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961.
A series of three inter-related synthetic routes to a water soluble alkyne substituted BF2-azadipyrromethene fluorochrome is described. Each route allows for the introduction of the required reactive alkynyl group and water solubilizing propane-sulfonic acid through either more advanced pyrrole intermediates or through their earlier synthetic precursors. The advantages and disadvantages of each route lie in the number of synthetic steps required versus the formation of undesired azadipyrromethene by-products. Upon its synthesis, the alkyne-bearing fluorochrome was shown to efficiently participate in CuACC reactions with a series of azido substrates in water at room temperature and 37?°C. NIR-photophysical properties of the fluorochrome and its conjugates were similar, showing strong potential for in vitro and in vivo imaging applications. 相似文献
962.
Dr. Emmanouil Zacharioudakis Poonam Agarwal Dr. Alexandra Bartoli Nathan Abell Lavaniya Kunalingam Dr. Valérie Bergoglio Dr. Blerta Xhemalce Dr. Kyle M. Miller Dr. Raphaël Rodriguez 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(23):6583-6587
Cisplatin derivatives can form various types of DNA lesions (DNA-Pt) and trigger pleiotropic DNA damage responses. Here, we report a strategy to visualize DNA-Pt with high resolution, taking advantage of a novel azide-containing derivative of cisplatin we named APPA, a cellular pre-extraction protocol and the labeling of DNA-Pt by means of click chemistry in cells. Our investigation revealed that pretreating cells with the histone deacetylase (HDAC) inhibitor SAHA led to detectable clusters of DNA-Pt that colocalized with the ubiquitin ligase RAD18 and the replication protein PCNA. Consistent with activation of translesion synthesis (TLS) under these conditions, SAHA and cisplatin cotreatment promoted focal accumulation of the low-fidelity polymerase Polη that also colocalized with PCNA. Remarkably, these cotreatments synergistically triggered mono-ubiquitination of PCNA and apoptosis in a RAD18-dependent manner. Our data provide evidence for a role of chromatin in regulating genome targeting with cisplatin derivatives and associated cellular responses. 相似文献
963.
Interplay between solid state microstructure and photophysics for poly(9,9‐dioctylfluorene) within oriented polyethylene hosts
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Aleksandr Perevedentsev Seda Aksel Kirill Feldman Paul Smith Paul N. Stavrinou Donal D. C. Bradley 《Journal of Polymer Science.Polymer Physics》2015,53(1):22-38
We present a study of isotropic and uniaxially oriented binary blend films comprising ≤1 wt % of the conjugated polymer poly(9,9‐dioctylfluorene) (PFO) dispersed in both ultra‐high molecular weight (UHMW) and linear‐low‐density (LLD) polyethylene (PE). Polarized absorption, fluorescence and Raman spectroscopy, scanning electron microscopy, and X‐ray diffraction are used to characterize the samples before and after tensile deformation. Results show that blend films can be prepared with PFO chains adopting a combination of several distinct molecular conformations, namely glassy, crystalline, and the so‐called β‐phase, which directly influences the resulting optical properties. Both PFO concentration and drawing temperature strongly affect the alignment of PFO chains during the tensile drawing of the blend films. In both PE hosts, crystallization of PFO takes place during drawing; the resulting ordered chains show optimal optical anisotropy. Our results clarify the PFO microstructure in oriented blends with PE and the processing conditions required for achieving the maximal optical anisotropy. © 2014 The Authors. Journal of Polymer Science Part B: Polymer Physics Published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 22–38 相似文献
964.
The synthesis of well-aggregated carbon nanotubes in the form of bundles was achieved by the catalytic reduction of 1,2-dichlorobenzene by a solvothermal approach. The use of 1,2-dichlorobenzene as a carbon source yielded a comparably good percentage of carbon nanotubes in the range of 60–70 %, at a low reaction temperature of 200°C. The products obtained were analysed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. The X-ray diffraction studies implied the presence of pure, crystalline, and well-ordered carbon nanotubes. The scanning electron and transmission electron microscopic images revealed the surface morphology, dimensions and the bundled form of the tubes. These micrographs showed the presence of multi-walled carbon nanotubes with an outer diameter of 30–55 nm, inner diameter of 15–30 nm, and lengths of several hundreds of nanometers. Brunauer-Emmett-Teller-based N2 gas adsorption studies were performed to determine the surface area and pore volume of the carbon nanotubes. These carbon nanotubes exhibit a better surface area of 385.30 m2 g?1. In addition, the effects of heating temperature, heating time, amount of catalyst and amount of carbon source on the product yield were investigated. 相似文献
965.
966.
