Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-10-09T11:38:28Z No. of bitstreams: 2 Dissertação - Anielle Carvalho Bandeira - 2016.pdf: 3728087 bytes, checksum: 11425e90569d00c562e5046dfd39fd10 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-10-09T12:50:00Z (GMT) No. of bitstreams: 2 Dissertação - Anielle Carvalho Bandeira - 2016.pdf: 3728087 bytes, checksum: 11425e90569d00c562e5046dfd39fd10 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-10-09T12:50:00Z (GMT). No. of bitstreams: 2 Dissertação - Anielle Carvalho Bandeira - 2016.pdf: 3728087 bytes, checksum: 11425e90569d00c562e5046dfd39fd10 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-09-16 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Nanotechnology involves the creation and use of materials, devices and systems through control of matter on the manometer scale. It has positive impact on medicine involving the treatment and diagnosis. Drug delivery systems prepared with nanostructures have the ability to overcome biological barriers and optimizing drug release. However, one of the main challenges in the use of these systems is their internalization by macrophages. This study aims to prepare and characterize polymer nanoparticles formed by biodegradable polymers and investigate its impact on the function of macrophages in vitro by the observation of cell viability, phagocytic activity and cytokine production. Also, was investigate the cytokine profile in serum and splenocytes culture supernatant from Balb/C mice injected with chitosan nanoparticles. The chitosan and chitosan-containing magnetic nanoparticles were prepared by ionic gelation crosslinking, resulting in a morphology "nearly spherical" and positive zeta potential. The PLGA prepared by emulsification and solvent evaporation method presented spherical morphology and negative zeta potential. All preparations had a diameter smaller than 300 nanometers and polydispersity index lower than 0.5. Nanoparticles of chitosan and PLGA affected the viability of macrophages in vitro only at the highest concentration tested (4 mg/mL). The chitosan nanoparticles containing magnetic nanoparticles were internalized by macrophages after 4h and 24h of incubation. Different nanoparticles triggered high production of TNF- and low IL12p40 production and IL-10. Serum and splenocytes culture supernatant was observed in both the production of IFN- as IL-4. However, IL-4 production was higher than that of IFN-. / A nanotecnologia envolve a criação e utilização de materiais, dispositivos e sistemas através do controle da matéria na escala manométrica. Apresenta impactos positivos na medicina que envolve desde o diagnóstico ao tratamento de doenças. Sistemas de entrega de fármacos apresentam a capacidade de superar barreiras biológicas e otimizar a liberação de um fármaco. No entanto, um dos principais desafios na utilização desses sistemas é a sua internalização pelos macrófagos. Esse estudo objetiva preparar e caracterizar nanopartículas poliméricas formadas por polímeros biodegradáveis e investigar o seu impacto na função dosmacrófagos in vitro através da observação da viabilidade celular, atividade fagocítica e produção de citocinas. Além do perfil de citocinas no soro e sobrenadante de cultura de esplenócitos provenientes de camundongos Balb/C que foram injetados com uma suspensão de nanopartículas de quitosana. As nanopartículas de quitosana e quitosana contendo magnéticas foram preparadas por gelificação iônica apresentando morfologia reticular e “quase esférica”, respectivamente, e potencial zeta positivo. As de PLGA preparadas por emulsificação e evaporação do solvente apresentaram morfologia esférica e potencial zeta negativo. Todas apresentaram diâmetro menor que 300 nanômetros e índice de polidispersão menor que 0,5. As nanopartículas de quitosana e de PLGA afetaram a viabilidade de macrófagos in vitro apenas na maior concentração testada (4mg/mL). As nanopartículas de quitosana contendo magnética foram internalizadas pelos macrófagos em 4h e 24h de incubação. As diferentes nanopartículas desencadearam a produção elevada de TNF- e baixa produção de IL12p40 e IL-10. No soro e no sobrenadante da cultura de esplenócitos foi observada tanto a produção de INF- quanto de IL-4. No entanto, a produção de IL-4 foi maior que a de IFN-.

