Agentes de contraste nanoestruturados a base de óxido de ferro : síntese, caracterização e avaliação toxicológica
Autor(a) principal: | |
---|---|
Data de Publicação: | 2018 |
Tipo de documento: | Tese |
Idioma: | por |
Título da fonte: | Biblioteca Digital de Teses e Dissertações da PUC_RS |
Texto Completo: | http://tede2.pucrs.br/tede2/handle/tede/8073 |
Resumo: | The present study focuses on the development of nanoparticles with an iron oxide magnetic core, with different biocompatible coatings, and on a comparative study of their toxicities. Uncoated and dextran-, chitosan-, polyethylene glycol- and silica-coated nanoparticles were synthesized. The addition of optical markers of the benzo-thiazoles class was also accomplished. The physico-chemical properties of the nano-particles were characterized, including their magnetic, optical and contrast properties in nuclear magnetic resonance imaging (relaxivities). In the particular case of nanopar-ticles functionalized with 6-OH-BTA-1 molecules, the affinity to the beta-amyloid pep-tide was also investigated. A second step was to evaluate the toxicological effects of these nanoparticles in vitro (using in VERO cells), and in vivo with zebrafish as an animal model. The size of the nanoparticles with the coatings ranged from 13 to 30 nm. Their crystalline structure was consistent with the ferrite spinel. The nanoparticles, independent of the coating, did not present residual magnetization and hysteresis, in-dicating superparamagnetic behaviour. For most nanoparticles, the r2 transverse re-laxivity values ranged from 76-64 mM-1.s-1, exceptfor uncoated and chitosan-coated nanoparticles, which present higher values, possibly due to the aggregation. The val-ues of r1 were similar for all nanoparticles (12.6 to 18 mM-1.s-1), with the exception of silica-coated nanoparticles (r1=2.1 mM-1.s-1). The r2/r1 ratios were between 4 and 17, typical of commercially available negative contrast-agents. The nanoparticles function-alized with benzothiazoles showed fluorescence with a Stokes shift of the emission peak of ~ 197 nm. The interaction of the beta-amyloid peptide with the 6-OH-BTA-1 molecule analyzed by fluorescence suppression is characterized by a static mecha-nism and Stern-Volmer constants of 1.53x104 mM-1 for the monomeric form, 1.40x104 mM -1 for oligomers) and 1.33x104 mM -1 for amyloid plaques.The in vitro toxicity assays indicated acceptable values of cell viability for iron concentration up to 2 mmol.L-1. The nanoparticles with the carboxysilane and polyethylene glycol showed higher biocom-patibility and silica-coated nanoparticles had the highest cytotoxicity. The in vivo as-says did not show significant changes in survival and hatchability rates, except for doses greater than 2 mmol.L-1 in the case of the chitosan-coated nanoparticles. The percentages of animals with anatomical alterations were similar between the treated and control groups. In the locomotion and exploration tests, only chitosan- and silica-coated nanoparticles induced significant changes. |
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Papaléo, Ricardo Meurerhttp://lattes.cnpq.br/1933730859000512http://lattes.cnpq.br/9837215819121108Oliveira, Elisa Magno Nunes de2018-05-23T15:10:26Z2018-03-20http://tede2.pucrs.br/tede2/handle/tede/8073The present study focuses on the development of nanoparticles with an iron oxide magnetic core, with different biocompatible coatings, and on a comparative study of their toxicities. Uncoated and dextran-, chitosan-, polyethylene glycol- and silica-coated nanoparticles were synthesized. The addition of optical markers of the benzo-thiazoles class was also accomplished. The physico-chemical properties of the nano-particles were characterized, including their magnetic, optical and contrast properties in nuclear magnetic resonance imaging (relaxivities). In the particular case of nanopar-ticles functionalized with 6-OH-BTA-1 molecules, the affinity to the beta-amyloid pep-tide was also investigated. A second step was to evaluate the toxicological effects of these nanoparticles in vitro (using in VERO cells), and in vivo with zebrafish as an animal model. The size of the nanoparticles with the coatings ranged from 13 to 30 nm. Their crystalline structure was consistent with the ferrite spinel. The nanoparticles, independent of the coating, did not present residual magnetization and hysteresis, in-dicating superparamagnetic behaviour. For most nanoparticles, the r2 transverse re-laxivity values ranged from 76-64 mM-1.s-1, exceptfor uncoated and chitosan-coated nanoparticles, which present higher values, possibly due to the aggregation. The val-ues of r1 were similar for all nanoparticles (12.6 to 18 mM-1.s-1), with the exception of silica-coated nanoparticles (r1=2.1 mM-1.s-1). The r2/r1 ratios were between 4 and 17, typical of commercially available negative contrast-agents. The nanoparticles function-alized with benzothiazoles showed fluorescence with a Stokes shift of the emission peak of ~ 197 nm. The interaction of the beta-amyloid peptide with the 6-OH-BTA-1 molecule analyzed by fluorescence suppression is characterized