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311.
The solution structures formed by coil-coil copolymers arise from the selective solvation of one of the two blocks and have been well described. In most cases in such relatively simple synthetic structures there are no specific attractive forces that can aid the aggregation process. Nature, however, provides plenty of inspiring polymeric architectures that are shaped and ordered hierarchically by noncovalent forces. The high level of structural definition displayed by proteins, for example, is unmatched by synthetic polymers. An emerging area of interest in polymer science tries to combine the best of both worlds, the natural and the synthetic, by conjugating synthetic polymers and beta-sheet-forming peptides. Understanding the supramolecular organization of the block copolymers driven exclusively by the intermolecular attractive forces of the peptide sequence is of particular interest. Not only do these peptide-polymer hybrid structures present an interesting new class of materials, they can also provide important insights into self-organization processes prevalent in nature. 相似文献
312.
Hannah Yu Rachel N. Richey Marta Adeva Scott A. May Michael J. Coghlan 《Tetrahedron letters》2008,49(12):1915-1918
A stereoselective method for the preparation of dibenzoxapine containing tetrasubstituted exocyclic E-alkenes has been developed. The key reaction involves an intramolecular cyclocarbopalladation of alkynes to form a vinylpalladium species and subsequently coupling the vinylpalladium with methylboronic acid. The approach provides a straightforward method for the synthesis of tetrasubstituted exocyclic E-alkenes. 相似文献
313.
Cowpea mosaic virus capsid: a promising carrier for the development of carbohydrate based antitumor vaccines 总被引:1,自引:0,他引:1
Miermont A Barnhill H Strable E Lu X Wall KA Wang Q Finn MG Huang X 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(16):4939-4947
Immunotherapy targeting tumor cell surface carbohydrates is a promising approach for cancer treatment. However, the low immunogenecity of carbohydrates presents a formidable challenge. We describe here the enhancement of carbohydrate immunogenicity by an ordered display on the surface of the cowpea mosaic virus (CPMV) capsid. The Tn glycan, which is overexpressed on numerous cancer cell surfaces, was selected as the model antigen for our study. Previously it has been shown that it is difficult to induce a strong T cell-dependent immune response against the monomeric form of Tn presented in several ways on different carriers. In this study, we first synthesized Tn antigens derivatized with either a maleimide or a bromoacetamide moiety that was conjugated selectively to a cysteine mutant of CPMV. The glycoconjugate was then injected into mice and pre- and post-immune antibody levels in the mice sera were measured by enzyme-linked immunosorbant assays. High total antibody titers and, more importantly, high IgG titers specific for Tn were obtained in the post-immune day 35 serum, suggesting the induction of T cell-dependent antibody isotype switching by the glycoconjugate. The antibodies generated were able to recognize Tn antigens presented in their native conformations on the surfaces of both MCF-7 breast cancer cells and the multidrug resistant breast cancer cell line NCI-ADR RES. These results suggest that the CPMV capsid can greatly enhance the immunogenicity of weak antigens such as Tn and this can provide a promising tool for the development of carbohydrate based anti-cancer vaccines. 相似文献
314.
Hannah K. Box Tyler O. Howell William E. Kennon Griffin A. Burk Henry U. Valle T. Keith Hollis 《Tetrahedron》2017,73(16):2191-2195
The coupling of N-heterocyclic azoles (imidazoles, benzimidazoles, triazoles) to bromobenzenes (1,2-; 1,3-; or 1,4) in a step-wise, sequential manner was accomplished by manipulation of reaction time and stoichiometry, which provided straight-forward access to unsymmetrical bis(azolium) salts in only three isolation steps from commercially-available starting materials. Eight mono(azole) substituted bromobenzenes, four mono(azolium)bromobenzene salts, twelve unsymmetrical bis(azole)benzenes, and fourteen unsymmetrical bis(azolium) salts, which are precursors for pincer ligand complexes, are reported. 相似文献
315.
Enhancement of Solar Fuel Production Schemes by Using a Ru,Rh,Ru Supramolecular Photocatalyst Containing Hydroxide Labile Ligands
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Hannah Mallalieu Rogers Dr. Shamindri M. Arachchige Prof. Karen J. Brewer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):16948-16954
Polyazine‐bridged RuIIRhIIIRuII complexes with two halide ligands, Cl? or Br?, bound to the catalytically active Rh center are efficient single‐component photocatalysts for H2O reduction to H2 fuel, with the coordination environment on Rh impacting photocatalysis. Herein reported is a new, halide‐free RuIIRhIIIRuII photocatalyst with OH? ligands bound to Rh, further enhancing the photocatalytic reactivity of the structural motif. H2 production experiments using the photocatalyst bearing OH? ligands at Rh relative to the analogues bearing halides at Rh in solvents of varying polarity (DMF, CH3CN, and H2O) suggest that ion pairing with halides deactivates photocatalyst function, representing an exciting phenomenon to exploit in the development of catalysts for solar H2 production schemes. 相似文献
316.
