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Selective chemistry for explosives detectionMcHugh, Callum John January 2003 (has links)
No description available.
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Advanced Nanostructured Electrode and Materials Design for Zinc Air BatteriesScott, Jordan 06 November 2014 (has links)
Zinc air batteries have great promise as a new age energy storage device due to their environmental benignity, high energy density in terms of both mass and volume, and low cost Zinc air batteries get their high energy density by using oxygen from the air as the active material. This means that all the mass and volume that are normally required for active material in a battery are replaced by a thin gas diffusion electrode which allows for oxygen from the air to diffuse into the cell. Although this seems ideal, there are many technical challenges associated with the cell being open to the atmosphere. Some of these issues include electrolyte and electrode drying out, poor reaction kinetics involving sluggish reaction, the need for bifunctional catalysts to charge and discharge, and durability of the gas diffusion electrode itself.
The bifuntional catalysts used in these systems are often platinum or other precious metals since these are commonly known to have the highest performance, however the inherent cost of these materials limits the feasibility of zinc air systems. Thus, there is a need to limit or remove the necessity for platinum carbon catalysts. There are many types of non precious metal catalysts which can be used in place of platinum, however their performance is often not as high, and the durability of these catalysts is also weak. Similar limitations on feasibility are invoked by the poor durability of the gas diffusion electrodes. Carbon corrosion occurs at the harsh caustic conditions present at the gas diffusion electrodes, and this corrosion causes catalyst dissolution. Moreover, many issues with zinc electrode fabrication limit durability and usable anode surface area within these systems. There is a need for a stable, porous, high surface area anode with good structural integrity. These issues are addressed in this work by three studies which each focuses on solving some of the issues pertaining to a crucial component of zinc air batteries, those being the gas diffusion electrode, the zinc electrode, and the bifunctional catalyst necessary for oxygen reduction reactions (ORR) and oxygen evolution reactions (OER).
The first study addresses the need for improvements to the zinc anode electrode. A new process is proposed for the production of porous zinc electrodes in which the porosity can be easily controlled. This process involves the mixing of atomized zinc powder with a filler compound such as ammonium chloride. The mixture is then pressed into a pellet and heat treated to a temperature which simultaneously sublimes/decomposes the filler compound, and anneals the zinc structure to improve structural integrity. The resultant porous anode showed significantly charge and discharge potentials over the solid plate anode, while allowing for increased control of porosity over other porous electrodes due to the ability to adjust pore size based on the filler compound particle size. The discharge potentials observed from these porous anodes were 20% greater than zinc plate anodes at 100mA, but up to 200% greater at elevated currents of 200mA. Similarly the charging potentials were 53.8% lower at 100mA, and 55.5% lower at 200mA., suggesting greatly improved performance by the porous anode.
The second study addresses the need for more durable gas diffusion electrodes. In this study, the bifunctional catalyst was bound directly to a stainless steel current collector via polymer binding in an attempt to remove the possibility of carbon corrosion and catalyst dissolution. The new gas diffusion electrode was successful in eliminating carbon corrosion, wherein, the durability of cells which incorporate this type of electrode was significantly increased. The durability of cell was increased to a point where little to no degradation occurred over 1000 cycles of full cell testing, showing great promise for future use and commercial viability.
The final study addresses the need for durable and high performance non precious metal catalysts. The effects of catalyst morphology were studied wherein various morphologies of spinel type cobalt oxide were synthesized and compared. Cobalt oxide nanosheets were successfully synthesized and compared to nanoparticles of comparable size. The cobalt oxide nanosheets showed better charge and discharge potentials as well as durability of the nanoparticles. Impedance analyses showed reduced charge transfer and cell component resistances associated with the nanosheet morphology. Cobalt oxide nanosheets were further compared against platinum carbon. Cobalt oxide nanosheets showed significantly better durability as well as lower charging potentials and higher discharge potentials over 75 cycles. After 75 cycles the platinum carbon had lost 55.7% of its discharge potential wherein cobalt oxide nanosheets lost none of its discharge potential.
