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Fluoreszenz - Neueste Forschungsartikel der Fachverlage


 
Aktuelle Fachartikel zur Fluoreszenz, sortiert nach Erscheinungsdatum.

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Journal of Fluorescence - published by Springer -
... is an international forum for peer-reviewed original articles that advance the practice of this established spectroscopic technique.



Aktuelle wissenschaftliche Fachartikel der genannten Journale:


Fluorescent Property of the Gd3+-Doped Terbium Complexes and Crystal Structure of [Tb(TPTZ)(H2O)6]Cl3·3H2O

Abstract  
The complex of Tb(TPTZ)Cl3·3H2O was synthesized by adding the ethyl alcohol solution of TbCl3 (1 mmol) to the solution of 2,4,6-tris-(2-pyridyl)-s-triazine(TPTZ,1 mmol) with constant stirring. The solution which had been filtered was kept at the room temperature for 4 weeks, and then a kind of transparent crystal was formed. Besides, nine kinds of solid complexes in the different molar proportion of terbium to gadolinium had been synthesized by adopting the similar method mentioned above. It was inferred from the elemental analysis and rare earth complexometry that the composition of these complexes is (TbxGdy)(TPTZ)Cl3·3H2O (x : y = 0.9 : 0.1, 0.8 : 0.2, 0.7 : 0.3, 0.6 : 0.4, 0.5 : 0.5, 0.4 : 0.6, 0.3 : 0.7, 0.2 : 0.8, 0.1 : 0.9). The absorption spectra and photoluminescence of the complexes were determined in dimethylsulfoxide (DMF), which showed that the excitation of the complexes is mostly ligand based. The triplet state energy level of TPTZ was measured, indicating that the lowest excitation state energy level of Tb(III) and the triplet state energy level of TPTZ match well each other. The fluorescent data indicated that the fluorescent emission intensity of Tb3+ ions would be enhanced in the complexes after terbium was doped with Gd3+ ion. When x : y was 0.5 : 0.5, the fluorescent emission intensity was the largest. The result obtained by testing the X-ray diffraction of the monocrystal revealed that the molecular formula of the mono-crystal complex is [Tb(TPTZ)(H2O)6]Cl3·3H2O. The number of metal ion coordinates is nine, and the tridentate TPTZ and six water molecules are bonded with terbium respectively. Besides, it also revealed that the monocrystal belongs to the monoclinic system, and space group Cc with the following unit cell parameters is a = 1.4785 (3) nm, b = 1.0547 (2) nm, c = 1.7385 (4) nm, β = 94.42 (3)°, V = 2.7028 (9) nm3 and Z = 4.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0619-z
  • Authors
    • Yan-Fang Zhao, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China
    • Yong-Liang Zhao, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China
    • Feng Bai, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China
    • Xiao-yan Wei, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China
    • Yong-sheng Zhou, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China
    • Mei-na Shan, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China
    • Huan-huan Li, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China
    • Rui-jun Ma, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China
    • Xiao-tao Fu, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China
    • Yan Du, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 China

Quelle: Journal of Fluorescence | 3 Mar 2010 | 9:09 am CET

Styryl Dyes as Two-Photon Excited Fluorescent Probes for DNA Detection and Two-Photon Laser Scanning Fluorescence Microscopy of Living Cells

Abstract  
Spectral-fluorescent properties of benzothiazole styryl monomer (Bos-3) and homodimer (DBos-21) dyes in presence of DNA were studied. The dyes enhance their fluorescence intensity in 2–3 orders of magnitude upon interaction with DNA. Studied styrylcyanines in DNA presence demonstrate rather high values of two-photon absorption (TPA) cross-section, which are comparable with the values of TPA cross section of the rhodamine dyes. An applicability of the styrylcyanines as probes for the fluorescence microscopy of living cells was studied. It was shown that both dyes are cell-permeable but homodimer dye DBos-21 produces noticeably brighter staining of HeLa cells comparing with monomer dye Bos-3. Molecules of DBos-21 initially bind to the nucleic acids- containing cell organelles (presumable mitochondria) and are able to penetrate into the cell nucleus. Thus, homodimer styryl DBos-21 dye is viewed as efficient stain for single-photon and two-photon excitation fluorescence imaging of living cells.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0630-4
  • Authors
    • Valentyna P. Tokar, Institute of Molecular Biology and Genetics of NASU 150 Zabolotnogo Str. 03143 Kyiv Ukraine
    • Mykhaylo Yu. Losytskyy, Institute of Molecular Biology and Genetics of NASU 150 Zabolotnogo Str. 03143 Kyiv Ukraine
    • Tymish Y. Ohulchanskyy, SUNY at Buffalo Institute for Lasers, Photonics and Biophotonics Buffalo NY 14260 USA
    • Dmytro V. Kryvorotenko, Institute of Molecular Biology and Genetics of NASU 150 Zabolotnogo Str. 03143 Kyiv Ukraine
    • Vladyslava B. Kovalska, Institute of Molecular Biology and Genetics of NASU 150 Zabolotnogo Str. 03143 Kyiv Ukraine
    • Anatoliy O. Balanda, Institute of Molecular Biology and Genetics of NASU 150 Zabolotnogo Str. 03143 Kyiv Ukraine
    • Igor M. Dmytruk, Physics Faculty, Kyiv Taras Shevchenko National University Build.1, academic Glushkov Ave., 2 03680 Kyiv Ukraine
    • Vadym M. Prokopets, Physics Faculty, Kyiv Taras Shevchenko National University Build.1, academic Glushkov Ave., 2 03680 Kyiv Ukraine
    • Sergiy M. Yarmoluk, Institute of Molecular Biology and Genetics of NASU 150 Zabolotnogo Str. 03143 Kyiv Ukraine
    • Valeriy M. Yashchuk, Physics Faculty, Kyiv Taras Shevchenko National University Build.1, academic Glushkov Ave., 2 03680 Kyiv Ukraine

Quelle: Journal of Fluorescence | 3 Mar 2010 | 9:09 am CET

Fluorescence Studies on New Potential Antitumoral Benzothienopyran-1-ones in Solution and in Liposomes

Abstract  
Fluorescence properties of four new potential antitumoral compounds, 3-arylbenzothieno[2,3-c]pyran-1-ones, were studied in solution and in lipid membranes of dipalmitoyl phosphatidylcholine (DPPC), egg yolk phosphatidylcholine (Egg-PC) and dioctadecyldimethylammonium bromide (DODAB). The 3-(4-methoxyphenyl)benzothieno[2,3-c]pyran-1-one (1c) exhibits the higher fluorescence quantum yields in all solvents studied. All compounds present a solvent sensitive emission, with significant red shifts in polar solvents for the methoxylated compounds. The results point to an ICT character of the excited state, more pronounced for compound 1c. Fluorescence (steady-state) anisotropy measurements of the compounds incorporated in liposomes of DPPC, DODAB and Egg-PC indicate that all compounds have two different locations, one due to a deep penetration in the lipid membrane and another corresponding to a more hydrated environment. In general, the methoxylated compounds prefer hydrated environments inside the liposomes. The 3-(4-fluorophenyl)benzothieno[2,3-c]pyran-1-one (1a) clearly prefers a hydrated environment, with some molecules located at the outer part of the liposome interface. On the contrary, the preferential location of 3-(2-fluorophenyl)benzothieno[2,3-c]pyran-1-one (1b) is in the region of lipid hydrophobic tails. Compounds with a planar geometry (1a and 1c) have higher mobility in the lipid membranes when phase transition occurs.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0607-3
  • Authors
    • Elisabete M. S. Castanheira, Universidade do Minho Centro de Física (CFUM) Campus de Gualtar 4710-057 Braga Portugal
    • M. Solange D. Carvalho, Universidade do Minho Centro de Física (CFUM) Campus de Gualtar 4710-057 Braga Portugal
    • Daniel J. G. Soares, Universidade do Minho Centro de Física (CFUM) Campus de Gualtar 4710-057 Braga Portugal
    • Paulo J. G. Coutinho, Universidade do Minho Centro de Física (CFUM) Campus de Gualtar 4710-057 Braga Portugal
    • Ricardo C. Calhelha, Universidade do Minho Centro de Química (CQ-UM) Campus de Gualtar 4710-057 Braga Portugal
    • Maria-João R. P. Queiroz, Universidade do Minho Centro de Química (CQ-UM) Campus de Gualtar 4710-057 Braga Portugal

Quelle: Journal of Fluorescence | 2 Mar 2010 | 11:04 am CET

Fluorescence Quenching Reaction of Polyvinylpyrrolidone-Eosin Y System for the Determination of Polyvinylpyrrolidone

Abstract  
In pH 1.8 ∼ 2.8 weak acid medium, polyvinylpyrrolidone (PVP) and Eosin Y reacted to form complex that could result in Eosin Y (EY) fluorescence quenching. The maximum quenching wavelength was at 542 nm. The fluorescence quenching (ΔF) was proportional to the concentration of polyvinylpyrrolidone in a certain range. The linear range, the correlation coefficient and the detection limit were 0.33 ∼ 2.0 μg•mL−1, 0.9994 and 99.6 ng•mL−1, respectively. The influences of the coexistence substances were tested and the results showed that the method had good selectivity. Therefore, a new method based on fluorescence quenching of eosin Y by PVP for the determination of trace PVP was developed. The method was sensitive, simple and rapid, which was applied to the determination of trace PVP in the beer with satisfactory results. The reaction mechanism was also discussed.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0615-3
  • Authors
    • Lihong Yu, Southwest University School of Chemistry and Chemical Engineering Chongqing 400715 China
    • Zhongfang Liu, Southwest University School of Chemistry and Chemical Engineering Chongqing 400715 China
    • Xiaoli Hu, Southwest University School of Chemistry and Chemical Engineering Chongqing 400715 China
    • Ling Kong, Southwest University School of Chemistry and Chemical Engineering Chongqing 400715 China
    • Shaopu Liu, Southwest University School of Chemistry and Chemical Engineering Chongqing 400715 China

Quelle: Journal of Fluorescence | 2 Mar 2010 | 11:04 am CET

Rotational Diffusion of Coumarins: A Dielectric Friction Study

Abstract  
The rotational diffusion of three probes: coumarin 522B (C522B), coumarin 307 (C307) and coumarin 138 (C138) with nearly identical size was studied at room temperature employing steady-state and time-resolved fluorescence anisotropy techniques in series of alcohols and alkanes. Experimental observations indicate faster rotation of C138 compared to the other two dyes in alcohols and a faster rotation of C522B than C307 in alkanes. The dielectric friction theories of Nee-Zwanzig (NZ) and van der Zwan-Hynes (ZH) were employed to estimate the friction experienced by the probes in alcohols, in addition to the mechanical friction calculated using Stokes-Einstein-Debye (SED) hydrodynamic with slip boundary condition and Dote-Kivelson-Schwartz (DKS) quasihydrodynamic theories. The observed reorientation times for the three probes do not follow the trend predicted by dielectric friction theories of NZ and ZH. The dipole moments determined from solvatochromic techniques were found to be different for the three probes.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0606-4
  • Authors
    • J. R. Mannekutla, Karnatak University Laser Spectroscopy Programme, Department of Physics Dharwad 580 003 India
    • Sanjeev R. Inamdar, Karnatak University Laser Spectroscopy Programme, Department of Physics Dharwad 580 003 India
    • B. G. Mulimani, Gulbarga University Gulbarga 585 106 India
    • M. I. Savadatti, Karnataka State Council for Higher Education Bangalore 560 001 India

Quelle: Journal of Fluorescence | 2 Mar 2010 | 11:04 am CET

Origin of Fluorescence Lifetimes in Human Serum Albumin. Studies on Native and Denatured Protein

