scholarly journals Mediator-free total cholesterol estimation using a bi-enzyme functionalized nanostructured gold electrode

RSC Advances ◽  
2015 ◽  
Vol 5 (52) ◽  
pp. 41786-41794 ◽  
Author(s):  
Rachna Sharma ◽  
R. K. Sinha ◽  
Ved Varun Agrawal
Keyword(s):  
Total Cholesterol ◽  
Gold Electrode ◽  
Au Electrode ◽  
Nanostructured Gold ◽  
One Step

A one-step electrochemical route for the synthesis, functionalization and deposition of Au nanostructures and for the bi-enzyme functionalization of a Au electrode has been proposed.

Determination of Ascorbic Acid Based on a Platinum Nanoparticles Modified Au Electrode

2011 ◽  
Vol 110-116 ◽  
pp. 1732-1735
Author(s):  
Jia Hong He ◽  
Qiang Xu ◽  
Zhong Rong Song ◽  
Hai Yan Kuang
Keyword(s):  
Electron Microscopy ◽  
Ascorbic Acid ◽  
Modified Electrode ◽  
Platinum Nanoparticles ◽  
Reaction System ◽  
Au Electrode ◽  
Transmission Electron ◽  
Growth Method ◽  
One Step ◽  
The One

A Platinum nanoparticles modified Au electrode has been successfully fabricated by using an in situ growth method. In this method, the Platinum nanoparticles could be grown on the Au electrode surface via the one-step immersion into the mixture of H2PtCl6 (analytical grade, 1g/L), NaBH4 (analytical grade) and polyvinylpyrrolidone K30 (PVP, analytical grade). A certain amount of PVP was added into the reaction system to prevent the coagulation of the Platinum nanoparticles, which obtained by the chemical redox reaction of H2PtCl6 and NaBH4. The structures and morphologies of the Platinum nanoparticles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) . The direct electrochemical behavior of ascorbic acid in 0.3 mol/L NaCl medium at the Platinum nanoparticles modified electrode has been investigated in detail. Compared to a bare Au electrode, a substantial decrease in the overvoltage of the ascorbic acid was observed at the Platinum nanoparticles modified electrode with oxidation starting at ca. 0.20 V vs. SCE (saturated KCl). At an applied potential of 0.18V, this modified electrode produced high and reproducible sensitivity to ascorbic acid and linear responses were obtained over a concentration range from 0.600 to 3.267 μmol/L with a detection limit of 1.9 nmol/L(S/N=3). The fabrication method of this sensor, which has highly sensitive, low working potential, and fast amperometric sensing to ascorbic acid, is simple and without using complex equipment. In addition, the sensor has been successfully used to detect ascorbic acid in real sample, thus is promising for the future development of ascorbic acid sensors.

Determination of Ascorbic Acid Based on a Platinum Nanoparticles Modified Au Electrode

2013 ◽  
Vol 562-565 ◽  
pp. 813-816
Author(s):  
Jia Hong He ◽  
Zhi Qiang Gao ◽  
Zhong Rong Song
Keyword(s):  
Electron Microscopy ◽  
Ascorbic Acid ◽  
Modified Electrode ◽  
Platinum Nanoparticles ◽  
Reaction System ◽  
Au Electrode ◽  
Transmission Electron ◽  
Growth Method ◽  
One Step ◽  
The One

A Platinum nanoparticles modified Au electrode has been successfully fabricated by using an in situ growth method. In this method, the Platinum nanoparticles could be grown on the Au electrode surface via the one-step immersion into the mixture of H2PtCl6 (analytical grade, 1g/L), NaBH4 (analytical grade) and polyvinylpyrrolidone K30 (PVP, analytical grade). A certain amount of PVP was added into the reaction system to prevent the coagulation of the Platinum nanoparticles, which obtained by the chemical redox reaction of H2PtCl6 and NaBH4. The structures and morphologies of the Platinum nanoparticles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) . The direct electrochemical behavior of ascorbic acid in 0.3 mol/L NaCl medium at the Platinum nanoparticles modified electrode has been investigated in detail. Compared to a bare Au electrode, a substantial decrease in the overvoltage of the ascorbic acid was observed at the Platinum nanoparticles modified electrode with oxidation starting at ca. 0.20 V vs. SCE (saturated KCl). At an applied potential of 0.18V, this modified electrode produced high and reproducible sensitivity to ascorbic acid and linear responses were obtained over a concentration range from 0.600 to 3.267 μmol/L with a detection limit of 1.9 nmol/L(S/N=3). The fabrication method of this sensor, which has highly sensitive, low working potential, and fast amperometric sensing to ascorbic acid, is simple and without using complex equipment. In addition, the sensor has been successfully used to detect ascorbic acid in real sample, thus is promising for the future development of ascorbic acid sensors.

