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The overall theme of the research discussed in this dissertation has been to explore processing-structure-property relationships for submicron polymeric fibers produced by electrospinning (Part I) and to ascertain whether or not the length of the short chain branch has any effect on the physical properties of films of linear low-density polyethylenes (LLDPEs) (Part II). Electrospinning is a unique process to produce submicron fibers (as thin as 100 nm) that have a diameter at least two orders of magnitude smaller than the conventional fiber spinning processes based on melt and solution spinning. As a result, the electrospun fibers have a very high specific surface. The research efforts discussed in Part I of this dissertation relate to some fundamental as well as more applied investigations involving electrospinning. These include investigating the effects of solution rheology on fiber formation and developing novel methodologies to fabricate polymeric mats comprising of high specific surface submicron fibers of more than one polymer, high chemical resistant substrates produced by in situ photo crosslinking during electrospinning, superparamagnetic flexible substrates by electrospinning a solution of an elastomeric polymer containing ferrite nanoparticles of Mn-Zn-Ni and substrates for filtration applications. More specifically, it was found that the solution rheological parameters like concentration and viscosity, in addition to molecular weight play an important role in governing the fiber formation during electrospinning of polymer solutions. Furthermore, it was found that fiber formation depends strongly on the solution concentration regime, i.e., at low and dilute concentrations, droplets and beaded fibers were formed whereas uniform fibers were observed to form at a solution concentration greater than at least six times than that of the critical chain overlap concentration, c*, for linear homopolymers of poly(methyl methacrylate) that had molecular weight distributions ranging from 1.03-1.35 (Mw/Mn). In contrast, uniform fibers were observed at ten times the value of c* for the relatively broader molecular weight polymers (Mw/Mn~1.6-2.1). Novel methodologies were developed to in situ photocrosslink the electrospun jet to produce a crosslinked network in the form of a submicron fiber that could potentially be utilized for applications where a high resistance to chemical environments is required. In addition, flexible superparamagnetic substrates were developed by electrospinning a solution of an elastomeric polymer containing magnetic nanoparticles based on "mixed" ferrites of Mn-Zn-Ni where the specific saturation magnetization and the magnetic permeability of these substrates were found to increase linearly with the wt% loading of the nanoparticles. The methodology to simultaneously electrospin two polymer solutions in a side-by-side fashion was developed to produce bicomponent fibers with the rationale that the resulting electrospun mat will have properties from a combination from each of the polymer components. Bicomponent electrospinning of poly(vinyl chloride)- polyurethane and poly(vinylidiene fluoride)-polyurethane was successfully performed. In addition, filtration properties of single and bicomponent electrospun mats of polyacrylonitrile and polystyrene were investigated. Results indicated lower aerosol penetration or higher filtration efficiencies of the filters based on submicron electrospun fibers in comparison to the conventional filter materials. In addition, Part II of this dissertation explores whether or not the length of the short chain branch affects the physical properties of blown and compression molded films of LLDPEs that were synthesized by a single site metallocene catalyst. Here, three resins based on copolymers of ethylene/1-butene, ethylene/1-hexene, and ethylene/1-octene were utilized that were very similar in terms of their molecular weight and distribution, melt rheology, density, crystallinity and short chain branching content and its distribution. Interestingly, at higher deformation rates (ca. 1m/s), the breaking, tear and impact strengths of films based on ethylene/1-hexene and ethylene/1-octene were found to be superior than those based on ethylene/1-butene. While the origin of these differences in mechanical properties with increasing short chain branch length was not fully understood, the present investigation did confirm this effect to be pronounced only at high deformation rates for both the blown and compression molded LLDPE films. / Ph. D.

