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Fluorescence Properties (fluorescence + property)
Kinds of Fluorescence Properties Selected AbstractsConstruction of 1D and 2D Copper(I) Coordination Polymers Assembled by PhS(CH2)nSPh (n = 1, 2) Dithioether Ligands: Surprising Effect of the Spacer Length on the Dimensionality, Cluster Nuclearity and the Fluorescence Properties of the Metal,Organic Framework,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2007Harmel N. Peindy Abstract Treatment of CuI with PhSCH2SPh in MeCN solution affords, by a self-assembly reaction, the monodimensional metal,organic coordination polymer [Cu4I4{,-PhS2CH2SPh}2]n (1), in which Cu4(,3 -I)4 cluster units are linked by the dithioether ligand in a 1D necklace structure. In contrast, the reaction of PhSCH2CH2SPh with CuI results in the formation of the metallopolymer [(CuI)2{,-PhS(CH2)2SPh}2]n (2). The 2D network of 2 is built from dimeric Cu2I2 units which are connected by 1,2-bis(phenylthio)ethane bridging ligands. The solid-state luminescence spectrum of 1 exhibits a strong emission around 532 nm, whereas a weak emission centred at 413 nm is observed in the case of 2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Novel Cadmium(II) Adipate Coordination Polymers with Structural Transformation via Oxalate Ligand: Syntheses, Structures and Fluorescence PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2004Na Hao Abstract Two novel cadmium adipate coordination polymers [Cd{O2C(CH2)4CO2}{1,10-phen}]n (1) and [Cd2(C2O4){O2C(CH2)4CO2(OH2)2}{2,2,-bipy}]·H2O (2) [adipic acid = HO2C(CH2)4CO2H] have been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. Crystallographic data for 1: monoclinic, C2/c, a = 16.186(3) Å, b = 15.487(3) Å, c = 14.052(3) Å, , = 112.73(3)°, Z = 8. Crystal data for 2: monoclinic, Cc, a = 23.448(5) Å, b = 11.826(2) Å, c = 8.3163(17) Å, , = 99.08(3)°, Z = 4. The structural analysis reveals that 1 forms a novel one-dimensional chain in which the binuclear Cd centers are linked by adipate anions. Compound 2 is the first example in which both a 2,2,-bipy ligand and an oxalate group are found in the {M/adipate} system. Compound 2 possesses one-dimensional sine- or cosine-type chains, which are alternately connected together by the oxalate group to form a three-dimensional framework. The structural determination reveals that the introduction of the oxalate ligand causes the dimensional transformation of the compounds. Compounds 1 and 2 show strong fluorescent properties at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Click Chemistry Approach to Rhodamine B-Capped Polyrotaxanes and their Unique Fluorescence PropertiesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 20 2009Jiayan Wu Abstract A fluorescent polyrotaxane (PR) made from the diazido-poly(ethylene glycol) (N3 -PEG-N3) axis, , -cyclodextrins, and alkyne-functionalized rhodamine B (RhB-alk) stoppers via Cu(I)-catalyzed azide,alkyne click chemistry is reported. A nanowire-like morphology of the prepared fluorescent PRs was visualized by atomic force microscopy. The fluorescence emission intensities of RhB-capped PEG (RhB-PEG-RhB) and the PR were much higher than that of neat RhB or RhB-alk with the same concentration of RhB fluorophore in both dimethylsulfoxide and alkaline aqueous solutions. Fluorescence lifetimes were detected as 3.59, 3.31, 2.99, and 2.99,ns for neat RhB, RhB-alk, RhB-PEG-RhB, and the PR, respectively. The PRs with unique fluorescence properties might have further applications in the fields of biomedicine and bionanotechnology. [source] Chlorin,Bacteriochlorin Energy-transfer Dyads as Prototypes for Near-infrared Molecular Imaging Probes: Controlling Charge-transfer and Fluorescence Properties in Polar MediaPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Hooi Ling Kee The photophysical properties of two energy-transfer dyads that are potential candidates for near-infrared (NIR) imaging probes are investigated as a function of solvent polarity. The dyads (FbC-FbB and ZnC-FbB) contain either a free base (Fb) or zinc (Zn) chlorin (C) as the energy donor and a free base bacteriochlorin (B) as the energy acceptor. The dyads were studied in toluene, chlorobenzene, 1,2-dichlorobenzene, acetone, acetonitrile and dimethylsulfoxide (DMSO). In both dyads, energy transfer from the chlorin to bacteriochlorin occurs with a rate constant of ,(5,10 ps),1 and a yield of >99% in nonpolar and polar media. In toluene, the fluorescence yields (,f = 0.19) and singlet excited-state lifetimes (,,5.5 ns) are comparable to those of the benchmark bacteriochlorin. The fluorescence yield and excited-state lifetime decrease as the solvent polarity increases, with quenching by intramolecular electron (or hole) transfer being greater for FbC-FbB than for