Abstract  
Human serum albumin consists of a single polypeptide of 585 amino acid residues with 1 Trp residue. In the present work, we measured fluorescence lifetimes of the protein in both native and denatured states. The results indicate that Trp emission occurs with three lifetimes in both states. Lifetimes values and contribution to the global emission decay differ between the two states. Data are interpreted as the results of an emission occurring from three substructures of the tryptophan formed in the excited state. Two of these substructures are already present for the tryptophan free in solution. The third lifetime is the result of the interaction between the tryptophan residue and surrounding microenvironment. The populations of these substructures characterized by the pre-exponential parameters of the fluorescence lifetimes are dependent on the fluorophore microenvironment and on the global protein structure.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0597-1
  • Authors
    • Megdouda Amiri, Université des Sciences et Technologies de Lille Laboratoire de Biophysique Moléculaire Bâtiment C6. 59655 Villeneuve d’Ascq Cédex France
    • Kristina Jankeje, Université des Sciences et Technologies de Lille Laboratoire de Biophysique Moléculaire Bâtiment C6. 59655 Villeneuve d’Ascq Cédex France
    • Jihad René Albani, Université des Sciences et Technologies de Lille Laboratoire de Biophysique Moléculaire Bâtiment C6. 59655 Villeneuve d’Ascq Cédex France

Quelle: Journal of Fluorescence | 2 Mar 2010 | 11:04 am CET

Dynamics of Bacteriophage R17 Probed with a Long-Lifetime Ru(II) Metal-Ligand Complex

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 °C (<τ> = 491.8 ns) as compared to that at 25 °C (<τ> = 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 °C (2,574.9 ns) than at 25 °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.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0612-6
  • Authors
    • Myung Sup Kim, Pusan National University Department of Oral Biochemistry and Molecular Biology, School of Dentistry Yangsan 626-870 Korea
    • Jae Hui Kim, Pusan National University Department of Oral Biochemistry and Molecular Biology, School of Dentistry Yangsan 626-870 Korea
    • Beng Whwa Son, Pukyong National University Department of Chemistry Busan 608-737 Korea
    • Jung Sook Kang, Pusan National University Department of Oral Biochemistry and Molecular Biology, School of Dentistry Yangsan 626-870 Korea

Quelle: Journal of Fluorescence | 1 Mar 2010 | 7:10 pm CET

Sensitive Spectrofluorimetric Method of Analysis for Venlafaxine in Spiked Rat Plasma and Formulations

Abstract  
A simple, sensitive, accurate and affordable spectrofluorimetric method was developed and validated for the determination of venlafaxine, both in marketed preparations as well as in spiked rat plasma. Venlafaxine depicted strong native fluorescence property in freshly prepared 0.05 M sulphuric acid. The excitation and emission wavelengths were found to be 237.0 nm and 301.0 respectively. Effect of variations in pH, temperature, concentration, change in molarities of different solvents, and effect of excipients were studied. The calibration graph in case of dosage forms and in spiked plasma was found to be rectilinear in the concentrations of 15–600 ng/ml and 20–650 ng/ml respectively. The intra- day and inter-day accuracy measurements of VEN in formulations ranged from 0.29 to 0.44% and 0.27 to 0.49%, respectively. The intra-day and inter-day accuracy in measurement of VEN in plasma ranged from 0.062 to 2.26% and 0.52 to 2.32%, respectively. The limit of detection (LOD) was found to be 6.0 ng/mL and 4.0 ng/mL in plasma and formulations respectively. The mean recovery of VEN from plasma was 97.46.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0624-2
  • Authors
    • Sheikh Shahnawaz, Lloyd College Department of Pharmacy Knowledge park II Greater Noida 201306 India
    • Zaki Siddiqui, Dreamz College of Pharmacy Mandi Himachal Pradesh India
    • Quaisul Hoda, Lloyd College Department of Pharmacy Knowledge park II Greater Noida 201306 India

Quelle: Journal of Fluorescence | 26 Feb 2010 | 5:44 pm CET

Spectroscopic Detection of Tetracationic Porphyrin H-Aggregation on Polyanionic Matrix of Inorganic Polyphosphate

Abstract  
Self-assembly of tetracationic porphyrin TMPyP4+ onto polyanionic matrix of inorganic polyphosphate (PPS) in aqueous solutions has been studied in a wide range of molar phosphate-to-dye ratios using techniques of polarized fluorescence, absorption, resonance Raman spectroscopy and static light scattering. The binding of TMPyP4+ to PPS is characterized by the binding constant of 3 × 105 M−1 and the cooperativity parameter of about 150. The fluorescence quenching of the bound TMPyP4+ evidences the stacking of the porphyrine chromophores. Under the stoichiometric binding ratio TMPyP4+ forms extended continuous face-to-face aggregates (so-called H-aggregates) which manifest themselves by a blue shift (12 nm) and a large hypochromisity (51%) of the Soret absorption band. Each face-to-face TMPyP4+ stack is formed with participation of four PPS chains. Formation of such columnar aggregates is promoted by the ability of PPS chains to take a helix conformation where negative charges are arranged along two oppositely situated rows with intercharge distance of 0.36 nm which corresponds to the thickness of the porphyrin π-electronic system. The ability of each PPS strand to be template for formation of two porphyrin stacks results in the integration of the adjacent stacks into higher-order aggregates which dimension was estimated from the fluorescence polarization data.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0609-1
  • Authors
    • Victor N. Zozulya, B. Verkin Institute for Low Temperature Physics & Engineering of NAS of Ukraine Department of Molecular Biophysics 47 Lenin ave. 61103 Kharkov Ukraine
    • Olga A. Ryazanova, B. Verkin Institute for Low Temperature Physics & Engineering of NAS of Ukraine Department of Molecular Biophysics 47 Lenin ave. 61103 Kharkov Ukraine
    • Igor M. Voloshin, B. Verkin Institute for Low Temperature Physics & Engineering of NAS of Ukraine Department of Molecular Biophysics 47 Lenin ave. 61103 Kharkov Ukraine
    • Alexandr Yu. Glamazda, B. Verkin Institute for Low Temperature Physics & Engineering of NAS of Ukraine Department of Molecular Biophysics 47 Lenin ave. 61103 Kharkov Ukraine
    • Victor A. Karachevtsev, B. Verkin Institute for Low Temperature Physics & Engineering of NAS of Ukraine Department of Molecular Biophysics 47 Lenin ave. 61103 Kharkov Ukraine

Quelle: Journal of Fluorescence | 25 Feb 2010 | 6:56 pm CET

Measurement Conditions for Flow Cytometry Analyses of Cell Lines from Urological Carcinomas

Abstract  
Prerequisites for successful flow cytometry investigations are specific antibodies labeled with appropriate fluorochromes and negligible autofluorescence of the untreated cells at the wavelength of interest. The aim of this study was (a) to characterize frequently used urological carcinoma cell lines with regard to their autofluorescence properties, (b) to demonstrate the autofluorescence as a serious interfering factor on FACS analysis of urological carcinoma cell lines and (c) to suggest an alternative to avoid interfering autofluorescence. Twenty-one cell lines originating from prostate carcinoma, renal cell carcinoma and bladder cancer were included in this study. The various cell lines were read on a flow cytometer in comparison to human erythrocytes as cells with low fluorescence intensity. Urological cell lines show a high autofluorescence when flow cytometry analyses are performed at the frequently used excitation wavelengths at 405 and 488 nm. At excitation wavelength of 633 nm, this problem was reduced and most of the cell lines (14/21) were without autofluorescence at the emission wavelength of 785 nm. In addition, with a spectrofluorometer three exemplary cell lysates were investigated. The above observations were confirmed. The dye APC-Cy7 is one suitable fluorochrome for successful investigation under these measurement conditions.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0621-5
  • Authors
    • Angelika Tölle, Charité–Universitätsmedizin Berlin Department of Urology Charitéplatz 1 10117 Berlin Germany
    • Ziyad Abdallah, Charité—Universitätsmedizin Berlin Institute of Transfusion Medicine 10117 Berlin Germany
    • Klaus Jung, Berlin Institute for Urologic Research 10117 Berlin Germany
    • Hans Bäumler, Charité—Universitätsmedizin Berlin Institute of Transfusion Medicine 10117 Berlin Germany

Quelle: Journal of Fluorescence | 25 Feb 2010 | 6:56 pm CET

Synthesis and Fluorescence Properties of Donor-Acceptor-Substituted Novel Dipyrazolo[3,4-b:3′,4′-d]Pyridines (DPP)

Abstract  
A rapid and efficient method for the synthesis of novel dipyrazolo[3,4-b:3′,4′-d]pyridines (DPP) from pyrazolo[3,4-b]pyridine was successfully developed. The DPP derivative was further N-alkylated (6, 8) as well as N-linked with amino acids (13) and their photophysical properties were studied along with N-aryl DPP 4 and observed that the chromophores at C4 position in the aryl ring changed the absorption and emission λmax.

  • Content Type Journal Article
  • Category Rapid Communication
  • DOI 10.1007/s10895-010-0622-4
  • Authors
    • Madhukar N. Jachak, B.H. Commerce and A.M. Science College Organic Chemistry Research Center, Department of Chemistry, K.R.T. Arts Gangapur Road Nashik 422002 MS India
    • Sandeep M. Bagul, B.H. Commerce and A.M. Science College Organic Chemistry Research Center, Department of Chemistry, K.R.T. Arts Gangapur Road Nashik 422002 MS India
    • Dilip R. Birari, B.H. Commerce and A.M. Science College Organic Chemistry Research Center, Department of Chemistry, K.R.T. Arts Gangapur Road Nashik 422002 MS India
    • Maruti G. Ghagare, B.H. Commerce and A.M. Science College Organic Chemistry Research Center, Department of Chemistry, K.R.T. Arts Gangapur Road Nashik 422002 MS India
    • Muddassar A. Kazi, B.H. Commerce and A.M. Science College Organic Chemistry Research Center, Department of Chemistry, K.R.T. Arts Gangapur Road Nashik 422002 MS India
    • Raghunath B. Toche, B.H. Commerce and A.M. Science College Organic Chemistry Research Center, Department of Chemistry, K.R.T. Arts Gangapur Road Nashik 422002 MS India
    • Vijayavitthal T. Mathad, Mega Fine Pharma Pvt. Ltd. 201, Lakhmapur, Dindori Nashik 422202 MS India

Quelle: Journal of Fluorescence | 25 Feb 2010 | 6:56 pm CET

A Coumarin-Based Fluorescent Chemosensor for Zn2+ in Aqueous Ethanol Media

Abstract  
A coumarin-based fluorescent chemosensor 1 for Zn2+ was designed and synthesized. Compound 1 exhibits lower background fluorescence due to intramolecular photoinduced electron transfer. However, upon mixing with Zn2+ in 30% (v/v) aqueous ethanol, a “turn-on” fluorescence emission is observed. The fluorescence emission increases linearly with Zn2+ concentration in the range 0.5–10 μmol L−1 with a detection limit of 0.29 μmol L−1. No remarkable emission enhancement was, however, observed for other metal ions. The proposed chemosensor was applied to the determination of Zn2+ in water samples with satisfactory results.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0628-y
  • Authors
    • Zhuan Su, Northwest University Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry Xi’an 710069 China
    • Kangyu Chen, Northwest University Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry Xi’an 710069 China
    • Yuan Guo, Northwest University Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry Xi’an 710069 China
    • Haiping Qi, Northwest University Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry Xi’an 710069 China
    • Xiao-Feng Yang, Northwest University Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry Xi’an 710069 China
    • Minglei Zhao, Northwest University Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry Xi’an 710069 China

Quelle: Journal of Fluorescence | 25 Feb 2010 | 7:56 am CET

Luminescence in Colorless, Transparent, Thermally Stable Thin Films of Eu3+ and Tb3+ β-diketonates in Hybrid Inorganic–Organic Zinc-based Sol–Gel Matrix

Abstract  
Luminescent zinc-based hybrid inorganic–organic films with rare--earth (RE) complexes have been prepared using a non-alkoxide sol–gel process. The films were fabricated by the dip-coating method starting from zinc acetate dihydrate, rare earth chloride, lactic acid as hydrolytic catalyst, and anhydrous ethanol. The β-diketones thenoylltrifluoroacetone (Httfa) and dibenzoylmethane (Hdbm) were used as ligands to Eu3+ and Tb3+, respectively. After deposition of the first layer, the films were fired at temperatures between 50 and 300 °C, in air. Photophysical properties such as excitation, emission and emission, lifetimes were determined for the films obtained in different conditions. Eu3+/ttfa and Tb3+/dbm films fired at 300 and 250 °C, respectively, are still transparent and gave rise to intense emission when excited through the ligand (antenna effect).

