Nanotechnology offers a great potential do design fertilizers with unique properties capable to boost the plant productivity. However, the nanoparticles environmental fate and their toxic responses still need to be deeply investigated to their safe use. This study aims to investigate the effect of copper oxide (nCuO) and magnetite nanoparticles (nFe3O4) on the germination and seedling development of Phaseolus vulgaris L. Seeds were treated in nanoparticles dispersions in a wide range of concentrations (1, 10, 100 and 1 000 mg L-1) and incubated in a germination chamber during 5 days. Different sized nCuO (25, 40 and <80 nm) and polyethylene glycol (PEG) coated nFe3O4 were evaluated. Although both nCuO and nFe3O4 treatments did not affected the germination rate, seedling weight gain was promoted by 40 nm CuO at 100 mg Cu L-1 and inhibited by 1 000 mg Cu L-1 of 25 nm CuO and positive control (CuSO4). Among the tested nCuO, the higher chemical reactivity was found for the 25 nm CuO, and this may partially explain the observed deleterious effects. Seeds treated in nFe3O4-PEG at 1 000 mg Fe L-1 increased radicle elongation compared to the negative control (water), while Fe2+/Fe3+ (aq) (positive control) and bare nFe3O4 at 1 000 mg Fe L-1 treatments reduced the radicle of the seedlings. The growth promoted by the PEG-coated nanoparticles can be justified by the higher water uptake induced by the PEG, and also by its lower chemical reactivity compared to the bare nanoparticles. This was reinforced by enzymatic assays since nFe3O4-PEG treatment was also the least harmful to the alpha-amylase activity. X-ray fluorescence spectroscopy (XRF) showed that most of the Cu and Fe incorporated by the seeds remained in the seed coat, specially in the hilum region, and X-ray tomography indicated that Fe3O4-PEG penetrated in this structure. X-ray absorption spectroscopy (XAS) unraveled that the Cu and Fe chemical environment of the nCuO and nFe3O4-PEG treated seeds persisted mostly in its primitive form. These results contribute to the understanding of how nCuO, nFe3O4 and nFe3O4-PEG interact with common bean seeds and seedlings and highlights its potential use in seed priming / A nanotecnologia oferece um grande potencial para o desenvolvimento de fertilizantes com propriedades únicas, capazes de impulsionar a produtividade das plantas. Contudo, o destino ambiental e os efeitos tóxicos das nanopartículas ainda necessitam ser profundamente investigados para o seu uso seguro. Este estudo visa investigar o efeito das nanopartículas de óxido de cobre (nCuO) e magnetita (nFe3O4) na germinação e desenvolvimento das plântulas de Phaseolus vulgaris L. As sementes foram tratadas em dispersões de nanopartículas em diversas concentrações (1, 10, 100 and 1 000 mg L-1) e incubadas em uma câmara de germinação durante 5 dias. Diferentes tamanhos de nCuO (25, 40 e <80 nm) e nFe3O4 recoberta com polietileno glicol (PEG) e foram avaliados. Embora ambos tratamentos de nCuO e nFe3O4 não afetaram a taxa de germinação, o ganho de massa das plântulas foi promovido pela nCuO de 40 nm à 100 mg Cu L-1 e inibido pelos tratamentos de nCuO de 25 nm e controle positivo (CuSO4) à 1 000 mg Cu L-1. Dentre as nCuO testadas, a maior reatividade química foi encontrada para a nCuO de 25 nm, e isso pode explicar parcialmente os efeitos deletérios desta nanopartícula. Sementes tratadas com nFe3O4-PEG à 1 000 mg Fe L-1 aumentaram o alongamento das radículas em comparação ao controle negativo (água), enquanto que os tratamentos Fe2+/Fe3+ (aq) (controle positivo) e nFe3O4 sem recobrimento à 1 000 mg Fe L-1 reduziram as radículas das plântulas. O crescimento promovido pelas nanopartículas recobertas com PEG pode ser justificado pela maior absorção de água induzido pelo PEG, e também pela sua baixa reatividade química comparada às nanopartículas sem recobrimento. Isso foi reforçado por ensaios enzimáticos uma vez que o tratamento de nFe3O4-PEG foi também o menos prejudicial à atividade da alfa-amilase. A espectroscopia de fluorescência de raios-X (XRF) mostrou que a maior parte do Cu e do Fe incorporados pelas sementes permaneceu no tegumento, especialmente na região do hilo, e a tomografia de raios-X indicou que nFe3O4-PEG penetrou nesta estrutura. A espectroscopia de absorção de raios-X (XAS) revelou que o ambiente químico do Cu e do Fe das sementes tratadas com nCuO e nFe3O4-PEG persistiram majoritariamente em sua forma primitiva. Estes resultados contribuem para o entendimento de como nCuO, nFe3O4 e nFe3O4-PEG interagem com sementes de feijão e destaca seu potencial uso no tratamento de sementes