Osteoarthritis is the most prevalent musculoskeletal disease in humans, severely reducing the standard of living of millions of people. Osteoarthritis is characterized by degeneration and loss of articular cartilage which leads to pain, and loss of joint motility and function. Individuals suffering from severe osteoarthritis are commonly treated with full knee replacements. The procedure does eliminate the problem of degrading cartilage tissue; however, it does not fully restore function and its lifetime can be limited. To overcome the disadvantages of current treatments, tissue engineering has become a focus of research to regenerate cartilage. Tissue engineering attempts to repair or replace damaged tissue with cells, biomaterials, and/or molecular signals. Biodegradable scaffolds serve as a temporary replacement for the tissue until it has regenerated. Two types of scaffolds that have been used in tissue engineering are electrospun scaffolds and hydrogels. We have proposed and fabricated a scaffold for cartilage tissue engineering that incorporates an electrospun cylinder and a thermosetting hydrogel in order to provide improved properties compared to either individual material. Electrospun cylinders were created by sintering electrospun mats that include salt pores. The addition of salt pores decreased the mechanical properties of the electrospun materials while also improving the capability of cells to infiltrate into the scaffold. The sintering process involved the connecting of one electrospun mat to an adjacent one. Specifically, poly(d,l-lactide) was capable of sintering to an adjacent electrospun mat when exposed to either heat (near the glass transition temperature) or tetrahydrofuran vapor. The sintering process did not deteriorate the structure or function of the electrospun material. Sintering allowed the creation of unique structures of electrospun material that previously could not be produced. A thermosetting hydrogel was added to the scaffold to replicate the function of proteoglycans present in articular cartilage. A composite scaffold of electrospun polymer and hydrogel showed improved mechanical properties and better integration of the scaffold in vivo compared to an electrospun scaffold with no hydrogel. In conclusion, the composite electrospun and hydrogel scaffold could become an excellent tissue engineering scaffold to treat patients suffering from osteoarthritis. / Ph. D.

The solution rheological and electrospinning behavior of a series of charge-containing polymers, surface-active agents, and carbon nanotube composites was studied to investigate the effect of intermolecular interactions, including electrostatic interactions, hydrogen bonding, surface activity, and surface functionalization of carbon nanotubes. The synthesis of novel polyelectrolytes with varied topologies, charge content, and counterions tailored the charged macromolecules to elucidate structure-rheology and structure-processing relationships. In addition, the use of additives for electrospinning, including surfactants and nanofillers, allows us to tailor the functionality of electrospun nanofibers for high-performance applications. Novel polyelectrolytes based on poly(2-(N,N-dimethyl)aminoethyl methacrylate) (DMAEMA) were synthesized with the counteranions Cl-, NO3-, (CN)2N-, BF4-, PF6-, triflate (TfO-), and bis(trifluoromethanesulfonyl)imide (Tf2N-). The counteranion selection controlled the thermal transitions and degradation; the larger and more charge-delocalized anions typically resulted in lower Tg and higher decomposition temperature. The polyelectrolyte behavior in solution was nearly independent of anion choice, though solution conductivity depended on the electrophoretic mobility of the counterion. Charge containing copolymers of DMAEMA and di(ethylene glycol) methyl ether methacrylate (MEO2MA) were synthesized and demonstrated that polyelectrolyte behavior in solution was also nearly independent of charge content. Low ionic contents resulted in extended solution conformations and high conductivities. Controlled atom-transfer radical polymerization allowed the synthesis of star-shaped polyelectrolytes with varying arm numbers and lengths. The solution behavior of the stars deviated slightly from the linear polyelectrolytes due to significant counterion condensation within the star core and constrained polymer conformations. The linear and star-shaped polyelectrolytes were electrospun to understand the interplay between polyelectrolyte structure and electrospinnability. Similar to other strong polyelectrolytes described in the literature, PDMAEMA-based polyelectrolytes with polar anions (e.g. Cl-) experienced significant instabilities during electrospinning, requiring high concentrations and viscosities to stabilize the electrospinning jet. The use of large, more hydrophobic anions (BF4-, TfO-) led to increased electrospinnability. Unlike neutral branched polymers, which electrospin nearly identically