1
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Adablah JE, Wang Y, Donohue M, Roper MG. Profiling Glucose-Stimulated and M3 Receptor-Activated Insulin Secretion Dynamics from Islets of Langerhans Using an Extended-Lifetime Fluorescence Dye. Anal Chem 2020; 92:8464-8471. [PMID: 32429660 PMCID: PMC7304439 DOI: 10.1021/acs.analchem.0c01226] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
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Pulsatile insulin
from pancreatic islets is crucial for glucose
homeostasis, but the mechanism behind coordinated pulsatility is still
under investigation. One hypothesis suggests that cholinergic stimulation
of islets by pancreatic ganglia resets these endocrine units, producing
synchronization. Previously, it was shown that intracellular Ca2+ oscillations within islets can be entrained by pulses of
a cholinergic agonist, carbachol (CCh). Although these proxy measurements
of Ca2+ provided insight into the synchronization mechanism,
measurement of insulin output would be more direct evidence. To this
end, a fluorescence anisotropy competitive immunoassay for online
insulin detection from single and grouped islets in a microfluidic
system was developed using a piezoelectric pressure-driven fluid delivery
system and a squaraine rotaxane fluorophore, SeTau-647, as the fluorescent
label for insulin. Due to SeTau-647 having a longer lifetime and higher
brightness compared to the previously used Cy5 fluorophore, a 45%
increase in the anisotropy range was observed with enhanced signal-to-noise
ratio (S/N) of the measurements. This new system was tested by measuring
glucose-stimulated insulin secretion from single and groups of murine
and human islets. Distinct islet entrainment of groups of murine islets
by pulses of CCh was also observed, providing further evidence for
the hypothesis that pulsatile output from the ganglia can synchronize
islet behavior. We expect that this relatively straightforward, homogeneous
assay can be widely used for examining not only insulin secretion
but other secreted factors from different tissues.
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Affiliation(s)
- Joel E Adablah
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, Florida 32306, United States
| | - Yao Wang
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, Florida 32306, United States
| | - Matthew Donohue
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, Florida 32306, United States
| | - Michael G Roper
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, Florida 32306, United States
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2
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Pal M, Yadav A, Pandey S. Aggregation of Carbocyanine Dyes in Choline Chloride-Based Deep Eutectic Solvents in the Presence of an Aqueous Base. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:9781-9792. [PMID: 28830142 DOI: 10.1021/acs.langmuir.7b01981] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Deep eutectic solvents (DESs) have shown potential as novel media to support molecular aggregation. The self-aggregation behavior of two common and popular carbocyanine dyes, 5,5',6,6'-tetrachloro-1,1'-diethyl-3,3'-di(4-sulfobutyl)-benzimidazole carbocyanine (TDBC) and 5,5'-dichloro-3,3'-di(3-sulfopropyl)-9-methyl-benzothiacarbo cyanine (DMTC), is investigated within DES-based systems under ambient conditions. Although TDBC is known to form J-aggregates in basic aqueous solution, DMTC forms H-aggregates under similar conditions. The DESs used, glyceline and reline, are composed of salt choline chloride and two vastly different H-bond donors, glycerol and urea, respectively, in 1:2 mol ratios. Both DESs in the presence of base are found to support J-aggregates of TDBC. These fluorescent J-aggregates are characterized by small Stokes' shifts and subnanosecond fluorescence lifetimes. Under similar conditions, DMTC forms fluorescent H-aggregates along with J-aggregates within the two DES-based systems. The addition of cationic surfactant cetyltrimethylammonium bromide (CTAB) below its critical micelle concentration (cmc) to a TDBC solution of aqueous base-added glyceline shows the prominent presence of J-aggregates, and increasing the CTAB concentration to above cmc results in the disruption of J-aggregates and the formation of unprecedented H-aggregates. DMTC exclusively forms H-aggregates within a CTAB solution of aqueous base-added glyceline irrespective of the surfactant concentration. Anionic surfactant, sodium dodecylsulfate (SDS), present below its cmc within aqueous base-added DESs supports J-aggregation by TDBC; for similar SDS addition, DMTC forms H-aggregates within the glyceline-based system whereas both H- and J-aggregates exist within the reline-based system. A comparison of the carbocyanine dye behavior in various aqueous base-added DES systems to that in aqueous basic media reveals contrasting aggregation tendencies and/or efficiencies. Surfactants as additives are demonstrated to control and modulate carbocyanine dye self-aggregation within DES-based media. The unique nature of DESs as alternate media toward affecting cyanine dye aggregation is highlighted.
