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Horan ST, Gardner AR, Saager R, Durkin AJ, Venugopalan V. Recovery of layered tissue optical properties from spatial frequency-domain spectroscopy and a deterministic radiative transport solver. JOURNAL OF BIOMEDICAL OPTICS 2018; 24:1-11. [PMID: 30456934 PMCID: PMC6995875 DOI: 10.1117/1.jbo.24.7.071607] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/12/2018] [Indexed: 05/26/2023]
Abstract
We present a method to recover absorption and reduced scattering spectra for each layer of a two-layer turbid media from spatial frequency-domain spectroscopy data. We focus on systems in which the thickness of the top layer is less than the transport mean free path ( 0.1 - 0.8l * ) . We utilize an analytic forward solver, based upon the N'th-order spherical harmonic expansion with Fourier decomposition ( SHEFN ) method in conjunction with a multistage inverse solver. We test our method with data obtained using spatial frequency-domain spectroscopy with 32 evenly spaced wavelengths within λ = 450 to 1000 nm on six-layered tissue phantoms with distinct optical properties. We demonstrate that this approach can recover absorption and reduced scattering coefficient spectra for both layers with accuracy comparable with current Monte Carlo methods but with lower computational cost and potential flexibility to easily handle variations in parameters such as the scattering phase function or material refractive index. To our knowledge, this approach utilizes the most accurate deterministic forward solver used in such problems and can successfully recover properties from a two-layer media with superficial layer thicknesses.
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Affiliation(s)
- Sean T. Horan
- University of California, Department of Mathematics, Irvine, California, United States
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
| | - Adam R. Gardner
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
- University of California, Department of Chemical Engineering and Materials Science, Irvine, California, United States
| | - Rolf Saager
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
| | - Anthony J. Durkin
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
- University of California, Department of Biomedical Engineering, Irvine, California, United States
| | - Vasan Venugopalan
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
- University of California, Department of Chemical Engineering and Materials Science, Irvine, California, United States
- University of California, Department of Biomedical Engineering, Irvine, California, United States
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2
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Tonello L, Gashi B, Scuotto A, Cappello G, Cocchi M, Gabrielli F, Tuszynski JA. The gastrointestinal-brain axis in humans as an evolutionary advance of the root-leaf axis in plants: A hypothesis linking quantum effects of light on serotonin and auxin. J Integr Neurosci 2018. [DOI: 10.3233/jin-170048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
| | - Bekim Gashi
- Department of Biology, University of Prishtina “Hasan Prishtina”, Prishtina, 10000, Kosovo
| | | | | | | | | | - Jack A. Tuszynski
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
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3
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Hackl C, Beyreiss R, Geissler D, Jezierski S, Belder D. Rapid prototyping of electrochromatography chips for improved two-photon excited fluorescence detection. Anal Chem 2014; 86:3773-9. [PMID: 24666258 DOI: 10.1021/ac500793e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present study, we introduce two-photon excitation at 532 nm for label-free fluorescence detection in chip electrochromatography. Two-photon excitation at 532 nm offers a promising alternative to one-photon excitation at 266 nm, as it enables the use of economic chip materials instead of fused silica. In order to demonstrate these benefits, one-photon and two-photon induced fluorescence detection are compared in different chip layouts and materials with respect to the achievable sensitivity in the detection of polycyclic aromatic hydrocarbons (PAHs). Customized chromatography chips with cover or bottom slides of different material and thickness are produced by means of a rapid prototyping method based on liquid-phase lithography. The design of thin bottom chips (180 μm) enables the use of high-performance immersion objectives with low working distances, which allows one to exploit the full potential of two-photon excitation for a sensitive detection. The developed method is applied for label-free analysis of PAHs separated on a polymer monolith inside polymer glass sandwich chips made from fused silica or soda-lime glass. The obtained limits of detection range from 40 nM to 1.95 μM, with similar sensitivities in fused silica thin bottom chips for one-photon and two-photon excitation. In deep-UV non- or less-transparent devices two-photon excitation is mandatory for label-free detection of aromatics with high sensitivity.