Three issues pertaining to three major cell components a zinc air were addressed with promising solutions proposed for each. This work provides a basis for advanced zinc electrode fabrication in which further improvements can be incorporated to address other issues pertaining to zinc electrode use. This work set up a basis for electrode design which focuses on non carbon supported catalysts, eliminating the issue of carbon corrosion and associated catalyst dissolution. Finally, the results from the morphology study elucidate the benefits of controlled morphology for bifunctional catalysts, showing how morphology can be adjusted to improve performance by improving cell and charge transfer resistances.
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Designing high affinity ligands for calmodulinTrevitt, Clare Rosalind January 1999 (has links)
No description available.
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Late Transition Metal Complexes for E-H Bond Activation and Additions to Multiple BondsHesp, Kevin 23 September 2010 (has links)
The study of organometallic chemistry in the context of catalysis can be approached from a stoichiometric perspective, in which PGM complexes are examined in the context of understanding fundamental reactions to provide insight into established catalytic transformations. Alternatively, a catalytic perspective can be adopted, in which an unknown or underdeveloped transformation is identified and PGM catalysis is employed to assist in the further development of this area. In this regard, two general goals of this thesis are: 1) to explore alternative ligation strategies based on P,S-functionalized indene ligands, with a particular focus of studying divergent stoichiometric reactivity between related cationic and zwitterionic PGM complexes; and 2) to identify general PGM catalysts for the cyclohydroamination of alkylaminoalkenes and the hydroamination of internal alkynes with secondary alkylamines.
The preparation and divergent reactivity of a previously unreported class of coordinatively unsaturated cationic and zwitterionic Cp*Ir(P,S) complexes that feature structurally analogous P,S-indene and mono-deprotonated P,S-indenide ancillary ligands, respectively, are discussed. The cationic complex was observed to activate organosilanes via the first well-documented H-Si addition across an M-SR linkage. In contrast, the unusual stoichiometric reactivity of the putative zwitterion with CH3CN or Ph2SiH2 can be viewed as resulting from the dual action of the Lewis acidic Cp*Ir fragment and the Lewis basic 10?-electron indenide unit within this formally charge-separated zwitterion. Building on these initial studies, the synthesis of structurally related (benzyl)Pt(P,S) borato- and carbanion-based zwitterions and cationic complexes featuring the P,S-indene and indenide ligand framework are also presented.
In the context of hydroamination studies, [Ir(COD)Cl]2 was identified as an effective pre-catalyst for the efficient synthesis of pyrrolidine and piperidine heterocycles via the cyclohydroamination of tethered aminoalkenes. Following optimization studies of this catalyst system, a broad substrate scope that included the cyclization of primary and secondary alkyl- or arylamines was established. A kinetic and mechanistic evaluation of this reaction suggested the operative pathway as involving olefin activation in a manner that had not previously been documented for Ir-catalyzed alkene hydroamination. In the pursuit of a general catalyst for the alkyne hydroamination reaction, an effective gold pre-catalyst featuring a P,N-ligand was identified and was used in the addition of a variety of functionalized dialkylamines to internal alkynes. In particular, the first examples of the regioselective addition of dialkylamines to unsymmetrically substituted alkynes are discussed. A preliminary mechanistic survey, consisting of kinetic and stoichiometric experiments, has provided empirical evidence to support a mechanism comprised of turnover-limiting alkyne insertion into a Au?N bond followed by proto-deauration.
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Carbon-based Bifunctional Electrocatalysts for Metal-air Battery ApplicationsLiu, Yulong 06 November 2014 (has links)
The ever-increasing energy consumption and the environmental issues from the excessive rely on fossil fuels have triggered intensive research on the next generation power sources. Metal-air batteries, as one of the most promising technologies emerged, have attracted enormous attention due to its low cost, environmental benignity and high energy density. Among all types of metal-air batteries, Zn-air batteries in particular have tremendous potential for use as alternative energy storage primarily by the low-cost, abundance, low equilibrium potential, environmental benignity, a flat discharge voltage and a longer shell life. However, there are still issues in pertinent to the anode, electrolyte and cathode that remain to be overcome. In particular, the electrocatalyst at the cathode of a metal-air battery which catalyzes the electrochemistry reactions during charge and discharge of the cell plays the most crucial role for the successful commercialization of the metal-air technology.
