Cellulose nanofibers (CNFs) have established widespread attention in various industries with their potential applications. Production of CNFs from agricultural post harvesting wastes has several cost-effective and eco-friendly benefits. The objective of this research was to prepare four different types of CNFs from cotton stalks by different chemical treatments followed by ultra-sonication. CNFs via untreated bleached pulp, sulfuric acid hydrolysis, and TEMPO [(2,2,6,6-tetramethylpiperidin-1-yl) oxy radical]-mediated oxidation process were produced. Physical and chemical properties of these CNFs were investigated by morphological (FE-SEM, AFM), structural (FTIR), and thermal gravimetric analysis (TGA). Developed TEMPO-oxidized cellulose nanofibers (TEMPO-CNFs) were brighter and higher in yields (>90%). It was the first time uniform and very small sized (3-15 nm diameter and 10-100 nm length) nanofibers were produced. In application purpose, TEMPO-CNFs were introduced into chitosan matrix (prepared from shrimp exoskeletons) for the development of bionanocomposite food packaging films and into chitin for hydrogels preparation in order to eliminate heavy metals from water bodies. Development of bionanocomposite films (chitosan/TEMPO-CNFs compositions) was an effective and complete green approach with enhanced mechanical and barrier properties. Also use of TEMPO-CNFs in this method makes it possible to produce flexible, transparent, and low cost food packaging films with good antimicrobial activity against Salmonella enterica, E. coli O157:H7, and Listeria monocytogenes. In a similar way, generation of recyclable biobased adsorbents (chitin/TEMPO-CNFs compositions) with superior adsorption capacity and high surface area were effectively used in lead (Pb2+) removal from aqueous solutions, thus provide new opportunities as economical and environmentally friendly green remediation.

Les composés dits 'bionano' (bionanocomposites) apparaissent comme un nouveau groupe de matériaux hybrides nano-structurés. Ils sont issus de la combinaison de polymères naturels et de solides inorganiques et sont de l'ordre du nanomètre dans au moins une direction. Ces matériaux hybrides conservent les structures et les propriétés fonctionnelles des polymères et matériaux inorganiques dont ils sont composés. Parallèlement, la présence de biopolymères permet de diminuer les risques environnementaux et de santés publiques liés aux nano-matériaux. Les propriétés inhérentes aux biopolymères (biocompatibles' et biodégradables) ouvrent des perspectives intéressantes pour ces matériaux hybrides en particulier dans les domaines de la médecine regénérative et en génie de l'environnement. La production de bionanocomposites de taille plus importante, que les nanoparticules qu'ils renferment, permet d'éviter les effets nocifs potentiels des nanoparticules (NPs) pour les organismes vivants et plus particulièrement pour l'homme. L'association de biopolymères et de nano-solides inorganiques permet la conception de bionanocomposites multifonctionnels qui peuvent être synthétisés et utilisés pour des applications dans des domaines variés. Cette thèse se propose d'étudier principalement (i) ma présence d'arsenic et d'antibiotiques dans les sources d'eau potable en Chine; (ii) l'évaluation d'un nouveau bionanocomposites, à savoir le CGB (chitosan goethite bionanocomposite), dans la décontamination des eaux contenant des espèces inorganiques d'arsenic; (iii) l'évaluation d'argiles comme adsorbants de décontamination de la gentamicine (un antibiotique aminoglycoside ) présent dans l'eau de même que celle de bionanocomposés fait d'argiles riches en gentamicine de polymères de methycelluloses hydroxypropyles Gt-Mt-HPMC (gentamicin-montmorillonite- hydroxypropyl methycellulose) utilisés comme pansement contre les infections qui ont lieu suite à des brûlures. / Bionanocomposites represent an emerging group of nano-structured hybrid materials. They are formed by the combination of natural polymers and inorganic solids and show at least one dimension on the nanometer scale (Darder et al., 2007). These hybrid materials retain the structural and functional properties of nano-structured materials. Meanwhile, the presence of biopolymer can reduce the public health and environmental risk of nano-sized material. The properties inherent to the biopolymers, that is, biocompatibility and biodegradability, open new prospects for these hybrid materials with special incidence in regenerative medicine and in environmental engineering (Darder et al., 2007). Fabrication of large-sized bionanocomposites, rather than nano-sized particles, can prevent possible harmful nanoparticles (NPs) intake by humans and living things. Synergistic assembling of biopolymers with inorganic nano-sized solids leads to multifunctional bionanocomposites which can be synthesized and applied in several areas for designed purposes. This thesis focuses on (i) the presence of toxic arsenic and antibiotics in Chinese drinking water sources; (ii) evaluation of a novel tailored bionanocompsite, namely chitosan goethite bionanocomposite (CGB), as removal agent for inorganic arsenic species from water; (iii) using clay mineral as adsorbent for removing gentamicin, an aminoglycoside antibiotic, from water, and assembling gentamicin-loaded clay with biopolymer hydroxypropyl methycellulose leading to a bionanocomposites film, namely gentamicin-montmorillonite- hydroxypropyl methycellulose (Gt-Mt-HPMC), to be used as burn wound dressing.

