Nanopartículas de óxidos de ferro e nióbio com diferentes recobrimentos: síntese, caracterização e avaliação do potencial biológico / Iron oxide nanoparticles with different coatings and niobium oxide nanoparticles: synthesis, characterization and assessment of biological potential

Nanopartículas (NPs) tem ganhado notoriedade crescente em aplicações biomédicas. Podendo ser constituídas de diversos materiais, NPs tem sido empregadas como agentes de contraste, na liberação direcionada e controlada de fármacos, em terapia para tratamento de câncer, em catálise heterogênea, entre outras aplicações. As nanopartículas magnéticas de óxido de ferro (MNP) destacam-se pela multiplicidade de aplicações, apesar de serem pouco caracterizadas quanto à toxicidade celular. Outras nanopartículas com excelente potencial são as constituídas de óxido de nióbio (NbONPs), as quais merecem atenção especial, pois o Brasil é detentor de 98% das reservas comercialmente viáveis deste elemento. Neste trabalho NPs destes dois metais de transição (ferro e nióbio) foram sintetizadas, almejando entender suas interações com materiais, biomoléculas e meios biológicos. Diversas metodologias foram desenvolvidas e testadas com intuito de otimizar a morfologia e o rendimento da preparação, resultando na escolha de decomposição térmica para MNP e, para NbONPs, escolheu-se a impregnação do óxido de nióbio sobre uma matriz de MNPs recobertas com sílica. No caso das MNPs, procedeu-se ao recobrimento das mesmas com lipídeos zwitteriônicos (Dioleilfosfatidilcolina (DOPC)) e carregados positivamente (Brometo de dioctadecildimetilamônio (DODAB)). Foram inicialmente caracterizadas as suas propriedades em diversos ambientes biológicos para posteriormente realizarmos ensaios de citoxicidade em queratinócitos humanos (HaCaT). Avaliamos também a degradação das NPs em diferentes pH, bem como, a interação das mesmas com membranas miméticas de vesículas gigantes unilamelares (GUVs - Giant Unilamellar Vesicles), com visualização microscópica. As MNPs recobertas com DODAB mostraram-se mais tóxicas para os queratinócitos em cultura e também causaram lise das GUVs. No caso das NbONPs, avaliou-se a acidez proveniente do Nb2O5 e o seu potencial em catálise heterogênea, bem como a avaliação da citotoxicidade em HaCaT revelou um potencial uso biomédico

Nanoparticles (NPs) have received increasing attention in biomedical applications. NPs can be constituted by different materials and have been used as contrast agents, in drug delivery, in cancer therapy, in heterogeneous catalysis, among other applications. Magnetic iron oxide nanoparticles (MNP) are notable for their multiplicity of applications, although they are poorly characterized for cellular toxicity. Other nanoparticles with excellent potential are made of niobium oxide (NbONPs), which deserve special attention, since Brazil holds 98% of the commercially viable reserves of this element. In this Thesis, NPs of these two transition metals (iron and niobium) were synthesized, aiming to understand their interactions with materials, biomolecules and media biological. Several methodologies were developed and tested to optimize the morphology and yield of the preparation, resulting in the choice of thermal decomposition for MNPs and, for NbONPs, the impregnation of niobium oxide on a matrix of silica-coated MNPs. In the case of MNPs, they were also coated with lipid zwitterionics (Dioleoyl phosphocholine (DOPC)) and positively charged (Dimethyldioctadecylammonium bromide (DODAB)) lipids. Its properties were initially characterized in several biological environments for later cytotoxicity assays in human keratinocytes (HaCaT). It evaluated the degradation of the NPs in different pH, as well as their interaction with giant unilamellar vesicle (GUVs) mimetic membranes, with microscopic visualization. MNPs coated with DODAB were more toxic to keratinocytes in culture and caused lysis of GUVs. In the case of NbONPs, acidity from Nb2O5 was evaluated in heterogeneous catalysis, as well as the evaluation of HaCaT cytotoxicity revealed a potential biomedical use

Cultivar variability of iron uptake mechanisms in rice (Oryza sativa L.).

