Made available in DSpace on 2014-07-29T15:07:08Z (GMT). No. of bitstreams: 1 Marcus Carriao dos Santos Dissertacao.pdf: 903168 bytes, checksum: 91f54bc8f60266322bb1f15c18b8d279 (MD5) Previous issue date: 2011-04-13 / In this work a magnetophoretic experiment (MPE) was developed to study the effect of a gradient of magnetic field in the diameter and size dispersivity of nanoparticles in a magnetic fluid (MF). In this experiment, the mass of a permanent magnet is measured by a balance which data varied due to the interaction with the magnetic fluid, which is placed a few centimeters above. Curves of variation of apparent mass of the magnet were obtained as function of time and related to the characteristics of fractions taken from the surface of the MF at different times. The MF consisted of magnetite nanoparticles surface-coated with phosphate. Samples were synthesized by the coprecipitation method and characterization was performed using x-ray diffraction, high resolution transmission electron microscopy (HR-TEM) and vibrating sample magnetometry (VSM). Fractions of the MF were taken during the MPE at five different times. Those fractions were characterized by VSM, from which magnetic diameters were estimated. The magnetic diameters showed a decrease of nanoparticle size in the surface of the MF sample submitted to MPE for longer times of exposure to the field gradient. These same fractions were characterized by HR-TEM and histograms of nanoparticles size distribution were made. Studies of mean and modal (obtained by lognormal fit) diameters had confirmed the behavior indicated by the magnetic diameters showing a decrease of size as function of time. Studies of standard deviation and full width at half maximum (obtained by lognormal fit) had shown a decrease in dispersivity. However, studies of the σ factor were inconclusive, since no significant variations were found for nanoparticles at the experimental size range. Indeed, the MPE results had shown a variation of 16.02% in modal diameter (Dmodal), 14.63% in mean diameter, 30.90% in standard deviation e 33.33% in full width at half maximum between the original sample and the part which was exposed to gradient magnetic field by 60 hours, of fluid with largest initial diameter (Dmodal = 9.24±0.08 nm and σ=0.238±0.009). In addition magnetohyperthemia experiments at 300 kHz were obtained for each sample. Higher specific absorption rates were found for larger particle sizes, which have important applications for cancer treatment. Therefore, we concluded that the magnetophoretic experiment can be used to select the magnetic fluids properties, due to diameter and size standard deviation control, for several technological, environmental and biomedical applications. / Neste trabalho foi desenvolvido um experimento magnetoforético (EMF) para estudar o efeito de um gradiente de campo magnético sobre o diâmetro e dispersão de tamanhos de nanopartículas em fluidos magnéticos (FM). Neste experimento, a massa de um imã permanente é medida por uma balança enquanto varia graças à interação com o FM, colocado alguns centímetros acima. Curvas de variação da massa aparente do imã foram obtidas em função do tempo e relacionadas às características de alíquotas retiradas da superfície do FM em tempos distintos. Os fluidos eram constituídos de nanopartículas de magnetita recobertas com fosfato. As amostras foram sintetizadas pelo método de coprecipitação e caracterizadas por difratometria de raios-x, microscopia eletrônica de transmissão de alta resolução (HR-TEM) e magnetometria de amostra vibrante (VSM). Foram retiradas alíquotas do EMF em cinco intervalos de tempo distintos. Essas alíquotas também foram caracterizadas por VSM e foram estimados diâmetros magnéticos a partir delas. Os diâmetros magnéticos mostraram uma diminuição do tamanho das nanopartículas na superfície da amostra submetida ao EMF para tempos maiores de exposição ao gradiente de campo. Essas mesmas alíquotas foram ainda caracterizadas por HR-TEM e foram construídos histogramas com os tamanhos das nanopartículas. Estudos dos diâmetros médios e modais (obtido pelo ajuste lognormal) confirmaram o comportamento estimado pelos diâmetros magnéticos e mostraram a diminuição do tamanho das nanopartículas em função do tempo. O estudo dos desvios padrão e da largura a meia altura (obtido pelo ajuste lognormal) indicaram uma diminuição da dispersão. O estudo do fator σ (parâmetro do ajuste lognormal) foi inconclusivo, não apresentando variações significativas na faixa de tamanhos estudada. Os resultados mostraram que o EMF produziu uma variação de 16,02% no diâmetro modal (Dmodal), 14,63% no diâmetro médio, 30,90% no desvio padrão e 33,33% na largura a meia altura entre a amostra original e a alíquota exposta ao gradiente de campo por 60 horas, para o fluido de maior diâmetro inicial (Dmodal = 9,24±0,08 nm e σ=0,238±0,009). Estudos de magnetohipertermia foram realizados a 300kHz para as alíquotas estudadas. Foram encontradas taxa de absorção específicas (SAR) maiores para sistemas com nanopartículas maiores, propriedade muito importante nas aplicações relacionadas ao tratamento de câncer. Portanto, conclui-se que o experimento magnetoforético pode ser utilizado para selecionar propriedades de fluidos magnéticos, por meio do controle do diâmetro e desvio padrão de tamanhos, para diversas aplicações tecnológicas, ambientais e biomédicas.