As diversas aplicações tecnológicas de nanopartículas magnéticas (NPM) vêm intensificando o interesse por materiais com propriedades magnéticas diferenciadas, como magnetização de saturação (MS) intensificada e comportamento superparamagnético. Embora MNP metálicas de Fe, Co e bimetálicas de FeCo e FePt possuam altos valores de MS, sua baixa estabilidade química dificulta aplicações em escala nanométrica. Neste trabalho foram sintetizadas NPM de Fe, Co, FeCo e FePt com alta estabilidade química e rigoroso controle morfológico. NPM de óxido metálicos (Fe e Co) também foram obtidas. Dois métodos de síntese foram empregados. Usando método baseado em sistemas nanoheterogêneos (sistemas micelares ou de microemulsão inversa), foram sintetizadas NPM de Fe3O4 e Co metálico. Foram empregados surfactantes cátion-substituídos: dodecil sulfato de ferro(III) (FeDS) e dodecil sulfato de cobalto(II) (CoDS). Para a síntese das NPM, foram estudados e determinados a concentração micelar crítica do FeDS em 1-octanol (cmc = 0,90 mmol L-1) e o diagrama de fases pseudoternário para o sistema n-heptano/CoDS/n-butanol/H2O. NPM esferoidais de magnetita com3,4 nm de diâmetro e comportamento quase-paramagnético foram obtidas usando sistemas micelares de FeDS em 1-octanol. Já as NPM de Co obtidas via microemulsão inversa, apesar da larga distribuição de tamanho e baixa MS, são quimicamente estáveis e superparamagnéticas. O segundo método é baseado na decomposição térmica de complexos metálicos, pelo qual foram preparadas NPM esféricas de FePt e de óxidos metálicos (Fe3O4, FeXO1-X, (Co,Fe)XO1-X e CoFe2O4) com morfologia controlada e estabilidade química. O método não mostrou a mesma efetividade na síntese de NPM de FeAg e FeCo: a liga FeAg não foi obtida enquanto que NPM de FeCo com estabilidade química foram obtidas sem controle morfológico. NPM de Fe e FeCo foram preparadas a partir da redução térmica de NPM de Fe3O4 e CoFe2O4, as quais foram previamente recobertas com sílica. A sílica previne a sinterização inter-partículas, além de proporcionar caráter hidrofílico e biocompatibilidade ao material. As amostras reduzidas apresentaram aumento dos valores de MS (entre 21,3 e 163,9%), o qual é diretamente proporcional às dimensões das NPM. O recobrimento com sílica foi realizado via hidrólise de tetraetilortosilicato (TEOS) em sistema de microemulsão inversa. A espessura da camada de sílica foi controlada variando-se o tempo de reação e as concentrações de TEOS e de NPM, sendo então proposto um mecanismo do processo de recobrimento. Algumas amostras receberam um recobrimento adicional de TiO2 na fase anatase, para o qual foi empregado etilenoglicol como solvente e ligante para formação de glicolato de Ti como precursor. A espessura da camada de TiO2 (2-12 nm) é controlada variando as quantidades relativas entre NPM e o precursor de Ti. Ensaios de hipertermia magnética foram realizados para as amostras recobertas com sílica. Ensaios de hipertermia magnéticas mostram grande aumento da taxa de aquecimento das amostras após a redução térmica, mesmo para dispersões diluídas de NPM (0,6 a 4,5 mg mL-1). Taxas de aquecimento entre 0,3 e 3,0oC min-1 e SAR entre 37,2 e 96,3 W g-1. foram obtidos. A atividade fotocatalítica das amostras recobertas foram próximas à da fase anatase pura, com a vantagem de possuir um núcleo magnético que permite a recuperação do catalisador pela simples aplicação de campos magnéticos externos. Os resultados preliminares dos ensaios de hipertermia magnética e fotocatálise indicam um forte potencial dos materiais aqui relatados para aplicações em biomedicina e em fotocatálise. / The most diverse technological applications of magnetic nanoparticles (MNP) have intensifiedthe interest for materials with different magnetic properties such as enhanced saturationmagnetization (MS) and superparamagnetic behavior. Despite the high MS values of metalparticles of Fe, Co, FeCo and FePt, their low chemical stability hinders most applications at thenanoscale. This thesis reports the synthesis of metallic Fe and Co and bimetallic FeCo and FePtMNP with high chemical stability and strict morphological control. MNP of iron oxide and mixediron-cobalt oxide were also synthesized. Two