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Sadoine M, Reger M, Wong KM, Frommer WB. Affinity Series of Genetically Encoded Förster Resonance Energy-Transfer Sensors for Sucrose. ACS Sens 2021; 6:1779-1784. [PMID: 33974799 DOI: 10.1021/acssensors.0c02495] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Genetically encoded fluorescent sugar sensors are valuable tools for the discovery of transporters and for quantitative monitoring of sugar steady-state levels in intact tissues. Genetically encoded Förster resonance energy-transfer sensors for glucose have been designed and optimized extensively, and a full series of affinity mutants is available for in vivo studies. However, to date, only a single improved sucrose sensor FLIPsuc-90μΔ1 with Km for sucrose of ∼90 μM was available. This sucrose sensor was engineered on the basis of an Agrobacterium tumefaciens sugar-binding protein. Here, we took a two-step approach to first improve the dynamic range of the FLIPsuc sensor and then expand the detection range from micro- to millimolar sucrose concentrations by mutating a key residue in the binding site. The resulting series of sucrose sensors may enable investigation of sucrose transporter candidates and comprehensive in vivo analyses of sucrose concentration in plants. Since FLIPsuc-90μ also detects trehalose in animal cells, the new series of sensors will likely be suitable for investigating trehalose transport and monitor trehalose steady-state levels in vivo.
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Affiliation(s)
- Mayuri Sadoine
- Institute for Molecular Physiology, Heinrich Heine University Düsseldorf, Düsseldorf 40225, Germany
| | - Mira Reger
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, United States
| | - Ka Man Wong
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, United States
| | - Wolf B. Frommer
- Institute for Molecular Physiology, Heinrich Heine University Düsseldorf, Düsseldorf 40225, Germany
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, United States
- Institute for Transformative Biomolecules, ITbM, Nagoya University, Nagoya, Aichi 464-8601, Japan
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2
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Structural and evolutionary approaches to the design and optimization of fluorescence-based small molecule biosensors. Curr Opin Struct Biol 2019; 57:31-38. [DOI: 10.1016/j.sbi.2019.01.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/10/2019] [Accepted: 01/23/2019] [Indexed: 11/21/2022]
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3
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Slocum JD, Palmer AE, Jimenez R. Intramolecular Fluorescent Protein Association in a Class of Zinc FRET Sensors Leads to Increased Dynamic Range. J Phys Chem B 2019; 123:3079-3085. [PMID: 30942588 DOI: 10.1021/acs.jpcb.9b02479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Genetically encoded Förster resonance energy transfer (FRET) sensors enable the visualization of ions, molecules, and processes in live cells. However, despite their widespread use, the molecular states that determine sensor performance are usually poorly understood, which limits efforts to improve them. We used dynamic light scattering (DLS) and time-resolved fluorescence anisotropy to uncover the sensing mechanism of ZifCV1.173, a Zn2+ FRET sensor. We found that the dynamic range (DR) of ZifCV1.173 was dominated by the high FRET efficiency of the Zn2+-free state, in which the donor and acceptor fluorescent proteins were closely associated. Mutating the donor-acceptor interface revealed that the DR of ZifCV1.173 could be increased or decreased by promoting or disrupting the donor-acceptor interaction, respectively. Adapting the same mutations to a related sensor showed the same pattern of DR tuning, supporting our sensing mechanism and suggesting that DLS and time-resolved fluorescence anisotropy might be generally useful in the biophysical characterization of other FRET sensors.
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4
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Steel H, Papachristodoulou A. Probing Intercell Variability Using Bulk Measurements. ACS Synth Biol 2018; 7:1528-1537. [PMID: 29799736 DOI: 10.1021/acssynbio.8b00014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The measurement of noise is critical when assessing the design and function of synthetic biological systems. Cell-to-cell variability can be quantified experimentally using single-cell measurement techniques such as flow cytometry and fluorescent microscopy. However, these approaches are costly and impractical for high-throughput parallelized experiments, which are frequently conducted using plate-reader devices. In this paper we describe reporter systems that allow estimation of the cell-to-cell variability in a biological system's output using only measurements of a cell culture's bulk properties. We analyze one potential implementation of such a system that is based upon a fluorescent protein FRET reporter pair, finding that with typical parameters from the literature it is able to reliably estimate variability. We also briefly describe an alternate implementation based upon an activating sRNA circuit. The feasible region of parameter values for which the reporter system can function is assessed, and the dependence of its performance on both extrinsic and intrinsic noise is investigated. Experimental realization of these constructs can yield novel reporter systems that allow measurement of a synthetic gene circuit's output, as well as the intrapopulation variability of this output, at little added cost.
