Nanopartículas magnéticas funcionalizadas com bicamada de ácido láurico: caracterização, associação de moléculas bioativas e estudo de interação com BSA
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2012-10-11
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Universidade Federal de Goiás
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Magnetic nanoparticles with two different chemical compositions, magnetite and zinc doped manganese ferrite were synthesized, functionalized with lauric acid bilayers and dispersed into water yielding stable aqueous colloidal suspensions at physiological pH. Bioactive molecules of different sizes, Amphotericin B and curcumin, were associated to the lauric acid bilayers of the suspended nanoparticles. X-ray diffraction analyses reveled a diffraction pattern characteristic of the cubic spinel crystalline phase for both samples. The nanoparticles average size estimated by Debye-Scherrer’s formula was 9 nm for zinc doped manganese ferrite and 8 nm for magnetite. The hysteresis curves showed that the nanoparticles are super paramagnetic at room temperature with saturation magnetization of 44.2 emug-1 for zinc doped manganese ferrite and 51.5 emug-1 for magnetite. The IR analysis showed the presence of lauric acid associated to the nanoparticles, and the TG curves showed a higher amount of lauric acid bonded to zinc doped manganese ferrite. The hydrodynamic diameters of the nanoparticles indicate that they are dispersed into the suspension as aggregates, and that the association of bioactive molecules did not affect the hydrodynamic sizes of the aggregates. The IR spectra confirmed the presence of bioactive molecules in the formulations and the UV-VIS spectra showed that these molecules are solubilized into the lauric acid bilayers in their monomeric forms. The functionalized nanoparticles containing the bioactive molecules present less negative zeta potential than the lauric acid functionalized nanoparticles, indicating that the bioactive molecules interact with the medium of the suspensions. The evaluation of aggregation of the nanoparticles in cell culture medium showed that the nanoparticles aggregation is significantly reduced by the addition of proteins (FBS and BSA) in cell culture medium. The study of interaction of the nanoparticles with bovine serum albumin before and after the association with the bioactive molecules showed that these systems present great affinity for BSA, with binding constants (Kb) in the range of 105 -106M-1. These results suggest that the nanoparticles functionalized with lauric acid bilayers, pure or associated to amphotericin B and curcumin, can be bioconjugated to proteins producing formulations with higher colloidal stability in biological media.
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SANTOS, Michelly Christine dos. Nanopartículas magnéticas funcionalizadas com bicamada de ácido láurico: caracterização, associação de moléculas bioativas e estudo de interação com BSA. 2012.90 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Goiânia, 2012.