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A nanociência e a nanotecnologia vêm abrindo inúmeros desenvolvimentos de dispositivos e sistemas em escala nanométrica, com novas organizações moleculares, propriedades e funções distintas. Nesse contexto, as nanopartículas magnéticas poliméricas são compósitos formados por materiais magnéticos com tamanhos de partículas entre 1 e 100 nm combinados com polímeros funcionais. São materiais bem conhecidos e têm sido amplamente estudados devido às suas aplicações em diversas áreas tecnológicas. Nas áreas biológica e médica, as aplicações incluem separação e imobilização de enzimas e proteínas, melhoria nas técnicas de imagem de ressonância magnética para diagnóstico e sistemas de liberação controlada de fármacos. Neste trabalho, proteínas foram imobilizadas na superfície de um biopolímero combinado com partículas superparamagnéticas de magnetita para formar o compósito magnético. Utilizou-se o biopolímero quitosana, reticulada e funcionalizada com glutaraldeído, aplicável em ensaios biológicos. Obtiveram-se 3 tipos de compósitos magnéticos, os quais foram nomeados QM1Glu, QM2NaGlu e QM3Glu. Foram caracterizados por difratometria de raios X, microscopia eletrônica de varredura, magnetometria de amostra vibrante, calorimetria exploratória diferencial, termogravimetria e espectroscopia por infravermelho. Foram avaliados quanto à imobilização das proteínas albumina de soro bovino (SAB), colágeno e tripsina. A imobilização das proteínas no biopolímero ocorreu em 30 min de incubação. O compósito magnético de quitosana não funcionalizada (QM3) também foi avaliado. Para a tripsina verificou-se que QM3 apresentou maior potencial de imobilização do que QM3Glu. Após 30 dias, QM3-Trip e QM3Glu-Trip ainda apresentavam a tripsina ativada. Foram demonstradas a atividade e a cinética enzimática da QM3Glu-trip com o substrato BApNA. / Nanoscience and nanotechnology have opened up numerous developments of devices and systems on the nanometer scale, with new molecular organization, properties and functions. In this context, the polymeric magnetic nanoparticles are composites formed by magnetic materials with a particle size between 1 and 100 nm combined with functional polymers. They are well-known and have been widely studied because of its applications in various technology areas. Applications on the biological and medical areas include separation and immobilization of enzymes and proteins, improved techniques of magnetic resonance imaging and diagnostic systems for controlled drug delivery. In this work, proteins were immobilized on the surface of a biopolymer combined with superparamagnetic particles of magnetite. The biopolymer chitosan was used, cross-linked and functionalized with glutaraldehyde, applicable to the biological assays. Three types of magnetic composites were obtained, which were called QM1Glu, QM2NaGlu and QM3Glu. They were characterized by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, differential scanning calorimetry, thermogravimetry and infrared spectroscopy. They were evaluated concerning the immobilization of the proteins bovine serum albumin (BSA), collagen and trypsin. The study showed that the immobilization of proteins on the biopolymer occurred in 30 min of incubation. The magnetic composite of nonfunctionalized chitosan (QM3) was also evaluated. For trypsin, it was found that the immobilization potential of QM3 was higher than that observed for QM3Glu. After 30 days, the trypsin of the QM3-Trip and QM3Glu-Trip was still with activity. The activity and the enzyme kinetics of the QM3Glu-Trip with the substrate BApNA were demonstrated.

