<p>Zein is a major storage protein of corn, with unique amphiphilic film forming properties. It is insoluble in water, but soluble in 70% ethanol and acetic acid, and has been declared ‘generally recognized as safe’ (GRAS) by the FDA. Due to new advances in food nanotechnology, zein is being investigated for various applications such as biodegradable packaging, oral delivery of proteins and peptides, scaffold for tissue engineering, as well as biodegradable sensor platforms. The time consuming and highly complicated methods for toxin and allergen analysis in the food industry necessitates the need for a rapid, selective, compact and easy-to-use method of detection for analytes. In the scope of this dissertation, we investigated the feasibility of functional zein nanocomposite films and formation of a zein nanocomposite sensor assembly for rapid and highly selective electrochemical measurements of food toxins and allergens. Fabrication of a zein based electrochemical amperometric sensor assembly was studied, first through the comparison of various zein film characteristics changes with the application of Laponite®, graphene oxide and carbon nanotube nanoparticles, followed by a proof-of-concept study by detecting the gluten allergen protein gliadin. </p> <p>To mechanistically study the functional zein nanocomposite films, Laponite®, a silica nanoparticle, was added in the presence of 70% ethanol solvent and oleic acid plasticizer. The films were studied using various characterization techniques like transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), water contact angle measurements etc. Through Si-N bond formation between Laponite® and zein, fabricated zein nanocomposite films showed increase in surface hydrophobicity, water vapor barrier properties, tensile strength and Young’s modulus. Graphene oxide (GO), a carbon nanoparticle, was also incorporated into zein through the solvent casting process. Uniform dispersion of GO nanoparticles within zein matrix were confirmed up to 1% GO loading, and covalent and hydrogen bonding mechanisms were proposed. Similar to zein-Laponite® (Z-LAP) nanocomposites, zein-GO (Z-GO) showed increase in hydrophobic tendencies, rougher surface and a 300% improvement in Young’s modulus and 180% improvement in tensile strength at only 3% GO loading. Both nanoparticles increased tensile strength, thermal stability and water vapor barrier property of the films, indicating a potential for food packaging as an alternative application for the nanocomposite films.</p> Finally, the research focused on the fabrication of an electrochemical amperometric sensor, capable of detecting the protein gliadin, which is responsible for the allergic reaction with people having celiac disease. Novel biodegradable coatings made from zein nanocomposites: zein-graphene oxide, zein-Laponite® and zein-multiwalled carbon nanotubes (Z-CNT) using drop casting technique were tested for fabricating the electrochemical sensors using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV) techniques. As Z-CNT produced the strongest signals compared to other nanomaterials, the active tip of the electrochemical sensor was functionalized through a sequence of layer by layer deposition of Z-CNT nanocomposite, antibody and target analyte. Here, Z-CNT acts as a natural linker molecule with large number of functional groups, that causes immobilization of capture antibody and target, to ensure high sensor performance. Both CV curves and SWV curves indicated successful sequential immobilization of gliadin antibody onto the Z-CNT coated electrode. The Z-CNT biosensor was successfully able to give CV signals for gliadin toxins for as low as 0.5 ppm and was highly specific for gliadin in the presence of other interfering molecules, and remained stable over a 30-day period. The low-cost, thin, conductive zein films offered a promising alternative for protein immobilization platforms used in sensors and can be extended to other matrices in biosensors as well as other functional film applications

