Improvement of carbon materials performance by nitrogen functional groups in electrochemical capacitors in organic electrolyte at severe conditions

N-doped activated carbon fibers have been synthesized by using chemically polymerized aniline as source of nitrogen. Commercial activated carbon fibers (A20) were chemically modified with a thin film of polyaniline (PANI) inside the microporosity of the carbon fibers. The modified activated carbon fibers were carbonized at 600 and 800 °C, respectively. In this way, activated carbon fibers modified with surface nitrogen species were prepared in order to analyze their influence in the performance of electrochemical capacitors in organic electrolyte. Symmetric capacitors were made of activated carbon fibers and N-doped activated carbon fibers and tested in a two-electrode cell configuration, using triethylmethylammonium tetrafluoroborate/propylene carbonate (TEMA-BF4/PC) as electrolyte. The effect of nitrogen species in the degradation or stabilization of the capacitor has been analyzed through floating durability tests using a high voltage charging (3.2 V). The results show higher stabilizing effect in carbonized samples (N-ACF) than in non-carbonized samples and pristine activated carbon fibers, which is attributed to the presence of aromatic nitrogen group, especially positively charged N-functional groups.

Caracterização reológica de pastas de cimento portland de alta resistência contendo diferentes tipos de polímeros superabsorventes pela técnica de reometria rotacional

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2016.

Preparation of an Immunosorbent and its use in the Solid Phase Extraction of Benzodiazepines

The use of capillary electrophoresis (CE) has been restricted to applications having high sample concentrations because of its low sensitivity caused by small injection volumes and, when ultraviolet (UV) detection is used, the short optical path length. Sensitivity in CE can be improved by using more sensitive detection systems, or by preconcentration techniques which are based on chromatographic and/or electrophoretic principles. One of the promising strategies to improve sensitivity is solid phase extraction (SPE). Solid Phase Extraction utilizes high sample volumes and a variety of complex matrixes to facilitate trace detection. To increase the specificity of the SPE a selective solid phase must be chosen. Immunosorbents, which are a combination of an antibody and a solid support, have proven to be an excellent option because of high selectivity of the antibody. This thesis is an exploratory study of the application of immunosorbent-SPE combined with CE for trace concentration of benzodiazepines. This research describes the immobilization and performance evaluation of an immunosorbent prepared by immobilizing a benzodiazepine-specific antibody on aminopropyl silica. The binding capacity of the immunosorbent, measured as µg of benzodiazepine/ gram of immunosorbent, was 39 ± 10. The long term stability of the prepared immunosorbent has been improved by capping the remaining aminopropyl groups by reaction with acetic anhydride. The capped immunosorbent retained its binding capacity after several uses.

Microspheres for Liver Radiomicrospheres Therapy and Planning

Liver cancer accounts for nearly 10% of all cancers in the US. Intrahepatic Arterial Radiomicrosphere Therapy (RMT), also known as Selective Internal Radiation Treatment (SIRT), is one of the evolving treatment modalities. Successful patient clinical outcomes require suitable treatment planning followed by delivery of the microspheres for therapy. The production and in vitro evaluation of various polymers (PGCD, CHS and CHSg) microspheres for a RMT and RMT planning are described. Microparticles with a 30±10 µm size distribution were prepared by emulsion method. The in vitro half-life of the particles was determined in PBS buffer and porcine plasma and their potential application (treatment or treatment planning) established. Further, the fast degrading microspheres (≤ 48 hours in vitro half-life) were labeled with 68Ga and/or 99mTc as they are suitable for the imaging component of treatment planning, which is the primary emphasis of this dissertation. Labeling kinetics demonstrated that 68Ga-PGCD, 68Ga-CHSg and 68Ga-NOTA-CHSg can be labeled with more than 95% yield in 15 minutes; 99mTc-PGCD and 99mTc-CHSg can also be labeled with high yield within 15-30 minutes. In vitro stability after four hours was more than 90% in saline and PBS buffer for all of them. Experiments in reconstituted hemoglobin lysate were also performed. Two successful imaging (RMT planning) agents were found: 99mTc-CHSg and 68Ga-NOTA-CHSg. For the 99mTc-PGCD a successful perfusion image was obtained after 10 minutes, however the in vivo degradation was very fast (half-life), releasing the 99mTc from the lungs. Slow degrading CHS microparticles (> 21 days half-life) were modified with p-SCN-b-DOTA and labeled with 90Y for production of 90Y-DOTA-CHS. Radiochemical purity was evaluated in vitro and in vivo showing more than 90% stability after 72 and 24 hours respectively. All agents were compared to their respective gold standards (99mTc-MAA for 68Ga-NOTA-CHSg and 99mTc-CHSg; 90Y-SirTEX for 90Y-DOTA-CHS) showing superior in vivo stability. RMT and RMT planning agents (Therapy, PET and SPECT imaging) were designed and successfully evaluated in vitro and in vivo.

