores. J Am Chem Soc 2005; 127:14721-9. [PMID: 16231926 DOI: 10.1021/ja052906g] [Citation(s) in RCA: 230] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of organic- and water-soluble distyrylbenzene-based two-photon absorption (TPA) fluorophores containing dialkylamino donor groups at the termini was designed, synthesized, and characterized. The central core was systematically substituted to modulate intramolecular charge transfer (ICT). These molecules allow an examination of solvent effects on the TPA cross section (delta) and on the TPA action cross section. In toluene, the delta values follow the order of ICT strength. The effect of solvent on delta is nonmonotonic: maximum delta was measured in an intermediate polarity solvent (THF) and was lowest in water. We failed to find a correlation between the observed solvent effect and previous theoretical predictions. Hydrogen bonding to the donor groups and aggregation of the optical units in water, which are not included in calculational analysis, may be responsible for the discrepancies between experimental results and theory.
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Affiliation(s)
- Han Young Woo
- Mitsubishi Chemical Center for Advanced Materials, Department of Materials, University of California, Santa Barbara, California 93106, USA
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29
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Woo HY, Hong JW, Liu B, Mikhailovsky A, Korystov D, Bazan GC. Water-soluble [2.2]paracyclophane chromophores with large two-photon action cross sections. J Am Chem Soc 2005; 127:820-1. [PMID: 15656604 DOI: 10.1021/ja0440811] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of alpha,omega-donor-substituted distyrylbenzene dimers held together by the [2.2]paracyclophane core were designed, synthesized, and characterized. Different substituents were chosen to modulate the strength of the donor nitrogen groups and to allow the molecules to be either neutral and soluble in nonpolar organic solvents or charged and water-soluble. The specific neutral structures are (in order of decreasing donor strength) 4,7,12,15-tetra[N,N-bis(6' '-chlorohexyl)-4'-aminostyryl]-[2.2]paracyclophane (1N), 4,7,12,15-tetra[(N-(6' '-chlorohexyl)carbazol-3'-yl)vinyl]-[2.2]paracyclophane (2N), and 4,7,12,15-tetra[N,N-bis(4' '-(6' ''-chlorohexyl)phenyl)-4'-aminostyryl]-[2.2]paracyclophane (3N). The charged species are 4,7,12,15-tetra[N,N-bis(6' '-(N,N,N-trimethylammonium)hexyl)-4'-aminostyryl]-[2.2]paracyclophane octaiodide (1C), 4,7,12,15-tetra[(N-(6' '-(N,N,N-trimethylammonium)hexyl)carbazol-3'-yl)vinyl]-[2.2]paracyclophane octaiodide (2C), and 4,7,12,15-tetra[N,N-bis(4' '-(6' ''-(N,N,N-trimethylammonium)hexyl)phenyl)-4'-aminostyryl]-[2.2]paracyclophane octaiodide (3C). Two-photon excitation spectra, measured using the two-photon induced fluorescence technique, show in toluene the following trend for the two-photon cross sections (delta): 3N > 2N > 1N. In water the delta values follow the same order, 3C approximately 2C > 1C, but are smaller (approximately one-third). Significantly, the fluorescence quantum yield (eta) in water decreases much more for 1, relative to 2 and 3. The two-photon action cross sections (deltaeta) of 2C and 3C are 294 GM and 359 GM, respectively. These values are among the highest reported thus far. These results show that, to maximize the deltaeta in this class of chromophores, one needs to fine-tune the magnitude of the charge transfer character of the excited state, to minimize fluorescence quenching in polar media.