Nanotechnology offers a great potential do design fertilizers with unique properties capable to boost the plant productivity. However, the nanoparticles environmental fate and their toxic responses still need to be deeply investigated to their safe use. This study aims to investigate the effect of copper oxide (nCuO) and magnetite nanoparticles (nFe3O4) on the germination and seedling development of Phaseolus vulgaris L. Seeds were treated in nanoparticles dispersions in a wide range of concentrations (1, 10, 100 and 1 000 mg L-1) and incubated in a germination chamber during 5 days. Different sized nCuO (25, 40 and <80 nm) and polyethylene glycol (PEG) coated nFe3O4 were evaluated. Although both nCuO and nFe3O4 treatments did not affected the germination rate, seedling weight gain was promoted by 40 nm CuO at 100 mg Cu L-1 and inhibited by 1 000 mg Cu L-1 of 25 nm CuO and positive control (CuSO4). Among the tested nCuO, the higher chemical reactivity was found for the 25 nm CuO, and this may partially explain the observed deleterious effects. Seeds treated in nFe3O4-PEG at 1 000 mg Fe L-1 increased radicle elongation compared to the negative control (water), while Fe2+/Fe3+ (aq) (positive control) and bare nFe3O4 at 1 000 mg Fe L-1 treatments reduced the radicle of the seedlings. The growth promoted by the PEG-coated nanoparticles can be justified by the higher water uptake induced by the PEG, and also by its lower chemical reactivity compared to the bare nanoparticles. This was reinforced by enzymatic assays since nFe3O4-PEG treatment was also the least harmful to the alpha-amylase activity. X-ray fluorescence spectroscopy (XRF) showed that most of the Cu and Fe incorporated by the seeds remained in the seed coat, specially in the hilum region, and X-ray tomography indicated that Fe3O4-PEG penetrated in this structure. X-ray absorption spectroscopy (XAS) unraveled that the Cu and Fe chemical environment of the nCuO and nFe3O4-PEG treated seeds persisted mostly in its primitive form. These results contribute to the understanding of how nCuO, nFe3O4 and nFe3O4-PEG interact with common bean seeds and seedlings and highlights its potential use in seed priming / A nanotecnologia oferece um grande potencial para o desenvolvimento de fertilizantes com propriedades únicas, capazes de impulsionar a produtividade das plantas. Contudo, o destino ambiental e os efeitos tóxicos das nanopartículas ainda necessitam ser profundamente investigados para o seu uso seguro. Este estudo visa investigar o efeito das nanopartículas de óxido de cobre (nCuO) e magnetita (nFe3O4) na germinação e desenvolvimento das plântulas de Phaseolus vulgaris L. As sementes foram tratadas em dispersões de nanopartículas em diversas concentrações (1, 10, 100 and 1 000 mg L-1) e incubadas em uma câmara de germinação durante 5 dias. Diferentes tamanhos de nCuO (25, 40 e <80 nm) e nFe3O4 recoberta com polietileno glicol (PEG) e foram avaliados. Embora ambos tratamentos de nCuO e nFe3O4 não afetaram a taxa de germinação, o ganho de massa das plântulas foi promovido pela nCuO de 40 nm à 100 mg Cu L-1 e inibido pelos tratamentos de nCuO de 25 nm e controle positivo (CuSO4) à 1 000 mg Cu L-1. Dentre as nCuO testadas, a maior reatividade química foi encontrada para a nCuO de 25 nm, e isso pode explicar parcialmente os efeitos deletérios desta nanopartícula. Sementes tratadas com nFe3O4-PEG à 1 000 mg Fe L-1 aumentaram o alongamento das radículas em comparação ao controle negativo (água), enquanto que os tratamentos Fe2+/Fe3+ (aq) (controle positivo) e nFe3O4 sem recobrimento à 1 000 mg Fe L-1 reduziram as radículas das plântulas. O crescimento promovido pelas nanopartículas recobertas com PEG pode ser justificado pela maior absorção de água induzido pelo PEG, e também pela sua baixa reatividade química comparada às nanopartículas sem recobrimento. Isso foi reforçado por ensaios enzimáticos uma vez que o tratamento de nFe3O4-PEG foi também o menos prejudicial à atividade da alfa-amilase. A espectroscopia de fluorescência de raios-X (XRF) mostrou que a maior parte do Cu e do Fe incorporados pelas sementes permaneceu no tegumento, especialmente na região do hilo, e a tomografia de raios-X indicou que nFe3O4-PEG penetrou nesta estrutura. A espectroscopia de absorção de raios-X (XAS) revelou que o ambiente químico do Cu e do Fe das sementes tratadas com nCuO e nFe3O4-PEG persistiram majoritariamente em sua forma primitiva. Estes resultados contribuem para o entendimento de como nCuO, nFe3O4 e nFe3O4-PEG interagem com sementes de feijão e destaca seu potencial uso no tratamento de sementes