Rice (Oryza sativa L.) is the most important staple food in the world. It is rich in genetic diversity and can grow in a wide range of environments. Iron (Fe) deficiency is a major abiotic stress in crop production and in aerobic soils, where Fe forms insoluble complexes, and is not readily available for uptake. To cope with Fe deficiency, plants developed mechanisms for Fe uptake, and although rice was described as a Strategy II plant, recent evidence suggests that it is capable of utilizing mechanisms from both Strategies. The main objective of this work was to compare two cultivars, Bico Branco (japonica) and Nipponbare (tropical japonica), to understand if the regulation of Fe uptake mechanisms could be cultivar (cv.)dependent. Plants of both cultivars were grown under Fe-deficient and -sufficient conditions and physiological and molecular responses to Fe deficiency were evaluated. Bico Branco cv. developed more leaf chlorosis and was more susceptible to Fe deficiency, retaining more nutrients in roots, than Nipponbare cv., which translocated more nutrients to shoots. Nipponbare cv. presented higher levels of Fe reductase activity, which was significantly up-regulated by Fe deficiency, and had higher expression levels of the Strategy I-OsFRO2 gene in roots, while Bico Branco cv. induced more genes involved in Strategy II.These new findings show that rice cultivars have different responses to Fe deficiency and that the induction of Strategy I or II may be rice cultivar-dependent, although the utilization of the reduction mechanisms seems to be an ubiquitous advantage.

Speciation of iron in the aquatic environment.

Iron is one of the basic metals occurring in the aquatic environment and it is considered a macroelement with regard to live organisms. This metal has a broad range of applications that, together with factors conditioning its chemical transitions, results in the occurrence of many iron species in water. Depending on water and land development type, as well as the use of water for household and industrial purposes, iron may be found in different forms, including solutions, colloids or suspensions, made up by both simple ions or particles and complex organic or inorganic compounds. Due to changing properties of the different iron forms and their varying influence, it is critical to gain information about its speciation. In this article we present information about iron species, including nano-iron forms, in various aquatic environments (i.e., marshland, ocean waters) as well as the exemplary methods for separating iron from iron-containing environmental samples.

Pore-scale characterization of biogeochemical controls on iron and uranium speciation under flow conditions.

Etched silicon microfluidic pore network models (micromodels) with controlled chemical and redox gradients, mineralogy, and microbiology under continuous flow conditions are used for the incremental development of complex microenvironments that simulate subsurface conditions. We demonstrate the colonization of micromodel pore spaces by an anaerobic Fe(III)-reducing bacterial species (Geobacter sulfurreducens) and the enzymatic reduction of a bioavailable Fe(III) phase within this environment. Using both X-ray microprobe and X-ray absorption spectroscopy, we investigate the combined effects of the precipitated Fe(III) phases and the microbial population on uranium biogeochemistry under flow conditions. Precipitated Fe(III) phases within the micromodel were most effectively reduced in the presence of an electron shuttle (AQDS), and Fe(II) ions adsorbed onto the precipitated mineral surface without inducing any structural change. In the absence of Fe(III), U(VI) was effectively reduced by the microbial population to insoluble U(IV), which was precipitated in discrete regions associated with biomass. In the presence of Fe(III) phases, however, both U(IV) and U(VI) could be detected associated with biomass, suggesting reoxidation of U(IV) by localized Fe(III) phases. These results demonstrate the importance of the spatial localization of biomass and redox active metals, and illustrate the key effects of pore-scale processes on contaminant fate and reactive transport.

Zinc y desnutrición / Zinc and undernutrition

Son cuatro los nutrientes en que su deficiencia es importante en niños: hierro, yodo, vitamina A y zinc. Más o menos se calcula que hay 2 billones de personas en el mundo con algún grado de déficit de zinc. Los pacientes que están en riesgo de presentar deficiencias de zinc son los recién nacidos con bajo peso al nacimiento, bien sea prematuros, desnutridos in útero o hijos de madres desnutridas, en los cuales sus depósitos están reducidos. A diferencia de otros oligoelementos o micronutrientes, determinar el estado de déficit no es fácil. Los niveles séricos de zinc, están influenciados por factores no dietarios como infección, estrés o actividad física extenuante; al igual que por el ciclo circadiano.

Four nutrient deficiency that is important in children, iron, iodine, vitamin A and zinc. More or less it is estimated that 2 billion people in the world with some degree of zinc deficiency. Patients who are at risk for zinc deficiency are infants with low birth weight, either premature or malnourished in utero, undernourished mothers, in which their deposits are reduced. Unlike other trace elements or micronutrients, determine the deficit is not easy. Serum levels of zinc are not influenced by dietary factors such as infection, stress or strenuous physical activity, as well as by the circadian cycle.