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Affiliation(s)
- Claudia Hackl
- Institut für Analytische Chemie, Universität Leipzig , Linnéstraße 3, 04103 Leipzig, Germany
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Beyreiss R, Geißler D, Ohla S, Nagl S, Posch TN, Belder D. Label-free fluorescence detection of aromatic compounds in chip electrophoresis applying two-photon excitation and time-correlated single-photon counting. Anal Chem 2013; 85:8150-7. [PMID: 23944704 DOI: 10.1021/ac4010937] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, we introduce time-resolved fluorescence detection with two-photon excitation at 532 nm for label-free analyte determination in microchip electrophoresis. In the developed method, information about analyte fluorescence lifetimes is collected by time-correlated single-photon counting, improving reliable peak assignment in electrophoretic separations. The determined limits of detection for serotonin, propranolol, and tryptophan were 51, 37, and 280 nM, respectively, using microfluidic chips made of fused silica. Applying two-photon excitation microchip separations and label-free detection could also be performed in borosilicate glass chips demonstrating the potential for label-free fluorescence detection in non-UV-transparent devices. Microchip electrophoresis with two-photon excited fluorescence detection was then applied for analyses of active compounds in plant extracts. Harmala alkaloids present in methanolic plant extracts from Peganum harmala could be separated within seconds and detected with on-the-fly determination of fluorescence lifetimes.
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Affiliation(s)
- Reinhild Beyreiss
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany
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5
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de Kort BJ, de Jong GJ, Somsen GW. Native fluorescence detection of biomolecular and pharmaceutical compounds in capillary electrophoresis: Detector designs, performance and applications: A review. Anal Chim Acta 2013; 766:13-33. [DOI: 10.1016/j.aca.2012.12.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Revised: 12/01/2012] [Accepted: 12/03/2012] [Indexed: 01/05/2023]
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6
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Johnson Retnaraj Samuel SC, Elaiya Raja S, Beryl Vedha Y, Edith Arul Jane A, Amutha K, Dinesh SM, Jackson Durairaj SC, Kalidas RM, Tharmaraj V, Pitchumani K, Sudhakar S. Autofluorescence in BrdU-positive cells and augmentation of regeneration kinetics by riboflavin. Stem Cells Dev 2012; 21:2071-83. [PMID: 22150027 DOI: 10.1089/scd.2011.0485] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The earthworm, Eudrilus eugeniae, has a prodigious ability to regenerate lost segments. The skin of the worm has an outermost epidermal layer followed by a thick circular muscle layer and an innermost thin longitudinal cell layer. During the process of regeneration, the circular muscle layer decreased in thickness, and longitudinal cell layer increased. The histological analysis of the regenerated worm shows that the longitudinal cell layer forms the regeneration blastema. BrdU-labeling retention assay confirmed that the circular muscle and longitudinal cell layers have BrdU-positive cells, which migrate from the adjacent segments to the regeneration blastema. In addition, it was noted that the cells of the earthworm, E. eugeniae, have the property of autofluorescence. Autofluorescence was found in the cytoplasm, but not in the nucleus. It has been also found that the major source for autofluorescence is riboflavin. Further, it was also demonstrated that supplementation with riboflavin increases the rate of regeneration, while regeneration was hampered by reduced levels of riboflavin. The importance of riboflavin in regeneration was also confirmed by rescue assay. In addition, it was also identified that BrdU-positive cells are highly fluorescent compared to the surrounding cells.
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7
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Gulcev MD, McGinitie TM, Bahnasy MF, Lucy CA. Surfactant bilayer coatings in narrow-bore capillaries in capillary electrophoresis. Analyst 2010; 135:2688-93. [DOI: 10.1039/c0an00279h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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Li Y, de Silva PG, Xi L, van Winkle A, Lin JJC, Ahmed S, Geng ML. Separation of flavins and nicotinamide cofactors in Chinese hamster ovary cells by capillary electrophoresis. Biomed Chromatogr 2009; 22:1374-84. [PMID: 18814195 DOI: 10.1002/bmc.1068] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Simultaneous extraction, separation and quantitation of reduced nicotinamide adenine dinucleotide (NADH), reduced nicotinamide adenine dinucleotide phosphate (NADPH), flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) in Chinese Hamster Ovary (CHO) cells were investigated. The separation of flavins and nicotinamide cofactors was performed by capillary electrophoresis with laser-induced fluorescence detection at the excitation wavelength of 325 nm. The separation protocol was established by investigating the excitation wavelength, high voltage and effects of buffer nature, pH and concentration. All endogenous fluorophores riboflavin, FAD, FMN, NADH and NADPH show wide linear range of quantitation. The limits of detection for the five compounds ranged from 4.5 to 23 nM. Extraction conditions were optimized for high-efficiency recovery of all endogenous fluorophores from CHO cells. To account for the complex matrix of cell extracts, a standard addition method was used to quantify FAD, FMN, NADH and NADPH in CHO cells. The quantitative results should be useful to reveal the metabolic status of cells. The protocols for extraction, separation and quantitation are readily adaptable to normal and cancer cell lines for the analysis of endogenous fluorophores.