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0616-2
  • Authors
    • Renata Figueredo Martins, FFCLRP-USP Department of Chemistry Av. dos Bandeirantes, 3900 CEP 14040-901 Ribeirão Preto SP Brazil
    • Rodrigo Ferreira Silva, FFCLRP-USP Department of Chemistry Av. dos Bandeirantes, 3900 CEP 14040-901 Ribeirão Preto SP Brazil
    • Rogéria Rocha Gonçalves, FFCLRP-USP Department of Chemistry Av. dos Bandeirantes, 3900 CEP 14040-901 Ribeirão Preto SP Brazil
    • Osvaldo Antonio Serra, FFCLRP-USP Department of Chemistry Av. dos Bandeirantes, 3900 CEP 14040-901 Ribeirão Preto SP Brazil

Quelle: Journal of Fluorescence | 24 Feb 2010 | 7:51 am CET

Fluorescent Study of Human Blood Plasma Albumin Alterations Induced by Ionizing Radiation

Abstract  
The use of hydrophobic fluorescent probe ABM (benzanthrone derivative) and albumin autofluorescence allowed show conformational alterations in Chernobyl clean-up workers blood plasma. Results obtained in 1996–1997 suggest that acidic expansion of plasma albumin takes place. Latest data (2006–2008) result in splitting of albumin alterations onto two stages - acidic expansion and N-F transition. The N-F transition is accompanied by the blue shift of fluorescence spectra and dehydration of tryptophanyl region of albumin molecule. In 2007 obtained.patterns of ABM spectra had never been previously seen in examined healthy individuals or patients with tuberculosis, multiple sclerosis, rheumatoid arthritis, etc. Patterns of ABM fluorescence spectra are associated with conformational changes of blood plasma albumin. The use of probe ABM and albumin auto-fluorescence allowed show conformational alterations in albumin of Chernobyl clean-up workers blood plasma. It is necessary to note that all investigated parameters significantly differ in observed groups of patients. These findings reinforce our understanding that the blood plasma albumin is a significant biological target of radiation. It may be concluded that fluorescence characteristics are representative of radiation induced albumin alterations and its carrier function.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0608-2
  • Authors
    • Elena M. Kirilova, Daugavpils University Daugavpils Latvia
    • Inta Kalnina, Daugavpils University Daugavpils Latvia
    • Tija Zvagule, Riga Stradins University Riga Latvia
    • Natalija Gabruseva, University of Latvia Biomedical Research and Study Centre Riga Latvia
    • Natalja Kurjane, Riga Stradins University Riga Latvia
    • Irina I. Solomenikova, Daugavpils University Daugavpils Latvia

Quelle: Journal of Fluorescence | 24 Feb 2010 | 7:51 am CET

Synthesis and Luminescence Properties of Two Novel Lanthanide (III) Perchlorate Complexes with Bis(benzoylmethyl) Sulfoxide and Benzoic Acid

Abstract  
Two novel ternary rare earth complexes of Tb(III) and Dy(III) perchlorates with bis(benzoylmethyl) sulfoxide (L) and benzoic acid (L′) had been synthesized and characterized by elemental analysis, coordination titration analysis, molar conductivity, IR, TG-DSC, 1HNMR and UV spectra. The results indicated that the composition of these complexes was REL5L′(ClO4)2·nH2O (RE= Tb(III), Dy(III); L=C6H5COCH2SOCH2COC6H5, L′=C6H5COO; n = 6,8). The fluorescence spectra illustrated that the ternary rare earth complexes presented stronger fluorescence intensities, longer lifetimes and higher fluorescence quantum efficiencies than the binary rare earth complexes REL5·(ClO4)3·2H2O. After the introduction of the second ligand benzoic acid group, the relative fluorescence emission intensities and fluorescence lifetimes of the ternary complexes REL5L′(ClO4)2·nH2O (RE= Tb(III), Dy(III)) enhanced more obviously than the binary complexes. This indicated that the presence of both organic ligands bis(benzoylmethyl) sulfoxide and the second ligand benzoic acid could sensitize fluorescence intensities of rare earth ions, and the introduction of benzoic acid group was resulted in the enhancement of the fluorescence properties of the ternary rare earth complexes. The phosphorescence spectra were also discussed.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0633-1
  • Authors
    • Wen-Xian Li, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 People’s Republic of China
    • Wen-Juan Chai, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 People’s Republic of China
    • Xiao-Jun Sun, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 People’s Republic of China
    • Tie Ren, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 People’s Republic of China
    • Xiao-Yan Shi, Inner Mongolia University College of Chemistry and Chemical Engineering Hohhot 010021 People’s Republic of China

Quelle: Journal of Fluorescence | 24 Feb 2010 | 7:51 am CET

Polarity Assessment of Thermoresponsive Poly(NIPAM-co-NtBA) Copolymer Films Using Fluorescence Methods

Abstract  
The in-situ, non-contact, and non-destructive measurement of the physicochemical properties such as the polarity of thin, hydrophilic polymer films is desirable in many areas of polymer science. Polarity is a complex factor and encompasses a range of non-covalent interactions including dipolarity/polarizability and hydrogen bonding. A polarity measurement method based on fluorescence would be ideal, but the key challenge is to identify suitable probes which can accurately measure specific polarity related parameters. In this manuscript we assess a variety of fluorophores for measuring the polarity of a series of relatively hydrophilic, thermoresponsive N-isopropylacrylamide/N-tert-butylacrylamide (NIPAM/NtBA) copolymers. The emission properties of both pyrene and 3-Hydroxyflavone (3-HF) based fluorophores were measured in dry polymer films. In the case of pyrene, a relatively weak, linear relationship between polymer composition and the ratio of the first to the third vibronic band of the emission spectrum (I1/I3) is observed, but pyrene emission is very sensitive to temperature and thus not suitable for robust polarity measurements. The 3-HF fluorophores which can undergo an excited-state intramolecular proton transfer (ESIPT) reaction have a dual band fluorescence emission that exhibits strong solvatochromism. Here we used 4′-diethylamino-3-hydroxyflavone (FE), 5,6-benzo-4′-diethylamino-3-hydroxyflavone (BFE), and 4´-diethylamino-3-hydroxy-7-methoxyflavone (MFE). The log ratio of the dual band fluorescence emission (log (IN*/IT*)) of 3-HF doped, dry, NIPAM-NtBA copolymer films were found to depend linearly on copolymer composition, with increasing hydrophobicity (greater NtBA fraction) leading to a decrease in the value of log (IN*/IT*). However, the ESIPT process in the polymer matrix was found to be irreversible, non-equilibrated and occurs over a much longer timescale in comparison to the results previously reported for liquid solvents.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0613-5
  • Authors
    • Boguslaw Szczupak, National University of Ireland, Galway Nanoscale Biophotonics Laboratory, School of Chemistry Galway Ireland
    • Alan G. Ryder, National University of Ireland, Galway Nanoscale Biophotonics Laboratory, School of Chemistry Galway Ireland
    • Denisio M. Togashi, National University of Ireland, Galway Nanoscale Biophotonics Laboratory, School of Chemistry Galway Ireland
    • Andrey S. Klymchenko, Université de Strasbourg Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Faculté de Pharmacie Illkirch France
    • Yuri A. Rochev, National University of Ireland, Galway National Centre for Biomedical Engineering Sciences Galway Ireland
    • Alexander Gorelov, University College Dublin Department of Chemistry Dublin Ireland
    • Thomas J. Glynn, National University of Ireland, Galway School of Physics Galway Ireland

Quelle: Journal of Fluorescence | 24 Feb 2010 | 7:51 am CET

Study of Blood Porphyrin Spectral Profile for Diagnosis of Chronic Renal Failure

Abstract  
The progression to end-stage renal failure is independent of the initial pathogenic mechanism. Metabolic acidosis is a common consequence of chronic renal failure that results from inadequate ammonium excretion and decreased tubular bicarbonate reabsorption. Protoporphyrin IX (PpIX) is the immediate metabolic precursor of the heme molecule. The purpose of this study was to evaluate the levels of erythrocytes protoporphyrin IX at an animal model during progressive renal disease. A total of 36 eight-week-old male Wistar rats were divided into six groups: Normal, 4 and 8 weeks after 5/6 nephrectomy (NX). Renal function was evaluated by creatinine clearance and plasma creatinine levels. The autofluorescence of erythrocytes porphyrin of healthy and NX rats was analyzed using fluorescence spectroscopy. Emission spectra were obtained by exciting the samples at 405 nm. Significant differences between normal and NX rats autofluorescence shape occurred in the 600–700 nm spectral region. A correlation was observed between emission band intensity at 635 nm and progression of renal disease.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0600-x
  • Authors
    • Vivian Regina Tristão, Universidade Federal de São Paulo—UNIFESP-EPM Disciplina Nefrologia, Departamento de Medicina São Paulo Brazil
    • Fernando Felippe de Carvalho, Universidade Federal de São Paulo—UNIFESP-EPM Disciplina Nefrologia, Departamento de Medicina São Paulo Brazil
    • Cinthia Zanini Gomes, IPEN-CNEN-SP Instituto de Pesquisas Energéticas e Nucleares São Paulo Brazil
    • Adriana Regina Miranda, IPEN-CNEN-SP Instituto de Pesquisas Energéticas e Nucleares São Paulo Brazil
    • Cíntia C. Vequi-Suplicy, Instituto de Física da Universidade de São Paulo—USP São Paulo Brazil
    • Maria Teresa Lamy, Instituto de Física da Universidade de São Paulo—USP São Paulo Brazil
    • Nestor Schor, Universidade Federal de São Paulo—UNIFESP-EPM Disciplina Nefrologia, Departamento de Medicina São Paulo Brazil
    • Maria Helena Bellini, Universidade Federal de São Paulo—UNIFESP-EPM Disciplina Nefrologia, Departamento de Medicina São Paulo Brazil

Quelle: Journal of Fluorescence | 23 Feb 2010 | 8:51 am CET

Photoactive Ru Complex Embedded in Mesostructured MCM-41 Nanoparticles

Abstract  
The synthesis and characterization of photoactive hybrid materials based on [Ru(bpy)3]2+ physically adsorbed within the channels of mesoporous MCM-41 silica nanoparticles is presented. A set of photoactive mesostructured hybrids with different guest loading has been prepared and characterized by X-ray diffraction, High Resolution Transmission Electron Microscopy, volumetric analyses, Diffuse Reflectance UV-Vis and Photoluminescence spectroscopies and lifetime measurements. The hybrids synthesis and the washing procedures, performed to investigate the host-guest interaction and the stability of the complex within the mesopores, didn’t affect the integrity of the structure and morphology of MCM-41 nanoparticles. The dispersion of [Ru(bpy)3]2+ within the channels varied depending on the loading value and this is reflected in the different and peculiar photoluminescence features of the resulting hybrid materials. Photoluminescence spectroscopy evidenced that the use of MCM-41 nanoparticles ensures a better dispersion of the complex within the mesopores, if compared with traditional MCM-41. Further studies are in progress to investigate the interesting and promising features exhibited by such photoactive systems for advanced applications of electrochemiluminescence in optoelectronics and diagnostics.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0605-5
  • Authors
    • Emanuela Bottinelli, University of Turin Dipartimento di Chimica IFM and NIS, Centre of Excellence via P. Giuria 7 10125 Torino Italy
    • Ivana Miletto, University of Turin Dipartimento di Chimica IFM and NIS, Centre of Excellence via P. Giuria 7 10125 Torino Italy
    • Giuseppe Caputo, University of Turin Dipartimento di Chimica IFM and NIS, Centre of Excellence via P. Giuria 7 10125 Torino Italy
    • Salvatore Coluccia, University of Turin Dipartimento di Chimica IFM and NIS, Centre of Excellence via P. Giuria 7 10125 Torino Italy
    • Enrica Gianotti, University of Turin Dipartimento di Chimica IFM and NIS, Centre of Excellence via P. Giuria 7 10125 Torino Italy

