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Ensslen T, Behrends JC. A chip-based array for high-resolution fluorescence characterization of free-standing horizontal lipid membranes under voltage clamp. LAB ON A CHIP 2022; 22:2902-2910. [PMID: 35839072 DOI: 10.1039/d2lc00357k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Optical techniques, such as fluorescence microscopy, are of great value in characterizing the structural dynamics of membranes and membrane proteins. A particular challenge is to combine high-resolution optical measurements with high-resolution voltage clamp electrical recordings providing direct information on e.g. single ion channel gating and/or membrane capacitance. Here, we report on a novel chip-based array device which facilitates optical access with water or oil-immersion objectives of high numerical aperture to horizontal free-standing lipid membranes while controlling membrane voltage and recording currents using individual micropatterned Ag/AgCl-electrodes. Wide-field and confocal imaging, as well as time-resolved single photon counting on free-standing membranes spanning sub-nanoliter cavities are demonstrated while electrical signals, including single channel activity, are simultaneously acquired. This optically addressable microelectrode cavity array will allow combined electrical-optical studies of membranes and membrane proteins to be performed as a routine experiment.
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Affiliation(s)
- Tobias Ensslen
- Laboratory for Membrane Physiology and Technology, Department of Physiology, Faculty of Medicine, University of Freiburg, Hermann-Herder-Str. 7, 79104 Freiburg, Germany.
| | - Jan C Behrends
- Laboratory for Membrane Physiology and Technology, Department of Physiology, Faculty of Medicine, University of Freiburg, Hermann-Herder-Str. 7, 79104 Freiburg, Germany.
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2
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Weatherill EE, Wallace MI. Combining Single-Molecule Imaging and Single-Channel Electrophysiology. J Mol Biol 2015; 427:146-57. [DOI: 10.1016/j.jmb.2014.07.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/07/2014] [Accepted: 07/07/2014] [Indexed: 12/29/2022]
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3
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Ide T. Simultaneous Optical and Electrical Recording of Single Molecule Bonding to Single Channel Proteins. Chemphyschem 2010; 11:3408-11. [DOI: 10.1002/cphc.201000560] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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4
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Heron AJ, Thompson JR, Cronin B, Bayley H, Wallace MI. Simultaneous Measurement of Ionic Current and Fluorescence from Single Protein Pores. J Am Chem Soc 2009; 131:1652-3. [DOI: 10.1021/ja808128s] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrew J. Heron
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - James R. Thompson
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - Bríd Cronin
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - Hagan Bayley
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - Mark I. Wallace
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
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5
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Bayley H, Cronin B, Heron A, Holden MA, Hwang WL, Syeda R, Thompson J, Wallace M. Droplet interface bilayers. MOLECULAR BIOSYSTEMS 2008; 4:1191-208. [PMID: 19396383 DOI: 10.1039/b808893d] [Citation(s) in RCA: 355] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Droplet interface bilayers (DIBs) provide a superior platform for the biophysical analysis of membrane proteins. The versatile DIBs can also form networks, with features that include built-in batteries and sensors.
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Affiliation(s)
- Hagan Bayley
- Department of Chemistry, University of Oxford, Oxford, UK.
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6
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Heron AJ, Thompson JR, Mason AE, Wallace MI. Direct Detection of Membrane Channels from Gels Using Water-in-Oil Droplet Bilayers. J Am Chem Soc 2007; 129:16042-7. [DOI: 10.1021/ja075715h] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrew J. Heron
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - James R. Thompson
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Amy E. Mason
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
| | - Mark I. Wallace
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
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7
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de Planque MRR, de Planque MRR, Mendes GP, Zagnoni M, Sandison ME, Fisher KH, Berry RM, Watts A, Morgan H. Controlled delivery of membrane proteins to artificial lipid bilayers by nystatin-ergosterol modulated vesicle fusion. ACTA ACUST UNITED AC 2006; 153:21-30. [PMID: 16671820 DOI: 10.1049/ip-nbt:20050039] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The study of ion channels and other membrane proteins and their potential use as biosensors and drug screening targets require their reconstitution in an artificial membrane. These applications would greatly benefit from microfabricated devices in which stable artificial lipid bilayers can be rapidly and reliably formed. However, the amount of protein delivered to the bilayer must be carefully controlled. A vesicle fusion technique is investigated where composite ion channels of the polyene antibiotic nystatin and the sterol ergosterol are employed to render protein-carrying vesicles fusogenic. After fusion with an ergosterol-free artificial bilayer, the nystatin-ergosterol channels do not dissociate immediately and thus cause a transient current signal that marks the vesicle fusion event. Experimental pitfalls of this method were identified, the influence of the nystatin and ergosterol concentration on the fusion rate and the shape of the fusion event marker was explored, and the number of different lipid species was reduced. Under these conditions, the -amyloid peptide could be delivered in a controlled manner to a standard planar bilayer. Additionally, electrical recordings were obtained of vesicles fusing with a planar lipid bilayer in a microfabricated device, demonstrating the suitability of nystatin-ergosterol modulated vesicle fusion for protein delivery within microsystems.
