TATIANA SANTANA BALOGH

TATIANA SANTANA BALOGH

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Direct radiolabeling of PVP-nanogel from 99mTcO4
2023 - BALOGH, TATIANA S.; MARQUES, FABIO N.; KADLUBOWSKI, SLAWOMIR; LUGAO, ADEMAR B.
Nanogels are considered promising drug delivery systems for different pathologies, mainly associated with neurological disease, by intranasal administration since drug transport occurs via the olfactory nerve, causing rapid delivery to the brain. The present work aimed to evaluate a protocol for 99mTc labeling of poly(N-vinylpyrrolidone) (PVP) nanogel synthesized by an electron beam for future in vivo biodistribution assays. 10 mM PVP K-90 solution saturated with N2O was irradiated by e-beam using a dose of 7 kGy and a dose rate of 5.35 kGy/s. Nanoparticles characteristic was evaluated by DLS technique to determine the Rh and SLS to determine the Mw and Rg. Rg/Rh and ρcoil were calculated. The sample was morphologically characterized using AFM. The same analyzes were performed with a non-irradiated PVP solution. Radiolabeling was performed by mixing 0.55 mg of SnCl2.2H2O in 50 μL of HCl 0.1 M with (A) 450 μL 0.2 M NaOAc buffer, pH 4.1; (B) 200 μL 0.2 M NaOAc buffer, pH 4.1 and 0.5 M NaHCO3 buffer, pH 7.26; (C) filtered solution B in a 0.22 μm syringe filter. To the solutions (A), (B), and (C) were added 200 μL of nanogel (8.9 mg of PVP K-90), 100 μL of 99mTcO4- (860-980 μCi), and the samples were stirred at 500 rpm for 90 minutes at room temperature. The reaction was assessed by W3MM paper/acetone chromatography at the end of the process. All solutions were filtered through a 0.22 μm filter to remove 99mTcO2, as a previously validated process, and the radioactivity in the filter and the solution was measured. Finally, the solutions were concentred in the Amicon® (10 kD), and the radioactivity of the filtered and retained solution were measured too. The solution remaining on the filter was diluted with 300 μl of purified water and the concentration process was repeated twice. Filter content and the sum of filtered solutions 1 and 2 had the radioactivity measured to check labeling efficiency. Nanogel was obtained with an average for Rh of 12.49 nm, Rg of 6.8 nm, Mw of 1.32 x 106 g/mol, ρcoil of 786.98, and Rg/Rh of 0.620. High relief spherical structures were observed in the AFM images instead of the low roughness film observed in the non-irradiated PVP solution. Chromatographic analysis of the sample prepared only with NaOAc buffer (final pH 3.8) and of the sample with the mixture of buffers without previous filtration (final pH 6.8) indicated, respectively, 99.89 and 99.68% associated with the formation of 99mTc-PVP nanogel or 9mTc-colloid. In contrast, the sample prepared with the mixture of buffers and previously filtered (final pH 6.8) showed 80.10% of nonreduced 99mTcO4. Filtration results at 0.22 μm showed that the 9mTccolloid remains 100% retained in the filter, while free 99mTcO4 and 99mTc-PVP nanogel are filtered. Amicon® filtration confirmed 95.75% and 92% of 99mTc-PVP nanogel formation in the samples with NaOAc buffer and a mixture of buffers without previous filtration, respectively. It was possible to synthesize nanogel by electron beam, obtaining an average Rh of 12.49 nm. The labeling process with 99mTcO4- showed a high radiochemical yield in samples prepared with NaOAc buffer and a mixture of buffers without previous filtration.
Influence of argon and nitrous oxide on the synthesis of PVP nanogels prepared by gamma radiation
2020 - BALOGH, T.S.; KADLUBOWSKI, S.; BONTURIM, E.; LUGAO, A.B.; VARCA, G.H.
Nanogels are innovative systems with great potential for use in chemotherapy, disease diagnosis, release of bioactive substances, vaccines, cell culture systems, biocatalysis, in the generation of bioactive scaffolds in regenerative medicine among other applications. The definition of this material can be directly derived from the definition of polymeric gel, that is, a two-component system consisting of a permanent three-dimensional network of linked polymer chains and solvent molecules filling the pores of this network. Its internal structure is similar to that of hydrogels however presents particle size range varying from 0 to 100 nm leading to several advantages. Nanogel production methods involve intramolecular crosslinking that can be achieved using ionizing radiation. This method avoids the addition of any additives allowing the reaction to be carried out in a pure polymer-solvent system and the production of nanogels for biomedical applications free from monomer and crosslinking agents or surfactants. In this work influence of argon and nitrous oxide on the formation of nanogels by gamma irradiation has been evaluated. The samples were prepared in duplicate in multipurpose cobalt-60 gamma irradiator using a 25 mM PVP solution. Samples were irradiated in argon and nitrous oxide conditions with doses from 1 kGy up to 25 kGy with 10 kGy/h dose rate. These samples were morphologically characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) as well as the pristine PVP solution. The mean particle size of the samples and the polydispersity index was performed in equipment Zetasizer Nano ZS - Malvern® and the determination of radius of gyration and molecular weight was performed in equipment Heleos - Wyatt®. It was observed in the conditions evaluated that saturation with argon or nitrous oxide promoted similar results except for 25 kGy dose. At this dose larger mean particle size and radius of gyration were observed in the sample saturated with nitrous oxide.
Synthesis and characterization of PVP nanogels prepared by gamma radiation using 60Co source
2019 - BALOGH, T.S.; KADLUBOWSKI, S.; BONTURIM, E.; VARCA, G.; LUGAO, A.B.