Alimentación complementaria / Supplementary feeding

La alimentación complementaria, se define como el proceso que se inicia con la introduccióngradual y paulatina de alimentos que sean diferentes a la leche materna o en su defecto a la fórmula infantil. La AAP, la ESPGHAN, la UNICEF y la OMS, recomiendan la lactancia materna exclusiva entre los 4 y 6 meses edad. Existe un mayor riesgo de alergia alimentaria en el niño menor. La evaluación de la alimentación del niño debe incluir, entre otros, conocer el tipo de alimentación láctea que recibió el niño; y que: los alimentos sean preparados de forma higiénica; los utensilios sean adecuados; hay adiversidad, variación y combinación de alimentos; el aporte energético sea el adecuado; la textura y consistencia de los alimentos vaya progresando y sea adecuado para su desarrollo neurológico; no haya ninguna intolerancia o reacción adversa respecto a la alimentación, y el crecimiento pondoestatural sea adecuado, entre otros.

Complementary feeding is defined as the process begins with the gradual and progressive introduction of foods that are different from breast milk or failing to infant formula. The AAP, theESPGHAN, UNICEF and WHO recommend exclusive breastfeeding between 4 and 6 monthsof age. There is an increased risk of food allergy in the minor child. The evaluation of the child's diet should include, among others, know the type of milk feeding the child received and that: the food is hygienically prepared, the tools are adequate, there is diversity, variation and combination offoods, the energy intake is adequate, the texture and consistency of food progresses and is suitablefor their neurological development, there is no intolerance or adverse reaction with respect tofood, and appropriate physical growth, among others.

Risk assessment due to environmental exposures to fibrous particulates associated with taconite ore.

In the early 1970s, it became a concern that exposure to the mineral fibers associated taconite ore processed in Silver Bay, Minnesota would cause asbestos-related disease including gastrointestinal cancer. At that time data gaps existed which have now been significantly reduced by further research. To further our understanding of the types of airborne fibers in Silver Bay we undertook a geological survey of their source the Peter Mitchell Pit, and found that there are no primary asbestos minerals at a detectable level. However we identified two non-asbestos types of fibrous minerals in very limited geological locales. Air sampling useful for risk assessment was done to determine the type, concentrations and size distribution of the population of airborne fibers around Silver Bay. Approximately 80% of the airborne fibers have elemental compositions consistent with cummingtonite-grunerite and the remaining 20% have elemental compositions in the tremolite-actinolite series. The mean airborne concentration of both fiber types is less than 0.00014 fibers per milliliter that is within the background level reported by the World Health Organization. We calculate the risk of asbestos-related mesothelioma and lung cancer using a variety of different pessimistic assumptions. (i) that all the non-asbestos fibers are as potent as asbestos fibers used in the EPA-IRIS listing for asbestos; with a calculated risk of asbestos-related cancer for environmental exposure at Silver Bay of 1 excess cancer in 28,500 lifetimes (or 35 excess cancers per 1,000,000 lifetimes) and secondly that taconite associated fibers are as potent as chrysotile the least potent form of asbestos. The calculated risk is less than 0.77 excess cancer case in 1,000,000 lifetimes. Finally, we briefly review the epidemiology studies of grunerite asbestos (amosite) focusing on the exposure conditions associated with increased risk of human mesothelioma.

Green primary explosives: 5-nitrotetrazolato-N2-ferrate hierarchies.

The sensitive explosives used in initiating devices like primers and detonators are called primary explosives. Successful detonations of secondary explosives are accomplished by suitable sources of initiation energy that is transmitted directly from the primaries or through secondary explosive boosters. Reliable initiating mechanisms are available in numerous forms of primers and detonators depending upon the nature of the secondary explosives. The technology of initiation devices used for military and civilian purposes continues to expand owing to variations in initiating method, chemical composition, quantity, sensitivity, explosive performance, and other necessary built-in mechanisms. Although the most widely used primaries contain toxic lead azide and lead styphnate, mixtures of thermally unstable primaries, like diazodinitrophenol and tetracene, or poisonous agents, like antimony sulfide and barium nitrate, are also used. Novel environmentally friendly primary explosives are expanded here to include cat[Fe(II)(NT)(3)(H(2)O)(3)], cat(2)[Fe(II)(NT)(4)(H(2)O)(2)], cat(3)[Fe(II)(NT)(5)(H(2)O)], and cat(4)[Fe(II)(NT)(6)] with cat = cation and NT(-) = 5-nitrotetrazolato-N(2). With available alkaline, alkaline earth, and organic cations as partners, four series of 5-nitrotetrazolato-N(2)-ferrate hierarchies have been prepared that provide a plethora of green primaries with diverse initiating sensitivity and explosive performance. They hold great promise for replacing not only toxic lead primaries but also thermally unstable primaries and poisonous agents. Strategies are also described for the systematic preparation of coordination complex green primaries based on appropriate selection of ligands, metals, and synthetic procedures. These strategies allow for maximum versatility in initiating sensitivity and explosive performance while retaining properties required for green primaries.