ZnC-FbB in a given solvent. For example, the ,f and , values for FbC-FbB in acetone are 0.055 and 1.5 ns and in DMSO are 0.019 and 0.28 ns, whereas those for ZnC-FbB in acetone are 0.12 and 4.5 ns and in DMSO are 0.072 and 2.4 ns. The difference in fluorescence properties of the two dyads in a given polar solvent is due to the relative energies of the lowest energy charge-transfer states, as assessed by ground-state redox potentials and supported by molecular-orbital energies derived from density functional theory calculations. Controlling the extent of excited-state quenching in polar media will allow the favorable photophysical properties of the chlorin,bacteriochlorin dyads to be exploited in vivo. These properties include very large Stokes shifts (85 nm for FbC-FbB, 110 nm for ZnC-FbB) between the red-region absorption of the chlorin and the NIR fluorescence of the bacteriochlorin (,f = 760 nm), long bacteriochlorin excited-state lifetime (,5.5 ns), and narrow (,20 nm) absorption and fluorescence bands. The latter will facilitate selective excitation/detection and multiprobe applications using both intensity- and lifetime-imaging techniques. [source] ChemInform Abstract: Efficient Synthesis and Fluorescence Properties of Highly Functionalized 2-Aryl-quinazolin-4(3H)-ones.CHEMINFORM, Issue 38 2009Michael Waibel Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Dramatic Effects of the Substituents on the Solid-State Fluorescence Properties of Structural Isomers of Novel Benzofuro[2,3-c]oxazolocarbazole-Type Fluorophores.CHEMINFORM, Issue 2 2007Yousuke Ooyama Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] 3-Alkyl- and 3-Aryl-7H-furo[3,2-g]-1-benzopyran-7-ones: Synthesis, Photoreactivity, and Fluorescence Properties.CHEMINFORM, Issue 44 2002Paul Koerner Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: New Approach to Synthesis of N-Substituted 9-Amino/Iminoacridines with Important Fluorescence Properties.CHEMINFORM, Issue 24 2001Pavol Kristian Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Systematic Investigation of Molecular Arrangements and Solid-State Fluorescence Properties on Salts of Anthracene-2,6-disulfonic Acid with Aliphatic Primary AminesCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2009Yuji Mizobe Dr. Abstract Organic salts of anthracene-2,6-disulfonic acid (ADS) with a wide variety of primary amines have been fabricated, and their arrangements of anthracene molecules and solid-state fluorescence properties investigated. Single-crystal X-ray studies reveal that the salts show seven types of crystal forms and corresponding molecular arrangements of anthracene moieties depending on the amine, while anthracene shows only one form and arrangement in the solid state. Depending on the molecular arrangements, the ADS salts exhibit various solid-state fluorescence properties: spectral shift (30,nm) and suppression and enhancement of the fluorescence intensity. Especially the ADS salt with n -heptylamine (nHepA), which shows discrete anthracene moieties in the crystal, exhibits the highest quantum yield (,F=46.1±0.2,%) in the series of ADS salts, which exceeds that of anthracene crystal (,F=42.9±0.2,%). From these systematic investigations on the arrangements and the solid-state properties, the following factors are essential for high fluorescence quantum yield in the solid state: prevention of contact between , planes of anthracene moieties and immobilization of anthracene rings. In addition, such organic salts have potential as a system for modulating the molecular arrangements of fluorophores and the concomitant solid-state properties. Thus, systematic investigation of this system constructs a library of arrangements and properties, and the library leads to remarkable strategies for the development of organic solid materials. [source] 2-Phenanthrenyl,DNA: Synthesis, Pairing, and Fluorescence PropertiesCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2009Nikolay Abstract Three 2,-phenanthrenyl- C -deoxyribonucleosides with donor (phenNH2), acceptor (phenNO2), or no (phenH) substitution on the phenanthrenyl core were synthesized and incorporated into oligodeoxyribonucleotides. Duplexes containing either one or three consecutive phenR residues, which were located opposite each other, were formed. Within these residues, the phenR residues are expected to recognize each other through interstrand stacking interactions, in much the same way as described previously for biphenyl DNA. The thermal, thermodynamic, and fluorescence properties of such duplexes were determined by UV melting analysis and fluorescence spectroscopy. Depending on the nature of the substituent, the thermal stability of single-modified duplexes can vary between ,2.7 to +11.3,°C in Tm and that of triple-modified duplexes from +7.8 to +11.1,°C. Van,t Hoff analysis suggested that the observed higher thermodynamic stability in phenH- and phenNO2 -containing duplexes is of enthalpic origin. A single phenH or phenNO2 residue in a bulge position also stabilizes a corresponding duplex. If a phenNO2 residue is placed in a bulge position next to a base mismatch this can lead, in a sequence-dependent manner, to duplex destabilization. The phenNO2 residue was found to be a highly efficient (10,100-fold) quencher of phenH and phenNH2 fluorescence if placed in the opposite position to the fluorophores. When phenH and phenNH2 residues were placed opposite each other, efficient quenching of phenH and enhancement of phenNH2 fluorescence was found, which is an indicator for electron- or energy-transfer processes between the aromatic units. [source] Novel copper(II) heterochelate: synthesis, structural features and fluorescence studiesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 7 2010G. J. Kharadi Abstract Fluorescence properties of four based derivatives [An] (where n = 1,4) and their Cu(II) heterochelates of the type [Cu(An)(CQ)(OH)],xH2O {where A1 = 3-(2-oxo-2H-chromen-3-yl)-4H-furo[3,2-c]chromen-4-one, A2 = 8-methyl-3-(2-oxo-2H-chromen-3-yl)-4H-furo[3,2-c]chromen-4-one, A3 = 6-methyl-3-(2-oxo-2H-chromen-3-yl)-4H-furo[3,2-c]chromen-4-one, A4 = 8-chloro-3-(2-oxo-2H-chromen-3-yl)-4H-furo[3,2-c]chromen-4-one and x = 3, 2, 4, 1} were studied at room temperature. The fluorescence spectra of heterochelates show red shift, which may be due to the chelation by the ligands to the metal ion. It enhances ligand ability to accept electrons and decreases the electron transition energy. The kinetic parameters such as order of reaction (n), energy of activation (Ea), entropy (,S#), pre-exponential factor (A), enthalpy (,H#) and Gibbs free energy (,G#) have been reported. The antimicrobial activity of Clioquinol and Cu(II) heterochelates have been determined and described. All the heterochelates showed a more effective antimicrobial activity than the free ligand. Copyright © 2010 John Wiley & Sons, Ltd. [source] Harmonization of light scatter and fluorescence flow cytometry profiles obtained after staining peripheral blood leucocytes for cell surface-only versus intracellular antigens with the Fix & PermÔ reagent,,§CYTOMETRY, Issue 1 2010Elaine Sobral da Costa Abstract Staining for intracellular markers with the Fix & PermÔ reagent is associated with variations in the scatter properties of leucocytes, limiting automated analysis of flow cytometry (FCM) data. Here, we investigated those variables significantly contributing to changes in the light scatter, autofluorescence, and bcl2 staining characteristics of peripheral blood (PB) leucocytes, after fixation with Fix & PermTM. Our major aim was to evaluate a new mathematical approach for automated harmonization of FCM data from datafiles corresponding to aliquots of a sample treated with cell-surface-only versus Fix & Perm intracellular staining techniques. Overall, neither the anticoagulant used nor sample storage for <24 h showed significant impact on the light scatter and fluorescence properties of PB leucocytes; similarly, the duration of the fixation period (once >15 min were used) had a minimum impact on the FCM properties of PB leucocytes. Conversely, changes in cell/protein concentrations and the fixative/sample (vol/vol) ratio had a clear impact on the light scatter features of some populations of leucocytes. Accordingly, lower cell/protein concentrations were associated with lower scatter values, particularly for the neutrophils. Such changes could be partially corrected through the use of higher fixative to sample volume ratios. Despite the variable changes detected between aliquots of the same sample treated with cell surface-only versus intracellular staining procedures, the new mathematical approach here proposed and evaluated for automated harmonization of common parameters in both datafiles, could correct the FCM profiles of leucocytes derived from cells undergoing conventional fixation/permeabilization procedures, and made them indistinguishable from those corresponding to aliquots of the same sample treated with cell-surface-only staining techniques. © 2009 Clinical Cytometry Society [source] DIAGNOSIS OF COLONIC ADENOMAS BY NEW AUTOFLUORESCENCE IMAGING SYSTEM: A PILOT STUDYDIGESTIVE ENDOSCOPY, Issue 2007Noriya Uedo Detection and removal of adenoma by colonoscopy is an important means of preventing cancer. Autofluorescence endoscopy can visualize flat or isochromatic tumor that was not detectable by white light endoscopy by the difference in tissue fluorescence properties. Recently, a new autofluorescence imaging system (AFI, Olympus Medical Systems) using a combination of autofluorescence and reflection