X-ray photoelectron spectroscopy studies of aging effects on the surface of Au – a-Si:H – Sb-Cr Schottky diodes

1989 ◽  
Vol 67 (4) ◽  
pp. 365-369 ◽  
Author(s):  
L. Paquin ◽  
M. R. Wertheimer ◽  
E. Sacher ◽  
N. S. McIntyre
Keyword(s):  
Photoelectron Spectroscopy ◽  
Gold Electrode ◽  
Schottky Diodes ◽  
Thick Layer ◽  
Analytical Techniques ◽  
Ambient Air ◽  
Antireflection Coating ◽  
Aging Effects ◽  
Au Electrode ◽  
X Ray

During investigations of Au – a-Si:H – Cr–Sb photovoltaic Schottky diodes, it was observed that photoconversion parameters (1sc, Voc, η) improved markedly with time for samples stored for several weeks in ambient air. This was always accompanied by apparent color changes in the area under the top (Au) electrode, from gold to deep purple, and by evolution of its surface conductivity (σ) from a highly conducting to an insulating state. Profilometry indicated that the colored area rose about 80 nm above the original surface during these changes. These diodes have been examined using depth-profiling surface analytical techniques, namely secondary-ion mass spectroscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy (XPS), but primarily the latter. The XPS studies of the entire layer thickness on the gold electrode were carried out using erosion by Ar+ ion bombardment. The XPS line positions were used to infer electrical properties of silicon and gold constituents.The results show that Si atoms first diffuse through the gold electrode, where they react with atmospheric constituents to form a thick layer composed mainly of SiO2. This layer is responsible for the observed changes in color, a, and 1sc. The latter change, which leads to a maximum rise in η of about 60%, is felt to result from the fact that the SiO2 layer acts as an antireflection coating. Gold from the electrode layer also diffuses outward, mixed intimately with the silicon oxide. Further aging results in a degradation of the electrical continuity of the Au electrode, which is believed to be responsible for the observed slow drop in η.

Electrochemical Properties of a Thiol Monolayers Coated Gold Electrode Modified with Osmium Gel Membrane as Enzyme Sensor

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1193-1198 ◽  
Author(s):  
Tomoki Yabutani ◽  
Nobuyuki Okada ◽  
Kenichi Maruyama ◽  
Junko Motonaka
Keyword(s):  
Gold Electrode ◽  
Glucose Solution ◽  
Electrochemical Analysis ◽  
Current Response ◽  
Current Ratio ◽  
Au Electrode ◽  
Enzyme Sensor ◽  
Self Assembling ◽  
Thiol Monolayers ◽  
Layer Membrane

The electrochemical behavior of an enzyme sensor for glucose using a gold electrode modified with thiol self-assembled membrane and osmium complex gel as an electron transferring mediator has further been investigated by electrochemical analysis. The gold electrode was initially coated with aminomethanethiol self assembling mono layer membrane(thiol-SAM) and then immobilized with glucose oxidase using poly(vinylpyridine-co-allylamine) (PVP-co-AA), gel coordinated with osmium bipyridine complexes (GOD/Os-PVP-co-AA gel). The cleaning condition of the surface of the Au electrode prior to coating thiol SAM was optimized for reduction of interference caused by concomitant compounds. It was found that interfering influence was most efficiently reduced in the case of use of the Au electrode immersed into nitric acid. The current ratio with a thiol coated gold electrode modified with Os-PVP-co-AA gel in glucose solution in the presence to absence of ascorbic acid, acetaminophen, and uric acid ( I D+I / I I ) was 1.006, 1.014, and 1.018, respectively. The peak current response of glucose in the electrode modified with thiol SAM was dropped to 60 – 98% as compared with that without thiol SAM.

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