Fabrication of heterogeneous biocatalyst tethering artificial prosthetic groups to obtain omega-3-fatty acids by selective hydrolysis of fish oils

The active site of lipase from Bacillus thermocathenolatus was selectively modified with allyl and naphthyl chains at different positions. Lipase immobilization and selective tethering of a naphthyl side chain to its position 320 improve both the hydrolysis rate of fish oils and the selectivity towards the eicosapentaenoic acid acyl chains. © The Royal Society of Chemistry 2016.

Desenvolvimento de métodos electroquímicos de quantificação de fármacos em amostras de água contaminadas

Este trabalho teve como objectivo, o desenvolvimento de um método electroquímico, para quantificação do fármaco carbamazepina (CBZ) em águas contaminadas. Neste trabalho foram utilizados quatro métodos voltamétricos: a voltametria cíclica, a voltametria de varrimento linear, a voltametria de onda quadrada e a voltametria de impulso diferencial. Os eléctrodos de trabalho utilizados foram, o eléctrodo de mercúrio de gota suspensa, o eléctrodo de carbono vítreo clássico e um eléctrodo de carbono vítreo modificado com um filme de nanotubos de carbono de paredes múltiplas (MWCNTs). O eléctrodo de mercúrio de gota suspensa permitiu o estudo da redução da CBZ numa região de potencial mais catódico, e os eléctrodos de carbono vítreo, com e sem modificação, permitiram o estudo da oxidação da CBZ numa região de potencial mais anódico. Nas condições experimentais estudadas, o eléctrodo de mercúrio de gota suspensa revelou ser um sensor voltamétrico pouco eficaz na determinação quantitativa da carbamazepina, em amostras com uma matriz complexa. Entre os eléctrodos de carbono vítreo, o eléctrodo de carbono vítreo modificado com os MWCNTs revelou ser o sensor voltamétrico mais eficaz e sensível, na detecção e determinação da carbamazepina. Modificado com um filme de nanotubos de carbono de paredes múltiplas, que previamente foram dispersos em dihexadecilhidrogenofosfato (DHP) e água, este novo eléctrodo permitiu obter uma resposta electroquímica da CBZ, consideravelmente superior ao eléctrodo não modificado. Utilizando a voltametria de varrimento linear e as condições experimentais consideradas óptimas, o eléctrodo nanoestruturado permitiu obter uma relação linear entre o sinal medido e a concentração da CBZ no intervalo 0.13- 1.60 M (30.7- 378 g -1), com os limites de detecção e quantificação mais baixos, até à data reportados com métodos electroquímicos (0.04 e 0.14M, respectivamente). O eléctrodo modificado foi aplicado na quantificação da CBZ, em formulações farmacêuticas, em águas naturais tratadas e em amostras de águas residuais, ambas dopadas, obtendo-se taxas de recuperação consideravelmente elevadas (100.6%, 98.0%,95.8%, respectivamente). Os resultados obtidos, na análise da CBZ em amostras ambientais, com o eléctrodo modificado, foram comparados com resultados obtidos por HPLC-UV e LC­ ESI-MS/MS, validando o método electroquímico desenvolvido neste trabalho. ABSTRACT: The aim of this work was to develop a new electrochemical method for the quantification of carbamazepine (CBZ) in contaminated waters. ln this study, four voltammetric methods were used: cyclic voltammetry, linear sweep voltammetry, square wave voltammetry and differential pulse voltammetry. the working electrodes used were the hanging mercury drop electrode (HMDE), the classical glassy carbon electrode (GCE), and a glassy carbon electrode modified with a film of multi-walled carbon nanotubes (MWCNls). Using HMDE, the reduction of CBZ was studied in the cathodic potential region. the CGE sensors, with or without modification, allowed the study of CBZ oxidation in the anodic potential region. ln the tested conditions, the results obtained for the quantification of CBZ using the HMDE sensor were not very satisfactory, especially when more complex samples were analysed. When the MWCNls-dihexadecyl hydrogen phosphate (DHP) film­ coated GCE was used for the voltammetric determination of CBZ, the results obtained showed that this modified electrode exhibits excellent enhancement effects on the electrochemical oxidation of CBZ. the oxidation peak current of CBZ at this film­ modified electrode increased significantly, when compared with that at a bare glassy carbon electrode. The enhanced electrooxidation and voltammetry of CBZ at the surface of MWCNTs-DHP film coated GCE in phosphate buffer solution (pH 6.71) was attributed to the unique properties of MWCNTs such as large specific surface area and strong adsorptive properties providing more reaction sites. The proposed method was applied to the quantification of CBZ in pharmaceutical formulations, drinking water and wastewater samples with good recoveries and low limits of detection and quantification (0.04 and 0.14 M, respectively), and was positively compared with chromatographic techniques usually used in the quantification of pharmaceutical compounds in environmental samples. HPLC-UV and LC-ESI-MS/MS were also used in the quantification of CBZ in pharmaceutical formulations and wastewater samples to prove the importance and accuracy of his voltammetric method.