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Affiliation(s)
- Ye Li
- Department of Chemistry and Center for Biocatalysis and Bioprocessing, University of Iowa, Iowa City, IA 52242, USA
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Northrop BH, Yang HB, Stang PJ. Coordination-driven self-assembly of functionalized supramolecular metallacycles. Chem Commun (Camb) 2008:5896-908. [PMID: 19030534 PMCID: PMC2621066 DOI: 10.1039/b811712h] [Citation(s) in RCA: 289] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Coordination-driven self-assembly that combines rigid ditopic Pt(II) metal acceptors and bis-pyridyl organic donors provides a facile means of synthesizing well-defined metallacycles of predetermined size and geometry. Functionalization of the component acceptor or donor building blocks allows for the preparation of multifunctional supramolecular materials wherein the stoichiometry and position of individual functional moieties can be precisely controlled. The design, self-assembly, and applications of polyfunctional supramolecules incorporating functional moieties with host-guest, photonic, materials, and self-organizational properties is discussed.
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Affiliation(s)
- Brian H Northrop
- University of Utah Department of Chemistry, 315 So. 1400 E., Salt Lake City, UT, USA.
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10
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Feng X, Chen S, Xu Y, Du W, Luo Q, Liu BF. Separation and determination of biogenic amines in fish using MEKC with novel multiphoton excitation fluorescence detection. J Sep Sci 2008; 31:824-8. [DOI: 10.1002/jssc.200700514] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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11
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Xu Y, Chen S, Feng X, Du W, Luo Q, Liu BF. On-column detection of multiphoton-excited fluorescence in CE using hyphenated cylindrical-square capillaries. Electrophoresis 2008; 29:734-9. [DOI: 10.1002/elps.200700238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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12
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Chen S, Xu Y, Xu F, Feng X, Du W, Luo Q, Liu BF. Separation and determination of amino acids by micellar electrokinetic chromatography coupling with novel multiphoton excited fluorescence detection. J Chromatogr A 2007; 1162:149-53. [PMID: 17560588 DOI: 10.1016/j.chroma.2007.05.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 05/14/2007] [Accepted: 05/14/2007] [Indexed: 11/29/2022]
Abstract
In this article, it was demonstrated that separation and determination of 20 amino acids were accomplished by micellar electrokinetic chromatography (MEKC) coupling with novel multiphoton excited fluorescence (MPEF) detection method. Different from MPEF achieved by expensive fs laser, continuous wave (CW) diode laser of ultra-low cost was uniquely employed in our MPEF system. Amino acids were fluorescently labeled with fluorescein isothiocyanate (FITC), and were subjected to sodium dodecyl sulfate (SDS)-based MEKC separation and CW-based MPEF detection. The result was compared with that by single photon excited fluorescence (SPEF), which indicated that MPEF had the advantages of better mass detectability and higher separation selectivity over SPEF. Quantitative analysis was performed and revealed linear dynamic range of over 2 orders of magnitude, with mass detection limit down to ymole level. To evaluate the reliability, this method was successfully applied for analyzing a commercial nutrition supplement liquid.
