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Browsing by Author "Valadares, Marize Campos"

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  • Avaliação de citotoxicidade de nanotransportadores sem substância ativa em função da sua densidade populacional
    Publication . Costa, Daniela; Sousa, Marcelo; Amaral, Joana S.; Lima, Eliana; Valadares, Marize Campos
    A par da evolução da nanotecnologia, assiste-se a uma crescente preocupação sobre eventuais riscos/toxicidade que os nanotransportadores possam representar [1]. A maioria dos trabalhos publicados relativos à avaliação da citotoxicidade in vitro de nanotransportadores (NT) incide na comparação quando a substância ativa (SA) é administrada em solução ou nanoencapsulada, sendo escassos os estudos que visam avaliar a possível toxicidade do NT por si só (sem SA). O objetivo deste trabalho consistiu na avaliação da citotoxicidade de NT sem SA em função da sua densidade populacional, tendo sido testados quatro NT distintos: nanocápsulas (NC), nanoesferas (NE), transportadores lipídicos nanoestruturados (NLC) e lipossomas, com oito densidades populacionais (diluições décimais de 2,10×1012 part/mL a 2,10×105 part/mL). A avaliação da citotoxicidade realizou-se numa cultura primária (linfócitos) pelo teste do MTT e numa linha celular (fibroblastos 3T3) pelo teste do vermelho neutro (NR).
    2013Conference object Open access Show more
  • Biodegradable nanoparticles designed for drug delivery: The number of nanoparticles impacts on cytotoxicity
    Publication . Mendes, Lívia Palmerston; Delgado, Jorge; Costa, Ângela Daniela Alves; Vieira, Marcelo Sousa; Benfica, Poliana Lopes; Lima, Eliana; Valadares, Marize Campos
    Nanostructured drug delivery systems are based on biocompatible and biodegradable components. Composition, size and membrane surface properties are characteristics that may influence cell viability in cytotoxicity assays. In this work, four nanostructured systems commonly used for drug delivery were prepared and cytotoxicity was evaluated on human lymphocytes and Balb/c 3T3 fibroblasts. The hemolytic potential was also investigated. Polymeric nanocapsules (NC) and nanospheres (NS), nanostructured lipid carriers (NLC) and liposomes were prepared and characterized for size, distribution, zeta potential and number per volume of the colloidal dispersion. Cell viability was evaluated, 24 and 48h, by MTT and neutral red assays (NR). Cells were incubated with each particle in eight different dilutions varying from 2.1×10 4 < /sup > to 2.1×10 < sup > 11 < /sup > particles/mL. Diameter of nanoparticles was between 130 and 200nm, all samples exhibited narrow size distribution (polydispersity index below 0.1) and zeta potential varied from -6.8 to -19.5mV. NC, NS and NLC reduced cell viability in a dilution dependent manner. For these nanoparticles, the higher number of particles induced cell death for both cell types. Liposomes did not cause loss of cell viability even at the highest number of particles. Results suggest that, depending on the kind of nanoparticle, the number of particles in the dispersion can negatively influence cell viability in pre-clinical drug development.
    2015Journal article Open access Show more