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991.
The formation of covalently linked composites of multi–walled carbon nanotubes (MWCNT) and glucose oxidase (GOD) with high-function
density for use as a biosensing interface is described. The reaction intermediates and the final product were characterized
by using FT–IR spectroscopy, and the MWCNT-coated GOD nanocomposites were examined by atomic force microscopy (AFM) and transmission
electron microscopy (TEM). Interestingly, it was found that the GOD–MWCNT composites are highly water soluble. Electrochemical
characterization of the GOD–MWCNT composites that were modified on a glassy carbon electrode shows that the covalently linked
GOD retains its bioactivity and can specifically catalyze the oxidation of glucose. The oxidation current shows a linear dependence
on the glucose concentration in the solution in the range of 0.5–40 mM with a detection limit of 30 μM and a detection sensitivity
of 11.3 μA/mMcm2. The present method may provide a way to synthesize MWCNT related composites with other biomolecules and for the construction
of enzymatic reaction-based biofuel cells and biosensors.
Supported by grants from the National Natural Science Foundation of China (NSFC, No. 20125515; 90206037; 20375016) and the
Natural Science Foundation of Jiangsu Province (Grant No. BK 2004210) 相似文献
992.
交联聚磷酸酯的合成及其释药性能研究 总被引:6,自引:0,他引:6
以(i-Bu)3Al为引发剂研究了2-氢-2-氧-1,3,2二氧五环磷酸酯,2-氢-2-氧-1,3,2-二氧六联药物载体,要用单层骨架片、双层骨架片和夹心片 药方式,对抗肿瘤药物5-氟尿嘧啶进行了控制释放,获得了较好的释药效果。 相似文献
993.
High density (98% of theoretical) was achieved at 900°C for an all-alkoxide derived bulk celsian gel prior to crystallisation. TEM indicated that crystallisation was dominated by volume nucleation and growth of hexagonal disc shaped hexacelsian. Kinetic studies using SEM indicate a maximum nucleation rate at 980°C and an activation energy for crystal growth of 566 KJ/mol. The high rates of densification and of nucleation are attributed to the high OH content in the gel-derived glass. 相似文献
994.
A rapid method for the derivatization of phenolic antioxidants using microwave irradiation has been developed. Six antioxidatively active phenolic components of wines and fruits, namely gallic acid, gentisic acid, vanillic acid, caffeic acid, ferulic acid and p-coumaric acid were used in the model study. The solution of phenolic acids was evaporated to dryness on a rotary evaporator followed by further drying under microwave irradiation (600 W, 30 s). The resultant residue was dissolved in pyridene and treated with bis(trimethylsilyl)acetamide while irradiated by microwave using high power for 30 s. Controlled reaction was carried out employing bis(trimethylsilyl)trifluoroacetamide under conventional heating for 30 min. The trimethylsilyl derivatives were identified and quantified on a gas chromatography/mass selective detector. The mass spectral fragmentation patterns of the derivatives obtained by microwave irradiation were identical to those prepared by heating. The yields of microwave-assisted silylation were comparable to those from conventional heating. The rsd were less than 8% for six replicates. The linearity in wine matrix was nearly perfect. This method is a useful protocol to examine the phenolic constituents in wines and agricultural products. 相似文献
995.
This study describes a new methodology by which the concentrations of non-protein (NP) thiols glutathione (GSH), cysteine (CSH), N-acetylcysteine (AcCSH), and protein (P) thiols (PSH), as well as the contribution of these components to symmetric and mixed disulfides (NPSSR, NPSSC, NPSSCAc, PSSR, PSSC, PSSCAc, PSSP) can reliably be measured. The methodology consists of a strict sequence of methods which are applied to every sample. Free thiols at any given state of the procedure are measured by Ellmans assay, the CSH fraction is measured by its unique response in the ninhydrin assay, AcCSH is selectively measured with ninhydrin after enzymatic deacylation, proteins are separated from non-protein thiols/disulfides by precipitation with trichloroacetic or perchloric acid, disulfides are reduced into free thiols with borohydride, mixed disulfides between a protein and a non-protein component are measured by extracting the non-protein thiol from the protein pellet after borohydride treatment, and protein thiols/disulfides are measured after resolubilization of the protein pellet.When this method was applied to animal and fungal tissue, new molecular indicators of the thiol redox state of living cells were identified. The findings of the present study clearly show that the new parameters are very sensitive indicators of redox state, while at the same time the traditional parameters GSH and GSSG often remain constant even upon dramatic changes in the overall redox state of biological tissue. Therefore, unbiased assessment of the redox state also requires explicit measurement of its most sensitive thiol indicators.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material. 相似文献
996.
Chiral α,ω-diesters react under high-pressure conditions (10 kbar) with α,ω-diamines to give chiral cyclic tetraamides of C2-symmetry. The complexation properties of tetraamides towards alkali metal cations (Li+, Na+, K+, Rb+ and Cs+) were estimated on the basis of ESI-MS spectra. 相似文献
997.
碳酸自由基、硝酸自由基、磷酸自由基和硫酸自由基是化学反应的重要中间体,都具有氧化性,对污染物在自然和人为环境中的迁移转化会产生重要的影响.文中较为详细地介绍这几种自由基的电极电位、产生方式、检测方法及与有机物的反应方式.总结四种自由基的特性及与有机物的反应方式可发现,四种自由基和羟自由基电极电位不同,导致它们和有机物反应速率的不同;碳酸自由基并不是羟自由基去除剂,对于一些容易被氧化的化合物,碳酸自由基氧化效果比羟自由基好;四种自由基均可由羟自由基转化而来,并且这四种自由基和羟自由基与有机物反应方式基本一致,都通过电子转移、夺氢和加成的方式进行.可以预测四种自由基和羟自由基降解有机物的机理将非常相似,今后应研究四种自由基与羟自由基相互转化的规律,以及与代表性有机物的反应机理. 相似文献
998.
999.
Preparation and characterization of nitrogen-doped TiO2 photocatalyst in different acid environments
Ye Cong Ling Xiao Jinlong Zhang Feng Chen Masakazu Anpo 《Research on Chemical Intermediates》2006,32(8):717-724
Nitrogen-doped TiO2 powders were successfully prepared by a wet method, i.e., a micro-emulsion-hydrothermal method, in different acid environments.
Several characterization techniques, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse
reflectance spectra, were combined to determine the crystal phase, concentration and chemical states of the nitrogen doped
in TiO2. The high photocatalytic activity of the nitrogen-doped TiO2 was evaluated through the decomposition of rhodanmine B under visible light irradiation. It was suggested that the doped
nitrogen formed oxynitride (NO) and produced impurity states at higher above the valence band of TiO2. Therefore, the nitrogen doping could enhance the response of photocatalyst to the visible light and improve the photocatalytic
activity because of the narrowing of band gap of TiO2. 相似文献
1000.
YiJianCHEN GuiYingXU ShiLingYUAN HaiYingSUN 《中国化学快报》2005,16(5):688-690
Molecular dynamics (MD) simulation are used to study the properties of gemini surfactant of ethyl-α,ω-bis(dodecyldimethylammonium bromide) (C12C2C12) and dodecyl-trimethylammonium bromide (DTAB) at the air/water interface, respectively. In the two systems,t he surfactant concentrations are both 28 wt.%, and other conditions are also the same. After reaching the thermodynamic equilibrium, the concentration profiles, the radial distributions functions (RDF) and the mean squared displacement (MSD) are investigated. The results reveal that the surface activity of C12C2C12 surfactant is higher than DTAB surfactant. 相似文献