Sahaj GuptaPiyush K. Agarwal Mohammad SaifuddinBijoy Kundu 《Tetrahedron letters》2011,52(44):5752-5757
An efficient strategy for the stereo- and regio-selective synthesis of N-alkenynes has been described. The salient feature of the reaction involves hydro-amination/amidation of 1,3-diynes with indoles/azoles/amides via transition-metal catalyzed activation of N-H bond. The resulting N-alkenynes derived from N-heterocycles and cyclic amides were obtained as a mixture of Z/E isomers with Z-stereoselectivity ranging from 60% to 95%. In contrast, acyclic amides afforded N-alkenynes with exclusive E-stereoselectivity, albeit in reduced yield ranging from ∼10% to 41%. 相似文献
967.
Bartlett AP Agarwal AK Yethiraj A 《Langmuir : the ACS journal of surfaces and colloids》2011,27(8):4313-4318
Order-disorder transitions in colloidal systems are an attractive option for making switchable materials. Electric-field-driven order-disorder transitions are especially attractive for this purpose because the tuning parameter is easily and externally controllable. However, precise positional control of 3D structure is immensely challenging. Using patterned electrodes, we demonstrate that ac electric fields-dominantly dielectrophoresis (DEP) coupled with an electrohydrodynamic mechanism consisting of induced-charge electro-osmosis (ICEO)-can be used to template colloidal order dynamically in three dimensions. We find that the electric field geometry dictates the location, size, and shape of colloidal patterns and can produce patterns with surprising complexity. 相似文献
968.
Sinkel C Schwarzer MC Frenking G Greiner A Agarwal S 《Magnetic resonance in chemistry : MRC》2011,49(2):70-75
Heterodimers based on the polymer-bound chromophore 4-methylcoumarin and the prodrug 1-heptanoyl-5-fluorouracil, synthesized by photochemical [2 + 2]-cycloaddition are promising photoresponsive drug depots. Drug release experiments are one possibility to deliver proof of a successful reversible drug immobilization, whereas NMR spectroscopy is a potent tool for further structural characterization of these polymer-bound heterodimers. In case of the random copolymer poly(methyl methacrylate-co-7-(2'-methacryloyloxyethoxy)-4-methylcoumarin) three dimers have been identified of which the syn head-to-tail was the predominant one. In contrast, only the syn head-to-head dimer was formed in reasonable yield when the 4-methylcoumarin monofunctionalized pMMA was used as the base polymer. 1D and 2D NMR spectroscopic techniques combined with some theoretical calculations helped in successfully closing one major gap concerning polymer bound 4-methylcoumarin/1-heptanoyl-5-fluorouracil heterodimers that are of potential use in photoresponsive drug delivery devices. 相似文献
969.
Gensheimer M Brandis-Heep A Agarwal S Thauer RK Greiner A 《Macromolecular bioscience》2011,11(3):333-337
Physically crosslinked PVA-hydrogel microparticles are utilized for encapsulation of E. coli and M. luteus. The bacteria survive dry storage or treatment with bacteria-hostile organic solvents significantly better than unprotected bacteria as proven by culture-test experiments. The bacteria-protecting PVA microparticles are available for standard polymer-solution-processing techniques, as exemplarily shown by co-electrospinning of living bacteria encapsulated in dry PVA-hydrogel microparticles together with PVB-, PLLA-, and PCL-form organic solvents. 相似文献
970.
Agarwal B Petersson F Jürschik S Sulzer P Jordan A Märk TD Watts P Mayhew CA 《Analytical and bioanalytical chemistry》2011,400(8):2631-2639
The first reported use of proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) for the detection of a range
of illicit and prescribed drugs is presented here. We describe the capabilities of PTR-TOF-MS to detect the following commonly
used narcotics—ecstasy (N-methyl-3,4-methylenedioxyamphetamine), morphine, codeine, cocaine and heroin—by the direct sampling of the headspace above
small solid quantities (approximately 50 mg) of the drugs placed in glass vials at room temperature, i.e. with no heating
of the sample and no pre-concentration. We demonstrate in this paper the ability to identify the drugs, both illicit and prescribed,
using PTR-TOF-MS through the accurate m/z assignment of the protonated parent molecule to the second decimal place. We have also included in this study measurements
with an impure sample of heroin, containing typical substances found in “street” heroin, to illustrate the use of the technology
for more “real-world” samples. Therefore, in a real-world complex chemical environment, a high level of confidence can be
placed on the detection of drugs. Although the protonated parent is observed for all drugs, the reactant channel leading to
this species is not the only one observed and neither is it necessarily the most dominant. Details on the observed fragmentation
behaviour are discussed and compared to electrospray ionisation MSn studies available in the literature. 相似文献