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Affiliation(s)
- Sheng Chen
- The Key Laboratory of Biomedical Photonics of MOE - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Department of Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
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13
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Du W, Chen S, Xu Y, Chen Z, Luo Q, Liu BF. Multiphoton excitation fluorescence: A versatile detection method for capillary electrophoresis. J Sep Sci 2007; 30:906-15. [PMID: 17536736 DOI: 10.1002/jssc.200600477] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Multiphoton excitation is a relatively old concept in quantum optics. But using multiphoton excitation fluorescence (MPEF) for bioanalysis is still in its infancy. Recently, MPEF has been introduced into the microseparation field, particularly CE, as a novel detection method. In this paper, MPEF detection for CE is reviewed, including MPEF fundamentals, approaches to achieving MPEF, detector configurations and applications in biological and environmental analyses. Emphasis will be placed on some recent advances of CE-MPEF in our laboratory. Challenges and future prospects are also discussed.
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Affiliation(s)
- Wei Du
- Key Laboratory of Biomedical Photonics of MOE, Hubei Bioinformatics, Department of Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
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14
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Mesitylene based azo-coupled chromogenic tripodal receptors—a visual detection of Ag(I) in aqueous medium. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.05.047] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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15
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Chen S, Liu BF, Fu L, Xiong T, Liu T, Zhang Z, Huang ZL, Lu Q, Zhao YD, Luo Q. Continuous wave-based multiphoton excitation fluorescence for capillary electrophoresis. J Chromatogr A 2006; 1109:160-6. [PMID: 16325835 DOI: 10.1016/j.chroma.2005.11.033] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Revised: 11/04/2005] [Accepted: 11/08/2005] [Indexed: 11/29/2022]
Abstract
It was reported that a novel detection method, continuous wave (CW)-based multiphoton excitation (MPE) fluorescence detection with diode laser (DL), has been firstly proposed for capillary electrophoresis (CE). Special design of end-column detection configuration proved to be superior to on-column type, considering the detection sensitivity. Three different kinds of fluorescent tags that were widely used as molecular label in bio-analysis, such as small-molecule dye, fluorescent protein and nano particle or also referred to as quantum dot (QD), have been evaluated as samples for the constructed detection scheme. Quantitative analyses were also performed using rhodamine species as tests, which revealed dynamic linear range over two orders of magnitude, with detection limit down to zeptomole-level. Simultaneous detection of fluorescent dyestuffs with divergent excitation and emission wavelengths in a broad range showed advantage of this scheme over conventional laser-induced fluorescence (LIF) detection. Further investigations on CW-MPE fluorescence detection with diode laser for capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) separations of fluorescein isothiocyanate (FITC) labeled amino acids indicated good prospect of this detection approach in various micro or nano-column liquid phase separation technologies.
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Affiliation(s)
- Sheng Chen
- Department of Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
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16
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Pobozy E, Michalski A, Sotowska-Brochocka J, Trojanowicz M. Determination of melatonin and its precursors and metabolites using capillary electrophoresis with UV and fluorometric detection. J Sep Sci 2005; 28:2165-72. [PMID: 16318213 DOI: 10.1002/jssc.200500095] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A micellar electrokinetic chromatography method has been developed for simultaneous determination of melatonin and its precursors and metabolites. A 20 mM borate buffer pH 9.5 with 50 mM SDS served as the electrolyte. Tryptophan, 5-methoxyindoleacetic acid, 6-hydroxymelatonin, melatonin, serotonin, and 5-methoxytryptamine were baseline separated in less than 13 min. The limits of detection for UV detection and fluorometric detection based on native fluorescence of analytes were at the sub-ppm level. The proposed method with UV detection was applied to melatonin content control in pharmaceutical tablets with a precision expressed as RSD (n = 7) = 1.6%. For biological samples extraction with chloroform and ethyl acetate was examined. With ethyl acetate and chloroform recoveries of 87.2% and 82.1% melatonin, respectively, were obtained from plasma samples. The recovery of melatonin from spiked urine samples was 80.0% for ethyl acetate and 82.5% for chloroform. Fluorometric detection provides about two-fold improvement over UV in the detection of melatonin and minor improvements for three other analytes, but is much poorer than UV for tryptophan and 6-hydroxymelatonin in applied conditions.
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Affiliation(s)
- Ewa Pobozy
- Department of Chemistry, University of Warsaw, Warsaw, Poland.