to linear polymers of similar molecular weight, the star-shaped PDMAEMA-based polyelectrolytes required even higher viscosities than linear polyelectrolytes for stable electrospinning. The correlations between electrospinnability and solution rheological analysis are detailed. The use of surfactants facilitates the electrospinning of neutral polymers at lower concentrations. However, we have demonstrated that specific cylindrical aggregates of surfactants (wormlike micelles) can be electrospun into microfibers under the proper conditions. Ammonium and phospholipids surfactants as well as organogelators were studied using solution rheology and DLS to determine the effects of micellar structure and solution viscosity on the electrospinnability of low molar mass surfactants. In addition, the effects of charged and uncharged surfactants on the electrospinning behavior of poly(methyl methacrylate) were determined. Added surfactant facilitated uniform fiber formation at lower PMMA concentrations. XPS analysis demonstrated the formation of core-shell fibrous structures resulting from the self-migration of surfactants to the fiber surface. Hydrogen bonding also influences fiber formation through electrospinning. Star-shaped poly(D,L-lactide)s (PDLLAs) were end-functionalized with adenine (A) or thymine (T) units. The complementary hydrogen bonding between the adenine and thymine lead to thermoresponsive rheological behavior for mixtures of PDLLA-A and PDLLA-T. The mixtures could be electrospun above the hydrogen bond dissociation temperature and resulted in thicker fibers compared to unfunctionalized PDLLA stars. The hydrogen bonding allows the preparation of polymers with a combination desirable solid-state properties and very low processing viscosities. The effects of carbon nanotube incorporation on electrospinning behavior and fiber morphology were also investigated. Nonfuntionalized and carboxylic-acid functionalized carbon nanotubes were electrospun into polyurethane nanofibers. The nonfunctionalized nanotubes required high-shear melt mixing to disperse within the polyurethane, but remained well dispersed through electrospinning. The surface functionalization with acid groups produced nanotubes which dispersed more readily into the polyurethane solutions. TEM analysis revealed that nanotube dispersion and alignment within the nanofibers was similar for both nonfunctionalized and acid-functionalized nanotubes. / Ph. D.

Skeletal loss and bone deficiencies are major worldwide problem that is only expected to increase due to increase in aging population. As current standards in treatment autografts and allografts are not without drawbacks, there is a need for alternative bone grafts substitutes. The goal of this project was to utilize electrospinning and heat sintering techniques to create biodegradable full thickness three dimensional biomimetic polymeric scaffolds with macro and nano architecture similar to natural bone for bone tissue engineering. First we have investigated pretreatment with 0.1M NaOH and electrospinning gelatin/PLLA blends as means to increase overall mineral precipitation and distribution throughout the scaffolds when incubated in concentrated simulated body fluid (SBF)10XSBF. Mixture of 10% gelatin and PLLA resulted in the significantly higher degree of mineralization, increased mechanical properties, and scaffolds that supported cellular adhesion and proliferation. In the next step we applied heat sintering technique to fabricate 3D electrospun scaffolds that were used to evaluate effects of mineralization and fiber orientation on scaffold strength. Fiber orientation can make a slight difference in nanofibrous scaffold compressive mechanical properties, but this difference is not as profound as the difference seen with increased mineralization. We also developed a technique to fabricate scaffolds that mimic the organization of an osteon, the structural unit of cortical bone. Resulting scaffolds consisted of concentric layers of electrospun gelatin/PLLA nanofibers wrapped around microfiber core with diameters that ranged from 200-600µm. Individual osteon-like scaffolds were heat sintered to fabricate three dimensional scaffolds contained a system of channels running parallel to the length of the scaffolds, as found naturally in bone tissue. Finally we combined two previously fabricated structures, sintered electrospun sheets and individual osteon-like scaffolds, to create novel scaffolds that mimic dual structural organization of natural bone with cortical and trabecular regions. Mineralization for 24 hr significantly increased mechanical properties of the scaffolds, both yield stress and compressive modulus under physiological conditions. Both nonminerlized and mineralized scaffolds were found to support cellular attachment and proliferation over 28 days in culture, but scaffolds mineralized for 24hr were found to better support osteoblastic differentiation and mineral deposition. / Ph. D.

