Gomez-Pineda, E.A. (Edgardo Alfonso)

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    Superparamagnetic maghemite loaded poly ([epsilon]- caprolactone) nanocapsules: characterization and synthesis optimization
    (Latin-American Materials Network, 2014) Agüeros, M. (Maite); Gomez-Pineda, E.A. (Edgardo Alfonso); Oliveira, A.J.A. (Adilson J.A.) de; Farooqi, A.A. (Ammad A.); Winkler-Hechenleitner, A.A. (Ana Adelina); Peñalva, R. (Rebeca); Silva, M.F. (Marcela F.); Ciciliatti, M.A. (Mariani A.); Irache, J.M. (Juan Manuel)
    Iron oxide nanoparticles (ION) have been studied for essential applications, like detection of biological constituents (virus, bacterials, cell, nucleic acids, protein, enzyme, etc.), magnetic bioseparation and clinic therapy and diagnosis (such as MRI magnetic fluid and hyperthermia). In this work, γ-Fe2O3 has been synthetized by a adapted sol-gel method and entraped in poly ε-caprolactone (PCL) nanocapsules. The superparamagnetic nanocapsules have been formulated by double emulsion evaporation method. Some variables affecting the polydispersity index, zeta potential surface and size of nanocapsules were studied aiming optimize the formulation process of maghemite-loaded PCL nanocapsules. The following parameters were selected: sonication time, PCL concentration in organic phase, PVA concentration in external aqueous phase and maghemite/PCL weight ratio. Under these experimental conditions, the resulting nanocapsules displayed a mean size of about 346 nm and a maghemite content of about 7.5 μg/mg of nanocapsules and superparamagnetic behaviour at room temperature.
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    Study of thermal degradation of PLGA, PLGA nanospheres and PLGA/Maghemite superparamagnetic nanospheres
    (ABM; ABC; ABPol, 2015) Aparicio-de-Oliveira, A.J. (Adilson Jesús); Fernandes-Silva, M. (Marcela); Gomez-Pineda, E.A. (Edgardo Alfonso); Winkler-Hechenleitner, A.A. (Ana Adelina); Irache, J.M. (Juan Manuel)
    Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively studied because of its biomedical applications. Therefore, it is very important to know thermal properties of these materials in addition to other physical properties. Thermal degradation activation energy (Eα) of PLGA nanospheres with maghemite entrapment (PLGA-Mag), PLGA nanospheres (hollow spheres) (PLGA-H) obtained by an emulsion method and unprocessed PLGA (PLGA-R) were calculated by isoconversional Vyazovkin method based on data of TG analysis in order to evaluate modifications in thermal behavior caused by nanospheres obtainment process or by maghemite entrapment. Both hydrodynamic diameter in the range of 200-250 nm and polydispersity index lower than 0.3 are considered satisfactory. Thermal degradation of PLGA-R begins at higher temperatures than those of PLGA-H and PLGA-Mag, but processed samples presented increase in thermal stability, which was greater before processing by emulsion and in the presence of the magnetic materials. PLGA-Mag presents superparamagnetic behavior at room temperature.
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    Optimization of maghemite-loaded PLGA nanospheres for biomedical applications
    (Elsevier, 2013) Fernandes-Silva, M. (Marcela); Agüeros, M. (Maite); Gomez-Pineda, E.A. (Edgardo Alfonso); Winkler-Hechenleitner, A.A. (Ana Adelina); Peñalva, R. (Rebeca); Irache, J.M. (Juan Manuel); Oliveira, D.M.F. (Daniela M.F.) de
    Magnetic nanoparticles have been proposed as interesting tools for biomedical purposes. One of their promising utilization is the MRI in which magnetic substances like maghemite are used in a nanometric size and encapsulated within locally biodegradable nanoparticles. In this work, maghemite has been obtained by a modified sol-gel method and encapsulated in polymer-based nanospheres. The nanospheres have been prepared by single emulsion evaporation method. The different parameters influencing the size, polydispersity index and zeta potential surface of nanospheres were investigated. The size of nanospheres was found to increase as the concentration of PLGA increases, but lower sizes were obtained for 3 min of sonication time and surfactant concentration of 1%. Zeta potential response of magnetic nanospheres towards pH variation was similar to that of maghemite-free nanospheres confirming the encapsulation of maghemite within PLGA nanospheres. The maghemite entrapment efficiency and maghemite content for nanospheres are 12% and 0.59% w/w respectively.