Among the next generation materials being investigated for membrane development, partially reduced Graphene Oxide (rGO) has received increasing attention from the membrane community. rGO-based nanofiltration membranes have shown promising results in applications such as partial desalination, organic contaminant removal, gas-phase separations, and separations from solvent media. rGO offers a unique platform compared to common polymeric membranes since it can be used for separation applications in both aqueous and organic solvent media. An rGO-based platform could also be utilized to synthesize reactive membranes, giving rGO membranes the additional capability of reactively removing organic contaminants. This research focuses on the synthesis of rGO and nanocomposite membranes for applications including the separation of high-value phenolic compounds from a solvent-water mixture, removal of organic contaminants, and treatment of refinery wastewater. First, the behavior of a rGO membrane in water and isopropanol was investigated along with its ability to separate high-value, lignin-derived oligomeric compounds from a solvent-water mixture. This study revealed the formation of stable sorbates of water in the GO channels that resulted in declined membrane permeance and improved size-exclusion cutoff. Through controlled reduction of GO by heat treatment, it was demonstrated that physicochemical properties of the GO membrane could be modulated and separation performance tuned based on the extent of reduction. A varying degree of interlayer spacing was attained between the GO laminates by controlling the O/C ratio of GO. This allowed the rGO membrane to achieve tunable molecular separation of lignin-derived model oligomeric compounds from a solvent-water mixture. Second, the mechanism of ionic transport through the rGO membrane was studied as well as its application in partial desalination and removal of persistent organic contaminants from water. Through comprehensive experimental investigations and mathematical analysis, along with the aid of the extended Nernst Planck equation, the impacts of steric hindrance and charge interactions on the underlying ion transport mechanism were quantified. Charge interactions were observed to be the dominant exclusion mechanism for the rGO membranes. The application of rGO membranes for treatment of high TDS produced water was investigated with the goal of partial hardness and dissolved oil removal. In addition, this study demonstrated the removal of emerging organic contaminants, specifically perfluorooctanoic acid, by rGO membranes and elucidated a charge interaction-dominated exclusion mechanism for this contaminant, as well. Finally, rGO-based and microporous polyvinylidene fluoride (PVDF)-based catalytic membrane platforms were synthesized for removal of organic contaminants via an oxidative pathway. Herein, an advanced oxidation process was integrated with membrane technology by the in-situ synthesis of Fe-based nanoparticles. The unique capability to oxidatively remove contaminants in a continuous mode of operation was explored in addition to the separation performance of the membrane. The rGO-based platform achieved high oxidative removal of trichloroethylene via a sulfate-free, radical-mediated pathway, while simultaneously removing humic acids from water and potentially eliminating undesired side reactions. A PVDF-based microporous catalytic membrane platform was shown to effectively remove organic impurities, such as Naphthenic acids, from high TDS produced water by the same pathway. The enhancement of reaction extent for elevated temperatures and longer residence times was also quantified in this study. These studies benefit the membrane community in the following ways: 1) The work identifies the critical role of the physicochemical properties of GO, such as the O/C ratio and water sorption, for determining the permeability-selectivity of rGO membranes for solvent nanofiltration. 2) Investigations of ion transport through rGO membranes led to an understanding of a charge-dominated separation mechanism for ion retention. The Nernst-Planck equation-based approach employed in this study would enable further assessment and comparison of rGO membranes under a wide set of parameters. 3) Catalytic membrane platforms (rGO and microporous PVDF-based) were synthesized for conducting advanced oxidation reactions in the porous membrane domain, demonstrating potential applications in environmental remediation of organic contaminants.

