DEFAR - Artigos publicados em periódicos
URI permanente para esta coleçãohttp://www.hml.repositorio.ufop.br/handle/123456789/531
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Item Labeling PLA-PEG nanocarriers with IR780 : physical entrapment versus covalent attachment to polylactide.(2020) Machado, Marina Guimarães Carvalho; Lana, Gwenaelle Elza Nathalie Pound; Oliveira, Maria Alice de; Lanna, Elisa Gomes; Fialho, Márcia Célia Pacheco; Brito, Ana Carolina Ferreira de; Barboza, Ana Paula Moreira; Soares, Rodrigo Dian de Oliveira Aguiar; Mosqueira, Vanessa Carla FurtadoNear-infrared fluorescent dyes, such as IR780, are promising theranostics, acting as photosensitizers for photodynamic therapy and in vivo tracers in image-guided diagnosis. This work compared the uptake by macrophage-like cells of IR780 either physically associated or covalently attached to poly(D,L-lactide) (PLA) formulated as polymeric nanocapsules (NC) from a blend of PLA homopolymer and PLA-PEG block copolymer. The physicochemical characterization of both NC was conducted using asymmetric flow field-flow fractionation (AF4) analysis with static and dynamic light scattering and atomic force micros copy. The interaction of IR780 with serum proteins was evidenced by AF4 with fluorescence detection and flow cytometry in cell uptake studies. The average diameters of NC were around 120 nm and zeta potentials close to -40 mV for all NC. NC uptake by cells in different media and experimental conditions shows significantly lower fluorescence intensities for IR780 covalently linked to PLA and correspondingly low quantitative uptake. Different mechanisms of internalization were evidenced depending on the IR780 type of association to NC. Serum proteins mediate IR780 interaction with cells in a dose-dependent manner. Our results show that non-covalently linked IR780 was released from NC and accumulated in macrophage cells. Oppositely, IR780 conjugated to PLA provides stable association with NC, and its fluorescence is representative of cell uptake of the nanocarrier itself. This work strongly reinforces the importance of covalent attachment of a fluorescence dye such as IR780 to the nanocarrier to study their interaction with cells in vitro and to obtain reliable tracking in image-guided therapy.Item Biodistribution of free and encapsulated 99mTc-fluconazole in an infection model induced by Candida albicans.(2018) Assis, Danielle Nogueira de; Araújo, Raquel Silva; Fuscaldi, Leonardo Lima; Diniz, Simone Odília Antunes Fernandes; Mosqueira, Vanessa Carla Furtado; Cardoso, Valbert NascimentoCandida spp is an etiologic agent of fungal infections in hospitals and resistance to treatment with antifungals has been extensively reported. Thus, it is very important to develop formulations that increase effectiveness with low toxicity. In this sense, nanocarriers have been investigated, once they modify drug biodistribution profile. Thus, this study aimed to evaluate the biodistribution of free and encapsulated 99mTc-fluconazole into nanocapsules (NCs) in an experimental immunosuppressed murine model of Candida albicans infection.Item Interactions between a macrophage cell line (J774A1) and surface-modified poly(D, L-lactide) nanocapsules bearing poly(ethylene glycol).(1999) Mosqueira, Vanessa Carla Furtado; Legrand, Philippe; Gref, Ruxandra; Heurtault, Béatrice; Appel, M.; Barratt, GillianThe interactions of naked and surface-modified poly(D,L-lactic acid) (PLA) nanocapsules (NC), where polyethyleneglycol (PEG) was adsorbed or covalently attached, have been studied with a macrophage-like cell line. The fluorescent oil marker, DiD, was successfully encapsulated in NCs in order to follow their interactions with cells. The cell-associated fluorescence obtained with PEG-PLA NC was about 3- to 13-fold lower than that obtained with naked-PLA NC. The effects of PEG chain length, its content as a percentage of total polymer and NC concentration in the culture medium were evaluated. PEG-PLA NC showed dramatically reduced fluorescence association with cells during an 18 h incubation compared with naked-PLA NC, showing that covalent attachment of PEG is important for the persistence of low uptake. The best results in reducing cell-associated fluorescence were obtained with a surface-modified PEG-PLA NC bearing a chain with 20000 MW. Increasing the percentage of PEG produced a reduction in marker association for a given PEG chain length. Moreover, when the PEG-containing poloxamer was simply adsorbed, marker association was dependent on the extent of dilution and the type of serum in the culture medium. Serum proteins, especially immunoglobulins, increased cell-associated fluorescence for PEG-adsorbed NC, but had very little effect on PEG-PLA NC. Marker association was only partially inhibited in the presence of cytochalasin B. The mechanisms of cell-NC interaction depended on the characteristics of the NC surface in each formulation. When the NC was physically separated from cells no diffusion of fluorescent marker in aqueous medium occurred. Nevertheless, collision-mediated transfer of DiD from NC to J774 cells was a non-negligible route of marker transfer, mainly for naked NC. However, this collision-mediated transfer was reduced for the PEG-PLA NC probably due to the restricted contact between NC and cells afforded by PEG steric hindrance at the surface.Item Evaluation of short cycles of ultrasound application in nanoemulsions to obtain nanocapsules.