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Abstract
Steady-state measurements of fluorescence polarization have been widely adopted in the field of high-throughput screening for the study of biomolecular interactions. This chapter reviews the basic theory of fluorescence polarization, the underlying principle for using fluorescence polarization to study interactions between small-molecule fluorophores and macromolecular targets, and representative applications of fluorescence polarization in high-throughput screening.
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Affiliation(s)
- Xinyi Huang
- Immunology, Inflammation and Infectious Diseases Discovery and Translational Area Roche Pharma Research & Early Development, Roche Innovation Center Shanghai, Roche R&D Center (China) Ltd, 720 Cai Lun Road, Bldg 5, Pudong, Shanghai, 201203, China.
| | - Ann Aulabaugh
- Immunology, Inflammation and Infectious Diseases Discovery and Translational Area Roche Pharma Research & Early Development, Roche Innovation Center Shanghai, Roche R&D Center (China) Ltd, 720 Cai Lun Road, Bldg 5, Pudong, Shanghai, 201203, China
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Lo KKW. Luminescent Iridium(III) and Rhenium(I) Complexes as Biomolecular Probes and Imaging Reagents. ADVANCES IN INORGANIC CHEMISTRY 2016. [DOI: 10.1016/bs.adioch.2015.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Lo KKW. Luminescent Rhenium(I) and Iridium(III) Polypyridine Complexes as Biological Probes, Imaging Reagents, and Photocytotoxic Agents. Acc Chem Res 2015; 48:2985-95. [PMID: 26161527 DOI: 10.1021/acs.accounts.5b00211] [Citation(s) in RCA: 391] [Impact Index Per Article: 43.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although the interactions of transition metal complexes with biological molecules have been extensively studied, the use of luminescent transition metal complexes as intracellular sensors and bioimaging reagents has not been a focus of research until recently. The main advantages of luminescent transition metal complexes are their high photostability, long-lived phosphorescence that allows time-resolved detection, and large Stokes shifts that can minimize the possible self-quenching effect. Also, by the use of transition metal complexes, the degree of cellular uptake can be readily determined using inductively coupled plasma mass spectrometry. For more than a decade, we have been interested in the development of luminescent transition metal complexes as covalent labels and noncovalent probes for biological molecules. We argue that many transition metal polypyridine complexes display triplet charge transfer ((3)CT) emission that is highly sensitive to the local environment of the complexes. Hence, the biological labeling and binding interactions can be readily reflected by changes in the photophysical properties of the complexes. In this laboratory, we have modified luminescent tricarbonylrhenium(I) and bis-cyclometalated iridium(III) polypyridine complexes of general formula [Re(bpy-R(1))(CO)3(py-R(2))](+) and [Ir(ppy-R(3))2(bpy-R(4))](+), respectively, with reactive functional groups and used them to label the amine and sulfhydryl groups of biomolecules such as oligonucleotides, amino acids, peptides, and proteins. Additionally, using a range of biological substrates such as biotin, estradiol, and indole, we have designed luminescent rhenium(I) and iridium(III) polypyridine complexes as noncovalent probes for biological receptors. The interesting results generated from these studies have prompted us to investigate the possible applications of luminescent transition metal complexes in intracellular systems. Thus, in the past few years, we have developed an interest in the cytotoxic activity, cellular uptake, and bioimaging applications of these complexes. Additionally, we and other research groups have demonstrated that many transition metal complexes have facile cellular uptake and organelle-localization properties and that their cytotoxic activity can be readily controlled. For example, complexes that can target the nucleus, nucleolus, mitochondria, lysosomes, endoplasmic reticulum, and Golgi apparatus have been identified. We anticipate that this selective localization property can be utilized in the development of intracellular sensors and bioimaging reagents. Thus, we have functionalized luminescent rhenium(I) and iridium(III) polypyridine complexes with various pendants, including molecule-binding moieties, sugar molecules, bioorthogonal functional groups, and polymeric chains such as poly(ethylene glycol) and polyethylenimine, and examined their potentials as biological reagents. This Account describes our design of luminescent rhenium(I) and iridium(III) polypyridine complexes and explains how they can serve as a new generation of biological reagents for diagnostic and therapeutic applications.
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Affiliation(s)
- Kenneth Kam-Wing Lo
- Department of Biology and
Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P. R. China
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Lo KKW, Li SPY. Utilization of the photophysical and photochemical properties of phosphorescent transition metal complexes in the development of photofunctional cellular sensors, imaging reagents, and cytotoxic agents. RSC Adv 2014. [DOI: 10.1039/c3ra47611a] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Lo KKW, Hui WK, Chung CK, Tsang KHK, Lee TKM, Ng DCM. Luminescent Transition Metal Polypyridine Biotin Complexes. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.200600007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Zou M, Li Y, Wang J, Wang Q, Kong Y, Gao J, Fan P. Spectroscopic Investigation on Sonocatalytic Damage of BSA Molecules by FeIII Complexes with Binary Organic Acid Ligands Under Ultrasonic Irradiation. J SOLUTION CHEM 2013. [DOI: 10.1007/s10953-013-9996-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Geiss BJ, Stahla-Beek HJ, Hannah AM, Gari HH, Henderson BR, Saeedi BJ, Keenan SM. A high-throughput screening assay for the identification of flavivirus NS5 capping enzyme GTP-binding inhibitors: implications for antiviral drug development. ACTA ACUST UNITED AC 2011; 16:852-61. [PMID: 21788392 DOI: 10.1177/1087057111412183] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There are no effective antivirals currently available for the treatment of flavivirus infection in humans. As such, the identification and characterization of novel drug target sites are critical to developing new classes of antiviral drugs. The flavivirus NS5 N-terminal capping enzyme (CE) is vital for the formation of the viral RNA cap structure, which directs viral polyprotein translation and stabilizes the 5' end of the viral genome. The structure of the flavivirus CE has been solved, and a detailed understanding of the CE-guanosine triphosphate (GTP) and CE-RNA cap interactions is available. Because of the essential nature of the interaction for viral replication, disrupting CE-GTP binding is an attractive approach for drug development. The authors have previously developed a robust assay for monitoring CE-GTP binding in real time. They adapted this assay for high-throughput screening and performed a pilot screen of 46 323 commercially available compounds. A number of small-molecule inhibitors capable of displacing a fluorescently labeled GTP in vitro were identified, and a second functional assay was developed to identify false positives. The results presented indicate that the flavivirus CE cap-binding site is a valuable new target site for antiviral drug discovery and should be further exploited for broad-spectrum anti-flaviviral drug development.