Cette thèse présente un travail sur l’obtention d’aérogels d’HDL par séchage en conditions CO2 supercritique et l’élaboration de nouveaux bionanocomposites formés par la coprécipitation d’hydroxydes doubles lamellaire (HDL) dans l'espace confiné des billes d'alginate. Grâce à la combinaison d’une synthèse par coprécipitation Flash et d’un séchage en conditions supercritiques au CO2, des aérogels d’HDL possédant des surfaces spécifiques élevées sont élaborés. Parallèlement, l’alginate est utilisé comme une matrice de confinement pour la précipitation inorganique d’HDL. D’une part, les billes d'alginate sont synthétisées par complexation des ions Ca2+ et la coprécipitation des phases HDL s’effectue en réalisant des imprégnations successives de réactifs. D’autre part, des billes d'alginate sont formées directement en présence des cations divalents (Mg2+, Ni2++, Co2+, ...) et des cations des métaux trivalents (Al3+), précurseurs des composés inorganiques. La coprécipitation des HDL se produit dans ce cas lors d'une étape d'imprégnation dans une solution d'hydroxyde de sodium. Tous les composés HDL, aérogels ou encore bionanocomposites sont caractérisés en détail par DRX, spectroscopie IR, MEB/MET, adsorption/désorption d’azote et ATG/DTG, pour obtenir un meilleur aperçu de la structure des particules, de leur taille et de leur morphologie. Des études menées sur l’adsorption de la trypsine pour les aérogels ou encore sur les performances d’électrodes modifiées HDL-alginate ont permis de montrer qu’il était possible d'améliorer les performances des HDL en augmenter leur porosité et en élaborant des bionanocomposites. / In this work, we investigated both the use of CO2 supercritical drying conditions and the use of biopolymer to modify the growth and aggregation of inorganic Layered Double Hydroxide (LDH) particles. Indeed, one possibility to enhance their performances is to increase the LDH porosity and to design them as nanostructured open structure. Thanks to the combinaison of fast coprecipitation and CO2 supercritical drying, highly porous LDH aerogels were obtained with enhanced textural properties. In parallel, the coprecipitation of Layered Double Hydroxides (LDH) in the confined space of alginate beads is reported. In our approach, Alginate acts as a template to support and confined the inorganic precipitation. In one hand, beads made of Alginate are synthesized by complexation of Ca2+ ions and LDH phases are coprecipitated using successive impregnations of reactants. In another hand, Alginate beads are formed directly in presence of the divalent (Mg2+, Ni2+, Co2+,…) and trivalent metal cations (Al3+), precursors of the inorganic compounds. LDH coprecipitation then occurs during a further impregnation step in a sodium hydroxide solution. All the LDH aerogels and LDH nanocomposites beads are deeply characterized using XRD, SEM/TEM, FTIR spectroscopic, adsorption/desorption of nitrogen and TGA/DTG to get better insight on particle structure, size and morphology Aerogels display enhanced adsorption behavior toward trypsine immobilization whereas a net improvement of the electrochemical response is noticed for the NiAl based bionanocomposites prepared by confined coprecipitation into Alginate.