A nanociência e a nanotecnologia vêm abrindo inúmeros desenvolvimentos de dispositivos e sistemas em escala nanométrica, com novas organizações moleculares, propriedades e funções distintas. Nesse contexto, as nanopartículas magnéticas poliméricas são compósitos formados por materiais magnéticos com tamanhos de partículas entre 1 e 100 nm combinados com polímeros funcionais. São materiais bem conhecidos e têm sido amplamente estudados devido às suas aplicações em diversas áreas tecnológicas. Nas áreas biológica e médica, as aplicações incluem separação e imobilização de enzimas e proteínas, melhoria nas técnicas de imagem de ressonância magnética para diagnóstico e sistemas de liberação controlada de fármacos. Neste trabalho, proteínas foram imobilizadas na superfície de um biopolímero combinado com partículas superparamagnéticas de magnetita para formar o compósito magnético. Utilizou-se o biopolímero quitosana, reticulada e funcionalizada com glutaraldeído, aplicável em ensaios biológicos. Obtiveram-se 3 tipos de compósitos magnéticos, os quais foram nomeados QM1Glu, QM2NaGlu e QM3Glu. Foram caracterizados por difratometria de raios X, microscopia eletrônica de varredura, magnetometria de amostra vibrante, calorimetria exploratória diferencial, termogravimetria e espectroscopia por infravermelho. Foram avaliados quanto à imobilização das proteínas albumina de soro bovino (SAB), colágeno e tripsina. A imobilização das proteínas no biopolímero ocorreu em 30 min de incubação. O compósito magnético de quitosana não funcionalizada (QM3) também foi avaliado. Para a tripsina verificou-se que QM3 apresentou maior potencial de imobilização do que QM3Glu. Após 30 dias, QM3-Trip e QM3Glu-Trip ainda apresentavam a tripsina ativada. Foram demonstradas a atividade e a cinética enzimática da QM3Glu-trip com o substrato BApNA. / Nanoscience and nanotechnology have opened up numerous developments of devices and systems on the nanometer scale, with new molecular organization, properties and functions. In this context, the polymeric magnetic nanoparticles are composites formed by magnetic materials with a particle size between 1 and 100 nm combined with functional polymers. They are well-known and have been widely studied because of its applications in various technology areas. Applications on the biological and medical areas include separation and immobilization of enzymes and proteins, improved techniques of magnetic resonance imaging and diagnostic systems for controlled drug delivery. In this work, proteins were immobilized on the surface of a biopolymer combined with superparamagnetic particles of magnetite. The biopolymer chitosan was used, cross-linked and functionalized with glutaraldehyde, applicable to the biological assays. Three types of magnetic composites were obtained, which were called QM1Glu, QM2NaGlu and QM3Glu. They were characterized by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, differential scanning calorimetry, thermogravimetry and infrared spectroscopy. They were evaluated concerning the immobilization of the proteins bovine serum albumin (BSA), collagen and trypsin. The study showed that the immobilization of proteins on the biopolymer occurred in 30 min of incubation. The magnetic composite of nonfunctionalized chitosan (QM3) was also evaluated. For trypsin, it was found that the immobilization potential of QM3 was higher than that observed for QM3Glu. After 30 days, the trypsin of the QM3-Trip and QM3Glu-Trip was still with activity. The activity and the enzyme kinetics of the QM3Glu-Trip with the substrate BApNA were demonstrated.

O carbono, em suas muitas formas distintas, tem sido largamente empregado como material adsorvente, do tratamento de água à tecnologia industrial em virtude de sua boa performance, baixo custo e compatibilidades biológica e ambiental. Nesta tese foi verificada a associação sinérgica entre carvão ativo e nanopartículas superparamagnéticas de óxido de ferro ensejando a exploração entre a capacidade adsortiva e o magnetismo para o desenvolvimento de processos de remoção de contaminantes de meios aquosos e melhorando sua análise por meio de concentração magnética. Para este propósito, nanopartículas magnéticas recobertas com ácidos oleico ou esteárico foram especialmente preparadas e combinadas com carvão ativo em proporções variadas (1, 5, 10, 20, 25, 50 % m/m), seguindo rigoroso controle químico. Os materiais de carbono magnetizáveis mantém suas afinidades química e característica porosa do material precursor com alguma diminuição de sua área superficial, embora exibindo uma forte atração por campos magnéticos externos, permitindo sua fácil concentração e remoção. Estes materiais foram extensivamente caracterizados por técnicas como BET, FTIR, XRD, DLS, SEM, TG/DTA, VSM e SQUID. Por conveniência, o compósito a 10 % de nanopartículas de magnetita foi escolhido como o principal a ser utilizado na maioria das aplicações exibindo ampla área superficial (700 m2.g-1), volume e diâmetro médio de poro (0,487 cc.g-1 e 8,5 nm, respectivamente) e uma magnetização de saturação de 5 emu.g-1, com histerese desprezível à temperatura ambiente. Suas características adsorventes foram exploradas com sucesso na captura de corantes orgânicos (pararosanilina e azul de metileno), nitrobenzeno, bisfenol-A e BTEX (benzeno, tolueno, etilbenzeno e o,m,p-xilenos), bem como para íons de metais pesados como Hg(II), Pb(II) e Ag(I) em solução aquosa. Estudos eletroanalíticos foram feitos explorando o efeito de pré-concentração magnética na superfície do eletrodo após realizar estudos de adsorção envolvendo o levantamento de isotermas afim de investigar parâmetros como capacidade adsortiva e constantes de adsorção. Em todos os casos, um elevado aumento de aumento na sensibilidade foi obtido através do confinamento magnético em relação aos métodos convencionais. Desta forma, o emprego do compósito de carbono com nanopartículas de óxido de ferro superparamagnéticas demonstrou ser uma ferramenta poderosa a ser explorada em Química Analítica e Ambiental. / Carbon in many distinct forms has been widely employed as absorbing material in industrial and water technology because of its good performance, low cost and bio/environmental compatibility. In this doctoral thesis, a synergistic association of activated carbon with superparamagnetic Fe3O4 nanoparticles was carried out, aiming the exploitation of their combined absorption capability and magnetism, for developing new processes of removing contaminants from water and improving their analysis by means of magnetic concentration effect. For this purpose, magnetite nanoparticles coated with stearic or oleic acids were specially prepared and combined with activated carbon, at several proportions (1, 5, 10, 20, 25, 50 % m/m), following a rigorous chemical and analytical control. The magnetized carbon materials kept the original porous characteristics and molecular affinity of the original absorber, with some decrease of the active surface area, but exhibiting a strong attraction by the magnetic field, allowing their easy concentration and removal. Such materials were extensively characterized by BET, FTIR, XRD, DLS, SEM, TG/DTA, VSM and SQUID techniques. For convenience, the carbon material containing 10 % of magnetite was elected as principal, exhibiting a surface area of 700 m2 g-1, average volume and porous diameter of 0,487 cm3 g-1 and 8,5 nm, respectively, and a saturation magnetization of 5 emu g-1, with null hysteresis at room temperature. Its absorbing characteristics were successfully explored for the capture of organic dyes (pararosaniline, and methylene blue), bisphenol-A, and BTEX (benzene, toluene, ethylbenzene, and o,m,p-xilene), as well as hazardous, heavy metal ions, such as Hg(II), Pb(II) and Ag(I) in aqueous solution. Electroanalytical studies were carried out by exploring the magnetic pre-concentration effect on the electrodes, after performing a detailed adsorption study involving the construction of isotherms, in order to evaluate the equilibrium and mass capacity parameters. In all the cases, a great increase of sensitivity was attained by the magnetic confined method, in relation to the conventional methods. In this way, the use of carbon with superparamagnetic nanoparticles demonstrated a powerful strategy to be explored in environmental and analytical chemistry.