A series of studies from the carbon nanofibres to spinel cobalt oxide and perovskite lanthanum nickelate was conducted to explore the ORR/OER catalytic properties of those materials which lead to further investigations of the non-precious metal oxide/carbon hybrids as bifunctional catalysts.
Introducing ORR active species such as nitrogen, sulfur, boron and phosphorus into high surface area carbon has been an effective strategy to fabricate high catalytic activity ORR electrocatalyst. Carbon nanofibre is an abundant, low cost and conductive material that has tremendous potential as ORR catalyst, especially via KOH activation and nitrogen-doping post-treatments. These two post-treatment methods serve as simplistic methodologies to enhance the carbon surface area and ORR catalytic activity of the pristine carbon nanofibres, respectively. The activated and nitrogen-doped carbon nanofibres demonstrated 26% of improved half-wave potential and 17% of increased limiting current density as a comparison to the pristine carbon nanofibre via RDE testing in alkaline electrolyte. To realize the catalytic activity of activated and nitrogen-doped carbon nanofibres in a more practical condition, they are further evaluated in Zn-air batteries. Polarization curves retrieved from Zn-air cell testing showed 75% higher voltage obtained by activated and nitrogen-doped carbon nanofibres than pristine carbon nanofibres at 70mAcm-2 current density.
Structured oxides such as spinels and perovskites have been widely reported as ORR and OER catalyst in metal-air batteries. It is widely known that the properties of nanostructures are closely pertinent to their morphologies. The initial performance and durability of cubic Co3O4 synthesized from Feng et al and LaNiO3 from modified sol-gel method are tested in RDE system. After the durability testing, the ORR onset potential and limiting current density of cubic Co3O4 has decreased by 50% and 25%, respectively, whereas the OER limiting current density dropped significantly from ~15mAcm2 to almost zero current density. LaNiO3 with different particle sizes synthesized from modified sol-gel method was prepared and evaluated in RDE system. A particle size related performance can be clearly seen from the RDE results. The ORR limiting current of the lanthanum nickelate with smaller particle size (LNO-1) is higher than that of lanthanum nickelate with larger particle size (LNO-0) by 40% and the OER limiting current of LNO-1 is almost tripled that of LNO-0.
With the previous experience on carbon material and structured oxides, two hybrid bifunctional catalysts were prepared and their performance was evaluated. cCo3O4/ExNG was made by physically mixing of cCo3O4 with ExNG with 1to 1 ratio. The hybrid showed enhanced bifunctional catalytic activities compared to each of its individual performance. Based on the voltammetry results, a significant positive shift (+0.16V) in ORR half-wave potential and tripled limiting current were observed in the case of the hybrid compared to the pure cobalt oxide. By combing cCo3O4 and ExNG, the OER limiting current of the hybrid exceeds that of cCo3O4 by ca. 33% and four-fold that of the ExNG. The kinetic current density at -0.4V for cCo3O4/ExNG is 15.9 mAcm-2 which is roughly 4 times the kinetic current density of the ExNG (3.8 mAcm-2) and over 10 times greater than that of cCo3O4 (1.1 mAcm-2). Electrochemical impedance spectroscopy showed that the charge transfer resistance of the hybrid is ca. one third of cCo3O4 and roughly only one half of ExNG which suggests a more efficient electrocatalysis of the hybrid on the air electrode than the other two.
Mixing structured oxides with carbon material provides a simple method of fabricating bifunctional catalysts, however the interactions between those two materials are quite limited. In-situ synthesis of cCo3O4/MWCNT hybrid by chemically attaching cCo3O4to the acid-functionalized MWCNT is able to provide strong interactions between its components. Through RDE testing, the ORR activity of cCo3O4/MWCNT outperformed its individual component showing the highest onset potential (-0.15V) and current density (-2.91 mAcm-2 at -0.4V) with ~4 electron transfer pathway. Moreover, the MWCNT and cCo3O4 suffered from significant OER degradation after cycling (92% and 94%, respectively) whereas the hybrid material demonstrated an outstanding stability with only 15% of performance decrease, which is also far more superior to the physical mixture (30% higher current density).