methods were employed. The first method, basedon nanoheterogeneous systems (micellar or reverse microemulsion systems), was used toprepare magnetite and metallic Co NPM. The method applies cation-substituted surfactants:iron(III) dodecyl sulfate iron (FeDS) and cobalt(II) dodecyl sulfate (CoDS). Before the MNPsyntheses, it were studied e determined the critical micelle concentration of FeDS in 1-octanol(cmc = 0.90 mmol L-1) and the pseudo-ternary phase diagram of n-heptane/CoDS/nbutanol/H2O. Spheroidal MNP of magnetite with 3.4 nm in diameter and quasi-paramagneticbehavior were prepared in octanolic FeDS micellar systems. Despite their broad sizedistribution and low MS, metallic Co MNP were produced in reverse microemulsions withchemical stability and superparamagnetic behavior. The second synthesis method, based onthermal decomposition of metal complexes, was employed to prepare spherical FePt and metaloxides (Fe3O4, FeXO1-X, (Co, Fe)XO1-X and CoFe2O4) MNP. Strict morphological control and highchemical stability were reached. Such method does not show the same effectiveness tosynthesize FeAg and FeCo MNP: the FeAg bimetallic alloy was not obtained while FeCo MNPwith chemical stability and compositional control were prepared with no morphological control.Fe and FeCo MNP were produced by thermal reduction of silica-coated Fe3O4 and CoFe2O4 MPN. The coating, beyond to prevent inter-particle sintering, provides biocompatibility andhydrophilic character. The reduced samples showed a significant increase in MS values(between 21.3 and 163.9%), which is directly proportional to MNP size. The silica coating wasaccomplished by tetraethylorthosilicate (TEOS) hydrolysis in reverse microemulsions. Thethickness of the silica layer is controlled by varying the reaction time and concentration of TEOSand NPM. The observations during coating process allowed to propose its probable mechanism.An additional coating of TiO2 (anatase phase) was performed onto silica layer for somesamples. Anatase coating was achieved by using ethylene glycol as both solvent and ligand toproduce an intermediate complex Ti precursor. The variation of the relative amounts of NPMand the Ti precursor allows to control the thickness of the anatase layer between 2 and 12 nm. Assays of magnetic hyperthermia were performed for silica-coated samples. The heating rate of the reduced samples increases after thermal reduction, even for dilute MNP dispersions (0.6 to4.5 mg mL-1). Heating rates between 0.3 and 3.0o C min-1 and SAR in the range of 37.2 96.3 Wg-1 were obtained. The photocatalytic activities of pure anatase particles and TiO2 -coated MNPwere close, but the magnetic samples has the advantage of being recovered from reactionmedia by applying the external magnetic fields. The preliminary results of magnetichyperthermia and photocatalysis assays indicate such materials have strong potential forapplications in biomedicine and photocatalysis.

Made available in DSpace on 2014-07-29T15:07:09Z (GMT). No. of bitstreams: 1 Dissertacao Harley Fernandes Rodrigues.pdf: 5566711 bytes, checksum: 484423a034c8d6a3a3f34650b5036af1 (MD5) Previous issue date: 2011-08-23 / In this work we developed a Dip Coating method that could control the temperature gradient between a substrate and the material that one wants to adsorb at its surface. In particular, the adsorption of biocompatible magnetic nanoparticles at the surface of bare metal Stents, under different experimental conditions, was investigated. The magnetic nanoparticles consisted of magnetite coated with tripoliphosphate (mean diameter 7.68 nm and standard deviation 1.88 nm) dispersed in water at physiological conditions, while the Stent was a CoCr based-one (Cronus stent from Scitech with 16 mm length). Nine series of experiments were performed where it was controlled parameters as: time of adsorption, stent temperature and magnetic fluid temperature. The stents coated with nanoparticles were magnetically characterized using a vibrating sample magnetometer (VSM), which allowed us to determine the number of nanoparticles at the stent surface. The increase of the magnetic moment of the stent with the increase of the adsorption time was theoretically modeled, with