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Affiliation(s)
- Han Young Woo
- Mitsubishi Chemical Center for Advanced Materials, Department of Materials, Institute for Polymers and Organic Solids, University of California, Santa Barbara, California 93106, USA
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Neu TR, Kuhlicke U, Lawrence JR. Assessment of fluorochromes for two-photon laser scanning microscopy of biofilms. Appl Environ Microbiol 2002; 68:901-9. [PMID: 11823234 PMCID: PMC126725 DOI: 10.1128/aem.68.2.901-909.2002] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A major limitation for the use of two-proton laser scanning microscopy (2P-LSM) in biofilm and other studies is the lack of a thorough understanding of the excitation-emission responses of potential fluorochromes. In order to use 2P-LSM, the utility of various fluorochromes and probes specific for a range of biofilm constituents must be evaluated. The fluorochromes tested in this study included classical nucleic acid-specific stains, such as acridine orange (AO) and 4",6"-diamidino-2-phenylindole (DAPI), as well as recently developed stains. In addition, stains specific for biofilm extracellular polymeric substances (EPS matrix components) were tested. Two-photon excitation with a Ti/Sapphire laser was carried out at wavelengths from 760 to 900 nm in 10-nm steps. It was found that autofluorescence of phototrophic organisms (cyanobacteria and green algae) resulted in strong signals for the entire excitation range. In addition, the coenzyme F(420)-related autofluorescence of methanogenic bacteria could be used to obtain images of dense aggregates (excitation wavelength, 780 nm). The intensities of the emission signals for the nucleic acid-specific fluorochromes varied. For example, the intensities were similar for excitation wavelengths ranging from 780 to 900 nm for AO but were higher for a narrower range, 780 to 810 nm, for DAPI. In selective excitation, fading, multiple staining, and combined single-photon-two-photon studies, the recently developed nucleic acid-specific fluorochromes proved to be more suitable regardless of whether they are intended for living or fixed samples. Probes specific for proteins and glycoconjugates allowed two-photon imaging of polymeric biofilm constituents. Selective excitation-emission was observed for Calcofluor White M2R (780 to 800 nm) and SyproOrange (880 to 900 nm). In addition, fluor-conjugated concanavalin A lectins were examined and provided acceptable two-photon emission signals at wavelengths ranging from 780 to 800 nm. Finally, CellTracker, a fluorochrome suitable for long-term labeling of microbial eucaryote cells, was found to give strong emission at wavelengths ranging from 770 to 810 nm. If fluorochromes have the same two-photon excitation cross section, they are suitable for multiple staining and multichannel recording. Generally, if an appropriate excitation wavelength and fluorochrome were used, it was possible to obtain more highly resolved images for thick biofilm samples with two-photon laser microscopy than with conventional single-photon laser microscopy. Due to its potential for higher resolution in light-scattering tissue-like material, such as biofilms, and extremely localized excitation, 2P-LSM is a valuable addition to conventional confocal laser scanning microscopy with single-photon excitation. However, further development of the method and basic research are necessary to take full advantage of nonlinear excitation in studies of interfacial microbial ecology.
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Affiliation(s)
- Thomas R Neu
- Department of Inland Water Research Magdeburg, UFZ Centre for Environmental Research Leipzig-Halle, Brueckstrasse 3a, 39114 Magdeburg, Germany.