Among all the catalyst studied, cCo3O4/MWCNT has the highest performance and durability. The excellent performance of the hybrid warrants further in-depth research of non-precious metal oxide/carbon hybrids and the information presented in this thesis will create afoundation for future investigation towards high performance and durability bifunctional electrocatalysts for metal-air battery applications.
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Perovskite Oxide Combined With Nitrogen-Doped Carbon Nanotubes As Bifunctional Catalyst for Rechargeable Zinc-Air BatteriesIsmayilov, Vugar 28 April 2015 (has links)
Zinc air batteries are among the most promising energy storage devices due to their high energy density, low cost and environmental friendliness. The low mass and cost of zinc air batteries is a result of traditional active materials replacement with a thin gas diffusion layer which allows the battery to use the oxygen directly from the air. Despite the environmental and electronic advantages offered by this system, challenges related to drying the electrolyte and catalyst, determining a high activity bifictional catalyst, and ensuring durability of the gas diffusion layer need to be optimized during the fabrication of rechargeable zinc-air batteries. To date, platinum on carbon (Pt/C) provides the best electrochemical catalytic activity in acidic and alkaline electrolytes. However, the difficult acquisition and high cost of this catalyst mandates investigation into a new composition or synthesis of a bifunctional catalyst. A number of non-precious metal catalyst have been introduced for zinc-air batteries. Nevertheless, their catalytic activities and durability are still too low for commercial rechargeable zinc-air batteries. Thus, it is very important to synthesize a highly active bifunctional catalyst with good durability for long term charge and discharge use. In this study, it is proposed that a manganese-based perovskite oxide nanoparticle combined with nitrogen doped carbon nanotubes willshow promising electrochemical activity with remarkable cycle stability as a bifunctional catalyst for zinc-air batteries.
In the first part of this work, nano-sized LaMnO3 and LaMn0.9Co0.1O3 were prepared to research the effectiveness of Co doping into LaMnO3 and its effect on electrochemical catalytic activities. To prepare LaMnO3 and LaMn0.9Co0.1O3, a hydrothermal reaction method was applied to synthesize nanoparticles which can increase the activity of perovskite type oxides. The result shows that while perovskite oxides replacing 10 wt. % of Mn doped with Co metal did not
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change its crystalline structure, the oxygen evolution reaction (OER) performance was increased by 600%.
In the second part, a core-corona structured bifunctional catalyst (CCBC) was synthesized by combining LaMn0.9Co0.1O3 nanoparticles with nitrogen doped carbon nanotubes (NCNT). NCNT was chosen because of its large surface area and high catalytic activity for ORR. SEM and TEM analysis show that metal oxide nanoparticles were surrounded with nanotubes. Based on the electrochemical performances, ORR and OER activity is attributed to NCNT and the metal oxide core, respectively, complementing the activities of each other. Furthermore, its unique morphology introduces synergetic activity especially for OER. Electrochemical test results show that the onset potential was enhanced from -0.2 V (in LaMnO3 and LaMn0.9Co0.1O3) to -0.09 V (in CCBC) and the half wave potential was improved from -0.38 V to -0.19 V.
In the third part, a single cell zinc-air battery test was performed using CCBC as the bifunctional catalyst for the air electrode. These results were compared with battery performance against a high-performance and expensive Pt/C based air catalyst. The results show that the battery containing catalytic CCBC consumes less energy during charge/discharge. The single cell long-term durability performance was compared, further proving that CCBC provides a more suitable catalyst for zinc-air battery than Pt/C.
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Oxidation State Roulette:Synthesis and Reactivity of Cobalt Complexes Containing SNS LigandsFitchett, Brandon 13 December 2018 (has links)
The use of rare and expensive noble metals in the chemical industry as organometallic catalysts has grown exponentially in the past few decades due to their high activity, selectivity and their ability to catalyze a wide range of reactions. With this growth in use has also come a proportional growth in concern as these toxic metals inevitably leach into the environment and their negative effects on public health and our ecosystems are becoming better understood. First-row transition metal catalysts provide both environmental and economic benefits as alternatives to these noble metals due to their lower toxicity and cheaper costs. The two-electron chemistry that makes the noble metals so attractive however, is more challenging to accomplish with first-row transition metals.