an excellent experimental agreement, as a transient diffusion process of nanoparticles at the interface stent-magnetic fluid, which clearly indicates an important diffusive contribution. Strong evidences of thermal diffusion (Soret effect), i.e. nanoparticle diffusion due to temperature gradient between the stent and the magnetic fluid, were shown, suggesting the possibility of nanostructures vectorization through thermal induced mechanisms. The spatial distribution of nanoparticles at the surface of the stent was investigated by Scanning Electron Microscopy (SEM) and X-ray Spectroscopy by Dispersive Energy (EDS). Measurements of the compositional mapping and images of SEM revealed that the nanoparticles are not homogeneously distributed, being concentrated at the edges of the stents for the experimental conditions investigated in this work. As the VSM data, the EDS of the stents revealed an increase of the quantity of adsorbed magnetic nanoparticles at the surface with the increase of the adsorption time. The same theoretical model, know considering the amount of 26Fe in the chemical composition of the coated stent, was able to explain the experimental data. Finally, a comparison was made, using the compositional mapping study of the coated stents, between the Dip Coating and the Spray technique. The later showed a more homogeneous distribution of nanoparticles at the surface of the stent, suggesting that this technique is more adequate on the development of a biomedical nanoproduct for clinical tests. / Neste trabalho foi desenvolvida uma técnica de Dip Coating (deposição por via líquida) que permite controlar o gradiente de temperatura entre o substrato e o material que se quer depositar em sua superfície. Em particular, foi investigado o efeito de adsorção de nanopartículas magnéticas biocompatíveis na superfície de Stents nus em diversas condições experimentais. As nanopartículas magnéticas consistiam de magnetita recobertas com tripolifosfato (diâmetro médio ) dispersas em água em pH fisiológico, enquanto as endopróteses eram Stents de CoCr (Stent Cronus da empresa Scitech com 16mm). Ao todo foram realizadas 9 séries de experimentos onde controlou-se parâmetros como: tempo de adsorção, temperatura do Stent e temperatura do fluido magnético. Os Stents recobertos com nanopartículas foram então caracterizados magneticamente pela técnica de magnetometria de amostra vibrante (VSM Vibrating Sample Magnetometer ), que permitiu determinar o número de nanopartículas magnéticas adsorvidas na superfície da endoprótese. O aumento do momento magnético do Stent com o aumento do tempo de adsorção foi modelado teoricamente, com grande concordância experimental, como um processo de difusão transiente de nanopartículas na interface Stent-fluido magnético, evidenciando a forte contribuição difusiva. Fortes evidências de efeitos termodifusivos (efeito de Soret), ou seja mecanismos de difusão mássica de nanopartículas devido ao gradiente de temperatura entre Stent e FM, foram apresentados, sugerindo a possibilidade de vetorização de nanoestruturas por meio de fenômenos termoinduzidos. A distribuição das nanopartículas na superfície dos Stents foi investigada por medidas de Microscopia Eletrônica de Varredura (MEV) e espectroscopia de raios-X por energia dispersiva (EDS). As medidas de mapeamento composicional e imagens de MEV revelaram que as nanopartículas estão distribuídas de maneira não homogênea, estando concentradas nas bordas dos Stents para as condições experimentais utilizadas neste trabalho. Assim como os dados de MAV, o EDS dos Stents recobertos revelou um aumento da quantidade de nanopartículas magnéticas adsorvidas em sua superfície com o aumento do tempo de adsorção. O mesmo modelo teórico, agora considerando o percentual de 26Fe na composição química do revestimento, foi capaz de explicar os dados experimentais. Finalmente, foi feita uma comparação, por meio do mapeamento composicional de Stents recobertos, entre as técnicas de Dip Coating e Spray. Esta última apresentou uma distribuição de nanopartículas mais homogênea na superfície da endoprótese, sugerindo que possa ser mais adequada para a confecção de um nanoproduto médico voltado a testes clínicos.