Quelle: Journal of Fluorescence | 23 Feb 2010 | 8:50 am CET

The Role of the Eu3+ Concentration on the SrMoO4:Eu Phosphor Properties: Synthesis, Characterization and Photophysical Studies

Abstract  
SrMoO4 doped with rare earth are still scarce nowadays and have attracted great attention due to their applications as scintillating materials in electro-optical like solid-state lasers and optical fibers, for instance. In this work Sr1−xEuxMoO4 powders, where x = 0.01; 0.03 and 0.05, were synthesized by Complex Polymerization (CP) Method. The structural and optical properties of the SrMoO4:Eu3+ were analyzed by powder X-ray diffraction patterns, Fourier Transform Infra-Red (FTIR), Raman Spectroscopy, and through Photoluminescent Measurements (PL). Only a crystalline scheelite-type phase was obtained when the powders were heat-treated at 800 °C for 2 h, 2θ = 27.8° (100% peak). The excitation spectra of the SrMoO4:Eu3+Em. = 614 nm) presented the characteristic band of the Eu3 + 5L6 transition at 394 nm and a broad band at around 288 nm ascribed to the charge-transfer from the O (2p) state to the Mo (4d) one in the SrMoO4 matrix. The emission spectra of the SrMoO4:Eu3+ powders (λExc. = 394 and 288 nm) show the group of sharp emission bands among 523–554 nm and 578–699 nm, assigned to the 5D17F0,1and 2 and 5D07F0,1,2,3 and 4, respectively. The band related to the 5D07F0 transition indicates the presence of Eu3+ site without inversion center. This hypothesis is strengthened by the fact that the band referent to the 5D07F2 transition is the most intense in the emission spectra.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0604-6
  • Authors
    • Ana Paula A. Marques, Universidade Federal de São Carlos Laboratório Interdisciplinar de Eletroquímica e Cerâmica, Centro Multidisciplinar de Desenvolvimento de Materiais Cerâmicos, Departamento de Química C. Postal 676 13565-905 São Carlos SP Brazil
    • Marcos Takashi S. Tanaka, Universidade Federal de São Carlos Laboratório Interdisciplinar de Eletroquímica e Cerâmica, Centro Multidisciplinar de Desenvolvimento de Materiais Cerâmicos, Departamento de Química C. Postal 676 13565-905 São Carlos SP Brazil
    • Elson Longo, Universidade Estadual Paulista CMDMC, LIEC, Instituto de Química 14801-907 Araraquara SP Brazil
    • Edson R. Leite, Universidade Federal de São Carlos Laboratório Interdisciplinar de Eletroquímica e Cerâmica, Centro Multidisciplinar de Desenvolvimento de Materiais Cerâmicos, Departamento de Química C. Postal 676 13565-905 São Carlos SP Brazil
    • Ieda Lucia Viana Rosa, Universidade Federal de São Carlos Laboratório Interdisciplinar de Eletroquímica e Cerâmica, Centro Multidisciplinar de Desenvolvimento de Materiais Cerâmicos, Departamento de Química C. Postal 676 13565-905 São Carlos SP Brazil

Quelle: Journal of Fluorescence | 23 Feb 2010 | 8:50 am CET

Investigation of the Europium Emission Spectra of the Europium-Oxytetracycline Complex in the Presence of Human Low-Density Lipoproteins

Abstract  
Low-Density Lipoprotein (LDL), often known as “bad cholesterol” is one of the responsible to increase the risk of coronary arterial diseases. For this reason, the cholesterol present in the LDL particle has become one of the main parameters to be quantified in routine clinical diagnosis. A number of tools are available to assess LDL particles and estimate the cholesterol concentration in the blood. The most common methods to quantify the LDL in the plasma are the density gradient ultracentrifugation and nuclear magnetic resonance (NMR). However, these techniques require special equipments and can take a long time to provide the results. In this paper, we report on the increase of the Europium emission in Europium-oxytetracycline complex aqueous solutions in the presence of LDL. This increase is proportional to the LDL concentration in the solution. This phenomenum can be used to develop a method to quantify the number of LDL particles in a sample. A comparison between the performances of the oxytetracycline and the tetracycline in the complexes is also made.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0602-8
  • Authors
    • Luciane dos Santos Teixeira, IPEN/CNEN-SP Centro de Lasers e Aplicações São Paulo SP Brazil
    • Andréa Nastri Grasso, IPEN/CNEN-SP Centro de Lasers e Aplicações São Paulo SP Brazil
    • Andrea Moreira Monteiro, Universidade de São Paulo Instituto de Ciências Biomédicas, ICB–São Paulo São Paulo SP Brazil
    • Antonio M. Figueiredo Neto, Universidade de São Paulo Instituto de Física São Paulo SP Brazil
    • Nilson Dias Vieira, IPEN/CNEN-SP Centro de Lasers e Aplicações São Paulo SP Brazil
    • Magnus Gidlund, Universidade de São Paulo Instituto de Ciências Biomédicas, ICB–São Paulo São Paulo SP Brazil
    • Juliana Steffens, Universidade de São Paulo Instituto de Ciências Biomédicas, ICB–São Paulo São Paulo SP Brazil
    • Lilia Coronato Courrol, Universidade Federal de São Paulo—UNIFESP Campus Diadema, Rua Arthur Ridel, 275, Eldorado Diadema SP Brazil

Quelle: Journal of Fluorescence | 23 Feb 2010 | 8:50 am CET

Synthesis, Spectroscopy and Photochemistry of Novel Branched Fluorescent Nitro-Stilbene Derivatives with Benzopheonone Groups

Abstract  
In this article, we presented novel nitro-stilbene derivatives with one or two benzophenone groups as photoinitiators via multi-steps synthesis. The ultraviolet/visible spectroscopy and the emission spectroscopy of the compounds were determined in various solvents. The results showed that the ultraviolet/visible absorption spectroscopy of the derivatives with benzophenone moiety displayed overlap effects of nitro-stilbene and benzophenone parts. In non-polar solvents, the derivatives exhibited strong emission, while they displayed weak emission in modest and strong polar solvents. Dyes-linked benzopheonone groups displayed stronger fluorescence emission than simple chromophore parent molecules. Visible-light photoinitiating effects of the derivatives were investigated extensively. Methyl methacrylate could be photoinitiated efficiently by the derivatives with benzophenone moieties at very low concentration, even at 1 × 10−5 mol/L. While the photopolymerization efficiency of styrene initiated by the derivatives was lower than that of methyl methacrylate. Our results showed that the dye-linked photoinitators had more efficient photoinitiating than the simple mixture of dye and photoinitator. Furthermore, the derivative with two benzophenone groups displayed more excellent phototiniatiating effects than the derivative with one benzophenone group. Thermodynamics driving for the occurrence of visible-light photoinduced intramolecular electron transfer from chromophore part to benzophenone part was evaluated. Benzopinacol moiety produced in photoreaction was confirmed by nuclear magnetic resonant spectroscopy. Thermal stability of the derivatives was analyzed.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0611-7
  • Authors
    • Fang Gao, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China
    • Jian Liu, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China
    • Huayong Peng, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China
    • Nvdan Hu, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China
    • Hongru Li, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China
    • Shengtao Zhang, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China

Quelle: Journal of Fluorescence | 23 Feb 2010 | 8:50 am CET

Water Stress Response of Conventional and Transgenic Soybean Plants Monitored by Chlorophyll a Fluorescence

Abstract  Two soybean cultivars, one conventional and a glyphosate-tolerant (transgenic), were submitted to the water stress and the chlorophyll a fluorescence induced by UV light was monitored daily during 16 days. In this work, 40 pots in total, 20 per cultivar were used in the investigation. Each cultivar was divided in two groups, the control group and the group submitted to the water stress. The stress response of the cultivars was monitored by red to far-red fluorescence ratio. The data indicate that the water stress induced the earliest changes on the fluorescence ratio and chlorophyll content for the conventional cultivar. In addition, a comparative analysis of the fluorescence ratios of the cultivars reveals that conventional plants have higher chlorophyll content than transgenic ones. This result might be useful in the development of methodologies able to distinguish conventional to transgenic apart.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0594-4
  • Authors
    • A. R. L. Caires, Universidade Federal da Grande Dourados—UFGD Grupo de Óptica Aplicada CP 533 79804–970 Dourados MS Brazil
    • M. D. Scherer, Universidade Federal da Grande Dourados—UFGD Grupo de Óptica Aplicada CP 533 79804–970 Dourados MS Brazil
    • T. S. B. Santos, Universidade Federal da Grande Dourados—UFGD Grupo de Óptica Aplicada CP 533 79804–970 Dourados MS Brazil
    • B. C. A. Pontim, Universidade Federal da Grande Dourados—UFGD Laboratório de Fitopatologia CP 533 79804–970 Dourados MS Brazil
    • W. L. Gavassoni, Universidade Federal da Grande Dourados—UFGD Laboratório de Fitopatologia CP 533 79804–970 Dourados MS Brazil
    • S. L. Oliveira, Universidade Federal da Grande Dourados—UFGD Grupo de Óptica Aplicada CP 533 79804–970 Dourados MS Brazil

Quelle: Journal of Fluorescence | 9 Feb 2010 | 6:45 pm CET

On the Photophysical Properties of New Luminol Derivatives and their Synthetic Phthalimide Precursors

Abstract  The photophysical properties of a series of structurally related 4-aminophthalimides and the corresponding 5-aminophthalic hydrazides (luminols) are reported. Absorption, steady-state, and time-resolved fluorescence spectra of luminols exhibited substitution, solvent, and pH dependence. Singlet lifetimes have been determined by time-resolved laser flash spectroscopy. UV spectra in gas phase and DMSO solution were calculated by TD-DFT which revealed the existence of two low-energy excited singlet states with strong pH-sensitivity.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-010-0598-0
  • Authors
    • Raúl Pérez-Ruiz, University of Cologne Department of Chemistry Greinstr. 4 50939 Köln Germany
    • Robert Fichtler, University of Cologne Department of Chemistry Greinstr. 4 50939 Köln Germany
    • Yrene Diaz Miara, University of Cologne Department of Chemistry Greinstr. 4 50939 Köln Germany
    • Matthieu Nicoul, University of Cologne Department of Physics I Zülpicher Str. 77 50937 Köln Germany
    • Dominik Schaniel, University of Cologne Department of Physics I Zülpicher Str. 77 50937 Köln Germany
    • Helfried Neumann, Leibniz-Institute of Catalysis Albert-Einstein-Str. 29a 18059 Rostock Germany
    • Matthias Beller, Leibniz-Institute of Catalysis Albert-Einstein-Str. 29a 18059 Rostock Germany
    • Dirk Blunk, University of Cologne Department of Chemistry Greinstr. 4 50939 Köln Germany
    • Axel G. Griesbeck, University of Cologne Department of Chemistry Greinstr. 4 50939 Köln Germany
    • Axel Jacobi von Wangelin, University of Cologne Department of Chemistry Greinstr. 4 50939 Köln Germany

