The Experts below are selected from a list of 103071 Experts worldwide ranked by ideXlab platform
Qinglai Yang - One of the best experts on this subject based on the ideXlab platform.
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rational design of a super contrast nir ii fluorophore affords high performance nir ii molecular imaging guided microsurgery
Chemical Science, 2019Co-Authors: Rui Tian, Swati Chandra, Qinglai Yang, Dale O. Kiesewetter, Yongye Liang, Xiaoyuan Shawn ChenAbstract:In vivo molecular imaging in the “transparent” near-infrared II (NIR-II) window has demonstrated impressive benefits in reaching millimeter penetration depths with high specificity and imaging quality. Previous NIR-II molecular imaging generally relied on high hepatic uptake Fluorophores with an unclear mechanism and antibody-derived conjugates, suffering from inevitable nonspecific retention in the main organs/skin with a relatively low signal-to-background ratio. It is still challenging to synthesize a NIR-II fluorophore with both high quantum yield and minimal liver-retention feature. Herein, we identified the structural design and excretion mechanism of novel NIR-II Fluorophores for NIR-II molecular imaging with an extremely clean background. With the optimized renally excreted fluorophore–peptide conjugates, superior NIR-II targeting imaging was accompanied by the improved signal-to-background ratio during tumor detection with reducing off-target tissue exposure. An unprecedented NIR-II imaging-guided microsurgery was achieved using such an imaging platform, which provides us with a great preclinical example to accelerate the potential clinical translation of NIR-II imaging.
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developing a bright nir ii fluorophore with fast renal excretion and its application in molecular imaging of immune checkpoint pd l1
Advanced Functional Materials, 2018Co-Authors: Feifei Wang, Qinglai Yang, Zhubin Hu, Mingxi Zhang, Weizhi Wang, Yeteng Zhong, Ye Tian, Yongye LiangAbstract:Fluorescence imaging in the second near-infrared (NIR-II) window holds impressive advantages of enhanced penetration depth and improved signal-to-noise ratio. Bright NIR-II Fluorophores with renal excretion ability and low tissue accumulation are favorable for in vivo molecular imaging applications as they can render the target-mediated molecular imaging process easily distinguishable. Here, a probe (anti-PD-L1-BGP6) comprising a fluorophore (IR-BGP6) covalently bonded to the programmed cell death ligand-1 monoclonal antibody (PD-L1 mAb) for molecular imaging of immune checkpoint PD-L1 (a targeting site upregulated in various tumors for cancer imaging) in the NIR-II window is reported. Through molecular optimization, the bright NIR-II fluorophore IR-BGP6 with fast renal excretion (≈91% excretion in general through urine within the first 10 h postinjection) is developed. The conjugate anti-PD-L1-BGP6 succeeds in profiling PD-L1 expression and realizes efficient noninvasive molecular imaging in vivo, achieving a tumor to normal tissue (T/NT) signal ratio as high as ≈9.5. Compared with the NIR-II fluorophore with high nonspecific tissue accumulation, IR-BGP6 derived PD-L1 imaging significantly enhances the molecular imaging performance, serving as a strong tool for potentially studying underlying mechanism of immunotherapy. The work provides rationales to design renal-excreted NIR-II Fluorophores and illustrate their advantages for in vivo molecular imaging.
Joseph R Lakowicz - One of the best experts on this subject based on the ideXlab platform.