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Heikal AA, Hess ST, Baird GS, Tsien RY, Webb WW. Molecular spectroscopy and dynamics of intrinsically fluorescent proteins: coral red (dsRed) and yellow (Citrine). Proc Natl Acad Sci U S A 2000; 97:11996-2001. [PMID: 11050231 PMCID: PMC17283 DOI: 10.1073/pnas.97.22.11996] [Citation(s) in RCA: 243] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/11/2000] [Indexed: 11/18/2022] Open
Abstract
Gene expression of intrinsically fluorescent proteins in biological systems offers new noninvasive windows into cellular function, but optimization of these probes relies on understanding their molecular spectroscopy, dynamics, and structure. Here, the photophysics of red fluorescent protein (dsRed) from discosoma (coral), providing desired longer emission/absorption wavelengths, and an improved yellow fluorescent protein mutant (Citrine) (S65G/V68L/Q69 M/S72A/T203Y) for significant comparison, are characterized by using fluorescence correlation spectroscopy and time-correlated single-photon counting. dsRed fluorescence decays as a single exponential with a 3.65 +/- 0.07-ns time constant, indicating a single emitting state/species independent of pH 4.4-9.0, in contrast with Citrine. However, laser excitation drives reversible fluorescence flicker at 10(3)-10(4) Hz between dark and bright states with a constant partition fraction f(1) = 0.42 +/- 0.06 and quantum yield of approximately 3 x 10(-3). Unlike Citrine (pKa approximately 5.7), pH-dependent proton binding is negligible (pH 3. 9-11) in dsRed. Time-resolved anisotropy of dsRed reveals rapid depolarization (211 +/- 6 ps) plus slow rotational motion (53 +/- 8 ns), in contrast with a single rotational time (16 +/- 2 ns) for Citrine. The molecular dimensions, calculated from rotational and translational diffusion, indicate that dsRed is hydrodynamically 3.8 +/- 0.4 times larger than predicted for a monomer, which suggests an oligomer (possibly a tetramer) configuration even at approximately 10(-9) M. The fast depolarization is attributed to intraoligomer energy transfer between mobile nonparallel chromophores with the initial anisotropy implying a 24 +/- 3 degrees depolarization angle. Large two-photon excitation cross sections ( approximately 100 GM at 990 nm for dsRed and approximately 50 GM at 970 nm for Citrine), advantageous for two-photon-fluorescence imaging in cells, are measured.
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Affiliation(s)
- A A Heikal
- School of Applied and Engineering Physics, Cornell University, Clark Hall, Ithaca, NY 14853, USA
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Patterson GH, Knobel SM, Arkhammar P, Thastrup O, Piston DW. Separation of the glucose-stimulated cytoplasmic and mitochondrial NAD(P)H responses in pancreatic islet beta cells. Proc Natl Acad Sci U S A 2000; 97:5203-7. [PMID: 10792038 PMCID: PMC25806 DOI: 10.1073/pnas.090098797] [Citation(s) in RCA: 233] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Two-photon excitation microscopy was used to image and quantify NAD(P)H autofluorescence from intact pancreatic islets under glucose stimulation. At maximal glucose stimulation, the rise in whole-cell NAD(P)H levels was estimated to be approximately 30 microM. However, because glucose-stimulated insulin secretion involves both glycolytic and Kreb's cycle metabolism, islets were cultured on extracellular matrix that promotes cell spreading and allows spatial resolution of the NAD(P)H signals from the cytoplasm and mitochondria. The metabolic responses in these two compartments are shown to be differentially stimulated by various nutrient applications. The glucose-stimulated increase of NAD(P)H fluorescence within the cytoplasmic domain is estimated to be approximately 7 microM. Likewise, the NAD(P)H increase of the mitochondrial domain is approximately 60 microM and is delayed with respect to the change in cytoplasmic NAD(P)H by approximately 20 sec. The large mitochondrial change in glucose-stimulated NAD(P)H thus dominates the total signal but may depend on the smaller but more rapid cytoplasmic increase.
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Affiliation(s)
- G H Patterson
- Department of Molecular Physiology and Biophysics, 702 Light Hall, Vanderbilt University, Nashville, TN 37232, USA
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Haupts U, Maiti S, Schwille P, Webb WW. Dynamics of fluorescence fluctuations in green fluorescent protein observed by fluorescence correlation spectroscopy. Proc Natl Acad Sci U S A 1998; 95:13573-8. [PMID: 9811841 PMCID: PMC24860 DOI: 10.1073/pnas.95.23.13573] [Citation(s) in RCA: 416] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have investigated the pH dependence of the dynamics of conformational fluctuations of green fluorescent protein mutants EGFP (F64L/S65T) and GFP-S65T in small ensembles of molecules in solution by using fluorescence correlation spectroscopy (FCS). FCS utilizes time-resolved measurements of fluctuations in the molecular fluorescence emission for determination of the intrinsic dynamics and thermodynamics of all processes that affect the fluorescence. Fluorescence excitation of a bulk solution of EGFP decreases to zero at low pH (pKa = 5.8) paralleled by a decrease of the absorption at 488 nm and an increase at 400 nm. Protonation of the hydroxyl group of Tyr-66, which is part of the chromophore, induces these changes. When FCS is used the fluctuations in the protonation state of the chromophore are time resolved. The autocorrelation function of fluorescence emission shows contributions from two chemical relaxation processes as well as diffusional concentration fluctuations. The time constant of the fast, pH-dependent chemical process decreases with pH from 300 microseconds at pH 7 to 45 microseconds at pH 5, while the time-average fraction of molecules in a nonfluorescent state increases to 80% in the same range. A second, pH-independent, process with a time constant of 340 microseconds and an associated fraction of 13% nonfluorescent molecules is observed between pH 8 and 11, possibly representing an internal proton transfer process and associated conformational rearrangements. The FCS data provide direct measures of the dynamics and the equilibrium properties of the protonation processes. Thus FCS is a convenient, intrinsically calibrated method for pH measurements in subfemtoliter volumes with nanomolar concentrations of EGFP.