Quelle: Journal of Fluorescence | 28 Jan 2010 | 7:01 pm CET

Application of Fluorescence to the Study of Crude Petroleum

Abstract  Crude petroleum oils are complex mixtures of different compounds (mainly organic), which are obtained from an extensive range of different geological sources. The fluorescence of crude petroleum oils derives largely from the aromatic hydrocarbon fraction, and this fluorescence emission is strongly influenced by the chemical composition (e.g., fluorophore and quencher concentrations) and physical characteristics (e.g., viscosity and optical density) of the oil. The fluorescence spectroscopy (FS) is increasingly used in petroleum technology due the availability of better optical detection techniques, because FS offers high sensitivity, good diagnostic potential, and relatively simple instrumentation. In this work we analyzed crude petroleum at different dilution in Nujol, a transparent mineral oil. The main objective of this work was to verify the possibility to measure crude oil emission spectroscopic without use of volatile solvents. The mixtures of nujol with different -crude oil concentrations were measured with a 10 mm optical path cuvette thus simplifying the fluorescence spectroscopy signal detection. The emission spectra were obtained by exciting the samples with a 400 W Xenon lamp at 350 nm, 450 nm and 532 nm. The emissions of the samples were collected perpendicularly with the excitation axis.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0586-4
  • Authors
    • Juliana Steffens, Polytechnic School, University of São Paulo Department of Chemical Engineering São Paulo Brazil
    • Eduardo Landulfo, Nuclear and Energetic Research Institute São Paulo Brazil
    • Lilia Coronato Courrol, Nuclear and Energetic Research Institute São Paulo Brazil
    • Roberto Guardani, Polytechnic School, University of São Paulo Department of Chemical Engineering São Paulo Brazil

Quelle: Journal of Fluorescence | 28 Jan 2010 | 7:01 pm CET

6,7-Difluoro-1,4-dihydro-1-methyl-4-oxo-3-quinolinecarboxylic Acid, a Newly Designed Fluorescence Enhancement-Type Derivatizing Reagent for Amino Compounds

Abstract  
A novel fluorescence enhancement-type derivatizing reagent for amino compounds, 6,7-difluoro-1,4-dihydro-1-methyl-4-oxo-3-quinolinecarboxylic acid (FMQC), was developed. FMQC reacts with aliphatic primary amino compounds to afford strong fluorescent derivatives having high photo-and thermo-stabilities. The FMQC derivatives of amino compounds showed 12–159 times higher fluorescence quantum efficiencies than those of FMQC in aqueous and polar organic media. Additionally, the absorption and fluorescence emission wavelength of the derivatives are red-shifted from those of FMQC. These differences in the fluorescence properties between FMQC and the fluorescent derivative enabled the simple and highly sensitive determination of amino compounds without removing any excess unreacted FMQC by using a simple spectrofluorometer as well as HPLC.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0596-2
  • Authors
    • Junzo Hirano, Kyushu University Graduate School of Pharmaceutical Sciences 3-1-1 Maidashi Higashi-ku Fukuoka 812-8582 Japan
    • Kenji Hamase, Kyushu University Graduate School of Pharmaceutical Sciences 3-1-1 Maidashi Higashi-ku Fukuoka 812-8582 Japan
    • Hiroyuki Miyata, Kyushu University Graduate School of Pharmaceutical Sciences 3-1-1 Maidashi Higashi-ku Fukuoka 812-8582 Japan
    • Kiyoshi Zaitsu, Kyushu University Graduate School of Pharmaceutical Sciences 3-1-1 Maidashi Higashi-ku Fukuoka 812-8582 Japan

Quelle: Journal of Fluorescence | 27 Jan 2010 | 9:33 pm CET

Fluorometric Study for the Reaction Between Sertraline and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole: Kinetics, Mechanism and Application for the Determination of Sertraline in Tablets

Abstract  
A fluorometric study has been carried out, for the first time, to investigate the reaction of the new generation antidepressant sertraline (SRT) with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl). In an alkaline buffered medium (pH 8.0), a green fluorescent product exhibiting maximum fluorescence intensity at 532 nm after excitation at 470 nm was produced. The factors affecting the reaction were carefully studied and the conditions were optimized. The kinetics of the reaction was investigated, the stoichiometry of the reaction was determined, and the mechanism was postulated. The activation energy of the reaction was determined and found to be 27.34 KJ mole-1. Under the optimum reaction conditions, a linear relationship with good correlation coefficient (r = 0.9998, n = 6) was found between the fluorescence intensity of the reaction product and SRT concentrations in the range of 0.3–20.0 µg ml-1. The limit of detection and limit of quantitation were 0.07 and 0.21 µg ml-1, respectively. The intra- and inter-assay precisions were satisfactory; the relative standard deviations did not exceed 2.61%. The proposed method was successfully applied to the determination of SRT in its pharmaceutical tablets with good accuracy; the recovery percentages were 96.97–102.23 ± 1.01–1.62%. The results were compared favorably with those of the reported method.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0595-3
  • Authors
    • Ashraf M. Mahmoud, Assiut University Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy Assiut 71256 Egypt
    • Ibrahim A. Darwish, King Saud University Department of Pharmaceutical Chemistry, College of Pharmacy P.O. Box 2457 Riyadh 11451 Saudi Arabia
    • Nasr Y. Khalil, King Saud University Department of Pharmaceutical Chemistry, College of Pharmacy P.O. Box 2457 Riyadh 11451 Saudi Arabia

Quelle: Journal of Fluorescence | 25 Jan 2010 | 5:59 pm CET

JoF Rejection Rate Exceeds 55%

JoF Rejection Rate Exceeds 55%

  • Content Type Journal Article
  • Category Editorial
  • DOI 10.1007/s10895-010-0599-z
  • Authors
    • Chris D. Geddes, The Institute of Fluorescence Baltimore USA

Quelle: Journal of Fluorescence | 19 Jan 2010 | 6:44 pm CET

Does Maternal Treatment with Zidovudine Affect Changes in Mandibles of Newborns? Laser Induced Fluorescence Study

Abstract  The influence of antiretroviral drug zidovudine treatment during pregnancy on mandible development in newborn rats was studied. The fluorescence of mandibles from 7-, 14- and 28-days old individuals was measured by means of fiber-optical fluorescence analyzer with 407 nm laser excitation. Obtained results revealed disturbing effect of maternal zidovudine administration on mandible fluorescence intensity which should decrease with bone development. Small changes in fluorescence of porphyrin forms are maintaining in the first month of newborns life while the changes observed in 440–585 nm range disappear.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0591-7
  • Authors
    • Zofia Krystyna Drzazga, University of Silesia Chełkowski’s Institute of Physics, Department of Medical Physics 40 007 Katowice ul. Uniwersytecka 4 Poland
    • Karina Maciejewska, University of Silesia Chełkowski’s Institute of Physics, Department of Medical Physics 40 007 Katowice ul. Uniwersytecka 4 Poland
    • Katarzyna Michalik, University of Silesia Chełkowski’s Institute of Physics, Department of Medical Physics 40 007 Katowice ul. Uniwersytecka 4 Poland
    • Michał Kaszuba, Institute of Stomatology 40-534 Katowice ul. Łabędzia 2 Poland
    • Barbara Nowińska, Medical University of Silesia Faculty of Pharmacy, Department of Pharmacology 41 200 Sosnowiec ul. Jagiellońska 4 Poland

Quelle: Journal of Fluorescence | 18 Jan 2010 | 7:48 pm CET

Study on the Intracellular Fate of Tat Peptide-Conjugated Quantum Dots by Spectroscopic Investigation

Abstract  
The photoluminescence (PL) spectrum of water-soluble thiol-capped CdTe quantum dots (QDs) conjugated with Tat peptide in solution showed a remarkable redshift as compared to that of unconjugated QDs. After cellular uptake of the Tat-QDs conjugates, the micro-PL spectrum of Tat-QDs in lysosomes showed a spectral blueshift, which was most probably due to the fact that Tat peptide was digested by the enzymes, leaving the Tat-detached QDs in lysosomes. The reasons for the spectral changes have been discussed in detail.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0579-3
  • Authors
    • Rongling Xiong, Fudan University Department of Optical Science and Engineering Shanghai 200433 China
    • Zheng Li, Fudan University Department of Optical Science and Engineering Shanghai 200433 China
    • Lan Mi, Fudan University Department of Optical Science and Engineering Shanghai 200433 China
    • Pei-Nan Wang, Fudan University Department of Optical Science and Engineering Shanghai 200433 China
    • Ji-Yao Chen, Fudan University Surface Physics Laboratory (National key laboratory), Department of Physics Shanghai 200433 China
    • Lixin Wang, Fudan University Department of Macromolecular Science and Key Laboratory of Molecular Engineering of Polymers Shanghai 200433 China
    • Wu-Li Yang, Fudan University Department of Macromolecular Science and Key Laboratory of Molecular Engineering of Polymers Shanghai 200433 China

Quelle: Journal of Fluorescence | 18 Jan 2010 | 7:48 pm CET

New Fluorescent Sensors Based on 1H-pyrazolo[3,4-b]quinoline Skeleton

Abstract  
Novel fluorescing dyes 1,3,4-triphenyl-6-(1,4,7,10-tetraoxa-13-aza-cyclopentadec-13-ylmethyl)-1H-pyrazolo[3,4-b]quinoline (K1) and 2-[(2-hydroxyethyl)-(1,3,4-triphenyl-1H-pyrazolo[3,4-b]quinolin-6-ylmethyl)-amino]ethanol (L1) have been synthesized and investigated by the means of steady state and time-resolved fluorescence techniques. These compounds act as sensors for the fluorescence detection of small inorganic cations (lithium, sodium, barium, magnesium and calcium) in solvents of different polarities (THF and acetonitrile). The mechanism, which allows application of these compounds as sensors, is an electron transfer from the electro-donative part of molecule to the acceptor part (fluorophore), which is retarded upon complexation of the electro-donative part by inorganic cations. We found that crown ether-containing compound is very sensitive to the addition of any investigated ions but amino alcohol-containing one exhibits better selectivity to the addition of two-valued cations. Two kinds of the complexes (LM+ and L2M+) were found in the investigated systems. In addition, the dyes may be used as fluorescence indicators in solvents of lower polarity like tetrahydrofuran.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0576-6
  • Authors
    • Marek Mac, Jagiellonian University Faculty of Chemistry Ingardena 3 30-060 Krakow Poland
    • Tomasz Uchacz, Jagiellonian University Faculty of Chemistry Ingardena 3 30-060 Krakow Poland
    • Tomasz Wróbel, Jagiellonian University Student of Faculty of Chemistry Krakow Poland
    • Andrzej Danel, University of Agriculture Department of Chemistry Balicka 122 31-149 Kraków Poland
    • Ewa Kulig, University of Agriculture Department of Chemistry Balicka 122 31-149 Kraków Poland

Quelle: Journal of Fluorescence | 18 Jan 2010 | 7:48 pm CET

Spectroscopic Properties and Laser Induced Fluorescence Determination of Some Endocrine Disrupting Compounds

Abstract  This work presents spectroscopic properties of some Endocrine Disrupting Compounds (EDCs), frequently found in food and in natural water. Studied molecules belong to the groups of phenolic and phthalate EDCs. In a first part, we have examined their absorption and fluorescence properties. Fluorescence emission wavelengths are about 300 nm for phenolic compounds and 360 nm for phtalate compounds; main excitation wavelengths being comprised between 210 nm and 230 nm. Fluorescence lifetimes measured are short (about 4 ns) and the fluorescence quantum yield has been determined. In a second part, to avoid the time consuming solvent extraction step, an analytical application to evaluate the performance of a direct analysis by laser induced fluorescence spectroscopy of ECDs traces in tap water and in raw water is presented. Good detection limits have been obtained, i.e.: 0.35 µg.L−1 of chlorophenol in tap water, which are always lower than the reported Predictive Non Efficient Concentration (PNEC).