imaging has been developed. The purpose of the present paper was to investigate its feasibility in detection of colonic adenoma in a clinical setting. A total of 64 patients were randomly assigned to AFI or white light groups, and the distal sigmoid colon and the rectum was observed under autofluorescence or white light followed by the other mode of observation by a different endoscopist. The diagnostic ability of each method for detection of neoplasms was compared in relation to the histology as a reference standard. Sensitivity and specificity of AFI for detection of neoplastic polyps was 84% and 60%, respectively, and were similar to those of white light colonoscopy: 90% and 64%. Conventional colonoscopy overlooked more flat lesions including one adenocarcinoma. AFI has the potential to detect more flat lesions but efficacy was unable to be demonstrated in the restricted population. Further investigations are needed to determine optimum usage. [source] Conformational and functional analysis of the lipid binding protein Ag-NPA-1 from the parasitic nematode Ascaridia galliFEBS JOURNAL, Issue 1 2005Rositsa Jordanova Ag-NPA-1 (AgFABP), a 15 kDa lipid binding protein (LBP) from Ascaridia galli, is a member of the nematode polyprotein allergen/antigen (NPA) family. Spectroscopic analysis shows that Ag-NPA-1 is a highly ordered, ,-helical protein and that ligand binding slightly increases the ordered secondary structure content. The conserved, single Trp residue (Trp17) and three Tyr residues determine the fluorescence properties of Ag-NPA-1. Analysis of the efficiency of the energy transfer between these chromophores shows a high degree of Tyr-Trp dipole-dipole coupling. Binding of fatty acids and retinol was accompanied by enhancement of the Trp emission, which allowed calculation of the affinity constants of the binary complexes. The distance between the single Trp of Ag-NPA-1 and the fluorescent fatty acid analogue 11-[(5-dimethylaminonaphthalene-1- sulfonyl)amino]undecanoic acid (DAUDA) from the protein binding site is 1.41 nm as estimated by fluorescence resonance energy transfer. A chemical modification of the Cys residues of Ag-NPA-1 (Cys66 and Cys122) with the thiol reactive probes 5-({[(2-iodoacetyl)amino]ethyl}amino) naphthalene-1-sulfonic acid (IAEDANS) and N,N,-dimethyl- N -(iodoacetyl)- N,-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)ethylenediamine (IANBD), followed by MALDI-TOF analysis showed that only Cys66 was labeled. The observed similar affinities for fatty acids of the modified and native Ag-NPA-1 suggest that Cys66 is not a part of the protein binding pocket but is located close to it. Ag-NPA-1 is one of the most abundant proteins in A. galli and it is distributed extracellularly mainly as shown by immunohistology and immunogold electron microscopy. This suggests that Ag-NPA-1 plays an important role in the transport of fatty acids and retinoids. [source] Vision enhancement system for detection of oral cavity neoplasia based on autofluorescenceHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 3 2004Ekaterina Svistun MS Abstract Background. Early detection of squamous cell carcinoma (SCC) in the oral cavity can improve survival. It is often difficult to distinguish neoplastic and benign lesions with standard white light illumination. We evaluated whether a technique that capitalizes on an alternative source of contrast, tissue autofluorescence, improves visual examination. Methods. Autofluorescence of freshly resected oral tissue was observed visually and photographed at specific excitation/emission wavelength combinations optimized for response of the human visual system and tissue fluorescence properties. Perceived tumor margins were indicated for each wavelength combination. Punch biopsies were obtained from several sites from each specimen. Sensitivity and specificity were evaluated by correlating histopathologic diagnosis with visual impression. Results. Best results were achieved with illumination at 400 nm and observation at 530 nm. Here, sensitivity and specificity were 91% and 86% in discrimination of normal tissue from neoplasia. This compares favorably with white light examination, in which sensitivity and specificity were 75% and 43%. Conclusions. Oral cavity autofluorescence can be easily viewed by the human eye in real time. Visual examination of autofluorescence enhances perceived contrast between normal and neoplastic oral mucosa in fresh tissue resections. © 2004 Wiley Periodicals, Inc. Head Neck26: 205,215, 2004 [source] Replacement of Canonical DNA Nucleobases by Benzotriazole and 1,2,3-Triazolo[4,5- d]pyrimidine: Synthesis, Fluorescence, and Ambiguous Base PairingHELVETICA CHIMICA ACTA, Issue 4 2005Frank Seela The syntheses and the fluorescence properties of 7H -3,6-dihydro-1,2,3-triazolo[4,5- d]pyrimidin-7-one 2,-deoxy- , - D -ribonucleosides (=2,-deoxy-8-azainosine) 3 (N3), 15 (N2), and 16 (N1) as well as of 1,2,3-benzotriazole 2,- O -methyl- , - or - , - D -ribofuranosides 6 (N1) and 24 (N1) are described. Also the fluorescence properties of 1,2,3-benzotriazole 2,-deoxy- , - D -ribofuranosides 4 (N1) and 5 (N2) are evaluated. From the nucleosides 3,6, the phosphoramidites 19, 26a, 26b, and 28 are prepared and employed in solid-phase oligonucleotide synthesis. In 12-mer DNA duplexes, compound 3 shows similar ambiguous base-pairing properties as 2,-deoxyinosine (1), while the nucleosides 4,6 show strong pairing with each other and discriminate very little the four canonical DNA constituents. [source] Preparation and fluorescence properties of poly(o -methyl-acrylamideyl-benzoic acid)-ZnS compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2010Qing-Feng Xu Abstract Poly(o -methyl-acrylamideyl-benzoic acid)-ZnS (P(o -MAABA)-ZnS) nanocomposites have been prepared and characterized. The resultant P(o -MAABA)-ZnS nanocomposites in solution show two emissions in the purple-light area (370 nm) and in the blue-light area (425 nm), which are assigned to the polymer and ZnS nanoparticles, respectively. The coordination between the polymer and Zn2+ and the surface chemical composition has been studied by Infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The particle size of ZnS nanoparticles was homogeneous and the average size was 3.8 nm, which were characterized by UV absorption spectrum and X-ray Diffraction. The P(o -MAABA)-ZnS composites displays good film formability and the films also show two emissions in 370 and 425 nm. After doped with Tb3+, there was effective energy transfer from ZnS nanoparticles to Tb3+. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Study on macromolecular lanthanide complexes (V): Synthesis, characterization, and fluorescence properties of lanthanide complexes with the copolymers of styrene and acrylic acidJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2009Xing Liang Abstract In this study, the luminescent macromolecular lanthanide complexes Ln-PSt/AA (Ln = Eu and Tb; St = styrene; AA = acrylic acid) have been synthesized, and an extensive characterization has been carried out by means of elemental analysis, FTIR, thermal analysis, and fluorescence determination. The results showed that the carboxylic groups on the chain of the polymers acted as bidentate ligands coordinated to lanthanide ions; and the coordination degree of COO,/Ln3+ in the macromolecular complexes was closely dependent on both the pH value of the solution and the molar ratio of St to AA in the polymeric ligands. Thermal analysis manifested that these Ln-PSt/AA (Ln = Eu and Tb) complexes had high thermal stability and solvent resistance, and these macromolecular complexes were highly crosslinked. The fluorescence determination indicated that Ln-PSt/AA complexes could emit characteristic fluorescence with comparatively high brightness and good monochromaticity, and the fluorescence intensity changed with increasing lanthanide ions content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] The pH-dependent surface properties of gelatin-alkenylsuccinic acid anhydride derived surfactantsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Li-Huei Lin Abstract The pH-dependent surface properties of a gelatin,alkenylsuccinic acid anhydride derived surfactants, containing an oligopeptide residue and alkenyl groups, were studied. The surface properties examined included surface tension, contact angle, emulsifying power, and fluorescence properties. The results showed that the surface activities of gelatin derivatives and their detergent properties for T/W fabrics are improved at low pH. These improved features make gelatin-derived surfactants suitable for use as cleaning agents for lime-degradable substrates such as hair and wool. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] A novel synthesis of benzo[h]quinolines and study of their fluorescence propertiesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2007Madhukar N. Jachak An elegant synthesis of highly fluorescent benzo[h]quinolines have been accomplished from readily available and highly economical 6-methoxy-1-tetralone in high purity and excellent yield. [source] Absorption and fluorescence properties of acridinones, thioacridinones, aminoacridines and related crown ethersJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2001Anne-Marie Patellis We report a study on the absorptive and emissive properties of 9-acridinones, 9-thioacridinones and 9-aminoacridines including six crown ether derivatives. The effect of solvents and of the addition of cations (Na+, K+, Ca2+ and Mg2+) on these properties has been studied. The