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Affiliation(s)
- U Haupts
- Max-Planck-Institut für Biochemie, 82152 Martinsried, Germany
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Müller M, Squier J, Wolleschensky R, Simon U, Brakenhoff GJ. Dispersion pre-compensation of 15 femtosecond optical pulses for high-numerical-aperture objectives. J Microsc 1998; 191:141-150. [PMID: 9767477 DOI: 10.1046/j.1365-2818.1998.00357.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The excitation efficiency in two-photon absorption (TPA) microscopy depends strongly - owing to the square dependence of the TPA fluorescence on the excitation intensity - on the temporal width of the excitation pulse. Because of their inherently large frequency bandwidth, ultrashort optical pulses tend to broaden substantially because of dispersion from propagation through the dispersive elements in the microscope. In this paper, the dispersion characteristics of a wide range of microscope objectives are investigated. It is shown that the induced dispersion can be pre-compensated in all cases for pulses as short as 15 fs. Because of the excellent agreement between the results from theoretical modelling and the experimental data, predictions of the possibility of dispersion control for microscope objectives in general, as well as for even shorter pulses, can be inferred. Since for TPA imaging the background due to single photon absorption processes and scattering is independent of the pulse width, proper dispersion pre-compensation - which minimizes the pulse duration at the focal point and hence maximizes the excitation efficiency - provides optimal image contrast in TPA microscopy.
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Affiliation(s)
- M Müller
- BioCentrum Amsterdam, University of Amsterdam, Institute of Molecular Cell Biology, Kruislaan 316, 1098 SM Amsterdam, The Netherlands
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Brand L, Eggeling C, Zander C, Drexhage KH, Seidel CAM. Single-Molecule Identification of Coumarin-120 by Time-Resolved Fluorescence Detection: Comparison of One- and Two-Photon Excitation in Solution. J Phys Chem A 1997. [DOI: 10.1021/jp963729w] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- L. Brand
- Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, 37077 Göttingen, Germany, and Institut für Physikalische Chemie, Universität-Gesamthochschule Siegen, Adolf-Reichwein-Strasse 2, 57068 Siegen, Germany
| | - C. Eggeling
- Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, 37077 Göttingen, Germany, and Institut für Physikalische Chemie, Universität-Gesamthochschule Siegen, Adolf-Reichwein-Strasse 2, 57068 Siegen, Germany
| | - C. Zander
- Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, 37077 Göttingen, Germany, and Institut für Physikalische Chemie, Universität-Gesamthochschule Siegen, Adolf-Reichwein-Strasse 2, 57068 Siegen, Germany
| | - K. H. Drexhage
- Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, 37077 Göttingen, Germany, and Institut für Physikalische Chemie, Universität-Gesamthochschule Siegen, Adolf-Reichwein-Strasse 2, 57068 Siegen, Germany
| | - C. A. M. Seidel
- Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, 37077 Göttingen, Germany, and Institut für Physikalische Chemie, Universität-Gesamthochschule Siegen, Adolf-Reichwein-Strasse 2, 57068 Siegen, Germany
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