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Affiliation(s)
- Brian J Geiss
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
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Lo KKW, Li SPY, Zhang KY. Development of luminescent iridium(iii) polypyridine complexes as chemical and biological probes. NEW J CHEM 2011. [DOI: 10.1039/c0nj00478b] [Citation(s) in RCA: 195] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Dynamics of tRNAtyr Probed with Long-Lifetime Metal-Ligand Complexes. J Fluoresc 2011; 21:231-7. [DOI: 10.1007/s10895-010-0710-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 08/12/2010] [Indexed: 11/27/2022]
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Kim MS, Kim JH, Son BW, Kang JS. Dynamics of bacteriophage R17 probed with a long-lifetime Ru(II) metal-ligand complex. J Fluoresc 2010; 20:713-8. [PMID: 20195712 DOI: 10.1007/s10895-010-0612-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 02/07/2010] [Indexed: 10/19/2022]
Abstract
The metal-ligand complex, [Ru(2,2'-bipyridine)(2)(4,4'-dicarboxy-2,2'-bipyridine)](2+) (RuBDc), was used as a spectroscopic probe for studying macromolecular dynamics. RuBDc is a very photostable probe that possesses favorable photophysical properties including long lifetime, high quantum yield, large Stokes' shift, and highly polarized emission. To further show the usefulness of this luminophore for probing macromolecular dynamics, we examined the intensity and anisotropy decays of RuBDc when conjugated to R17 bacteriophage using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The intensity decays were best fit by a sum of two exponentials, and we obtained a longer mean lifetime at 4 degrees C (<tau> = 491.8 ns) as compared to that at 25 degrees C (<tau> = 435.1 ns). The anisotropy decay data showed a single rotational correlation time, which is typical for a spherical molecule, and the results showed a longer rotational correlation time at 4 degrees C (2,574.9 ns) than at 25 degrees C (2,070.1 ns). The use of RuBDc enabled us to measure the rotational correlation time up to several microseconds. These results indicate that RuBDc has significant potential for studying hydrodynamics of biological macromolecules.
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Affiliation(s)
- Myung Sup Kim
- Department of Oral Biochemistry and Molecular Biology, School of Dentistry, Pusan National University, Yangsan 626-870, Korea
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Zhang KY, Li SPY, Zhu N, Or IWS, Cheung MSH, Lam YW, Lo KKW. Structure, Photophysical and Electrochemical Properties, Biomolecular Interactions, and Intracellular Uptake of Luminescent Cyclometalated Iridium(III) Dipyridoquinoxaline Complexes. Inorg Chem 2010; 49:2530-40. [DOI: 10.1021/ic902465b] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kenneth Yin Zhang
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Steve Po-Yam Li
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Nianyong Zhu
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
| | - Iyana Wai-Shan Or
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Maggie Shau-Ha Cheung
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Yun-Wah Lam
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Kenneth Kam-Wing Lo
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
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Lo KKW. Exploitation of Luminescent Organometallic Rhenium(I) and Iridium(III) Complexes in Biological Studies. TOP ORGANOMETAL CHEM 2010. [DOI: 10.1007/3418_2009_3] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Wang J, Wang Y, Gao J, Hu P, Guan H, Zhang L, Xu R, Chen X, Zhang X. Investigation on damage of BSA molecules under irradiation of low frequency ultrasound in the presence of FeIII-tartrate complexes. ULTRASONICS SONOCHEMISTRY 2009; 16:41-49. [PMID: 18706848 DOI: 10.1016/j.ultsonch.2008.07.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 06/19/2008] [Accepted: 07/08/2008] [Indexed: 05/26/2023]
Abstract
The interaction between bovine serum albumin (BSA) and Fe(III)-tartrate complexes ([Fe(III)(tar)(H(2)O)(3)](-) and [Fe(III)(tar)(2)](5-)) as well as the damage of BSA in the presence of Fe(III)-tartrate complexes under ultrasonic irradiation was studied by UV-vis and fluorescence spectra. In addition, the influences of ultrasonic irradiation time, Fe(III)-tartrate complex concentration, ionic strength and solution acidity (pH value) were also examined on the damage of BSA. The results showed that the fluorescence quenching of BSA caused by the Fe(III)-tartrate complexes belonged to the static quenching. The BSA and Fe(III)-tartrate complexes interacted with each other mainly through weak interaction and coordinate actions. The corresponding binding association constants (K) and the binding site numbers (n) were calculated. The results were as follows: K(1)=1.67 x 10(3) L mol(-1) and n(1)=0.9699 for [Fe(III)(tar)(H(2)O)(3)](-), K(2)=1.54 x 10(3) L mol(-1) and n(2)=0.8754 for [Fe(III)(tar)(2)](5-). Otherwise, under ultrasonic irradiation the BSA molecules were obviously damaged by the Fe(III)-tartrate complexes. The damage degree rose up with the increase of ultrasonic irradiation time, Fe(III)-tartrate complex concentration, pH value and ionic strength. And that, [Fe(III)(tar)(H(2)O)(3)](-) exhibited higher sonocatalytic activity in a way than [Fe(III)(tar)(2)](5-).
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Affiliation(s)
- Jun Wang
- Department of Chemistry, Liaoning University, Shenyang 110036, People's Republic of China.
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Abstract
Steady-state measurements of fluorescence polarization have been widely adopted in the field of high-throughput screening for the study of biomolecular interactions. This chapter reviews the basic theory of fluorescence polarization, the underlying principle for using fluorescence polarization to study interactions between small-molecule fluorophores and macromolecular targets, and representative applications of fluorescence polarization in high-throughput screening.