absorption of the crown ether derivative of 9-thioacridinone is sensitive to solvents while the fluorescence of crown ethers derived from 9-aminoacridines shows some specificity towards cations. Empirical modeling was used to discuss the emission characteristics of these compounds. [source] Synthesis of high fluorescent silica hybrid materials by immobilization of orange peel extract in silica-silsesquioxane matrixJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 11 2009I. Lacatusu Abstract Sol,gel chemistry can be easily modified to the changing needs of society to produce fine-tuned sol,gel nanostructured materials for relevant applications. In this context, there is an increasing need for natural and versatile raw materials as well as biocompatible compounds that could be extensively used as biomarkers for bioimaging in diagnosis or therapy. Silica-based materials are widely used in the field of biomedicine due to their chemical inertness and biocompatibility. In the present paper, orange peel extract was immobilized inside inorganic silica and hybrid silica-silsesquioxane polymeric networks. Silica and organo-modified silica matrices were synthesized through a templated sol,gel route of TEOS and an organosilsesquioxane (octaisobutyltetracyclo[7.3.3.15,11] octasiloxane- endo -3,7-diol), with D -glucose as template, and for comparison a non-ionic surfactant (tetraethylene glycol mono-hexadecyl ether) was also used. The bioactive properties of the molecules from orange peel extract were preserved after immobilization in both silica and silica-silsesquioxane networks. Moreover, the fluorescence properties were amplified by 10,20 times more than the native orange peel extract. The structural properties of the final materials have been studied by FT-IR, UV,Vis-NIR, and fluorescence spectroscopy. Dynamic light scattering measurements and transmission electron microscopy were used to estimate the size and morphology of the hybrid materials with orange peel extract immobilized in silica networks. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthesis and fluorescence properties of a porphyrin,fullerene molecular wire,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 9 2004Sean A. Vail Abstract The synthesis and photophysical studies of a butadiyne-linked porphyrin,C60 dyad (ZnP,C60) 6 are described. This is the first porphyrin,[60]fullerene dyad in which the two chromophores are conjugatively linked through a ,molecular wire'. The UV,visible absorption spectrum for dyad 6 is slightly red shifted relative to the porphyrin precursor 5 whose fluorescence is all but quenched by the attached C60. Copyright © 2004 John Wiley & Sons, Ltd. [source] Synthesis and spectroscopic characterization of symmetrical isoprene,methyl methacrylate diblock copolymers bearing different anthracene derivatives at the junctionsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2003Jian Yang Abstract We describe the synthesis and characterization of 1-(1-anthryl)-1-phenylethylene (1-An-E) and 1-(2-anthryl)-1-phenylethylene (2-An-E). These species were used to end cap the living end group of polyisoprene (PI) obtained by anionic polymerization in tetrahydrofuran. The anions generated were used to initiate methyl methacrylate polymerization. In this way, we synthesized two symmetrical PI-poly(methyl methacrylate) (PMMA) block copolymers each with a single dye at the junction. PI-An1-PMMA has an anthracene linked via its 1-position. PI-An2-PMMA has the anthracene linked via its 2-position. We compare the UV and fluorescence properties of the polymers to model compounds with similar chromophores. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1225,1236, 2003 [source] Optimal methods for fluorescence and diffuse reflectance measurements of tissue biopsy samplesLASERS IN SURGERY AND MEDICINE, Issue 3 2002Gregory M. Palmer BS Abstract Background and Objective In developing fluorescence spectroscopy systems for the in vivo detection of pre-cancer and cancer, it is often necessary to perform preliminary testing on tissue biopsies. Current standard protocols call for the tissue to be immediately frozen after biopsy and later thawed for spectroscopic analysis, but this process can have profound effects on the spectroscopic properties of tissue. This study investigates the optimal tissue handling methods for in vitro fluorescence spectroscopy studies. Study Design/Materials and Methods The epithelial tissue of the Golden Syrian hamster cheek pouch was used in this study. Three specific experiments were carried out. First, the fluorescence properties of tissues in vivo and of frozen and thawed tissue biopsies were characterized at multiple excitation wavelengths spanning the ultraviolet-visible (UV-VIS) spectrum. Next, comparison of tissue