Novel dual D3R/GSK-3β modulators: an innovative multitarget strategy for bipolar disorder

Among the psychiatric diseases, bipolar disorder (BD) is the sixth leading cause of disability with a prevalence up to 4 % worldwide. BD is a complex neuropsychiatric condition which alternates episodes of mania with symptoms of depression. Although the neurobiological pathways are not completely clarified, the dopamine (DA) hypothesis, recognized as the leading theory explaining the pathophysiology of the malady, states that the dramatically compromised homeostatic regulation of dopaminergic circuits leads to alternated changes in DA neurotransmission. Modulation of D2 and D3 receptors (D2/3R) through partial agonists represents the first-line therapeutic strategy for psychiatric diseases. Moreover, a deregulation of the enzyme glycogen synthase kinase-3β (GSK-3β) has been reported as peculiar feature of BD. In this scenario, the concomitant modulation of D3R and GSK-3β, by employing multitarget compounds, could offer promises to achieve an effective cure of this illness. In the light of these findings, we rationally envisaged the pharmacophoric model at the basis of the design of several D3R partial agonists, suitable to be exploited for the dual D3R/GSK-3β ligand design. Thus, synthetic efforts were addressed to develop a first set of hybrid molecules able to concurrently modulate the selected targets. For a chemical structure point of view, we employed different spacers to combine a substituted aryl-piperazine moiety, reported in previously discovered D3R modulators, with a pyrazole-based fragment, already identified in GSK-3β inhibitors. A fluorescent and a cellular functional assays were carried out to assess the activity of all synthetized compounds against GSK-3β and on D3R, respectively. Most of the derivatives proved to effectively modulate both GSK-3β and D3R with potencies in the low-µM and low-nM range, respectively. The consistent biological data allowed us to identify some lead candidates worth to be further modified with the aim to optimize their biological profile and to perform a structure-activity relationship (SAR) study.