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Affiliation(s)
- Xinyi Huang
- Chemical and Screening Sciences, Wyeth Research, Collegeville, PA, USA
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Hemmilá I, Mukkala VM. Time-Resolution in Fluorometry Technologies, Labels, and Applications in Bioanalytical Assays. Crit Rev Clin Lab Sci 2008. [DOI: 10.1080/20014091084254] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Jiménez-Hernández ME, Orellana G, Montero F, Portolés MT. A Ruthenium Probe for Cell Viability Measurement Using Flow Cytometry, Confocal Microscopy and Time-resolved Luminescence ¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2000)0720028arpfcv2.0.co2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Lo KKW, Hui WK, Chung CK, Tsang KHK, Lee TKM, Li CK, Lau JSY, Ng DCM. Luminescent transition metal complex biotin conjugates. Coord Chem Rev 2006. [DOI: 10.1016/j.ccr.2006.01.010] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Lo KKW. Luminescent Transition Metal Complexes as Biological Labels and Probes. PHOTOFUNCTIONAL TRANSITION METAL COMPLEXES 2006. [DOI: 10.1007/430_2006_040] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Investigation of the monomeric and oligomeric molecular forms of human growth hormone and poly-L-lysine using fluorescence anisotropy measurement method. Polym Bull (Berl) 2005. [DOI: 10.1007/s00289-005-0474-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
Transforming growth factor-beta is a pleiotropic growth factor that has enthralled many investigators for approximately two decades. In addition to many reports that have clarified the basic mechanism of transforming growth factor-beta signal transduction, numerous laboratories have published on the clinical implication/application of transforming growth factor-beta . To name a few, dysregulation of transforming growth factor-beta signaling plays a role in carcinogenesis, autoimmunity, angiogenesis, and wound healing. In this report, we will review these clinical implications of transforming growth factor-beta .
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Affiliation(s)
- Isaac Yi Kim
- Department of Urology, University of California at Irvine, Orange, CA 92868, USA
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Lo KKW, Hui WK, Chung CK, Tsang KHK, Ng DCM, Zhu N, Cheung KK. Biological labelling reagents and probes derived from luminescent transition metal polypyridine complexes. Coord Chem Rev 2005. [DOI: 10.1016/j.ccr.2004.10.004] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Herman P, Malinsky J, Plasek J, Vecer J. Pseudo real-time method for monitoring of the limiting anisotropy in membranes. J Fluoresc 2005; 14:79-85. [PMID: 15622865 DOI: 10.1023/b:jofl.0000014664.60479.f2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Data acquisition and analysis of the time-resolved fluorescence anisotropy is typically a time consuming process preventing usage of this experimental method for monitoring of time-dependent phenomena. We describe a method for pseudo real-time monitoring of the limiting fluorescence anisotropy r(infinity) allowing to track changes of the membrane order occurring on the time scale of minutes. Principle and performance of the method is demonstrated in the time domain with the time-correlated single photon counting detection. DMPC liposomes stained with 1,6-diphenyl-1,3,5-hexatriene (DPH) have been used to test influence of the diffusion membrane potential on the membrane order during the temperature-induced phase transition in DMPC membranes. It has been found that the transmembrane field of the order of -70 mV increases the phase transition temperature by about 1.5 degrees C-2 degrees C. It is proposed that the full advantage of the method can be utilized with a gated detection, which besides a faster data acquisition brings additional advantage of excitation light suppression. The method can be also used for imaging.
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Affiliation(s)
- P Herman
- Institute of Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic.
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Kang JS, Son BW, Choi HD, Yoon JH, Son WS. Dynamics of Supercoiled and Linear pBluescript II SK(+) Phagemids Probed with a Long-lifetime Metal-ligand Complex. BMB Rep 2005; 38:104-10. [PMID: 15715954 DOI: 10.5483/bmbrep.2005.38.1.104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We extended the measurable time scale of DNA dynamics to microsecond using [Ru(phen)(2)(dppz)](2+)(phen = 1,10-phenanthroline, dppz=dipyrido[3,2-a:2',3'-c]phenazine)(RuPD) , which displays a mean lifetime near 500 ns. To evaluate the usefulness of this luminophore (RuPD) for probing nucleic acid dynamics, its intensity and anisotropy decays when intercalated into supercoiled and linear pBluescript (pBS) II SK(+) phagemids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetime for the supercoiled phagemids (<tau> = 489.7 ns) was somewhat shorter than that for the linear phagemids (<tau> = 506.4 ns), suggesting a more efficient shielding from water by the linear phagemids. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled phagemids (997.2 ns) than for the linear phagemids (1175.6 ns). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the phagemids, respectively. These results indicate that RuPD can have applications in studies of both bending and torsional dynamics of nucleic acids.
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Affiliation(s)
- Jung Sook Kang
- Department of Oral Biochemistry and Molecular Biology, College of Dentistry, Pusan National University, Busan 602-739, Korea.
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Guo LH, Yang XQ. A new chemically amplified electrochemical system for the detection of biological affinity reactions: direct and competitive biotin assay. Analyst 2005; 130:1027-31. [PMID: 15965525 DOI: 10.1039/b413089h] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Quantitation of biological affinity reactions by a newly developed chemically amplified electrochemical detection method was demonstrated with the biotin-avidin binding pair. In the method, ruthenium tris(2,2'-bipyridine)(Ru-bipy) was used as an electrochemical signal-generating tag. Its oxidation current on an indium tin oxide (ITO) electrode was amplified with a sacrificial electron donor, oxalate. Because oxalate itself produced negligible current on the electrode, the signal-to-background ratio was greatly enhanced in comparison with other chemical amplification systems. Although the Ru-bipy/oxalate redox couple has been employed previously in electrochemiluminescent and photoelectrochemical detection, its use in a catalytic amperometric detection of biological binding assays has not been reported. To implement the method in the detection of biotin-avidin recognition, avidin was immobilized on an ITO electrode, and was reacted with biotin in solution. Immobilization of avidin by passive adsorption was found to be relatively stable under the condition of the affinity reaction. In the direct assay, biotin labelled with Ru-bipy was recognized by avidin and accumulated on the electrode surface, which was then detected electrochemically in the presence of oxalate. A linear relationship between electrochemical current and biotin concentration was obtained in the range of 1-300 ng mL(-1). In the competitive assay, a mixed solution of unlabelled biotin (the analyte) of various concentrations and 100 ng mL(-1) labelled biotin was reacted with avidin on the surface. As the concentration of the unlabelled biotin increased, less labelled biotin bound to avidin, leading to a reduction in the electro-catalytical response of Ru-bipy. A detection limit of 1 ng mL(-1) biotin was obtained in the competitive assay, which is close to the sensitivity of some enzyme-labelled amperometric assays.