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Affiliation(s)
- Harrison Steel
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, U.K
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5
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Mastop M, Bindels DS, Shaner NC, Postma M, Gadella TWJ, Goedhart J. Characterization of a spectrally diverse set of fluorescent proteins as FRET acceptors for mTurquoise2. Sci Rep 2017; 7:11999. [PMID: 28931898 PMCID: PMC5607329 DOI: 10.1038/s41598-017-12212-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 09/05/2017] [Indexed: 01/13/2023] Open
Abstract
The performance of Förster Resonance Energy Transfer (FRET) biosensors depends on brightness and photostability, which are dependent on the characteristics of the fluorescent proteins that are employed. Yellow fluorescent protein (YFP) is often used as an acceptor but YFP is prone to photobleaching and pH changes. In this study, we evaluated the properties of a diverse set of acceptor fluorescent proteins in combination with the optimized CFP variant mTurquoise2 as the donor. To determine the theoretical performance of acceptors, the Förster radius was determined. The practical performance was determined by measuring FRET efficiency and photostability of tandem fusion proteins in mammalian cells. Our results show that mNeonGreen is the most efficient acceptor for mTurquoise2 and that the photostability is better than SYFP2. The non-fluorescent YFP variant sREACh is an efficient acceptor, which is useful in lifetime-based FRET experiments. Among the orange and red fluorescent proteins, mCherry and mScarlet-I are the best performing acceptors. Several new pairs were applied in a multimolecular FRET based sensor for detecting activation of a heterotrimeric G-protein by G-protein coupled receptors. Overall, the sensor with mNeonGreen as acceptor and mTurquoise2 as donor showed the highest dynamic range in ratiometric FRET imaging experiments with the G-protein sensor.
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Affiliation(s)
- Marieke Mastop
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL-1090 GE, Amsterdam, The Netherlands
| | - Daphne S Bindels
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL-1090 GE, Amsterdam, The Netherlands
| | - Nathan C Shaner
- Department of Photobiology and Bioimaging, The Scintillon Institute, San Diego, California, United States of America
| | - Marten Postma
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL-1090 GE, Amsterdam, The Netherlands
| | - Theodorus W J Gadella
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL-1090 GE, Amsterdam, The Netherlands
| | - Joachim Goedhart
- Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, P.O. Box 94215, NL-1090 GE, Amsterdam, The Netherlands.
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6
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Slyngborg M, Nielsen DA, Fojan P. The Physical Properties and Self-Assembly Potential of the RFFFR Peptide. Chembiochem 2016; 17:2083-2092. [PMID: 27581944 DOI: 10.1002/cbic.201600383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Indexed: 12/22/2022]
Abstract
The self-assembly of fibers from peptides has attracted a tremendous amount of attention due to its many applications, such as in drug-delivery systems, in tissue engineering, and in electronic devices. Recently, the self-assembly potential of the designer peptide RFFFR has been reported. Here it is experimentally verified that the peptide forms fibers that are entangled and form solid spheres without water inside. Upon dilution below the critical fiber concentration, the fibers untangle and become totally separated prior to dissolution. These structures readily bind thioflavin T, resulting in a characteristic change in fluorescent properties consistent with β-sheet-rich amyloid structures with aromatic/hydrophobic grooves. The circular dichroism spectroscopy data are dominated by a π→π* transition, thus indicating that the fibers are stabilized by π-stacking. Contrary to what was expected, the dissolution of the spheres/fibers results in increasing fluorescence anisotropy over time. This is explained in terms of HomoFRET between phenylalanine residues with a T-shaped π-stacking mode, which was determined in another study to be the dominant mode through atomistic simulations and semiempirical calculations. Kelvin probe force microscopy measurements indicate that the spheres and fibers have a conductivity comparable to that of gold. Hence, these self-assembled structures might be applicable in organic solid-state electronic devices. The dissolution properties of the spheres further suggest that they might be used as drug-delivery systems.
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Affiliation(s)
- Morten Slyngborg
- Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4 A, 9220, Aalborg Øst, Denmark
| | - Dennis Achton Nielsen
- Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4 A, 9220, Aalborg Øst, Denmark
| | - Peter Fojan
- Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4 A, 9220, Aalborg Øst, Denmark.