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Metal nanoparticle fluorophore: a powerful fluorescence probe in single cell imaging
Single Molecule Spectroscopy and Imaging III, 2010Co-Authors: Jian Zhang, Richard Y. Zhao, Joseph R LakowiczAbstract:Metal nanoparticle Fluorophores have been developed using metal-enhanced fluorescence (MEF) principle. Compared with the conventional organic Fluorophores, the metal Fluorophores display the increasing brightness and shortening lifetime as well as the lengthening photostability and reducing photoblinking. Conjugated the metal Fluorophores on the surfaces of cell lines, the cell images were recorded on a scanning confocal microscopy in the either emission intensity or lifetime. The emission spots by the conjugated metal Fluorophores were isolated distinctly from the cell images because of their brighter signals and shorter lifetimes. Collected in the three-dimension, the total number of emission signals could be counted quantitatively and the distribution could be described on the cell surfaces. It was noticed that the emission intensity over the cell image was increased with an increase of the number of metal fluorophore on the cell surface and simultaneously the lifetime was altered. A quantitative regression curve was achieved between the amount of metal fluorophore on the cell surface and the emission intensity or lifetime over the entire cell image. Based on this regression curve, the target molecules on the cell surfaces could be quantified readily through the cell intensity and/or lifetime at the single cell level instead of the direct count to the emission spots. As novel molecule imaging agents, these metal Fluorophores are being applied in the quantification and distribution of target molecule on the cell surface for the clinical diagnostic research.
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Computational study of the interaction of Fluorophores with various metallic nanoparticle systems
Plasmonics in Biology and Medicine VI, 2009Co-Authors: Mustafa H. Chowdhury, Stephen K. Gray, James Pond, Joseph R LakowiczAbstract:Finite-difference time-domain calculations are used to study how fluorescence is modified when Fluorophores are located in proximity to various metal nanoparticle systems. The fluorophore is modeled as a radiating point dipole with orientation defined by its polarization. The angle-resolved far-field distributions of the emission in a single plane are computed. The emission patterns show interesting intensity variations and angular profiles depending on the dipole orientation, size of the metal particles and the metal-dipole spacing. We also compute changes in the total radiated power through a closed volume containing the fluorophore and metal nanoparticles relative to an isolated fluorophore. This change in total radiated power is proportional to changes in the relative radiative decay rates of the fluorophore-metal system. Our results suggest a high dependence of the radiated power on the fluorophore orientation, particle size, metalfluorophore distance and particularly the presence of metal nanoparticle dimers. We examined the effect of a fluorophore on the near-fields around silver nanoparticles. The fields can be enhanced compared to the isolated fluorophore and exhibit interesting spatial variations around the nanoparticle that can be useful for applications involving molecular spectroscopy.
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metal enhanced fluorescence an emerging tool in biotechnology
Current Opinion in Biotechnology, 2005Co-Authors: Kadir Aslan, Ignacy Gryczynski, Joseph R Lakowicz, Joanna Malicka, Evgenia G Matveeva, Chris D GeddesAbstract:Over the past 15 years, fluorescence has become the dominant detection/sensing technology in medical diagnostics and biotechnology. Although fluorescence is a highly sensitive technique, where single molecules can readily be detected, there is still a drive for reduced detection limits. The detection of a fluorophore is usually limited by its quantum yield, autofluorescence of the samples and/or the photostability of the Fluorophores; however, there has been a recent explosion in the use of metallic nanostructures to favorably modify the spectral properties of Fluorophores and to alleviate some of these fluorophore photophysical constraints. The use of fluorophore–metal interactions has been termed radiative decay engineering, metal-enhanced fluorescence or surface-enhanced fluorescence.
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radiative decay engineering 4 experimental studies of surface plasmon coupled directional emission
Analytical Biochemistry, 2004Co-Authors: Ignacy Gryczynski, Zygmunt Gryczynski, Joanna Malicka, Joseph R LakowiczAbstract:Fluorescence is typically isotropic in space and collected with low efficiency. In this paper we describe surface plasmon-coupled emission (SPCE), which displays unique optical properties and can be collected with an efficiency near 50%. SPCE occurs for Fluorophores within about 200 nm of a thin metallic film, in our case a 50-nm-thick silver film on a glass substrate. We show that fluorophore proximity to this film converts the normally isotropic emission into highly directional emission through the glass substrate at a well-defined angle from the normal axis. Depending on the thickness of the polyvinyl alcohol (PVA) film on the silver, the coupling efficiency of sulforhodamine 101 in PVA ranged from 30 to 49%. Directional SPCE was observed whether the fluorophore was excited directly or by the evanescent field due to the surface plasmon resonance. The emission is always polarized perpendicular to the plane of incidence, irrespective of the polarization of the incident light. The lifetimes are not substantially changed, indicating a mechanism somewhat different from that observed previously for the effects of silver particles on Fluorophores. Remarkably, the directional emission shows intrinsic spectral resolution because the coupling angles depend on wavelength. The distances over which SPCE occurs, 10 to 200 nm, are useful because a large number of Fluorophores can be localized within this volume. The emission of more distant Fluorophores does not couple into the glass, allowing background suppression from biological samples. SPCE can be expected to become rapidly useful in a variety of analytical and medical sensing applications.
