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141.
Emilie Boulard Vivien Zibulski Luisa Oertel Dr. Philip Lienau Dr. Martina Schäfer Dr. Ursula Ganzer Dr. Ulrich Lücking 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4378-4388
A short synthetic approach with broad scope to access five- to seven-membered cyclic sulfoximines in only two to three steps from readily available thiophenols is reported. Thus, simple building blocks were converted to complex molecular structures by a sequence of S-alkylation and one-pot sulfoximine formation, followed by intramolecular cyclization. Seventeen structurally diverse cyclic sulfoximines were prepared in high overall yields. In vitro evaluation of these underrepresented, three-dimensional, cyclic sulfoximines with respect to properties relevant to medicinal chemistry did not reveal any intrinsic flaw for application in drug discovery. 相似文献
142.
ChemMatrix, a poly(ethylene glycol)-based support for the solid-phase synthesis of complex peptides 总被引:5,自引:0,他引:5
García-Martín F Quintanar-Audelo M García-Ramos Y Cruz LJ Gravel C Furic R Côté S Tulla-Puche J Albericio F 《Journal of combinatorial chemistry》2006,8(2):213-220
CM (ChemMatrix) resin is a new, totally poly(ethylene glycol) (PEG)-based resin, made exclusively from primary ether bonds and, therefore, highly chemically stable. It exhibits good loading and is user-friendly because of its free-flowing form upon drying. It performs excellently for the preparation of hydrophobic, highly structured, and poly-Arg peptides, as compared to polystyrene (PS) resins. In the most striking example, stepwise solid-phase assembly of the highly complex beta-amyloid (1-42) peptide resulted in a crude material of 91% purity. In contrast, literature procedures using PS or PEG-PS-based resins for this peptide required convergent approaches, additional time-consuming steps, or both. In addition to the difficulties of its synthesis, characterization of the beta-amyloid (1-42) peptide as a monomer is also a challenge, and methods for characterization by HPLC and MALDI-TOF have also been developed. 相似文献
143.
Jozef Rychlý Martina Hudáková Lyda Rychlá 《Journal of Thermal Analysis and Calorimetry》2014,115(1):527-535
The burning of polyethylene in the mixture with aluminium hydroxide, aluminium oxide, cellulose and Irganox 1010 has been examined by cone calorimeter under non-standard sizes of the sample. The time to ignition of pure polyethylene decreases with decreasing initial amount of polyethylene powder. The subtraction of the mass of water released from the total mass lost for polyethylene with aluminium hydroxide give the same values of effective heats of combustion as for pure polyethylene up to the load about 50 mass% of aluminium hydroxide. The mean heats of combustion determined from the cone calorimeter software are higher than those determined from the total oxygen consumed and mass lost multiplied by the factor 13.1. The additivity rule was found for effective heat of combustion and total smoke released for polyethylene with cellulose. The free radical scavenger Irganox 1010 does not show a significant effect on the flammability of polyethylene except for the increase of the total smoke released. The equation describing the heat release rate evolution in time has been proposed showing a good fit to the experimental runs. 相似文献
144.
Polymersomes Prepared from Thermoresponsive Fluorescent Protein–Polymer Bioconjugates: Capture of and Report on Drug and Protein Payloads 下载免费PDF全文
Chin Ken Wong Alistair J. Laos Dr. Alexander H. Soeriyadi Prof. Jörg Wiedenmann Prof. Paul M. G. Curmi Prof. J. Justin Gooding Dr. Christopher P. Marquis Prof. Martina H. Stenzel Assoc. Prof. Pall Thordarson 《Angewandte Chemie (International ed. in English)》2015,54(18):5317-5322
Polymersomes provide a good platform for targeted drug delivery and the creation of complex (bio)catalytically active systems for research in synthetic biology. To realize these applications requires both spatial control over the encapsulation components in these polymersomes and a means to report where the components are in the polymersomes. To address these twin challenges, we synthesized the protein–polymer bioconjugate PNIPAM‐b‐amilFP497 composed of thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) and a green‐fluorescent protein variant (amilFP497). Above 37 °C, this bioconjugate forms polymersomes that can (co‐)encapsulate the fluorescent drug doxorubicin and the fluorescent light‐harvesting protein phycoerythrin 545 (PE545). Using fluorescence lifetime imaging microscopy and Förster resonance energy transfer (FLIM‐FRET), we can distinguish the co‐encapsulated PE545 protein inside the polymersome membrane while doxorubicin is found both in the polymersome core and membrane. 相似文献
145.
Structure of Framework Aluminum Lewis Sites and Perturbed Aluminum Atoms in Zeolites as Determined by 27Al{1H} REDOR (3Q) MAS NMR Spectroscopy and DFT/Molecular Mechanics 下载免费PDF全文
Dr. Jiří Brus Libor Kobera Dr. Wolfgang Schoefberger Dr. Martina Urbanová Petr Klein Dr. Petr Sazama Dr. Edyta Tabor Dr. Stepan Sklenak Dr. Anna V. Fishchuk Dr. Jiří Dědeček 《Angewandte Chemie (International ed. in English)》2015,54(2):541-545
Zeolites are highly important heterogeneous catalysts. Besides Brønsted SiOHAl acid sites, also framework AlFR Lewis acid sites are often found in their H‐forms. The formation of AlFR Lewis sites in zeolites is a key issue regarding their selectivity in acid‐catalyzed reactions. The local structures of AlFR Lewis sites in dehydrated zeolites and their precursors—“perturbed” AlFR atoms in hydrated zeolites—were studied by high‐resolution MAS NMR and FTIR spectroscopy and DFT/MM calculations. Perturbed framework Al atoms correspond to (SiO)3AlOH groups and are characterized by a broad 27Al NMR resonance (δi=59–62 ppm, CQ=5 MHz, and η=0.3–0.4) with a shoulder at 40 ppm in the 27Al MAS NMR spectrum. Dehydroxylation of (SiO)3AlOH occurs at mild temperatures and leads to the formation of AlFR Lewis sites tricoordinated to the zeolite framework. Al atoms of these (SiO)3Al Lewis sites exhibit an extremely broad 27Al NMR resonance (δi≈67 ppm, CQ≈20 MHz, and η≈0.1). 相似文献
146.