O carbono, em suas muitas formas distintas, tem sido largamente empregado como material adsorvente, do tratamento de água à tecnologia industrial em virtude de sua boa performance, baixo custo e compatibilidades biológica e ambiental. Nesta tese foi verificada a associação sinérgica entre carvão ativo e nanopartículas superparamagnéticas de óxido de ferro ensejando a exploração entre a capacidade adsortiva e o magnetismo para o desenvolvimento de processos de remoção de contaminantes de meios aquosos e melhorando sua análise por meio de concentração magnética. Para este propósito, nanopartículas magnéticas recobertas com ácidos oleico ou esteárico foram especialmente preparadas e combinadas com carvão ativo em proporções variadas (1, 5, 10, 20, 25, 50 % m/m), seguindo rigoroso controle químico. Os materiais de carbono magnetizáveis mantém suas afinidades química e característica porosa do material precursor com alguma diminuição de sua área superficial, embora exibindo uma forte atração por campos magnéticos externos, permitindo sua fácil concentração e remoção. Estes materiais foram extensivamente caracterizados por técnicas como BET, FTIR, XRD, DLS, SEM, TG/DTA, VSM e SQUID. Por conveniência, o compósito a 10 % de nanopartículas de magnetita foi escolhido como o principal a ser utilizado na maioria das aplicações exibindo ampla área superficial (700 m2.g-1), volume e diâmetro médio de poro (0,487 cc.g-1 e 8,5 nm, respectivamente) e uma magnetização de saturação de 5 emu.g-1, com histerese desprezível à temperatura ambiente. Suas características adsorventes foram exploradas com sucesso na captura de corantes orgânicos (pararosanilina e azul de metileno), nitrobenzeno, bisfenol-A e BTEX (benzeno, tolueno, etilbenzeno e o,m,p-xilenos), bem como para íons de metais pesados como Hg(II), Pb(II) e Ag(I) em solução aquosa. Estudos eletroanalíticos foram feitos explorando o efeito de pré-concentração magnética na superfície do eletrodo após realizar estudos de adsorção envolvendo o levantamento de isotermas afim de investigar parâmetros como capacidade adsortiva e constantes de adsorção. Em todos os casos, um elevado aumento de aumento na sensibilidade foi obtido através do confinamento magnético em relação aos métodos convencionais. Desta forma, o emprego do compósito de carbono com nanopartículas de óxido de ferro superparamagnéticas demonstrou ser uma ferramenta poderosa a ser explorada em Química Analítica e Ambiental. / Carbon in many distinct forms has been widely employed as absorbing material in industrial and water technology because of its good performance, low cost and bio/environmental compatibility. In this doctoral thesis, a synergistic association of activated carbon with superparamagnetic Fe3O4 nanoparticles was carried out, aiming the exploitation of their combined absorption capability and magnetism, for developing new processes of removing contaminants from water and improving their analysis by means of magnetic concentration effect. For this purpose, magnetite nanoparticles coated with stearic or oleic acids were specially prepared and combined with activated carbon, at several proportions (1, 5, 10, 20, 25, 50 % m/m), following a rigorous chemical and analytical control. The magnetized carbon materials kept the original porous characteristics and molecular affinity of the original absorber, with some decrease of the active surface area, but exhibiting a strong attraction by the magnetic field, allowing their easy concentration and removal. Such materials were extensively characterized by BET, FTIR, XRD, DLS, SEM, TG/DTA, VSM and SQUID techniques. For convenience, the carbon material containing 10 % of magnetite was elected as principal, exhibiting a surface area of 700 m2 g-1, average volume and porous diameter of 0,487 cm3 g-1 and 8,5 nm, respectively, and a saturation magnetization of 5 emu g-1, with null hysteresis at room temperature. Its absorbing characteristics were successfully explored for the capture of organic dyes (pararosaniline, and methylene blue), bisphenol-A, and BTEX (benzene, toluene, ethylbenzene, and o,m,p-xilene), as well as hazardous, heavy metal ions, such as Hg(II), Pb(II) and Ag(I) in aqueous solution. Electroanalytical studies were carried out by exploring the magnetic pre-concentration effect on the electrodes, after performing a detailed adsorption study involving the construction of isotherms, in order to evaluate the equilibrium and mass capacity parameters. In all the cases, a great increase of sensitivity was attained by the magnetic confined method, in relation to the conventional methods. In this way, the use of carbon with superparamagnetic nanoparticles demonstrated a powerful strategy to be explored in environmental and analytical chemistry.