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Wise DD, Shear JB. Quantitation of nicotinamide and serotonin derivatives and detection of flavins in neuronal extracts using capillary electrophoresis with multiphoton-excited fluorescence. J Chromatogr A 2005; 1111:153-8. [PMID: 16569574 DOI: 10.1016/j.chroma.2005.07.067] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Revised: 06/30/2005] [Accepted: 07/04/2005] [Indexed: 10/25/2022]
Abstract
Capillary electrophoresis (CE) with multiphoton-excited fluorescence detection (CE-MPE) allows low-background analysis of spectrally distinct fluorophores using a single long-wavelength laser. Extracts were prepared from immortalized rat raphe nuclei neurons, and were analyzed by CE-MPE. Native fluorescence was detected from reduced nicotinamide adenine dinucleotide (NADH) and its phosphorylated form (NADPH), flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), riboflavin, serotonin, and 5-hydroxytryptophan (5HTrp). Quantitation of exogenous serotonin (taken up by cells) and endogenous NADH and 5HTrp was possible using internal standards or standard addition. This system should be useful to study monamine oxidase inhibitors (MAOIs) and selective serotonin reuptake inhibitors (SSRIs).
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Affiliation(s)
- Dana D Wise
- Department of Chemistry & Biochemistry, The University of Texas, Austin, 78712-0165, USA
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Johnson ME, Landers JP. Fundamentals and practice for ultrasensitive laser-induced fluorescence detection in microanalytical systems. Electrophoresis 2005; 25:3513-27. [PMID: 15565706 DOI: 10.1002/elps.200406086] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Laser-induced fluorescence is an extremely sensitive method for detection in chemical separations. In addition, it is well-suited to detection in small volumes, and as such is widely used for capillary electrophoresis and microchip-based separations. This review explores the detailed instrumental conditions required for sub-zeptomole, sub-picomolar detection limits. The key to achieving the best sensitivity is to use an excitation and emission volume that is matched to the separation system and that, simultaneously, will keep scattering and luminescence background to a minimum. We discuss how this is accomplished with confocal detection, 90 degrees on-capillary detection, and sheath-flow detection. It is shown that each of these methods have their advantages and disadvantages, but that all can be used to produce extremely sensitive detectors for capillary- or microchip-based separations. Analysis of these capabilities allows prediction of the optimal means of achieving ultrasensitive detection on microchips.
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Affiliation(s)
- Mitchell E Johnson
- Duquesne University, Department of Chemistry and Biochemistry, Pittsburgh, PA 15282, USA.
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Dad S, Bisby R, Clark I, Parker A. Identification and reactivity of the triplet excited state of 5-hydroxytryptophan. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2005; 78:245-51. [PMID: 15708522 PMCID: PMC1890304 DOI: 10.1016/j.jphotobiol.2004.11.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 11/22/2004] [Accepted: 11/22/2004] [Indexed: 11/28/2022]
Abstract
Both the neurotransmitter serotonin and the unnatural amino acid 5-hydroxytryptophan (5HT), contain the 5-hydroxyindole chromophore. The photochemistry of 5HT is being investigated in relation to the multiphoton excitation of this chromophore to produce a characteristic photoproduct with green fluorescence ('hyperluminescence'). Laser flash photolysis (308 nm) of 5HT in aqueous solution at neutral pH produces both the neutral 5-indoloxyl radical (lambda(max) 400-420 nm) and another transient absorption with lambda(max) 480 nm and lifetime of 2 micros in deaerated solutions. Based on quenching by oxygen and beta-carotene, the species at 480 nm is identified as the triplet excited state of 5HT. In acidic solution a new oxygen-insensitive intermediate with lambda(max) 460 is assigned to the radical cation of 5HT. Time-resolved measurements of luminescence at 1270 nm have shown that the triplet state of 5HT is able to react with oxygen to form singlet excited oxygen (1O2*) with a quantum yield of approximately 0.1. However, 5HT has also been found to be an effective quencher of singlet oxygen with a second order rate constant of 1.3 x 10(8) dm3 mol(-1) s(-1). The results are discussed in the light of recent observations on the multiphoton-excited photochemistry of serotonin.