fluorescence emission spectra in vivo, ex vivo (immediately after biopsy), and after the freeze and thaw process were systematically carried out at the excitation wavelengths corresponding to the previously identified fluorescence peaks. Lastly, intensities at the excitation and emission wavelength pairs corresponding to the fluorescence peaks were measured as a function of time after biopsy. Diffuse reflectance measurements over the UV-VIS spectrum were also made to evaluate the effects of oxygenation, blood volume, and scattering on the tissue fluorescence at these different excitation,emission wavelengths. Results This study indicates that the freezing and thawing process produces a significant deviation in intensity and lineshape relative to the in vivo fluorescence emission spectral data over the entire UV-VIS range between 300 and 700 nm. By contrast, examination of ex vivo emission spectra reveals that it closely preserves both the intensity and lineshape of the in vivo emission spectra except between 500 and 700 nm. The observed deviations can be explained by the diffuse reflectance measurements, which suggest increased hemoglobin deoxygenation and wavelength dependent changes in scattering in ex vivo tissues, and increased total hemoglobin absorption in the frozen and thawed samples. Furthermore, it was found that over a time window of 1.5 hours, spectroscopic changes brought about by degradation of the tissue due to biopsy or other factors are significantly smaller (10,30% variations in intensity) than those associated with the freezing and thawing process (50,70% decrease in intensity). Conclusions It was found that the effects of freezing and thawing on the fluorescence properties of tissue are greater than any changes brought about by degradation of tissue over a time frame of 90 minutes after biopsy. Performing ex vivo fluorescence measurements within a reasonable time window has the advantage of more accurately reproducing the clinically relevant in vivo conditions in the case of the hamster cheek pouch tissue. Therefore, in tissue biopsy studies, the tissue sample should ideally be maintained in an unfrozen state prior to measurement. Lasers Surg. Med. 30:191-200, 2002. © 2002 Wiley-Liss, Inc. [source] Effects of the grafting on the fluorescence properties of CdTe nanocrystalsLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2009Fang Mei Abstract In this paper, we systematically investigated the influence of graft reagents having an amino or a carboxyl terminus with different chain lengths on the fluorescence properties of water-soluble thioglycolic acid-stabilized CdTe nanocrystals (TGA,CdTe). Strong enhancement effects of the grafting on the fluorescence intensity of TGA,CdTe were observed. The experiment results demonstrated that short-chain-length grafting can increase the fluorescence intensity of CdTe nanocrystals (NCs) better than long-chain-length grafting, and the grafting did not influence the emission wavelength of the CdTe NCs. The fluorescence intensity of the carboxyl-grafted TGA,CdTe was more stable than that of the amino-grafted TGA,CdTe at wide pH ranges (pH 5.1,10.0). Copyright © 2009 John Wiley & Sons, Ltd. [source] Iron-Containing Poly(propylene imine) Dendromesogens with Photoactive PropertiesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 7 2010Natalia E. Domracheva Abstract Here, we report the first results of investigation the local structure and photoactive properties of iron-containing dendromesogens based on decyloxybenzoate substituted poly(propylene imine) dendrimers of the first to fifth generations. Iron ions existing in a high-spin state are coordinated in dendrimer ligands by two kinds of iron-complexing sites with an octahedral and a tetrahedral symmetry. Octahedral (high-symmetry) centers are located at the border of the dendrimeric core, while the tetrahedral centers with strong rhombic distortion of iron environment are distributed throughout all branching of the dendrimeric core. It has been found that all iron-containing dendromesogens exhibit light-harvesting and fluorescence properties. [source] Click Chemistry Approach to Rhodamine B-Capped Polyrotaxanes and their Unique Fluorescence PropertiesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 20 2009Jiayan Wu Abstract A fluorescent polyrotaxane (PR) made from the diazido-poly(ethylene glycol) (N3 -PEG-N3) axis, , -cyclodextrins, and alkyne-functionalized rhodamine B (RhB-alk) stoppers via Cu(I)-catalyzed azide,alkyne click chemistry is reported. A nanowire-like morphology of the prepared fluorescent PRs was visualized by atomic force microscopy. The fluorescence emission intensities of RhB-capped PEG (RhB-PEG-RhB) and the PR were much higher than that of neat RhB or RhB-alk with the same concentration of RhB