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121.
0IntroductionStudies of direct electrochemistry of proteins orenzymes at electrodes can serve as a basis for build-ing electrochemical biosensors,enzymatic bioreactors,and biomedical devices[1].This approach simplifiessuch devices without using mediators and is of partic-ular significance for fabricating the third generationbiosensors[2].For example,if a protein or enzyme im-mobilized on electrode surface is capable of directelectron transfer without loss of bioactivities,it can beused in the … 相似文献
122.
Application of L-Cysteine-Capped ZnS Nanoparticles in the Determination of Nucleic Acids Using the Resonance Light Scattering Method 总被引:2,自引:0,他引:2
Yongxin?LiEmail author Jinlong?Chen Shujuan?Zhuo Yuqin?Wu Changqin?Zhu Lun?Wang 《Mikrochimica acta》2004,146(1):13-19
Nanometer-sized L-cysteine-capped ZnS particles were synthesized by a colloidal aqueous method. The functionalized nanoparticles are water-soluble and suitable for biological applications. In Tris-HCl buffer solution, nucleic acids combine with cysteine-capped nano-ZnS particles by intermolecular forces to form larger nanoparticles. There are two resonance light scattering peaks at 304.5nm and 373.8nm, respectively. The enhanced RLS is related to the concentration of nucleic acids in the range of 0.04 to 1.2µgmL–1 for calf thymus DNA and 0.2 to 1.0µgmL–1 for fish sperm DNA. The detection limits (3) are 19ngmL–1 for calf thymus DNA and 23ngmL–1 for fish sperm DNA, respectively. Four synthetic samples were analyzed satisfactorily. 相似文献
123.
Nanocomposites of poly(vinyl alcohol)/silica nanoparticles (PVA-SNs) were prepared by in-situ radical copolymerization of vinyl silica nanoparticles functionalized by vinyltriethoxysilane (VTEOS) and vinyl acetate with benzoyl peroxide (BPO, i.e., initiator), subsequently saponified via direct hydrolysis with NaOH solution. The resulting vinyl silica nanoparticles, PVA-SNs were characterized by means of fourier transformation spectroscopy (FTIR), transmission electron microscopy (TEM) and the elemental analysis method. Effects of silica nanoparticles on viscosity and alcoholysis of PVA-SNs were studied by a ubbelohode capillary viscometer and the back titration method. The morphological structure of PVA-SN films was investigated by scanning electron microscopy (SEM). Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile test were used to determine the thermal and mechanical properties of PVA-SN films. The results indicated that the content of vinyl groups on the surface of the vinyl silica nanoparticles was up to 3.02 mmol/g and vinyl silica nanoparticles had been successfully copolymerized with vinyl acetate. Furthermore, compared to pure PVA, silica nanoparticles bonded with polymer matrix in a low concentration affected the viscosity and alcoholysis of the PVA-SNs materials. At the same time, it resulted in the improvement of the thermal and mechanical properties of the PVA-SN materials due to a strong interaction between silica nanoparticles and the polymer matrix via a covalent bond. It could be found that the optical clarity of the membrane was changed through UV-Vis absorption spectrum due to the introduction of silica nanoparticles. 相似文献
124.
Selective hydrogenation of α,β‐unsaturated carbonyls into saturated carbonyls is important to obtain remunerative products. However, it is still a challenge to achieve high activity and selectivity under mild conditions. Herein, Pd, Ir and bimetallic Pd‐Ir nanoparticles were uniformly deposited with high dispersity on the surface of SiC by a facile impregnation method, respectively. The as‐prepared Pd/SiC catalysts efficiently hydrogenate cinnamaldehyde to hydrocinnamaldehyde at room temperature and atmospheric pressure, and the activity of Pd/SiC is observed further enhanced by adding Ir component (conversion of 100%). In addition, the dependence of Pd‐Ir catalyst activity on Pd/Ir molar ratio confirms a synergistic effect between Ir and Pd, which originates from the electron transfer between Pd and Ir. 相似文献
125.
This work describes an improved seed-mediated growth approach for the direct attachment and growth of mono-dispersed gold nanoparticles on nanostructured indium tin oxide (ITO) surfaces. It was demonstrated that, when the seeding procedure of our previously reported seed-mediated growth process on an ITO surface was modified, the density of gold nanospheres directly grown on the surface could be highly improved, while the emergence of nanorods was restrained. By field emission scanning electron microscopy (FE-SEM) and cyclic voltammetry, the growth of gold nanoparticles with increasing growth time on the defect sites of nanostructured ITO surface was monitored. Using a [Fe(CN)6]3−/[Fe(CN)6]4− redox probe, the increasingly facile heterogeneous electron transfer kinetics resulting from the deposition and growth of gold nanoparticle arrays was observed. The as-prepared gold nanoparticle arrays exhibited high catalytic activity toward the electrooxidation of nitric oxide, which could provide electroanalytical application for nitric oxide sensing. 相似文献
126.