L'objectif de la thèse est d'expérimenter et de valider de nouvelles voies d'exfoliation des feuillets de graphène dans des élastomères de type silicone (PDMS) et des thermoplastiques de type polyéthylène (PE). Ce projet s'appuie sur des étapes de modifications chimiques des feuillets de graphite oxydé (GO) dont la polarité initiale n'offre pas une compatibilité satisfaisante avec les matrices étudiées. Différentes approches ont été explorées : la synthèse du GO greffé PDMS a été réalisée avec succès par greffage directe d'un PDMS fonctionnalisé triéthoxysilane et par une réaction d'hydrosilylation catalytique de GO modifiés vinyltriméthoxysilane en présence de polyméthylhydrogénosiloxane. Une étude des propriétés viscoélastiques de suspensions de GO et GO modifié/PDMS a montré l'importance de l'interaction charge-charge sur la formation d'un réseau percolant. Le seuil de percolation rhéologique du GO a été obtenu à 1,75 %wt avec Af~60. En se basant sur le greffage radicalaire du pentadécane par abstraction d'atomes d'H par un peroxyde à haute température, il a été possible d'extrapoler cette réaction pour procéder au greffage d'un PE de faible masse molaire (Mn~2000). De plus, des PE fonctionnalisés thiol et azoture de Mn similaire ont aussi été greffés sur des dérivés du graphite par addition radicalaire et de Michael. Après sélection d'une charge présentant une conductivité en poudre proche du graphite et une bonne affinité pour les milieux alcanes, un nano-composite à base de PEBD présentant des propriétés électriques convenables pour une application de blindage électromagnétique (4.105 Ω.cm à 25%wt) a été réalisé et ceci sans utiliser d'agents réducteurs toxiques / The aim of this thesis was to experiment and validate new means of graphene exfoliation in an elastomer matrix such as silicone (PDMS) and a thermoplastic matrix such as polyethylene (PE). Because of the low affinity of graphene oxide for these matrices due to its high polarity, its chemical modification was carried out. Different approaches were explored: the grafting of PDMS onto GO was carried out with success by a direct functionalization with a PDMS terminated triethoxysilane and by a catalytic hydrosilation reaction of a PDMS terminated Si-H onto vinyltrimethoxysilane modified GO. The viscoelastic behavior of GO and modified GO/PDMS suspensions showed the importance of the filler-filler interaction on the formation of a percolating network. The rheological percolation threshold of the GO/PDMS suspension was obtained at ~1.75 wt% with an aspect ratio (Af) of ~60. In addition, the grafting of PE onto GO was studied with the high temperature radical grafting of pentadecane formed by a hydrogen atom abstraction with a peroxide, which was then extrapolated to a low molecular PE (Mn~2000). Moreover, thio and azide functionnalized PE with a similar Mn were also grafted onto graphite derivatives by a radical and a Michael addition. After choosing the filler which presented the closest electrical conductivity to the one of graphite powder and a good affinity for a heptane media, a LDPE based nano-composite that presented suitable electrical properties for an electromagnetic shielding application (4 105 Ω.cm at 25 wt%) was obtained and this without any use of toxic reducing agents

A common method of cancer treatment is radiation therapy. In radiation therapy, a treatment planning system is made to specify the dose of X-rays needed to eradicate the tumor. To assure the right amount of X-ray dosage a quality assurance is using a phantom containing radiation sensors. The sensors are made of semiconductor materials with heavy metal-based contacts. Irradiating heavy elements with a high-intensity beam such as Xrays causes secondary scattering of electrons, resulting in an additional photocurrent which may distort the signal used in the quality analysis. By exchanging the heavy-metal contact material to a lighter version such as a carbon-based material, preventing secondary scattering, the error obtained from the quality analysis can be minimized.In this thesis, characterization of contacts between radiation diodes and a copper substrate by flip-chip bonding with reduced graphene oxide-based anisotropic conducting adhesive is made. The parameters of the connections are characterized with respect to electrical, thermal and mechanical properties.Analysis of the novel contact material is done by comparing different types of graphene-based anisotropic fillers with a commercial metal-based filler. Results obtained indicate that it is possible to exchange the metal-based fillers in an anisotropic conducting adhesive with reduced graphene oxide coated polymer spheres as a contacting material for radiation sensing technology. / En vanlig metod som används för att behandla cancer är strålningsterapi. I strålningsterapi görs ett behandlingsplaneringssystem för att specificera en exakt dos av röntgenstrålning som krävs för att slå ut en tumör. För att säkerställa att man ger rätt dos av röntgenstrålning utförs en kvalitetssäkring genom att använda en fantom innehållande strålningssensorer. Sensorerna är gjorda av halvledarmaterial men har oftast anslutningar gjorda av tunga metalliska material. När man bestrålar metaller med hög intensitet, exempelvis röntgenstrålning, emitteras en sekundär spridning av elektroner i form av en fotoström som kan störa signalen i kvalitetsäkrningen. Genom att byta ut metallen som används i anslutningarna till ett kontaktmaterial med lägre atomnummer som exempelvis kolbaserade material, förhindras den sekundära spridningen av elektroner, som troligtvis minskar felet som uppstår vid kvalitetssäkringen.I detta arbete har en kartläggning av kontakter mellan stålningsdioder och ett kopparsubstrat, genom en flip-chip-bindning process med ett ledande adhesiv baserat på reducerad grafenoxid gjorts. Kontaktparametrarna som kartlagts är baserade på termiska, elektriska och mekaniska egenskaper.Kartläggningen av kontakterna har i mestadels gjort genom att jämföra olika typer av grafen baserade partiklar ett kommersiellt metalbaserat material gjort för flip-chipbindning. Resultaten från arbetet indikerar att det är möjligt att byta ut det metallbaserade partiklarna i ett anisotropt ledande adhesiv med reducerade grafenoxid-belagda polymersfärer som ett ledande material för strålningsapplikationer.