This thesis presents a melt electrospinning technique to fabricate highly porous and controllable poly (ε-caprolactone) (PCL) microfibers for tissue engineering applications and rehabilitation applications. Electrospinning without solvents via melt methods may be an attractive approach to tissue engineering of cell constructs where solvent accumulation or toxicity is an issue. This method is also able to produce microfibers with controllable parameters. However, the fiber diameters resulting from melt electrospinning processes are relatively large when compared to the fibers from solution electrospinning. The typical microfiber diameter from melt electrospinning was reported to be approximately 0.1mm. In order to further develop the melt electrospinning technique, we focused on the design of a melt electrospinning setup based on numerical analysis using the Solidworks 2013 simulation package and practically established a melt electrospinning setup and thermal control system for accurate experiments. One of main purposes of this thesis is the build-up of mathematical modeling to control and predict the electrospun microfiber via a more intricate understanding of their parameters such as the nozzle diameter, applied voltage, distance between the nozzle and counter electrode, temperature, flow rate, linear transitional speed, among others. The model is composed of three parts: 1) melt electrospinning process modeling, 2) fibrous helix movement modeling, and 3) build-up of microfibers modeling. The melt electrospinning process model describes an electric field, the shape of jet’s continuously changing shape, and how the polymer melt is stretched into a Taylor cone and a straight jet. The fibrous helix movement model describes movement of electrospun microfibers influenced by Lorentz force, which moves along the helix pattern. Lastly, the build-up microfiber modeling describes the accumulation of the extruded microfibers on both flat and round counter electrodes based on the physical forces involved. These models are verified by experimental data from our own customized melt electrospinning setup. Moreover, the fabricated scaffolds are tested by seeding neural progenitors derived from murine R1 embryonic stem cell lines and it demonstrates the potential of scaffolds for tissue engineering applications. To increase cell attachment and proliferation, highly porous microfibers are fabricated by combination of melt electrospinning and particulate leaching technique. Finally, auxetic stretchable PCL force sensors are fabricated by melt electrospinning for hand rehabilitation. These stretchable sensors can be used to measure applied external loads or displacement and are also attachable to various substrates. We have attempted to apply the sensors to real human hand in order to prove their functionality. / Graduate / jko@me.uvic.ca

Head and neck squamous cell carcinomas (HNSCC) are among the leading causes of cancer related deaths throughout the world. The survival rate for this type of cancer is extremely low and has not changed significantly in recent decades. There is an imperative need to study tumor progression in a representative model in order to generate more knowledge about this disease as well as develop more effective treatment options. Multiple methods already exist for studying HNSCC and other types of cancers, including in vitro and in vivo models. Although in vivo models are more representative of the human carcinomas in terms of complexity of the microenvironment the tumor cells experience, they are difficult to manipulate and many experiments cannot be performed easily in whole organisms; therefore, in vitro models are used. Current in vitro models are typically two-dimensional (2D) monolayer cultures that are easily manipulated for a controlled environment, but these fail to mimic the native microenvironment in terms of three-dimensional (3D) interactions present in vivo. The literature documents that several 3D organotypic models of HNSCC have been created, showing significant differences in tumor response to drugs between these models and traditional 2D culture systems, perhaps suggesting a closer representation of human HNSCC. However, these models were not rigorously validated, with little comparison to in vivo tumor behavior. We developed a 3D HNSCC in vitro model using electrospun scaffolds to mimic the extracellular matrix as well as using a HNSCC-derived tumor cell line, HN12, in co-culture with a supporting fibroblast cell line. We compared the model to the same tumor cell line grown in vivo in immunodeficient mice. We also investigated drug sensitivity of tumor cells in our model compared to conventional monocultures to determine whether differences exist. Finally, we investigated pro-angiogenic properties of tumor cells in this model. The long-term goal is to develop a model that can be manipulated easily to study tumorigenic mechanisms and potential treatments.