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Affiliation(s)
- Liang-Hong Guo
- State Key Laboratory of Environmental Chemistry and Eco-toxicology, Research Centre for Eco-environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China.
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Zheng D, Wang N, Wang FQ, Dong D, Li YG, Yang XQ, Guo LH, Cheng J. Sensitive chemically amplified electrochemical detection of ruthenium tris-(2,2′-bipyridine) on tin-doped indium oxide electrode. Anal Chim Acta 2004. [DOI: 10.1016/j.aca.2003.12.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Dong D, Zheng D, Wang FQ, Yang XQ, Wang N, Li YG, Guo LH, Cheng J. Quantitative Photoelectrochemical Detection of Biological Affinity Reaction: Biotin−Avidin Interaction. Anal Chem 2003; 76:499-501. [PMID: 14719905 DOI: 10.1021/ac035184p] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Quantitative detection of a biological affinity reaction, the biotin/avidin recognition, was achieved using our newly developed photoelectrochemical analytical system. The system is based on the operation mechanism of the well-developed dye-sensitized photoelectrochemical solar cells and comprises a ruthenium tris(2,2'-bipyridine) (Ru-bipy) derivative as the photoelectrochemical signal-generating molecule, oxalate as the sacrificial electron donor, and tin oxide nanoparticle as the semiconductor electrode material. To perform the affinity reaction, avidin was immobilized on SnO(2) electrode by passive adsorption. Biotin-linked bovine serum albumin (BSA) was labeled with an NHS-ester derivative of Ru-bipy. After binding of BSA to the surface-immobilized avidin through biotin, photoelectrochemical measurement was carried out in the presence of oxalate. Anodic photocurrent was turned on and off repeatedly by control of incidental light. The action spectrum of the photocurrent resembled the absorption spectrum of Ru-bipy, proving the photocurrent was generated from the metal complex. A linear relationship between photocurrent and BSA concentration was obtained in the range of 1-100 microg/mL. This is the first case of quantitative photoelectrochemical detection of a biological affinity interaction.
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Huang X. Fluorescence polarization competition assay: the range of resolvable inhibitor potency is limited by the affinity of the fluorescent ligand. JOURNAL OF BIOMOLECULAR SCREENING 2003; 8:34-8. [PMID: 12854996 DOI: 10.1177/1087057102239666] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
For the development of fluorescence polarization (FP) competition assays, there is a widespread belief that tight-binding fluorescent ligands should be avoided to identify inhibitors of low or intermediate potency in the screening of small-molecule compound libraries. It is demonstrated herein that this statement is a misconception; in fact, the higher the affinity of the fluorescent ligand, the wider the range of inhibitor potency that can be resolved. An approximate estimate for the low end of inhibitor K(i) values that can be resolved is the K(d) value of the fluorescent ligand. Because FP competition assays are typically conducted under nonstoichiometric titration conditions, it is suggested that a fluorescent ligand of highest affinity that also has an adequate quantum yield to satisfy such conditions be selected.
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Affiliation(s)
- Xinyi Huang
- Wyeth Research, Division of Biological Chemistry, Pearl River, NY 10965, USA.
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Roy BC, Chandra B, Hromas D, Mallik S. Synthesis of new, pyrene-containing, metal-chelating lipids and sensing of cupric ions. Org Lett 2003; 5:11-4. [PMID: 12509878 DOI: 10.1021/ol026891s] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The syntheses of several saturated, pyrene-containing, metal-chelating lipids are described. These lipids are capable of strongly binding to transition metal ions employing the metal-chelating headgroup. The excimer-to-monomer ratio of the pyrene groups changes with addition of cupric ions to the liposomes. Three other transition metal ions (Zn(2+), Ni(2+), and Hg(2+)) did not cause any appreciable changes in the excimer-to-monomer ratio. [reaction--see text]
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Affiliation(s)
- Bidhan C Roy
- Department of Chemistry, North Dakota State University, Fargo, ND 58105, USA
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Herman P, Maliwal BP, Lakowicz JR. Real-time background suppression during frequency domain lifetime measurements. Anal Biochem 2002; 309:19-26. [PMID: 12381357 PMCID: PMC6945983 DOI: 10.1016/s0003-2697(02)00213-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We describe real time background suppression of autofluorescence from biological samples during frequency domain or phase modulation measurements of intensity decays. For these measurements the samples were excited with a train of light pulses with widths below 1 ps. The detector was gated off for a short time period of 10 to 40 ns during and shortly after the excitation pulse. The reference signal needed for the frequency domain measurement was provided by a long-lifetime reference fluorophore which continues to emit following the off-gating pulse. Both the sample and the reference were measured under identical optical and electronic conditions avoiding the need for correction of the photomultiplier tube signal for the gating sequence. We demonstrate frequency domain background suppression using a mixture of short- and long-lifetime probes and for a long-lifetime probe in human plasma with significant autofluorescence.
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Andreev OA, Reshetnyak YK, Goldfarb RH. Evidence of inter- and intra-molecular crosslinking of tyrosine residues of calmodulin induced by photo-activation of ruthenium(II). Photochem Photobiol Sci 2002; 1:834-6. [PMID: 12656487 DOI: 10.1039/b201474b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tris(2,2'-bipyridyl)ruthenium(n) upon illumination with light at a wavelength of 450 nm in the presence of an electron acceptor induces dityrosine crosslinking in proteins.
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Affiliation(s)
- Oleg A Andreev
- Department of Molecular Biology and Immunology, Institute for Cancer Research, University of North Texas Health Science Center at Fort Worth, 3500 Camp Bowie Blvd, Fort Worth, TX 7610, USA.
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31
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Kang JS, Abugo OO, Lakowicz JR. Dynamics of supercoiled and relaxed pTZ18U plasmids probed with a long-lifetime metal-ligand complex. JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2002; 35:389-94. [PMID: 12296998 PMCID: PMC6880806 DOI: 10.5483/bmbrep.2002.35.4.389] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
[Ru(bpy)2(dppz)](2+) (bpy = 2,2'-bipyridine, dppz = dipyrido- [3,2-a:2',3'-c]phenazine) (RuBD), a long-lifetime metalligand complex, displays favorable photophysical properties. These include long lifetime, polarized emission, but no significant fluorescence from the complex that is not bound to DNA. To show the usefulness of this luminophore (RuBD) for probing the bending and torsional dynamics of nucleic acids, its intensity and anisotropy decays when intercalated into supercoiled and relaxed pTZ18U plasmids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetimes for the supercoiled plasmids (< tau > = 148 ns) were somewhat shorter than those for the relaxed plasmids (< tau > = 160 ns). This suggests that the relaxed plasmids were shielded more efficiently from water. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled plasmids (288 ns) than for the relaxed plasmids (355 ns). The presence of two rotational correlation times suggests that RuBD reveals both the bending and torsional motions of the plasmids. These results indicate that RuBD can be useful for studying both the bending and torsional dynamics of nucleic acids.