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Affiliation(s)
- M R R de Planque
- University of Oxford, Bionanotechnology IRC, Clarendon Laboratory, Department of Physics, Oxford, UK.
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8
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Borisenko V, Lougheed T, Hesse J, Füreder-Kitzmüller E, Fertig N, Behrends JC, Woolley GA, Schütz GJ. Simultaneous optical and electrical recording of single gramicidin channels. Biophys J 2003; 84:612-22. [PMID: 12524314 PMCID: PMC1302642 DOI: 10.1016/s0006-3495(03)74881-4] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We report here an approach for simultaneous fluorescence imaging and electrical recording of single ion channels in planar bilayer membranes. As a test case, fluorescently labeled (Cy3 and Cy5) gramicidin derivatives were imaged at the single-molecule level using far-field illumination and cooled CCD camera detection. Gramicidin monomers were observed to diffuse in the plane of the membrane with a diffusion coefficient of 3.3 x 10(-8) cm(2)s(-1). Simultaneous electrical recording detected gramicidin homodimer (Cy3/Cy3, Cy5/Cy5) and heterodimer (Cy3/Cy5) channels. Heterodimer formation was observed optically by the appearance of a fluorescence resonance energy transfer (FRET) signal (irradiation of Cy3, detection of Cy5). The number of FRET signals was significantly smaller than the number of Cy3 signals (Cy3 monomers plus Cy3 homodimers) as expected. The number of FRET signals increased with increasing channel activity. In numerous cases the appearance of a FRET signal was observed to correlate with a channel opening event detected electrically. The heterodimers also diffused in the plane of the membrane with a diffusion coefficient of 3.0 x 10(-8) cm(2)s(-1). These experiments demonstrate the feasibility of simultaneous optical and electrical detection of structural changes in single ion channels as well as suggesting strategies for improving the reliability of such measurements.
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Affiliation(s)
- V Borisenko
- Department of Chemistry, University of Toronto, Canada
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9
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Ide T, Takeuchi Y, Aoki T, Yanagida T. Simultaneous optical and electrical recording of a single ion-channel. THE JAPANESE JOURNAL OF PHYSIOLOGY 2002; 52:429-34. [PMID: 12533247 DOI: 10.2170/jjphysiol.52.429] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In recent years, the single-molecule imaging technique has proven to be a valuable tool in solving many basic problems in biophysics. The technique used to measure single-molecule functions was initially developed to study electrophysiological properties of channel proteins. However, the technology to visualize single channels at work has not received as much attention. In this study, we have for the first time, simultaneously measured the optical and electrical properties of single-channel proteins. The large conductance calcium-activated potassium channel (BK-channel) labeled with fluorescent dye molecules was incorporated into a planar bilayer membrane and the fluorescent image captured with a total internal reflection fluorescence microscope simultaneously with single-channel current recording. This innovative technology will greatly advance the study of channel proteins as well as signal transduction processes that involve ion permeation processes.
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Affiliation(s)
- Toru Ide
- Single Molecule Processes Project, International Cooperative Research Project, Japan Science and Technology Corporation, Mino, 562-0035 Japan.