Les interfaces entre deux fluides sont le siège de nombreuses instabilités de forme de l’interface si un champ électrique intense est appliqué : génération de gouttelettes, jets micrométriques, etc. Le contrôle de telles instabilités est indispensable pour une fabrication optimale de microsphères ou microfibres : taille, propriétés physico-chimiques, dispersion et structuration spatiale macroscopique d’un agrégat de tels objets. Cette diversité provient de la compétition entre la tension de surface et la gravité avec l’électrodynamique des fluides sous champ électrique induite par les charges électriques, les charges de polarisation, les décharges électriques et/ou le vent ionique. La thèse expérimentale s’articule autour de deux thèmes. Le premier, une compréhension intime des phénomènes spatio-temporels observables lorsqu’un injecteur métallique à la haute tension placé au-dessus d’un bain. Une instabilité originale menant à la formation d’une cloche fluide macroscopique connectant les deux électrodes a été mise en évidence et caractérisée non linéairement. La bifurcation est sous-critique et imparfaite. Le second thème propose une méthode originale de fabrication de microfibres modifiées en une étape par électrofilage au mouillé. Le polymère électrofilé choisi est le PSMA et celui permettant la modification, le PEGDA. Cette étude a été réalisée dans un contexte d’applications de type catalyse. Pour cela les fibres ont été fonctionnalisées à l’aide de la peroxydase (HRP) comme protéine modèle. Les résultats montrent notamment une meilleure stabilité temporelle avec la possibilité de réutilisation du matériau en comparaison à la catalyse utilisant des méthodes standards. / Interfaces between two fluids can lead to various interfacial shape instabilities if an electrical field is applied. Leading, for instance, to micrometric droplets or jets formation. Controlling those instabilities is much-needed for an optimal fabrication of microspheres or microfibers : size, physicochemical properties, dispersion and macroscopic spatial structuring of aggregates of those kind of objects. This diversity is based in the competition between surface tension and gravity forces with gravity during the electrodynamics of fluids under electric field induced by electrical charges, polarization charges, electrical discharges and ionic wind. The experimental thesis deals with two main topics. The first one is a precise understanding of spatiotemporals phenomena occurring in a configuration made of a metallic injector raised to high voltage placed above a liquid bath. We present the formation of an original instability leading to a macroscopic bell-shaped link between both electrodes and its non linear characterization. The bifurcation is subcritical and imperfect. The second topic, based on the experience gained with the first one, is an original method of fabrication of microfibers modified in only one step by wet electrospinning. The chosen electrospun polymer is PSMA and the one used for modification is PEGDA. This study has been realized with a catalyze application context. To do so, fibers has been functionalized with peroxydase (HRP) as the model protein. The results especially show a better temporal stability and possible reuse compared to catalysis with standard methods.

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2017-09-29T01:08:32Z No. of bitstreams: 1 Andressa_G_Rosenberger_2017.pdf: 2187152 bytes, checksum: eeb5c275b57d9c489c86178a66925400 (MD5) / Made available in DSpace on 2017-09-29T01:08:32Z (GMT). No. of bitstreams: 1 Andressa_G_Rosenberger_2017.pdf: 2187152 bytes, checksum: eeb5c275b57d9c489c86178a66925400 (MD5) Previous issue date: 2017-03-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Estado do Paraná (FA) / Water is a vital element in human health and a determining factor in the pace of human evolution; however, the presence of emerging pollutants threatens its quality and may endangers the well-being of people and the environment. This work stands out for the development of a composite material based on nanotechnology to be used as an electroanalitic sensor in aqueous solutions with the Metronidazole drug which is considered an emerging pollutant. Initially the polymeric fibers were produced based on ecovio® and carbon nanotubes multilayer (MWCNT’s). In order to evaluate the parameters that could interfere in the process of electrospinning and to understand the interaction between the polymer and the MWCNT’s, a fractional factorial design and physicochemical characterizations analysis were used, which were: optical micrography scanning electron microcopy (SEM), mechanical analysis, wettability by contact angle, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DSC) and X-ray diffraction. For the porpuse of fabricating the sensor, the fibers were calcinated and the obtained residue was characterized by SEM and FTIR. The statistical data and the images of optical microscopy and SEM showed that the addition of MWCNT’s is the parameter that most influences the diameter of the obtained microfibers (1.16 ± 0.22 µm) so that their presence decreases the diameter and results in fibers more uniform and homogeneous. After selecting the ideal conditions an experiment was done with the following process and solution parameters: concentration of ecovio® 15,00% (m/v) and MWCNT’s 0,60% (m/v); flow: 1.80 mL.h-1; distance: 16 cm and applied voltage: 18 kV. The morphology and diamater os the fibers was obtained using SEM images and showed an average