Intelligently designing the ligand scaffold which surrounds the metal can mitigate or even eliminate some of the shortfalls of these first-row metals. Some key features that should be considered when designing a ligand are: 1) a strong chelating ability so the ligand can stay attached to the metal, 2) incorporation of strong donors to favour low-spin complexes, 3) inclusion of hemilabile groups to allow for substrate activation and metal stabilization throughout various oxidation states, 4) redox activity to be able to donate or accept electrons, and 5) inclusion of Lewis base functionalities which are able to assist the substrate activation. Ligands which incorporate these features are known as bifunctional ligands as they can accomplish more than one function in the catalytic cycle. Developing first-row transition metal complexes containing these ligands may enable these species to replicate the reactivity and selectivity generally associated with the precious metals. Being able to replace the noble metals used in industry with these catalysts would have tremendous environmental and economic benefits.
The objective of this thesis is to advance the field of bifunctional catalysis by examining the behaviour of two sterically svelte, tridentate SNS ligands containing hard nitrogen and soft sulphur donors when bonded to cobalt. Previous work with iron provides a template of the ligand behaviour to which cobalt can be compared, allowing us to contrast the effects exerted by the different metals. After an introduction to bifunctional catalysis in Chapter 1, Chapter 2 describes the reactivity of the amido ligand, SMeNHSMe, with precursors ranging from Co(I) to Co(III), all of which yielded the 19e- pseudooctahedral cobalt(II) bis-amido complex, Co(SMeN-SMe)2 characterized by 1H NMR spectroscopy, single-crystal X-ray crystallography and cyclic voltammetry. Although this complex has a similar structure as the Fe analogue, the cobalt bis-amido complex did not exhibit the same hemilabile behaviour that allowed for simple ligand substitution of one of the thioether groups. Instead it reacted reversibly with 2,2’-bipyridine while 1,2-bis(dimethylphosphino)ethane (DMPE) and 2,6-dimethylphenyl isocyanide both triggered additional redox chemistry accompanied by the loss of protonated SMeNHSMe. In contrast, protonation gave the cobalt(II) amido-amine cation, [Co(SMeNSMe)(SMeNHSMe)](NTf2), which allowed for substitution of the protonated ligand by acetonitrile, triphenylphosphine and 2,2’-bipyridine based on 1H NMR evidence. The ability of Co(SMeNSMe)2 to act as a precatalyst for ammonia-borane dehydrogenation was also probed, revealing that it was unstable under these conditions. Addition of one equivalent of DMPE per cobalt, however, resulted in better activity with a preference for linear aminoborane oligomers using ammonia-borane and, surprisingly, to a change in selectivity to prefer cyclic products when moving to methylamine-borane.
Chapter 3 delves into the chemistry of the thiolate ligand, SMeNHS, which formed a new 18e- cobalt(III) pseudooctahedral complex, Co(S-NC-)(SMe)(DEPE), from oxidative addition of the Caryl-SMe bond. Scaling up this reaction resulted instead in formation of an imine-coupled [Co(N2S2)]- anion which was characterized by 1H NMR/EPR spectroscopy, single-crystal X-ray diffraction, cyclic voltammetry and DFT studies. The latter revealed an interesting electronic structure with two electrons delocalized in the ligand, demonstrating the non-innocent nature of the N2S2 ligand. While the analogous iron complex proved to be an effective pre-catalyst for the hydroboration of aldehydes with selectivity against ketones, this behaviour was not observed with [Co(N2S2)]- which gave a slower rate and less selectivity.
The knowledge acquired from this thesis work has advanced the field of bifunctional catalysis by extending the application of these two SNS ligands from iron to cobalt, revealing unpredictable differences in reactivity between the metals. By comparing the behaviour of these ligands with iron and cobalt, we gain a better understanding of the chemistry that is accessible by these ligands and the applications for which they may be used. This increased knowledge contributes to our long-term goal of replacing expensive and toxic noble metals with more benign first-row transition metals, improving the sustainability of the chemical industry.