fluorophore in both dimethylsulfoxide and alkaline aqueous solutions. Fluorescence lifetimes were detected as 3.59, 3.31, 2.99, and 2.99,ns for neat RhB, RhB-alk, RhB-PEG-RhB, and the PR, respectively. The PRs with unique fluorescence properties might have further applications in the fields of biomedicine and bionanotechnology. [source] Imaging FRET standards by steady-state fluorescence and lifetime methodsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 12 2007Beatriz Domingo Abstract Imaging fluorescence resonance energy transfer (FRET) between molecules labeled with fluorescent proteins is emerging as a powerful tool to study changes in ions, ligands, and molecular interactions in their physiological cellular environment. Different methods use either steady-state fluorescence properties or lifetime to quantify the FRET rate. In addition, some provide the absolute FRET efficiency whereas others are simply a relative index very much influenced by the actual settings and instrumentation used, which makes the interpretation of a given FRET rate very difficult. The use and exchange of FRET standards in laboratories using these techniques would help to overcome this drawback. We report here the construction and systematic evaluation of FRET standard probes of varying FRET efficiencies. The standards for intramolecular FRET were protein fusions of the cyan and yellow variants of A. victoria green fluorescent protein (ECFP and citrine) joined by short linkers or larger protein spacers, or ECFP tagged with a tetracysteine motif and labeled with the biarsenical fluorochrome, FlAsH. Negative and positive controls of intermolecular FRET were also used. We compared these FRET standards with up to four FRET quantification methods: ratioing of acceptor to donor emission, donor intensity recovery upon acceptor photobleach, sensitized emission after spectral unmixing of raw images, and fluorescence lifetime imaging (FLIM). The latter was obtained with a frequency-domain setup able to provide high quality lifetime images in less than a second, and is thus very well suited for live cell studies. The FRET rates or indexes of the standards were in good agreement regardless of the method used. For the CFP-tetraCys/FlAsH pair, the rate calculated from CFP quenching was faster than that obtained by FLIM. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source] Chlorin,Bacteriochlorin Energy-transfer Dyads as Prototypes for Near-infrared Molecular Imaging Probes: Controlling Charge-transfer and Fluorescence Properties in Polar MediaPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Hooi Ling Kee The photophysical properties of two energy-transfer dyads that are potential candidates for near-infrared (NIR) imaging probes are investigated as a function of solvent polarity. The dyads (FbC-FbB and ZnC-FbB) contain either a free base (Fb) or zinc (Zn) chlorin (C) as the energy donor and a free base bacteriochlorin (B) as the energy acceptor. The dyads were studied in toluene, chlorobenzene, 1,2-dichlorobenzene, acetone, acetonitrile and dimethylsulfoxide (DMSO). In both dyads, energy transfer from the chlorin to bacteriochlorin occurs with a rate constant of ,(5,10 ps),1 and a yield of >99% in nonpolar and polar media. In toluene, the fluorescence yields (,f = 0.19) and singlet excited-state lifetimes (,,5.5 ns) are comparable to those of the benchmark bacteriochlorin. The fluorescence yield and excited-state lifetime decrease as the solvent polarity increases, with quenching by intramolecular electron (or hole) transfer being greater for FbC-FbB than for ZnC-FbB in a given solvent. For example, the ,f and , values for FbC-FbB in acetone are 0.055 and 1.5 ns and in DMSO are 0.019 and 0.28 ns, whereas those for ZnC-FbB in acetone are 0.12 and 4.5 ns and in DMSO are 0.072 and 2.4 ns. The difference in fluorescence properties of the two dyads in a given polar solvent is due to the relative energies of the lowest energy charge-transfer states, as assessed by ground-state redox potentials and supported by molecular-orbital energies derived from density functional theory calculations. Controlling the extent of excited-state quenching in polar media will allow the favorable photophysical properties of the chlorin,bacteriochlorin dyads to be exploited in vivo. These properties include very large Stokes shifts (85 nm for FbC-FbB, 110 nm for ZnC-FbB) between the red-region absorption of the chlorin and the NIR fluorescence of the bacteriochlorin (,f = 760 nm), long bacteriochlorin excited-state lifetime (,5.5 ns), and narrow (,20 nm) absorption and fluorescence bands. The latter will facilitate selective excitation/detection and multiprobe applications using both intensity- and lifetime-imaging techniques. [source] | ||||||||||||||||||||||||||||||||||