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0583-7
  • Authors
    • Badr Benmansour, Université Européenne de Bretagne Brest University, UMR CNRS 6521 CEMCA 6 av. Le Gorgeu 29285 Brest cedex 3 France
    • Ludovic Stephan, Université Européenne de Bretagne Brest University, UMR CNRS 6521 CEMCA 6 av. Le Gorgeu 29285 Brest cedex 3 France
    • Jean-Yves Cabon, Université Européenne de Bretagne Brest University, UMR CNRS 6521 CEMCA 6 av. Le Gorgeu 29285 Brest cedex 3 France
    • Laure Deschamps, Université Européenne de Bretagne Brest University, UMR CNRS 6521 CEMCA 6 av. Le Gorgeu 29285 Brest cedex 3 France
    • Philippe Giamarchi, Université Européenne de Bretagne Brest University, UMR CNRS 6521 CEMCA 6 av. Le Gorgeu 29285 Brest cedex 3 France

Quelle: Journal of Fluorescence | 18 Jan 2010 | 7:48 pm CET

The Role of Pyranine in Characterization of PAAm-κC Composites by Using Fluorescence Technique

Abstract  Polyacrylamide (PAAm) doped by κ-carrageenan (κC) gels were prepared with various amounts of κC varying in the range between 0 wt.% and 3 wt.%. Steady-state fluorescence (SSF) technique was employed for studying sol-gel transition and swelling of PAAm-κC composite gels which were prepared by free-radical crosslinking copolymerization. Pyranine was introduced as a fluorescence probe. Pyranine molecules start to bind to acrylamide polymer chains upon the initiation of the polymerization, thus the spectra of the bonded pyranines shift to the shorter wavelengths. Fluorescence spectra from the bonded pyranines allow one to monitor the sol-gel transition and to test the universality of the sol-gel transition as a function of some kinetic parameters like polymer concentration. Observations around the gel point, t c for PAAm-κC composite gels showed that the gel fraction exponent β obeyed the percolation result for low κC (<2.0 wt. %) however classical results were produced at higher κC (>2.0 wt.%). On the other hand, fluorescence intensity of pyranine was measured during in situ swelling process at various amounts of κC and it was observed that fluorescence intensity values decreased as swelling is proceeded. Li-Tanaka equation was used to determine the swelling time constants, τ and cooperative diffusion coefficients, D.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0588-2
  • Authors
    • Gülşen Akin Evingur, Istanbul Technical University Faculty of Science and Letters, Physics Department 34469 Maslak- Istanbul Turkey
    • Önder Pekcan, Kadir Has University 34320 Cibali- Istanbul Turkey

Quelle: Journal of Fluorescence | 18 Jan 2010 | 7:48 pm CET

Fluorescence Lymph Node Mapping in Living Mice Using Quantum Dots and a Compression Technique

Abstract  
The lymphatic system is essential in oncology and immunology, and in vivo fluorescence imaging plays a major role in assessing the lymphatic drainage. We investigated non–invasive fluorescence lymph node mapping in mice with special reference to the assessment of deep abdominal lymph nodes. Quantum dots were injected subcutaneously into the rear footpads of mice, and the time course of the fluorescent signal was assessed. Visualization of abdominal lymph nodes was compared with and without compression of the abdomen with transparent, colorless tape at injection doses of 1, 5, and 20 pmol. Popliteal, sacral, iliac, and renal lymph nodes were delineated by non–invasive imaging. Lymph node signals increased up to 3 h after injection. Compression of the abdomen markedly improved the visualization of the iliac nodes, which were invisible at 5 pmol without compression and visible at 1 pmol with compression. Fluorescence lymph node mapping using quantum dots allowed the visualization of deep abdominal lymph nodes in addition to superficial nodes in intact mice, with the aid of a simple compression technique.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0593-5
  • Authors
    • Yusuke Inoue, University of Tokyo Department of Radiology, Institute of Medical Science 4-6-1 Shirokanedai Minato-ku Tokyo 108-8639 Japan
    • Shigeru Kiryu, University of Tokyo Department of Radiology, Institute of Medical Science 4-6-1 Shirokanedai Minato-ku Tokyo 108-8639 Japan
    • Makoto Watanabe, University of Tokyo Department of Radiology, Institute of Medical Science 4-6-1 Shirokanedai Minato-ku Tokyo 108-8639 Japan
    • Naoki Oyaizu, University of Tokyo Department of Laboratory Medicine, Institute of Medical Science Tokyo Japan
    • Kuni Ohtomo, University of Tokyo Department of Radiology, Graduate School of Medicine Tokyo Japan

Quelle: Journal of Fluorescence | 15 Jan 2010 | 7:01 pm CET

Fluorescence Spectroscopy as Tool for Bone Development Monitoring in Newborn Rats

Abstract  Autofluorescence of the mandible and femur bones taken from newborn rats (7-, 14- and 28-day old) was studied. Endogenous fluorophores were excited with 231 nm, 291 nm, 340 nm and 360 nm wavelengths. Modifications in content and microenvironment of both noncolagenous and collagenous constituents of bone tissue as well as metabolic coenzymes during the bone formation with age were reflected in fluorescence emission spectra. The increase of emission from peptide bonds and tryptophan residues was noted with rat age while for collagen and metabolic coenzymes at the first 2 weeks only. After maternal administration of indinavir the changes in fluorescence intensity and shifts in position of peak maximum were found. The distinct drop of emission from peptide bonds and tryptophan residues in studied bones was detected. In the case of collagen and metabolic coenzymes the red shift of peak maximum was revealed. Fluorescence spectroscopy could be used to follow bone development in newborn rats and effect of maternal indinavir administration on offspring.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0584-6
  • Authors
    • Zofia Krystyna Drzazga, University of Silesia A. Chełkowski’ Institute of Physics, Department of Medical Physics Uniwersytecka 4 40-007 Katowice Poland
    • Aneta Kluczewska-Gałka, University of Silesia A. Chełkowski’ Institute of Physics, Department of Medical Physics Uniwersytecka 4 40-007 Katowice Poland
    • Anna Michnik, University of Silesia A. Chełkowski’ Institute of Physics, Department of Medical Physics Uniwersytecka 4 40-007 Katowice Poland
    • Michał Kaszuba, Institute of Stomatology Łabędzia 2 40-534 Katowice Poland
    • Hanna Trzeciak, Medical University of Silesia Department of Prosthetic Dentistry pl. Akademicki 17 41-902 Bytom Poland

Quelle: Journal of Fluorescence | 12 Jan 2010 | 7:20 pm CET

Determinations of Uranium(VI) Binding Properties with some Metalloproteins (Transferrin, Albumin, Metallothionein and Ferritin) by Fluorescence Quenching

Abstract  
The interactions between uranium and four metalloproteins (Apo-HTf, HSA, MT and Apo-EqSF) were investigated using fluorescence quenching measurements. The combined use of a microplate spectrofluorometer and logarithmic additions of uranium into protein solutions allowed us to define the fluorescence quenching over a wide range of [U]/[Pi] ratios (from 0.05 to 1150) at physiologically relevant conditions of pH. Results showed that fluorescence from the four metalloproteins was quenched by UO22+. Stoichiometry reactions, fluorescence quenching mechanisms and complexing properties of metalloproteins, i.e. binding constants and binding sites densities, were determined using classic fluorescence quenching methods and curve-fitting software (PROSECE). It was demonstrated that in our test conditions, the metalloprotein complexation by uranium could be simulated by two specific sites (L1 and L2). Results showed that the U(VI)–Apo-HTf complexation constant values (log K1 = 7.7, log K2 = 4.6) were slightly higher than those observed for U(VI)–HSA complex (log K1 = 6.1, log K2 = 4.8), U(VI)–MT complex (log K1 = 6.5, log K2 = 5.6) and U(VI)–Apo-EqsF complex (log K1 = 5.3, log K2 = 3.9). PROSECE fitting studies also showed that the complexing capacities of each protein were different: 550 moles of U(VI) are complexed by Apo-EqSF while only 28, 10 and 5 moles of U(VI) are complexed by Apo-HTf, HSA and MT, respectively.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0587-3
  • Authors
    • Jérôme Michon, Institut de Radioprotection et Sûreté Nucléaire Laboratoire de Radioécologie et Ecotoxicologie Cadarache, Bât 186, BP3 13115 Saint-Paul-lez-Durance Cedex France
    • Sandrine Frelon, Institut de Radioprotection et Sûreté Nucléaire Laboratoire de Radioécologie et Ecotoxicologie Cadarache, Bât 186, BP3 13115 Saint-Paul-lez-Durance Cedex France
    • Cédric Garnier, Université Bordeaux I Groupe de Physico Toxico Chimie des Systèmes Naturels, Institut des Sciences Moléculaires, (ISM–UMR CNRS 5255) 33405 Talence Cedex France
    • Frédéric Coppin, Institut de Radioprotection et Sûreté Nucléaire Laboratoire de Radioécologie et Ecotoxicologie Cadarache, Bât 186, BP3 13115 Saint-Paul-lez-Durance Cedex France

Quelle: Journal of Fluorescence | 11 Jan 2010 | 7:22 pm CET

Maximum Entropy Analysis of Analytically Simulated Complex Fluorescence Decays

Abstract  We tested a Maximum Entropy Method developed for oversampled data (SVD-MEM) on complex analytically simulated exponential decay data consisting of both noisy and noiseless multi-exponential fluorescence decay curves. We observed recovery of simulated parameters for three sets of data: a decay containing three exponential functions in both intensity and anisotropy curves, a set of intensity decays composed of 4, 5 and 6 exponential functions, and a decay characterized by a Gaussian lifetime distribution. The SVD-MEM fitting of the noiseless data returned the simulated parameters with the high accuracy. Noise added to the data affected recovery of the parameters in dependence on a data complexity. At selected realistic noise levels we obtained a good recovery of simulated parameters for all tested data sets. Decay parameters recovered from decays containing discrete lifetime components were almost independent of the value of the entropy scaling parameter γ used in the maximization procedure when it changed across the main peak of its posterior probability. A correct recovery of the Gaussian shaped lifetime distribution required selection of the γ-factor which was by several orders of magnitude larger than its most probable value to avoid a band splitting.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0589-1
  • Authors
    • Jaroslav Vecer, Charles University Faculty of Mathematics and Physics, Institute of Physics Ke Karlovu 5 121 16 Prague 2 Czech Republic
    • Petr Herman, Charles University Faculty of Mathematics and Physics, Institute of Physics Ke Karlovu 5 121 16 Prague 2 Czech Republic

Quelle: Journal of Fluorescence | 11 Jan 2010 | 7:22 pm CET

Reductive Fluorescence Quenching of the Photoexcited Free Base meso-Tetrakis (Pentafluorophenyl) Porphyrin by Amines