diameter of 1.59±0.61 µm. It was also demonstrated a better mechanical performance after the addition of MWCNT’s to the fibers, so that they presented greter elasticity (180%) and significant increase on the elastic resistance (163%) and tensile strength (107%), besides the analysis of wettability from the contact angle suggest that the carbon-based nanomaterial is inside the polymeric microfibers. The interactions between the MWCNT’s and the polymer were better evaluated by vibracional aspects by Fourier transform infrared spectroscopy (FTIR) and showed the interaction between the MWCNT’s and the functional group C=O characteristic of the group ester of the polymers. The analysis of thermogravimetry (TGA) demonstrated a higher stability. The thermogravimetric analysis (TGA) showed a higher stability of the poly (lactic acid) component and lower resistances of the poly (butylene adipate co-terephtalate) component in the polymer blend. Besides it was necessary a constant temperature of 550 ºC during 50 minutes to the total degradation of the polymer. By differential thermal analysis (DSC) it was possible to confirm the interactions proposed by FTIR and TGA, which indicate that the interaction occurs preferentially with the aliphatic chains of the ecovio® polymer. After the calcination of the fibers, the obtained residue was characterized by FTIR and MEV and variations in the characteristics of pure MWCNT's can be observed, with reduction of the corboxylic groups for the calcined and electrospun/calcined MWCNT's, as well as the formation of lamella for the MWCNT's electrospun/calcined. The electrochemical measurements using the cyclic voltammetry technique showed that the sensor is promising for determination of Metronidazole. / A água é um elemento vital e determinante no ritmo da evolução humana, contudo a presença de poluentes emergentes ameaça sua qualidade e põe em risco o bem estar humano e ambiental. O presente trabalho destaca-se por desenvolver um material compósito formado por poli (butileno adipato co-tereftalato) (PBAT) e poli (ácido lático) (PLA) para ser utilizado como sensor eletroanalítico em soluções aquosas contendo o fármaco metronidazol. Inicialmente produziu-se fios poliméricos a base de ecovio® e nanotubos de carbono de paredes múltiplas (MWCNT’s). A fim de avaliar os fatores interferentes do processo e compreender a interação entre o polímero e os MWCNT’s utilizou-se um planejamento fatorial fracionário e análises de caracterização físico-química tais como: micrografia ótica, microscopia eletronica de varredura (MEV), análise mecanica, molhabilidade por angulo de contato, espectroscopia vibracional de infravermelho por transformada de Fourrier, análise termogravimétrica (TGA), calorimetria exploratória diferencial (DSC) e difratometria de raio X (DRX).Para a construção do sensor eletroquímico as fibras foram calcinadas e o resíduo obtido foi caracterizado pelas ténicas de MEV e FTIR. Os resultados estatísticos em conjunto com as imagens de microscopia ótica e MEV demonstram que a adição de MWCNT’s é o parâmetro que mais influência no diâmetro das microfibras (1,16 ± 0,22 µm) obtidas, de modo, que sua inserção diminui este parâmetro deixando as fibras mais uniformes e homogêneas. Após a escolha das condições ideais procedeu-se um experimento com os seguintes parâmetros da solução e do processo de eletrofiação: ecovio® 15,00% (m/v) e MWCNT’s 0,60% (m/v); fluxo: 1,80 mL.h-1; distância: 16 cm e tensão: 18 kV. A morfolagia e o diâmetro das fibras foram realizadas usando as imagens de MEV e apresentam diâmetro médio de 1,59±0,61 µm. Foi evidenciado também um melhor desempenho mecanico após a inserção de MWCNT’s às fibras de modo que as fibras apresentam maior elasticidade (180%) e um aumento significativo da resistência elástica (163%) e tensão de ruptura (107%). Ademais a análise de molhabilidade por ângulo de contato sugere que o nanomaterial a base de carbono encontra-se no interior das microfibras poliméricas. As interações entre o MWCNT’s e os polímeros foram melhor avaliadas pelos espectros vibracionais de infravermelho por transformada de Fourrier (FTIR) e evidenciam a interação entre MWCNT’s e o grupamento funcional C=O, característicos dos grupamentos ésteres dos polímeros. As análises de termogravimetria (TGA) demonstram uma maior estabilidade do componente poli (ácido lático) e uma menor estabilidade do poli (butileno adipato co-tereftalato) na blenda polimérica, além disso, foi necessário uma temperatura constante de 550 ºC durante 50 minutos para degradar totalmente o polímero.Pela análise térmica diferencial (DSC) foi possível confirmar as interações propostas pelo FTIR e TGA, que indicam que a interação ocorre preferencialmente com as cadeias alifáticas do polímero ecovio®. Após a calcinação das fibras, para o preparo do sensor, o resíduo obtido foi caracterizado por FTIR e MEV e pode-se observar mudanças na caracteristica dos MWCNT’s puros com diminuição dos grupos carboxilicos para os MWCNT’s tratados termicamente e eletrofiados/calcinados, além da formação de lamelas para o MWCNT’s eletrofiados/calcinados. As medidas eletroquímicas usando a tecnica de voltametria cíclica, mostram que o sensor é promissor para determinação de metronidazol.