(2015) Carneiro, Simone Pinto; Cruz, Ricardo Machado; Santos, Orlando David Henrique dosUltrasound is widely used in several chemical reactions and other process, including production of nanocapsules by in situ polymerization. In this work, the main objective was to evaluate the impacts and viability of successive ultrasound application in nanoemulsions to obtain nanocapsules. Initiator potassium persulfate (KPS) concentration, number of ultrasound cycles and reaction time influences on polymerization efficiency and droplet size were evaluated. This work revealed the successful in situ production of nanocapsules using successive shorts cycles of ultrasound. Number of cycles was the only parameter that not exerted significant influence in polymerization yield. Particle size decay was observed in all nanoemulsions after the first ultrasound application, the same was not observed in further cycles. Gravimetric assessment showed remarkable increase of monomer conversion, indicating that once started polymerization continued at least until 28 days after ultrasound application. Concluding, ultrasound short cycles can be used with no harm to formulation, if carefully performed and, furthermore is a potential cost-effective route for polymerization reactionsItem Nanotechnology applied to the treatment of malaria.(2010) Magalhães, Nereide Stela Santos; Mosqueira, Vanessa Carla FurtadoDespite the fact that we live in an era of advanced technology and innovation, infectious diseases, like malaria, continue to be one of the greatest health challenges worldwide. The main drawbacks of conventional malaria chemotherapy are the development of multiple drug resistance and the non-specific targeting to intracellular parasites, resulting in high dose requirements and subsequent intolerable toxicity. Nanosized carriers have been receiving special attention with the aim of minimizing the side effects of drug therapy, such as poor bioavailability and the selectivity of drugs. Several nanosized delivery systems have already proved their effectiveness in animal models for the treatment and prophylaxis of malaria. A number of strategies to deliver antimalarials using nanocarriers and the mechanisms that facilitate their targeting to Plasmodium spp.-infected cells are discussed in this review. Taking into account the peculiarities of malaria parasites, the focus is placed particularly on lipid-based (e.g., liposomes, solid lipid nanoparticles and nano and microemulsions) and polymer-based nanocarriers (nanocapsules and nanospheres). This review emphasizes the main requirements for developing new nanotechnology-based carriers as a promising choice in malaria treatment, especially in the case of severe cerebral malaria.Item 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 NascimentoThe 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.Item HPLC-FLD methods to quantify chloroaluminum phthalocyanine in nanoparticles, plasma and tissue : application in pharmacokinetic and biodistribution studies.(2011) Oliveira, Liliam Teixeira; Garcia, Giani Martins; Kano, Eunice Kazue; Tedesco, Antônio Cláudio; Mosqueira, Vanessa Carla FurtadoAnalytical and bioanalytical methods of high-performance liquid chromatography with fluorescence detection (HPLC-FLD) were developed and validated for the determination of chloroaluminum phthalocyanine in different formulations of polymeric nanocapsules, plasma and livers of mice. Plasma and homogenized liver samples were extracted with ethyl acetate, and zinc phthalocyanine was used as internal standard. The results indicated that the methods were linear and selective for all matrices studied. Analysis of accuracy and precision showed adequate values, with variations lower than 10% in biological samples and lower than 2% in analytical samples. The recoveries were as high as 96% and 99% in the plasma and livers, respectively. The quantification limit of the analytical method was 1.12 ng/ml, and the limits of quantification of the bioanalytical method were 15 ng/ml and 75 ng/g for plasma and liver samples, respectively. The bioanalytical method developed was sensitive in the ranges of 15–100 ng/ml in plasma and 75–500 ng/g in liver samples and was applied to studies of biodistribution and pharmacokinetics of AlClPc.Item 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 SpanglerItem 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 NascimentoSeveral 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.Item Relationship between complement activation, cellular uptake and surface physicochemical aspects of novel PEG-modifed nanocapsules.(2001) Mosqueira, Vanessa Carla Furtado; Legrand, Philippe; Gulik, Annette; Bourdon, Olivier; Gref, Ruxandra; Labarre, Denis; Barratt, GillianThe aim of our work was to examine the relationship between modi"cations of the surface of nanocapsules (NC) by adsorption or covalent grafting of poly(ethylene oxide) (PEG), and changes in their phospholipid (PL) content on complement activation (C3 cleavage) and on uptake by macrophages. The physicochemical characterization of the NC included an investigation of their properties, such as surface charge, size, hydrophilicity, morphology and homogeneity. This is the "rst time that such properties have been correlated with biological interactions for NC, a novel carrier system with a structure more complex than nanospheres. C3 crossed immunoelectrophoresis revealed the reduced activation for NC with longer PEG chain and higher density, although all formulations induced C3 cleavage to a lesser or greater extent. NC bearing PEG covalently bound to the surface were weaker activators of complement than plain PLA [poly(D,L-lactide)] NC or nanospheres (NS). Furthermore, the #uorescent/confocal microscopy of J774A1 cells in contact with NC reveal a dramatically reduced interaction with PEG-bearing NC. However, the way in which PEG was attached (covalent or adsorbed) seemed to a!ect the mechanism of uptake. Taken together, these results suggest that the low level of protein binding to NC covered with a high density of 20 kDa PEG chains is likely to be due to the steric barriers surrounding these particles, which prevents protein adsorption and reduces their interaction with macrophages. 2001 Elsevier Science Ltd. All rights reserved.