Nanogels are promising and innovative systems in nanometer scale, with particle size range varying from 0 to 100 nm, of great potential in nanomedicine, pharmaceutics and bionanotechnology. They present several advantages such as capacity of injection into the circulation reaching target tissues and ability to deliver their payloads locally and intracellularly. Nanogels are defined as two-component system on nanometer scale consisting of a permanent three-dimensional network of linked polymer chains, and molecules of a solvent filling the pores of this network. They are formed by intramolecular crosslinking that can be achieved by the use of ionizing radiation, this method allows the formation of nanogels free of additives, rendering them non-toxic, a fundamental requirement for biomedical application. In this work, five samples of nanogels were developed using a 25 mM PVP solution. The samples were saturated with argon and prepared in multipurpose cobalt-60 gamma irradiator using doses of 1, 2, 5, 10 and 25 kGy at a dose rate of 10 kGy/hour corresponding, respectively, to samples A, B, C, D and E. These samples were morphologically characterized using atomic force microscopy (AFM) as well as the pristine PVP solution. The mean particle size of the samples as well as the determination of polydispersity index was performed in equipment Zetasizer Nano ZS - Malvern® and the determination of radius of gyration and molecular weight was realized in equipment Heleos - Wyatt®. The mean particle size of the samples A, B, C, D and E, were, respectively, 41.89, 46.85, 61.04, 62.79 and 62.11 nm and the mean particle size of the pristine PVP solution was 43.28 nm. The AFM results revealed the presence of spherical nanostructures in the samples prepared with dose equal to or more than 5 kGy (samples C, D and E). Under the conditions evaluated in the study the morphological characterization of the nanogels revealed that the doses of 5 kGy, 10 and 25 kGy are the most suitable doses for the nanogel formation as it led to spherical structures when compared to the other conditions assayed.
Estudo de purificação de Mo-99 por sublimação em forno tubular
2017 - DAMASCENO, MARCOS O.; LIMA, VINICIUS S.; BALOGH, TATIANA S.; FORBICINI, CHRISTINA A.L.G. de O.
Introdução: O 99Mo é um radioisótopo importante devido ao seu produto de decaimento - 99mTc, que atua como marcador molecular em cerca de 80% dos exames diagnósticos (Eur. J. Nucl. Med. Mol. Imag. 36;795,2009). Em muitos países, são empregadas técnicas cromatográficas para a obtenção do 99Mo de fissão de alta pureza, podendo ainda incluir etapas de complexação, precipitação ou sublimação dependendo do processo adotado. O projeto do reator multipróposito brasileiro (RMB) prevê a produção de radioisótopos, como 99Mo via fissão do 235U (Sci. Am. 98;82,2010). O nosso laboratório vem realizando estudos de possíveis etapas de purificação de 99Mo, visando o desenvolvimento de novas rotas de produção. Objetivo: Apresentar resultados preliminares de testes nas principais variáveis da etapa de sublimação do 99Mo como parte do processo de purificação. Os testes incluíram temperatura e tempo de sublimação, taxa de aquecimento e fluxo de gás de arraste, visando redução do tempo de processo e a máxima eficiência de recuperação de 99Mo. Métodos: Os experimentos partiram de uma solução de NH4MoO4 20 g.L-1 contendo uma pequena quantidade de 99Mo como radiotraçador, simulando uma solução em uma dada etapa do processo de purificação. Uma alíquota de 1 mL foi reservada para referência, enquanto outra alíquota de 1 mL foi levada à secura em um cadinho de platina sobre uma placa aquecida. O cadinho foi introduzido em um tubo de quartzo de um forno horizontal e aquecido. Um fluxo de ar para arraste dos vapores foi estabelecido. Após o resfriamento o tubo foi lavado internamente com 10 mL de solução de NaOH 1 M, uma alíquota de 1 mL foi retida desta solução, para contagem da atividade e cálculo de rendimento. As amostras foram analisadas em detector gama Ge hiperpuro em 739 KeV. Resultados: Foram observados depósitos de MoO3 no interior do tubo nas regiões próximas à saída do forno. Os testes com temperaturas já partir de 750°C mostraram excelentes rendimentos de recuperação (98 % ± 0,7). Devido à reduzida massa de óxido presente nas amostras, nos testes com temperatura de 800°C o tempo de sublimação de 5 mim foi suficiente para obter a saída de praticamente todo o material do cadinho. As curvas de aquecimento do forno são determinantes para a celeridade do processo, deste modo taxas de aquecimento de até 30 °C.min-1 foram aplicadas sem prejuízos de recuperação de 99Mo, valores maiores não foram testados por limitações do equipamento. Fluxos de arraste aplicados entre 3 e 9 mL.h-1 possibilitaram a formação de anéis bem definidos de MoO3 depositados a aproximadamente 10 cm do cadinho, facilmente visível dentro do tubo de quartzo, enquanto que sob fluxos acima de 15 mL.h-1 os depósitos apresentam-se mais difusos e com aumento de perdas por arraste. Conclusão: A técnica de sublimação em forno tubular permite a obtenção do 99Mo com elevada pureza e reduzidas perdas. A análise dos resultados permitirá melhor configuração dos parâmetros do forno, contribuindo para a maximização do rendimento de recuperação com redução do tempo total de processo. Os próximos testes incluirão amostras com (NH4)2SO4 ou (NH4)HCO3, simulando outras soluções de extração do molibdênio em um estágio prévio a sublimação.