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Affiliation(s)
- S. Dad
- Biosciences Research Institute, University of Salford, Salford M5 4WT, UK
| | - R.H. Bisby
- Biosciences Research Institute, University of Salford, Salford M5 4WT, UK
| | - I.P. Clark
- Lasers for Science Facility, CCLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
| | - A.W. Parker
- Lasers for Science Facility, CCLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
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Banthia S, Samanta A. A two-dimensional chromogenic sensor as well as fluorescence inverter: selective detection of copper(ii) in aqueous medium. NEW J CHEM 2005. [DOI: 10.1039/b504823k] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Fluorescence detection in capillary electrophoresis. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0166-526x(05)45006-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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22
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Wise DD, Shear JB. Circadian tracking of nicotinamide cofactor levels in an immortalized suprachiasmatic nucleus cell line. Neuroscience 2004; 128:263-8. [PMID: 15350639 DOI: 10.1016/j.neuroscience.2004.06.058] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2004] [Indexed: 10/26/2022]
Abstract
Nicotinamide adenine dinucleotides can exhibit a daily rhythm in plants and regulate the activity of mammalian clock-like transcription factors in vitro. Because one such redox-sensitive transcription factor is present in the master circadian clock of the brain (the suprachiasmatic nuclei, SCN) and the SCN exhibits a characteristic daily rhythm in glucose usage, nicotinamide cofactors might be expected to influence, exhibit, and/or reflect biological rhythms in SCN cells. Therefore, cofactors were extracted from a model SCN cell line at 3 h intervals over 1-2 day periods and samples were analyzed by capillary electrophoresis with multiphoton excitation of fluorescence. Natively fluorescent reduced cofactors (nicotinamide adenine dinucleotide, NADH, and its phosphorylated form, NADPH) were assayed directly, and nonfluorescent oxidized cofactors (nicotinamide adenine dinucleotide, NAD, and its phosphorylated form, NADP) were enzymatically reduced to their fluorescent counterparts before analysis. In the first day after a synchronizing pulse of fetal bovine serum, a dramatic upregulation in cellular NADH content was observed, consistent with a response to serum insulin; this was accompanied by a smaller decrease in NADPH redox state, which may indicate scavenging of reactive oxygen species generated by increased cellular metabolism. However, when cells were investigated after these early phenomena had recovered or stabilized, no circadian NAD(P)(H) rhythms were observed. During these studies, the NADH/NAD(H) concentration ratio in SCN2.2 cells (0.13+/-0.03) was not high enough to activate clock-like transcription factors. Although the NADPH/NADP(H) concentration ratio was more appropriate (0.8+/-0.1), the intracellular NADPH concentration was < or = 0.7 mM, far too low for half-maximal DNA binding of clock-like transcription factors in vitro. Moreover, these concentration and ratio values represent cellular averages, and free cofactors should be much lower in the cell nucleus. Our data show that SCN2.2 cells maintain nearly constant circadian NAD(P)(H) levels, and that the previously reported in vitro relationship between clock-like transcription factors and NAD(P)(H) does not appear to be biologically relevant.
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Affiliation(s)
- D D Wise
- Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station A5300, 78712-0165, USA
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Gostkowski ML, Allen R, Plenert ML, Okerberg E, Gordon MJ, Shear JB. Multiphoton-excited serotonin photochemistry. Biophys J 2004; 86:3223-9. [PMID: 15111435 PMCID: PMC1304187 DOI: 10.1016/s0006-3495(04)74370-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
We report photochemical and photophysical studies of a multiphoton-excited reaction of serotonin that previously has been shown to generate a photoproduct capable of emitting broadly in the visible spectral region. The current studies demonstrate that absorption of near-infrared light by an intermediate state prepared via three-photon absorption enhances the photoproduct formation yield, with the largest action cross sections ( approximately 10(-19) cm(2)) observed at the short-wavelength limit of the titanium:sapphire excitation source. The intermediate state is shown to persist for at least tens of nanoseconds and likely to be different from a previously reported oxygen-sensitive intermediate. In addition, the two-photon fluorescence action spectrum for the fluorescent photoproduct was determined and found to have a maximum at approximately 780 nm (3.2 eV). A general mechanism for this photochemical process is proposed.