Martina Astrová Ladislav Kurc Libor erveny 《Reaction Kinetics and Catalysis Letters》2006,89(2):311-318
Summary Condensation of ephedrine with benzaldehyde, an acid catalyzed reversible reaction, producing 3,4-dimethyl-2,5-diphenyl-1,3-oxazolidine,
was studied. If the starting reaction mixture contained acetic acid, it quantitatively reacted with ephedrine and produced
a salt functioning as an acid catalyst. On the contrary, ephedrine hydrochloride had no catalytic effect. 相似文献
147.
Portable chemiluminescence multiplex biosensor for quantitative detection of three B19 DNA genotypes
Mara Mirasoli Francesca Bonvicini Luisa Stella Dolci Martina Zangheri Giorgio Gallinella Aldo Roda 《Analytical and bioanalytical chemistry》2013,405(2-3):1139-1143
A miniaturized multiplex biosensor exploiting a microfluidic oligonucleotide array and chemiluminescence (CL) lensless imaging detection has been developed for parvovirus B19 genotyping. The portable device consists of a reaction chip, comprising a glass slide arrayed with three B19 genotype-specific probes and coupled with a polydimethylsiloxane microfluidic layer, and a charge-coupled device camera modified for lensless CL imaging. Immobilized probes were used in DNA hybridization reactions with biotin-labeled targets, and then hybrids were measured by means of an avidin-horseradish peroxidase (HRP) conjugate and CL detection. All hybridization assay procedures have been optimized to be performed at room temperature through the microfluidic elements of the reaction chip, with sample and reagents delivery via capillary force exploiting adsorbent pads to drive fluids along the microchannels. The biosensor enabled multiplex detection of all B19 genotypes, with detectability down to 80 pmol?L?1 for all B19 genotype oligonucleotides and 650 pmol?L?1 for the amplified product of B19 genotype 1, which is comparable with that obtained in traditional PCR-ELISA formats and with notably shorter assay time (30 min vs. 2 h). The specificity of the assay has been evaluated by performing DNA–DNA hybridization reactions among sequences with different degrees of homology, and no cross hybridizations among B19 genotypes have been observed. The clinical applicability has been demonstrated by assaying amplified products obtained from B19 reference serum samples, with results completely consistent with the reference PCR-ELISA method. The next crucial step will be integration in the biosensor of a miniaturized PCR system for DNA amplification and for heat treatment of amplified products. Figure
A portable multiplex biosensor was developed for detection and genotyping of parvovirus B19 DNA, exploiting lensless CL imaging. The reaction chip is composed of a polydimethylsiloxane microfluidic layer coupled with a glass slide on which oligonucleotide probes specific for three different B19 genotypes are covalently immobilized in a 3?×?3 array. The reaction chip was used in hybridization reactions with biotin-labeled targets and then hybrids were then detected by means of an avidin-HRP conjugate, upon addition of a CL substrate for HRP 相似文献
148.
The structure and the physical properties of several polyamide 66 (PA66)/polyamide 12 (PA12) blends containing different amounts of the two polymers and obtained by melt‐blending have been investigated. A low amount of organically‐modified layered silicate (OMLS, 4 wt%) has also been introduced in order to further improve the physical properties and, in particular, to evaluate its effect on the blends' structure and components' miscibility. The microstructure and morphology of all the composites were analyzed by means of X‐Ray diffraction (WAXD), transmission electron microscopy (TEM), and high resolution scanning electron microscopy (SEM), while the macroscopic scale properties (mechanical behavior and water adsorption) were assessed in order to investigate and understand the materials' structure–properties relationships. The partial miscibility of PA66 and PA12, with phase separation depending on blend composition, has been confirmed. The results also underlined the possibility to tailor the behavior of polymer blends in terms of mechanical water adsorption properties by varying the amount of PA12, added to PA66 with and without the addition of the OLMS. The effectiveness of the clay in modifying the components' miscibility as well as its tendency to segregate preferentially within separate PA66 domains have been assessed. WAXD results showed opposite effects of PA12 and clay on the crystallization behavior of PA66, an aspect that has also been deepened in another paper by the same authors discussing the results of the complete thermal characterization. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
149.
150.
Mikolasch A Wurster M Lalk M Witt S Seefeldt S Hammer E Schauer F Jülich WD Lindequist U 《Chemical & pharmaceutical bulletin》2008,56(7):902-907
Novel cephalosporins, penicillins, and carbacephems were synthesized by amination of catechols with amino-beta-lactams like cefadroxil, amoxicillin, ampicillin and the structurally related carbacephem loracarbef using laccase from Trametes sp. All isolated monoaminated products inhibited the growth of several Gram positive bacterial strains in the agar diffusion assay, among them methicillin-resistant Staphylococcus aureus strains and vancomycin-resistant Enterococci. Observed differences in the cytotoxicity and in vivo activity in a "Staphylococcus-infected, immune suppressed mouse" model are discussed. 相似文献