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排序方式: 共有246条查询结果,搜索用时 46 毫秒
41.
Audrey Sassolas Loïc J. Blum Béatrice D. Leca-Bouvier 《Analytical and bioanalytical chemistry》2009,394(4):971-980
Performant reagentless electrochemiluminescent (ECL) (bio)sensors have been developed using polymeric luminol as the luminophore.
The polyluminol film is obtained by cyclic voltammetry (CV) on a screen-printed electrode either in a commonly used H2SO4 medium or under more original near-neutral buffered conditions. ECL responses obtained after performing polymerization either
at acidic pH or at pH 6 have been compared. It appears that polyluminol formed in near-neutral medium gives the best responses
for hydrogen peroxide detection. Polymerization at pH 6 by cyclic voltammetry gives a linear range extending from 8 × 10−8 to 1.3 × 10−4 M H2O2 concentrations. Based on this performant sensor for hydrogen peroxide detection, an enzymatic biosensor has been developed
by associating the polyluminol film with an H2O2-producing oxidase. Here, choline oxidase (ChOD) has been chosen as a model enzyme. To develop the biosensor, luminol has
been polymerized at pH 6 by CV, and then an enzyme-entrapping matrix has been formed on the above modified working electrode.
Different biological (chitosan, agarose, and alginate) and chemical (silica gels, photopolymers, or reticulated matrices)
gels have been tested. Best performances have been obtained by associating a ChOD-immobilizing photopolymer with the polyluminol
film. In this case, choline can be detected with a linear range extending from 8 × 10−8 to 1.3 × 10−4 M.
This paper is based on the results presented in a poster that received a Poster Award on the occasion of XIII International
Symposium on Luminescence Spectrometry in Bologna, Italy, on September, 7th-11th, 2008. 相似文献
42.
通过电化学聚合法制备了3, 6-(二噻吩基)-9-(二茂铁甲酸己酯基)-咔唑(BTC-H-Fc)与3, 4-乙烯二氧噻吩(EDOT)不同摩尔比下的共聚物,并运用电化学、傅里叶变换红外(FT-IR)光谱及光谱电化学对其结构与性能进行了表征。研究结果表明所得共聚物均能显示良好的电化学特性,光谱电化学测试结果表明,当摩尔浓度比为1时, P(BTC-H-Fc:EDOT)-1中性态下表现浅绿色,且随着施加电压增加转变为绿色和紫色; P(BTC-H-Fc:EDOT)-4则显示了最丰富的颜色,可在中性态的红褐色、棕黄色、绿色、蓝色和紫色五种颜色之间可逆变换;当摩尔比继续增加时, P(BTC-H-Fc:EDOT)-8可以显示红褐色、灰黑色、蓝绿色和天空蓝四种颜色。另外,三种摩尔比的聚合物薄膜还具有不错的光学对比度,转换响应时间及着色效率,该性能为其在电致变色器件的应用提供了潜力。 相似文献
43.
The integration of multiscale and multicomponent of molecules and nanoparticles into thin films for applications requires the abilities of controlled their processing and assembly,which has been an great challenge because of the difficulty in manipulating the various materials such as small molecules,complexes,polymers,and inorganic nanomaterials through synergetic combinations of chemical or physical fabrications.Eletropolymerization is of great significance to fabricate polymeric film materials straight on the conductive substrates with tunable morphologies and thicknesses.However,unlimited electrochemical reactions(polymerization)have been usually leading to disadvantageous in ill-defined structure and highly doped state.Thanks to finding of exceptional electrochemical reaction(oligomerization)of N-alkylcarbazole,electrochemical layer by layer assembly has emerged as a promising strategy for a wide library of applications.The capability of this strategy can manipulate various molecules and nanoparticles into the scale and component controllable thin films.Unlike other electropolymerizable precursors such as aniline and thiophene,the resulting di-N-alkylcarbazole is transparent in the visible light region and thus does not impair the intrinsic properties of the components in the film.This account highlights of the typical findings in investigating both single-and multi-components thin films as a forum for discussing new opportunities in exploiting novel designs and applications of optical thin films. 相似文献
44.
