Electrochemical detection of trace insulin at carbon-nanotube-modified electrodes

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This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Carbon-nanotube (CNT)-modified glassy-carbon electrodes dramatically accelerate the electrooxidation of insulin to offer an attractive amperometric detection of this important hormone. Hydrodynamic voltammograms indicate a substantial lowering of the detection potential, with oxidation starting above +0.5V (versus Ag/AgCl) and leveling off of the response above +0.7V. The flow-injection amperometric response (at pH 7.4) is highly linear (to at least 1000nM), reproducible (RSD=4.8%;n=30), and fast (peak width of 45s). The high sensitivity (48nA/@mM) and moderate detection potential (+0.8V) lead to a low detection limit of 14nM. Such performance characteristics compare favorably with those of previously reported metal-oxide-modified electrodes for insulin, and indicate great promise for in vivo measurements of insulin release and for monitoring this hormone in chromatographic effluents.

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Gas sensing and Electrical Properties of Metal oxide Nanostructures: Nanostructures, Synthesis, sensors, sensing mechanism, LEDs, FETs, Carbon nanotubes, graphene, Supercapacitors

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In the last few years, a little word has attracted enormous attention, and investigation from all over the world. The word is ?nano?. What it presents in terms of science and technology, which are also called nanoscience and nanotechnology, is much more than just a word describing a specific length scale. It has dramatically changed every aspect of the way we think in science and technology and will certainly bring more and more surprises into our daily life as well as into the world of the future. This thesis consists of four parts of which Part-1 gives a brief overview of the synthesis, properties and applications of nanomaterials. Part-2 deals with the synthesis and characterization of different nanostructures of metal oxides and a detailed study of their gas sensing characteristics. Part-3 of the thesis contains results of studies on the electrical properties and hydrogen-sensing characteristics of field effect transistors (FETs) based on nanorods of ZnO and WO2.72. Part-4 of the thesis deals with the supercapacitive behavior of RuO2 and IrO2 functionalized mesoporous carbon and results of studies on the interaction of SWNTs with electron donor and acceptor molecules.

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Metal Oxide Nanoparticles in Organic Solvents: Synthesis, Formation, Assembly and Application

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The synthesis of nanoparticles with control over particle size, shape, and crystalline structure, has long been one of the main objectives in chemistry – and yet these materials are only beginning to be used in nanotechnology. Metal oxides play a significant role in many fields of technology including catalysis, sensing, energy storage and conversion, and electroceramics. It is expected that they could show enhanced or even new properties at the nanoscale. Metal Oxide Nanoparticles in Organic Solvents discusses recent advances in the chemistry involved for the controlled synthesis and assembly of metal oxide nanoparticles, the characterizations required by such nanoobjects, and their size and shape depending properties.

Innovative strategies have to be developed to allow good control from the molecular precursor to the final product at low processing temperatures. In the last few years, a valuable alternative to the well-known aqueous sol-gel processes was developed in the form of nonaqueous solution routes, which can roughly be divided into two methodologies; namely surfactant- and solvent-controlled preparation routes. Metal Oxide Nanoparticles in Organic Solvents reviews and compares surfactant- and solvent-controlled routes, as well as providing an overview of the most important techniques for the characterization of metal oxide nanoparticles, crystallization pathways, the physical properties of metal oxide nanoparticles, their applications in diverse fields of technology, and their assembly into larger nano- and mesostructures.

Researchers and postgraduates in the fields of nanomaterials and sol-gel chemistry will appreciate this book’s informative approach to chemical formation mechanisms in relation to metal oxides.

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A Study of the Conductive Properties of Nanostructured Metal Oxide Films: A Novel Composite MIEC Thin Film Material for SOFCs

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Fuel cells which were first employed in spacecraft, are part of the ongoing pursuit for renewable energy sources, and environmentally compatible electric power generation. Recent enhancements in design and materials might establish fuel cells in a sustainable hydrogen energy economy (SHEE) as viable alternatives to the internal combustion engine. This study investigates the conductive properties of metal-oxide thin films by developing a new deposition technique called dual channel ultrasonic spray pyrolysis (DC-USP). The DC-USP process has proved to be a reliable and cost-effective method to fabricate thin films. We have then created a novel mixed ionic electronic conductor (MIEC) composed of two metal-oxides: lanthanum strontium ferrite and copper-doped bismuth vanadate (LSF.40:BiCuVOx.10). This composite material can contribute to solve the major outstanding problem of the three-phase boundary (TPB) that limits the oxygen reduction reaction to within a microscopic region near the cathode-electrolyte interface in the SOFC device. Results show that at a temperature of 550 C, the average bulk resistivity for LSF.40:BiCuVOx.10 films was 2.08 ohm-cm (a conductivity of 0.48 S/cm).

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Bio-Engineered Batteries?

It seems Angela Belcher’s lab, Biomolecular Materials Group at MIT, has come up with a new microminiature battery, developed from genetically altered viruses, that could change technology as we know it!

The minute size of this battery has incredible application implications for the powering of electronics, electric cars, and the military.

“We can make them in larger diameters,” Belcher said, “but they are all 880 nanometers in length,” which matches the length of the individual virus particles. And, “once we’ve altered the genes of the virus to grow the electrode material, we can easily clone millions of identical copies of the virus to use in assembling our batteries. For the metal oxide we chose cobalt oxide because it has very good specific capacity, which will produce batteries with high energy density.”

More bang for the buck is what this all measures up to. Just to give you an idea of themicroscopicity of this itty bitty battery, a nanometer is one billionth of a meter (500 times smaller than the tip of your pen). And for you engineers, the anode and electrolyte elements for this battery are a done deal. The cathode has given them some difficulty but there are a few working prototypes in the lab, as we speak.

“The nanoscale materials we’ve made supply two to three times the electrical energy for their mass or volume, compared to previous materials,” the team reported.

These futuristic batteries are so tweaky that they could be interwoven into fabric for military applications (the ultimate in warfighting battle armor). “We definitely don’t have full batteries on those [fiber architectures]. We’ve only worked on single electrodes so far, but the idea is to try to make these fiber batteries that could be integrated into textiles and woven into lots of different shapes,” Belcher says, explaining that much of this is still in the works, but that it is conceivably possible, in the very near future, that people’s clothing, cars, aircraft skins, etc. may be interwoven with finely spun power filaments for every application imaginable.

The size and weight of standard batteries powerful enough to propel electric cars has always been an engineering constraint in design.

The positively-charged anode is created by genetically altering the virus so that it draws to itself the materials it needs to become “the positive terminal” of the battery. “Once you do the genetic engineering with the viruses themselves, you pour in the solution and they grow the right combination of these materials on them,” Belcher says. Basically, the microbes collect exotic materials, primarily cobalt oxide and gold. And because these viruses are negatively charged, they can be sandwiched in between oppositely charged polymers to form thin, flexible sheets or spun from liquid crystal like a spiderweb to series or parallel strings of tiny power producing networks.

“What we’re working on is not thinking about a particular device application, but trying to improve the quality of the anode and cathode materials—using biology just to make a higher quality material for energy density,” Belcher says. “We haven’t ruled out cars. That’s a lot of amplification. But right now the thing is trying to make the best material possible, and if we get a really great material, then we have to think about how do you scale it.”

This research was funded by the Army Research Office Institute of Collaborative Biotechnologies, the Institute of Soldier Nanotechnologies and the David and Lucille Packard Foundation.

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