MARGARETH KAZUYO KOBAYASHI DIAS FRANCO
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Artigo IPEN-doc 30461 Structural characterization of silver nanoparticles produced by biogenic synthesis using SAXS2024 - RIBEIRO JUNIOR, ARI; YOKAICHIYA, FABIANO; MONERJAN, ENELI; LEMKE, KARINA; GUILGER-CASAGRANDE, MARIANA; LIMA, RENATA; FRACETO, LEONARDO; FRANCO, MARGARETH K.K.D.; KELLERMANN, GUINTHERNanotechnology applied to the agricultural sector has highlighted in recent decades, making important contributions, including systems for pest control as biogenic nanoparticles. These nanoparticles are used to control phytopathogens, demonstrating the need to understand its composition, mechanisms of action and toxicity. Their capping of biomolecules, derived from the organism used in the synthesis, contributes to their stability and biological activity. Ag nanoparticles were produced by the fungus Trichoderma harzianum in aqueous solutions containing silver nitrate as a precursor for the silver nanoparticles. Some of the samples were exposed to the phytopathogenic fungus Sclerotinia sclerotiorum responsible for the white mold. After preparation, a fraction of the samples was submitted to physico-chemical processes to remove organic cap layer on nanoparticles surface formed during the preparation process. In this study we determined the effect of the phytopathogenic fungus and cap removal process in the average radius, radius dispersion, number density of the nanoparticles using small angle X-ray scattering (SAXS), where we considered their almost spherical shape in aqueous solution obtained by the biogenic route. The SAXS data analyses suggest that the presence of the pathogenic fungus results in a diminution of number and total volume of Ag NPs without significant effects on average radius and radius dispersion. Our results also indicate that the physic-chemical process to remove the organic cap surrounding the Ag NPs leads to a decrease in the fraction of the smaller nanoparticles.Artigo IPEN-doc 24815 Influence of the irradiation in cement for the Brazilian radioactive waste repositories2018 - FERREIRA, EDUARDO G.A.; YOKAICHIYA, FABIANO; MARUMO, JULIO T.; VICENTE, ROBERTO; GARCIA-MORENO, FRANCISCO; KAMM, PAUL H.; KLAUS, MANUELA; RUSSINA, MARGARITA; GUNTHER, GERRIT; JIMENEZ, CATALINA E.; FRANCO, MARGARETH K.K.D.Powerful characterization techniques have allowed detailing the investigation of cementitious materials that must endure for millennia as an engineered barrier in radioactive waste repositories. Cement is used in the repository, as waste immobilization matrix, structural material and an additional barrier against the contact of the waste with the biosphere. The material properties have to comply with requirements in respect to a number of parameters including homogeneity, permeability, and leachability, as well as withstand mechanical stress, heat, chemical and microbial attack, and the effects of ionizing radiation. The present study aims to investigate the behavior of cementitious materials contributing to the understanding of the processes that occur in hydrated cement under the environmental conditions of a repository and to estimate the durability of these materials. In this study was observed the changes caused by radiation, to which the material was exposed. A reference Portland cement paste and grout samples were compared with irradiated ones by X-ray diffraction and Tomography. Original and valuable results concerning the investigation of the influence of radiation on cement samples were also obtained by quasielastic scattering. These results are not accessible by others techniques.Artigo IPEN-doc 24321 Effects of doxorubicin on the structural and morphological characterization of solid lipid nanoparticles (SLN) using small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS)2018 - YOKAICHIYA, FABIANO; SCHMIDT, CHRISTIAN; STORSBERG, JOACHIM; VOLLRATH, MONT K.; ARAUJO, DANIELE R. de; KENT, BEN; CLEMENS, DANIEL; WINGERT, FRIEDRICH; FRANCO, MARGARETH K.K.D.Cancer is still a major public health problem. Leaving detection of early stages of tumors and other issues aside, minimizing unwarranted side effects, for example after clinical usage of a liposomal anticancer drug doxorubicin (Dox) formulation, is an unmet clinical problem and the focus of many studies. Using compounds typically used in the preparation of food and/or cosmetics to prepare drug carrier systems, we observed that sodium tetradecyl sulfate (STS) containing and soybean-oil based carriers are more efficient in reducing the viability of HeLa cells tumor cells in comparison to their respective counterparts. Here, we probe the doxorubicin (Dox) loading on structural properties of either soybean oil or coconut oil (Mygliol 812) formulations. Small angle neutron scattering (SANS) assays were performed using V16 instrument at Helmholtz-Zentrum Berlin (HZB) at 25, 37 and 40 C with two or 11m distance between detector and sample to assess a wide range in scattering vector Q. Combined with previous measurement using small angle X-ray scattering (SAXS), our results show that the Dox has different influence in the surface structure of the solid lipid nanoparticles (SLN) and also affects the fractality in the vesicle aggregates when the concentration of the drug is altered, for Mygliol and soybean oil SLN drug delivery carrier systems.