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Affiliation(s)
- Jung Sook Kang
- Department of Oral Biochemistry and Molecular Biology, College of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Pusan 602-739, Korea.
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Kang JS, Abugo OO, Lakowicz JR. Dynamics of supercoiled and linear pTZ18U plasmids observed with a long-lifetime metal-ligand complex. Biopolymers 2002; 67:121-8. [PMID: 12073934 DOI: 10.1002/bip.10057] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The metal-ligand complex, [Ru(bpy)2(dppz)]2+ (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine) (Ru-BD), was used as a spectroscopic probe for studying nucleic acid dynamics. The Ru-BD complex displays a long lifetime of over 100 ns and a molecular light switch property upon DNA binding due to shielding of its dppz ligand from water. To further show the usefulness of this luminophore (Ru-BD) for probing DNA dynamics, we examined its intensity and anisotropy decays when intercalated into supercoiled and linear pTZ18U plasmids using frequency-domain fluorometry with a light-emitting diode (LED) as the modulated light source. Compared to the supercoiled plasmids with an average intensity decay time of 120.8 ns at 25 degrees C, we obtained somewhat longer lifetimes for the linear plasmids ((tau) = 141.4 ns at 25 degrees C), suggesting a more efficient shielding from water by the linear plasmids. The anisotropy decay data also showed longer rotational correlation times for the linear plasmids (495 and 35 ns at 25 degrees C) as compared to the supercoiled plasmids (412 and 27 ns at 25 degrees C). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the plasmids, respectively. The anisotropy values were quite similar, although the values of the supercoiled plasmids were slightly higher in both the steady-state and anisotropy decay measurements. These results indicate that Ru-BD can be applied in the study of both bending and torsional dynamics of nucleic acids.
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Affiliation(s)
- Jung Sook Kang
- Department of Oral Biochemistry and Molecular Biology, College of Dentistry, Pusan National University, Korea
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Kang JS, Piszczek G, Lakowicz JR. High-molecular-weight protein hydrodynamics studied with a long-lifetime metal-ligand complex. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1597:221-8. [PMID: 12044900 PMCID: PMC6800114 DOI: 10.1016/s0167-4838(02)00281-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[Ru(2,2'-bipyridine)(2)(4,4'-dicarboxy-2,2'-bipyridine)](2+) (RuBDc) is a very photostable probe that possesses favorable photophysical properties including long lifetime, high quantum yield, large Stokes' shift, and highly polarized emission. In the present study, we demonstrated the usefulness of this probe for monitoring the rotational diffusion of high-molecular-weight (MW) proteins. Using frequency-domain fluorometry with a high-intensity, blue light-emitting diode (LED) as the modulated light source, we compared the intensity and anisotropy decays of RuBDc conjugated to immunoglobulin G (IgG) and immunoglobulin M (IgM), which show a six-fold difference in MW We obtained slightly longer lifetimes for IgM (=428 ns in buffer) than IgG (=422 ns in buffer) in the absence and presence of glycerol, suggesting somewhat more efficient shielding of RuBDc from water in IgM than in IgG. The anisotropy decay data showed longer rotational correlation times for IgM (1623 and 65.7 ns in buffer) as compared to IgG (264 and 42.5 ns in buffer). Importantly, the ratio of the long rotational correlation times of IgM to IgG in buffer was 6.2, which is very close to that of MW of IgM to IgG (6.0). The shorter correlation times are most likely to be associated with domain motions within the proteins. The anisotropy decays reflect both the molecular size and shape of the immunoglobulins, as well as the viscosity. These results show that RuBDc can have numerous applications in studies of high-MW protein hydrodynamics and in fluorescence polarization immunoassays (FPI) of high-MW analytes.
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Affiliation(s)
- Jung Sook Kang
- Department of Biochemistry and Molecular Biology, Center for Fluorescence Spectroscopy, University of Maryland at Baltimore, 725 West Lombard Street, Baltimore, MD 21201, USA
- Department of Oral Biochemistry and Molecular Biology, College of Dentistry, Pusan National University, Pusan 602-739, South Korea
| | - Grzegorz Piszczek
- Department of Biochemistry and Molecular Biology, Center for Fluorescence Spectroscopy, University of Maryland at Baltimore, 725 West Lombard Street, Baltimore, MD 21201, USA
- Institute of Experimental Physics, University of Gdańsk, ul. Wita Stwosza 57, 80-952 Gdańsk, Poland
| | - Joseph R. Lakowicz
- Department of Biochemistry and Molecular Biology, Center for Fluorescence Spectroscopy, University of Maryland at Baltimore, 725 West Lombard Street, Baltimore, MD 21201, USA
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Kang JS, Lakowicz JR, Piszczek G. DNA dynamics: a fluorescence resonance energy transfer study using a long-lifetime metal-ligand complex. Arch Pharm Res 2002; 25:143-50. [PMID: 12009026 PMCID: PMC6904224 DOI: 10.1007/bf02976554] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Fluorescent probes bound to DNA typically display nanosecond decay times and reveal only nanosecond motions. We extend the time range of measurable DNA dynamics using [Ru(bpy)2(dppz)]2+ (bpy=2,2'-bipyridine, dppz=dipyrido[3,2-a:2',3'-c]phenazine) (RuBD) which displays a mean lifetime near 90 ns. To test the usefulness of RuBD as a probe for diffusive processes in calf thymus DNA, we compared the efficiencies of fluorescence resonance energy transfer (FRET) using three donors which display lifetimes near 5 ns for acridine orange (AO), 22 ns for ethidium bromide (EB) and 92 ns for RuBD, with nile blue (NB) as the acceptor. The Forster distances for AO-NB, EB-NB and RuBD-NB donor-acceptor pairs were 42.3, 52.3, and 30.6 A, respectively. All three donors showed dramatic decreases in fluorescence intensities and more rapid intensity decays with increasing NB concentrations. The intensity decays of AO and EB in the presence of varying concentrations of NB were satisfactorily described by the one-dimensional FRET model without diffusion (Blumen and Manz, 1979). In the case of the long-lifetime donor RuBD, the experimental phase and modulation somewhat deviated from the recovered values computed from this model. The recovered NB concentrations and FRET efficiencies from the model were slightly larger than the expected values, however, the recovered and expected values did not show a significant difference. Thus, it is suggested that the lifetime of RuBD is too short to measure diffusive processes in calf thymus DNA.