Orientador: Marcia Regina de Moura Aouada / Resumo: Diante da crescente preocupação com os impactos ambientais relacionados ao uso de polímeros sintéticos, estudos visando à obtenção e aplicação de materiais poliméricos de fontes renováveis vêm aumentando, como por exemplo, o desenvolvimento de filmes comestíveis à base de polímeros naturais. Para a obtenção de filmes comestíveis necessita-se de um material polimérico que forme uma matriz homogênea e contínua. A gelatina é um polímero natural, de fonte abundante, biodegradável e biocompatível e tais características motivam sua utilização como matriz em filmes comestíveis. O uso de extrato de chá-verde e óleo essencial de limão em filmes de gelatina é uma alternativa para melhoria de suas características físicas e organolépticas para uma aplicação inovadora do produto como sachê de chá. Neste contexto, o objetivo do presente estudo foi preparar, caracterizar e avaliar a influência do extrato de chá-verde e da nanoemulsão de limão nas propriedades de solubilidade, mecânicas, térmicas e de permeabilidade ao vapor de água da matriz de gelatina. A nanoemulsão apresentou tamanho médio de 171 ± 3 nm e potencial zeta de -10,9 ± 0,1 mV. Os filmes foram obtidos por casting a partir de soluções filmogênica de gelatina com extrato de chá verde e nanoemulsão de limão. A adição de chá verde ocasionou um aumento da tensão máxima de ruptura do filme de gelatina de 86 ± 7 MPa para 101 ± 5 MPa e quando a nanoemulsão foi adicionada o valor diminuiu para 78 ± 8 MPa. A incorporação de chá-verde e ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In view of the growing concern about the environmental impacts related to the use of synthetic polymers, studies aimed to obtain and apply polymeric materials from renewable sources have been increased, as the development of edible films based on natural polymers. To obtain edible films, a polymeric material is needed to form a homogeneous and continuous matrix. Gelatin is a natural polymer, from an abundant source, biodegradable and biocompatible and such characteristics motivate its use as a matrix in edible films. The use of green tea extract and lemon essential oil in gelatin films is an alternative to improve its physical and organoleptic characteristics for an innovative application of the product as a tea bag. In this context, the objective of the present study was to prepare, characterize and evaluate the influence of the green tea extract and the lemon nanoemulsion on the solubility, mechanical, thermal and water vapor permeability properties of the gelatin matrix. The nanoemulsion had an average size of 170.6 ± 3 nm and a zeta potential of -10.9 ± 0.1 mV. The films were obtained by casting from filmogenic solutions of gelatin with green tea extract and lemon nanoemulsion. The addition of green tea caused an increase in the maximum tensile stress of the gelatin film from 86 ± 7 MPa to 101 ± 5 MPa and when the nanoemulsion was added the value decreased to 78 ± 8 MPa. The incorporation of green tea and nanoemulsion increased the permeability of water vapor and the solu... (Complete abstract click electronic access below) / Mestre

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Clay minerals have historically played a consequential role in human health. While the beginnings were rooted in geophagy, a primitive act of consuming earth, the health-related uses of clay minerals have evolved and diversified over time. As excipients in pharmaceutical formulations, clay minerals can attribute novel properties onto intercalated compounds. Intercalating oxybenzone, a UV filter, within the interlamellar space of montmorillonite is desirable in order to minimize direct contact with skin. Intercalating resveratrol, a compound known for attributing beneficial effects onto human health, may be advantageous since this compound is susceptible to cis-trans isomerisation. The strategy of using alkylammonium–modified clay was undertaken and proved successful for the intercalation of oxybenzone. The field of biopolymer/layered silicate nanocomposites is heavily researched for use in a multitude of applications. Novel montmorillonite nanocomposites were prepared with neutral guar gum and cationic guar gum, using an environmentally friendly process and are fully characterized.

Clay minerals have historically played a consequential role in human health. While the beginnings were rooted in geophagy, a primitive act of consuming earth, the health-related uses of clay minerals have evolved and diversified over time. As excipients in pharmaceutical formulations, clay minerals can attribute novel properties onto intercalated compounds. Intercalating oxybenzone, a UV filter, within the interlamellar space of montmorillonite is desirable in order to minimize direct contact with skin. Intercalating resveratrol, a compound known for attributing beneficial effects onto human health, may be advantageous since this compound is susceptible to cis-trans isomerisation. The strategy of using alkylammonium–modified clay was undertaken and proved successful for the intercalation of oxybenzone. The field of biopolymer/layered silicate nanocomposites is heavily researched for use in a multitude of applications. Novel montmorillonite nanocomposites were prepared with neutral guar gum and cationic guar gum, using an environmentally friendly process and are fully characterized.