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Anisotropy-Based Sensing with Reference Fluorophores
Analytical Biochemistry, 1999Co-Authors: Joseph R Lakowicz, Ignacy Gryczynski, Zygmunt Gryczynski, Jonathan D. DattelbaumAbstract:Abstract We describe a new approach to fluorescence sensing based on measurements of steady-state anisotropies in the presence of reference Fluorophores with known anisotropies. The basic concept is that the anisotropy of a mixture reflects a weighted average of the anisotropies of the emitting species. By use of reference Fluorophores the starting anisotropy can be near zero, or near 0.9 for oriented films which contain the reference fluorophore. Changing intensities of the analyte result in changes in anisotropy. A wide dynamic range of anisotropies is available because of the freedom to select high or low starting values. Anisotropy-based sensing was demonstrated for pH using 6-carboxyfluorescein and for protein affinity or immunoassay using an oriented film with high anisotropy and a protein labeled with a metal–ligand complex. The latter measurements were performed with a simple light-emitting diode excitation source without an excitation polarizer. The sensitive range of the assay can be adjusted by changing the intensity of the reference fluorophore. Anisotropy-based sensing can have numerous applications in clinical and analytical chemistry.
Markus Sauer - One of the best experts on this subject based on the ideXlab platform.
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Multi-target spectrally resolved fluorescence lifetime imaging microscopy
Nature Methods, 2016Co-Authors: Thomas Niehörster, Anna Löschberger, Ingo Gregor, Benedikt Krämer, Hans-jürgen Rahn, Matthias Patting, Felix Koberling, Jörg Enderlein, Markus SauerAbstract:Spectrally resolved FLIM with three excitation wavelengths and detection on 32 channels combined with advanced pattern matching allows for simultaneous detection and discrimination of Fluorophores with nearly identical emission spectra, enabling highly multiplexed imaging. We introduce a pattern-matching technique for efficient identification of fluorophore ratios in complex multidimensional fluorescence signals using reference fluorescence decay and spectral signature patterns of individual fluorescent probes. Alternating pulsed laser excitation at three different wavelengths and time-resolved detection on 32 spectrally separated detection channels ensures efficient excitation of Fluorophores and a maximum gain of fluorescence information. Using spectrally resolved fluorescence lifetime imaging microscopy (sFLIM), we were able to visualize up to nine different target molecules simultaneously in mouse C2C12 cells. By exploiting the sensitivity of fluorescence emission spectra and the lifetime of organic Fluorophores on environmental factors, we carried out fluorescence imaging of three different target molecules in human U2OS cells with the same fluorophore. Our results demonstrate that sFLIM can be used for super-resolution multi-target imaging by stimulated emission depletion (STED).
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measuring localization performance of super resolution algorithms on very active samples
Optics Express, 2011Co-Authors: Steve Wolter, Mike Heilemann, Ulrike Endesfelder, Sebastian Van De Linde, Markus SauerAbstract:Super-resolution fluorescence imaging based on single-molecule localization relies critically on the availability of efficient processing algorithms to distinguish, identify, and localize emissions of single Fluorophores. In multiple current applications, such as three-dimensional, time-resolved or cluster imaging, high densities of fluorophore emissions are common. Here, we provide an analytic tool to test the performance and quality of localization microscopy algorithms and demonstrate that common algorithms encounter difficulties for samples with high fluorophore density. We demonstrate that, for typical single-molecule localization microscopy methods such as dSTORM and the commonly used rapidSTORM scheme, computational precision limits the acceptable density of concurrently active Fluorophores to 0.6 per square micrometer and that the number of successfully localized Fluorophores per frame is limited to 0.2 per square micrometer.