by a static mecha-nism and Stern-Volmer constants of 1.53x104 mM-1 for the monomeric form, 1.40x104 mM -1 for oligomers) and 1.33x104 mM -1 for amyloid plaques.The in vitro toxicity assays indicated acceptable values of cell viability for iron concentration up to 2 mmol.L-1. The nanoparticles with the carboxysilane and polyethylene glycol showed higher biocom-patibility and silica-coated nanoparticles had the highest cytotoxicity. The in vivo as-says did not show significant changes in survival and hatchability rates, except for doses greater than 2 mmol.L-1 in the case of the chitosan-coated nanoparticles. The percentages of animals with anatomical alterations were similar between the treated and control groups. In the locomotion and exploration tests, only chitosan- and silica-coated nanoparticles induced significant changes.O presente trabalho aborda o desenvolvimento de nanopartículas compostas por um núcleo magnético de óxido de ferro com diferentes revestimentos biocompatí-veis e estudo comparativo de suas toxicidades. Foram sintetizadas nanopartículas de óxido de ferro sem revestimento e com revestimentos de dextrana, quitosana, polieti-lenoglicol e sílica, e com a adição de marcadores ópticos da classe dos benzotiazóis. As propriedades físico-químicas das nanopartículas foram caracterizadas, incluindo as suas propriedades magnéticas, ópticas e de contraste em imagens por ressonância magnética nuclear (relaxividades), bem como a afinidade ao peptídeo beta-amiloide, no caso particular de funcionalização com a molécula 6-OH-BTA-1. Em uma segunda etapa, foram avaliados os efeitos toxicológicos dessas nanopartículas em ensaios bi-ológicos in vitro em células VERO, e in vivo tendo como animal modelo o peixe zebra. O tamanho das nanopartículas com revestimentos variou entre 13 a 30 nm, e estrutura cristalina coerente com o espinélio de ferrita. As nanopartículas não apresentaram magnetização residual e histerese, indicando superparamagnetismo, independente do revestimento. Para a maioria das nanopartículas, os valores de relaxividade transver-sal r2 variaram de 76-64 mM-1.s-1, com exceção das nanopartículas sem revestimento e de quitosana, os quais foram mais elevados, possivelmente devido ao efeito de agregação. Os valores de r1 foram semelhantes para todas as nanopartículas (12,6 a 18 mM-1.s-1), com exceção das nanopartículas de sílica (r1 = 2,1 mM-1.s-1). As razões r2/r1 foram entre 4 e 17, valores típicos de agentes de contraste negativos comercial-mente disponíveis. As nanopartículas funcionalizadas com os benzotiazóis mantive-ram sua fluorescência com deslocamentos de Stokes na ordem de 197 nm para o pico de emissão. As análises da interação do peptídeo beta-amiloide com a molécula 6-OH-BTA-1, mostraram valores de constante de Stern-Volmer para supressão de fluo-rescência de 1,53x104 mM-1 (monômero), 1,40x104 mM-1 (oligômero) e 1,33x104 mM-1 (placa), indicando quenching por um mecanismo estático. O peptídeo na forma mo-nomérica demonstrou maior facilidade de acesso às moléculas de 6-OH-BTA-1. Os resultados dos ensaios in vitro indicaram valores aceitáveis de viabilidade celular para concentração de ferro inferior a 2 mmol.L-1. As nanopartículas com o carboxisilano e polietilenoglicol demostraram maior biocompatibilidade e as nanopartículas de sílica tiveram a maior citotoxicidade. Os resultados dos ensaios in vivo não mostraram alte-rações significativas na taxa de sobrevivência e de eclosão do corium, exceto para as doses maiores que 2 mmol.L-1 das nanopartículas revestidas com quitosana. Os per-centuais de animais com alterações anatômicas foram similares entre os grupos tra-tados e de controle. Nos ensaios de locomoção e exploração, apenas as nanopartícu-las de quitosana e de sílica induziram alterações adversas significativas.Submitted by PPG Engenharia e Tecnologia de Materiais (engenharia.pg.materiais@pucrs.br) on 2018-05-17T18:27:28Z No. of bitstreams: 1 Tese - Elisa Magno Nunes de Oliveira.pdf: 7318970 bytes, checksum: a50f399a4afea119cd760c93cd71ff72 (MD5)Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-05-23T14:59:14Z (GMT) No. of bitstreams: 1 Tese - Elisa Magno Nunes de Oliveira.pdf: 7318970 bytes, checksum: a50f399a4afea119cd760c93cd71ff72 (MD5)Made available in DSpace on 2018-05-23T15:10:26Z (GMT). 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dc.title.por.fl_str_mv |
Agentes de contraste nanoestruturados a base de óxido de ferro : síntese, caracterização e avaliação toxicológica |
title |
Agentes de contraste nanoestruturados a base de óxido de ferro : síntese, caracterização e avaliação toxicológica |
spellingShingle |
Agentes de contraste nanoestruturados a base de óxido de ferro : síntese, caracterização e avaliação toxicológica Oliveira, Elisa Magno Nunes de Nanopartículas Magnéticas Agentes de Contraste Imagens Biomédicas Toxicidade Biomedical Imaging Toxicity Magnetic Nanoparticles Contrast Agent ENGENHARIAS |
title_short |
Agentes de contraste nanoestruturados a base de óxido de ferro : síntese, caracterização e avaliação toxicológica |
title_full |
Agentes de contraste nanoestruturados a base de óxido de ferro : síntese, caracterização e avaliação toxicológica |
