322 resultados para amphotericin B


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Advances in tissue engineering require biofunctional scaffolds that can provide not only physical support for cells but also chemical and biological cues needed in forming functional tissues. To achieve this goal, a novel RGD peptide grafted poly(ethylene glycol)-b-poly(L-lactide)-b-poly(L-glutamic acid) (PEG-PLA-PGL/RGD) was synthesized in four steps (1) to prepare diblock copolymer PEG-PLA-OH and to convert its -OH end group into -NH2 (to obtain PEG-PLA-NH2), (2) to prepare triblock copolymer PEG-PLA-PBGL by ring-opening polymerization of NCA (N-carboxyanhydride) derived from benzyl glutamate with diblock copolymer PEG-PLA-NH2 as macroinitiator, (3) to remove the protective benzyl groups by catalytic hydrogenation of PEGPLA-PBGL to obtain PEG-PLA-PGL, and (4) to react RGD (arginine-glycine-(aspartic amide)) with the carboxyl groups of the PEG-PLA-PGL. The structures of PEG-PLA-PGL/RGD and its precursors were confirmed by H-1 NMR, FT-IR, amino acid analysis, and XPS analysis. Addition of 5 wt % PEG-PLA-PGL/RGD into a PLGA matrix significantly improved the surface wettability of the blend films and the adhesion and proliferation behavior of human chondrocytes and 3T3 cells on the blend films. Therefore, the novel RGD-grafted triblock copolymer is expected to find application in cell or tissue engineering.

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近年来,有机薄膜晶体管(OTFTs)因其成本低、加工简便,特别适用于制备大面积柔性器件而引起人们的广泛关注[1].并苯类化合物和噻吩衍生物是目前最重要的两类高迁移率OTFT材料.由并五苯制备的多晶OTFTs器件迁移率可达到5cm2/(V·s)[2];烷基修饰齐聚噻吩的场致迁移率也可达到非晶硅[0·1~1cm2/(V·s)]的水平[3].但是,这两类材料具有较窄的能隙和较高的最高被占分子轨道(HOMO)能级,容易与空气中的氧气和水发生作用,所制备的器件在空气中衰减较快,并且并苯类化合物对光也非常敏感,限制了其应用范围[4~6].因此,制备稳定的高迁移率有机半导体材料是有机光电子研究领域的重要课题之一.制备稳定的高迁移率有机半导体材料的途径包括用较稳定的芳香基团对噻吩齐聚物进行封端,以增大能隙和降低HOMO能级[7].菲类化合物是并苯类化合物的异构体,具有较好的光稳定性[8].[3,2-b]并二噻吩是一种平面稠环分子,与2,2′-二噻吩相比,HOMO能级相对降低,因而具有相对好的稳定性[9].本文合成了2,5-二(2-菲基)-[3,2-b]并二噻吩(PhTT),表征了其基本的物理和化学性质,制备了相应的有机薄膜晶...

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In the title compound, C9H8N2O2, two crystallographically independent molecules form a dimer structure, in which two N-H center dot center dot center dot N hydrogen bonds generate an intermolecular R-2(2)( 8) ring.

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In the asymmetric unit of the title compound, C9H8N2O2, there are two crystallographically independent molecules, each of which forms a dimer, via N-H center dot center dot center dot O hydrogen bonds, with an inversion-related molecule.

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The surface morphology and crystallization behavior of a weakly segregated symmetric diblock copolymer, poly(styrene-b-6-caprolactone) (PS-b-PCL), in thin films were investigated by optical microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy (AFM). When the samples were annealed in the molten state, surface-induced ordering, that is, relief structures with uniform thickness or droplets in the adsorbed monolayer, were observed depending on the annealing temperature. The polar PCL block preferred to wet the surface of a silicon wafer, while the PS block wet the air interface. This asymmetric wetting behavior led to the adsorbed monolayer with a PCL block layer having a thickness of around 4.0 nm. The crystallization of PCL blocks could overwhelm the microphase-separated structure because of the weak segregation. In situ observation of crystal growth indicated that the nucleation process preferred to occur at the edge of the thick parts of the film, that is, the relief structures or droplets. The crystal growth rate was presented by the time dependence of the distance between the tip of crystal clusters and the edge. At 22 and 17 degreesC, the average crystal growth rates were 55 +/- 10 and 18 +/- 4 nm/min, respectively.

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Rhodamine B (RB)-doped organic-inorganic silica films and their patterning were fabricated by a sol-gel process combined with a soft lithography. The resulted film samples were characterized by atomic force microscope (AFM), optical microscope and UV/Vis absorption and photoluminescence excitation and emission spectra. The effects of the concentration of the RB dye and heat treatment temperature on the optical properties of the hybrid silica films have been studied. Four kinds of patterning structures with film line widths of 5, 10, 20 and 50 mum have been obtained by micromolding in capillaries by a soft lithography technique. The RB-doped hybrid silica films present a red color, with an excitation and emission bands around 564 and 585 mum, respectively. With increasing the RB concentration, the emission intensity of the RB-doped hybrid silica films increases and the emission maximum presents a red shift. The emission intensity of the films decreases with increasing the heat treatment temperatures.

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The experimental data of phase diagrams for both polyethylene oxide/poly(ethylene oxide-b-dimethylsiloxane) binary and toluene/polyethylene oxide/poly(ethylene oxide-b-dimethylsiloxane) ternary polymer-containing systems was obtained at atmosphere pressure by light scattering method. The critical points for some pre-selected compositions and the pressure effect on the phase transition behavior of ternary system were investigated by turbidity measurements. The chosen system is a mixture of ternary which is one of the very few abnormal polymer-containing systems exhibiting pressure-induced both miscibility and immiscibility. This unusual behavior is related to the toluene concentration in the mixtures. The effect of toluene on the phase transition behavior of the ternary polymer-containing mixture was traced. Such behavior can make it possible to process composite materials from incompatible polymers.