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Covalent Immune Proximity-Induction Strategy Using SuFEx-Engineered Bifunctional Viral PeptidesMcCann, Harrison January 2023 (has links)
Harnessing the immune system is a powerful tool in chemical biology and is the focus of cancer immunotherapy. Often, this is accomplished through monoclonal antibodies which recognize and recruit immune effector cells to an over-expressed cancer antigen presented at the cancer cell surface. More recently, there has been great interest in developing small molecule therapeutics which replicate this, but with lower developmental costs, greater modularity, and improved tumor penetration. One such class of therapeutics are bifunctional molecules known as antibody recruiting molecules, which form molecular bridges between two targets, i.e., a cancer receptor and antibody. Limitations in ternary complex formation between bifunctional molecules and their two binding targets has presented the need for increasing residence time at key junctions. Demonstrated here is the development of a covalent proximity-induction approach which leverages molecular recognition to drive an electrophilic warhead near a nucleophile within a target antibody binding site. Subsequent irreversible labeling reprograms these antibodies with tumor binding handles in situ for enhanced tumor opsonization and immune clearance mechanisms. This was accomplished by equipping a viral peptide epitope with a sulfur (VI) fluoride exchange electrophile to irreversibly label anti-herpes simplex virus (HSV) antibodies. Using the aryl sulfonyl fluoride warhead, we demonstrate fast and selective labeling for both model monoclonal antibodies, as well as natural polyclonal anti-HSV antibodies. Covalently reprogrammed antibodies elicited superior potency at both lower concentrations and with cell lines having lower antigen presentation. This proof of concept has broad applicability in developing covalent bifunctional molecules for bridging one or more protein:protein interactions. / Dissertation / Master of Science (MSc)
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Novel Bifunctional Ligands For Neuropathic Pain: Design and Synthesis of Overlapping Pharmacophores of Opioid and Melanocortin LigandsKulkarni, Vinod V. January 2012 (has links)
Biologically many disease states lead to changes in expressed proteins. Therefore, "system changes" that occur must be considered in any treatment for the disease. This new approach to drug design and discovery would be particularly applicable to the diseases that involve adaptive changes in the central nervous system, such as neuropathic pain. There is growing evidence that drugs behave differently in pathological states than in normal states, thus preventing their effectiveness in pathological disease states. Therefore, a new paradigm for drug design is needed. In recent years, the melanocortin-4 receptor (MC4R) found in the spinal cord and CNS has received growing attention as a therapeutic target. MC4R based agonist ligands produce anti-opioid effects, and researchers have shown that an antagonist of the MC4R can produce pronounced anti-allodynic effect. Opioid receptors have been the central and most efficacious targets sought after for relieving neuropathic pain. In our new approach, single peptide molecules are designed to interact with opioid receptors as an agonist, and as an antagonist at the MC4 receptor. For the treatment of pain, a series of linear and cyclic peptides based on the overlapping pharmacophores of endogenous melanocyte stimulating hormone and opioid ligands are designed through computational aided molecular modeling and synthesized. Throughout the studies the opioid pharmacophore is maintained towards the N-terminal while melanocortin pharmacophore is maintained towards the C-terminal. Cyclization of peptides has been the central synthetic feature in designing the bifunctional ligands. The use of microwave has been shown to be very efficient in cyclizing the peptides. Solvent, reagent, power and temperature conditions are established for the microwave application in aiding the macromolecules for cyclizing their side chain termini.