title_fullStr |
Agentes de contraste nanoestruturados a base de óxido de ferro : síntese, caracterização e avaliação toxicológica |
title_full_unstemmed |
Agentes de contraste nanoestruturados a base de óxido de ferro : síntese, caracterização e avaliação toxicológica |
title_sort |
Agentes de contraste nanoestruturados a base de óxido de ferro : síntese, caracterização e avaliação toxicológica |
author |
Oliveira, Elisa Magno Nunes de |
author_facet |
Oliveira, Elisa Magno Nunes de |
author_role |
author |
dc.contributor.advisor1.fl_str_mv |
Papaléo, Ricardo Meurer |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/1933730859000512 |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/9837215819121108 |
dc.contributor.author.fl_str_mv |
Oliveira, Elisa Magno Nunes de |
contributor_str_mv |
Papaléo, Ricardo Meurer |
dc.subject.por.fl_str_mv |
Nanopartículas Magnéticas Agentes de Contraste Imagens Biomédicas Toxicidade Biomedical Imaging Toxicity |
topic |
Nanopartículas Magnéticas Agentes de Contraste Imagens Biomédicas Toxicidade Biomedical Imaging Toxicity Magnetic Nanoparticles Contrast Agent ENGENHARIAS |
dc.subject.eng.fl_str_mv |
Magnetic Nanoparticles Contrast Agent |
dc.subject.cnpq.fl_str_mv |
ENGENHARIAS |
description |
The present study focuses on the development of nanoparticles with an iron oxide magnetic core, with different biocompatible coatings, and on a comparative study of their toxicities. Uncoated and dextran-, chitosan-, polyethylene glycol- and silica-coated nanoparticles were synthesized. The addition of optical markers of the benzo-thiazoles class was also accomplished. The physico-chemical properties of the nano-particles were characterized, including their magnetic, optical and contrast properties in nuclear magnetic resonance imaging (relaxivities). In the particular case of nanopar-ticles functionalized with 6-OH-BTA-1 molecules, the affinity to the beta-amyloid pep-tide was also investigated. A second step was to evaluate the toxicological effects of these nanoparticles in vitro (using in VERO cells), and in vivo with zebrafish as an animal model. The size of the nanoparticles with the coatings ranged from 13 to 30 nm. Their crystalline structure was consistent with the ferrite spinel. The nanoparticles, independent of the coating, did not present residual magnetization and hysteresis, in-dicating superparamagnetic behaviour. For most nanoparticles, the r2 transverse re-laxivity values ranged from 76-64 mM-1.s-1, exceptfor uncoated and chitosan-coated nanoparticles, which present higher values, possibly due to the aggregation. The val-ues of r1 were similar for all nanoparticles (12.6 to 18 mM-1.s-1), with the exception of silica-coated nanoparticles (r1=2.1 mM-1.s-1). The r2/r1 ratios were between 4 and 17, typical of commercially available negative contrast-agents. The nanoparticles function-alized with benzothiazoles showed fluorescence with a Stokes shift of the emission peak of ~ 197 nm. The interaction of the beta-amyloid peptide with the 6-OH-BTA-1 molecule analyzed by fluorescence suppression is characterized by a static mecha-nism and Stern-Volmer constants of 1.53x104 mM-1 for the monomeric form, 1.40x104 mM -1 for oligomers) and 1.33x104 mM -1 for amyloid plaques.The in vitro toxicity assays indicated acceptable values of cell viability for iron concentration up to 2 mmol.L-1. The nanoparticles with the carboxysilane and polyethylene glycol showed higher biocom-patibility and silica-coated nanoparticles had the highest cytotoxicity. The in vivo as-says did not show significant changes in survival and hatchability rates, except for doses greater than 2 mmol.L-1 in the case of the chitosan-coated nanoparticles. The percentages of animals with anatomical alterations were similar between the treated and control groups. In the locomotion and exploration tests, only chitosan- and silica-coated nanoparticles induced significant changes. |
publishDate |
2018 |
dc.date.accessioned.fl_str_mv |
2018-05-23T15:10:26Z |
dc.date.issued.fl_str_mv |
2018-03-20 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
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info:eu-repo/semantics/doctoralThesis |
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doctoralThesis |
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publishedVersion |
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http://tede2.pucrs.br/tede2/handle/tede/8073 |
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http://tede2.pucrs.br/tede2/handle/tede/8073 |
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por |
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por |
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500 500 600 |
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4518971056484826825 |
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2075167498588264571 |
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info:eu-repo/semantics/openAccess |
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Pontifícia Universidade Católica do Rio Grande do Sul |
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