Novel catalytic systems and methidologies for organocatalysis and photocatalysis

The thesis is divided into two main parts. In the first one organocatalysis is briefly introduced. Then, new enantiopure trityl pyrrolidines modified with an ionic tag are described. All the catalysts are tested in the benchmark Michael addition reaction to prove their activity and stereoselectivity. In the second part, photocatalysis is first introduced. Then, four different research projects are described. At first, the construction of a hybrid metal-organo-photoredox catalyst is described. The hybrid photocatalysts obtained were employed in the benchmark photoredox alkylation of aldehydes. Then, the use of visible light and a photocatalytic system for the cyclization of iodoaryl vinyl derivatives to tetrahydroquinoline structures is described. In addition, the reaction can also be performed using flow-chemistry. Finally, a mechanistic proposal based on some mechanistic studies is described. Third, a new photoredox catalyzed transformation for the synthesis of 2,3-dihydrofurans is reported. Depending on the involved starting materials, different pathways have arisen. A mechanistic proposal based on reported literatures and experimental data is described. At last, a new photoredox catalyzed transformation for the synthesis of 2-aminofurans is described. Electrophilic radical addition on allenamides and subsequential intramolecular cyclization are exploited. The reaction proceeds under very mild conditions and in 2-aminofurans are obtained in good to high yield. It represents one of the few applications of allenamides in photoredox catalysis. A mechanistic proposal is described. Finally, preliminary investigations on the applicability of the developed transformation under flow chemistry conditions.

Development of a colorimetric indicator label for food oxidation based on hexanal detection

In this work, a colorimetric indicator for food oxidation based on the detection of hexanal in gas-phase, has been developed. In fact, in recent years, the food packaging industry has evolved towards new generation of packaging, like active and intelligent. According to literature (Pangloli P. et al. 2002), hexanal is the main product of a fatty acid oxidation: the linoleic acid. So, it was chosen to analyse two kinds of potato chips, fried in two different oils with high concentration of linoleic acid: olive oil and sunflower oil. Five different formulas were prepared and their colour change when exposed to hexanal in gas phase was evaluated. The formulas evaluations were first conducted on filter paper labels. The next step was to select the thickener to add to the formula, in order to coat a polypropylene film, more appropriate than the filter paper for a production at industrial scale. Three kinds of thickeners were tested: a cellulose derivative, an ethylene vinyl-alcohol and a polyvinyl alcohol. To obtain the final labels with the autoadhesive layer, the polypropylene film with the selected formula and thickener was coat with a water based adhesive. For both filter paper and polypropylene labels, with and without autoadhesive layer, the detection limit and the detection time were measured. For the selected formula on filter paper labels, the stability was evaluated, when conserved on the dark or on the light, in order to determine the storage time. Both potato chips samples, stocked at the same conditions, were analysed using an optimised Headspace-Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) method, in order to determine the concentration of volatilized hexanal. With the aim to establish if the hexanal can be considered as an indicator of the end of potato chips shelf life, sensory evaluation was conducted each day of HS-SPME-GC-MS analysis.

Polyaniline-based materials and nanocomposites: from energy storage to sensing applications

The research work described in this thesis concerns materials for both energy storage and sensoristics applications. Firstly, the synthesis and characterization of magnetite (Fe3O4) functionalyzed with [3-(2-propynylcarbamate)propyl]triethoxysilane (PPTEOS) capable to reduce the gold precursor chloroauric acid (HAuCl4) without the need of additional reducing or stabilising agents is described. These nanoparticles were tested to improve performances of symmetric capacitors based on polyaniline and graphite foil. Energy storage applications were investigated also during six months stay at EPFL University of Lausanne where an investigation about different tailored catalysts for Oxygen Evolution Reaction in a particular Redox Flow Battery was carried out. For what concerns sensing applications, new materials based on cellulose modified with polyaniline and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAAMPSA) were synthesized, characterized and applied to monitor pressure, humidity, heart rate and lastly, bread fermentation in collaboration with the University of Fribourg and Zurich. The characterizations of all the materials investigated compriseed numerous techniques such as infrared attenuated total reflectance spectroscopy (IR-ATR), thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM), alongside linear and cyclic voltammetry (LSV and CV), electrochemical impedance spectroscopy (EIS) and chronoamperometric analyses.

