Navegando por Palavras-chave "Aplicações biomédicas"

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    Estudo da deposição de hidroxiapatita sobre aço inoxidável via manufatura aditiva com laser
    (Universidade Federal de São Paulo, 2021-02-23) Soares, Thales Maziero [UNIFESP]; Oliveira, Aline Capella de [UNIFESP]; Trichês, Eliandra de Sousa [UNIFESP]; http://lattes.cnpq.br/1619405333024881; http://lattes.cnpq.br/1801648349786155; ttp://lattes.cnpq.br/3986762374558281
    Técnicas de manufatura aditiva, envolvendo processamento de metais e ligas metálicas, têm sido consideradas para produção de peças ou protótipos, a partir de materiais biocompatíveis de aplicação biomédica. Aços inoxidáveis austeníticos, como o 316L, são amplamente considerados na fabricação de implantes temporários, devido às suas boas propriedades mecânicas e sua resistência a corrosão, embora não sejam capazes de ligar-se ao tecido ósseo. Por outro lado, cerâmicas de fosfato de cálcio, como a hidroxiapatita (HA) são bioativas, mas apresentam elevada fragilidade sob solicitação mecânica. Dessa forma, a associação entre o aço inoxidável recoberto com HA apresenta-se como uma alternativa interessante em aplicações envolvendo formação óssea ao redor de peça implantada. Para isso, esse é um trabalho teórico, onde o objetivo é estudar viabilidades da deposição de HA sobre substrato de aço inoxidável 316L, via manufatura aditiva, utilizando laser, considerando os processos de fusão ou sinterização seletiva a laser. O trabalho mostra as possibilidades existentes para esse tipo de aplicação e analisa as dificuldades para aplicação do procedimento. Chegando à conclusão que é possível obter recobrimentos de Hidroxiapatita em aço inoxidável 316L com propriedades adequadas para uso biomédico, obtendo-se camadas uniformes e com controle de espessura, variando-se parâmetros do laser. Propõe-se trabalhos futuros com intuito de difundir a técnica e obter padrões de processamento para diversos tipos de prótese.
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    Síntese, caracterização e aplicações biomédicas de nanopartículas magnéticas
    (Universidade Federal de São Paulo, 2014-12-19) Britos, Tatiane Nassar [UNIFESP]; Ferreira, Paula Silvia Haddad [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    In the development of this work were performed syntheses and morphological characterization - structural and magnetic - of iron oxide nanoparticles and the Fe3O4 metal type (Fe0) which were obtained from the thermodecomposition and coprecipitation methods, respectively, and biological assays. The surfaces of these nanoparticles were functionalized with thiolated binders and hydrophilic (-SH), with the aim of making these biocompatible systems to act as carriers of nitric oxide (NO) and contrast agents in magnetic resonance imaging. Fe3O4 nanoparticles, such as magnetite, were synthesized by coprecipitation method, starting from FeCl3.6H2O FeCl2.4H2O salts and in acid medium. In a first step the surfaces of these nanoparticles were coated with a hydrophobic binder, such as oleic acid, in order to avoid clumping and to be subsequently exchanged for biocompatible thiolated binders and as mercaptosuccínico acid (MSA) and cysteine (Cys) Fe3O4 in mole ratios: MSA / Cys 1:40 to 1:20. Nanoparticles of Fe3O4-type MSA and Fe3O4-Cys were obtained with the direct coating their surfaces also. This second preparation step was conducted aiming to the optimization of the method of synthesis. Fe0 nanoparticles were synthesized by the method of the organometallic precursor thermodecomposition as iron III acetylacetonate [Fe(acac)3]. The thiolated nanoparticles were nitrosadic by sodium nitrite salt in a slightly acid, leading to the formation of magnetic systems nitric oxide donors (-SNO). These nanoparticles were characterized by a number of physicochemical techniques for verification of the structural, morphological and magnetic aspects and were tested as carrier of nitric oxide in culture of tumor cells and as contrast agents for stem cells also. The results showed that thiolated nanoparticles are crystalline, spherical and with narrow size distribution and showed superparamagnetic behavior. In addition, nitric oxide acts as a carrier for the treatment of cancer cells and as contrast agents for stem cells in magnetic resonance imaging.
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    Síntese, caracterização e ensaios biológicos de nanopartículas metálicas e bimetálicas
    (Universidade Federal de São Paulo, 2016-05-05) Santos, Marconi da Cruz [UNIFESP]; Ferreira, Paula Silvia Haddad [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Magnetic iron oxide nanoparticles (NPs) have been used in biomedical applications such as hyperthermia, drug carriers and as a contrast agent in magnetic resonance imaging. In this research, we synthesized and characterized iron oxide NPs (Fe3O4) and bimmetalic NPs Fe@Au. The syntheses of Fe3O4 were performed by coprecipitation of the salts FeCl3.6H2O and FeCl2.4H2O in aqueous media, by thermal decomposition of iron (III) acetylacetonate, Fe(acac)3, in organic medium, as well as by the polyol method in biocompatible organic solvent. In addition, Fe@Au was obtained by microemulsion method in reverse micelle. The functionalization of the NPs' surface with biocompatible molecules containing thiol groups (SH), cysteine (Cys) and glutathione (GSH) and the further nitrosation of its SH groups allowed the formation of S-nitrosothiol groups (S-NO) in the NPs' surface, which enables using these systems as nitric oxide (NO) carriers. The functionalization efficiency measurements of the thiolated NPs' surface were performed using Ellman?s reagent and a slightly acidified sodium nitrite solution (NaNO2) to nitrosate the SH groups in NPs' surface. By means of amperometric measurements we could detect and measure the NO releasing from nitrosated NPs. The structural, morphological and magnetic characterization showed spherical morphologies with low polydispersity in solid state, cubical structures compatible with magnetite. In order to improve biocompatibility and dispersion of these NPs in water, NPs' surface was coated with polyethylene glycol (PEG) beyond thiolated coatings (Cys and GSH). We evaluated the cytotoxicity of PL-Fe3O4-PEG and PL-Fe3O4-PEG-GSH in culture of tumor cells.