Yongye Liang - One of the best experts on this subject based on the ideXlab platform.
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rational design of a super contrast nir ii fluorophore affords high performance nir ii molecular imaging guided microsurgery
Chemical Science, 2019Co-Authors: Rui Tian, Swati Chandra, Qinglai Yang, Dale O. Kiesewetter, Yongye Liang, Xiaoyuan Shawn ChenAbstract:In vivo molecular imaging in the “transparent” near-infrared II (NIR-II) window has demonstrated impressive benefits in reaching millimeter penetration depths with high specificity and imaging quality. Previous NIR-II molecular imaging generally relied on high hepatic uptake Fluorophores with an unclear mechanism and antibody-derived conjugates, suffering from inevitable nonspecific retention in the main organs/skin with a relatively low signal-to-background ratio. It is still challenging to synthesize a NIR-II fluorophore with both high quantum yield and minimal liver-retention feature. Herein, we identified the structural design and excretion mechanism of novel NIR-II Fluorophores for NIR-II molecular imaging with an extremely clean background. With the optimized renally excreted fluorophore–peptide conjugates, superior NIR-II targeting imaging was accompanied by the improved signal-to-background ratio during tumor detection with reducing off-target tissue exposure. An unprecedented NIR-II imaging-guided microsurgery was achieved using such an imaging platform, which provides us with a great preclinical example to accelerate the potential clinical translation of NIR-II imaging.
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developing a bright nir ii fluorophore with fast renal excretion and its application in molecular imaging of immune checkpoint pd l1
Advanced Functional Materials, 2018Co-Authors: Feifei Wang, Qinglai Yang, Zhubin Hu, Mingxi Zhang, Weizhi Wang, Yeteng Zhong, Ye Tian, Yongye LiangAbstract:Fluorescence imaging in the second near-infrared (NIR-II) window holds impressive advantages of enhanced penetration depth and improved signal-to-noise ratio. Bright NIR-II Fluorophores with renal excretion ability and low tissue accumulation are favorable for in vivo molecular imaging applications as they can render the target-mediated molecular imaging process easily distinguishable. Here, a probe (anti-PD-L1-BGP6) comprising a fluorophore (IR-BGP6) covalently bonded to the programmed cell death ligand-1 monoclonal antibody (PD-L1 mAb) for molecular imaging of immune checkpoint PD-L1 (a targeting site upregulated in various tumors for cancer imaging) in the NIR-II window is reported. Through molecular optimization, the bright NIR-II fluorophore IR-BGP6 with fast renal excretion (≈91% excretion in general through urine within the first 10 h postinjection) is developed. The conjugate anti-PD-L1-BGP6 succeeds in profiling PD-L1 expression and realizes efficient noninvasive molecular imaging in vivo, achieving a tumor to normal tissue (T/NT) signal ratio as high as ≈9.5. Compared with the NIR-II fluorophore with high nonspecific tissue accumulation, IR-BGP6 derived PD-L1 imaging significantly enhances the molecular imaging performance, serving as a strong tool for potentially studying underlying mechanism of immunotherapy. The work provides rationales to design renal-excreted NIR-II Fluorophores and illustrate their advantages for in vivo molecular imaging.
Qinsi Zheng - One of the best experts on this subject based on the ideXlab platform.