Abstract  
Steady state and time resolved fluorescence quenching behaviors of meso-Tetrakis (pentafluorophenyl) porphyrin (H2F20TPP) in presence of different aliphatic and aromatic amines have been executed in homogeneous dichloromethane (DCM) solution. At room temperature in DCM, free base (H2F20TPP) shows fluorescence with two distinct peaks at 640 and 711 nm and natural lifetime τ f = 9.8 ns which are very similar to that of meso-tetraphenyl porphyrin (TPP). Unlike TPP, addition of both aliphatic and aromatic amines to a solution containing H2F20TPP results in an efficient decrease in fluorescence intensity without altering the shape and peak position of fluorescence emission. Upon addition of amines there was no change in optical absorption spectra of H2F20TPP. The fluorescence quenching rate constants ranged from 1 × 109 to 4 × 109 s−1, which are one order below to the diffusion control limit, and temperature dependent quenching rate constants yield the activation energies which are found to be order of 0.1 eV. Femto second transient absorption studies reveal the existence of amine cation radical and porphyrin anion radicals with very short decay time (15 ps). The fluorescence quenching reaction follows Stern–Volmer kinetics. Steady state and time-resolved data are interpreted within general kinetic scheme of Marcus semi-classical model which attributes bimolecular electron transfer process between amines and the lowest excited singlet state of H2F20TPP. Calculated internal reorganization energies are found to be in between 0.04 and 0.22 ev. Variation of electron transfer rate as function of free energy change (∆G0) points the ET reactions in the present systems are in Marcus normal region. This is the first example of reductive fluorescence quenching of free base neutral porphyrins in homogeneous organic solvent ever known.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0582-8
  • Authors
    • Suthari Prashanthi, Indian Institute of Chemical Technology Inorganic and Physical Chemistry Division Institution Uppal Road, Tarnaka Hyderabad 500607 India
    • P. Hemant Kumar, Indian Institute of Chemical Technology Inorganic and Physical Chemistry Division Institution Uppal Road, Tarnaka Hyderabad 500607 India
    • Li Wang, Kwansei Gakuin University Department of Chemistry, School of Science 2-1 Gakuen Sanda 669-1337 Japan
    • Arun Kumar Perepogu, Indian Institute of Chemical Technology Organic Chemistry Division-II Uppal Road, Tarnaka Hyderabad 500607 India
    • Prakriti Ranjan Bangal, Indian Institute of Chemical Technology Inorganic and Physical Chemistry Division Institution Uppal Road, Tarnaka Hyderabad 500607 India

Quelle: Journal of Fluorescence | 8 Jan 2010 | 10:40 pm CET

Glycosylated Quantum Dots for the Selective Labelling of Kluyveromyces bulgaricus and Saccharomyces cerevisiae Yeast Strains

Abstract  
Highly fluorescent CdTe quantum dots (QDs) stabilized by thioglycolic acid (TGA) were prepared by an aqueous solution approach and used as fluorescent labels in detecting yeast cells. Sugars (mannose, galactose or glucose) were adsorbed on CdTe@TGA QDs and the interaction of these nanoparticles with yeast cells was studied by fluorescence microscopy. Results obtained demonstrate that galactose and mannose functionalized QDs associate respectively with Kluyveromyces bulgaricus and Saccharomyces cerevisiae yeast strains due to saccharide/lectin specific recognition. Glucose-functionalized CdTe QDs, which are not recognized by cell lectins, preferentially localize in the bud scars of S. cerevisiae.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0590-8
  • Authors
    • Joël Coulon, Nancy-University, CNRS LCPME, Laboratoire de Chimie Physique et Microbiologie pour l’Environnement 405 rue de Vandoeuvre 54600 Villers-lès-Nancy France
    • Ilan Thouvenin, Nancy-University, CNRS LCPME, Laboratoire de Chimie Physique et Microbiologie pour l’Environnement 405 rue de Vandoeuvre 54600 Villers-lès-Nancy France
    • Fadi Aldeek, Nancy-University, CNRS LCPME, Laboratoire de Chimie Physique et Microbiologie pour l’Environnement 405 rue de Vandoeuvre 54600 Villers-lès-Nancy France
    • Lavinia Balan, Université de Haute Alsace, ENSCMu DPG, Département de Photochimie Générale, UMR CNRS 7525 3 rue Alfred Werner 68093 Mulhouse France
    • Raphaël Schneider, Nancy-University, CNRS DCPR, Département de Chimie Physique de Réactions 1 rue Grandville BP 20451 54001 Nancy France

Quelle: Journal of Fluorescence | 7 Jan 2010 | 11:22 pm CET

Enantioselective Fluorescent Sensors for Amino Acid Derivatives Based on BINOL Bearing S-tryptophan Unit: Synthesis and Chiral Recognition

Abstract  Four novel derivatives of BINOL bearing S-tryptophan unit have been prepared and the structures of these compounds characterized by IR, MS, 1H and 13C NMR spectroscopy and elemental analysis. The enantioselective recognition of these receptors has been studied by fluorescence titration and 1H NMR spectroscopy. The receptors exhibited different chiral recognition abilities towards N-Boc-protected amino acid anions and formed 1:1 complexes between host and guest. Receptors exhibit excellent enantioselective fluorescent recognition ability towards the amino acid derivatives.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0585-5
  • Authors
    • Kuo-Xi Xu, Henan University Institute of Fine Chemistry and Chemical Engineering Kaifeng 475004 China
    • Peng-Fei Cheng, Henan University Key Lab of Natural Medicinal and Immunal Engineering Kaifeng 475004 China
    • Jin Zhao, Henan University Key Lab of Natural Medicinal and Immunal Engineering Kaifeng 475004 China
    • Chao-Jie Wang, Henan University Key Lab of Natural Medicinal and Immunal Engineering Kaifeng 475004 China

Quelle: Journal of Fluorescence | 6 Jan 2010 | 7:06 pm CET

Fluorescence Lifetime Tuning—A Novel Approach to Study Flip-Flop Kinetics in Supported Phospholipid Bilayers

Abstract  
In the present work we introduce a straightforward fluorescent assay that can be applied in studies of the transbilayer movement (flip-flop) of fluorescent lipid analogues across supported phospholipid bilayers (SPBs). The assay is based on the distance dependent fluorescence quenching by light absorbing surfaces. Applied to SPBs this effect leads to strong differences in fluorescence lifetimes when the dye moves from the outer lipid leaflet to the leaflet in contact with the support. Herein, we present the basic principles of this novel approach, and comment on its advantages over the commonly used methods for investigating flip-flop dynamics across lipid bilayers. We test the assay on the fluorescent lipid analog Atto633-DOPE and the 3-hydroxyflavone F2N12S probe in SPBs composed of DOPC/ DOPS lipids. Moreover, we compare and discuss the flip-flop rates of the probes with respect to their lateral diffusion coefficients.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0581-9
  • Authors
    • Anna Kułakowska, Academy of Sciences of the Czech Republic J. Heyrovsky Institute of Physical Chemistry v. v. i., Dolejskova 3 18223 Prague 8 Czech Republic
    • Piotr Jurkiewicz, Academy of Sciences of the Czech Republic J. Heyrovsky Institute of Physical Chemistry v. v. i., Dolejskova 3 18223 Prague 8 Czech Republic
    • Jan Sýkora, Academy of Sciences of the Czech Republic J. Heyrovsky Institute of Physical Chemistry v. v. i., Dolejskova 3 18223 Prague 8 Czech Republic
    • Aleš Benda, Academy of Sciences of the Czech Republic J. Heyrovsky Institute of Physical Chemistry v. v. i., Dolejskova 3 18223 Prague 8 Czech Republic
    • Yves Mely, Université de Strasbourg Laboratoire Biophotonique et Pharmacologie, UMR 7213 CNRS, Faculté de Pharmacie 74, Route du Rhin 67401 Illkirch Cedex France
    • Martin Hof, Academy of Sciences of the Czech Republic J. Heyrovsky Institute of Physical Chemistry v. v. i., Dolejskova 3 18223 Prague 8 Czech Republic

Quelle: Journal of Fluorescence | 28 Dec 2009 | 8:26 pm CET

Studies on the Interactions of 2, 4-Dinitrophenol and 2, 4-Dichlorphenol with Trypsin

Abstract  
The interactions of 2, 4-dinitrophenol and 2, 4-dichlorphenol with trypsin were investigated by fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. The 2, 4-dinitrophenol and 2, 4-dichlorphenol effectively quenched the intrinsic fluorescence of trypsin via static quenching. The process of binding 2, 4-dinitrophenol and 2, 4-dichlorphenol with trypsin was a spontaneous molecular interaction procedure. The electrostatic repulsion does favor the interaction between 2, 4-DNP and trypsin. However, the interaction of 2, 4-DCP and trypsin can be explained on the basis of hydrogen bonding and van der Waals. The results of synchronous fluorescence spectroscopy and three-dimensional fluorescence spectra indicated that the structure of these trytophan and tyrosine residues environments were altered by 2, 4-DNP and 2, 4-DCP.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0574-8
  • Authors
    • Hong-Mei Zhang, Yancheng Teachers University Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, Institute of Applied Chemistry and Environmental Engineering Yancheng City Jiangsu Province 224002 People’s Republic of China
    • Qiu-Hua Zhou, Yancheng Teachers University Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, Institute of Applied Chemistry and Environmental Engineering Yancheng City Jiangsu Province 224002 People’s Republic of China
    • Yan-Qing Wang, Yancheng Teachers University Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, Institute of Applied Chemistry and Environmental Engineering Yancheng City Jiangsu Province 224002 People’s Republic of China

Quelle: Journal of Fluorescence | 23 Dec 2009 | 11:54 pm CET

Determination of the β-Glucosidase Activity in Different Soils by Pre Capillary Enzyme Assay Using Capillary Electrophoresis with Laser-Induced Fluorescence Detection

Abstract  
Enzyme activities can provide indication for quantitative changes in soil organic matter (SOM). It is known that the activities of most enzymes increase as native SOM content reflecting larger microbial communities and stabilization of enzymes on humic materials. β-Gucosidase (β-Glu) activities have been frequently used as indicators of changes in quantity and quality of SOM. In this study we propose a simple and very sensitive method, which has lower limit of detection compared with classic spectrophotometric method with the aim of determinate the β-Glu activity in soil samples using Fluorescein mono-β-D-glucopyranoside (FMGlc) as a substrate. The fluorescein released by the enzymatic reaction was quantified by capillary electrophoresis-laser induced fluorescence (CE-LIF) method. The background electrolyte (BGE) consisted in 40 mM phosphate buffer, pH 6. The LOD and LOQ for fluorescein were 1.3 10−7 mg mL−1 and 6.4 10−6 mg mL−1, respectively. This work deals with the minimization of the mixture for the enzymatic reaction and with the optimization conditions of CE separation. To the best of our knowledge, this is the first time that an enzymatic activity was detected in soil using CE-LIF system.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0575-7
  • Authors
    • Patricia W. Stege, National University of San Luis, CONICET INQUISAL, Department of Chemistry Chacabuco y Pedernera D5700BWS San Luis Argentina
    • Germán A. Messina, National University of San Luis, CONICET INQUISAL, Department of Chemistry Chacabuco y Pedernera D5700BWS San Luis Argentina
    • Guillermo Bianchi, Los Andes University Science Faculty, Department of Chemistry Mérida Venezuela
    • Roberto A. Olsina, National University of San Luis, CONICET INQUISAL, Department of Chemistry Chacabuco y Pedernera D5700BWS San Luis Argentina

Quelle: Journal of Fluorescence | 22 Dec 2009 | 12:02 am CET

A New Fluorescent Chemosensor Detecting Co2+ and K+ in DMF Buffered Solution

Abstract  
A new fluorescent chemosensor 2-(2-thiophene)imidazo [4,5,f]-1,10-phenanthroline (L) was prepared and characterized. By adding univalent or divalent metal ions such as Na+, K+, Mg2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Ag+, Zn2+, Cd2+ and Hg2+ ions into the solution of L in DMF under buffered conditions with the working pH ranging from 7.0 to 8.0, we found that L could be used to detect K+ ratiometricly and it could also be applied to sense Co2+ with the phenomenon of fluorescence quenching of L. While the response behavior of L was not discernibly affected by other examined metal ions.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0580-x
  • Authors
    • Xiuli Wang, Bohai University Faculty of Chemistry and Chemical Engineering, Liaoning Key Laboratory of Applied Chemistry Jinzhou 121000 People’s Republic of China
    • Wenyan Zheng, Bohai University Faculty of Chemistry and Chemical Engineering, Liaoning Key Laboratory of Applied Chemistry Jinzhou 121000 People’s Republic of China
    • Hongyan Lin, Bohai University Faculty of Chemistry and Chemical Engineering, Liaoning Key Laboratory of Applied Chemistry Jinzhou 121000 People’s Republic of China
    • Guocheng Liu, Bohai University Faculty of Chemistry and Chemical Engineering, Liaoning Key Laboratory of Applied Chemistry Jinzhou 121000 People’s Republic of China