We report the modification of various electrode surfaces with electropolymerized Magnus' green salts, [Pt(NH3)4 · PtCl4]
n
and [Pt(NH3)4 · PtCl6]
n
. The modified electrodes were prepared by cyclic scanning of the electrode potential in an aqueous solution containing Pt(NH3)4
2+ and PtCl4
2− or PtCl6
2− and the supporting electrolyte. The conditions for the film deposition were studied in detail. Several surface analytical
techniques, including micro-Raman scattering and X-ray diffraction, were employed to characterize the modifier film. The electrochemical
behavior of the modified electrode was studied in detail and the modified electrodes display very good electrocatalytic activity
in the oxidation of ascorbic acid, hydrogen peroxide, thiosulfate, and especially nitric oxide.
Received: 22 April 1999 / Accepted: 30 June 1999 相似文献
45.
Edward Szlyk Stanislaw Biniak Erik Larsen 《Journal of Solid State Electrochemistry》2001,5(3):221-226
The electrochemical properties and catalytic activity of a Co(II) complex with the optically active Schiff base derived from
(1R,2R)-(–)-cyclohexanediamine and salicylaldehyde have been studied in non-aqueous solutions. When dissolved in deoxygenated non-aqueous
solutions, the complex exhibits reversible redox properties for the Co(II)/Co(III) couple. Electrochemical reduction of oxygen
and oxidation of cobalt(II) was observed on cyclic voltammograms of solutions containing both dioxygen and the Schiff base-cobalt(II)
complex. An anodically formed film on a platinum electrode, studied by means of X-ray photoelectron spectroscopy, revealed
the presence of the oxidized Co(III) species. Cyclic voltammetry of oxygenated solutions examined after a period of time indicates
an electrochemical activity of coordinated superoxo/peroxo species in the 0.7–1.1 V potential range. In the presence of 4-methyl-1-cyclohexene
the cyclic voltammetry curves reveal changes similar to those caused by the removal of oxygen. The GC-MS technique was used
to identify some of the products formed by the catalytic oxidation of cyclohexene and 4-methyl-1-cyclohexene.
Electronic Publication 相似文献
46.
An Electrochemical Sensor Based on Electropolymerization of ß‐Cyclodextrin and Reduced Graphene Oxide on a Glassy Carbon Electrode for Determination of Neonicotinoids 下载免费PDF全文
《Electroanalysis》2018,30(9):1918-1928
An electrochemical sensor of glassy carbon electrode modified with reduced graphene oxide and β‐cyclodextrin (GCE/rGO/β‐CD) was developed as an effective alternative in the determination of neonicotinoid insecticides, imidacloprid, clothianidin and thiamethoxam, in honey samples. The peak current variation obtained with the proposed sensor was higher compared to the bare GCE in all the analytes. In the determination of imidacloprid the response increased by 1300 %, clothianidin by 670 % and thiametoxam by 630 %. In addition, the optimization of the experimental conditions provided the construction of a sensor with greater sensitivity. The study of interferers showed that inorganic ions (Ca2+, Mg2+, Fe2+, K+, Na+, e NH4+) and other insecticides (acetamiprid and dinotefuran) did not influence the reduction of imidacloprid, clothianidin and thiamethoxam. The determination of imidacloprid, clothianidin and thiamethoxam in honey samples exhibited recovery values within the EPA range (between 107.75 and 116 %). In conclusion, the developed sensor GCE/rGO/β‐CD proved to be an effective alternative in the determination of neonicotinoid insecticides in honey samples. 相似文献
47.
Rodica E. Ionescu Khalil Abu-Rabeah Serge Cosnier Robert S. Marks 《Electrochemistry communications》2005,7(12):1277-1282
A novel pyrrole-alginate was synthesized providing a gel by Ca2+ cross-linking. The subsequent in situ electrochemical polymerization of the linked pyrrole groups at 0.93 V led to the formation of a composite polypyrrole–gel matrix exhibiting a greater enzyme retention as well as increased alginate stability towards the destructive effect of phosphate anions unlike the natural alginate gel. The presence of the electropolymerized chains was clearly indicated by the decrease of the permeability when compared to natural alginate gel, namely 2.7 × 10−2 and 3.65 × 10−1 cm s−1 respectively, using as an electroactive permeate, hydroquinone. Moreover, the analytical performance of glucose oxidase-based composite alginate for the determination of glucose was determined. 相似文献
48.