Made available in DSpace on 2014-07-29T15:07:10Z (GMT). No. of bitstreams: 1 Laylla Silva Ramalho.pdf: 1874808 bytes, checksum: 1da12c8c62ee1a2f9ad9bb50e4e4890b (MD5) Previous issue date: 2012-05-11 / Magnetic fluids consist of surface-coated magnetic nanoparticles dispersed in a liquid carrier. These nanostructures have attracted a lot of attention of the biomedical community because of its possible applications as drug carriers, disease detection, and also on the treatment of several diseases, including cardiovascular ones. This work had the following objectives: (i) evaluate the effect ex-vivo of biocompatible magnetic nanoparticles in the rat heart function and, in-vivo, in the arterial blood pressure and heart rate of the rats, as well as, (ii) investigate the endocytosis and exocytosis of the nanoparticles through a magnetophoresis technique. The samples were characterized by X-ray diffraction (XRD), Dynamic light sacttering (DLS) and Vibrating sample magnetometer (VSM). The cardiac function was evaluated by the Langendorf technique under constant flow. On the other hand, in order to evaluate the effect of nanoparticles in the cardiovascular parameters, femoral artery and vein were cannulated and arterial pressure and heart rate were measure after 24 hs. The magnetic fluid infusion in the isolated heart showed a tiny increase of the intraventricular diastólic pressure and a decrease of the intraventricular systolic pressure. No changes were observed in perfusion pressure. The infusion of the magnetic nanoparticles in the rats had not promoted any significant variations of the artery pressure or the heart rate. These results suggest that magnetic nanoparticles can be used on clinical trials. In addition, magnetophoresis experiments were preformed in order to investigate phenomenon associated to nanoparticles and dissociated cardiomyocytes interactions from rat heart. Different samples containing distinct particle sizes and coating layers were evaluated as function of incubation time. It was observed that, besides endocytosis (or adsorption), an exocytosis (or desorption) mechanism start to occur above a critical time. A mathematical model that takes into account both mechanisms were developed which, together with other works from the literature, allowed us to estimate the individual wrapping time of the nanoparticles. The results show a strong dependence upon nanoparticle diameter and corroborate with theoretical models of receptor-mediated endocytosis of nanoparticles. / Fluidos magnéticos (FM) consistem de nanopartículas magnéticas formadas por ferritas dispersas em um líquido carreador formando uma composição coloidal. Estas nanoestruturas têm atraído a atenção da comunidade biomédica já que possuem aplicações na área de carreadores de fármacos, detecção de doenças, e podem, ainda, contribuir para o tratamento de diversas doenças, inclusive cardiovasculares. Este trabalho teve como objetivos: (i) avaliar o efeito ex-vivo de nanopartículas magnéticas biocompatíveis no funcionamento de corações de ratos e, in-vivo, na pressão arterial e freqüência cardíaca de ratos wistar e, também, (ii) investigar o processo de endocitose/adsorção e exocitose/dessorção de nanopartículas magnéticas biocompatíveis em cardiomiócitos via técnica de magnetoforese. As amostras foram sintetizadas e caracterizadas por Difração de Raio-X (DRX), Espalhamento de Luz Dinâmico (DLS) e Magnetometria de Amostra Vibrante (VSM). A função cardíaca foi avaliada pela técnica de Langendorff com fluxo constante. Por outro lado, para avaliar o efeito das nanopartículas nos parâmetros cardiovasculares in vivo, artéria e veia femoral foram canuladas e o registro da pressão arterial e frequência cardíaca foi realizado após 24 hs. A infusão do fluido magnético nos corações isolados promoveu ligeiro aumento na pressão intraventricular diastólica e uma queda na pressão intraventricular sistólica. O fluido promoveu uma leve diminuição na pressão de perfusão, o que representa uma vasodilatação coronariana, sendo esse efeito reversível durante a lavagem. A infusão das nanopartículas magnéticas não promoveu alterações significativas na pressão arterial ou frequência cardíaca. Estes