Made available in DSpace on 2014-07-29T15:10:32Z (GMT). No. of bitstreams: 1 Tese-Erika2009.pdf: 3993118 bytes, checksum: 2852e36019237acb54dcbae5e0aa2faf (MD5) Previous issue date: 2009-08-14 / Magnetic nanoparticles (MNPs) have been used in a great variety of biomedical applications, especially in cancer treatment, drug delivery, and diagnosis by magnetic resonance imaging. Embryonic stem cells (ESCs), due to its capacity of auto-renewal and differentiation in some types of cells, offer a great potential for its use in tissue regeneration and in alternative treatments for many degenerative diseases. The study had as aims: i) to evaluate in vitro citotoxicity of maghemite nanoparticles functionalized with lauric acid, DMSA, and citrate in human melanoma cells (SK-MEL-37) by the MTT assay, electronic microscopy, and DNA electroforesis by agarose gel; ii) to develop a culture system using the previously selected MNPs and a magnet to expand in vitro murine embryonic stem cells (mESCs) in the absence of a co-culture of murine embryonic fibroblasts (MEF) (the indifferentiated state of the mES was analyzed by alkaline phosphatase cytochemistry, electronic microscopy, and analysis of Oct-4 and Nanog gene expression by RT-PCR); iii) to isolate and expand ESCs from bovine blastocysts, and to characterize its pluripotency by analysis of Oct-4 and STAT-3 gene expression by RT-PCR. The MNPs coated with lauric acid, citrate, and DMSA showed no citotoxicity, judging by the high values of IC50 found (254, 433 and 2260 μg-iron/ml, respectively), and that the nanoparticles coated with citrate was chosen to expand the mESCs. The doubling time for the cells cultivated in the presence of MNPs was slightly higher than in the presence of MEF (20.67 ± 0.19 vs. 15.95 ± 0.21) (p= 0.001). The mESCs cultivated in the presence of MNPs showed morphology similar to ESCs, and its pluripotency was confirmed by expression of indifferentiation markers Oct-4 and Nanog by RT-PCR and high alkaline phosphatase activity. One bovine embryonic stem cell (bESCs) line was obtained and maintained by six subcultures for 60 days period. The pluripotency of the bESCs was confirmed morphologically as well as by Oct-4 e STAT-3 gene expression / As nanopartículas magnéticas (NPM) têm sido utilizadas em inúmeras aplicações biomédicas, destacando-se no tratamento do câncer, carreamento de drogas e diagnóstico por imagem de ressonância. As células tronco embrionárias (ES), devido à sua capacidade de auto-renovação e de diferenciação em vários tipos de células, oferecem um grande potencial para sua utilização na regeneração de tecidos e em tratamentos alternativos para muitas doenças degenerativas. Os objetivos do estudo foram: i) avaliar a citotoxicidade in vitro de NPM de maghemita funcionalizadas com ácido láurico, DMSA e citrato em células de melanoma humano (SK-MEL-37) através de ensaio de MTT, microscopia eletrônica e eletroforese de DNA em gel de agarose; ii) desenvolver um sistema de cultura utilizando as NPM previamente selecionadas e um magneto para expandir in vitro células tronco embrionárias murinas (mES) na ausência de co-cultura de fibroblastos embrionários murinos (MEF) (o estado indiferenciado das células mES foi analisado por citoquímica para fosfatase alcalina, por microscopia eletrônica e análise da expressão de genes Oct-4 e Nanog por RT-PCR); iii) isolar e expandir células ES a partir de blastocistos bovinos, e caracterizar a sua pluripotência por meio da análise da expressão dos genes Oct-4 e STAT-3 por RT-PCR. As NPM revestidas com ácido láurico, citrato e DMSA não apresentaram citotoxicidade, a julgar pelos altos valores de IC50 encontrados (254, 433 e 2260 μg de ferro/mL, respectivamente), sendo que as nanoparticulas revestidas com citrato foram as escolhidas para serem utilizadas como suporte para expandir as células mES. O tempo de duplicação para as células cultivadas na presença da NPM foi ligeiramente maior do que na presença com co-cultura de MEF (20,67 ± 0,19 vs. 15,95 ± 0,21) (p= 0,001). A morfologia das células mES cultivadas na presença da NPM foi semelhante à de células ES, sendo que, a sua pluripotência foi confirmada pela expressão dos marcadores de indiferenciação Oct-4 e Nanog por RT-PCR e da alta atividade de fosfatase alcalina. Uma linhagem de células tronco embrionárias bovinas (bES) foi obtida e mantida por seis subcultivos por período de 60 dias. A pluripotência das células bES foi confirmada morfologicamente, bem como pela expressão dos genes do estado indiferenciado Oct-4 e STAT-3