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A Guide to Fluorescent Protein FRET Pairs. SENSORS 2016; 16:s16091488. [PMID: 27649177 PMCID: PMC5038762 DOI: 10.3390/s16091488] [Citation(s) in RCA: 272] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/23/2016] [Accepted: 08/25/2016] [Indexed: 12/20/2022]
Abstract
Förster or fluorescence resonance energy transfer (FRET) technology and genetically encoded FRET biosensors provide a powerful tool for visualizing signaling molecules in live cells with high spatiotemporal resolution. Fluorescent proteins (FPs) are most commonly used as both donor and acceptor fluorophores in FRET biosensors, especially since FPs are genetically encodable and live-cell compatible. In this review, we will provide an overview of methods to measure FRET changes in biological contexts, discuss the palette of FP FRET pairs developed and their relative strengths and weaknesses, and note important factors to consider when using FPs for FRET studies.
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8
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Aper SJ, Merkx M. Rewiring Multidomain Protein Switches: Transforming a Fluorescent Zn(2+) Sensor into a Light-Responsive Zn(2+) Binding Protein. ACS Synth Biol 2016; 5:698-709. [PMID: 27031076 DOI: 10.1021/acssynbio.6b00027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Protein-based sensors and switches provide attractive tools for the real-time monitoring and control of molecular processes in complex biological environments. Fluorescent sensor proteins have been developed for a wide variety of small molecules, but the construction of genetically encoded light-responsive ligand binding proteins remains mostly unexplored. Here we present a generic approach to reengineer a previously developed FRET-based Zn(2+) sensor into a light-activatable Zn(2+) binding protein using a design strategy based on mutually exclusive domain interactions. These so-called VividZn proteins consist of two light-responsive Vivid domains that homodimerize upon illumination with blue light, thus preventing the binding of Zn(2+) between two Zn(2+) binding domains, Atox1 and WD4. Following optimization of the linker between WD4 and the N-terminus of one of the Vivid domains, VividZn variants were obtained that show a 9- to 55-fold decrease in Zn(2+) affinity upon illumination, which is fully reversible following dark adaptation. The Zn(2+) affinities of the switch could be rationally tuned between 1 pM and 2 nM by systematic variation of linker length and mutation of one of the Zn(2+) binding residues. Similarly, introduction of mutations in the Vivid domains allowed tuning of the switching kinetics between 10 min and 7 h. Low expression levels in mammalian cells precluded the demonstration of light-induced perturbation of cytosolic Zn(2+) levels. Nonetheless, our results firmly establish the use of intramolecular Vivid dimerization as an attractive light-sensitive input module to rationally engineer light-responsive protein switches based on mutually exclusive domain interactions.
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Affiliation(s)
- Stijn J.A. Aper
- Laboratory
of Chemical Biology
and Institute for Complex Molecular Systems (ICMS), Department of
Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Maarten Merkx
- Laboratory
of Chemical Biology
and Institute for Complex Molecular Systems (ICMS), Department of
Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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9
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Arts R, den Hartog I, Zijlema SE, Thijssen V, van der Beelen SHE, Merkx M. Detection of Antibodies in Blood Plasma Using Bioluminescent Sensor Proteins and a Smartphone. Anal Chem 2016; 88:4525-32. [PMID: 27018236 DOI: 10.1021/acs.analchem.6b00534] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Antibody detection is of fundamental importance in many diagnostic and bioanalytical assays, yet current detection techniques tend to be laborious and/or expensive. We present a new sensor platform (LUMABS) based on bioluminescence resonance energy transfer (BRET) that allows detection of antibodies directly in solution using a smartphone as the sole piece of equipment. LUMABS are single-protein sensors that consist of the blue-light emitting luciferase NanoLuc connected via a semiflexible linker to the green fluorescent acceptor protein mNeonGreen, which are kept close together using helper domains. Binding of an antibody to epitope sequences flanking the linker disrupts the interaction between the helper domains, resulting in a large decrease in BRET efficiency. The resulting change in color of the emitted light from green-blue to blue can be detected directly in blood plasma, even at picomolar concentrations of antibody. Moreover, the modular architecture of LUMABS allows changing of target specificity by simple exchange of epitope sequences, as demonstrated here for antibodies against HIV1-p17, hemagglutinin (HA), and dengue virus type I. The combination of sensitive ratiometric bioluminescent detection and the intrinsic modularity of the LUMABS design provides an attractive generic platform for point-of-care antibody detection that avoids the complex liquid handling steps associated with conventional immunoassays.