resultados sugerem a viabilidade para a utilização clínica das nanopartículas magnéticas. Adicionalmente, experimentos de magnetoforese foram realizados para avaliar fenômenos associados à interação de nanopartículas com cardiomiócitos dissociados do coração de ratos. Diferentes amostras de nanopartículas de ferrita de manganês, contendo diâmetros distintos e diferentes camadas de cobertura, foram avaliadas em função do tempo de incubação. Observou-se, além de um processo endocitótico (ou adsortivo), um mecanismo exocitótico (ou dessortivo) a partir de um tempo crítico. Um modelo matemático que incluiu ambos os mecanismos foi desenvolvido e, conjuntamente com outros da literatura, permitiu estimar o tempo de wrapping de cada nanopartícula. Os resultados mostraram-se fortemente dependente do diâmetro das nanopartículas e, inclusive, corroboram com modelos teóricos de endocitose de nanopartículas mediada por receptores.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-03T15:17:06Z No. of bitstreams: 2 Dissertação - Breiner Gabriel Canedo Silva - 2016.pdf: 5933676 bytes, checksum: f71deace1dcdc99b7cbc79191cf1374d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-03T15:18:38Z (GMT) No. of bitstreams: 2 Dissertação - Breiner Gabriel Canedo Silva - 2016.pdf: 5933676 bytes, checksum: f71deace1dcdc99b7cbc79191cf1374d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-08-03T15:18:38Z (GMT). No. of bitstreams: 2 Dissertação - Breiner Gabriel Canedo Silva - 2016.pdf: 5933676 bytes, checksum: f71deace1dcdc99b7cbc79191cf1374d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-07-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work magnetic nanoparticles composed of maghemite coated with L-lysine or DL-Histidine (crystallite average diameter between 4.5 to 8.1 nm.) were synthesized via the Fe (II) and Fe (III) coprecipitation method. The synthesized solids were dispersed in water to obtain aqueous suspensions called magnetic fluids. The samples were characterized by X-ray diffraction, infrared spectroscopy, thermogravimetry, UV-Vis spectrophotometry, transmission electron microscopy, electrophoretic and dynamic light scattering. The suspended colloidal nanoparticles showed positive zeta potential at physiological pH, which enables the adsorption of negatively charged molecules of chromosomal and plasmid DNA on their surfaces. Their hydrodynamic radius were smaller than those reported in the literature (100nm) allowing phagocytosis of the nanostructure. A maghemite/L-Lysine sample was selected for DNA adsorption (chromosomal DNA of Humicola grisea fungus and shRNA and GFP encoding plasmids) and subsequent coating with dextran, for protection of its genetic information. Plasmids and dextran adsorption was evidenced by the increasing of the hydrodynamic radius of the samples, and the presence of DNA and dextran related bands in the infrared. / Neste trabalho, foram sintetizadas nanopartículas magnéticas constituídas de maghemita funcionalizada com L-Lisina ou DL-Histidina (cristalitos com diâmetro médio de 4,5 a 8,1 nm), pelo método da coprecipitação dos íons Fe (II) e (III). Os sólidos obtidos foram dispersos em água para obtenção de suspensões aquosas denominadas fluidos magnéticos. As amostras obtidas foram caracterizadas pelas técnicas de difração de raios X, espectroscopia de infravermelho, termogravimetria, espectrofotometria UV-Vis, microscopia eletrônica de transmissão e espalhamento de luz dinâmico e eletroforético. As nanopartículas em suspensão apresentaram potencial zeta positivo em pH fisiológico, possibilitando assim adsorção de moléculas de DNA (cromossômico e plasmidial) negativamente carregadas, além de um raio hidrodinâmico inferior ao relatado na literatura (100 nm) para que ocorra a fagocitose das nanoestruturas. Uma amostra maghemita/L-Lisina foi selecionada para adsorção de DNA (cromossômico de fungo Humícola grísea e de plasmídeos codificadores de shRNA e GFP) e posterior recobrimento com dextrana, para proteção de sua informação genética. A adsorção dos plasmídeos e da dextrana foi evidenciada pelo aumento do raio hidrodinâmico das amostras e pela presença das bandas relativas à dextrana e ao DNA nos espectros de infravermelho.