Un des enjeux majeurs dans le domaine du magnétisme moléculaire est de mieux comprendre et prévoir, dans les composés à base moléculaire, les corrélations qui existent entre les propriétés structurales (modulables à partir de méthodes de synthèse de type « bottom-up ») et les propriétés magnétiques. En particulier, la compréhension et la maîtrise de l’anisotropie magnétique à l’échelle locale est primordiale, notamment en vue de concevoir des molécules-aimants avec de plus hautes températures de blocage. Dans ce contexte, ce travail de thèse s’organise autour de deux grands axes. La première partie se concentre sur la détermination et la caractérisation de l’anisotropie magnétique locale dans des complexes moléculaires d’ions de transition de faible nucléarité. La diffraction de neutrons polarisés (PND) nous a permis, pour la première fois, de mettre clairement en évidence le tenseur de susceptibilité magnétique locale dans un complexe moléculaire mononucléaire de Fe3+ Bas-Spin ainsi que dans deux complexes, mononucléaire et dinucléaire, de Co2+ Haut-Spin. Cette approche novatrice mène à l’établissement de relations magnéto-structurales claires et directes, en reliant les directions magnétiques locales propres à l’environnement de coordination des ions métalliques et en particulier aux axes locaux de distorsion. Nous avons également mené l’étude originale d’un complexe à transition de spin thermo-induite de Mn3+ par diffusion inélastique de neutrons (INS) dans les deux phases Haut-Spin (HS) et Bas-Spin (BS). Cette étude nous a conduits à la proposition d’un modèle d’hamiltonien de spin anisotrope dans les deux états HS et BS, en relation avec la structure du complexe. Dans une seconde partie plus exploratoire de la thèse, nous avons mené une étude complète des propriétés structurales et magnétiques de nanoparticules ferromagnétiques d’analogue du bleu de Prusse CsNiCr, par diffusion de neutrons aux petits angles (SANS). Les effets de taille, d’organisation et de concentration sur leurs propriétés superparamagnétiques ont ainsi été clairement mis en évidence. En particulier, nous avons mis en exergue, pour les particules de plus petite taille (5 nm de diamètre), une contribution magnétique qui résulte de la manifestation d’un phénomène collectif, tandis que celles de plus grande taille (28 nm de diamètre) apparaissent être dans un état complètement multidomaine. / One of the major issues in the field of molecular magnetism is to better understand and predict the correlations between the structural properties of molecule-based compounds and their magnetic properties, all of which may be tunable using “bottom-up” synthesis methods. In particular, the understanding and control of the magnetic anisotropy at the atomic scale is essential, especially with the aim to design Single-Molecule Magnets (SMM) with higher blocking temperatures. In this context, this thesis work is focused on two mains subjects. The first part deals with the determination and the characterization of the local magnetic anisotropy in low-nuclearity molecular complexes based on transition ions. Polarised neutron diffraction (PND) allows us, for the first time, to directly access the local susceptibility tensor in a Low-Spin Fe3+ mononuclear complex as well as in two, mononuclear and dinuclear, High-Spin Co2+ complexes. This innovative approach leads to the establishment of unique and direct magneto-structural correlations, by relating the local magnetic principal directions with the coordination environment of the metallic ions and, in particular, with the local distortion axes. We have also carried out an original investigation by inelastic neutron scattering (INS) of a Mn3+ thermo-induced spin-transition compound in both High-Spin (HS) and Low-Spin (LS) states. On the basis of this study, we were able to propose an anisotropic spin-Hamiltonian model in both HS and LS phases, and their relationships with the structure of the molecule are discussed. In a second more exploratory part of the thesis, we have carried out by small-angle neutron scattering (SANS) a complete study of the structural and magnetic properties of Prussian blue analogues (PBA) ferromagnetic nanoparticles CsNiCr. The effects of size, organization and concentration on their superparamagnetic properties have been clearly highlighted. In particular, a strong magnetic contribution has been observed for the smallest particles (5 nm diameter) which results from the manifestation of a collective process, while the biggest (28 nm diameter) appear to be in a multi-domain state.