Lasers are increasingly used for a wide range of different applications for both civil and military purposes. Due to the distinct properties of laser light, use of lasers often comes with a risk of damage to the human eye and other optical sensors. Therefore, an effective laser protection is needed. 2D-materials is a relatively new class of materials, which have shown to possess many unique properties compared to its bulk counterparts. Some 2D-materials exhibit nonlinear optical (NLO) properties, and specifically optical power limiting (OPL) effects, and have therefore been researched for laser protection applications. In this work, two different 2D-materials, MXene Ti3C2 and graphene oxide (GO), have been combined with a hybrid organic-inorganic polymer, a so called melting gel (MG), to synthesise nanocomposites possessing OPL effects for laser protection applications. Different methods of incorporating the 2D-materials in the polymer matrix as well as the effect on optical properties of different concentrations of 2D-materials were investigated. The prepared nanocomposites were characterised using optical microscopy, spectroscopy and OPL measurements in order to investigate and quantify their linear and nonlinear optical properties. The MG was optically clear, mechanically stable and easy to synthesise, which makes it a suitable candidate as a matrix for a laser protection nanocomposite. Additionally, it was possible to dope the MG with the two different 2D-materials to create nanocomposites showing desirable optical properties in the visible spectrum. However, many samples showed signs of clustered 2D-particles indicating that the dispersion could be improved. Finally, OPL measurements, performed at 532 nm, showed that the MG itself exhibited OPL effects, both 2D-materials showed a stronger OPL effect than the non-doped MG and that GO-doped samples gave a better protection than the MXene samples.

For the past few decades, the popularity of graphene oxide (GO) nanomaterials (NMs) has increased exceedingly due to their biomedical applications in drug delivery of anti-cancer drugs. Their unique physicochemical properties such as high surface area and good surface chemistry with unbound surface functional groups (e.g. hydroxyl - OH, carboxyl /ketone C=O, epoxy/alkoxy C-O, aromatic group C=C, etc) which enable covalent bonding with organic molecules (e.g. RNA, DNA) make GO NMs as excellent candidates in drug delivery nanocarriers. Despite the overwhelming biomedical applications, there are concerns about their genotoxicity on human DNA. Published genotoxicity studies on GO NMs were performed using non-commercial GO with 2-3 layers of GO sheets, synthesized in various laboratories with the potential for inter-laboratory variabilities. However, what has not been studied before is the effects of the commercial GO (15-20 sheets; 4-10% edge-oxidized; 1 mg/mL) in vitro on DNA damage in human whole blood and peripheral blood lymphocytes (PBL) from real-life patients diagnosed with chronic pulmonary diseases [asthma, chronic obstructive pulmonary disease (COPD), and lung cancer], and genotoxic endpoints compared with those from healthy control individuals to determine whether there are any differences in GO sensitivity. Thus, in the present study, we had characterized GO NMs using Zetasizer Nano for Dynamic Light Scattering (DLS) and zeta potential (ZP) in the aqueous solution, and electron microscopy using the Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) in the dry state, respectively. Cytotoxicity studies were conducted on human PBL from healthy individuals and patients (asthma, COPD, and lung cancer) using the Methylthiazolyldiphenyl-tetrazolium bromide (MTT) and Neutral Red Uptake (NRU) assays, respectively. The genotoxicity (DNA damage) and cytogenetic effects (chromosome aberration parameters) induced by GO NMs on human whole blood from healthy individuals and patients were studied using the Alkaline Comet Assay and Cytokinesis-blocked