Submitted by Franciele Moreira (francielemoreyra@gmail.com) on 2017-09-11T13:58:47Z No. of bitstreams: 2 Dissertação - Marcus Vinícius Araújo - 2017.pdf: 21442655 bytes, checksum: 3698012eda944b8f418aebe11accbd00 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-09-15T15:45:28Z (GMT) No. of bitstreams: 2 Dissertação - Marcus Vinícius Araújo - 2017.pdf: 21442655 bytes, checksum: 3698012eda944b8f418aebe11accbd00 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-09-15T15:45:28Z (GMT). No. of bitstreams: 2 Dissertação - Marcus Vinícius Araújo - 2017.pdf: 21442655 bytes, checksum: 3698012eda944b8f418aebe11accbd00 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-07-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Nanoparticles based on Mn-ferrite, Mn1−xAxFe2O4, doped with copper, magnesium and cobalt (A = Cu, Mg ou Co) were synthesized by hydrothermal method under pressure, with X varying from 0 to 0, 5. Magnetic fluids stable in physiological conditions were obtained surface-coating the nanoparticle with citric acid. X-ray diffraction confirmed the spinel structure. Energy dispersive spectroscopy (EDS) confirmed the success of the synthesis of the mixed ferrite, where the element composition agreed with the value expected within an error of 10%. Transmission electron microscopy showed sphericalshaped nanoparticles, while magnetization data at room temperature allowed the analysis of the coercivity field (Hc) and the saturation magnetization (Ms). Ms decreased with the increase of X for the Cu and Mg doped samples, while the opposite effect was observed for Co doped nanoparticles. Hc increased the higher the X value for all the samples. The effect on the Cu and Mg-doped ferrites are explained by the increase in particle size. However, the Co-doped samples, showed a diameter increasing the higher X, but Hc also increased. In this case the Hc behavior is explained by the increase concentration of Co and its effect on the magnetic anisotropy which increases for higher Co content. The magnetic hyperthermia efficiency of the magnetic fluids, for all samples, were investigated in a field amplitude ranging from 50 Oe to 170 Oe and frequencies from 110 kHz up to 990 kHz. The hyperthermia efficiency decreased with X increasing, considering the case of 130Oe and 333 kHz, which indicates that at this experimental condition undoped Mnferrite nanoparticles are better for hyperthermia. In most of the samples it was observed that the efficiency scaled with the square of the field amplitude, which is in accordance with Linear Response Theory (LRT). In addition, the hyperthermia frequency dependence study showed a saturation effect, for some samples, at a frequency higher than 600 kHz. The experimental data as function of frequency were susccessfully curve fitted with the LRT model using 2 free parameters related to the effective relaxation time ( ef ) and the equilibrium susceptibility ( 0). In particular, for theMn-ferrite sample for a field of 130Oe it is found ef = 5, 2 · 10−7s and 0 = 0, 028. The value of ef can be explained using an effective magnetic anisotropy value of 2·105 erg/cm3. The value is one order of magnitude higher than the bulk value, and allowed one to estimate the surface anisotropy contribution to in the order of 0, 04 erg/cm2. On the other hand, a linear chain formation model, for this sample consisted of a trimer (3 nanoparticles), can also explain the increase of the effective anisotropy. Moreover, we found a 0 value lower than the estimated Langevin susceptibility. In order to explain this, a new model, valid in the linear regime, was developed considering the contribution from blocked nanoparticles. Indeed, the analysis of hyperthermia data using this model indicates that the contribution to heat generation spans from 34.7% of the nanoparticles for a field of 110 Oe up to 52.5% at 170 Oe. / Nanopartículas à base de ferrita de Mn, Mn1−xAxFe2O4, dopadas com cobre, magnésio ou cobalto (A = Cu, Mg ou Co) foram sintetizadas pelo método hidrotermal sob pressão, com X variando de 0 até 0, 5. Posteriormente, fluidos magnéticos estáveis em pH fisiológico foram obtidos recobrindo a superfície das nanopartículas com ácidocítrico. A caracterização estrutural por raios-X confirmou a fase cristalina do tipo espinélio. A técnica de espectroscopia de energia dispersiva confirmou o sucesso da síntese de ferrita mista, quanto a sua composição, com um erro de até 10%. Microscopia eletrônica de transmissão revelou formação de nanopartículas esféricas, enquanto medidas de magnetização a temperatura ambiente permitiram uma análise do campo coercitivo (Hc) e da magnetização de saturação (Ms). Ms caiu com aumento de X para amostras dopadas com Cu e Mg, enquanto o oposto foi observado para Co. O Hc cresceu com o aumento de X para todas as amostras. Para as amostras dopadas com Cu