Cette thèse présente un travail sur l'obtention d'aérogels d'HDL par séchage en conditions CO2 supercritique et l'élaboration de nouveaux bionanocomposites formés par la coprécipitation d'hydroxydes doubles lamellaire (HDL) dans l'espace confiné des billes d'alginate. Grâce à la combinaison d'une synthèse par coprécipitation Flash et d'un séchage en conditions supercritiques au CO2, des aérogels d'HDL possédant des surfaces spécifiques élevées sont élaborés. Parallèlement, l'alginate est utilisé comme une matrice de confinement pour la précipitation inorganique d'HDL. D'une part, les billes d'alginate sont synthétisées par complexation des ions Ca2+ et la coprécipitation des phases HDL s'effectue en réalisant des imprégnations successives de réactifs. D'autre part, des billes d'alginate sont formées directement en présence des cations divalents (Mg2+, Ni2++, Co2+, ...) et des cations des métaux trivalents (Al3+), précurseurs des composés inorganiques. La coprécipitation des HDL se produit dans ce cas lors d'une étape d'imprégnation dans une solution d'hydroxyde de sodium. Tous les composés HDL, aérogels ou encore bionanocomposites sont caractérisés en détail par DRX, spectroscopie IR, MEB/MET, adsorption/désorption d'azote et ATG/DTG, pour obtenir un meilleur aperçu de la structure des particules, de leur taille et de leur morphologie. Des études menées sur l'adsorption de la trypsine pour les aérogels ou encore sur les performances d'électrodes modifiées HDL-alginate ont permis de montrer qu'il était possible d'améliorer les performances des HDL en augmenter leur porosité et en élaborant des bionanocomposites.

Clay minerals have historically played a consequential role in human health. While the beginnings were rooted in geophagy, a primitive act of consuming earth, the health-related uses of clay minerals have evolved and diversified over time. As excipients in pharmaceutical formulations, clay minerals can attribute novel properties onto intercalated compounds. Intercalating oxybenzone, a UV filter, within the interlamellar space of montmorillonite is desirable in order to minimize direct contact with skin. Intercalating resveratrol, a compound known for attributing beneficial effects onto human health, may be advantageous since this compound is susceptible to cis-trans isomerisation. The strategy of using alkylammonium–modified clay was undertaken and proved successful for the intercalation of oxybenzone. The field of biopolymer/layered silicate nanocomposites is heavily researched for use in a multitude of applications. Novel montmorillonite nanocomposites were prepared with neutral guar gum and cationic guar gum, using an environmentally friendly process and are fully characterized.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta dissertação, foram estudadas a preparação e a caracterização debionanocompósitos à base de gelatina e magnetita. Sacarose foi empregada comoagente de reticulação e gelatina tipo A e gelatina tipo B foram comparadas nautilização para a preparação das microesferas por meio de emulsão água-em-óleo.As microesferas foram caracterizadas por VSM, DSC, TGA, FTIR, testes deinchamento, espectroscopia de absorção atômica, microscopia ótica e microscopiaeletrônica de varredura. Um planejamento de experimentos variando-se aconcentração de gelatina e de sacarose, a temperatura e a velocidade de agitaçãofoi realizado a fim de encontrar quais parâmetros influenciam o diâmetro dasmicroesferas. A concentração de gelatina e velocidade de agitação foram osparâmetros diretamente associados com os tamanhos de partículas. A distribuiçãode tamanho das partículas revelou que o diâmetro das microesferas variou de 5 a 60micrômetros, com predominância na faixa de 11 a 30 micrômetros. A extensão dareticulação foi aumentada com o aumento do tempo de aquecimento na etapa depreparação das microesferas. Todos os bionanocompósitos apresentaramsuperparamagnetismo. Os resultados mostraram que não há diferença significativa entre a utilização de gelatina do tipo A e gelatina do tipo B. Além disso, o estudo de reticulação degelatina revelou que, ao contrário do que diz a literatura, a sacarose não é umagente de reticulação para as cadeias proteicas, pois não foram encontradasevidências de uma reação química entre a sacarose e gelatina / The preparation and characterization of microbeads based on gelatin and magnetite are reported. Sucrose was employed as crosslinking agent and type A gelatin and type B gelatin were compared for preparation of microspheres by water-in-oil emulsion. The microbeads were characterized by VSM, DSC, FTIR, swelling ratio, atomic absorption spectroscopy and optical and scanning electronic microscopy. The influence of gelatin and sucrose concentration, temperature and stirring speed on the microbeads characteristics was studied. The gelatin concentration and stirring speed were the parameters directly associated with the particle sizes. The particle size distribution revealed that the diameter of the microspheres ranged from 5 to 60 micrometers, with predominance in the range from 11 to 30 micrometers. The extent of cross linking increased as a function of preparation heating time periods. The microbeads presented superparamagnetism. The results show that have no significant difference between the utilization of type A gelatin and type B gelatin. In addition, the gelatin crosslinking study revealed that sucrose is not a crosslinking agent because there was no evidence of chemical reaction between sucrose and gelatin