Valorization of bio-alcohols into added value chemicals

The present research work focused on the valorisation and upgrading of bio-ethanol over heterogeneous catalysts in a lab-scale continuous gas-flow system. In the Unibo laboratories, catalytic tests have been carried out in the temperature range 300-600°C by feeding an ethanol/He mixture in the reactor. After choosing the reaction conditions, ion-exchanged hydroxyapatite with transition metals (i.e., Fe, Cu) and alkaline earth metal (i.e., Sr) have been synthesized and tested. The Sr-HAP catalyst led to the formation of a complex reaction mixture the composition of which need further optimization in order to fill the requisite to be used as fuel-blend. Then, some zirconium-oxide based catalysts have been prepared through two different methods, precipitation and hydrothermal, by varying some synthetic parameters (i.e., pH, the nature of the base) and by adding a transition metal as dopant agent (i.e., Ti and Y). The presence of a dopant into the zirconia structure favoured the stabilization of the tetragonal or cubic phase against the monoclinic one. Interestingly, 5%mol Ti-doped zirconia exhibited a different catalytic behaviour yielding diethyl ether as major product at 300°C, while all the others samples produced mainly ethylene. Then, the effect of acid-base properties of sepiolite, using alkali metals (i.e., Na, K, Cs) with different metal loading (i.e., 2, 4, 5, 7, 14 wt%) as promoters, and of the redox properties of sepiolite-supported CuO or NiO, on the catalytic conversion of ethanol into n-butanol has been investigated. Thermal treated sepiolite samples mainly acted as acid catalyst, yielding preferentially the dehydration products of ethanol (ethylene and diethyl ether). Best results in terms of activity (ethanol conversion, 59%) and n-butanol selectivity (30%) where obtained at 400ºC and a contact time, W/F, of 2 g/mL·s over the catalyst consisting of sepiolite calcined at 500ºC modified with 7 wt% of cesium.

Design of luminescent metal complexes for polymer science

The program of my PhD studies has been dealing with the investigation of the research outcomes that may result from the use of luminescent Iridium(III) cyclometalated complexes in the field of polymer science. In particular, my activity has been focused on exploring two main applicative contexts, i.e. Ir(III) complexes for preparing polymers and in combination with polymers. In the first part, a new set of luminescent Ir(III) complexes was exploited as photocatalysts for light-assisted atom transfer radical polymerization of methyl methacrylate. The decoration of both cyclometalated and ancillary ligands with sp3 hybridized nitrogen substituents together with the use of specific counterions, imparted suitable photophysical and redox properties for an efficient photocatalyzed process. The second part has been focused on the employment of Ir(III) tetrazole complexes as phosphorescent dyes in polymeric materials. Colourless luminescent solar concentrators were prepared blending two Ir(III) cyclometalates with acrylate polymers. Their performances were investigated, leading to promising outcomes comparable, or superior, to those obtained from colourless LSCs based on organic fluorophores. As a complementary approach, Ir(III) complexes were covalently linked to polymers in the side chain, to obtain a new class of metallopolymers. To this extent, a bifunctional tetrazolate molecule, equipped with a coordination site and a polymerizable unit, was designed. The photophysical properties of the resultant luminescent polymeric films were discussed. In the end, an additional project involving both polymers and metal compounds was carried out during my experience as a visiting PhD student at Humboldt – University of Berlin. Polystyrene and polyethylene glycol -based ion-exchange resins were functionalized with peptides through a ligation pathway, for the selective chelation of Copper(II) in aqueous solutions. The coordinating capability of the materials towards Cu2+ ions was tested by ICP-MS analysis. The resins strategically modified with ion-selective peptides, may be exploited in the preparation of water-processing devices.

Inkjet-printed poly(N-isopropylacrylamide)/graphene electrodes for selective electroanalytical sensing