Quelle: Journal of Fluorescence | 18 Dec 2009 | 8:12 am CET

A Novel Fluorescent Silver Ion Biosensor Based on Nucleic Acid Molecular “Light Switch”

Abstract  
As one of nucleic acid molecular “light switch”, Ru(bipy)2(dppx)2+ is a good probe for the determination of double-helical DNA, which displays intense fluorescence when double-helical DNA is present. However, the fluorescence of Ru(bipy)2(dppx)2+ is quenched when Ag+ is added to the Ru(bipy)2(dppx)2+-DNA system. Based on the quenching of the fluorescence of Ru(bipy)2(dppx)2+-DNA system by Ag+, a simple, rapid and specific method for Ag+ determination was proposed. In the optimum conditions, Ag+ concentration versus Ru(bipy)2(dppx)2+ fluorescence intensity gave a linear response in the range from 0.2 to 6.0 μM with a detection limit (3σ) of 3.2 × 10−8 M. The proposed method has been applied to determine the Ag+ in water samples and sulfadiazine silver cream successfully. Because of the intense fluorescence of Ru(bipy)2dppx2+ when DNA is present, the interaction between Ag+ and DNA was confirmed by fluorescence microscopy and the phenomenon of the fluorescence images agreed well with the results. The possible mechanism of the reaction was also discussed by circular dichroism spectra and isothermal titration calorimetry.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0578-4
  • Authors
    • Qi Xiao, Wuhan University Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences Wuhan 430072 People’s Republic of China
    • Shan Huang, Wuhan University Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences Wuhan 430072 People’s Republic of China
    • Yushu Ge, Wuhan University Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences Wuhan 430072 People’s Republic of China
    • Zhike He, Wuhan University Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences Wuhan 430072 People’s Republic of China
    • Yi Liu, Wuhan University Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences Wuhan 430072 People’s Republic of China
    • Jiangong Liang, Huazhong Agricultural University College of Science Wuhan 430070 People’s Republic of China

Quelle: Journal of Fluorescence | 17 Dec 2009 | 8:05 am CET

A Long Wavelength Excitable Fluorophore; Chloro Phenyl Imino Propenyl Aniline (CPIPA) for Selective Sensing of Hg (II)

Abstract  
In this study, a very sensitive and highly selective irreversible optical chemical sensor (optode) for mercury ions was described. The sensing scheme was based on the interaction of Hg (II) with a newly synthesized fluoroionophore; chloro phenyl imino propenyl aniline (CPIPA) in plasticized PVC membrane. The sensor membranes were tested for the determination of mercury ion in aqueous solutions by batch and flow-through methods. The optodes allow determination of Hg (II) in the working range of 1.0 × 10−9–1.0 × 10−5 M with a detection limit of 4.3 ppb. The sensor exhibited excellent selectivity for Hg (II) with respect to several common alkali, alkaline earth and transition metal ions. The association constant of the 1:1 complex formation for Hg (II) was found to be Ka = 1.86 × 105 M−1. The CPIPA exhibited high fluorescence quantum yield, long excitation and emission wavelength and high Stokes’ shift values in the solid matrix which makes it compatible with solid state optics.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0577-5
  • Authors
    • Kadriye Ertekin, University of Dokuz Eylul Faculty of Arts and Sciences, Department of Chemistry 35160 Tinaztepe Izmir Turkey
    • Ozlem Oter, University of Dokuz Eylul Faculty of Arts and Sciences, Department of Chemistry 35160 Tinaztepe Izmir Turkey
    • Mustafa Ture, University of Dokuz Eylul Faculty of Arts and Sciences, Department of Chemistry 35160 Tinaztepe Izmir Turkey
    • Serpil Denizalti, University of Ege Faculty of Sciences, Department of Chemistry 35100 Bornova Izmir Turkey
    • Engin Cetinkaya, University of Ege Faculty of Sciences, Department of Chemistry 35100 Bornova Izmir Turkey

Quelle: Journal of Fluorescence | 17 Dec 2009 | 8:05 am CET

Magnetic Fluorescent Composite Nanoparticles for the Fluoroimmunoassays of Newcastle Disease Virus and Avian Virus Arthritis Virus

Abstract  
A new detection format for multiplexed analysis based on the use of magnetic fluorescent composite nanoparticles was presented in this paper. Two different antigens, Newcastle disease virus (NDV) antigen and Avian virus arthritis virus (AVAV) antigen, were conjugated to two kinds of magnetic fluorescent composite nanoparticles of different luminescent colors, while red-emitting CdTe QDs were attached to the antibody of NDV and AVAV. Both CdTe QDs-labeled antibodies and magnetic fluorescent composite nanoparticles labeled antigens were used to form a typical immunoreaction system for the detection of NDV and AVAV. Also a typical mixed separation format was realized, which showed the outstanding magnetic properties of composite nanoparticles and the broad application in immunoseparation.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0573-9
  • Authors
    • Guannan Wang, Jilin University Department of Analytical Chemistry, College of Chemistry Changchun 130012 China
    • Ping Xie, Jilin Entry-Exit Inspection and Quarantine Bureau Changchun China
    • Chengrui Xiao, Jilin Entry-Exit Inspection and Quarantine Bureau Changchun China
    • Pingfan Yuan, Jilin University Department of Analytical Chemistry, College of Chemistry Changchun 130012 China
    • Xingguang Su, Jilin University Department of Analytical Chemistry, College of Chemistry Changchun 130012 China

Quelle: Journal of Fluorescence | 8 Dec 2009 | 8:48 pm CET

Fluorescence Quenching to Study Protein-ligand Binding: Common Errors

Abstract  
A number of recent articles, amongst others several published in the Journal of Fluorescence, use inappropriate fluorescence methodology to determine ligand binding characteristics to (mostly) proteins. In this Letter, several common pitfalls are discussed in relation to two recent publications in the Journal of Fluorescence (Wang et al. (2009) 19:801–808; Ding et al. (2009) 19:783–791). The Author hopes that this contribution helps to prevent a further spread of the incorrect methodology, and results in a reappraisal of those articles already published using similar methodology.

  • Content Type Journal Article
  • Category Short Communication
  • DOI 10.1007/s10895-009-0572-x
  • Authors
    • Marco van de Weert, University of Copenhagen Department of Pharmaceutics and Analytical Chemistry, Faculty of Pharmaceutical Sciences Universitetsparken 2 DK-2100 Copenhagen Denmark

Quelle: Journal of Fluorescence | 8 Dec 2009 | 8:48 pm CET

Long Wavelength Fluorescence Lifetime Standards for Front-Face Fluorometry

Abstract  
With the increased development and use of fluorescence lifetime-based sensors, fiber optic sensors, fluorescence lifetime imaging microscopy (FLIM), and plate and array readers, , calibration standards are essential to ensure the proper function of these devices and accurate results. For many devices that utilize a “front face excitation” geometry where the excitation is nearly coaxial with the direction of emission, scattering-based lifetime standards are problematic and fluorescent lifetime standards are necessary. As more long wavelength (red and near-infrared) fluorophores are used to avoid background autofluorescence, the lack of lifetime standards in this wavelength range has only become more apparent . We describe an approach to developing lifetime standards in any wavelength range, based on Förster resonance energy transfer (FRET). These standards are bright, highly reproducible, have a broad decrease in observed lifetime, and an emission wavelength in the red to near infrared making them well suited for the laboratory and field applications as well. This basic approach can be extended to produce lifetime standards for other wavelength regimes.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0565-9
  • Authors
    • Bryan J. McCranor, University of Maryland School of Medicine Department of Biochemistry and Molecular Biology 108 N. Greene Street Baltimore MD 21201-1503 USA
    • Richard B. Thompson, University of Maryland School of Medicine Department of Biochemistry and Molecular Biology 108 N. Greene Street Baltimore MD 21201-1503 USA

Quelle: Journal of Fluorescence | 1 Dec 2009 | 10:02 pm CET

Efficiently Tuning the Absorption and Fluorescence Spectroscopy of the Novel Branched p-Nitro-stilbene Derivatives with Chemical Strategy

Abstract  Suitable chemical strategy is a useful approach on the tuning color and photoluminescence of organic dyes. This paper presented tuning novel branched p-nitro-stilbene derivatives efficiently with a new chemical strategy through variation of chemical bridged bond. Linking bonds played significant effects on the absorption and fluorescence spectroscopy of the branched p-nitro-stilbene derivatives. A change from “D-π-A” to “A-π-A” chemical structural characteristics occurred for the branched p-nitro-stilbene derivatives as ester bond was attached. This led to not only large hypsochromic shift of the maximal absorption wavelength of the branched p-nitro-stilbene derivatives, but considerable reduction of the fluorescence intensity. While in contrast, the branched p-nitro-stilbene derivatives with ether bond exhibited longer wavelength absorption and much stronger fluorescence emission in modest polar solvent. The cyclic voltammograms of these branched p-nitro-stilbene derivatives were determined. Different electrochemistry processes were observed for the branched p-nitro-stilbene derivatives with various linking bonds. The energies of frontier orbital of the branched p-nitro-stilbene derivatives were estimated from their corresponding redox potentials. Molecular geometry optimization of the branched p-nitro-stilbene derivatives was performed, and the electron density distribution of frontier orbital was analyzed. Thermal stabilities of these branched nitro-stilbene derivatives were investigated via the analysis of the differential scanning calorimetry (DSC) and thermograving (TGA) curves. This paper presented strong evidences that the absorption and fluorescence spectroscopy of the branched stilbene derivatives could be mediated efficiently by chemical strategy.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0564-x
  • Authors
    • Fang Gao, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China
    • Liufeng Yang, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China
    • Long Yang, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China
    • Hongru Li, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China
    • Shengtao Zhang, Chongqing University College of Chemistry and Chemical Engineering Chongqing 400044 China

Quelle: Journal of Fluorescence | 1 Dec 2009 | 10:02 pm CET

Validated Spectrofluorimetric Method for the Determination of Lamotrigine in Tablets and Human Plasma Through Derivatization with o-phthalaldehyde

Abstract  
A sensitive, simple and selective spectrofluorimetric method was developed for the determination of Lamotrigine (LMT) in pharmaceutical formulations and biological fluids. The method is based on reaction of LMT with o-phthalaldehyde in presence of 2-mercaptoethanol in borate buffer of pH 9.8 to yield a highly fluorescent derivative that is measured at 448 nm after excitation at 337 nm. The different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence-concentration plot was rectilinear over the range of 0.1–1.0 µg ml−1 with lower limit of detection (LOD) 0.02 μg ml−1 and limit of quantification (LOQ) 0.06 μg ml−1 respectively. The proposed method was successfully applied to the the analysis of commercial tablets. Statistical comparison of the results obtained by the proposed and reference method revealed no significant difference in the performance of the two methods regarding the accuracy and precision respectively. The proposed method was further extended to the in-vitro and in-vivo determination of the drug in spiked and real human plasma. The mean percentage recoveries in spiked and real human plasma (n = 3) were 95.78 ± 1.37 and 90.93 ± 2.34 respectively. Interference arising from co-administered drugs was also studied. A proposal for the reaction pathway with o-phthalaldehyde was postulated.

  • Content Type Journal Article
  • Category Original Paper
  • DOI 10.1007/s10895-009-0568-6
  • Authors
    • Nahed M. El-Enany, Mansoura University Department of Analytical Chemistry Mansoura 35516 Egypt
    • Dina T. El-Sherbiny, Mansoura University Department of Medicinal Chemistry Mansoura 35516 Egypt
    • Amina A. Abdelal, Mansoura University Department of Analytical Chemistry Mansoura 35516 Egypt
    • Fathalla F. Belal, Mansoura University Department of Analytical Chemistry Mansoura 35516 Egypt

Quelle: Journal of Fluorescence | 27 Nov 2009 | 8:05 am CET




 


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