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91.
Pol-Edern Le Renard Rolf LortzCarmine Senatore Jean-Philippe RapinFranz Buchegger Alke Petri-FinkHeinrich Hofmann Eric DoelkerOlivier Jordan 《Journal of magnetism and magnetic materials》2011,323(8):1054-1063
The biological and therapeutic responses to hyperthermia, when it is envisaged as an anti-tumor treatment modality, are complex and variable. Heat delivery plays a critical role and is counteracted by more or less efficient body cooling, which is largely mediated by blood flow. In the case of magnetically mediated modality, the delivery of the magnetic particles, most often superparamagnetic iron oxide nanoparticles (SPIONs), is also critically involved. We focus here on the magnetic characterization of two injectable formulations able to gel in situ and entrap silica microparticles embedding SPIONs. These formulations have previously shown suitable syringeability and intratumoral distribution in vivo. The first formulation is based on alginate, and the second on a poly(ethylene-co-vinyl alcohol) (EVAL). Here we investigated the magnetic properties and heating capacities in an alternating magnetic field (141 kHz, 12 mT) for implants with increasing concentrations of magnetic microparticles. We found that the magnetic properties of the magnetic microparticles were preserved using the formulation and in the wet implant at 37 °C, as in vivo. Using two orthogonal methods, a common SLP (20 W g−1) was found after weighting by magnetic microparticle fraction, suggesting that both formulations are able to properly carry the magnetic microparticles in situ while preserving their magnetic properties and heating capacities. 相似文献
92.
Sinoj Abraham Jae Ho Choi Chang‐Sik Ha Il Kim 《Journal of polymer science. Part A, Polymer chemistry》2007,45(23):5559-5572
The synthesis of new octafunctional alkoxyamine initiators for nitroxide‐mediated radical polymerization (NMRP), by the derivatization of resorcinarene with nitroxide free radicals viz TEMPO and a freshly prepared phosphonylated nitroxide, is described. The efficiency of these initiators toward the controlled radical polymerization of styrene and tert‐butyl acrylate is investigated in detail. Linear analogues of these multifunctional initiators were also prepared to compare and evaluate their initiation efficiency. The favorable conditions for polymerization were optimized by varying the concentration of initiators and free nitroxides, reaction conditions, etc., to obtain well‐defined star polymers. Star polystyrene thus obtained were further used as macro‐initiator for the block copolymerization with tert‐butyl acrylate. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5559–5572, 2007 相似文献
93.
Ricardo Godoy Lopez Christophe Boisson Franck D'Agosto Roger Spitz Fernande Boisson Didier Gigmes Denis Bertin 《Journal of polymer science. Part A, Polymer chemistry》2007,45(13):2705-2718
A synthetic method for the production of polyethylene (PE) chains carrying alkoxyamine end‐group has been proposed first by successfully reacting the well‐known 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO) and N‐(2‐methyl‐2‐propyl)‐N‐(1‐diethylphosphono‐2,2‐dimethylpropyl)‐N‐oxyl (commonly called SG1) stable radicals with dipolyethylenylmagnesium compounds to give PE‐TEMPO and PE‐SG1. Since the homolytic cleavage of these two macroalkoxyamines for the production of block copolymers using controlled radical polymerization would require temperatures higher than 160 °C, two original new nitroxides (4‐[(2,2‐dimethyl‐4‐(N‐tert‐Butyl‐N‐(1‐diethoxyphosphoryl‐2,2‐dimethylpropyl)aminoxy)‐4‐n‐butoxycarbonyl)butanoyloxyl]‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy, DD1) and 4‐[(2,2‐dimethyl‐4‐(N‐tert‐Butyl‐N‐(1‐diethoxyphosphoryl‐2,2‐dimethylpropyl)aminoxy)‐4‐phenyl) butanoyloxyl]‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy, DD2) containing a TEMPO moiety and incorporating an SG1‐based alkoxyamine (cleavage temperature: 60 °C) were then synthesized. NMR analyses showed that the resulting PE‐DD1 and PE‐DD2 were obtained using this functionalization strategy though with low to moderate yields (from 17% to 40%). PE‐DD2 (40% functionalization) was used under controlled radical polymerization conditions of n‐butyl acrylate. SEC analyses together with 1H NMR analysis showed that a poly(ethylene‐b‐n‐butyl acrylate) block copolymer was produced and that the polymerization proceeded under control. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2705–2718, 2007 相似文献
94.
N. Tiercelin V. Preobrazhensky V. Mortet A. Soltani P. Pernod 《Journal of magnetism and magnetic materials》2009,321(11):1803-1807
We report the use of a magnetic instability of the spin reorientation transition type to enhance the magnetoelectric sensitivity in magnetostrictive-piezoelectric structures. We present the theoretical study of a clamped beam resonant actuator composed of a piezoelectric element on a passive substrate actuated by a magnetostrictive nanostructured layer. The experiments were made on a polished 150 μm thick 18×3 mm2 lead zirconate titanate (PZT) plate glued to a 50 μm thick silicon plate and coated with a giant magnetostrictive nanostructured Nx(TbCo2 5nm/FeCo5nm) layer. A second set of experiments was done with magnetostrictive layer deposited on PZT plate. Finally, a film/film structure using magnetostrictive and aluminium nitride films on silicon substrate was realized, and showed ME amplitudes reaching 30 V Oe−1 cm−1. Results agree with analytical theory. 相似文献
95.