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Affiliation(s)
- Mahi Pal
- Department of Chemistry, Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India
| | - Anita Yadav
- Department of Chemistry, Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India
| | - Siddharth Pandey
- Department of Chemistry, Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India
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3
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Kumar S, Achazi K, Licha K, Manchanda P, Haag R, Sharma SK. Chemo-enzymatic synthesis of dendronized polymers for cyanine dye encapsulation. ADVANCES IN POLYMER TECHNOLOGY 2017. [DOI: 10.1002/adv.21839] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Shiv Kumar
- Department of Chemistry; University of Delhi; Delhi India
| | - Katharina Achazi
- Institut für Chemie und Biochemie; Freie Universität Berlin; Berlin Germany
| | - Kai Licha
- Institut für Chemie und Biochemie; Freie Universität Berlin; Berlin Germany
| | | | - Rainer Haag
- Institut für Chemie und Biochemie; Freie Universität Berlin; Berlin Germany
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4
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Pauli J, Pochstein M, Haase A, Napp J, Luch A, Resch-Genger U. Influence of Label and Charge Density on the Association of the Therapeutic Monoclonal Antibodies Trastuzumab and Cetuximab Conjugated to Anionic Fluorophores. Chembiochem 2016; 18:101-110. [DOI: 10.1002/cbic.201600299] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 10/28/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Jutta Pauli
- Federal Institute for Materials Research and Testing (BAM); Division 1.10 Biophotonics; Richard-Willstaetter-Strasse 11 12489 Berlin Germany
| | - Marieke Pochstein
- Federal Institute for Materials Research and Testing (BAM); Division 1.10 Biophotonics; Richard-Willstaetter-Strasse 11 12489 Berlin Germany
| | - Andrea Haase
- German Federal Institute for Risk Assessment (BfR); Department of Chemical and Product Safety; Max-Dohrn-Strasse 8-10 10589 Berlin Germany
| | - Joanna Napp
- Institute of Interventional and Diagnostic Radiology; University Medical Center Göttingen; Robert-Koch-Strasse 40 37075 Göttingen Germany
- Department of Haematology and Medical Oncology; University Medical Center Göttingen; Robert-Koch-Strasse 40,
- Department of Molecular Biology of Neuronal Signal; Max-Planck-Institute of Experimental Medicine; Hermann-Rein-Strasse 3 37075 Göttingen Germany
| | - Andreas Luch
- German Federal Institute for Risk Assessment (BfR); Department of Chemical and Product Safety; Max-Dohrn-Strasse 8-10 10589 Berlin Germany
| | - Ute Resch-Genger
- Federal Institute for Materials Research and Testing (BAM); Division 1.10 Biophotonics; Richard-Willstaetter-Strasse 11 12489 Berlin Germany
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5
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Franck JM, Ding Y, Stone K, Qin PZ, Han S. Anomalously Rapid Hydration Water Diffusion Dynamics Near DNA Surfaces. J Am Chem Soc 2015; 137:12013-23. [PMID: 26256693 PMCID: PMC4656248 DOI: 10.1021/jacs.5b05813] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The emerging Overhauser effect dynamic nuclear polarization (ODNP) technique measures the translational mobility of water within the vicinity (5-15 Å) of preselected sites. The work presented here expands the capabilities of the ODNP technique and illuminates an important, previously unseen, property of the translational diffusion dynamics of water at the surface of DNA duplexes. We attach nitroxide radicals (i.e., spin labels) to multiple phosphate backbone positions of DNA duplexes, allowing ODNP to measure the hydration dynamics at select positions along the DNA surface. With a novel approach to ODNP analysis, we isolate the contributions of water molecules at these sites that undergo free translational diffusion from water molecules that either loosely bind to or exchange protons with the DNA. The results reveal that a significant population of water in a localized volume adjacent to the DNA surface exhibits fast, bulk-like characteristics and moves unusually rapidly compared to water found in similar probe volumes near protein and membrane surfaces. Control studies show that the observation of these characteristics are upheld even when the DNA duplex is tethered to streptavidin or the mobility of the nitroxides is altered. This implies that, as compared to protein or lipid surfaces, it is an intrinsic feature of the DNA duplex surface that it interacts only weakly with a significant fraction of the surface hydration water network. The displacement of this translationally mobile water is energetically less costly than that of more strongly bound water by up to several kBT and thus can lower the activation barrier for interactions involving the DNA surface.