e Mg tal efeito é explicado pelo aumento do diâmetro das nanopartículas. No caso das amostras dopadas com Co, o diâmetro caiu com X crescendo, mas Hc aumentou. Neste caso o comportamento do Hc é explicado pela maior contribuição a anisotropia magnética aumentando a proporção de Co na ferrita. A eficiência da hipertermia magnética (EHM) dos fluidos magnéticos, de todas as amostras, foi avaliada numa faixa de amplitude de campo de 50 Oe à 170 Oe para frequências variando entre 110 kHz à 990 kHz. A EHM caiu com X aumentando para H0 = 130 Oe e f = 333 kHz, o que indica, nesta condição experimental, que a ferrita de Mn é a amostra mais eficiente para hipertermia. A maior parte das amostras apresentou um EHM escalando com o quadrado da amplitude de campo magnético, em concordância com o esperado pela Teoria do Regime Linear (TRL). O estudo da EHM em função da frequência (f) revelou que algumas amostras apresentam saturação para f > 600 kHz. Os dados experimentais de hipertermia em função da frequência foram ajustados com sucesso, para todas as amostras, usando apenas 2 parâmetros livres relacionados ao tempo de relaxação efetivo ( ef ) e a susceptibilidade de equilíbrio ( 0). Em particular, para a amostra de ferrita de Mn e H0 = 130 Oe encontramos ef = 5, 2 · 10−7 s e 0 = 0, 028. O valor obtido para ef pode ser explicado para uma anisotropia magnética efetiva com 2 · 105 erg/cm3. Este valor é uma ordem de grandeza maior que o do bulk, e permite estimar uma anisotropia de superfície da ordem de 0, 037 erg/cm2. Por outro lado, a formação de cadeias lineares, contendo 3 partículas, também é capaz de explicar o aumento da anisotropia. O valor encontrado para 0 é menor que aquele estimado para a susceptibilidade de Langevin. Para explicar tal resultado, um novo modelo, válido no regime linear, foi desenvolvido considerando a contribuição de partículas bloqueadas. Neste caso, foi possível estimar, pela análise da EHM em função da frequência, que a fração de partículas contribuindo para a geração de calor sobe de 34, 7% em H0 = 110 Oe para 52, 5% em 170 Oe.

Orientador: Marcelo Knobel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin. / Made available in DSpace on 2018-08-12T12:15:41Z (GMT). No. of bitstreams: 1 LeonVanegas_AlvaroAugusto_M.pdf: 1938062 bytes, checksum: c09af0b2555e73ce9f9d903c4094424c (MD5) Previous issue date: 2008 / Resumo: Neste trabalho estudamos o comportamento magnético de uma amostra de nanopartículas de níquel com alto grau de desordem estrutural com uma distribuição estreita de diâmetros. Encontramos que o sistema apresenta duas fases magnéticas, uma paramagnética, que segue uma lei tipo Curie-Weiss com constante de Curie C = 3, 36 × 10-3emuK/gOe e temperatura crítica de TC = 8, 5 K e outra ferromagnética que não segue o comportamento superparamagnético clássico a altas temperaturas e provavelmente é originada pela formação de pequenos clusters que são os responsáveis pela irreversibilidade observada por baixo dos 23 K nos dados de magnetização FC-ZFC a 50 Oe. Os dados obtidos de Magnetização FC mostram um aumento abrupto da magnetização em 23 K relacionada com o crescimento e criação de novos clusters e estes, devido a interações de tipo dipolar e de troca e a uma forte anisotropia superficial, geram estados frustrados tipo vidro de spin que se refletem na queda na magnetização em 17 K. Em 7 K os restantes spins superficiais que não haviam se incorporado aos clusters ferromagnéticos da partícula tentam-se ordenar. Os dados dos ciclos de histereses confirmam a forte anisotropia superficial e a presença de uma grande porcentagem de spins não ordenados na superfície. / Abstract: We have studied the magnetic behavior of amorphous nickel nanoparticles sample with size narrow distributions. We find that the system have two magnetic phases, one paramagnetic, that follows the Curie-Weiss law with C = 3.36×10-3emuK/gOe and TC= 8.5 K and other ferromagnetic that not follows the classic superparamagnetic behavior to high temperatures and is probably result of small clusters formation, who are the responsibles of observed irreversibility in the Field Cooled magnetization data with magnetic field of 50 Oe. The obtained data of MFC shows a strong increase in the magnetization in 23 K related with the growth and the appearance of new clusters, and these, due to dipolar and exchange interactions and strong surface anisotropy, generates frustrate spin-glass-like states that lead up to a decrease in magnetization at 17 K . At 7 K the system begins to order the remaining superficial spins that are outside the ferromagnetic part of the particle. The histeresis data confirm a strong surface anisotropy and a considerable part of no ordered spins on the surface. / Mestrado / Materiais Magneticos e Propriedades Magneticas / Mestre em Física

