DEFAR - Departamento de Farmácia

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/530

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2005 - 20084

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Autor: search.filters.author.Vilela, José Mário CarneiroAssunto: search.filters.subject.Nanocapsules

Resultados da Pesquisa

Agora exibindo 1 - 4 de 4
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    PLA-PEG nanocapsules radiolabeled with 99mTechnetium-HMPAO : release properties and physicochemical characterization by atomic force microscopy and photon correlation spectroscopy.
    (2008) Pereira, Maira Alves; Mosqueira, Vanessa Carla Furtado; Vilela, José Mário Carneiro; Andrade, Margareth Spangler; Ramaldes, Gilson Andrade; Cardoso, Valbert Nascimento
    The present work describes the preparation, characterization and labelling of conventional and surface-modified nanocapsules (NC) with 99mTc-HMPAO. The size, size distribution and homogeneity were determined by photon correlation spectroscopy (PCS) and zeta potential by laser doppler anemometry. The morphology and the structural organization were evaluated by atomic force microscopy (AFM). The stability and release profile of the NC were determined in vitro in plasma. The results showed that the use of methylene blue induces significant increase in the encapsulation efficiency of 99mTc-HMPAO, from 24.4 to 49.8% in PLANC and 22.37 to 52.93% in the case of PLA-PEGNC(P < 0.05) by improving the complex stabilization. The average diameter of NC calculated by PCS varied from 216 to 323 nm, while the average diameter determined by AFM varied from 238 to 426 nm. The AFM analysis of diameter/height ratios suggested a greater homogeneity of the surface-modified PLAPEG nanocapsules compared to PLA NC concerning their flattening properties. The in vitro release of the 99mTc-HMPAO in plasma medium was faster for the conventional PLA NC than for the surface-modified NC. For the latter, 60% of the radioactivity remained associated with NC, even after 12h of incubation. The results suggest that the surface-modified 99mTc-HMPAO-PLA PEG NCwas more stable against label leakage in the presence of proteins and could present better performance as radiotracer in vivo.
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    Polymeric nanostructures for drug delivery : characterization by atomic force microscopy.
    (2005) Mosqueira, Vanessa Carla Furtado; Leite, Elaine Amaral; Barros, Cristina Maria de; Vilela, José Mário Carneiro; Andrade, Margareth Spangler
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    Release profiles and morphological characterization by atomic force microscopy and photon correlation spectroscopy of 99mTechnetium-fluconazole nanocapsules.
    (2008) Assis, Danielle Nogueira de; Mosqueira, Vanessa Carla Furtado; Vilela, José Mário Carneiro; Andrade, Margareth Spangler; Cardoso, Valbert Nascimento
    Several classes of antifungal have been employed in candidiasis treatment, but patients with advanced immunodeficiency can present unsatisfactory results after therapy. In these cases, high doses of drugs or the use of multiple agents are sometimes used, and hence increasing the risk of serious side effects. Considering theses difficulties, the encapsulation of antifungal agents in nanoparticulate carriers has been used with the objective of modifying the pharmacokinetic of drugs resulting in more efficient treatments with less side effects. The purpose of this work was the preparation, characterization and the investigation of the release profiles of radiolabeled fluconazole nanocapsules. The size, homogeneity and zeta potential of NC preparations were determined with a Zetasizer 3000HS. The morphology and the structural organization were evaluated by atomic force microscopy (AFM). The release study in vitro of NC was evaluated in physiologic solution with or without 70% mouse plasma. The labeling yield of fluconazole with 99mTc was 94% and the radiolabeled drug was stable within 24 h period. The encapsulation percentage of 99mTc-fluconazole in PLA-POLOX NC and PLA-PEG NC was approximately of 30%. The average diameter calculated by photon correlation spectroscopy (PCS) varied from 236 to 356 nm, while the average diameter determined by AFM varied from 238 to 411 nm. The diameter/height relation decreased significantly when 25% glutaraldehyde was used for NC fixation on mica. The zeta potential varied from −55 to −69 nm and surface-modified NC showed lower absolute values than conventional NC. The in vitro release of 99mTc-fluconazole in plasma medium of the conventional and surface-modified NC was greater than in saline. The drug release in plasma medium from conventional NC was faster than for surface-modified NC. The results obtained in this work suggest that the nanocapsules containing fluconazole could be used to identify infectious foci, due to the properties, such as size, zeta potential and controlled release of 99mTc-fluconazole. The surface-modified nanocapsules could constitute a long-circulating intravenous formulation of fluconazole for treating sepsis caused by disseminated form of candidiasis. However, in vivo studies should be considered and are under investigation.
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    Poly-caprolactone nanocapsules morphological features by atomic force microscopy.
    (2005) Leite, Elaine Amaral; Vilela, José Mário Carneiro; Mosqueira, Vanessa Carla Furtado; Andrade, Margareth Spangler