Made available in DSpace on 2014-07-29T15:12:48Z (GMT). No. of bitstreams: 1 Dissertacao - Joel Rocha da Silva.pdf: 557734 bytes, checksum: 97955f40a90305a3592aea224371f9ea (MD5) Previous issue date: 2008-05-27 / Magnetite nanoparticles were prepared by the coprecipitation of ions Fe2+ and Fe3+ using ammonia solution as precipitating agent. Maghemite nanoparticles were prepared by forced oxidation of magnetite nanoparticles in acidic medium using nitrate ions as oxidizing agent. The magnetic nanoparticles were used to the preparation of aqueous magnetic fluids samples by the functionalization of the nanoparticles with bilayers of laurate/laurate and laurate/Pluronic. Aliquots of the magnetic fluids were dried and the resultant powders were characterized by chemical analysis (the contents of ions Fe2+ and Fe3+), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The contents of ions Fe2+ and Fe3+ in all the samples showed that the nanoparticles are not pure magnetite or maghemite phases. X-ray powder diffraction (XRD) indicated the existence of inverse cubic spinel phase, but didn't permit the distinction between magnetite and maghemite phases. Based on the results of chemical and XRD analyses, the nanoparticles could be better characterized as reduced maghemite, which mean maghemite phase containing ions Fe2+. The average sizes of the oxide nanoparticles estimated by XRD were around of 10 nm. FTIR analyses showed that the nanoparticles were functionalized with bilayers of laurate/laurate and laurate/Pluronic. FTIR analyses also were indicative of the maghemite phase. The hydrodynamic size of the functionalized nanoparticles measured by PCS were in the range of 70-90 nm for the samples based on laurate and in the range of 100-200 nm for the samples containing Pluronic. The measurements of zeta potential showed that the magnetic fluids based on laurate bilayers presented better colloidal stability than that one based on bilayers of laurate/Pluronic. On the other hand, the studies of colloidal stability in cell culture medium by hydrodynamic size measurements showed the lost of colloidal stability of all the samples, in all the concentrations of medium investigated. The fluids with laurate/laurate bilayers showed higher ratio of aggregation in the culture medium than the fluids with laurate/Pluronic. The association of amphotericin B with nanoparticles was carried out only using the samples with laurate bilayers. The results showed that the ratio of association depends on the concentration of amphotericin added to the magnetic fluid. It was observed 100% of amphotericin association in the range of nanoparticles/amphotericin concentrations used, which in turn are adequated for posterior in vivo studies / Nanopartículas de magnetita foram preparadas pela coprecipitação dos íons Fe2+ e Fe3+ usando uma solução de amônia como o agente de precipitação. As nanopartículas de maguemita foram preparadas por oxidação forçada de nanopartículas de magnetita usando íons nitrato como o agente de oxidação, em meio ácido. As nanopartículas magnéticas foram usadas para a preparação de fluidos magnéticos aquosos pela funcionalização das nanopartículas com bicamadas de laurato/laurato e laurato/Pluronic. As alíquotas dos fluidos magnéticos foram secas e o pó resultante foi caracterizado por análise química (teores dos íons Fe2+ e Fe3+), difração de raios X pelo método do pó (DRX) e espectroscopia na região do infravermelho com transformada de Fourier (FT-IR). Os teores dos íons Fe2+ e Fe3+ em todas as amostras mostram que as nanopartículas não são fases puras da magnetita ou de maguemita. A difração de raios X (DRX) pelo método do pó indicou a existência da fase cúbica de espinélio inverso, mas não permite a distinção entre a magnetita e as fases