The main research topic of the present master thesis consisted in the modification and electrochemical testing of inkjet printed graphene electrodes with a thin polymeric hydrogel layer made of cross-linked poly(N-isopropylacrylamide) (PNIPAAM) acting as a functional layer to fabricate selective sensors. The first experimental activities dealt with the synthesis of the polymeric hydrogel and the modification of the active surface of graphene sensors through photopolymerization. Simultaneous inkjet printing and photopolymerization of the hydrogel precursor inks onto graphene demonstrated to be the most effective and reproducible technique for the modification of the electrode with PNIPAAM. The electrochemical performance of the modified electrodes was tested through cyclic voltammetry. Voltammograms with standard redox couples with either positive, neutral or negative charges, suggested an electrostatic filtering effect by the hydrogel blocking negatively charged redox species in near neutral pH electrolyte solutions from reaching the electrode surface. PNIPAAM is a known thermo-responsive polymer, but the variation of temperature did not influence the filtering properties of the hydrogels for the redox couples studied. However, a variation of the filter capacity of the material was observed at pH 2 in which the PNIPAAM hydrogel, most likely in protonated form, became impermeable to positively charged redox species and permeable to negatively charged species. Finally, the filtering capacity of the electrodes modified with PNIPAAM was evaluated for the electrochemical determination of analytes in presence of negatively charge potential interferents, such as antioxidants like ascorbic acid. The outcome of the final experiments suggested the possibility to use the inkjet-printed PNIPAAM thin layer for electroanalytical applications as an electrostatic filter against interferents of opposite charges, typically present in complex matrices, such as food and beverages.

Versatile microanalytical system with porous polypropylene capillary membrane for calibration gas generation and trace gaseous pollutants sampling applied to the analysis of formaldehyde, formic acid, acetic acid and ammonia in outdoor air

The analytical determination of atmospheric pollutants still presents challenges due to the low-level concentrations (frequently in the mu g m(-3) range) and their variations with sampling site and time In this work a capillary membrane diffusion scrubber (CMDS) was scaled down to match with capillary electrophoresis (CE) a quick separation technique that requires nothing more than some nanoliters of sample and when combined with capacitively coupled contactless conductometric detection (C(4)D) is particularly favorable for ionic species that do not absorb in the UV-vis region like the target analytes formaldehyde formic acid acetic acid and ammonium The CMDS was coaxially assembled inside a PTFE tube and fed with acceptor phase (deionized water for species with a high Henry s constant such as formaldehyde and carboxylic acids or acidic solution for ammonia sampling with equilibrium displacement to the non-volatile ammonium ion) at a low flow rate (8 3 nLs(-1)) while the sample was aspirated through the annular gap of the concentric tubes at 25 mLs(-1) A second unit in all similar to the CMDS was operated as a capillary membrane diffusion emitter (CMDE) generating a gas flow with know concentrations of ammonia for the evaluation of the CMDS The fluids of the system were driven with inexpensive aquarium air pumps and the collected samples were stored in vials cooled by a Peltier element Complete protocols were developed for the analysis in air of NH(3) CH(3)COOH HCOOH and with a derivatization setup CH(2)O by associating the CMDS collection with the determination by CE-C(4)D The ammonia concentrations obtained by electrophoresis were checked against the reference spectrophotometric method based on Berthelot s reaction Sensitivity enhancements of this reference method were achieved by using a modified Berthelot reaction solenoid micro-pumps for liquid propulsion and a long optical path cell based on a liquid core waveguide (LCW) All techniques and methods of this work are in line with the green analytical chemistry trends (C) 2010 Elsevier B V All rights reserved

Continuous monitoring of ascorbate transport through neuroblastoma cells with a ruthenium oxide hexacyanoferrate modified microelectrode

The uptake of ascorbate by neuroblastoma cells using a ruthenium oxide hexacyanoferrate (RuOHCF)-modified carbon fiber disc (CFD) microelectrode (r = 14.5 mu m) was investigated. By use of the proposed electrochemical sensor the amperometric determination of ascorbate was performed at 0.0 V in minimum essential medium (MEM, pH = 7.2) with a limit of detection of 25 mu mol L(-1). Under the optimum experimental conditions, no interference from MEM constituents and reduced glutathione (used to prevent the oxidation of ascorbate during the experiments) was noticed. The stability of the RuOHCF-modified electrode response was studied by measuring the sensitivity over an extended period of time (120 h), a decrease of around 10% being noticed at the end of the experiment. The rate of ascorbate uptake by control human neuroblastoma SH-SY5Y cells, and cells transfected with wild-type Cu,Zn-superoxide dismutase (SOD WT) or with a mutant typical of familial amyotrophic lateral sclerosis (SOD G93A), was in agreement with the level of oxidative stress in these cells. The usefulness of the RuOHCF-modified microelectrode for in vivo monitoring of ascorbate inside neuroblastoma cells was also demonstrated.