Micronucleus (CBMN) assay, respectively. Our results showed concentration-dependent increases in cytotoxicity, genotoxicity, and chromosome aberrations, with blood samples from COPD and lung cancer patients being more sensitive to DNA damage insults compared with asthma patients and healthy control individuals. Furthermore, the relative gene and protein expressions of TP53, CDKN1A/p21, and BCL-2 relative to GAPDH on human PBL were studied using the Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR) and Western Blot techniques, respectively. Our results have shown altered gene and protein expression levels. Specifically, GO-induced cytotoxicity, genotoxicity, and micronuclei aberrations were associated with TP53 upregulation - a biomarker of DNA damage - in both patients and healthy individuals. These effects show that GO NMs have promising roles in drug delivery applications when formulated to deliver drug payload to COPD and cancer cells. However, the fact that cytotoxicity, genotoxicity, chromosome instability, and gene/protein expressions - biomarkers of cancer risk - were observed in healthy individuals are of concern to public health, especially in occupational exposures at micro levels at the workplace.

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[ES] Para abordar los desafíos ambientales, la química y los procesos químicos deben ser más sostenibles. Para ello, el desarrollo de nuevos catalizadores especialmente activos es de suma importancia. En catálisis heterogénea, el grafeno ha surgido recientemente como un excelente candidato desde que fue posible aislarlo a partir del grafito. Sus propiedades únicas han despertado un gran interés para aplicarlo en varios campos, desde el refuerzo de matrices poliméricas hasta el desarrollo de materiales para catálisis. En catálisis, su uso como soporte catalítico o como carbocatalizador es todavía objeto de varios estudios. Con el objetivo de preparar catalizadores extremadamente activos en varias reacciones de química fina o de producción de hidrógeno, nuestro trabajo de investigación se ha centrado en el uso de materiales a base de grafeno como soportes catalíticos. Se consideraron diferentes aspectos: La funcionalización del grafeno; al ser un material de baja dimensionalidad, las propiedades del grafeno están estrechamente relacionadas con la química de su superficie. Mediante la fosforilación del óxido de grafeno, hemos demostrado que la estabilidad térmica y la estabilización de las nanopartículas metálicas mejoran significativamente. La combinación de grafeno con otros materiales; Pequeñas nanopartículas de paladio estabilizadas sobre materiales porosos a base de óxido de grafeno y quitosano han demostrado una excelente actividad para la deshidrogenación del formiato de amonio. La estrategia de síntesis adoptada para preparar el grafeno; La pirólisis de películas de alginato de amonio y un precursor de rutenio (Ru) en diferentes atmósferas permitió la preparación de nanopartículas de Ru soportadas en grafeno cuya orientación depende de la atmósfera de pirólisis. Por lo tanto, fue posible una comparación de la actividad catalítica de diferentes facetas cristalográficas. Dopaje de grafeno; la presencia de diferentes heteroátomos en su estructura ha permitido una mejor estabilización de nanopartículas y clusters metálicos. Los materiales basados en nanopartículas de óxido de cobre y grafenos dopados han demostrado poseer una excelente actividad catalítica en la síntesis de nuevas moléculas de interés farmacéutico. / [CA] Per a abordar els desafiaments ambientals, la química i els processos químics han de ser més sostenibles. Per a això, el desenvolupament de nous catalitzadors especialment actius és de summa importància. En catàlisi heterogènia, el grafé ha sorgit recentment com un excel·lent candidat des que va ser possible aïllar-lo a partir del grafit. Les seues propietats úniques han despertat un gran interés per a aplicar-lo en diversos camps,des del reforç de