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Affiliation(s)
- Jung Sook Kang
- Department of Oral Biochemistry and Molecular Biology, College of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, Korea.
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35
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36
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Kakehi K, Oda Y, Kinoshita M. Fluorescence polarization: analysis of carbohydrate-protein interaction. Anal Biochem 2001; 297:111-6. [PMID: 11673876 DOI: 10.1006/abio.2001.5309] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fluorescence polarization has been widely used for the studies on the molecular motion in solution and has been applied to immunoassays for proteins, therapeutic drug monitoring in clinical pharmacy, and assays for environmentally toxic compounds. Because fluorescence polarization is most readily applicable to the kinetic analysis of the binding reaction between a substance having small molecular mass and a receptor molecule, this method is easily applied to the analysis of carbohydrate-lectin binding. In this tutorial Thematic Review, we briefly introduce the principles of fluorescence polarization and some applications of fluorescence polarization technique to glycobiology.
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Affiliation(s)
- K Kakehi
- Faculty of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka, 577, Japan.
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37
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Kinoshita M, Okino A, Oda Y, Kakehi K. Anomalous migration of hyaluronic acid oligomers in capillary electrophoresis: correlation to susceptibility to hyaluronidase. Electrophoresis 2001; 22:3458-65. [PMID: 11669526 DOI: 10.1002/1522-2683(200109)22:16<3458::aid-elps3458>3.0.co;2-0] [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: 11/07/2022]
Abstract
During high-resolution capillary electrophoresis analysis in an electrolyte solution containing a neutral polymer, small oligomers of regularly arranged acidic polysaccharides such as hyaluronic acid and N-acetylneuraminic acid polymers showed reversal of the migration order. This anomalous migration was well correlated with their reported biological activity. In the present study, we analyzed hyaluronidase action on the purified hyaluronic acid oligomers using capillary electrophoresis and found that hydrolytic and transglycosylation actions by hyaluronidase were dependent on the molecular sizes of hyaluronic acid oligomers, and well correlated to their migration profiles. Furthermore, fluorescent polarization technique was employed for understanding the relationship between molecular size of hyaluronic acid oligomers and their electromigrations.
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Affiliation(s)
- M Kinoshita
- Faculty of Pharmaceutical Sciences, Kinki University, Higashi-osaka, Japan
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38
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Martin SE, Maggie Connatser R, Kane-Maguire NA, Wheeler JF. Capillary electrophoresis with laser-induced fluorescence detection for chiral analysis and DNA binding studies of ruthenium(II) Tris–diimine complexes. Anal Chim Acta 2001. [DOI: 10.1016/s0003-2670(01)01248-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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39
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Guerrero J, Piro OE, Wolcan E, Feliz MR, Ferraudi G, Moya SA. Photochemical and Photophysical Reactions of fac-Rhenium(I) Tricarbonyl Complexes. Effects from Binucleating Spectator Ligands on Excited and Ground State Processes. Organometallics 2001. [DOI: 10.1021/om000784p] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. Guerrero
- INIFTA(CONICET), Universidad Nacional de La Plata, C.C. 16, Suc. 4, 1900 La Plata, Argentina, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556-0579, Department of Applied Chemistry, Facultad de Química y Biología, Universidad de Santiago, Casilla 40, Correo 33, Santiago, Chile, and Department of Physics, Facultad de Ciencias Exactas, Universidad Nacional de La Plata and PROFIMO(CONICET), C.C. 67, 1900 La Plata, Argentina
| | - O. E. Piro
- INIFTA(CONICET), Universidad Nacional de La Plata, C.C. 16, Suc. 4, 1900 La Plata, Argentina, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556-0579, Department of Applied Chemistry, Facultad de Química y Biología, Universidad de Santiago, Casilla 40, Correo 33, Santiago, Chile, and Department of Physics, Facultad de Ciencias Exactas, Universidad Nacional de La Plata and PROFIMO(CONICET), C.C. 67, 1900 La Plata, Argentina
| | - E. Wolcan
- INIFTA(CONICET), Universidad Nacional de La Plata, C.C. 16, Suc. 4, 1900 La Plata, Argentina, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556-0579, Department of Applied Chemistry, Facultad de Química y Biología, Universidad de Santiago, Casilla 40, Correo 33, Santiago, Chile, and Department of Physics, Facultad de Ciencias Exactas, Universidad Nacional de La Plata and PROFIMO(CONICET), C.C. 67, 1900 La Plata, Argentina
| | - M. R. Feliz
- INIFTA(CONICET), Universidad Nacional de La Plata, C.C. 16, Suc. 4, 1900 La Plata, Argentina, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556-0579, Department of Applied Chemistry, Facultad de Química y Biología, Universidad de Santiago, Casilla 40, Correo 33, Santiago, Chile, and Department of Physics, Facultad de Ciencias Exactas, Universidad Nacional de La Plata and PROFIMO(CONICET), C.C. 67, 1900 La Plata, Argentina
| | - G. Ferraudi
- INIFTA(CONICET), Universidad Nacional de La Plata, C.C. 16, Suc. 4, 1900 La Plata, Argentina, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556-0579, Department of Applied Chemistry, Facultad de Química y Biología, Universidad de Santiago, Casilla 40, Correo 33, Santiago, Chile, and Department of Physics, Facultad de Ciencias Exactas, Universidad Nacional de La Plata and PROFIMO(CONICET), C.C. 67, 1900 La Plata, Argentina
| | - S. A. Moya
- INIFTA(CONICET), Universidad Nacional de La Plata, C.C. 16, Suc. 4, 1900 La Plata, Argentina, Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556-0579, Department of Applied Chemistry, Facultad de Química y Biología, Universidad de Santiago, Casilla 40, Correo 33, Santiago, Chile, and Department of Physics, Facultad de Ciencias Exactas, Universidad Nacional de La Plata and PROFIMO(CONICET), C.C. 67, 1900 La Plata, Argentina
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40
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Kane-Maguire NA, Wheeler JF. Photoredox behavior and chiral discrimination of DNA bound M(diimine)3n+ complexes (M=Ru2+, Cr3+). Coord Chem Rev 2001. [DOI: 10.1016/s0010-8545(00)00280-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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41