Katy B. Wilson Hannah S. Nedzbala Spenser R. Simpson Megan N. Ericson Karl S. Westendorff Mahendra D. Chordia Diane A. Dickie W. Dean Harman 《Helvetica chimica acta》2021,104(10):e2100103
Reactions are described for complexes of the form WTp(NO)(PMe3)(η2-arene) and various amines, where the arene is benzene or benzene with an electron-withdrawing substituent (CF3, SO2Ph, SO2Me). The arene complex is first protonated to form an η2-arenium species, which then selectively adds the amine. The resulting η2-5-amino-1,3-cyclohexadiene complexes can then be subjected to the same sequence with a second nucleophile to form 3-aminocyclohexene complexes, where up to three stereocenters originate from the arene carbons. Alternatively, 1,3-cyclohexadiene complexes containing an ester group at the 5 position (also prepared from an arene) can be treated with acid followed by an amine to form trisubstituted 3-aminocyclohexenes. When the amine is primary, ring closure can occur to form a cis-fused bicyclic γ-lactam. Highly functionalized cyclohexenes can be liberated from the tungsten through oxidative decomplexation. The potential utility of this methodology is demonstrated in the synthesis of the alkaloid γ-lycorane. An enantioenriched synthesis of a lactam precursor to γ-lycorane is also described. This compound is prepared from an enantioenriched version of the tungsten benzene complex. Regio- and stereochemical assignments for the reported compounds are supported by detailed 2D-NMR analysis and 13 molecular structure determinations (SC-XRD). 相似文献
317.
Gagner J Johnson H Watkins E Li Q Terrones M Majewski J 《Langmuir : the ACS journal of surfaces and colloids》2006,22(26):10909-10911
Single bilayer membranes of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) were formed on micron thin-films of hydrophilized carbon nanotubes (CNT) by fusion of small unilamellar vesicles. The structure of the membrane was investigated using neutron reflectivity (NR). The underlying thin film of CNT was formed by chemical vapor deposition (CVD) in the presence of Fe catalyst, followed by reaction with 5 M nitric acid to render the film hydrophilic. We demonstrate that this platform lends support to homogeneous and continuous bilayer membranes that have promising applications in the fields of biomaterials, biosensors, and biophysics. 相似文献
318.
Vladimir I. Bakhmutov Aida Contreras-Ramirez Hannah Drake Hong-Cai Zhou 《Magnetic resonance in chemistry : MRC》2023,61(1):16-21
The phosphorus chemical shift anisotropies, 31PΔcs, and asymmetry parameters η were measured by the 31P{1H} NMR experiments in static and low-frequency spinning samples of the zirconium phosphates and phosphonates and also in the mixed Zr (IV)/Sn (IV) phosphate/phosphonate material. The data obtained have shown a 111 connectivity in the HPO4 and PO3 groups, which does not change at modification and intercalation of the materials. The 31PΔcs values of the phosphonate groups (43–49 ppm) significantly surpass the values characterizing the HPO4 groups (23–37 ppm). The 31P Δcs values obtained for the metal (IV) phosphates were discussed in terms of P-O distances. The 31P chemical shift anisotropy parameters can help at elucidation of local structures in phosphate and phosphonate materials. 相似文献
319.
Dr. Changkui Fu Dr. Baris Demir Sheilajen Alcantara Dr. Vinod Kumar Dr. Felicity Han Hannah G. Kelly Xiao Tan Ye Yu Weizhi Xu Dr. Jiacheng Zhao Dr. Cheng Zhang Dr. Hui Peng Prof. Cyrille Boyer Prof. Trent M. Woodruff Prof. Stephen J. Kent Prof. Debra J. Searles Prof. Andrew K. Whittaker 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(12):4759-4765
The conjugation of hydrophilic low-fouling polymers to therapeutic molecules and particles is an effective approach to improving their aqueous stability, solubility, and pharmacokinetics. Recent concerns over the immunogenicity of poly(ethylene glycol) has highlighted the importance of identifying alternative low fouling polymers. Now, a new class of synthetic water-soluble homo-fluoropolymers are reported with a sulfoxide side-chain structure. The incorporation of fluorine enables direct imaging of the homopolymer by 19F MRI, negating the need for additional synthetic steps to attach an imaging moiety. These self-reporting fluoropolymers show outstanding imaging sensitivity and remarkable hydrophilicity, and as such are a new class of low-fouling polymer for bioconjugation and in vivo tracking. 相似文献
320.
Dr. Nicolas G. Chabloz Dr. Margot N. Wenzel Hannah L. Perry Il-Chul Yoon Susannah Molisso Prof. Dr. Graeme J. Stasiuk Prof. Dr. Daniel S. Elson Prof. Dr. Anthony E. G. Cass Prof. Dr. James D. E. T. Wilton-Ely 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(46):10895-10906
The first example of an octadentate gadolinium unit based on DO3A (hydration number q=1) with a dithiocarbamate tether has been designed and attached to the surface of gold nanoparticles (around 4.4 nm in diameter). In addition to the superior robustness of this attachment, the restricted rotation of the Gd complex on the nanoparticle surface leads to a dramatic increase in relaxivity (r1) from 4.0 mm −1 s−1 in unbound form to 34.3 mm −1 s−1 (at 10 MHz, 37 °C) and 22±2 mm −1 s−1 (at 63.87 MHz, 25 °C) when immobilised on the surface. The one-pot synthetic route provides a straightforward and versatile way of preparing a range of multifunctional gold nanoparticles. The incorporation of additional surface units for biocompatibility (PEG and thioglucose units) and targeting (folic acid) leads to little detrimental effect on the high relaxivity observed for these non-toxic multifunctional materials. In addition to the passive targeting attributed to gold nanoparticles, the inclusion of a unit capable of targeting the folate receptors overexpressed by cancer cells, such as HeLa cells, illustrates the potential of these assemblies. 相似文献