Multifunctional nanocomposites are promising for a variety of applications ranging from microwave devices to biomedicine. High demand exists for magnetically tunable nanocomposite materials. My thesis focuses on synthesis and characterization of novel nanomaterials such as polymer nanocomposites (PNCs) and multi-walled carbon nanotubes (MWCNTs) with magnetic nanoparticle (NP) fillers. Magnetite (Fe3O4) and cobalt ferrite (CoFe2O4) NPs with controlled shape, size, and crystallinity were successfully synthesized and used as PNC fillers in a commercial polymer provided by the Rogers Corporation and poly(vinylidene fluoride). Magnetic and microwave experiments were conducted under frequencies of 1-6 GHz in the presence of transverse external magnetic fields of up to 4.5 kOe. Experiments confirm strong magnetic field dependence across all samples. When incorporated in to a cavity resonator device, tangent losses were reduced, quality factor increased by 5.6 times, and tunability of the resonance frequency was demonstrated, regardless of NP-loading. Work on PNC materials revealed the importance of NP interactions in confined spaces and motivated the study of confinement effects of magnetic NPs in more controlled environments, such as MWCNTs with varying diameters. MWCNTs were synthesized with diameters of 60 nm, 100 nm, 250 nm, and 450 nm to contain magnetic NP fillers (~10 nm) consisting of ferrites of the form MFe2O4, where M = Co2+, Ni2+, or Fe2+. All confined samples exhibit superparamagnetic-like behavior with stronger magnetic response with respect to increasing MWCNT diameter up to 250 nm due to the enhancement of interparticle interactions. This thesis provides the first systematic study of this class of nanocomposites, which paves the way to inclusion of novel nanostructured materials in real-world applications.

Le développement des nanotechnologies a permis à la médecine de progresser là où lesméthodes traditionnelles de diagnostic et de thérapie connaissaient certaines limites. La manipulationet le contrôle de l’infiniment petit permet aujourd’hui de créer des systèmes adaptés à l’environnementcellulaire.Dans ce travail, nous nous sommes intéressés au potentiel des nanoparticules magnétiques d’oxydede fer en nanomédecine et notamment à l’utilisation de leurs propriétés magnétiques particulièrespour la mise au point de nouveaux matériaux pour la délivrance de principe actif par activationthermomagnétique. Notre système est constitué d’un hydrogel physique biocompatible, denanoparticules magnétiques et d’émulsions de mésophases lipidiques (Isasomes). Les Isasomes sontdes dispersions de systèmes auto assemblés qui selon la température peuvent changer de structure(phases hexagonales, cubiques,…). L’ajout d’un principe actif aux Isasomes peut aussi modifier leurstructure interne ; des mesures de SAXS ont permis de confirmer cet effet. Ces émulsionsnanostructurées ont servi de réservoir aux molécules modèles de principe actif (le radical TEMPO).Après activation magnétique, la diffusion contrôlée du principe actif hors de l’hydrogel a été suivie parRPE. Enfin, les nanoparticules ont été fonctionnalisées de façon à concevoir un hydrogel réticulé parles nanoparticules magnétiques. Les diverses étapes de la fonctionnalisation ont été validées pardifférentes techniques expérimentales (Diffraction de rayons X, MET, Raman, IRTF, Zétamétrie, ATG,XPS). / The development of nanotechnology led to significant progress in medicine especially wheretraditional methods of diagnosis and therapy showed limits. The manipulation and control of thephysics at the nanoscale offered new opportunities for creating systems tailored to the cellularenvironment. In this work, we were interested in the high potential of magnetic nanoparticles of ironoxide in medicine. In particular, we would like to use their peculiar magnetic properties for developingnew materials for the delivery of active compounds through thermomagnetic activation. Our systemconsists of a biocompatible hydrogel with confined magnetic nanoparticles and lipid-based emulsions,called Isasomes. Those are dispersions of lipid mesophases (hexagonal, cubic,…) that can be tunedby temperature or composition. The incorporation of an active compound into the Isasomes canequally modify their internal structure as confirmed by SAXS measurements. These nanostructuredemulsions are used here as reservoirs for model molecules (radical TEMPO), which are trapped intothe hydrogel. After magnetic activation, the controlled release of TEMPO outside the hydrogel hasbeen followed by Electron Paramagnetic Resonance (EPR). Finally, magnetic nanoparticles havebeen functionalized and connected to hyaluronic acid in order to design a crosslinked hydrogel. Thevarious steps of functionalization have been checked by various experimental techniques (Xrays,Raman spectroscopy, TEM, FTIR, zetametry, TGA, XPS).

