The Experts below are selected from a list of 42210 Experts worldwide ranked by ideXlab platform
Tebello Nyokong - One of the best experts on this subject based on the ideXlab platform.
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Electrode modification using iron metallophthalocyanine through click chemistry and axial ligation with pyridine
Journal of Electroanalytical Chemistry, 2012Co-Authors: Megan Coates, Tebello NyokongAbstract:Abstract Electrochemical grafting of 4-azidobenzenediazonium salt and click chemistry with ethynylpyridine was used to modify a glassy Carbon Electrode Surface, and iron phthalocyanine was subsequently attached through axial ligation to the Surface pyridine groups. The strong axial bond formed by the interaction between the central metal and the lone pair of the nitrogen in the pyridine group resulted in stable modified Electrodes. The electrocatalytic ability of this sensor was shown using hydrazine as a test analyte, with a linear range from 1.0 × 10−5 to 3.4 × 10−4 M and a limit of detection of 10.0 ± 1.3 μM.
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layer by layer Electrode Surface functionalisation using Carbon nanotubes electrochemical grafting of azide alkyne functions and click chemistry
Electroanalysis, 2012Co-Authors: Megan Coates, Sophie Griveau, Fethi Bedioui, Tebello NyokongAbstract:Ferrocene was covalently bonded to a layer of adsorbed single-walled Carbon nanotubes on a glassy Carbon Electrode Surface using electrochemical grafting and click chemistry. Grafting of the 4-azidobenzenediazonium salt onto the Surface was accomplished by electrochemical reduction. The Surface-bound azide groups, with the use of a copper(I) catalyst, were reacted with ethynylferrocene to form covalent 1,2,3-triazole bonds by click chemistry. This layer by layer construction of the Electrode Surface results in stable Electrodes by combining good electrical conductivity and increased Surface area of the nanotubes with the versatility of the Sharpless click reaction.
Shaojun Dong - One of the best experts on this subject based on the ideXlab platform.
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attachment of gold nanoparticles to glassy Carbon Electrode and its application for the direct electrochemistry and electrocatalytic behavior of hemoglobin
Biosensors and Bioelectronics, 2005Co-Authors: Lei Zhang, Xiue Jiang, Erkang Wang, Shaojun DongAbstract:Abstract Gold nanoparticles have been attached onto glassy Carbon Electrode Surface through sulfhydryl-terminated monolayer and characterized by X-ray photoelectron spectroscopy, atomic force microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The gold nanoparticles-attached glassy Carbon Electrodes have been applied to the immobilization/adsorption of hemoglobin, with a monolayer Surface coverage of about 2.1 × 10 −10 mol cm −2 , and consequently obtained the direct electrochemistry of hemoglobin. Gold nanoparticles, acting as a bridge of electron transfer, can greatly promote the direct electron transfer between hemoglobin and the modified glassy Carbon Electrode without the aid of any electron mediator. In phosphate buffer solution with pH 6.8, hemoglobin shows a pair of well-defined redox waves with formal potential ( E 0 ′) of about −0.085 V (versus Ag/AgCl/saturated KCl). The immobilized hemoglobin maintained its biological activity, showing a Surface controlled Electrode process with the apparent heterogeneous electron transfer rate constant ( k s ) of 1.05 s −1 and charge-transfer coefficient ( a ) of 0.46, and displays the features of a peroxidase in the electrocatalytic reduction of hydrogen peroxide. A potential application of the hemoglobin-immobilized gold nanoparticles modified glassy Carbon Electrode as a biosensor to monitor hydrogen peroxide has been investigated. The steady-state current response increases linearly with hydrogen peroxide concentration from 2.0 × 10 −6 to 2.4 × 10 −4 M. The detection limit (3 σ ) for hydrogen peroxide is 9.1 × 10 −7 M.
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investigation of cetylpyridinium bromide adsorption at a glassy Carbon Electrode Surface by spectroelectrochemistry with a long optical path length thin layer cell
Langmuir, 1991Co-Authors: Shaojun Dong, Yongchun Zhu, Guangjin ChengAbstract:The adsorption of cationic surfactant cetylpyridinium bromide (CPB) on a glassy Carbon (GC) Electrode Surface has been studied by spectroelectrochemistry with a long optical path length thin-layer cell (LOPTLC) for the first time. A fine adsorption isotherm of CPB molecules from an aqueous solution containing 0.10 M KBr has been obtained over the range of (1.00-8.00) x 10(-5) M. From theoretical calculation and experimental data, adsorption of CPB on the GC Electrode Surface shows four distinct orientations and three large orientation transitions. Compared with the ordinary isotherm, the differential isotherm is more characteristic and would be suitable for the study of orientation transitions of organic compounds. With a theoretical treatment of the adsorption isotherm, four orientations of adsorbed CPB on a GC Electrode Surface coincide with the Frumkin-Langmuir type. From adsorption parameters the Frumkin-Langmuir equations, the adsorption free energy and, therefore, the equilibrium constants of orientation transitions of the CPB molecule can be obtained.
Hongyuan Chen - One of the best experts on this subject based on the ideXlab platform.