Determinación de niveles séricos de zinc, hierro y cobre en un grupo de estudiantes de la Universidad Nacional de Colombia (Santafé de Bogotá 1997-1998)

Objetivos. Establecer los niveles séricos de hierro, zinc y cobre en una población de estudiantes clínicamente sanos, determinar las posibles diferencias de estos micronutrientes por género y establecer correlaciones con algunos parámetros antropométricos. Materiales y Métodos. Se realizó un estudio aleatorio en estudiantes de IV semestre de Medicina, clínicamente sanos (28 mujeres y 30 hombres). Las muestras de sangre fueron recolectadas después de ayuno de 12 h en tubos secos y libres de contaminación exógena. Las concentraciones séricas de los oligoelementos se determinaron mediante espectometría de emisión atómica con plasma acoplado por inducción. Resultados. La talla y el peso fueron significativamente mayores en los hombres (p<0.0001 y p <0.0002 respectivamente), sin observarse diferencias significativas en el índice de masa corporal entre géneros. Las mujeres presentaron concentraciones séricas de hierro y zinc significativamente menores en comparación con los varones (p<0.005 y p<0.002 respectivamente). Discusión. Las diferencias entre los géneros fueron estadísticamente significativas para el hierro (p<0.005) y el zinc (p<0.002). Los niveles séricos de los micronutrientes no se correlacionaron con los parámetros antropométricos de las mujeres. En los varones, se observaron correlaciones negativas entre el índice de masa corporal y las concentraciones séricas de cobre y zinc y entre el peso y los niveles séricos de cobre (p<0.05). Conclusiones. Además de reportar los niveles séricos de tres micronutrientes y su relación con algunos parámetros antropométricos y comparar las concentraciones con reportes de la literatura, éste trabajo sugiere que en el grupo de estudio, las mujeres presentan un mayor riesgo de padecer deficiencias de hierro y de zinc que los varones

Contenido de zinc, cobre, hierro, calcio, fósforo y magnesio en leche materna en los primeros días de lactanción / Zinc, copper, iron, calcium, phosphorous and magnesium content of maternal milk at early stage of lactation

Se determinó, el contenido de Zn, Cu, Fe, Ca, P y Mg en leche temprana en 72 madres de la ciudad de Caracas. Las muestras fueron colectadas durante tres etapas de lactación: calostro (3 días), transicional (7 días) madura (21 días). Los cambios más marcados en las concentraciones de los elementos estudiados se observan principalmente durante las primeras semanas de lactación, tendiendo a estabilizarse hacia la tercera semana de lactación. El contenido de Zn, Cu, Fe, Ca, P y Mg en leche calostro, fue de 7,1 ñ 2,5 µg/ml, 0,52 ñ 0.15 µg/ml, 0,49 ñ 0,14 µg/ml, 214 ñ 62 µg/ml, 107 ñ 27 µg/ml y 33,3 ñ 5,5 µg/ml. En leche transicional 4,0 ñ 1,0 µg/ml, 0,5 ñ 0,10 µg/ml, 0,38 ñ µg/ml, 292 ñ 62 µg/ml, 213 ñ 36 µg/ml y 30,4 ñ 5,2 µg/ml y en leche madura 2,8 ñ 2,7 µg/ml, 0,47 ñ 0,08 µg/ml, 0,36 ñ 0,09 µg/ml, 224 ñ 49 µg/ml, 175 ñ 35 µg/ml y 25,2 ñ 3,3 µg/ml. Las concentraciones de los elementos traza estudiados (Zn, Fe, Cu) se mantienen dentro de los niveles considerados normales. Los valores de los elementos mayoritarios (Ca, P, Mg) son comparables a los reportados en la bibliografía para otros países. Estos resultados sugieren que el estado nutricional de esta población de madres es adecuado, para satisfacer las demandas del lactante en las primeras etapas de su vida

O leite pó fortificado com ferro e vitamina C como medida de intervencao no combate a anemia carencial ferropriva em criancas atendidas em Unidade Básica de Saúde / Use of fortified powdered milk for iron deficient anemia in children seen at a Basic Health Care Unit