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10
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Abstract
The state of the art technology for the study of ion channels is the patch clamp technique. Ion channels mediate electrical current flow, have crucial roles in cellular physiology, and are important drug targets. The most popular (whole cell) variant of the technique detects the ensemble current over the entire cell membrane. Patch clamping is still a laborious process, requiring a skilled experimenter to micromanipulate a glass pipette under a microscope to record from one cell at a time. Here we report on a planar, microstructured quartz chip for whole cell patch clamp measurements without micromanipulation or visual control. A quartz substrate of 200 microm thickness is perforated by wet etching techniques resulting in apertures with diameters of approximately 1 microm. The apertures replace the tip of glass pipettes commonly used for patch clamp recording. Cells are positioned onto the apertures from suspension by application of suction. Whole cell recordings from different cell types (CHO, N1E-115 neuroblastoma) are performed with microstructured chips studying K(+) channels and voltage gated Ca(2+) channels.
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Affiliation(s)
- Niels Fertig
- Center for NanoScience and Sektion Physik, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539 Munich, Germany.
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11
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Hinterdorfer P, Schütz G, Kienberger F, Schindler H. Detection and characterization of single biomolecules at surfaces. J Biotechnol 2001; 82:25-35. [PMID: 11999710 DOI: 10.1016/s1389-0352(01)00030-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The investigation of bio-molecules has entered a new age since the development of methodologies capable of studies at the level of single molecules. In biology, most molecules show a complex dynamical behavior, with individual motions and transitions between different states, occurring as highly correlated in space and time within an arrangement of various elements. In order to resolve such dynamical changes in ensemble average techniques, one would have to synchronize all molecules, which is hard to achieve and might interfere with important system properties. Single molecule studies, in contrast, do not require pretreatment of the system and resume, therefore, much less invasive methodologies. Here, we review recent employments for the investigation of bio-molecules on surfaces, in which the high local and temporal resolution of two complementary techniques, atomic force microscopy and single molecule fluorescence microscopy, is used to address single molecules. Novel methodologies for the characterization of biologically relevant parameters, functions and dynamical aspects of individual molecules are described.
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12
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Lougheed T, Borisenko V, Hand CE, Woolley GA. Fluorescent gramicidin derivatives for single-molecule fluorescence and ion channel measurements. Bioconjug Chem 2001; 12:594-602. [PMID: 11459465 DOI: 10.1021/bc010006t] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single-molecule spectroscopies in combination with single-channel patch-clamp measurements have the potential for providing new information on ion channel gating processes. Fluorescent gramicidin derivatives could provide a means for calibrating such experiments since the structure of the open channel is known and the mechanism of gating (peptide dimerization) is generally agreed. We describe here the synthesis and characterization of two pairs of gramicidin derivatives that should prove useful for such studies. They contain robust fluorophores, undergo resonance energy transfer (FRET) when they dimerize, and have single-channel properties close to those of the wild-type channel.
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Affiliation(s)
- T Lougheed
- Department of Chemistry, 80 St. George Street, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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13
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Schütz GJ, Sonnleitner M, Hinterdorfer P, Schindler H. Single molecule microscopy of biomembranes (review). Mol Membr Biol 2000; 17:17-29. [PMID: 10824735 DOI: 10.1080/096876800294452] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Recent advances in the development of new microscopy techniques with a sensitivity of a single molecule have gained access to essentially new types of information obtainable from imaging biomolecular samples. These methodologies are analysed here in terms of their applicability to the in vivo visualization of cellular processes on the molecular scale, in particular of processes in cell membranes. First examples of single molecule microscopy on cell membranes revealed new basic insight into the lateral organization of the plasma membrane, providing the captivating perspective of an ultrasensitive methodology as a general tool to study local processes and heterogeneities in living cells.
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Affiliation(s)
- G J Schütz
- Institute for Biophysics, University of Linz, Austria
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14
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Abstract
One frontier challenge in microscopy and analytical chemistry is the analysis of soft matter at the single molecule level with biological systems as most complex examples. Towards this goal we have developed two novel microscopy methods. Both employ highly specific molecular recognition schemes used by nature-the recognition of specific protein sites by antibodies and ligands. One method uses fluorescence labeled ligands for detecting single molecules in fluid systems like membranes (Fig. 1B). Unitary signals are reliably resolved even for millisecond illumination periods. The knowledge of the unitary signal from single molecules permits the determination of stoichiometries of component association (Fig. 3). Direct imaging of the diffusional path of single molecules became possible for the first time (Fig. 4). Using linear polarized excitation, the angular orientation of single molecules can be analyzed (single molecule linear dichroism, (Fig. 5), which opens a new perspective for detecting conformational changes of single biomolecules. In the other method, an antibody is flexibly linked to the tip of an atomic-force microscope. This permits the identification of receptors in multi-component systems. Molecular mapping of biosurfaces and the study of molecular dynamics in the ms to s range become possible with atomic force microscopy.