Μαγνητικά νανοσωματίδια οξειδίων του σιδήρου παρασκευάσθηκαν μέσω της αλκαλικής συμπύκνωσης και ελεγχόμενης καταβύθισης συμπλόκων ιόντων FeII, υπό την παρουσία τυχαίου συμπολυμερούς PAA-co-MA. Οι παράμετροι της σύνθεσης μεταβλήθηκαν με σκοπό την απομόνωση προϊόντων που να εμφανίζουν τις καλύτερες μαγνητικές ιδιότητες. Όλα τα προϊόντα εμφάνισαν υψηλή κολλοειδή σταθερότητα σε υδατικά μέσα χαμηλής ιοντικής ισχύος, ενώ ο σιδηρομαγνητικός τους χαρακτήρας έδειξε να ποικίλει από ασθενής μέχρι αρκετά ισχυρός, όπως προέκυψε μετά τον χαρακτηρισμό τους με μαγνητοφόρηση και μαγνητική υπερθερμία με εναλλασόμενο μαγνητικό πεδίο. Το μέσο μέγεθος των νανοκρυσταλλιτών ήταν διαφορετικό σε κάθε προϊόν κυμαινόμενο από περίπου 3 έως 14 nm, όπως προσδιορίστηκε μέσω XRD. Η ανάλυση με ΤΕΜ έδειξε ότι στο προϊόν που εμφανίζει τις καλύτερες μαγνητικές ιδιότητες σχηματίζονται πλειάδες νανοσωματιδίων πυκνής διάταξης, και στις οποίες αποδίδεται η βελτιωμένη απόκριση σε μαγνητικά πεδία. Τα άλλα προϊόντα εμφάνισαν μικρότερα μεγέθη κρυσταλλιτών και διαφορετικά δομικά χαρακτηριστικά. Τα κολλοειδή καταβυθίζονταν κατόπιν αύξησης της ιοντικής ισχύος του διαλύτη. Για τον λόγο αυτό αποφασίστηκε η μελέτη της αντίδρασης σύζευξης των εξωτερικών καρβοξυλικών ομάδων του πολυμερικού φλοιού με mPEG-NH2, δεδομένου ότι η PEG αυξάνει σημαντικά τη σταθερότητα των κολλοειδών. Παρά το γεγονός ότι χρησιμοποιήθηκαν κοινά αντιδραστήρια σύζευξης, μόνο υπό πολύ ειδικές συνθήκες η απόδοση της αντίδρασης ήταν ικανοποιητική, οπότε και προέκυψαν σταθερά κολλοειδή σε συνθήκες υψηλής ιοντικής ισχύος. Τέλος, τα προϊόντα αξιολογήθηκαν για την ικανότητά τους να επάγουν υπερθερμία και μελετήθηκε ο χρόνος χαλάρωσης Τ2, ο οποίος σχετίζεται άμεσα με την ενίσχυση της αντίθεσης στην απεικόνιση μέσω μαγνητικού συντονισμού. Τέλος, ένα από τα προϊόντα, μελετήθηκε in vitro και in νίνο, προκειμένου να αξιολογηθεί η βιοσυμβατότητα του. Τα συστήματα αυτά παρουσιάζουν πολύ ενδιαφέρουσες ιδιότητες ώστε να τροποποιηθούν και να μελετηθούν περεταίρω ως θεραπευτικά ή/και διαγνωστικά νανοϋλικά. / Μagnetic nanoparticles of iron oxides were synthesized through condensation and controlled precipitation of a FeII complex, in alkaline environment, in the presence of a random copolymer PAA-co-MA, as polymeric corona. The synthetic parameters were varied with the aim of isolating products exhibiting the best magnetic properties. All products displayed high colloidal stability in low ionic strength aqueous media, while their ferromagnetic properties varied from weak to quite strong, as deduced after the characterization with magnetophoresis and magnetic hyperthermia with alternating magnetic field. The average crystallite size, as determined through XRD, varied from 8 to 14 nm depending on the product. TEM analysis showed that the product displaying the best magnetic properties formed clusters of densely packed nanocrystallites, leading to interesting superstructural motifs. All the other products displayed smaller crystallite sizes and different structural characteristics. The colloids precipitated upon increase of the ionic strength of the solvent (H2O) with NaCl. Therefore, it was decided to study the conjugation of the outer carboxyl groups of the polymeric corona with mPEG-NH2, since PEG is known to increase significantly the stability of colloids. Despite the fact that common conjugation reagents were used, only under specific conditions the yied of the reaction was appropriately high in order the resultant colloids to be stable in a high ionic strength (isotonic) medium. Finally the products were evaluated for their performance in magnetic hyperthermia and for contrast enhancement in magnetic resonance imaging, by studying the T2 relaxation time. One of the products was furthermore studied by in vitro and in vivo systems, in order to evaluate its biocompatibility. These colloidal systems exhibit very interesting properties in order to be further modified and studied as therapeutic and / or diagnostic (theragnostic) nanomaterials.