Tuba Erdogan Eda Gungor Hakan Durmaz Gurkan Hizal Umit Tunca 《Journal of polymer science. Part A, Polymer chemistry》2006,44(4):1396-1403
We prepared a novel miktoarm star copolymer with an azobenzene unit at the core via combination of atom transfer radical polymerization (ATRP) and nitroxide‐mediated free radical polymerization (NMP) routes. For this purpose, first, mikto‐functional initiator, 3 , with tertiary bromide (for ATRP) and 2,2,6,6‐tetramethylpiperidin‐1‐yloxy (TEMPO) (for NMP) functionalities and an azobenzene moiety at the core was synthesized. The initiator 3 thus obtained was used in the subsequent living radical polymerization routes such as ATRP of MMA and NMP of St, respectively, to give A2B2 type miktoarm star copolymer, (PMMA)2‐(PSt)2 with an azobenzene unit at the core with controlled molecular weight and low polydispersity (Mw/Mn < 1.15). The photoresponsive properties of 3 and (PMMA)2‐(PSt)2 miktoarm star copolymer were investigated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1396–1403, 2006 相似文献
96.
Gaël Laruelle Jeanne Franois Laurent Billon 《Macromolecular rapid communications》2004,25(21):1839-1844
Summary: Amphiphilic diblock copolymers consisting of a hydrophilic block, poly(acrylic acid), and a hydrophobic block, polystyrene, were synthesized by direct nitroxide‐mediated polymerization using the PS block as a macro‐initiator for the first time. Several techniques were used to characterize the amphiphilic block copolymers (size exclusion chromatography, NMR spectroscopy). The proposed method can lead to samples with a broad range of composition and molar mass. Preliminary studies of their self‐assembly in aqueous medium using fluorescence spectroscopy and small‐angle neutron scattering are presented.
97.
The Use of (−)‐Sparteine/Organolithium Reagents for the Enantioselective Lithiation of 7,8‐Dipropyltetrathia[7]helicene: Single and Double Kinetic Resolution Procedures 下载免费PDF全文
Dr. Julien Doulcet Dr. G. Richard Stephenson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51):18677-18689
The effect of organolithium reagent (RLi: R=nBu, iPr, sBu, tBu), solvent (diethyl ether, diethyl ether/THF and MTBE), and stoichiometry on the (?)‐sparteine‐mediated silylation of 7,8‐dipropyltetrathia[7]helicene shows that, unusually, substantially more than 0.5 equivalent of RLi (R=iPr, sBu, tBu) and a large excess of (?)‐sparteine (R=nBu, sBu) is often needed to achieve substantial conversions and good ee values. With nBuLi, however, just one equivalent of the organolithium reagent is sufficient to obtain high conversions. Our best results were obtained using the convenient tBuLi/(?)‐sparteine adduct with which the need for a high (?)‐sparteine/RLi ratio can be avoided. Single‐ and double‐kinetic resolution (KR) procedures give enantiopure samples of 2‐trimethylsilyl‐ and 2,13‐di(trimethylsilyl)‐7,8‐dipropyltetrathia[7]helicene and two‐step double‐KR combining (?)‐sparteine/sBuLi and chiral formamides affords the synthetically valuable 2‐formyl‐7,8‐dipropyltetrathia[7]helicene. This is the first use of (?)‐sparteine for the enantioselective lithiation of helicenes and the first report of tBuLi outperforming sBuLi in a (?)‐sparteine‐mediated procedure. 相似文献
98.
Sung Chul Hong Shijun Jia Mircea Teodorescu Tomasz Kowalewski Krzysztof Matyjaszewski Amy C. Gottfried Maurice Brookhart 《Journal of polymer science. Part A, Polymer chemistry》2002,40(16):2736-2749
Poly(n‐butyl acrylate)‐graft‐branched polyethylene was successfully prepared by the combination of two living polymerization techniques. First, a branched polyethylene macromonomer with a methacrylate‐functionalized end group was prepared by Pd‐mediated living olefin polymerization. The macromonomer was then copolymerized with n‐butyl acrylate by atom transfer radical polymerization. Gel permeation chromatography traces of the graft copolymers showed narrow molecular weight distributions indicative of a controlled reaction. At low macromonomer concentrations corresponding to low viscosities, the reactivity ratios of the macromonomer to n‐butyl acrylate were similar to those for methyl methacrylate to n‐butyl acrylate. However, the increased viscosity of the reaction solution resulting from increased macromonomer concentrations caused a lowering of the apparent reactivity ratio of the macromonomer to n‐butyl acrylate, indicating an incompatibility between nonpolar polyethylene segments and a polar poly(n‐butyl acrylate) backbone. The incompatibility was more pronounced in the solid state, exhibiting cylindrical nanoscale morphology as a result of microphase separation, as observed by atomic force microscopy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2736–2749, 2002 相似文献
99.
Dr. Céline Douat Dr. Christopher Aisenbrey Stéphanie Antunes Dr. Marion Decossas Dr. Olivier Lambert Dr. Burkhard Bechinger Dr. Antoine Kichler Dr. Gilles Guichard 《Angewandte Chemie (International ed. in English)》2015,54(38):11133-11137
Despite significant advances in foldamer chemistry, tailored delivery systems based on foldamer architectures, which provide a high level of control over secondary structure, are curiously rare among non‐viral technologies for transporting nucleic acids into cells. A potent pH‐responsive, bioreducible cell‐penetrating foldamer (CPF) was developed through covalent dimerization of a short (8‐mer) amphipathic oligourea sequence bearing histidine‐type units. This CPF exhibits a high capacity to assemble with pDNA and mediates efficient delivery of nucleic acids into the cell. Furthermore, it does not adversely affect cellular viability and was shown to compare favorably with a cognate peptide transfection agent based on His‐rich sequences. 相似文献
100.
Poly-substituted dihydrofurans and tetrahydrofurans have been synthesized through polymer-supported selenium-induced intramolecular electrophilic cyclization, followed by selenoxide syn-elimination or novel nucleophilic substitution cleavage of selenium resin with good yields and purities. 相似文献