Condensation of pyrrole with 2-fluorenecarboxaldehyde yields meso-tetrafluorenylporphyrin as a new building block. After ruthenium insertion, oxidative electropolymerization of tetrafluorenylporphyrinruthenium (II) carbonyl complexes can be used to coat Pt electrodes with polymeric films. These insoluble polymeric materials are able to catalyze the heterogeneous cyclopropanations and 2,3 sigmatropic rearrangements with ethyl diazoacetate after being removed from the electrode. 相似文献
49.
Shen-Ming Chen Ying-Lu Chen R. Thangamuthu 《Journal of Solid State Electrochemistry》2007,11(10):1441-1448
Stable electroactive iron tetra(o-aminophenyl)porphyrin (FeTAPP) films are prepared by electropolymerization from aqueous solution by cycling the electrode
potential between −0.4 and 1.0 V vs Ag/AgCl at 0.1 V s−1. The cyclic voltammetric response indicates that polymerization takes place after the oxidation of amino groups, and the
films could be produced on glassy carbon (GC) and gold electrodes. The film growth of poly(FeTAPP) was monitored by using
cyclic voltammetry and electrochemical quartz crystal microbalance. The cyclic voltammetric features of Fe(III)/Fe(II) redox
couple in the film resembles that of surface confined redox species. The electrochemical response of the modified electrode
was found to be dependent on the pH of the contacting solution with a negative shift of 57 mV/pH. The electrocatalytic behavior
of poly(FeTAPP) film-modified electrode was investigated towards reduction of hydrogen peroxide, molecular oxygen, and chloroacetic
acids (mono-, di-, and tri-). The reduction of hydrogen peroxide, molecular oxygen, and dichloroacetic acid occurred at less
negative potential on poly(FeTAPP) film compared to bare GC electrode. Particularly, the overpotential of hydrogen peroxide
was reduced substantially. The O2 reduction proceeds through direct four-electron reduction mechanism. 相似文献
50.
《Electroanalysis》2004,16(4):289-297
The polymer film of N,N‐dimethylaniline (DMA) is deposited on the electrochemically pretreated glassy carbon (GC) electrode by continuous electrooxidation of the monomer. This poly N,N‐dimethylaniline (PDMA) film‐coated electrode can be used as an amperometric sensor of ascorbic acid (AA). The polymer film (thickness (?): 0.3±0.02 μm) having positive charge in its backbone attracts the anionic species AA. Thus, the anodic peak potential (350 mV vs. Ag|AgCl|NaCl(sat)) for the oxidation of AA at the bare electrode is largely shifted to the negative value (150 mV) at this electrode. The PDMA film‐coated electrode is stable in acidic, alkaline and neutral media and can sense AA at different pH's. The diffusion coefficients of AA in solution (D) and in film (Ds) were estimated by rotating disk electrode voltammetry: D=(5.5±0.1)×10?6 cm2 s?1 and Ds=(6.3±0.2)×10?8, (6.0±0.2)×10?8 and (4.7±0.2)×10?8 cm2 s?1 for 0.5, 1.5 and 3.0 mM AA, respectively. A permeability of AA through the PDMA film was found to decrease with increasing the concentration of AA in the solution. In the chronoamperometry, the current response for the oxidation of AA at different times elapsed after potential‐step application is linearly increased with the increase in AA concentration in a wide range of its concentration from 25 μM to 1.65 mM. In the hydrodynamic amperometry, a successive addition of 10 μM AA caused the successive increase in current response with equal amplitude and the sensitivity was calculated as 0.178 μA cm?2 μM?1. So, the fouling of the electrode surface caused by the oxidized product of AA is markedly eliminated at this PDMA film‐coated electrode. A flow injection analysis based on the present electrode was performed to estimate the concentration of vitamin C in fruit juice. 相似文献