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Desenvolvimento de uma superfície bifuncional Pt/Au modificada com glicose oxidase para determinação de glicose em amostras alimentícias / Development of a bifunctional surface Pt/Au modified with glucose oxidase for glucose determination in food samplesDadamos, Tony Rogério de Lima 19 July 2013 (has links)
A glicose é um açúcar redutor importante na dieta humana, sendo abundante em diversos alimentos, como sucos de frutas, mel, iogurtes e refrigerantes e pode ser facilmente ingerido e metabolizado. Ela fornece a energia para o corpo humano, entretanto, diversos desequilíbrios metabólicos estão associados com variações no teor de glicose no sangue, saliva ou urina. Sendo assim é preciso desenvolver métodos de baixo custo, simples e rápidos que permitam o monitoramento deste metabólito. Portanto, no presente trabalho foi desenvolvido e caracterizado um eletrodo composto por uma superfície bifuncional de Pt/Au, onde a superfície de Au foi modificada com uma monocamada auto-organizada de cistamina na qual foi ancorada a enzima glicose oxidase e a superfície da Pt com ferroceno, para determinação de glicose em amostras alimentícias. O eletrodo foi construído utilizando-se um eletrodo de platina, sobre o qual foram eletrodepositado nanoestruturas de ouro, através de voltametria linear em uma solução contendo o ânion tetracloroáurico. As nanoestruturas de ouro foram modificadas com o alcanotiol cistamina, formando uma camada auto-organizada, para servir de plataforma para ancoragem da glicose oxidase. O peróxido de hidrogênio, que é um dos produtos da reação enzimática foi determinado na platina modificada com ferroceno. Sendo assim, as nanoestruturas de ouro serviriam de sítios específicos para as enzimas, e a platina modificada com ferroceno servirá para quantificar o produto da reação enzimática. Para a detecção da glicose foram construídos três eletrodos, o eletrodo embutido (EE) para detecção de glicose em refrigerantes, o eletrodo por evaporação de platina (EEP) para detecção de glicose em amostras de iogurte e o ultramicroeletrodo (UME) para futuras aplicações de detecção de glicose por métodos não invasivos. Encontrou-se um limite de detecção de 2,4 µmol L-1 para o eletrodo EE, de 2,2 µmol L-1 para o eletrodo EEP e 0,03 µmol L-1 para o UME. Foram realizados diversos tratamentos estatísticos como erro relativo, desvio padrão e incertezas para verificar a resposta do eletrodo. Por fim, os eletrodos desenvolvidos foram aplicados na detecção de glicose em amostras de refrigerantes, chás e iogurtes, e obteve-se uma resposta satisfatória para a detecção do analito nestas amostras. / Glucose is a reducing sugar very important in the human diet and is abundant in many foods, such as fruit juices, honey, yogurt and soft drinks and can be easily ingested and metabolized. It provides the energy for the human body perform its healthy functioning. However, many metabolic imbalances associated with variations in the level of glucose in the blood, urine or saliva. Therefore it is necessary to develop methods cheap, simple and quick to allow the monitoring of this metabolite. Therefore, in the present work was developed and characterized an electrode composed of a bifunctional surface Pt/Au, where Au surface was modified with a selforganized monolayer of cystamine which was anchored in the enzyme glucose oxidase and the surface of Pt with ferrocene for the determination of glucose in food samples. The electrode was constructed using a platinum electrode, which was electrodeposited gold nanostructures, using the technique of linear voltammetry in a solution containing the anion tetrachloroauric. The gold nanostructures were modified with cystamine alkanethiol forming a self-organized layer to serve as a platform for anchoring the glucose oxidase. Hydrogen peroxide, which is a product of the enzyme reaction, was determined in the platinum modified with ferrocene. Therefore, the gold nanostructures serve as sites for specific enzymes, and platinum modified with ferrocene serve to quantify the product of the enzymatic reaction. For detection of glucose were built three electrodes, the electrode embedded (EE) for detecting glucose in soft drinks, the electrode by evaporating platinum (EEP) for detection of glucose in samples of yogurt and ultramicroelectrode (UME) for future sensing applications glucose through non-evasive. We found a detection limit of 2.4 µmol L-1 to the electrode EE, 2.2 µmol L-1 to the electrode EEP and 0.03 µmol L-1 for UME. Various statistical treatments were performed as relative error, standard deviation and uncertainties to check the response of the electrode. Finally, the electrodes developed were applied to the detection of glucose in samples of soft drinks, teas and yogurts, which gave a satisfactory response to the detection of the analyte in food samples.
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