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Bright and Photostable Fluorophores for Advanced Fluorescence Microscopy
Biophysical Journal, 2017Co-Authors: Qinsi Zheng, Anand K. Muthusamy, Jonathan B. Grimm, Robert H Singer, Luke D. LavisAbstract:Advanced fluorescence microscopy, including single-molecule and super-resolution imaging, demands bright and photostable Fluorophores. We have recently reported a general approach to improve Fluorophores brightness in living cells by substituting the N,N-dimethylamino groups found in classic dyes with four-membered azetidine rings (Nature Methods 12, 244250 (2015)). In an unpublished work we have synthesized new derivatives containing substituents on the azetidine ring. Using this approach we were able to fine tune the wavelength and fluorogenecity of the fluorophore without affecting brightness. Here, we report that several of these novel substituted-azetidine Fluorophores, as well as the substituted-xanthene ones, exhibit substantial improvements in photostability in living cells. These Fluorophores enable robust multi-color, wash-free imaging with a large photon budget. We are investigating their phototoxicity and mechanism in order to maximize the photostability, to generalize this approach to different Fluorophores, and to apply these Fluorophores to diverse biological settings, including living cells, tissues, and animals. We freely share our Fluorophores with the academic community. This work is supported by HHMI and NIH (U01 EB 021236).
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electronic tuning of self healing Fluorophores for live cell and single molecule imaging
Chemical Science, 2017Co-Authors: Qinsi Zheng, Roger B. Altman, Steffen Jockusch, Zhou Zhou, Hong Zhao, Wesley B Asher, Michael D Holsey, Signe Mathiasen, Peter Geggier, Jonathan A JavitchAbstract:Bright, long-lasting organic Fluorophores enable a broad range of imaging applications. “Self-healing” Fluorophores, in which intra-molecularly linked protective agents quench photo-induced reactive species, exhibit both enhanced photostability and biological compatibility. However, the self-healing strategy has yet to achieve its predicted potential, particularly in the presence of ambient oxygen where live-cell imaging studies must often be performed. To identify key bottlenecks in this technology that can be used to guide further engineering developments, we synthesized a series of Cy5 derivatives linked to the protective agent cyclooctatetraene (COT) and examined the photophysical mechanisms curtailing their performance. The data obtained reveal that the photostability of self-healing Fluorophores is limited by reactivity of the COT protective agent. The addition of electron withdrawing substituents to COT reduced its susceptibility to reactions with molecular oxygen and the fluorophore to which it is attached and increased its capacity to participate in triplet energy transfer. Exploiting these insights, we designed and synthesized a suite of modified COT-Fluorophores spanning the visible spectrum that exhibited markedly increased intra-molecular photostabilization. Under ambient oxygen conditions, the photostability of Cy3 and Cy5 fluorophore derivatives increased by 3- and 9-fold in vitro and by 2- and 6-fold in living cells, respectively. We further show that this approach can improve a silicon rhodamine fluorophore. These findings offer a clear strategy for achieving the full potential of the self-healing approach and its application to the gamut of fluorophore species commonly used for biomedical imaging.
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Photostable Fluorophores for Single-Molecule Imaging
Biophysical Journal, 2014Co-Authors: Qinsi Zheng, Roger B. Altman, Steffen Jockusch, Zhou Zhou, Scott C. BlanchardAbstract:Fluorophores exhibit instability (blinking and photobleaching) that limits the spatial and temporal resolution for single-molecule imaging. Although protective agents in solution can mitigate fluorophore instability, their poor solubility in water limits further improvements. Moreover, it is very challenging, if not impossible, to use protective agents in solution for live cell imaging. To overcome these limitations, we linked protective agents to Cy5 Fluorophores. In doing so, we have achieved remarkable enhancements in photostability. We further demonstrated that this strategy provides a general method for improving the photostability of chemically distinct Fluorophores across the visible spectrum.
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on the mechanisms of cyanine fluorophore photostabilization
Journal of Physical Chemistry Letters, 2012Co-Authors: Qinsi Zheng, Roger B. Altman, David J. Warren, Steffen Jockusch, Nicholas J Turro, Zhou Zhou, Scott C. BlanchardAbstract: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 that of 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.