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Affiliation(s)
- Michael L Gostkowski
- Department of Chemistry and Biochemistry, The Institute for Cellular and Molecular Biology, and The Center for Nano and Molecular Science and Technology, The University of Texas, Austin, Texas 78712, USA
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24
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Wise DD, Shear JB. Tracking variations in nicotinamide cofactors extracted from cultured cells using capillary electrophoresis with multiphoton excitation of fluorescence. Anal Biochem 2004; 326:225-33. [PMID: 15003563 DOI: 10.1016/j.ab.2003.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2003] [Indexed: 11/15/2022]
Abstract
Nicotinamide cofactors play numerous roles in cellular metabolic and biosynthetic reactions and intracellular signaling events. Recently, nicotinamide cofactors have been implicated in the function of cellular biological clocks. To gain insight into the possible roles of nicotinamide cofactors in complex time-related events, we have developed a rapid and sensitive method for extraction of NAD(P)(H) from cultured cells, separation of analytes by capillary electrophoresis, and detection by multiphoton excitation of fluorescence. Extraction and quantitation steps have been systematically characterized for optimal pH, detergent, temperature, sonication, filtration, efficiency, accuracy, and reproducibility. The method is suitable for extractions at 2- to 3-h intervals over 1 day or more or as frequently as every hour for shorter durations. Natively fluorescent NAD(P)H are assayed directly, and nonfluorescent NAD(P) are enzymatically reduced to their fluorescent counterparts before analysis. The method yields accurate values for cellular NADP, NADPH, and total NAD(H) levels and relative information on cellular NADH concentration; modification of the procedure allows full quantitation of all relevant species. We conclude that these assays are more suitable than any yet published for tracking variations in nicotinamide cofactor levels over periods of 1 day or more.
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Affiliation(s)
- Dana D Wise
- Department of Chemistry and Biochemistry and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
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Resendiz MJE, Noveron JC, Disteldorf H, Fischer S, Stang PJ. A Self-Assembled Supramolecular Optical Sensor for Ni(II), Cd(II), and Cr(III). Org Lett 2004; 6:651-3. [PMID: 14986941 DOI: 10.1021/ol035587b] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new chromogenic supramolecular sensor for transition metals is reported. It is based on a newly designed phenanthroline-containing molecule that self-assembles via an organometallic "clip" into a supramolecular optical sensor for metals. [reaction: see text]
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Affiliation(s)
- Marino J E Resendiz
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112, USA
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26
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Woods LA, Ewing AG. Etched electrochemical detection for electrophoresis in nanometer inner diameter capillaries. Chemphyschem 2003; 4:207-11. [PMID: 12619421 DOI: 10.1002/cphc.200390032] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Capillary electrophoresis in nanometer inner diameter capillaries allows for the analysis of extremely small volume samples, such as the contents of single cells. However, the utilization of these ultrasmall capillaries requires a very sensitive and low volume detector. An improved method for end-column amperometric detection for capillary electrophoresis in nanometer inner diameter (i.d.) capillaries is presented. This new method involves etching both the electrode and the detection end of the capillary. These design improvements allow for better alignment between the capillary bore and the electrode. As a result, dead volume in the detector is minimized. The etched method for electrochemical detection in ultrasmall capillaries provides average coulometric efficiencies of 70 +/- 10% for dopamine and 40 +/- 20% for catechol in 770 nm i.d. capillaries. Furthermore, this technique provides peak efficiencies as high as 100,000 theoretical plates and detection limits as low as 340 zmol for both dopamine and catechol.
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Affiliation(s)
- Lori A Woods
- Department of Chemistry, 152 Davey Laboratory, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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27
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Bisby RH, Arvanitidis M, Botchway SW, Clark IP, Parker AW, Tobin D. Investigation of multiphoton-induced fluorescence from solutions of 5-hydroxytryptophan. Photochem Photobiol Sci 2003; 2:157-62. [PMID: 12664978 DOI: 10.1039/b206848f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It is reported (J. B. S. Shear, C. Xu and W. W. Webb, Photochem. Photobiol. 1997, 65, 931) that multiphoton near infrared excitation of 5-hydroxytryptophan results in a transient product with green fluorescence. Visible fluorescence from multiphoton excitation enables detection of 5-hydroxytryptophan with extremely high sensitivity and also has potential applications in imaging of biological systems and investigation of protein dynamics. The characteristic fluorescence at 500 nm has now also been observed in a two laser experiment whereby 308 nm photolysis of the solution is followed by an excitation step at 430 nm. Fluorescence was observed in aerated and deaerated solutions and in the presence of ascorbate. Enhancement of fluorescence was observed on addition of ethanol. Transient absorption experiments with 308 nm photolysis showed the formation of three transient species. In the presence of ascorbate the radical formed by photoionisation was quenched, revealing a long-lived species (tau > 1 ms) with a similar absorption spectrum, which is ascribed to the fluorescing species. Fluorescence induced by multiphoton excitation had a lifetime of 910 +/- 10 ps and was also unaffected by ascorbate. In the presence of organic solvents there was an increase in fluorescence lifetime, but a decrease in overall fluorescence intensity. The fluorescence intensity and fluorescence lifetime both decreased in acidic solution (pH < 3). The results indicate that the fluorescence does not originate from the 5-indoxyl radical as previously suggested but from one or more other transient products which require further characterisation.