L’un des enjeux majeurs en nanomédecine est de développer des systèmes capables à la fois de permettre un diagnostic efficace et également de servir de plateforme thérapeutique pour combattre les infections et les neuro-dégénérescences. Dans cette optique, et afin d’améliorer la détection de tumeurs, des agents de contraste ont été développés dans le but d’augmenter le rapport signal sur bruit. Parmi ces agents, les nanoparticules (NPs) d’oxyde de fer superparamagnétiques (SPIOs) et les quantum dots (QDs) sont des candidats idéaux et ont reçu une grande attention depuis une vingtaine d’années. De surcroit, leurs propriétés spécifiques dues à leurs dimensions nanométriques et leurs formes permettent de moduler leur bio-distribution dans l’organisme. L’opportunité de revêtir ces NPs biocompatibles par des couches de polymères devraient permettre d’améliorer la stabilité de ces nanomatériaux dans l’organisme. Et par conséquent, favoriser leur biodistribution et également leur conférer de nouvelles applications en l’occurrence des applications biomédicales. Dans ce travail de thèse, nous avons développé de nouveaux systèmes thermo-répondant basés sur un cœur SPIOs ou QDs qui sont capables, à la fois, de transporter un principe actif anticancéreux, i.e. la doxorubicine (DOX) et de le relarguer dans le milieu physiologique à une température contrôlée. Deux familles de NPs ont été synthétisées. La première concerne des NPs de Fe3O4 SPIO qui ont été modifiées en surface par un copolymère thermorépondant biocompatible à base de 2-(2-methoxy) méthacrylate d’éthyle (MEO2MA), oligo (éthylène glycol) méthacrylate (OEGMA). La seconde famille, consiste en des NPs de ZnO recouverte du même copolymère. Pour la première fois, le copolymère de type P(MEO2MAX-OEGMA100-X) a été polymérisé par activateur-régénéré par transfert d’électron-polymérisation radicalaire par transfert d’atome (ARGET-ATRP). La polymérisation et copolymérisation ont été initiées à partir de la surface. Les NPs cœur/coquilles ont été caractérisées par microscopie électronique à transmission (TEM), analyse thermogravimétrique (TGA), etc. Nous avons montré que l’efficacité du procédé ARGET-ATRP pour modifier les surfaces des NPs de SiO2, Fe3O4 et de ZnO. L’influence de la configuration de la chaîne de copolymère et des propriétés interfaciales avec le solvant ou le milieu biologique en fonction de la température a été étudiée. Nous avons montré que les propriétés magnétiques des systèmes coeur/coquilles à base de Fe3O4 ne sont influencées que par la quantité de polymère greffée contrairement au QDs qui vient leur propriété optique réduire au-delà de la température de transition. Ce procédé simple et rapide que nous avons développé est efficace pour le greffage de nombreux copolymères à partir de surfaces de chimie différentes. Les expériences de largage et relarguage d’un molécule modèle telle que la DOX ont montré que ces nanosystèmes sont capables de relarguer la DOX à une température bien contrôlée, à la fois dans l’eau que dans des milieux complexes tels que les milieux biologique. De plus, les tests de cytocompatibilité ont montré que les NPs coeur/coquilles ne sont pas cytotoxiques en fonction de leur concentration dans le milieu biologique. A partir de nos résultats, il apparaît que ces nouveaux nanomatériaux pourront être envisagés comme une plateforme prometteuse pour le traitement du cancer / One of the major challenges in nanomedicine is to develop nanoparticulate systems able to serve as efficient diagnostic and/or therapeutic tools against sever diseases, such as infectious or neurodegenerative disorders. To enhance the detection and interpretation contrast agents were developed to increase the signal/noise ratio. Among them, Superparamagnetic Iron Oxide (SPIO) and Quantum Dots (QDs) nanoparticles (NPs) have received a great attention since their development as a liver contrasting agent 20 years ago for the SPIO. Furthermore, their properties, originating from the nanosized dimension and shape, allow different bio-distribution and opportunities beyond the conventional chemical imaging agents. The opportunity to coat those biocompatible NPs by a polymer shell that can ensure a better stability of the materials in the body, enhance their bio-distribution and give them new functionalities. It has appeared then that they are very challenging for medicinal applications. In this work, we have developed new responsive SPIO and QDs based NPs that are able to carry the anticancer drug doxorubicin (DOX) and release it in physiological media and at the physiological temperature. Two families of NPs were synthesized, the first one consist in superparamagnetic Fe3O4 NPs that were functionalized by a biocompatible responsive copolymer based on 2-(2-methoxy) ethyl methacrylate (MEO2MA), oligo (ethylene glycol) methacrylate (OEGMA). The second family consists in the ZnO NPs coated by the same copolymer. For the first time, P(MEO2MAX-OEGMA100-X) was grown by activator regenerated by electron transfer–atom radical polymerization (ARGET-ATRP) from the NPs surfaces by