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51.
Suman Dhami Garry Rumbles Alexander J. MacRobert David Phillips 《Photochemistry and photobiology》1997,65(1):85-90
Abstract— The photophysical properties of cis -disulfonated aluminum phthalocyanine (AlPcS2 ) in unilamellar vesicles (liposomes) of DL-a-dipalmitoyl-phosphatidylcholine have been measured. Both the fluorescence and triplet quantum yields decreased with increasing sensitizer concentration. The time-resolved fluorescence decays, analyzed by both the sum of exponentials and decay time distribution analyses, are compared with those reported for AlPcS2 in leukemic K562 cells. Information on the pho-todynamic transport and localization mechanism has been obtained by drawing correlations between the two systems, indicating active transport of the phthalocyanine into tumor cells involving lysosomal accumulation. 相似文献
52.
Microwave induced delayed phosphorescence (MIDP) measurements have been performed in the 00 bands of the phosphorescence spectrum of benzene dissolved in two phases of cyclohexane. From the relative radiative rates for decay of the three zero-field levels it is concluded that on the average the symmetry of the electronic structure is lower than D2h. In the monoclinic low temperature stable phase of cyclohexane (phase II) the structure is approximately antiquinoidal, and in the metastable phase III it is approximately quinoidal. 相似文献
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Heilemann M Tinnefeld P Sanchez Mosteiro G Garcia Parajo M Van Hulst NF Sauer M 《Journal of the American Chemical Society》2004,126(21):6514-6515
We demonstrate the synthesis and spectroscopic characterization of an unidirectional photonic wire based on four highly efficient fluorescence energy-transfer steps (FRET) between five spectrally different chromophores covalently attached to double-stranded DNA. The DNA-based modular conception enables the introduction of various chromophores at well-defined positions and arbitrary interchromophore distances. While ensemble fluorescence measurements show overall FRET efficiencies between 15 and 30%, single-molecule spectroscopy performed on four spectrally separated detectors easily uncovers subpopulations that exhibit overall FRET efficiencies of up to approximately 90% across a distance of 13.6 nm and a spectral range of approximately 200 nm. Fluorescence trajectories of individual photonic wires show five different fluorescence intensity patterns which can be ascribed to successive photobleaching events. 相似文献
57.
Amari JV Lian Z Lowden T deAlwis U Levesque P 《Journal of chromatographic science》2003,41(5):234-240
A reversed-phase high-performance liquid chromatography method using evaporative light-scattering detection is developed for the determination of residual octylglucoside (OG) levels after a detergent exchange step for in-process samples of a vaccine antigen. The reversed-phase column not only provides separation of the OG but also functions as an extraction column to remove the vaccine antigen from the sample, thereby eliminating off-line sample manipulations. In addition to column selection, the mobile phase is optimized to enhance extraction and separation. The vaccine antigen is irreversibly bound to the column, allowing nonprotein components to interact with the column for separation and elution. The assay is linear over the range of 0.00050-0.050% OG. Precision tested at 0.0010% and 0.0050% OG is 2.9% and 7.2% relative standard deviation, respectively. The limits of quantitation and detection are determined to be 0.00050 and 0.000125% OG, respectively. Accuracy is determined to be 103 and 98%, based on spike recoveries of 0.0010% and 0.0050% OG, respectively. 相似文献
58.
Kozo Arai Atsushi Matsunaga Masaru Yoneyama Shoji Takigami Yoshio Nakamura Haydn E. Edwards Glyn O. Phillips 《Journal of polymer science. Part A, Polymer chemistry》1993,31(1):249-258
The reactions of heparin with 2,4,6-trinitrobenzenesulfonic acid (TNBS) were studied spectrometrically. Seven different commercial heparins were used in this study. The amino groups react with TNBS to form equimolar amounts of trinitrophenylated (TNP) amino groups and bisulfite ions. The TNP-amino groups further react with bisulfite ions to form the monosubstituted anionic sigma complex. The absorption spectrum with two maxima at approximately 350 nm and approximately 420 nm, characteristic of either the TNP-amino groups or the complex, was analyzed for the reaction of TNBS with heparin. It was shown that the reactivities of TNBS with amino groups from α-amino acid and hexosamine residues are greatly different. By combining the results of the reaction kinetics and the reaction of heparin with Sanger's reagent, the number of the α-amino groups and the free amino groups in hexosamine residues were determined. These data have been performed with a range of heparins from different commercial sources, of different activities and physical characteristics. No correlation was found between the free amino contents of these heparins and biological potency. © 1993 John Wiley & Sons, Inc. 相似文献
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A cyclic dinucleotide with a butylene linker between the upper 2'-C position and the 3'-O-phosphate linkage was synthesised from simple nucleoside building blocks via a tandem ring-closing metathesis and hydrogenation procedure. The major of two phosphorus epimers was incorporated into an oligodeoxynucleotide, as well as into an LNA-DNA mixmer oligonucleotide. These were evaluated as parts in three different secondary structures, a duplex, a bulged duplex and a three-way junction, with both DNA and RNA complements. In the DNA:RNA hybrid molecule, the oligodeoxynucleotide containing this single 2'-C to 3'-O-phosphate butylene linkage was found to stabilise a three-way junction. 相似文献