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Jiménez-Hernández ME, Orellana G, Montero F, Portolés MT. A ruthenium probe for cell viability measurement using flow cytometry, confocal microscopy and time-resolved luminescence. Photochem Photobiol 2000; 72:28-34. [PMID: 10911726 DOI: 10.1562/0031-8655(2000)072<0028:arpfcv>2.0.co;2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The capability of the new luminescent probe (dibenzo[h,j] dipyrido[3,2-a:2',3'-c]phenazine)bis(2,2'-bipyridine)ruthenium(II) dication, (RB2Z), to discriminate live and dead cells has been tested on rat hepatocytes and mouse lymphocytes. RB2Z-stained cells were analyzed using flow cytometry, fluorescence (confocal) microscopy and time-resolved luminescence measurements. The established viability probes propidium iodide (PI) and SYTOX green (SG) were used as controls. The intense luminescence of RB2Z at 606 nm is localized in the nucleus of nonviable cells. Viability measurements by flow cytometry and fluorescence microscopy using RB2Z as dead-cell marker yield the same results as PI and SG. The luminescence lifetime of RB2Z also displays sensitivity to cell viability (0.45 and 0.82 microsecond in presence of fully viable and dead cells, respectively). This ruthenium complex is photostable under laser sources and its 200 nm Stokes shift facilitates multicolor labeling experiments in flow cytometry and fluorescence microscopy. Unlike the currently available probes, the long-lived excited state of RB2Z also allows assays based on luminescence decay measurements.
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Affiliation(s)
- M E Jiménez-Hernández
- Department of Organic Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, Spain
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42
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Lakowicz JR, Gryczynski I, Gryczynski Z, Johnson ML. Background suppression in frequency-domain fluorometry. Anal Biochem 2000; 277:74-85. [PMID: 10610691 PMCID: PMC6911226 DOI: 10.1006/abio.1999.4346] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gated detection is often used in time-domain measurements of long-lived fluorophores for suppression of interfering short-lived autofluorescence. However, no direct method has been available for gated detection and background suppression when using frequency-domain fluorometry. We describe a direct method for real-time suppression of autofluorescence in frequency-domain fluorometry. The method uses a gated detector and the sample is excited by a pulsed train. The detector is gated on following each excitation pulse after a suitable time delay for decay of the prompt autofluorescence. Under the same experimental conditions a detectable reference signal is obtained by using a long lifetime standard with a known decay time. Because the sample and reference signals are measured under identical excitation, gating and instrumental conditions, the data can be analyzed as usual for frequency-domain data without further processing. We show by simulations that this method can be used to resolve single and multiexponential decays in the presence of short lifetime autofluorescence.
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Affiliation(s)
- J R Lakowicz
- University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, Maryland, 21201, USA
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43
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Lakowicz JR, Gryczynski I, Gryczynski Z, Tolosa L, Randers-Eichhorn L, Rao G. Polarization-based sensing of glucose using an oriented reference film. JOURNAL OF BIOMEDICAL OPTICS 1999; 4:443-9. [PMID: 23014617 PMCID: PMC6938719 DOI: 10.1117/1.429955] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We describe a new approach to glucose sensing using polarization measurements in the presence of a stretch-oriented reference film. The method relies on measurement of the polarized emission from the reference film and of a fluorophore which changes intensity in response to glucose. A glucose-sensitive fluorescent signal was provided by the glucose/galactose binding protein from E. coli. This protein was labeled with an environmentally sensitive fluorophore at a single genetically inserted cysteine residue, and displayed decreased fluorescence upon glucose binding. Using the protein and the reference film we observed glucose-sensitive polarization values for micromolar glucose concentrations. This method of polarization-based sensing is generic and can be used for any sensing fluorophore which displays a change in intensity. In principle, one can construct simple and economical devices for this type of glucose measurement. © 1999 Society of Photo-Optical Instrumentation Engineers.
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44
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Murtaza Z, Herman P, Lakowicz JR. Synthesis and spectral characterization of a long-lifetime osmium (II) metal-ligand complex: a conjugatable red dye for applications in biophysics. Biophys Chem 1999; 80:143-51. [PMID: 10483708 PMCID: PMC6901021 DOI: 10.1016/s0301-4622(99)00069-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
There is a need for luminescent probes, which display both long excitation and emission wavelengths and long decay times. We synthesized and characterized an osmium metal-ligand complex which displays a mean decay time of over 100 ns when bound to proteins. [Os(1,10-phenanthroline)2(5-amino-1,10-phenanthroline)[(PF6)2 can be excited at wavelengths up to 650 nm, and displays an emission maximum near 700 nm. The probe displays a modest but useful maximum fundamental anisotropy near 0.1 for 488-nm excitation, and thus convenient when using an argon ion laser. [Os(phen)2(aphen)](PF6)2 is readily activated to the isothiocyanate for coupling to proteins. When covalently linked to bovine serum albumin the intensity decay is moderately heterogeneous with a mean decay time of 145 ns. The anisotropy decay of the labeled protein displays a correlation time near 40 ns. This relatively long lifetime luminophores can be useful as a biophysical probe or in clinical applications such as fluorescence polarization immunoassays.
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Affiliation(s)
- Z Murtaza
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA
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45
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Abstract
We describe a new approach to fluorescence sensing which relies on visual determination the polarization. The sensing device consists of a fluorescent probe, which changes intensity in responses to the analyte, and an oriented fluorescent film, which is not affected by the analyte. An emission filter is selected to observe the emission from both the film and the sensing fluorophore. Changes in the probe intensity result in changes in the polarization of the combined emission from the sensor and reference. The degree of polarization can be detected visually using a dual polarizer with adjacent sections oriented orthogonally to each other. The emission passing through the dual polarizer is viewed with a second analyzing polarizer. This analyzer is rotated manually to yield equal intensities from both sides of the dual polarizer. This approach was used to measure the concentration of RhB in intralipid and to measure pH using 6-carboxyfluorescein. The analyzer angle is typically accurate to 1 degree, providing pH values accurate to +/- 0.1 pH unit at the midpoint of the titration curve. We also describe a method of visual polarization sensing that does not require an oriented film and that can use the same fluorophore for the sample and reference. These approaches to visual sensing are generic and can be applied to a wide variety of analytes for which fluorescent probes are available. Importantly, the devices are simple, with the only electronic component being the light source.