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Affiliation(s)
- John M. Franck
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA
- National Biomedical Center for Advanced ESR Technology, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY
| | - Yuan Ding
- Department of Chemistry, University of Southern California, Los Angeles, CA
| | - Katherine Stone
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA
- Pacira Pharmaceuticals, Inc, San Diego, CA
| | - Peter Z. Qin
- Department of Chemistry, University of Southern California, Los Angeles, CA
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA
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6
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Stennett EMS, Ma N, van der Vaart A, Levitus M. Photophysical and dynamical properties of doubly linked Cy3-DNA constructs. J Phys Chem B 2013; 118:152-63. [PMID: 24328104 DOI: 10.1021/jp410976p] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photophysical measurements are reported for Cy3-DNA constructs in which both Cy3 nitrogen atoms are attached to the DNA backbone by short linkers. While this linking was thought to rigidify the orientation of the dye and hinder cis-isomerization, the relatively low fluorescence quantum yield and the presence of a short component in the time-resolved fluorescence decay of the dye indicated that cis-isomerization remained possible. Fluorescence correlation spectroscopy and transient absorption experiments showed that photoisomerization occurred with high efficiency. Molecular dynamics simulations of the trans dye system indicated the presence of stacked and unstacked states, and free energy simulations showed that the barriers for stacking/unstacking were low. In addition, simulations showed that the ground cis state was feasible without DNA distortions. Based on these observations, a model is put forward in which the doubly linked dye can photoisomerize in the unstacked state.
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Affiliation(s)
- Elana M S Stennett
- Department of Chemistry and Biochemistry and the Biodesign Institute, Arizona State University , PO Box 875601, Tempe, Arizona 85287, United States
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7
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Gehne S, Sydow K, Dathe M, Kumke MU. Characterization of Cell-Penetrating Lipopeptide Micelles by Spectroscopic Methods. J Phys Chem B 2013; 117:14215-25. [DOI: 10.1021/jp406053g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Sören Gehne
- University of Potsdam, Institute of Chemistry (Physical Chemistry), Karl-Liebknecht-Str.
24-25, 14476 Potsdam-Golm, Germany
| | - Karl Sydow
- Leibniz Institute for Molecular Pharmacology (FMP), Robert-Roessle-Str.
10, 13125 Berlin, Germany
| | - Margitta Dathe
- Leibniz Institute for Molecular Pharmacology (FMP), Robert-Roessle-Str.
10, 13125 Berlin, Germany
| | - Michael U. Kumke
- University of Potsdam, Institute of Chemistry (Physical Chemistry), Karl-Liebknecht-Str.
24-25, 14476 Potsdam-Golm, Germany
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8
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Pauli J, Licha K, Berkemeyer J, Grabolle M, Spieles M, Wegner N, Welker P, Resch-Genger U. New Fluorescent Labels with Tunable Hydrophilicity for the Rational Design of Bright Optical Probes for Molecular Imaging. Bioconjug Chem 2013; 24:1174-85. [PMID: 23758616 DOI: 10.1021/bc4000349] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jutta Pauli
- BAM Federal Institute for Materials Research and Testing, Division 1.10 Biophotonics,
Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany
| | - Kai Licha
- mivenion GmbH, Robert-Koch-Platz 4, D-10115 Berlin, Germany
| | - Janis Berkemeyer
- BAM Federal Institute for Materials Research and Testing, Division 1.10 Biophotonics,
Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany
| | - Markus Grabolle
- BAM Federal Institute for Materials Research and Testing, Division 1.10 Biophotonics,
Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany
| | - Monika Spieles
- BAM Federal Institute for Materials Research and Testing, Division 1.10 Biophotonics,
Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany
| | - Nicole Wegner
- mivenion GmbH, Robert-Koch-Platz 4, D-10115 Berlin, Germany
| | - Pia Welker
- mivenion GmbH, Robert-Koch-Platz 4, D-10115 Berlin, Germany
| | - Ute Resch-Genger
- BAM Federal Institute for Materials Research and Testing, Division 1.10 Biophotonics,
Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany
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9
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Dang YQ, Li Q, Wang K, Wu Y, Lian L, Zou B. Hydrostatic Pressure Effects on the Fluorescence and FRET Behavior of Cy3-Labeled Phycocyanin System. J Phys Chem B 2012; 116:11010-6. [DOI: 10.1021/jp306466j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Yong-Qiang Dang