This thesis provides several nanomaterial systems that can be used as contrast agents in magnetic resonance imaging (MRI) and for optical fluorescence imaging. Nanoparticle systems described in this thesis fall under three categories: (a) graphene oxide-nanoparticle composites for MRI contrast agent application, (b) core-shell nanoparticles for MRI contrast agent application and (c) nanoparticle systems for both MRI and optical fluorescence imaging. In the case of graphene oxide based nano-composites, the following observations were made: (i) in the case of graphene oxide-Fe3O4 nanoparticle composite, it was observed that high extent of oxidation of the graphene oxide and large spacing between the graphene oxide sheets containing Fe3O4 nanoparticles provides the optimum structure for yielding a very high transverse proton relaxivity value, (ii) in the case of graphene oxide-Gd2O3 nanoparticle composite, it was observed that this composite exhibits high value for both longitudinal and transverse relaxivity values making it a potential materials for multi-contrast study of pathologies with a single agent, (iii) in the case of graphene oxide-CoFe2O4 nanoparticle composites, it was observed that an increase in the reflux time of the reaction mixture containing this composite led to appreciable variations in the proton relaxivity values. Transverse relaxivity value of the water protons increased monotonically with increase in the reflux time. Whereas, the longitudinal relaxivity value initially increased and then decreased with increase in the reflux time. In the case of coreshell nanoparticles for MRI contrast agent application two different core-shell systems were investigated. They are MnFe2O3-Fe3O4 core-shell nanoparticles and CoFe2O4-MnFe2O4 coreshell nanoparticles. Investigations of both the core-shell nanoparticle systems revealed that the proton relaxivity value obtained in the dispersion of the core-shell nanoparticles was considerably greater than the proton relaxivity value obtained in the presence of single phase nanoparticles of the core and shell phases. Very high value of transverse relaxivity in the case core-shell nanoparticles was due to the large magnetic inhomogeneity created by the core-shell nanoparticles in the water medium surrounding it. In the case of nanoparticle systems for both MRI and optical fluorescence imaging, two different systems were investigated. They were CoFe2O4-ZnO core-shell nanoparticles and Gd doped ZnS nanoparticles [Zn1-xGdxS, x= 0.1, 0.2 and 0.3] formed on graphene oxide sheets or coated with chitosan. In the case of CoFe2O4-ZnO core-shell nanoparticles it was observed that fluorescent CoFe2O4-ZnO core-shell nanoparticles with the unique geometry in which CoFe2O4 ferrite nanoparticles agglomerates were present within larger sized hollow ZnO capsules yields very high value of transverse proton relaxivity when compared to the proton relaxivity value exhibited by the individual CoFe2O4-ZnO coreshell nanoparticles. In the case of Gd doped ZnS nanoparticles, two different systems were synthesized and the values of the longitudinal and transverse proton relaxivity obtained were compared. These systems were (i) graphene oxide- Zn1-xGdxS (x= 0.1, 0.2 and 0.3) nanoparticle composites and (ii) chitosan coated Zn1-xGdxS (x= 0.1, 0.2 and 0.3) nanoparticles. It was observed that Gd doped ZnS nanoparticles in both cases exhibit both longitudinal and transverse relaxivity values. The relaxivity values showed a clear dependence on the composition of the nanoparticles and the nanoparticle environment (presence and absence of graphene oxide). It was also observed that Gd doped ZnS nanoparticle can be used for florescence imaging.