Estudo realizado como o objetivo de verificar influencia do uso do leite em pó integral fortificado com ferro e vitamina C sobre os niveis dehemoglobina de 238 criancas de 6 a 18 meses de idade atendidas em Unidades Básica de Saúde. O leite em pó distribuído foi fortificado com 9 mg de ferro, sob a forma de sulfato ferroso, e 65 mg de vitamina C por 100 g de pó e distribuído aos beneficiários nas seguintes quantidades: 4 por més para menores de 1 año e 2 kg por més aos maiores. Realizaram-se avaliacoes clínicas, antropométricas e hematológicas (dosagem de hemoglobina (no momento anterior a cada 3 meses após iniciada a suplementacao Ao final do experimento, ainda havia disponibilidad de leite para prorrogar a intervencao em um grupo de 39 criancas que havia apresentado as piores evolucoes nos 6 meses iniciais. No momento inicial, 72,6 por ciento das criancas apresentavam anemia. Após 3 a 6 meses, este percentual reduziu-se 38,9 por ciento e 18.5 por ciento respectivamente. Aquellas acompñanhadas por 9 meses, restaram apenas 2,5 por ciento de criancas anémicas. As maiores prevaléncias foram encontradas nas faixas etárias dos 6 aos 12 meses e as mehores respostas dos 10 aos 18 meses. Em 30,7 por ciento das familias ocorreu a diluicao intrafamiliar do leite destinado ao beneficiario. Registraram-se decréscimos significantes da ocorréncia de anemia com ou sem diluicao intrafamiliar do leite, sem difrencas entre os dois grupos. O leite fortificado ñao alterou condicao nutriconal das criancas. Concluiuse que a fortificacao de alimentos, além de ser o método de eleicao para a prevencao da caréncia de ferro é excelente alternativa para auxiliar na recuperacao da anemia carencial ferropriva em menores de 2 anos

Suplementación de hierro en lactantes mapuches de la Provincia de Cautin, Chile / Iron supplementation in Chilean Mapuche infants

Con el propósito de profundizar la caracterización del metabolismo del hierro, en lactantes mapuches, se realizó un estudio de suplementación con Sulfato Ferroso (Fer-In-Sol) de 1.8 ml diarios durante 90 días, a 76 lactantes mapuches de 12 meses de edad, de ambos sexos, rurales, de la Provincia de Cautín. se evaluó la nutrición de hierro antes y después de la suplementación, mediante: Hemoglobina, Hematocrito, Saturación de Transferrina (Fe/IBC) y Ferritina Sérica. Para confirmar la ingesta del suplemento, se tomó en el domicilio de los lactantes, muestras de deposiciones para medir el hierro excretado. Para estudiar el aporte de hierro dietario, se aplicó la Encuesta Recordatorio 24 hrs (ER) y análisis Químico Proximal (AQP), en muestras de comidas obtenidas en los hogares de los lactantes. La prevalencia de anemia a los meses, antes de iniciar la suplementación fue de 28.3 por ciento, la que desapareció complementamente como producto de la intervención. El 65.3 por ciento de los lactantes, aumentaron su Hemoglobina en 1 g o más, lo que índica que eran anémicos al iniciar la suplementación. Es decir, mediante esta prueba terapéutica se pesquizó un 31 por ciento más de lactantes anémicos, lo que indica mayor sensibilidad de este método. La alta prevalencia de anemia se debe fundamentalmente, a la baja ingesta de hierro dietético, que según la ER alcanza un promedio de 2.8 ñ 1.2 mg de Fe/día, versus 4.8 ñ 4.0 mg de Fe/día, según AQP. La diferencia entre ambos aportes demostró que hay un proceso de contaminación ambiental de los alimentos, por el uso de utensilios de hierro y el gran contacto con la tierra. Este hecho también se pudo comprobar por la alta excreción de Fe a través de las deposiciones (140 mg de Fe/100 g deposiciones), cifra considerablemente más alta, que las reportadas en lactantes urbanos (30 mg de Fe/100 g deposiciones). Este método para medir la excreción de Fe del suplemento, no discrimina entre la excreción de la ingesta y la contaminación ambiental, que es extremadamente alta. Sin embargo, en el grupo suplementado, la excreción fue considerablemente más alta que en el grupo control, lo que estaría comprobado la ingesta de Fe. Para prevenir el desarrollo de anemia por carencia de hierro, en los lactantes, se hace imprescindible, dar un alimento fortificado con hierro, a partir de los 6 meses de vida como complemento de la leche materna