de maguemita. Baseado nos resultados de análises químicas e de DRX, as nanopartículas poderiam ser melhor caracterizadas como maguemita reduzida, a qual resulta em uma fase de maguemita contento íons Fe2+. Os tamanhos médios das nanopartículas dos óxidos estimados por DRX foram em torno de 10 nm. As analises de FT-IR mostram que as nanopartículas foram funcionalizadas com bicamadas de laurato/laurato e laurato/Pluronic. As análises de FT-IR também foram indicativos da fase maguemita. O tamanho hidrodinâmico das nanopartículas funcionalizadas medidas por PCS foi em torno de 70-90 nm para amostras a base de laurato e em torno de 100-200 nm para amostras contendo Pluronic. As medidas de potencial zeta mostraram que os fluidos magnéticos a base de bicamada de laurato apresentam melhor estabilidade coloidal do que os a base de bicamada de laurato/Pluronic. Por outro lado, o estudo da estabilidade coloidal em meio de cultura por medidas de tamanho hidrodinâmico mostra a perda da estabilidade coloidal de todas as amostras, em todas as concentrações do meio investigado. Os fluidos com bicamadas de laurato/laurato mostraram taxas mais altas de agregação no meio de cultura do que os fluidos com laurato/Pluronic. Os estudos de associação de anfotericina B com nanopartículas foram realizados somente usando as amostras com bicamadas laurato/laurato. Os resultados mostraram que a taxa de associação depende da concentração de anfotericina adicionada ao fluido magnético. Foi observado 100% de associação da anfotericina na faixa da concentração nanopartículas/anfotericina usadas, que por sua vez são adequadas para posteriores estudos in vivo

Les thérapies ciblées constituent une révolution médicale dans le traitement du cancer. Dans ce contexte, le pseudopeptide multivalent N6L, qui cible spécifiquement les cellules tumorales et induit leur mort, apparaît comme une molécule prometteuse. Le N6L cible en effet deux nucléoprotéines surexprimées à la surface des cellules cancéreuses qui sont la nucléoline et la nucléophosmine. L'étude du mécanisme d'action anti-métastatique du N6L, dans lequel l'implication du TIMP-3 a été soulignée, a permis d'identifier une nouvelle cible : les glycosaminoglycanes sulfatés (GAG).Dans le but de développer une approche multimodale pour le diagnostic et le traitement du cancer du sein, le N6L a été greffé à la surface de nanoparticules magnétiques (NPM-N6L). La propriété de ciblage tumorale des NPM-N6L a été démontrée in vitro et in vivo. Leur cible tumorale majeure fut les GAG.Par ailleurs, l'activité anti-tumorale du N6L dans le traitement du cancer de la prostate à différents stades de la maladie a été démontrée in vitro et in vivo. La cible tumorale mise en jeu fut la nucléophosmine. En outre, ce potentiel anti-tumoral implique une diminution de l'activité du récepteur aux androgènes et probablement une voie de signalisation impliquant une interaction entre la nucléophosmine phosphorylée et le récepteur aux androgènes. / Targeted therapies constitute a revolution in the medical treatment of cancer. In this context, the multivalent pseudopeptide N6L that specifically target tumor cells and induces their death seems a promising molecule. The N6L targets two nucleoproteins that are overexpressed on the surface of cancer cells: nucleolin and nucleophosmin. The study of the N6L anti-metastatic mechanism of action in which TIMP-3 was involved, has identified a new target: sulfated glycosaminoglycans (GAG).In order to develop a multimodal approach for diagnosis and treatment of breast cancer, the N6L was grafted to the surface of magnetic nanoparticles (MNP-N6L). Tumor targeting properties of MNP-N6L was demonstrated in vitro and in vivo. Their major tumor target was GAG.Furthermore, the N6L anti-tumor activity in the treatment of prostate cancer at different stages of the disease was demonstrated in vitro and in vivo. The target involved in this activity was nucleophosmin. Furthermore, this anti-tumor potential implies a decrease in the activity of the androgen receptor and probably a signaling pathway involving an interaction between phosphorylated nucleophosmin and the androgen receptor.