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Affiliation(s)
- T Schmidt
- Institute for Biophysics, University of Linz, Austria
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15
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Duclohier H, Helluin O, Lea E, Mackie AR, Ladha S. Coupling Optical and Electrical Measurements in Artificial Membranes: Lateral Diffusion of Lipids and Channel Forming Peptides in Planar Bilayers. Biol Proced Online 1998; 1:81-91. [PMID: 12734600 PMCID: PMC140112 DOI: 10.1251/bpo10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/1998] [Indexed: 11/23/2022] Open
Abstract
Planar lipid bilayers (PLB) were prepared by the Montal-Mueller technique in a FRAP system designed to simultaneously measure conductivity across, and lateral diffusion of, the bilayer. In the first stage of the project the FRAP system was used to characterise the lateral dynamics of bilayer lipids with regards to phospholipid composition (headgroup, chain unsaturation etc.), presence of cholesterol and the effect of divalent cations on negatively-charged bilayers. In the second stage of the project, lateral diffusion of two fluorescently-labelled voltage-dependent pore-forming peptides (alamethicin and S4s from Shaker K(+) channel) was determined at rest and in the conducting state. This study demonstrates the feasibility of such experiments with PLBs, amenable to physical constraints, and thus offers new opportunities for systematic studies of structure-function relationships in membrane-associating molecules.
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Affiliation(s)
- H Duclohier
- UMR 6522 CNRS-Université de Rouen. Bd M. de Broglie, 76821 Mont-Saint-Aignan. France.School of Biological Sciences. University of East Anglia, Norwich NR4 7TJ, England. Present Address: The Johnson Research Foundation for Molecular Biophysics and Structural Biology, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059. USA.Institute of Food Research. BBSRC, Colney Research Park, Norwich NR4 7UA. England.
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16
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Ladha S, Mackie AR, Harvey LJ, Clark DC, Lea EJ, Brullemans M, Duclohier H. Lateral diffusion in planar lipid bilayers: a fluorescence recovery after photobleaching investigation of its modulation by lipid composition, cholesterol, or alamethicin content and divalent cations. Biophys J 1996; 71:1364-73. [PMID: 8874012 PMCID: PMC1233605 DOI: 10.1016/s0006-3495(96)79339-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
In spite of the fact that planar lipid bilayers are still the best-suited artificial membrane system for the study of reconstituted ion channels and receptors, data dealing with their physical characterization, especially as regards dynamics, are scanty. A combined electrical and optical chamber was designed and allowed fluorescence recovery after photobleaching recovery curves to be recorded from stable virtually solvent-free bilayers. D, the lateral diffusion coefficient of N-(7-nitrobenzoyl-2-oxa-1,3-diazol-4-yl)-1,2-dihexadecanoyl-sn- glycero-3-phosphoethanolamine, was found to be relatively insensitive to the phospholipid composition (headgroup, chain unsaturation, etc.), whereas inclusion of 33-50% cholesterol in the membrane reduced D by a factor of 2. Divalent cations significantly reduced D of negatively charged bilayers. These results compare well with data gathered on other model and natural systems. In addition, the incorporation of the voltage-dependent pore-former alamethicin did slightly reduce lipid lateral mobility. This study demonstrates the feasibility of such experiments with planar bilayers, which are amenable to physical constraints, and thus offers new opportunities for systematic studies of structure-function relationships in membrane-associating molecules.
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Affiliation(s)
- S Ladha
- Institute of Food Research, Norwich, England.
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17
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Warner IM, Soper SA, McGown LB. Molecular Fluorescence, Phosphorescence, and Chemiluminescence Spectrometry. Anal Chem 1996. [DOI: 10.1021/a19600045] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Isiah M. Warner
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, and Department of Chemistry, Duke University, Box 90346, Durham, North Carolina 27708-0346
| | - Steven A. Soper
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, and Department of Chemistry, Duke University, Box 90346, Durham, North Carolina 27708-0346
| | - Linda B. McGown
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, and Department of Chemistry, Duke University, Box 90346, Durham, North Carolina 27708-0346
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