Orientador: Marcelo Knobel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-30T18:13:51Z (GMT). No. of bitstreams: 1 OrozcoHenao_JuanManuel_M.pdf: 7687296 bytes, checksum: d9aecf2d118aed0c43ab747d0dcff34c (MD5) Previous issue date: 2016 / Resumo: Nanopartículas de magnetita com diâmetros entre 5nm e 19nm sintetizadas mediante um método de decomposição térmica são apresentadas. A caracterização estrutural é feita usando diferentes técnicas experimentais como a microscopia eletrônica de transmissão (TEM), difração de raios-X e espalhamento de raios-X a baixos ângulos (SAXS) de onde são obtidos os tamanhos e a forma das nanopartículas. As propriedades magnéticas e de magneto-hipertermia das nanopartículas são estudadas para diferentes parâmetros de produção como concentração dos surfactantes, temperaturas de refluxo e atmostfera de crescimento. A dependência com a temperatura das propriedades magnéticas são analisadas dentro do marco do modelo usual do superparamagnetismo e o modelo de interação superparamagnética (ISP), de onde os parâmetros magnéticos dependentes do tamanho como anisotropia magnética (1.06x10^4 J/m^3 até 9.91x10^4 J/m^3), momento magnético por partícula (2618?B até 11500?B), temperatura de bloqueio (18K até mais de 300K) e energia de ineração dipolar magnética (0.55x10^-21 J até 5.5x10^-21 J) são inferidos. Os resultados de magneto-hipertermia foram obtidos mediante a medição da resposta térmica das nanopartículas de magnetita suspendidas em tolueno. Valores da taxa de absorção específica (SAR) são calculados experimental e teoricamente utilizando a teoria de resposta linear para um sistema superparamagnético não interagente. Valores de SAR entre 3.0W/g e 40.3W/g e a sua dependência com a frequência e o campo aplicado são apresentados. Como resultado interessante, a resposta de magneto-hipertermia para as nanopartículas de 19nm preparadas na presença de oxigênio e mais de 10 vezes maior do que nanopartículas similares mas obtidas na ausência da atmosfera de oxigênio. Também é destacada a possibilidade de prever a resposta de magneto-hipertermia num sistema de nanopartículas magnéticas mediante a obtenção dos parâmetros de caracterização magnetica e estrutural / Abstract: Magnetite nanoparticles with diameters between 5nm and 19nm synthesized by means of a thermal decomposition method are presented. Structural characterization is made by different experimental techniques such as transmission electron microscopy (TEM), X-ray diffraction and Small Angle X-ray Scattering (SAXS) from where nanoparticles size and shape are obtained. Magnetic and magneto-hyperthermia properties of the nanoparticles are studied for different production parameters, such as surfactant concentrations, refluxing temperature and growth atmosphere. Temperature dependence of the magnetic properties are analyzed in the framework of the standard superparamagnetism model and the interacting superparamagnetic model (ISP), from where size dependent magnetic parameters for each sample such as anisotropy (1.06×10^4 J/m^3 to 9.91x10^4 J/m^3) magnetic moment per particle (2618?B to 11500?B), blocking temperature (18K to above 300K) and magnetic dipolar interaction energy on dried nanoparticle samples (0.55 × 10^?21 J to 5.5 × 10^?21 J) are inferred. Magneto-hyperthermia results are obtained by measuring the thermal response of magnetite nanoparticles dissolved in toluene. Specific absorption rate (SAR) values are theoretically and experimentally calculated by means of a linear response theory approach of a non-interacting superparamagnetic system. SAR values between 5.8W/g and 40.3W/g are reported; interestingly, the magneto-hyperthermia response for 19nm nanoparticles prepared in presence of an oxygen atmosphere is more than 10 times larger than similar particles obtained in absence of oxygen atmosphere. Also it is important to highlight the possibility to obtain the magneto-hyperthermia behavior of a magnetic nanoparticles system by knowing a priori its structural and magnetic characterization parameters / Mestrado / Física / Mestre em Física / 1247647/2013 / CAPES