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direct electron transfer and electrocatalysis of hemoglobin adsorbed on mesoporous Carbon through layer by layer assembly
Biosensors and Bioelectronics, 2007Co-Authors: Jiuju Feng, Hongyuan ChenAbstract:Using chitosan as an effective linker between CMK-3 and glassy Carbon Electrode Surface, {Hb/CMK-3}n multilayer film-modified Electrodes were constructed through layer-by-layer assembly. The morphology of thus-formed {Hb/CMK-3}n film was characterized by scanning electron micrographs, and the interaction of hemoglobin (Hb) with CMK-3 was studied by UV-vis spectroscopy and electrochemical methods. Under optimal conditions, {Hb/CMK-3}6 film showed a couple of stable and well-defined redox peaks at about -377 and -296 mV in pH 7.0 buffers. Furthermore, the {Hb/CMK-3}6 film displayed excellent electrocatalysis to the reduction of both H2O2 and O2. Based on thus-formed film and its direct electron transfer behavior, a novel biosensor was presented for the determination of H2O2 ranging from 1.2 to 57 muM with the detection limit of 0.6microM at S/N=3. CMK-3 provided a desirable matrix for protein immobilization and biosensor preparation.
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an amperometric biosensor based on the coimmobilization of horseradish peroxidase and methylene blue on a Carbon nanotubes modified Electrode
Electroanalysis, 2003Co-Authors: Junjie Zhu, Hongyuan ChenAbstract:A novel hydrogen peroxide biosensor has been constructed based on the characteristics of the Carbon nanotube. The multiwall Carbon nanotube (MWNT) was used as a coimmobilization matrix to incorporate horseradish peroxidase (HRP) and electron transfer mediator methylene blue (MB) onto a glassy Carbon Electrode Surface. Cyclic voltammetry and amperometric measurements were employed to demonstrate the feasibility of methylene blue as an electron carrier between the immobilized peroxidase and the Surface of glassy Carbon Electrode. The amperometric response of this resulting biosensor to H2O2 shows a linear relation in the range from 4 μM to 2 mM. The detection limit was 1 μM when the signal to noise ratio is 3. The presence of dopamine and ascorbic acid hardly affects the sensitive determination of H2O2. This biosensor also possesses very good stability and reproducibility.
Junjie Zhu - One of the best experts on this subject based on the ideXlab platform.
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molecularly imprinted polymers microsphere prepared by precipitation polymerization for hydroquinone recognition
Talanta, 2008Co-Authors: Xianwen Kan, Qun Zhao, Zhong Zhang, Zhilin Wang, Junjie ZhuAbstract:Abstract A one-step precipitation polymerization synthesis was adopted for the preparation of molecularly imprinted polymers (MIPs) by using hydroquinone as a template molecule. The transmission electron microscopy (TEM) exhibited that the polymers were uniform spheres with the diameter of about 700 nm. The results of adsorption experiments showed that the microspherical imprinted polymers possessed fast adsorption dynamics. Compared to the structurally similar compounds, catechol and resorcinol, the MIPs exhibited a high recognizable capacity to hydroquinone. And the electrochemical sensor fabricated by modifying the prepared MIPs microsphere on the glassy Carbon Electrode Surface was used to detect the hydroquinone concentration. The current response was proportional to the concentration of hydroquinone in the range of 2.0 × 10 −6 to 1.0 × 10 −4 mol/L with the detection limit of 1.0 × 10 −6 mol/L.
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an amperometric biosensor based on the coimmobilization of horseradish peroxidase and methylene blue on a Carbon nanotubes modified Electrode
Electroanalysis, 2003Co-Authors: Junjie Zhu, Hongyuan ChenAbstract:A novel hydrogen peroxide biosensor has been constructed based on the characteristics of the Carbon nanotube. The multiwall Carbon nanotube (MWNT) was used as a coimmobilization matrix to incorporate horseradish peroxidase (HRP) and electron transfer mediator methylene blue (MB) onto a glassy Carbon Electrode Surface. Cyclic voltammetry and amperometric measurements were employed to demonstrate the feasibility of methylene blue as an electron carrier between the immobilized peroxidase and the Surface of glassy Carbon Electrode. The amperometric response of this resulting biosensor to H2O2 shows a linear relation in the range from 4 μM to 2 mM. The detection limit was 1 μM when the signal to noise ratio is 3. The presence of dopamine and ascorbic acid hardly affects the sensitive determination of H2O2. This biosensor also possesses very good stability and reproducibility.
Megan Coates - One of the best experts on this subject based on the ideXlab platform.
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Electrode modification using iron metallophthalocyanine through click chemistry and axial ligation with pyridine
Journal of Electroanalytical Chemistry, 2012Co-Authors: Megan Coates, Tebello NyokongAbstract:Abstract Electrochemical grafting of 4-azidobenzenediazonium salt and click chemistry with ethynylpyridine was used to modify a glassy Carbon Electrode Surface, and iron phthalocyanine was subsequently attached through axial ligation to the Surface pyridine groups. The strong axial bond formed by the interaction between the central metal and the lone pair of the nitrogen in the pyridine group resulted in stable modified Electrodes. The electrocatalytic ability of this sensor was shown using hydrazine as a test analyte, with a linear range from 1.0 × 10−5 to 3.4 × 10−4 M and a limit of detection of 10.0 ± 1.3 μM.
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layer by layer Electrode Surface functionalisation using Carbon nanotubes electrochemical grafting of azide alkyne functions and click chemistry
Electroanalysis, 2012Co-Authors: Megan Coates, Sophie Griveau, Fethi Bedioui, Tebello NyokongAbstract:Ferrocene was covalently bonded to a layer of adsorbed single-walled Carbon nanotubes on a glassy Carbon Electrode Surface using electrochemical grafting and click chemistry. Grafting of the 4-azidobenzenediazonium salt onto the Surface was accomplished by electrochemical reduction. The Surface-bound azide groups, with the use of a copper(I) catalyst, were reacted with ethynylferrocene to form covalent 1,2,3-triazole bonds by click chemistry. This layer by layer construction of the Electrode Surface results in stable Electrodes by combining good electrical conductivity and increased Surface area of the nanotubes with the versatility of the Sharpless click reaction.