- State Key
Laboratory of Supramolecular Structure and Materials and ‡State Key Laboratory of Superhard Materials, Jilin University, No. 2699, Qianjin
Street, Changchun, 130012, People's Republic of China
| | - Qian Li
- State Key
Laboratory of Supramolecular Structure and Materials and ‡State Key Laboratory of Superhard Materials, Jilin University, No. 2699, Qianjin
Street, Changchun, 130012, People's Republic of China
| | - Kai Wang
- State Key
Laboratory of Supramolecular Structure and Materials and ‡State Key Laboratory of Superhard Materials, Jilin University, No. 2699, Qianjin
Street, Changchun, 130012, People's Republic of China
| | - Yuqing Wu
- State Key
Laboratory of Supramolecular Structure and Materials and ‡State Key Laboratory of Superhard Materials, Jilin University, No. 2699, Qianjin
Street, Changchun, 130012, People's Republic of China
| | - Lili Lian
- State Key
Laboratory of Supramolecular Structure and Materials and ‡State Key Laboratory of Superhard Materials, Jilin University, No. 2699, Qianjin
Street, Changchun, 130012, People's Republic of China
| | - Bo Zou
- State Key
Laboratory of Supramolecular Structure and Materials and ‡State Key Laboratory of Superhard Materials, Jilin University, No. 2699, Qianjin
Street, Changchun, 130012, People's Republic of China
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10
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Gehne S, Flehr R, Altevogt A, Berg M, Bannwarth W, Kumke MU. Dye dynamics in three-color FRET samples. J Phys Chem B 2012; 116:10798-806. [PMID: 22882140 DOI: 10.1021/jp3064273] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Time-resolved emission data (fluorescence decay and fluorescence depolarization) of two three-color Förster resonance energy transfer (tc-FRET) systems consisting of a carbostyril donor (D), a ruthenium complex (Ru) as relay dye, and a Cy5 derivative (Cy) or, optionally, an anthraquinone quencher (Q) were carefully analyzed using advanced distribution analysis models. Thereby, it is possible to get information on the flexibility and mobility of the chromophores which are bound to double stranded (ds) DNA. Especially the distance distribution based on the analysis of the fluorescence depolarization is an attractive approach to complement data of fluorescence decay time analysis. The distance distributions extracted from the experimental data were in excellent agreement with those determined from accessible volume (AV) simulations. Moreover, the study showed that for tc-FRET systems the combination of dyes emitting on different time scales (e.g., nanoseconds vs microseconds) is highly beneficial in the distribution analysis of time-resolved luminescence data in cases where macromolecules such as DNA are involved. Here, the short lifetimes can yield information on the rotation of the dye molecule itself and the long lifetime can give insight in the overall dynamics of the macromolecule.
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Affiliation(s)
- Sören Gehne
- Institute of Chemistry (Physical Chemistry), University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany
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11
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Beckford G, Owens E, Henary M, Patonay G. The solvatochromic effects of side chain substitution on the binding interaction of novel tricarbocyanine dyes with human serum albumin. Talanta 2012; 92:45-52. [DOI: 10.1016/j.talanta.2012.01.029] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 01/13/2012] [Indexed: 11/26/2022]
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12
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Grabolle M, Brehm R, Pauli J, Dees FM, Hilger I, Resch-Genger U. Determination of the Labeling Density of Fluorophore–Biomolecule Conjugates with Absorption Spectroscopy. Bioconjug Chem 2012; 23:287-92. [DOI: 10.1021/bc2003428] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Markus Grabolle
- BAM Federal Institute for Materials Research and Testing, Division Biophotonic,
Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
| | - Robert Brehm
- BAM Federal Institute for Materials Research and Testing, Division Biophotonic,
Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
| | - Jutta Pauli
- BAM Federal Institute for Materials Research and Testing, Division Biophotonic,
Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
| | - Franziska M Dees
- Institut für Diagnostische
und Interventionelle Radiologie des Klinikums der Friedrich-Schiller-Universität
Jena (IDIR), Forschungszentrum Lobeda,
Erlanger Allee 101, D-07747 Jena, Germany
| | - Ingrid Hilger
- Institut für Diagnostische
und Interventionelle Radiologie des Klinikums der Friedrich-Schiller-Universität
Jena (IDIR), Forschungszentrum Lobeda,
Erlanger Allee 101, D-07747 Jena, Germany
| | - Ute Resch-Genger
- BAM Federal Institute for Materials Research and Testing, Division Biophotonic,
Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
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13
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Spectroscopic Investigations on the H-Type Aggregation of Coumarin 153 Dye Molecules: Role of Au Nanoparticles and γ- Cyclodextrin. J Fluoresc 2011; 22:303-10. [DOI: 10.1007/s10895-011-0961-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 08/30/2011] [Indexed: 11/25/2022]
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14
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Pauli J, Grabolle M, Brehm R, Spieles M, Hamann FM, Wenzel M, Hilger I, Resch-Genger U. Suitable Labels for Molecular Imaging – Influence of Dye Structure and Hydrophilicity on the Spectroscopic Properties of IgG Conjugates. Bioconjug Chem 2011; 22:1298-308. [DOI: 10.1021/bc1004763] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Jutta Pauli
- BAM Bundesanstalt für Materialforschung und -prüfung, OE I.5, Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
| | - Markus Grabolle
- BAM Bundesanstalt für Materialforschung und -prüfung, OE I.5, Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
| | - Robert Brehm
- BAM Bundesanstalt für Materialforschung und -prüfung, OE I.5, Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
| | - Monika Spieles
- BAM Bundesanstalt für Materialforschung und -prüfung, OE I.5, Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
| | - Franziska M. Hamann
- Institut für Diagnostische und Interventionelle Radiologie des Klinikums der Friedrich-Schiller-Universität Jena (IDIR), Forschungszentrum Lobeda, Erlanger Allee 101, D-07747 Jena, Germany
| | | | - Ingrid Hilger
- Institut für Diagnostische und Interventionelle Radiologie des Klinikums der Friedrich-Schiller-Universität Jena (IDIR), Forschungszentrum Lobeda, Erlanger Allee 101, D-07747 Jena, Germany
| | - Ute Resch-Genger
- BAM Bundesanstalt für Materialforschung und -prüfung, OE I.5, Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany
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15
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Flehr R, Kienzler A, Bannwarth W, Kumke MU. Photophysical characterization of a FRET system using tailor-made DNA oligonucleotide sequences. Bioconjug Chem 2010; 21:2347-54. [PMID: 21114283 DOI: 10.1021/bc100389k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have carried out a detailed photophysical study of the FRET D/A pair consisting of a carbostyril donor and a Ru(II)bathophenanthroline complex acceptor in double-stranded synthetic DNA. Altogether 13 different double-stranded 30 base pair DNAs showing small incremental differences in the distances between donor and acceptor were synthesized. Using the fluorescence of the donor as well as of the acceptor, D/A separations were determined and compared to those derived from a well-established model for DNA distance calculations. The model calculations and anisotropy studies revealed that the donor can nearly be seen as a free rotator allowing the application of the established FRET data evaluation.
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Affiliation(s)
- Roman Flehr
- University of Potsdam, Institute of Chemistry (Physical Chemistry), 14476 Potsdam-Golm, Germany
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16
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Photounbinding of calmodulin from a family of CaM binding peptides. PLoS One 2010; 5:e14050. [PMID: 21124984 PMCID: PMC2987815 DOI: 10.1371/journal.pone.0014050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 09/30/2010] [Indexed: 12/29/2022] Open
Abstract
Background Recent studies have shown that fluorescently labeled antibodies can be dissociated from their antigen by illumination with laser light. The mechanism responsible for the photounbinding effect, however, remains elusive. Here, we give important insights into the mechanism of photounbinding and show that the effect is not restricted to antibody/antigen binding. Methodology/Principal Findings We present studies of the photounbinding of labeled calmodulin (CaM) from a set of CaM-binding peptides with different affinities to CaM after one- and two-photon excitation. We found that the photounbinding effect becomes stronger with increasing binding affinity. Our observation that photounbinding can be influenced by using free radical scavengers, that it does not occur with either unlabeled protein or non-fluorescent quencher dyes, and that it becomes evident shortly after or with photobleaching suggest that photounbinding and photobleaching are closely linked. Conclusions/Significance The experimental results exclude surface effects, or heating by laser irradiation as potential causes of photounbinding. Our data suggest that free radicals formed through photobleaching may cause a conformational change of the CaM which lowers their binding affinity with the peptide or its respective binding partner.