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Affiliation(s)
- Remco Arts
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Ilona den Hartog
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Stefan E Zijlema
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Vito Thijssen
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Stan H E van der Beelen
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Maarten Merkx
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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10
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Van de Wiel S, Merkx M, Van de Graaf S. Real Time Monitoring of Intracellular Bile Acid Dynamics Using a Genetically Encoded FRET-based Bile Acid Sensor. J Vis Exp 2016. [PMID: 26780506 DOI: 10.3791/53659] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Förster Resonance Energy Transfer (FRET) has become a powerful tool for monitoring protein folding, interaction and localization in single cells. Biosensors relying on the principle of FRET have enabled real-time visualization of subcellular signaling events in live cells with high temporal and spatial resolution. Here, we describe the application of a genetically encoded Bile Acid Sensor (BAS) that consists of two fluorophores fused to the farnesoid X receptor ligand binding domain (FXR-LBD), thereby forming a bile acid sensor that can be activated by a large number of bile acids species and other (synthetic) FXR ligands. This sensor can be targeted to different cellular compartments including the nucleus (NucleoBAS) and cytosol (CytoBAS) to measure bile acid concentrations locally. It allows rapid and simple quantitation of cellular bile acid influx, efflux and subcellular distribution of endogenous bile acids without the need for labeling with fluorescent tags or radionuclei. Furthermore, the BAS FRET sensors can be useful for monitoring FXR ligand binding. Finally, we show that this FRET biosensor can be combined with imaging of other spectrally distinct fluorophores. This allows for combined analysis of intracellular bile acid dynamics and i) localization and/or abundance of proteins of interest, or ii) intracellular signaling in a single cell.
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Affiliation(s)
- Sandra Van de Wiel
- Tytgat Institute for Liver and Intestinal Research, Department of Gastroenterology and Hepatology, Academic Medical Center
| | - Maarten Merkx
- Laboratory of Chemical Biology, Institute of Complex Molecular Systems (ICMS); Department of Biomedical Engineering, Eindhoven University of Technology
| | - Stan Van de Graaf
- Tytgat Institute for Liver and Intestinal Research, Department of Gastroenterology and Hepatology, Academic Medical Center;
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Shen Y, Lai T, Campbell RE. Red fluorescent proteins (RFPs) and RFP-based biosensors for neuronal imaging applications. NEUROPHOTONICS 2015; 2:031203. [PMID: 26158012 PMCID: PMC4478792 DOI: 10.1117/1.nph.2.3.031203] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 05/19/2015] [Indexed: 05/23/2023]
Abstract
The inherent advantages of red-shifted fluorescent proteins and fluorescent protein-based biosensors for the study of signaling processes in neurons and other tissues have motivated the development of a plethora of new tools. Relative to green fluorescent proteins (GFPs) and other blue-shifted alternatives, red fluorescent proteins (RFPs) provide the inherent advantages of lower phototoxicity, lower autofluorescence, and deeper tissue penetration associated with longer wavelength excitation light. All other factors being the same, the multiple benefits of using RFPs make these tools seemingly ideal candidates for use in neurons and, ultimately, the brain. However, for many applications, the practical utility of RFPs still falls short of the preferred GFPs. We present an overview of RFPs and RFP-based biosensors, with an emphasis on their reported applications in neuroscience.
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Affiliation(s)
- Yi Shen
- University of Alberta, Department of Chemistry, Edmonton, Alberta T6G 2G2, Canada
| | - Tiffany Lai
- University of Alberta, Department of Chemistry, Edmonton, Alberta T6G 2G2, Canada
| | - Robert E. Campbell
- University of Alberta, Department of Chemistry, Edmonton, Alberta T6G 2G2, Canada
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12
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Nettles CB, Hu J, Zhang D. Using Water Raman Intensities To Determine the Effective Excitation and Emission Path Lengths of Fluorophotometers for Correcting Fluorescence Inner Filter Effect. Anal Chem 2015; 87:4917-24. [DOI: 10.1021/acs.analchem.5b00513] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Charles B. Nettles
- Department
of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Juan Hu
- Department
of Mathematical Sciences, DePaul University, Chicago, Illinois 60604, United States
| | - Dongmao Zhang
- Department
of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
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