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Affiliation(s)
- Roger H Bisby
- Biosciences Research Institute, University of Salford, Salford, UK M5 4WT.
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28
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Gostkowski ML, Wei J, Okerberg E, Shear JB. Attomole electrophoretic analysis of catecholamines using copper-catalyzed intramolecular cyclization. Anal Biochem 2002; 303:199-202. [PMID: 11950220 DOI: 10.1006/abio.2001.5550] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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29
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Okerberg E, Shear JB. Neuropeptide Analysis Using Capillary Electrophoresis with Multiphoton-Excited Intrinsic Fluorescence Detection. Anal Biochem 2001; 292:311-3. [PMID: 11355869 DOI: 10.1006/abio.2001.5090] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- E Okerberg
- Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, USA
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30
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Molnár-Perl I. Advances in the analysis of tryptophan and its related compounds by chromatography. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 467:801-16. [PMID: 10721133 DOI: 10.1007/978-1-4615-4709-9_102] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Advances in the analysis of tryptophan,--(both in its free form and bound, alone or together with its metabolites),--has been compiled on the basis of the relevant papers published in the last 4-5 years, including author's experiences associated with the preparation of derivatives and with any of those conditions arising from the analytical procedure itself. The special requirements of various, tryptophan containing matrices were also taken into consideration (biological tissues or fluids, food and feed stuffs, etc). For the sake of completeness in addition to the most common HPLC/UV/F1 techniques, HPLC/MS, GC/MS, CE/UV/F1 and spectrophotometry will be also discussed.
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Affiliation(s)
- I Molnár-Perl
- Institute of Inorganic & Analytical Chemistry, L. Eötvös University, Budapest, Hungary.
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Gostkowski ML, Wei J, Shear JB. Measurements of serotonin and related indoles using capillary electrophoresis with multiphoton-induced hyperluminescence. Anal Biochem 1998; 260:244-50. [PMID: 9657885 DOI: 10.1006/abio.1998.2723] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report the use of multiphoton-excited photochemistry to generate highly fluorescent products from hydroxyindoles fractionated in submicron capillary electrophoresis channels. In this approach, the near-infrared (750 nm) output from a modelocked titanium:sapphire laser is focused at the outlet of a 0.6-micron i.d. capillary, producing pulse intensities of approximately 10(12) W cm-2 within a femtoliter focal volume. Hydroxyindole molecules migrating through the outlet aperture of the capillary intersect the beam focus, where absorption of three to four photons (approximately 1.65 eV photon-1) initiates a photobleaching reaction. The resultant hydroxyindole photoproducts produce broadband visible emission (lambdamax approximately 500 nm) when excited with two additional near-IR photons and appear substantially more resistant to photobleaching than the parent hydroxyindoles. This multiphoton-induced conversion of analytes to hyperluminescent derivatives thus offers a more sensitive approach than UV fluorescence for detecting extremely small quantities of material. Mixtures of the hydroxyindoles serotonin (5-hydroxytryptamine), 5-hydroxytryptophan, and 5-hydroxyindole acetic acid are reliably characterized (relative error approximately 10%) in 100 s, with detection limits as low as approximately 70 zmol (approximately 42,000 molecules). The sensitivity of this measurement strategy improves on the best previously reported results for capillary separations of indoles by more than one order of magnitude.
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Affiliation(s)
- M L Gostkowski
- Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, USA
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