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17
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Plażuk D, Zakrzewski J, Salmain M. Biotin as acylating agent in the Friedel-Crafts reaction. Avidin affinity of biotinyl derivatives of ferrocene, ruthenocene and pyrene and fluorescence properties of 1-biotinylpyrene. Org Biomol Chem 2010; 9:408-17. [PMID: 20967359 DOI: 10.1039/c0ob00319k] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
(D)-Biotin was used for Friedel-Crafts acylation of electron-rich aromatic molecules--ferrocene, ruthenocene and pyrene. The reaction carried out in the presence of trifluoroacetic anhydride and trifluoromethanesulfonic acid afforded the corresponding biotinylarenes in moderate yields. These compounds, although lacking an amide bond, exhibited high affinity for avidin, with the ability to displace 2-(4'-hydroxyphenylazo)-benzoic acid (HABA) in its complex with avidin. Their affinity for avidin was determined by a solid-phase competitive enzymatic assay, which gave IC(50) values in the range of 33-58 nM (under the same conditions biotin showed IC(50) = 24 ± 7 nM). 1-Biotinylpyrene (1c) excited at 355 nm displayed fluorescence emission in aqueous solutions with λ(max) = 461 nm. The fluorescence maximum was shifted to 425 nm upon binding of 1c to avidin. Formation of the avidin-1c complex was also evidenced by quenching of the fluorescence from the protein tryptophan residues (342 nm) and appearance of the emission band of the avidin-bound 1c at 430 nm as a result of a Förster resonance energy transfer (FRET) phenomenon.
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Affiliation(s)
- Damian Plażuk
- Department of Organic Chemistry, University of Łódź, 91-403 Łódź, Tamka 12, Poland
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18
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Pauli J, Brehm R, Spieles M, Kaiser WA, Hilger I, Resch-Genger U. Novel fluorophores as building blocks for optical probes for in vivo near infrared fluorescence (NIRF) imaging. J Fluoresc 2010; 20:681-93. [PMID: 20213244 DOI: 10.1007/s10895-010-0603-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Accepted: 01/29/2010] [Indexed: 11/30/2022]
Abstract
Aiming at the identification of new fluorescent reporters for targeted optical probes, we assessed the application-relevant features of a novel asymmetric cyanine, DY-681, in comparison to the only clinically approved dye indocyanine green (ICG), the golden imaging standard Cy5.5, and the asymmetric cyanine DY-676 successfully exploited by us for the design of different contrast agents. This comparison included the analysis of the spectroscopic properties of the free fluorophores and their thermal stability in aqueous solution as well as their cytotoxic potential. In addition, the absorption and emission features of IgG-conjugated DY-681 were examined. The trimethine DY-681 exhibited spectral features closely resembling that of the pentamethine Cy5.5. Its high thermal stability in phosphate buffer saline (PBS) solution in conjunction with its low cytotoxicity, reaching similar values as determined for Cy5.5 and DY-676, renders this dye more attractive as ICG and, due to its improved fluorescence quantum yield in PBS, also superior to DY-676. Although in PBS, Cy5.5 was still more fluorescent, the fluorescence quantum yields (Phi(f)) of DY-681 and Cy5.5 in PBS containing 5 mass-% bovine serum albumin (BSA) were comparable. Labeling experiments with DY-681 and the model antibody IgG revealed promisingly high Phi(f) values of the bioconjugated dye.
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Affiliation(s)
- Jutta Pauli
- BAM Federal Institute for Materials Research and Testing, Division I.5, Richard-Willstaetter-Str. 11, 12489 Berlin, Germany
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Long-Wavelength Probes and Labels Based on Cyanines and Squaraines. SPRINGER SERIES ON FLUORESCENCE 2010. [DOI: 10.1007/978-3-642-04702-2_3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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20
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Singh MK. Time-resolved single molecule fluorescence spectroscopy of Cy5-dCTP: influence of the immobilization strategy. Phys Chem Chem Phys 2009; 11:7225-30. [PMID: 19672533 DOI: 10.1039/b821632k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The carbocyanine derivative Cy5 is one of the most utilized probes for single molecule fluorescence spectroscopy. To investigate time dependent changes in single molecules a number of immobilization techniques are used. In the present study the influence of the immobilization strategy on the fluorescence lifetime of Cy5-dCTP has been investigated using time-resolved single molecule imaging and spectroscopy techniques. The fluorescence lifetime of single dye molecule adsorbed on glass from aqueous solution (1.03 ns) or on a dry surface (1.23 ns) has been found to match very well with that measured in an ensemble aqueous solution (1.07 ns). However, the lifetime increases drastically when embedded in a film (approximately 2 ns). The changes in the rigidity of the medium have been found to be responsible for the unusual increase observed in the single molecule fluorescence lifetime of the dye. These observations were well supported by the results obtained during bulk measurements.
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Affiliation(s)
- Manoj K Singh
- Spectroscopy Division, Bhabha Atomic Research Centre, Mumbai, India.
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