surface-initiated polymerization. The core/shell NPs were fully characterized by the combination of transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and by the physical properties of the nanostructures studied. We demonstrate the efficiency of the ARGET-ATRP process to graft polymers and copolymers at the surface of Fe3O4 and ZnO NPs. The influence of the polymer chain configuration (which leads to the aggregation of the NPs above the collapse temperature of the copolymer (LCST)) was studied. We have demonstrated that the magnetic properties of the core/shell Fe3O4-based nanostructures were only influenced by the amount of the grafted polymer and no influence of the aggregation was evidenced. This simple and fast developed process is efficient for the grafting of various co-polymers from any surfaces and the derived nanostructured materials display the combination of the physical properties of the core and the macromolecular behavior of the shell. The drug release experiments confirmed that DOX was largely released above the co-polymer LCST. Moreover, the cytocompatibility test showed that those developed NPs do not display any cytotoxicity depending on their concentration in physiological media. From the results obtained, it can be concluded that the new nanomaterials developed can be considered for further use as multi-modal cancer therapy tools

L’ingénierie du tissu osseux vise à concevoir un substitut tissulaire associant des cellules ostéoprogénitrices à une matrice tridimensionnelle capable de promouvoir la reconstruction osseuse, ouvrant la voie au développement de thérapeutiques substitutives à la pratique de la greffe dont les limitations sont bien connues.Le but de ce travail a été de développer un nouveau produit d’ingénierie tissulaire (PIT) destiné à la régénération osseuse constitué i) d’une matrice tridimensionnelle poreuse constituée de polysaccharides naturels biodégradables, ii) de cellules souches adultes issues du tissu adipeux humain (ADSCs) et d’identifier les conditions de culture optimales permettant le développement d’un produit fonctionnel pour une utilisation clinique. Nos résultats montrent que l’architecture et la composition de la matrice macroporeuse polysaccharidique permet de guider la différenciation ostéoblastique des ADSCs, en l’absence de facteurs ostéogéniques, et notamment en conditions de culture dynamique, grâce à l’organisation cellulaire en agrégats promouvant les interactions cellulaires. Les ADSCs peuvent être marquées à l’aide de nanoparticules superparamagnétiques et suivies in vivo de façon non invasive par imagerie par résonnance magnétique (IRM) au sein des matrices après leur implantation en site sous-cutané chez la souris. Les images IRM montrent que le matériau permet de délivrer une partie des cellules au niveau du site d’implantation participant probablement à un processus de réparation tissulaire. Enfin, en vue d’applications cliniques, un milieu de culture sans sérum répondant aux conditions GMP (Good Manufacturing Practices) pour la différenciation ostéoblastique a été développé par un industriel et validé au cours de ce travail de thèse.En conclusion de ces travaux, l’association d’une matrice macroporeuse composée de polysaccharides avec des ADSCs dans des conditions de culture spécifiques, en conditions dynamiques, semble pertinente et prometteuse pour des applications cliniques en ingénierie du tissu osseux. / Bone tissue engineering may associate osteoprogenitor cells to a tridimensional scaffold that can promote tissue reconstruction in order to replace bone grafting strategies whose limitations are well known. This study aims to develop a new tissue-engineered construct for bone regeneration constituted by i) a tridimensional polysaccharide-based scaffold, ii) adult stem cells extracted from human adipose tissue and identify the best culture conditions needed to develop a functional construct for clinical use. Our results show that this macroporous scaffold offers, without any osteoinductive factors, a suitable architecture and composition for driving osteoblastic differentiation of ADSCs especially when placing the tissue-engineered construct in dynamic conditions, thanks to cell aggregate conformation promoting cell-to-cell interactions. Thanks to ADSCs labeling, the tissue-engineered construct can be tracked in vivo in a non invasive way by magnetic resonance imaging (MRI), after their subcutaneous implantation. Results evidenced that this scaffold behaves as a cell carrier for of holding in its own cell fraction and delivering another fraction to the site of implantation for inducing a better tissue regeneration process. Finally, a serum free medium meeting standards GMPs (Good Manufacturing Practices) has been developed for inducing ADSCs osteoblastic differentiation as a first step towards clinical application.In conclusion, this polysaccharide-based scaffold associated with ADSCs, cultured under low fluid flow in a new bioreactor device, could be a relevant and promising tissue engineered construct for bone tissue engineering applications.