Preparação e caracterização de fluidos magnéticos de maghemita funcionalizada com o aminoácido L-Lisina e dextrana para carreamento de plasmídeos

Abstract

In this work magnetic nanoparticles composed of maghemite coated with L-lysine or DL-Histidine (crystallite average diameter between 4.5 to 8.1 nm.) were synthesized via the Fe (II) and Fe (III) coprecipitation method. The synthesized solids were dispersed in water to obtain aqueous suspensions called magnetic fluids. The samples were characterized by X-ray diffraction, infrared spectroscopy, thermogravimetry, UV-Vis spectrophotometry, transmission electron microscopy, electrophoretic and dynamic light scattering. The suspended colloidal nanoparticles showed positive zeta potential at physiological pH, which enables the adsorption of negatively charged molecules of chromosomal and plasmid DNA on their surfaces. Their hydrodynamic radius were smaller than those reported in the literature (100nm) allowing phagocytosis of the nanostructure. A maghemite/L-Lysine sample was selected for DNA adsorption (chromosomal DNA of Humicola grisea fungus and shRNA and GFP encoding plasmids) and subsequent coating with dextran, for protection of its genetic information. Plasmids and dextran adsorption was evidenced by the increasing of the hydrodynamic radius of the samples, and the presence of DNA and dextran related bands in the infrared.