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Affiliation(s)
- I Gryczynski
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA
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46
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Lakowicz JR, Gryczynski I, Gryczynski Z, Dattelbaum JD. Anisotropy-based sensing with reference fluorophores. Anal Biochem 1999; 267:397-405. [PMID: 10036147 PMCID: PMC6816241 DOI: 10.1006/abio.1998.3029] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe a new approach to fluorescence sensing based on measurements of steady-state anisotropies in the presence of reference fluorophores with known anisotropies. The basic concept is that the anisotropy of a mixture reflects a weighted average of the anisotropies of the emitting species. By use of reference fluorophores the starting anisotropy can be near zero, or near 0.9 for oriented films which contain the reference fluorophore. Changing intensities of the analyte result in changes in anisotropy. A wide dynamic range of anisotropies is available because of the freedom to select high or low starting values. Anisotropy-based sensing was demonstrated for pH using 6-carboxyfluorescein and for protein affinity or immunoassay using an oriented film with high anisotropy and a protein labeled with a metal-ligand complex. The latter measurements were performed with a simple light-emitting diode excitation source without an excitation polarizer. The sensitive range of the assay can be adjusted by changing the intensity of the reference fluorophore. Anisotropy-based sensing can have numerous applications in clinical and analytical chemistry.
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Affiliation(s)
- J R Lakowicz
- University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, Maryland, 21201, USA
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47
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Tolosa L, Gryczynski I, Eichhorn LR, Dattelbaum JD, Castellano FN, Rao G, Lakowicz JR. Glucose sensor for low-cost lifetime-based sensing using a genetically engineered protein. Anal Biochem 1999; 267:114-20. [PMID: 9918662 PMCID: PMC6905191 DOI: 10.1006/abio.1998.2974] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe a glucose sensor based on a mutant glucose/galactose binding protein (GGBP) and phase-modulation fluorometry. The GGBP from Escherichia coli was mutated to contain a single cysteine residue at position 26. When labeled with a sulfhydryl-reactive probe 2-(4'-iodoacetamidoanilino)naphthalene-6-sulfonic acid, the labeled protein displayed a twofold decrease in intensity in response to glucose, with a dissociation constant near 1 microM glucose. The ANS-labeled protein displayed only a modest change in lifetime, precluding lifetime-based sensing of glucose. A modulation sensor was created by combining ANS26-GGBP with a long-lifetime ruthenium (Ru) metal-ligand complex on the surface of the cuvette. Binding of glucose changed the relative intensity of ANS26-GGBP and the Ru complex, resulting in a dramatic change in modulation at a low frequency of 2.1 MHz. Modulation measurements at 2.1 MHz were shown to accurately determine the glucose concentration. These results suggest an approach to glucose sensing with simple devices.
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Affiliation(s)
- L Tolosa
- Department of Biophysics, Department of Chemical and Biochemical Engineering, University of Maryland, 725 West Lombard Street, Baltimore, Maryland, 21201, USA
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Lakowicz JR, Castellano FN, Dattelbaum JD, Tolosa L, Rao G, Gryczynski I. Low-frequency modulation sensors using nanosecond fluorophores. Anal Chem 1998; 70:5115-21. [PMID: 9868909 PMCID: PMC6938645 DOI: 10.1021/ac980876c] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We describe a new approach to fluorescence sensing based on a mixture of fluorophores, one of which is sensitive to the desired analyte. If a long-lifetime analyte-insensitive fluorophore is mixed with a short-lifetime analyte-sensitive fluorophore, the modulation of the emission at conveniently low frequencies becomes equal to the fractional fluorescence intensity of the sensing fluorophore. Under these conditions, the modulation can be used to determine the analyte concentration. This can be used with any fluorophore that changes intensity in response to analyte and does not require the sensing fluorophore to display a change in lifetime. The feasibility of modulation-based sensing was demonstrated using mixtures of 6-carboxyfluorescein and [Ru 2,2'-(bipyridyl)3]2+ as a pH sensor and of the calcium probe Fluo-3 and [Ru 2,2'-(bipyridyl)3]2+ as a calcium sensor.
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Affiliation(s)
- J R Lakowicz
- Department of Molecular Biology & Biophysics, School of Medicine, University of Maryland, Baltimore 21201, USA
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Duchowicz R, Ferrer ML, Acuñ AU. Kinetic Spectroscopy of Erythrosin Phosphorescence and Delayed Fluorescence in Aqueous Solution at Room Temperature. Photochem Photobiol 1998. [DOI: 10.1111/j.1751-1097.1998.tb02505.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Terpetschnig E, Dattelbaum JD, Szmacinski H, Lakowicz JR. Synthesis and spectral characterization of a thiol-reactive long-lifetime Ru(II) complex. Anal Biochem 1997; 251:241-5. [PMID: 9299022 PMCID: PMC6942521 DOI: 10.1006/abio.1997.2253] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We report the synthesis and spectral properties of a long-lifetime luminescent Ru complex containing a sulfhydryl-reactive maleimide group, [Ru (2,2'-bipyridine)2(1, 10-phenanthroline-5-maleimide)](PF6)2. [Ru(bpy)2(phen-mi)]2+ was covalently linked to human serum albumin, immunoglobulin G, and beta-galactosidase. The lifetimes for probe bound to proteins were near 1.1 micros. In the absence of rotational motions, the probe displayed an anisotropy near 0.17 for excitation near 475 nm. Anisotropy decay data were used to determine rotational correlation times of the proteins, which showed local probe motions in addition to overall rotational diffusion. This long-lifetime sulfhydryl-reactive probe can be used to recover microsecond rotational motions and/or domain motions of proteins and/or macromolecular complexes.
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Affiliation(s)
- E Terpetschnig
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, Maryland 21201, USA
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