A. L. Stroyuk A. I. Kryukov S. Ya. Kuchmii V. D. Pokhodenko 《Theoretical and Experimental Chemistry》2005,41(2):67-91
The appearance of quantum size effects in ultradisperse semiconductors, their quantitative analysis, and their effect on the absorption of light and on the photophysical (vibrational relaxation of photogenerated “hot” charge carriers, band-band and “defect” luminescence) and certain primary photochemical processes (the accumulation of excess negative charge by the semiconductor nanoparticles, interphase electron transfer, etc.) are discussed.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 2, pp. 67–87, March–April, 2005. 相似文献
127.
Rui M. Almeida Ana C. Marques Maurizio Ferrari 《Journal of Sol-Gel Science and Technology》2003,26(1-3):891-896
The present paper is focused on multilayer Er3+-doped silica-titania planar waveguides, co-doped with silver, which were prepared by spin-coating on silica glass, or buffered single crystal silicon substrates. The single layer thickness (0.4 m) and refractive index (1.60–1.63) were measured by spectroscopic ellipsometry at 715 nm. The thickness of the waveguides (measured by mechanical profilometry) was 1 m and their optical propagation losses were measured at different laser wavelengths (488 nm, 514 nm and 633 nm), exhibiting an approximately Rayleigh-like behavior. The thermal precipitation of silver nanocrystallites was achieved, both in air and under a controlled atmosphere (dry nitrogen) and these were characterized by visible absorption spectroscopy, which clearly showed the development of a plasmon absorption band near 415 nm, by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The Er3+ metastable level lifetimes for the emission at ca. 1.54 m were found to be ca. 4–6 ms, for Er3+ concentrations varying between 0.2–2.0 mol% (or (0.4–4.4) × 1020 ions/cm3), but no significant variation was observed with the Ag concentration added (up to 2.5 mol%). 相似文献
128.
Carlos Rodríguez-Abreu Massimo Lazzari Dharmesh Varade Masaya Kaneko Kenji Aramaki Manuel Arturo López Quintela 《Colloid and polymer science》2007,285(6):673-680
The structure and rheological properties of a poly(dimethylsiloxane)-graft-poly(oxyethylene) copolymer at high concentrations
in block-selective solvents were studied by small-angle X-ray scattering (SAXS) and rheometry. Analysis of SAXS data indicates
that quasispherical, reverse micellar aggregates (with no ordered packing) are present in concentrated solutions of the copolymer
in nonpolar solvents, and that upon addition of water, the size of such aggregates increases due to the solubilization inside
the micellar cores. The viscosity of concentrated polymer solutions increases exponentially as water is added, and finally,
viscoelastic, gel-like behavior is found in the vicinity of the phase separation limit. It was found that small silver nanoparticles
with an average diameter of ≈3 nm can be synthesized inside the copolymer aggregates without the need of a reducing agent;
namely, particles embedded in a viscoelastic matrix are obtained. The synthesis seems to follow first-order kinetics.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
129.
A sandwiched structure of CdS/Ag/ZnO nanorod photoanode exhibits greatly enhanced photoelectrochemical activity for solar hydrogen generation, due to synergistic effect of CdS nanocrystallites and plasmonic Ag nanoparticles for the enhanced optical absorption and the promoted charge carrier separation. 相似文献
130.
Fu-Ken Liu 《Analytica chimica acta》2005,528(2):249-254
This paper demonstrates that capillary electrophoresis (CE) can be employed for characterizing the sizes of nanometer-scale gold particles. We characterized the gold nanoparticles by effecting CE separation using a buffer of SDS (70 mM) and 3-cyclohexylamino-1-propanesulfonic acid (CAPS; 10 mM) at pH 11.0 and an applied voltage of 18 kV and obtained a linear relationship (R2 > 0.99) between electrophoretic mobilities and size for nanoparticles whose diameters fall in the regime from 5.0 ± 0.5 to 41.2 ± 3.3 nm; the relative standard deviations of these electrophoretic mobilities are <0.8%. We evaluated the feasibility of employing these separation conditions for the size characterization by of gold nanoparticle samples that were synthesized by a rapid microwave heating method. We confirmed that this CE method is a valid one for size characterization by comparing the results obtained by CE with those provided by scanning electron microscopy (SEM); a good correlation exists between these two techniques. Our results demonstrate that CE can be employed to accelerate the analysis of the sizes of nanomaterials. 相似文献