451
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Deniz E, Kandoth N, Fraix A, Cardile V, Graziano ACE, Lo Furno D, Gref R, Raymo FM, Sortino S. Photoinduced Fluorescence Activation and Nitric Oxide Release with Biocompatible Polymer Nanoparticles. Chemistry 2012; 18:15782-7. [DOI: 10.1002/chem.201202845] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Indexed: 11/09/2022]
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452
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Swaminathan S, Petriella M, Deniz E, Cusido J, Baker JD, Bossi ML, Raymo FM. Fluorescence Photoactivation by Intermolecular Proton Transfer. J Phys Chem A 2012; 116:9928-33. [DOI: 10.1021/jp307787w] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Marco Petriella
- INQUIMAE, Facultad de Ciencias
Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | | | | | | | - Mariano L. Bossi
- INQUIMAE, Facultad de Ciencias
Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, 1428 Buenos Aires, Argentina
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453
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Abstract
Photoactivatable fluorophores switch from a nonemissive to an emissive state upon illumination at an activating wavelength and then emit after irradiation at an exciting wavelength. The interplay of such activation and excitation events can be exploited to switch fluorescence on in a defined region of space at a given interval of time. In turn, the spatiotemporal control of fluorescence translates into the opportunity to implement imaging and spectroscopic schemes that are not possible with conventional fluorophores. Specifically, photoactivatable fluorophores permit the monitoring of dynamic processes in real time as well as the reconstruction of images with subdiffraction resolution. These promising applications can have a significant impact on the characterization of the structures and functions of biomolecular systems. As a result, strategies to implement mechanisms for fluorescence photoactivation with synthetic fluorophores are particularly valuable. In fact, a number of versatile operating principles have already been identified to activate the fluorescence of numerous members of the main families of synthetic dyes. These methods are based on either the irreversible cleavage of covalent bonds or the reversible opening and closing of rings. This paper overviews the fundamental mechanisms that govern the behavior of these photoresponsive systems, illustrates structural designs for fluorescence photoactivation, and provides representative examples of photoactivatable fluorophores in actions.
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Affiliation(s)
- Françisco M. Raymo
- Laboratory for Molecular Photonics, Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146-0431, USA
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454
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Raymo FM. Photoactivatable Synthetic Dyes for Fluorescence Imaging at the Nanoscale. J Phys Chem Lett 2012; 3:2379-2385. [PMID: 26292118 DOI: 10.1021/jz301021e] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The transition from conventional to photoactivatable fluorophores can bring the resolution of fluorescence images from the micrometer to the nanometer level. Indeed, fluorescence photoactivation can overcome the limitations that diffraction imposes on the resolution of optical microscopes. Specifically, distinct fluorophores positioned within the same subdiffraction volume can be resolved only if their emissions are activated independently at different intervals of time. Under these conditions, the sequential localization of multiple probes permits the reconstruction of images with a spatial resolution that is otherwise impossible to achieve with conventional fluorophores. The irreversible photolysis of protecting groups or the reversible transformations of photochromic compounds can be employed to control the emission of appropriate fluorescent chromophores and allow the implementation of these ingenious operating principles for superresolution imaging. Such molecular constructs enable the spatiotemporal control that is required to avoid diffraction and can become invaluable analytical tools for the optical visualization of biological specimens and nanostructured materials with unprecedented resolution.
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Affiliation(s)
- Françisco M Raymo
- Laboratory for Molecular Photonics, Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida 33146-0431, United States
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455
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Zheng Q, Jockusch S, Zhou Z, Altman RB, Warren JD, Turro NJ, Blanchard SC. On the Mechanisms of Cyanine Fluorophore Photostabilization. J Phys Chem Lett 2012; 3:2200-2203. [PMID: 22984636 PMCID: PMC3439216 DOI: 10.1021/jz300670p] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Cyanine fluorophores exhibit greatly improved photostability when covalently linked to stabilizers, such as cyclooctatetraene (COT), nitrobenzyl alcohol (NBA) or Trolox. However, the mechanism by which photostabilization is mediated has yet to be determined. Here we present spectroscopic evidence that COT, when covalently linked to Cy5, substantially reduces the lifetime of the Cy5 triplet state, and that the degree of triplet state quenching correlates with enhancements in photostability observed in single-molecule fluorescence measurements. By contrast, NBA and Trolox did not quench the Cy5 triplet state under our conditions suggesting that their mechanism of photostabilization is different from COT and does not target the fluorophore triplet state directly. These findings provide insights into the mechanisms of fluorophore photostabilization that may lead to improved fluorophore designs for biological imaging applications.
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Affiliation(s)
- Qinsi Zheng
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, United States
- Tri-Institutional Training Program in Chemical Biology, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, United States
| | - Steffen Jockusch
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Zhou Zhou
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, United States
| | - Roger B. Altman
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, United States
| | - J. David Warren
- Department of Biochemistry, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, United States
| | - Nicholas J. Turro
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Scott C. Blanchard
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, United States
- Tri-Institutional Training Program in Chemical Biology, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, United States
- Department of Biochemistry, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, United States
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456
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Quantitative fluorescence labeling of aldehyde-tagged proteins for single-molecule imaging. Nat Methods 2012; 9:499-503. [PMID: 22466795 PMCID: PMC3445270 DOI: 10.1038/nmeth.1954] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 03/08/2012] [Indexed: 11/08/2022]
Abstract
A major hurdle for molecular mechanistic studies of many proteins is the lack of a general method for fluorescent labeling with high efficiency, specificity, and speed. By incorporating an aldehyde motif genetically into a protein and improving the labeling kinetics substantially under mild conditions, we achieved fast, site-specific labeling of a protein with ~100% efficiency while maintaining the biological function. We demonstrate that an aldehyde-tagged protein can be specifically labeled in cell extracts without protein purification and then can be used in single-molecule pull-down analysis. We further show the unique power of our method in a series of single-molecule studies on the transient interactions and switching between two quantitatively labeled DNA polymerases on their processivity factor.
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