matrius polimèriques fins al desenvolupament de materials per a catàlisis. En catàlisi, el seu ús com a suport catalític o com carbocatalitzador és encara objecte de diversos estudis. Amb l'objectiu de preparar catalitzadors extremadament actius en diverses reaccions de química fina o de producció d'hidrogen, el nostre treball de recerca s'ha centrat en l'ús de materials a base de grafé com a suports catalítics. Es van considerar diferents aspectes: La funcionalització del grafé; a l'ésser un material de baixa dimensionalitat, les propietats del grafé estan estretament relacionades amb la química de la seua superfície. Mitjançant la fosforilació de l'òxid de grafé, hem demostrat que l'estabilitat tèrmica i l'estabilització de les nanopartícules metàl·liques milloren significativament. La combinació de grafé amb altres materials; Xicotetes nanopartícules de pal·ladi estabilitzades sobre materials porosos a base d'òxid de grafé i quitosà han demostrat una excel·lent activitat per a la deshidrogenació del formiat d'amoni. L'estratègia de síntesi adoptada per a preparar el grafé; La piròlisi de pel·lícules de alginat d'amoni i un precursor de ruteni (Ru) en diferents atmosferes va permetre la preparació de nanopartícules de Ru suportades en grafé, l'orientació del qual depén de l'atmosfera de piròlisi. Per tant, va ser possible una comparació de l'activitat catalítica de diferents facetes cristal¿logràfiques. Dopatge de grafé; la presència de diferents heteroàtoms en la seua estructura ha permés una millor estabilització de nanopartícules i clústers metàl·lics. Els materials basats en nanopartícules d'òxid de coure i grafens dopats han demostrat posseir una excel·lent activitat catalítica en la síntesi de noves molècules d'interés farmacèutic. / [EN] To address environmental challenges, chemistry and chemical processes need to be more sustainable. For this, developing new particularly active catalysts is of paramount importance. In heterogeneous catalysis, graphene has emerged as an excellent candidate since it was possible to isolate it from graphite. Its properties have aroused substantial interest, earning it applications in various fields spanning from the reinforcement of polymer matrices to the development of materials for catalysis. In catalysis, its use both as a catalytic support or as a carbocatalyst is still the subject of several studies. Aiming to prepare extremely active catalysts in various fine chemical reactions or hydrogen production, our research work has focused on the use of graphene-based materials as catalytic supports. Different aspects were considered: The functionalization of graphene; being a material of low dimensionality, the properties of graphene are intimately related to the chemistry of its surface. Through phosphorylation of graphene oxide, we have shown that the thermal stability and stabilization of metal nanoparticles are significantly improved. Combination of graphene with other materials; small palladium nanoparticles stabilized on porous materials based on graphene oxide and chitosan have demonstrated excellent activity for the dehydrogenation of ammonium formate. The synthetic strategy adopted to prepare graphene; pyrolysis of films of ammonium alginate and ruthenium precursor (Ru) in different atmospheres enabled the preparation of Ru nanoparticles supported on graphene whose orientation depends on the atmosphere of pyrolysis. Thus, a comparison of the catalytic activity of different crystallographic facets was possible. Doping of graphene; the presence of different heteroatoms in its structure has allowed a better stabilization of metal nanoparticles and clusters. Materials based on copper oxide nanoparticles and tridoped graphene have demonstrated an excellent catalytic activity in the synthesis of new molecules of pharmaceutical interest. / Anouar, A. (2021). Préparation de matériaux à base de graphène et leur application en catalyse [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/164030