Reversible adsorption of nucleid acids on magnetic carriers was studied in this diploma thesis. Magnetic P(HEMA-co­-GMA) microspheres and magnetic glass particles were used. The aim of the study was to isolate DNA in suitable quality for polymerase chain reaction (PCR). Adsorption of DNA on magnetic carriers was achieved after DNA condensation by PEG and NaCl in separation mixture. PEGs of various molecular weight (600 and 6000 g/mol) and different concentrations of PEG in separation mixture (4, 8, 12, 16%) were used. Quantity of eluted DNA incerased with molecular weight and concentration of PEG in separation mixtures. Optimized experimental conditions were applied for the separation of DNA from chicken erythrocytes, purified DNA, DNA in crude lysates of bacterial cells of Lactobacillus paracasei ssp. paracasei CCDM 211/06 and from real samples (liquid dairy products, hard cheese). The presence of target DNA in eluates was tested using genus specific PCR (genus Lactobacillus) or species specific PCR (species Bifidobacterium longum) Aqueous two-phase system (liquid-liquid) was used for separation of DNA from real symplex, too. At first the condiotions aqueous two-phase systém creation were studied. It was created by 16% PEG of various molecular weight (600, 6000 g/mol) and by various concentration of ammonium sulphate. Reversible DNA adsorption on carboxyl group-containing magnetic nonporous P(HEMA-co-EDMA) microspheres for the isolation PCR-ready DNA from liquid dairy products containing PCR inhibitors was studied, too. The quality of isolated DNA was checked by PCR amplification.The presumption on the elimination of PCR inhibitors from DNA samples was confirmed.

La société Nanobactérie développe un traitement thermique innovant contre le cancer qui repose sur l‘utilisation de nanoparticules d‘oxyde de fer d‘origine bactérienne, appelées magnétosomes. Celles-ci sont injectées directement dans la tumeur puis activées par le champ magnétique alternatif. Cette activation crée une augmentation locale de la température provoquant la destruction de la tumeur, sans affecter les tissus sains environnants. Afin d‘éviter les problèmes de toxicité liés à la présence d‘endotoxines bactériennes à la surface des magnétosomes, un processus de purification est utilisé. Il permet l‘élimination de toute la membrane organique immunogène et de garder ainsi le minéral responsable de l‘activité thermique. Cependant, l‘élimination de cette membrane entraîne l‘agrégation des magnétosomes. La première étape de ce travail de thèse a donc consisté à stabiliser les magnétosomes purifiés, et l'‘identification du meilleur revêtement a été évaluée. Dans une deuxième partie, une nouvelle modalité de chauffage a été mise au point pour augmenter l‘efficacité de l‘hyperthermie magnétique dans la destruction de cellules cancéreuses. / The Nanobactérie company develops a novel strategy of cancer treatment using iron oxide nanoparticles of bacterial origin, called magnetosomes. These nanoparticles are injected directly into the tumor and then activated by an alternating magnetic field. Activated nanoparticles trigger a highly localized rise of temperature, inducing the destruction of the tumor without any adverse effects on adjacent healthy tissues. To avoid the problems of toxicity caused by the presence of bacterial endotoxin which present on the surface of magnetosomes extracted from bacteria, a process of purification is realized to eliminate all the immunogenic organic membrane and keep only the mineral responsible for the thermal activity. However, since elimination of this membrane causes the aggregation of the magnetosomes which become unstable in aqueous solution, the first part of this work consisted in stabilizing the purified magnetosomes by a modification of their surface. The identification of the best coating was then evaluated. Moreover, in the second part of this work, a new heating modality was assessed to increase the efficiency of the magnetic hyperthermia in the destruction of cancer cells.