Les nanocolloïdes magnétiques sont des dispersions de nanostructures magnétiques dans un liquide porteur. Par la combinaison des propriétés du liquide et des particules magnétiques, ces dispersions peuvent être confinées, déplacées, déformées et contrôlées par l'application d'un champ magnétique externe et ont ainsi de nombreuses applications en nanosciences et les nanotechnologies. Nous avons étudié la dispersion de nanoparticules magnétiques (NPM) dans les solvants eutectiques profonds (DES). Ces solvants, constitués d'un mélange entre un sel d'ammonium (ici le chlorure de choline (Ch) et un donneur de liaison H (ici, l'ethyleneglycol (EG) ou l'urée (U)) ont des propriétés proches des liquides ioniques tout en étant biodégradables. L'un des verrous concernant ces dispersions est la nature des forces impliquées dans la stabilité colloïdale. En effet, on ne peut plus expliquer la stabilité des dispersions dans ces milieux par le modèle DLVO, classiquement utilisé dans l'eau, du fait de leur force ionique élevée. Nous avons dans en premier temps caractérisé soigneusement deux DES (ChEH (1:3) et ChU (1:2) en mol) du point de vue de la densité et viscosité pour des températures entre 20 et 45°C. Ceci nous a permis de montrer la forte association de ces liquides. Un protocole de dispersion de nanoparticules de maghémite (Fe2O3) ou de ferrite mixte (CoxZn1-xFe2O4) est ensuite proposé, et les dispersions sont étudiées par diffusion de rayonnement (lumière et SAXS). Il s'est avéré que les particules les plus petites étaient les mieux dispersées. Enfin, un test de synthèse de NPM dans des solutions d'argile a permis d'obtenir une polydispersité plus faible en sortie de synthèse. / Magnetic nanocolloids are dispersions of magnetic nanostructures in a carrier fluid. Thanks to the original properties of both the liquid and the magnetic particles, these dispersions can be confined, moved, deformed and controlled by applying an external magnetic field. Such dispersions thus have many applications in nanoscience and nanotechnologies.We studied the dispersion of magnetic nanoparticles in deep eutectic solvents (DES). These solvents (DES), obtained by mixing a quaternary ammonium salt (e.g., choline chloride Ch) and a hydrogen bond donor (e.g., ethyleneglycol EG or Urea U) have properties similar to ionic liquids, and are also biodegradable. One of the questions about these dispersions is the nature of the forces implied in colloidal stability, since the DLVO model classically used in water cannot be invoked here due to the very high ionic strength of the solvent.In a first step, we have carefully characterized two DES ((ChEG (1:3) and ChU (1:2) in mol), measuring the density and viscosity for temperatures between 20 and 45°C. We could thus show the high association in these liquids.A protocol to disperse nanoparticles of maghemite (Fe2O3) or mixed ferrite (CoxZn1-xFe2O4) is then proposed, and the obtained dispersions are studied by dynamic light scattering and SAXS. The size polydispersity was reduced by size sorting, and it reveals that the smallest particles are the most easy to disperse in the DES.Last, a synthesis of NMP in clay dispersion was tested and showed promising results with a reduced size polydispersity.

The optical response of several magnetic nanoparticle dispersions is studied by angle resolved transmittance at wavelength of 600 nm in zero-field and under an applied magnetic field of 0.1 T, with the purpose of exploring to what extent this could be used as a method of monitoring the colloidal dispersions. In an external magnetic field, magnetic particles will start to order into needle-like structures aligned with the field, which was observed by microscopy. This will change the light scattering caused by the particles. Results showed a clear effect from applying the magnetic field by a dip in the transmitted intensity at angles around 3-5 degrees. The scattering is compared to that of a homogeneous infinite cylinder and theoretical explanations to the effect are discussed. Spectrophotometry at wavelengths between 300-1100 nm is performed and compared with calculations from Kubelka-Munk approximation to give a first characterization of the particle dispersions. Particles used in this project are magnetite, Fe3O4, and maghemite, gamma-Fe2O3, nanoparticles with sizes ranging from 5-250 nm.

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The thesis has been focused on testing of micromethod of DNA isolation using magnetic particles from thermic-managed food products in a quality suitable for polymerase chain reaction (PCR). Currant jams were selected for the analysis. These were homogenized using plastic copist and stomacher in lysis buffer with cetyltrimethylammonium bromide (CTAB). The effect of chloroform-octanol and isopropanol in the preparation of homogenates was tested. Homogenates were used for DNA isolation by magnetic particles. Rough fraction of DNA was purified by binding on the magnetic particles after centrifugation of the CTAB complexes with proteins, polyphenols and polysaccharides. Two types of magnetic particles were tested: microparticles of poly(hydroxyethylmethacrylate-co-glycidylmethacrylate) - P(HEMA-co-GMA) and nanoparticles of iron oxides covered by poly(L-lysine) - PLL. Isolated DNA was analyzed spectrophotometrically - it was assessed its concentration and contamination by polyphenols and proteins. After that, amplification of the DNA was tested in PCR. Primers specific for plant ribosomal DNA were used. PCR products of expected length 700 bp were detected by agarose gel electrophoresis. It was shown that DNA isolated from currant jams using magnetic particles was in PCR-ready quality.